MSK Flashcards
Stress Fracture
Fracture resulting from the mismatch of bone strength and chronic mechanical force. They come in two flavors (A) Fatigue, and (B) Insufficiency.
Pathologic Fracture
You will sometimes hear people use this term synonymously with “Insufficiency
Fracture”. However, for the purpose of
multiple choice this term will most likely
refer to a fracture through a lvtic bone lesion.
These lytic lesions can be mets or be benign primary bone lesions (like an ABC, or Bone Cyst).
Open Fracture (Compound Fracture):
A fracture associated with an open wound. Typically these will go to the OR for reduction and washout - given the obvious risk for infection.
Tuft Fractures (finger tip fracture) with disruption o f the nail plate are considered “open” fractures - and although the typically won’t go to the OR they do get antibiotics (whereas an intact nail bed often won’t).
Fatigue Fracture
(sometime simply called a “stress fracture”).
Abnormal stress on Normal Bone.
Classic Scenario - Insane (but kinda hot) Type A Female Cross Country Runner - literally runs until her legs & feet break in half.
Insufficiency Fracture
Normal stress on Abnormal bone.
Classic Scenario - Old lady with horrible osteoporosis breaks her back (compression fracture) by walking down a few steps. She blames Obama for the fracture.
Phases of Fracture Healing
Overview
Physiology PhDs will describe 3 phases o f bone healing (Inflammatory, Reparative, and Remodeling). From a Radiologist’s perspective the most important thing to understand about this process is that around 7-14 days granulation tissue will be forming between the bone fragments. This results in an increased lucency o f the fracture site related to bone resorption.
In other words, a healing fracture will be MORE LUCENT at 7-14 days.
This explains the disclaimer cowardly Radiologists throw out when they are afraid they missed a fracture “Consider Repeat in 7-10 days, ” The idea is that in 7-10 days, you should be able to see the fracture line , if one is p re s e n t, because o f the increase in bone lucency that occurs normally in the healing process.
Fracture healing
overview
In general, bones heal in about 6-8 weeks, but is location dependent. Healing is the fastest in the phalanges (around 3 weeks), and the slowest is either the tibia or femoral neck/shaft - depending on what you read(around 2-3 months).
Phalanges healing
fast: 3 weeks
Tibia healing
slow: 10 weeks
Everything else healing
6-8 weeks
Delayed Union
fracture not healed within the expected time period (but still might). Some sources will say “twice as long as expected”
Non-Union
fracture is not going to heal without intervention. Some sources will say “6-9 months.’The classic locations are the scaphoid, anterior tibia, and lateral femoral neck.
Mal-Union
This is union in poor anatomic position (healed crooked as a politician).
Risk Factors For Abnormal Healing ( Delayed and Hon-Union)
Vitamin D deficiency
Vitamin D plays a vital role in calcium uptake and metabolism. Vitamin D deficiency is actually the most common vitamin deficiency in America (supposedly).
Risk Factors For Abnormal Healing ( Delayed and Hon-Union)
Gastric bypass
Having your gut rewired results in altered calcium absorption (causes secondary hyperparathyroid and stripping of calcium from bones) and therefore higher rates of nonunion.
Risk Factors For Abnormal Healing ( Delayed and Hon-Union)
Drugs/MEds
Tobacco (Smoking or Chewing)
NSA1DS
Prednisone (steroids)
THIS v s THAT-C om p re s s iv e Side vs T e n s ile Side:
- Fractures of the Compressive side are constantly pushed back together - these do well.
- Fractures of the Tensile side arc constantly pulled apart - these are a pain in the ass to heal.
Tibial Stress Fx
This is the most common site o f a stress fracture in young athletes.
These arc most common on the compressive side (posterior medial) in either the proximal or distal third.
Less common are the tensile side (anterior) fractures, and these favor the mid shaft. They arc bad news and don’t heal -often called “dreaded
black lines.’”
Femoral Stress Fx
Fractures along the compressive (medial) side are more common, typically seen in a younger person along the inferior femoral neck.
Fractures along the tensile (lateral) side arc more common in old people.
SONK (S p o n tan eo u s O s te o n e c ro s is o f th e K ne e)
overview
This is totally named wrong, as it is another type of insufficiency fracture. You see this in old ladies with the classic history o f “sudden pain after rising from a seated position.” Young people can get it too (much less common), usually seen after a meniscal surgery.
SONK (S p o n tan eo u s O s te o n e c ro s is o f th e K ne e)
key factoids
- It’s an insufficiency fracture (NOT osteonecrosis) think SINK not SONK
- Favors the medial femoral condyle (area o f maximum weight bearing)
- Usually unilateral in an old lady without history o f trauma
- Associated with meniscal injury
N a v icu la r S t r e s s F ra c tu r e
You see these in runners who run on hard surfaces. The thing to know is that ju st like in the wrist (scaphoid), the navicular is high risk for AVN.
March fracture
This is a metatarsal stress fracture which is fairly common. Classically seen in military recruits that are marching all day long.
Calcaneal Stress Fracture
The calcaneus is actually the most fractured tarsal bone. The fractures are usually intra-articular (75%). The stress fracture will be seen with the fracture line perpendicular to the trabecular lines.
You’ll rue the day you crossed me Trebek—ular Lines.
High risk stress fractures
Femoral neck
transverse patellar fx
anterior tibial fx (midshaft)
5th metatarsal
talus
tarsal navicular
sesamoid great toe
Lowe risk stress fractures
Femoral neck (compressive side)
longitudinal patellar fx
posterior medial tibial fracture
2nd and 3rd metatarsals
calcaneus
Scaphoid Fracture
overview
Most common carpal bone fracture.
Typical age group is an adolescents and young adults (Grandma is more likely to get a distal radial fracture with a similar mechanism — fall).
Blood flow is “retrograde” (distal to proximal). This is because the scaphoid surface is almost entirely (80%) covered with cartilage.
As such, the proximal pole most susceptible to AVN and Non- Union.
The first sign of AVN = Sclerosis (the dead bone can’t turn over /recycle)
Most common (70 %) fracture site = waist
Displacement of > 1 mm will likely get a fixation screw to pull the fragments together.
“Retrograde” (distal to proximal) via the Dorsal Carpal Branch of Radial Artery
Scaphoid Fracture
Trans-Scaphoid
Perilunate Dislocation
60% association with a scaphoid fx
Scaphoid Fracture
Humpback deformity
This deformity results from angulation of the proximal and distal fragments - in the setting of a waist fracture.
Can progress to progressive collapse and non-union.
Associated with D1S1
Scaphoid Fracture
Scapholunate Ligament
Disruption
Seen with 10-30% of distal radius and/or carpal fractures
The SL ligament is composed of 3 parts (volar, dorsal, and middle), with the dorsal band being the most important for carpal stability (opposite o f luno triquetral which is volar).
Disruption of the ligament predisposes for DISI deformity
Gap >3 mm
Scaphoid Fracture
AVN
the proximal pole is at greatest risk.
The first sign of AVN = Sclerosis (the adjacent bones will demineralize, but the avascular bone will not). Later the bone will fragment.
MRI = T1 Dark
Trivia: “Prieser Disease” is an atraumatic AVN of the scaphoid
SLAC and SNAC Wrists
Overview
Both are potential complications of trauma, with similar mechanisms.
SLAC Wrist (Scaphoid-Lunate Advanced Collapse) occurs with injury (or degeneration via CPPD) to the S-L ligament.
SNAC Wrist (Scaphoid Non-Union Advanced Collapse) occurs with a scaphoid fracture.
Just remember that the scaphoid always wants to rotate in flexion - the scaphoid-lunate ligament is the only thing holding it back. If this ligament breaks it will tilt into flexion, messing up the dynamics of the wrist. The radial scaphoid space will narrow, and the capitate will migrate proximally.
SLAC and SNAC wrists
Treatment
depends on the occupation/needs of the wrist. Wrist fusion will maximize strength, but cause a loss of motion. Proximal row carpectomy will maximize ROM, but cause a loss of strength.
SLAC and SNAC wrists
trivia
- Radioscaphoid joint is first to develop degenerative changes
- Capitate will migrate proximally and there will eventually be a DISI deformity
Scapholunate Ligament Tear
The Terry Thomas look (gap between the scaphoid and lunate) on plain film.
There are actually 3 parts (volar, dorsal, and middle), with the dorsal band being the most important for carpal stability. If they tear the carpals will migrate away from each other.
Predisposed for DISI deformity
DISI Vs VISI
Overview
1 imagine two people (Lunate and Scaphoid) standing on opposite sides o f a very steep hill. At the apex o f the hill is
a man named “Scapholunate Ligament” - 1 agree, it’s a strange name. His parents were probably vegetarians.
This hill is very steep, so Scapholunate Ligament has grabbed each of the people (Lunate and Scaphoid) by the
hand - he was worried they might fall. In fact, the only thing keeping these two people from tumbling down the hill is the insane grip strength o f Scapholunate Ligament (rumor has it he can close a #3 Captain o f Crush - which would certify him as an official Captain o f Crush).
By using this analogy perhaps you can infer that if you have carpal ligament disruption, the carpal bones will rotate the way they naturally want to (down the hill). The reasons for their rotational desires are complex but basically have to do with the shape of the fossa they sit on.
Just remember the scaphoid wants to flex (rock volar) and the lunate wants to extend (rock dorsal). The only thing holding them back is their ligamentous attachment to each other.
DISI
Dorsal Intercalated Segmental Instability
Overview
1 like to call this dorsiflexion instability because it helps me remember what’s going on. After a “Radial sided injury” (scapholunate side), the lunate becomes free o f the stabilizing force o f the scaphoid and rocks dorsal ly. Remember SL ligament injury is common, so this is common.
DISI
Dorsal Intercalated Segmental Instability
main
Widening of the SL angle - with dorsiflexion of the lunate.
Angle greater than 60 degrees
VISI (Volar Intercalated Segmental Instability)
Overview
I like to call this volar-flexion (palmar-flexion) instability because it helps me remember what’s going on. After a “Ulnar sided injury” (lunotriquetral side), the lunate no longer has the stabilizing force of the lunotriquetral ligament and gets ripped volar with the scaphoid (remember the scaphoid stays up late every night dreaming o f tilting volar).
Remember LT ligament injury is not common, so this is not common. It’s so uncommon in fact that if you see it - it’s probably a normal variant due to wrist laxity.
VISI (Volar Intercalated Segmental Instability)
main
Narrowing of the SL angle - with volar-flexion of the lunate & scaphoid. Angle < 30 (this acute angle looks like a V to me - “V” for “V")
Scapho-Lunate
Dissociation
sl wider than 3 mm
clenched fist few can worsen it
chronic sl dissocation can result in a slac wrist
Peri-Lunate
Dislocation
the lunate stays put. its the carpal bones around the lunate that move
6-% are associated with scaphoid fxs
Mid-Carpal
Dislocation
both lunate and capitate lose radial alignment
associated with triquetro lunate interosseous ligament disruption
associated with triquestral fracture
Lunate dislocation
luante move easy, others stay
it happens with a dorsal radiolunate ligament injury
most severe
Lunate dislocations
lesser arc
Pure Ligament Injury (No
Fractures)
Lunate dislocations
greater arc
Associated with fractures.
Described by saying “trans” the name of the fracture then the dislocation. Example “Trans-scaphoid, peri-lunate dislocation”
Lunate dislocations
space of poirier
Ligament free (“poor”) area, that is a site of weakness
Which synovia l s p a c e s of the wrist n o rm a lly c om m u n ic a te ?
The answer is pisiform recess and radiocarpal joint. l can think o f two ways to ask this (1) related to fluid - the bottom line is that excessive fluid in the pisiform recess should not be considered abnormal if there is a radiocarpal effusion, and (2) that either space can be used for wrist arthrography.
Glenohumeral Joint and
Subacromial Bursa
Should NOT communicate. Implies the presence o f a
full thickness rotator cuff tear.
Ankle Joint and Common
(lateral) Peroneal Tendon Sheath
Should NOT communicate. Implies a tear o f the
calcaneofibular Ligament.
Achilles Tendon and
Posterior Subtalar Joint
Should NOT communicate. The Achilles tendon
does NOT have a true tendon sheath.
Pisifrom Recess and
Radiocarpal Joint
should normally communicate
Triangular Fibrocartilage Complex — TFCC
overview
I’ll begin by saying that this is arguably the most complex anatomy in the entire body (maybe second only to the posterior lateral comer). A detailed understanding is well beyond the scope o f the exam (probably…). Having said that, the TFC is specifically mentioned on the official study guide, so we need to at least talk about it. The TFCC functions as the primary stabilizer and shock absorber o f the distal radial ulnar joint (DRUJ). The TFCC is critical for a range o f activities (doing a pushups , punching General Zod, e tc …).
It looks crazy complicated - but you really only need to know at most 5 structures, Of the 5, the Hand Surgeon only really gives a shit about the Articular Disc and Radioulnar Ligaments.
Triangular Fibrocartilage Complex — TFCC
mr signal
“TFC Proper” (Articular Disc) will be dark on every sequence.
The ulnar attachment often looks intermediate in signal, this is normal related to loose connective tissue in the region.
The radial attachment will also have intermediate signal, but this is from the normal articular cartilage.
Triangular Fibrocartilage Complex — TFCC
injuries
“Class 1” Acute Injuries: Usually via fall onto extended wrist.
“Class 2” Chronic Degeneration: These are more common, and associated with positive ulnar variance and ulnar impaction.
Central perforations are common - and might even be “expected” on an old person.
Central Tear, with Ulnar Positive Variance and Abutment (cystic change in the lunate) -
Triangular Fibrocartilage Complex — TFCC
vasculature and healing
Similar to how the knee meniscus has “red” and “white” zones - the ulnar side o f the TFC is vascular and more likely to heal. Radial sided injuries are relatively avascular and less likely to heal.
Triangular Fibrocartilage Complex — TFCC
vasculature and healing
Similar to how the knee meniscus has “red” and “white” zones - the ulnar side o f the TFC is vascular and more likely to heal. Radial sided injuries are relatively avascular and less likely to heal.
U ln a r V a r ia n c e
overview
This is determined by comparing the lengths o f the ulna and distal radius.
These length differences can occur congenitally, or be acquired from impaction / fracture deformity.
U ln a r V a r ia n c e
positive
Ulnar Impaction
Syndrome
U ln a r V a r ia n c e
negative
AVN o f the Lunate
“Kienbock”
U ln a r Im p a c tio n Syndrome
(U ln a r A b u tm e n t):
Seen with positive ulnar variance.
Essentially the distal ulna smashes into the lunate, degenerating it (cystic change / geodes e tc …) and tears up the TFCC.
Keinbocks
AVN o f the lunate, seen in people in their20s-40s. The most likely testable trivia is the association with negative ulnar variance. It’s going to show signal drop out on T1.
Collies fracture
(Outward) "Collie Dogs ” Like it Outside Distal Metaphysis Fx Dorsal Angulation Old Lady Fracture Ulnar Styloid Fx is Commonly Associated
Smith Fracture
(Inward) Distal Metaphysis Fx Volar Angulation Younger Patient Ulnar Styloid Fx is Commonly Associated
Barton Fx
(Dorsal or Volar) Radial Rim Fx Volar is More Common Radial-Carpal Dislocation is the “hallmark” Typically Surgical (they have a high rate of re dislocation /mal-union)
Radial Tilt
- There is a normal volar tilt o f around 11 degrees
- With distal radial fractures this can get fucked up
- Most Orthopods wo n ’t accept anything past neutral
- A TRUE lateral is necessary to measure it
How do yo u know yo u r lateral is “tru e “ ?
The volar cortex o f the pisiform overlies the central 1/3 o f the interval between the scaphoid and capitate
Wrist tendon extensor compartments
There are 6 extensor compartments (5 fingers + 1 for good luck).
First compartment (APL and EPB) are the ones affected in de Quervain’s
Third compartment has the EPL which courses beside Lister’s Tubercle.
The sixth compartment (Extensor Carpi Ulnaris) - can get an early tenosynovitis in rheumatoid arthritis.
Carpal Tunnel
overview
They could show you the carpal tunnel, but only to ask you about anatomy.
What goes through the carpal tunnel (more easily asked as “what does NOT go through ”)?
Knowing what is in (and not in) the carpal tunnel is high yield for multiple choice testing. The tunnel lies deep to the palmaris longus, and is defined by 4 bony prominences (pisiform, scaphoid tubercle, hook o f hamate, trapezium tubercle), with the transverse carpal ligament wrapping the contents in a fibrous sheath.
Carpal Tunnel
contents
- 4 Flexor D. Profudus (FDP)
- 4 Flexor D. Superficials (FDS)
- 1 Flexor Pollicis Longus (FPL), and
- 1 Median Nerve
Carpal Tunnel
FCR
The Flexor Carpi Radialis (FCR) is NOT truly in the tunnel.
The extensor tendons are on the other side o f the hand. Note that
Flexor Pollicis Longus (FPL) goes through the tunnel, but
Flexor Pollicis Brevis does not (it’s an intrinsic handle muscle).
Palmaris longus (if you have one) does NOT go through the
tunnel.
Carpal Tunnel
what does not go through it
-Flexor Carpi Radialis
-Flexor Carpi Ulnaris
-Palmaris Longus
(if you have one)
-Flexor Pollicis BREVIS
Carpal Tunnel Syndrome
- Median Nerve Distribution (thumb-radial aspect o f 4th digit), often bilateral, and may have thenar muscle atrophy.
- On Ultrasound, enlargement o f the nerve is the main thing to look for
- It’s usually from repetitive trauma,
- Trivia = Association with Dialysis. Pregnancy, DM, and HYPOthyroidism
Carpal Tunnel syndrome
classic findings
Classic Findings:
• Increased Signal in the Median Nerve
• The Nerve May Also Be Swollen or Look Smashed / Flattened
• Bowing of the Flexor Retinaculum
Guyon’s C an a l Syndrome
- Entrapment o f the ulnar nerve as it passes through Guyon’s canal (formed by the pisiform and the hamate - and the crap that connects them).
- Classically caused by handle bars “handle bar p a lsy.”
- Fracture o f the hook o f the hamate can also eat on that ulnar nerve.
Sub-Sheath T e a r / D is lo c a tio n
This refers to a traumatic dislocation to the extensor carpi ulnaris (ECU - compartment 6) out o f its normal groove at the level o f the distal ulna. This dislocation / subluxation implies rupture o f the overlying sheath.
Sub-Sheath T e a r / D is lo c a tio n
trivia
the direction of the dislocation is medial
Tuberculous or
Nontuberculous
Mycobacterial
tenosynovitis
Hand and wrist are the most common tendons affected
Diffuse exuberant tenosynovitis that spares the muscles.
Usually occurs in patients who are immunocompromised.
Discrete filling defects in the fluid filled sheaths (“rice bodies”) is a classic TB finding.
RA
Tenosynovitis
Multiple Flexor Tendons or Isolated Extensor Carpi Ulnaris if early (ECU =
Compartment 6)
Tenosynovitis can present as an early RA findings (before bone findings).
Penetrating infection
tenosynovitis
Tenosynovitis of any flexor tendon is a surgical emergency as it can spread rapidly to the common flexors of the wrist.
Increased pressure in the sheath can cause necrosis of the tendons.
Patients with delayed treatment tend to do terrible
Myocobacterium Marinum is usually direct infection in a fisherman or sushi chef.
Overuse
Tenosynovitis
This is going to be classic
locations like 1 st extensor compartment for De Quervains — discussed more below.
De Quervain’s Tenosynovitis:
So called “Washer Woman’s Sprain” or “Mommy Thumb.” Occurs from repetitive activity / overuse. The classic history is “new mom - holding a baby.”
First Extensor Compartment (Extensor Pollicis Brevis and Abductor Pollicis Longus
Finkelstein Test = Pain on passive ulnar deviation.
The presence or absence of an intratendinous septum (between the EPB and APB) - tendons on the is a prognostic factor. If its absent, this will nearly always resolve with conservative treatment alone.
De Quervain’s Tenosynovitis
imaging
Ultrasound: Increased fluid within the first extensor tendon compartment MRI: increased T2 signal in the tendon sheath
Intersection syndrome
tenosynovitis
A repetitive use issue (classically seen in rowers),
Occurs where the first extensor tendons, “intersects” the second extensor compartment tendons. The result is extensor carpi radialis brevis and longus tenosynovitis.
Occurs 5 CM proximaly to listers tubercle
Tenosynovitis overview
This is an inflammation of the tendon, with increased fluid seen around the tendon. This will be shown on MRI (or US).
B en n e tt and Rolando
F ra c tu re s :
- They are both fractures at the base o f the first metacarpal
- The Rolando fracture is comminuted (Bennett is not)
- Trivia: The pull o f the Abductor Pollicis Longus
G am e k e e p e r’s T h um b (S k ie r):
overview
• Avulsion fracture at the base o f the proximal first phalanx
associated with ulnar collateral ligament disruption.
• The frequently tested association is that o f a “S te n e r
Le s ion .” A Stener Lesion is when the Adductor tendon
aponeurosis gets caught in the tom edges o f the UCL.
The displaced ligament won’t heal right, and will need
surgery.
• It makes a “yo-yo” appearance on MRI - supposedly…
• Next Step - Don’t do “ stress views” that can cause a
stener. MRI is the more appropriate test.
G am e k e e p e r’s T h um b (S k ie r):
do not
DO NOT perform radiographic stress views for Gamekeepers Thumbs
this will make it a stener
G am e k e e p e r’s T h um b (S k ie r):
stener lesion
Ulnar collateral ligament is retracted and
displaced superficial to the adductor aponeurosis.
T rig g e r Finger:
The idea is the overuse /
repetitive trauma causes scarring in the flexor tendon sheath. The fancy word is “stenosing tenosynovitis.” This is most commonly shown with ultrasound. If
they should you a hand ultrasound think about this. Another common area o f “stenosing tenosynovitis” is
at the ankle specifically the flexor hallucis longus tendon around the ankle in patients with the os trigonum syndrome.
Elbow & Forearm
General trivia
- Radial Head Fracture is most common in adults (supracondylar is most common in PEDs)
- Sail sign - elevation o f the fat pads from a jo in t effusion. Supposedly a sign o f occult fracture. The testable trivia is (1) the posterior fat pad is more specific (posterior is positive), and (2) the posterior fat pad can appear falsely elevated (false positive) if the lateral isn’t a true 90 degree flexed lateral. “Posterior Positive, Posterior Position Dependent ”
- Capitellum fractures are associated with posterior dislocation
Fo re a rm F ra c tu re s / Eponyms
Overivew
Forearm fractures are “ring” or “pretzel” type fractures, similar to the pelvis or mandible. Think about breaking a pretzel, it always snaps in two spots (not ju st one). So forearm fractures are often two fractures, or a fracture + dislocation.
Fo re a rm F ra c tu re s / Eponyms
monteggia fracture (MUGR)
Fracture of the proximal ulna, with anterior dislocation of the radial head.
Dislocation of the radial head follows the angulation of the Ulnar Fx.
Fo re a rm F ra c tu re s / Eponyms
Galeazzi fracture (MUGR)
Radial shaft fracture, with anterior
dislocation of the ulna at the DRUJ.
Essex lopresti
Fracture of the radial head + Anterior dislocation of the distal radial ulnar joint.
Unstable fracture - With rupture of the interosseous membrane
C u b ita l Tu nne l Syndrome
overview
There are several causes - the most common in the real world is probably repetitive valgus stress. The most common shown on multiple choice is probably an accessory anconeus.
WTF is an “Anconeus ” ? It a piece o f shit muscle that does nothing but get in the way o f an orthopedic scope. It’s normally on the lateral side the elbow. You can have an “Accessory Anconeus ” - also called an “Anconeus Epitrochlearis ’’ - on the medial side which will exert mass effect on the ulnar nerve.
C u b ita l Tu nne l Syndrome
anatomy trivia
The site where the ulnar nerve passes beneath the cubital tunnel retinaculum also known as the epicondylo-olecranon ligament or Osborne’s ligament.
L a te ra l E p ico n d y litis
(more common than medial) - seen in Tennis Players -
• Extensor Tendon Injury (classically extensor carpi radialis brevis)
• Radial Collateral Ligament Complex - Tears due to varus stress
M ed ia l E p ico n d y litis
(less common than lateral) - seen in golfers
• Common flexor tendon and ulnar nerve may enlarge from chronic injury
P a r tia l U ln a r C o lla te ra l L ig am e n t T e a r:
For the exam all you really need to know is that throwers (people who valgus overload) hurt their ulnar collateral ligament (which attaches on the medial coronoid - sublimetubercle). The ligament has three bundles, and the anterior bundle is by far the most important. If you get any images it is most likely going to be of the partial UCL tear, described as the “T sign,” with contrast material extending medial to the tubercle
L ittle L e a g u e r E lb ow
The children of insecure men who sucked at sports in high school are most
susceptible to this injury. The mechanism is repetitive micro-trauma from
endless hours of training (necessary to finally rectify the injustice which
beset their family when dad was benched senior year from the junior varsity
baseball squad).
We are talking about a repetitive chronic injury to the medial epicondyle. When I say injury I mean stress fracture, avulsion, or delayed closure of the medial epicondvlar apophysis. This is usually associated with UCL injury.
Children aren’t the only ones who can fuck up their elbows pursuing the kind of immortality that is only offered to those worthy enough to step foot on the field at Yankee stadium. There is a well described “valgus overload syndrome” seen in throwers, consisting of a triad of lateral compression, medial tension, and posterior sheer. This mechanism results in UCL injury (often anterior band), Arthritis at the Posterior Humerus / Ulna, and the development of an OCD at the capitellum.
Epitrochlear lymphadenopathy
ct scratch disease
Dialysis elbow
This is the result of olecranon bursitis from constant pressure on the area, related to positioning of the arm during treatment.
Biceps Tear
overview
Tears can be partial or complete. When complete the tear typically occurs in shoulder with the tendon avulsing off the labrum (or at the level of the bicipital groove).
Common mechanism is incorrect deadlift form (while doing cross fit like an ape on cocaine). If you plan on going nuts slinging that shit around consider switching to a double over grip. If you want to use over under grips - you need strict form (keep your arms locked out dummy). There are tons of highlight reals on youtube of people tearing biceps while deadlifting - notice every single one is using an over under grip, and not maintaining straight arm technique.
PArtial Biceps Tear
gamesmanship
Partial tears often arc associated with bicipitoradial bursitis
Biceps Tear
gamesmanship
Injury to the bicep is associated with median nerve symptoms
Tricep rupture
The tricep tendon has the honorable distinction of being the LEAST common tendon in the body to rupture. Even tendinopathy is fairly uncommon relative to other nearby structures. When it does tear you should be thinking about salter harris II fractures of the olecranon - that is the classic scenario. 1 think because this is so uncommon that mimics would be more likely on the exam. So, I’d be aware of two things: (1) the normal striated appearance of the insertion at the olecranon, and (2) the common entity
of olecranon bursitis - which you should think of first if you see a bunch of fluid signal in the posterior elbow.
Elbow dislocation
overview
This is the second most common joint dislocated in the adult. The associated fractures are usually the radial head and the coronoid process.
Instability in the elbow (so called P o s te rio r R o ta ry In s ta b ility ) is described in a pattern starting in the posterior lateral comer with tearing o f the lateral UCL.
elbow dislocation
steps
Tearing of the LUCL (lateral UCL).
Partial Dislocation
Coronoid Perched on Trochlea
(LUCL + LCL + Capsule)
Dislocation
Coronoid Posterior to Humerus with a UCL Tear
Anterior Shoulder dislocation
Anterior inferior (subcoracoid) are by far the most common (like 90%).
o Hill-Sachs is on the Humerus.
o Hill-Sachs is on the posterior lateral humerus, and best seen on internal rotation view.
O Bankart - anterior inferior labrum
O Greater tuberosity avulsion fracture occurs in 10-15% o f anterior dislocations in patient’s over 40.
Posterior shoulder dislocation
Posterior Dislocation: uncommon - probably from seizure or electrocution
O Rim Sign - no overlap glenoid and humeral head
O Trough Sign - reverse Hill Sachs, impaction on anterior humerus
O “Light Bulb Sign ” - Arm may be locked in internal rotation on all views
Inferior dislocation
(lu.xatio erecta humeri) - this is an uncommon form, where the arm is sticking straight over the head. The thing to know is 60% get neurologic injury (usually the axillary nerve).
Hill-Sachs
Posterolateral humeral head
impaction fracture (anterior
dislocation)
Bankart
Anterior Glenoid Rim
anterior dislocation
Trough Sign
Anterior humeral head impaction
fracture (posterior dislocation)
Reverse Bankart
Posterior Glenoid Rim
posterior dislocation
Dislocation memory tool
1 remember that hip dislocations are posterior - from the straight leg dashboard mechanism.
Then I ju st remember that shoulders are the opposite o f that (the other one, is the other one).
Shoulder = Usually Anterior
Proximal humerus fx
This is usually in an old lady falling on an out stretched arm. Orthopods use the Neer classifications (how many parts the humerus is in ?). Three or four part fractures tend to do worse.
T h e Post Op S h o u ld e r (P ro s th e s is )
4 main types
Humeral Head Resurfacing, Hemi Arthroplasty, Total Shoulder Arthroplasty, and the Reverse Total Shoulder Arthroplasty.
T h e Post Op S h o u ld e r (P ro s th e s is )
reverse total shoulder
A conventional total shoulder mimics normal anatomy. A reserve total shoulder is the bizarro version; with a plastic cup on the humeral head and metallic sphere on the glenoid.
T h e Post Op S h o u ld e r (P ro s th e s is )
who gets what
glenoid and cuff intact - resurfacing or hemi
glenoid intact and cuff deficient - hemi or reverse
glenoid deficient cuff intact - TSA
Glenoid deficient and cuff deficient - reverse
T h e Post Op S h o u ld e r (P ro s th e s is )
complications/trivia
—Total Shoulder Most Common Complication = Loosening o f the Glenoid Component
—Total Shoulder Complication - “Anterior Escape ” - This describes anterior migration o f the humeral head after subscapularis failure.
— Reverse Total Shoulder Does NOT require an intact rotator cuff - patient rely heavily on the deltoid.
— Reverse Shoulder Complication - Posterior Acromion Fracture - from excessive deltoid tugging.
Impingement / Rotator Cuff Tears
overview
This is a high yield / confusing subject that is worth talking about in a little more detail. In
general, rotator cuff pathology is the result o f overuse activity (sports) or impingement
mechanisms. There are two types o f impingement with two major sub-divisions within those
types. Like many things in Radiology, if you get the vocabulary down, the pathology is easy to
understand.
Impingement / Rotator Cuff Tears
extranal overview
This refers to impingement o f the rotator cuff overlying the bursal surfaces (superficial surfaces) that are adjacent to the coracoacromial arch. As a reminder, the arch is made up o f the coracoid process, acromion, and coracoacromial ligament.
Impingement / Rotator Cuff Tears
external primary causes
(Abnormal Coracoacromial Arch) :
• The hooked acromion (type III Bigliani) is more associated with external impingement than the curved or flat types.
• Subacromial osteophyte formation or thickening o f the coracoacromial ligament
• Subcoracoid impingement: Impingement o f the subscapularis between the coracoid process and lesser tuberosity. This can be secondary to congenital configuration, or a configuration developed post traumatically after fracture o f the coracoid or lesser tuberosity.
Impingement / Rotator Cuff Tears
external secondary causes
(Normal Coracoacromial Arch):
• “Multidirectional Glenohumeral Instability” - resulting in micro-subluxation o f the humeral head in the glenoid, resulting in repeated micro-trauma. The important thing to know is this is typically seen in patients with generalized jo in t laxity, often involving both shoulders.
Impingement / Rotator Cuff Tears
internal overview
This refers to impingement o f the rotator cuff on the undersurface (deep surface) along the glenoid labrum and humeral head.
Impingement / Rotator Cuff Tears
internal posterior superior
This is a type o f impingement that occurs when the posterior superior rotator cuff (junction o f the supra and infraspinatus tendons) comes into contact with the posterior superior glenoid. Best seen in the ABER position, where these tendons get pinched between the labrum and greater tuberosity. This is seen in athletes who make overhead movements (throwers, tennis, swimming).
Impingement / Rotator Cuff Tears
internal anterior superior
This is internal impingement that occurs when the ann is in horizontal adduction and internal rotation. In this position, the undersurface o f the biceps and subscapularis tendon may impinge against the anterior superior glenoid rim.
External impingement primary
quick
’ Abnormal Coracoacromial Arch — Hook Shaped (B3) — Osteophytes —Post Traumatic — Thickened Ligaments
Subacromial - F’s with a supra S
Subacoracoid - F’s with Sub S
External impingement secondary
quick
Multidirectional Instability
— Labrum Often Normal
—“Increased Glenohumeral Volume” - with injection
Internal impingement posterior superior
quick
’Throwers
— F’s with Infraspinatus (and posterior Supra)
—Posterior Superior Labrum Torn
—Cystic Change in Greater Tuberosity
Internal impingement anterior superior
quick
—Associated with Sub Scapular damage (Maybe the cause rather than the result)
—Anterior Superior Labrum Torn
High Yield Trivia Points on Impingement
subacromial impingement
most common form, resulting from attrition o f the coracoacromial arch.
Damages Supraspinatus Tendon.
High Yield Trivia Points on Impingement
subcoracoid impingement
Lesser tuberosity and coracoid do the pinching.
Damages Subscapularis (remember the coracoid is anterior - an d so is the subscapularis).
High Yield Trivia Points on Impingement
posterior superior “internal” impingment
-A th le te s who make overhead movements. Greater tuberosity and posterior inferior labrum do the pinching.
Damages Infraspinatus (and posterior fibers o f the supraspinatus).
Rotator Cuff Tears
overview
People talk about these tears as either “Bursal Sided” (meaning the top part), or “Articular Sided” (meaning the undersurface).
A tear o f the articular surface is more common (3x more) than the bursal surface. The underlying mechanism is usually degenerative, although trauma can certainly play a role.
Rotator Cuff Tears
most common of the 4 muscles
Supraspinatus - with most tears occurring at the “ c r itic a lzo n e” - 1-2 cm from the tendon footprint. This relatively avascular “critical zone” is also the most common location for Calcium Hydroxyapatite (HADD) - or “calcific tendinitis.” The Teres Minor is the least common to tear.
Rotator Cuff Tears
partial tear
A partial tear that is > 50% often results in a surgical intervention.
Rotator Cuff Tears
massive rotator cuff tear
refers to at least 2 out o f the 4 rotator cuff muscles
Rotator Cuff Tears
general piece of trivia
A final general piece o f trivia is that a tear o f the fibrous rotator cuff interval (junction between anterior fibers o f the Supraspinatus and superior fibers o f the subscapularis), is still considered a rotator cuff tear.
Rotator Cuff Tears
How do you know it is a full thickness tear?
You will have high T2 signal in the expected location o f the tendon. On T1 you will have Gad in the bursa.
Adhesive Capsulitis “Frozen Shoulder”
overview
An inflammatory condition characterized by a global decrease in motion. You can have primary types, but a multiple choice key would be a history o f trauma or surgery.
It most commonly effects the rotator cu ff interval - and that is the most likely spot they will show it. The classic look is a T1 (or non-fat sat T2) in the sagittal plane showing loss o f fa t in the rotator c a ff interval (the spot with the biceps tendon - between the Supra S,and the Sub Scap).
Adhesive Capsulitis “Frozen Shoulder”
buzz1
‘Decreased Glenohumeral Volume ” - with injection
Adhesive Capsulitis “Frozen Shoulder”
buzz2
** Remember in Multi-Directional Instability the volume was increased.
Adhesive Capsulitis “Frozen Shoulder”
buzz3
“Thickened inferior a n d Posterior Capsule ”
Adhesive Capsulitis “Frozen Shoulder”
buzz4
“Enhancement o f the Rotator C u ff Interval - Post gad
SLAP
overview
Labral tears favor the superior margin and track anterior to posterior. As this tear involves the labrum at the insertion o f the long head o f the biceps , injury to this tendon is associated and part o f the grading system (type 4).
SLAP
things to know
When the SLAP extends into the biceps anchor (type 4), the surgical management changes from a debridement to a debridement + biceps tenodesis.
The mechanism is usually an over-head movement (classic = swimmer)
People over 40 usually have associated Rotator Cuff Tears
NOT associated with Instab ility (usually)
SLAP
mimic 1
The sublabral recess
This is essentially a normal variant where you have incomplete attachment o f the labrum at 12 o’clock. The 12 o’clock position on the labrum has the shittiest blood flow - that’s why you see injury there and all these developmentvariants.
SLAP
mimic 2
The Sublabral Foramen
- This is an unattached (but present) portion o f the labrum - located at the anterior-superior labrum (1 o’clock to 3 o ’clock).
As a rule it should NOT extend below the equator (3 o’clock position).
SLAP
mimic 3
The Buford Complex - A commonly tested (and not infrequently seen) variant is the Buford Complex. It’s present in about 1% o f the general population. This consists o f an absent anterior/superior labrum (1 o’clock to 3 o ’clock), along with a thickened middle glenohumeral ligament.
Buford complex
- Thick Middle GH Ligament
- Absent Anterior Superior Labrum
sublabral recess
Follows contour of glenoid
smooth margin
located at biceps anchor
B a n k a r t L e s io n s
list
Anterior dislocation injuries
GLAD Perthes ALPSA Bankart - cartilaginous Bankart (Osseous)
GLAD
Glenolabral Articular Disruption. It’s the most mild version, and it’s basically a superficial anterior inferior labral tear with associated articular cartilage damage (“ impaction injury with cartilage defect”). Not typically seen in patients with underlying laxity. It’s common in sports. No instability (a ren’tyou GLAD there is no instability)
Perthes
Detachment o f the anteroinferior labrum (3-6 o’clock) with medially stripped looks but intact periosteum.
Memory Aid:
-The detached
labrum sorta like a P
ALPSA
Anterior Labral Periosteal Sleeve Avulsion. Medially displaced labroligamentous complex with absence o f the labrum on the glenoid rim. Intact periosteum. It scars down to glenoid.
True bankart
Can be cartilaginous or osseous. The periosteum is disrupted. There is often an associated Hill Sach’s fracture.
GLAD quick
superficial partial labral injury
no instability
Perthes quick
Avulsed anterior labrum (only minimally displaced)
inferior GH complex still attached to periosteum
intact periosteum (lifted up)
ALPSA quick
similar to perthes but with bunhced up and medially displaced inferior GH complex
True bankart quick
torn labrum
periosteum disruption
P o s te rio r G len o h um e ra l In s ta b ility
overview
As I mentioned previously, anterior shoulder dislocations are way more common than posterior
shoulder dislocations. Therefore the Bankart, ALPSA, Perthes, e tc … are the ones you typically
think o f as the stigmata o f prior dislocation.
However, all that shit can happen in reverse with a posterior dislocation.
P o s te rio r G len o h um e ra l In s ta b ility
list
reverse osseous bankart
polpsa
bennett lesion
kims lesion
Reverse osseous bankart
A fracture o f the posterior inferior
rim o f the glenoid.
POLPSA
This is the bizarro version o f the
ALPSA, where the posterior labrum and
the posterior scapular periosteum (still intact) are stripped from the glenoid resulting in a recess that communicates with the joint space.
Bennett lesion
An extra-articular curvilinear calcification - associated with posterior labral tears tmavbe the POLPSA). It’s related to injury o f the posterior band o f the inferior glenohumeral ligament.
Kims lesion
An incompletely avulsed / flattened / mashed posteriorinferior labrum.
A key (testable) point is the glenoid cartilage and posterior labrum relationship is preserved.
HAGL
A non-Bankart lesion that is frequently tested is the HAGL (Humeral avulsion glenohumeral ligament). This is an avulsion o f the inferior glenohumeral ligament, and is most often the result o f an anterior shoulder dislocation (just like all the above bankarts). The “J Sign” occurs when the normal U-shaped inferior glenohumeral recess is retracted away from the humerus, appearing as a J.
S u b lu x a tio n o f th e B ic ep s Tendon
overview
The subscapularis attaches to the lesser tuberosity. It sends a few fibers across the bicipital groove to the greater tuberosity , which is called the “transverse ligament”. A tear o f the subscapularis opens these fibers up and allows the biceps to dislocate (usually medial). Subscapularis Tear = Medial Dislocation of the Long Head of the Biceps Tendon.
S u b lu x a tio n o f th e B ic ep s Tendon
subscap tendon
Forming portions of the “Transverse Ligament” that holds the biceps tendon in the groove
S u b lu x a tio n o f th e B ic ep s Tendon
quick
Occurs with a Tear of the Subscapularis
S u p ra s c a p u la r N o tch vs Sp in o g len o id N o tch
A cyst at the level o f the suprascapular notch will affect the supraspinatus and the infraspinatus. At the level o f the spinoglenoid notch, it will only affect the infraspinatus.
Q u a d rila te ra l S p a c e Syndrome
Compression o f the Axillary Nerve in the Quadrilateral Space (usually from fibrotic bands). They will likely show this with atrophy of the teres minor. Another classic question is to name the borders o f the quadrilateral space: Teres Minor Above, Teres Major Below, Humeral neck lateral, and Triceps medial.
P a rso n a g e -T u rn e r Syndrome
This is an idiopathic involvement o f the brachial plexus. Think about this when you see muscles affected by pathology in two or more nerve distributions (suprascapular and axillary etc..).
Fem ora l S h a ft F ra c tu re s
medial side
On the inside (medial) is the classic stress fracture location
Fem ora l S h a ft F ra c tu re s
lateral side
On the outside (lateral) is the classic bisphosphonate related fx location.
As shown in the image, you see cortical thickening (white arrow) along the lateral femur, eventually progressing into a fracture.
Hip fracture/dislocation
overview
You see these with dash board injuries. The posterior dislocation (almost always associated with a fracture as it’s driven backwards) is much more common than the anterior dislocation.
Hip fracture/dislocation
iliopectineal line
anterior
Hip fracture/dislocation
anterio column vs posterior column
The both column fracture by definition divides the ilium proximal to the hip joint, so you have no articular surface o f the hip attached to the axial skeleton (that’s a problem).
Hip fracture/dislocation
hip fx leading to avn
The location o f the fracture may predispose to AVN. It’s important to remember that, since the femoral head gets vascular flow from the circumflex femorals, a displaced intracapsular fracture could disrupt this blood supply - leading to AVN.
Testable Point: Degree o f fracture displacement corresponds with risk o f AVN.
Hip fracture/dislocation
corona mortis
The anastomosis o f the inferior epigastric and obturator vessels sometimes rides on the superior pubic ramus. During a lateral dissection - sometimes used to repair a hip fracture - this can be injured. 1 talk about this more in the vascular chapter.
Hip fracture/dislocation
hip fx leading to avn
The location o f the fracture may predispose to AVN. It’s important to remember that, since the femoral head gets vascular flow from the circumflex femorals, a displaced intracapsular fracture could disrupt this blood supply - leading to AVN.
Testable Point: Degree o f fracture displacement corresponds with risk o f AVN.
Avulsion In jury :
Hip overview
This is seen more in kids than adults. Adult bones are stronger than their tendons. In kids it’s the other way around. One pearl is that if you see an isolated “ avulsion” of the lesser trochanter in a seemingly mild trauma / injury in an adult - query a pathologic fracture. Now, to discuss what 1 believe to be one o f the highest yield topics in MSK, “where d id the avulsion come from? ”
The easiest way to show this is a plain film pelvis (or MRI) with a tug/avulsion injury to one o f the muscular attachment sites. The question will most likely be “what attaches there? ” or “which muscle got avulsed? ”
Muscle that originates
iliac crest
abdominal muscles
Muscle that originates
asis
sartorius TFL
Muscle that originates
AIIS
rectus femoris
Muscle that originates
greater trochanter
Gluteal muscles
Muscle that originates
lesser trochanter
iliopsoas
Muscle that originates
ischial tuberosity
hamstrings
Muscle that originates
pubic symphysis
adductor group
Snapping Hip Syndrome
steps
Clinical Eval for the “E x tern a l Type”
(IT band “snapping” over the Greater Trochanter)
This is to evaluate for the “In tra-Articular Type”
Looking for Hip Degen / Loose Bodies, Etc Radiographs?
IF NO Degen NEXT S T EP = Ultrasound
This is to look for the “In te rn a l Type”
Look for Dynamic “Snapping” o f the
Iliopsoas over the Uiopectineal eminence or femoral head
*This has to he shown with a CINE - because the finding is a dynamic moving o f a tendon I f yo u see a hip ultrasound fo r snapping - this is what they are going fo r
IF US Negative NEXT S T EP = MRI Arthrogram
This is to evaluate for the “Intra-Articular Type” … Again
This time looking for Labral Tears
Snapping Hip Syndrome
trivia
clinical sensation they have to tell you the pt feels snapping
Snapping Hip Syndrome
types
- External (most common) = Iliotibial Band over Greater Trochanter
- Internal = Iliopsoas over Uiopectineal eminence or femoral head
- Intra-Articular = Labral tears / jo in t bodies
Snapping Hip Syndrome
types
- External (most common) = Iliotibial Band over Greater Trochanter
- Internal = Iliopsoas over Uiopectineal eminence or femoral head
- Intra-Articular = Labral tears / jo in t bodies
IT Band Syndrome
This is a repetitive stress syndrome seen most classically in runners. The key finding is fluid on both sides of the IT band, extending posterior and lateral.
Fluid in the joint does not exclude the diagnosis, but for the purpose of multiple choice if you see fluid around the band and none in the joint you can be fairly certain this is the pathology the question writer is after.
Hip Labrum
what to know
1: Anterior-Superior Tears (white arrows) are by far the most common.
2: Paralabral Cysts (black arrow) are associated with tears and likely a hint that a tear is present.
3: Just like a shoulder intra-articular contrast will increase your sensitivity.
Ilio p so a s Bursa
overview
- Largest bursa o f the entire body.
- Communicates with the joint in 15% o f the population
- Seen Anterior to the hip
- Trivia: The illiospsoas tendon runs anterior to the labrum on axial and can mimic a tear.
Ilio p so a s Bursa
gamesmanship
A fluid signal “mass” with anterior to the femur (adjacent to the psoas tendon) at the level of the ischial tuberosity is likely Iliopsoas Bursitis
F em o ro a c e ta b u la r Im p in g em e n t (FAI):
overview
This is a syndrome of painful hip movement.
It’s based on hip / femoral deformities, and honestly might be total BS. Supposedly it can lead to early
degenerative changes. There arc two described subtypes: (A) Cam and (B) Pincher (technically there is a
mixed type - but I anticipate multiple choice to make it more black and white).
F em o ro a c e ta b u la r Im p in g em e n t (FAI):
memory aid
I remember that the femoral one (cam-type)
is more common in men because the femoral
head kinda looks like a penis.
Be honest, you were thinking that too.
F em o ro a c e ta b u la r Im p in g em e n t (FAI):
cam type
This is an osseous “bump” along the femoral head-neck junction.
F em o ro a c e ta b u la r Im p in g em e n t (FAI):
pincer type
Whereas the CAM type is a deformity of the femur, the pincer type represents a deformity of
the acetabulum. Whereas the CAM type is more common in a young athletic male, the pincer is more
common in a middle aged woman (insert sexist joke here).
F em o ro a c e ta b u la r Im p in g em e n t (FAI):
coxa profunda
acetabulu projects medial to the ilioschial line
F em o ro a c e ta b u la r Im p in g em e n t (FAI):
acetabular protrusion
Femur projects medial to the ilioischial line
F em o ro a c e ta b u la r Im p in g em e n t (FAI):
os acetabuli
This is an unfused secondary >=> ossification center. It’s actually normal in kids (should fuse by adult hood). It has several testable associations including FAI and Labral Tears
FAI
classic way to ask
The most classic way to show or ask this is the so-called
“cross over sign”, where the acetabulum is malformed -
causing the posterior lip to “Cross over” the anterior lip. A
Key point is that the coccyx needs to be centered at the
symphysis pubis to even evaluate this (rotation fucks things
up).
The other associated finding) s) of the pincer subtype worth
knowing are the acetabular over coverage buzzwords
(Coxa Profunda and Protrusio), and the Ischial Spine Sign:
Total Hip Arthroplasty
bone remodeling/stress shielding
The stress is transferred through the metallic stem, so the bone around it is not loaded. Orthopods call this “Wolff’s Law’ - where the unloaded bone just gets resorbed.
Happens more with uncemented arthroplasty. To some degree this is a normal finding - but when advanced can predispose to fracture.
Total Hip Arthroplasty
asymptomatic complications
- Stress Shielding
* Aggressive Granulomatosis
Total Hip Arthroplasty
proximal stress shielding
Proximal stress shielding -greater trochanter bone resorption
Total Hip Arthroplasty
distal stress loading
Distal stress loading: cortical thickening & pedestral (around the bottom)
“Zone 4“
Total Hip Arthroplasty
heterotopic ossifications
This is very common (15-50%). It’s usually asymptomatic. The trivia regarding multiple choice tests is that “hip stiffness” is the most common complaint. Also in Ank Spon patients, because they are so prone to heterotopic ossifications, they sometimes give them low dose prophylactic radiation prior to THA.
Total Hip Arthroplasty
aseptic loosening
This is the most common indication for revision. The criteria on x-ray is > 2 mm at the interface (suggestive). If you see migration of the component, you can call it (migration includes varus tilting o f the femora! stem).
Total Hip Arthroplasty
subsidence
Basically an arthroplasty
that is sliding downward. This is a described reason for early failure of THA. You see this most often in
arthroplasty implants without a collar.
Greater than 1 cm along the femoral component, or
progression after 2 years are indications of loosening.
Total Hip Arthroplasty
wear patterns
It is normal to have a little bit of thinning in the area of weight bearing - this is called “Creep.” It is not normal to see wear along the superior lateral aspect.
• Wear = Pathologic
• Creep = Normal
Total Hip Arthroplasty
particle diseaase
(Aggressive Granulomatosis): Any component of the device that sheds will
cause an inflammatory response. The more wear that occurs the more particles — wear is the
primary underlying factor. Macrophages will try and eat the particles and spew enzymes all over
the place. This process can cause progressive lytic focal regions around the replacement and joint
effusions.
Total Hip Arthroplasty
things to know about particle disease
Most commonly seen in non-cementcd hips
Tends to occur 1 -5 years after surgery — “late complication”
X-ray shows “smooth” endosteal scalloping (distinguishes from infection)
Aseptic - ESR & CRP will be normal
Produces no secondary bone response — no sclerosis
Can be seen around screw holes (particles are transmitted around screws)
Total Hip Arthroplasty
particle disease steps
wear > particle disease > osteolysis
Sacrum
overview
You can get fractures o f the sacrum in the setting o f trauma, but if you get shown or asked anything about the sacrum it’s going to be either (a) SI degenerative change - discussed later, (b) unilateral SI infection, (c) a chordoma - discussed later, (d) sacral agenesis, or (e) an insufficiency fracture. Out o f these 5 things, the insufficiency fracture is probably the most likely.
Sacrum
insuffieciency fx
The most common cause is postmenopausal osteoporosis. You can also see this in patients with renal failure, patients with RA, pelvic radiation, mechanical changes after hip arthroplasty, or extended steroid use. They are often (usually) occult on plain films.
Sacrum
insufficiency fx imaging
They will have to show this either with a bone V
scan, or MRI. The classic “Honda Sign” from the
“H” -shaped appearance is probably the most likely presentation on a mult,pie choice test.
Segond F ra c tu re :
This is a fracture o f the Lateral Tibial Plateau (icommon distractor is medial tibia). The thing to
know is that it is associated with ACL tear (75%), and occurs with internal rotation.
reverse segond fx
This is a fracture of the Medial Tibial Plateau. The thing to know is that it is associated with a PCL tear, and occurs with external rotation. There is also an associated medial meniscus injury.
arcuate sign
This is an avulsion o f proximal fibula (insertion of arcuate ligament complex). The thing to know is that 90% are associated with cruciate ligament injury (usually PCL)
deep intercondular notch sign
This is a depression of the lateral femoral condyle (terminal sulcus) that occurs secondary to an impaction injury. This is associated with ACL tears.
ACL anatomy
Composed of two bundles (anteromedial & posterolateral). The tibial attachment is thicker then the femoral attachment. Both the ACL and PCL are intra-articular and extrasynovial.
PCL anatomy
The strongest ligament in the knee (you don’t want a posterior dislocation of your knee resulting in dissection of your popliteal artery).
MCL anatomy
The MCL fibers arc laced into the joint capsule at the level of the joint, with connection to the medial meniscus. Unlike the ACL and PCL, the MCL is an extra-articular structure.
Conjoint tendon anatomy
Formed by the biceps femoris
tendon and the LCL.
ACL and PCL overview
ACL & PCL are extrasynovial and intraarticular. The synovium folds around the ligaments. This is why a tom ACL won’t heal on its own (usually). The ligament can be tom even if the synovium is intact - this is why the “taunt” angle of the ligament is a key feature of integrity - more on that later
IT band inserts on
Gerdys tubercle
M a g ic A n g le Phenomeno n
The PCL and Patellar tendon may have foci o f intermediate signal intensity on sagittal images with short echo time (TE) sequences where the tendon forms an angle o f 55 degrees with the main magnetic field (magic angle p h en omen o n ).
This will NOT be seen on T2 sequences (with long TE). This phenomenon is reduced at higher field strengths due to greater shortening o f T2 relaxation times.
M a g ic A n g le Phenomeno n
quick
You sec it on short TE sequences (Tl, PD, GRE). It goes away on T2
ACL T e a r:
overview
- Associated with Segond Fracture (lateral tibial plateau) and tibial spine avulsion
- ACL Angle lesser than Blumensaat’s Line
- O’donoghue’s Unhappy Triad: ACL Tear, MCL Tear, Medial Meniscal Tear
- Classic Kissing Contusion Pattern: The lateral femoral condyle (sulcus terminals) bangs into the posterior lateral tibial plateau. This is 95% specific in adults.
- Anterior Drawer Sign = Ortho Physical Exam Finding suggesting ACL Tear.
ACL Mucoid D e g e n e ra tio n
This can mimic acute or chronic partial tear of the ACL. There will be no secondary signs of injury (contusion etc..). It predisposes to ACL ganglion cysts, and they are usually seen together. The T2/STIR buzzword is “celery stalk” because o f the striated look. T h eT l buzzword is “drumstick” because it looks like a
drum stick.
ACL repair
ACL can be repaired with two primary methods. Method 1: Using the middle one-third of the
patellar tendon, with the patella bone plug attached to one end and tibial bone plug attached at the
other. Method 2: Using a graft made of the semitendinosus or gracilis tendon, or both. The graft is
then attached with all sorts of screws, bolts, etc… There is a lower reported morbidity related to
harvest site using this method.
ACL Graft evaluation
tibial tunnel
Should parallel the roof of the femoral intercondylar notch. Too Steep = Impinged by femur on extension. Too Flat = Lax & won’t provide stability. Too Far Anterior (“Intersection with Blumensaat line”) = Can lead to pinching at the anterior inferior Normal intercondylar root. Buzzword Root Impingement.
ACL Graft evaluation
femoral tunnel
Supposedly the primary factor for maintaining length and tension during range of motion. This is referred to as “maintained isometry.”
ACL Graft evaluation
arthrofibrosis
Can be focal or diffuse (focal is more common). The focal form is the so called “Cyclops” lesion - so named because of its arthroscopic appearance. It’s gonna be a low signal
mass-like scar in Hoffa’s fat pad. It’s bad because it limits extension.
Buzzword “palpable audible clunk”
Seen around 16 weeks - it obviously won’t occur immediately post op because you have to build up your scar.
ACL Graft evaluation
cyclops lesion
scar associated with ventral graft
ACL Graft evaluation
trivia 1
The graft is most susceptible to tear in the remodeling process (4-8 months post op).
ACL Graft evaluation
trivia 2
Other signs of graft tear: grossly high T2 signal (some is ok), fiber discontinuity, uncovering of the posterior horn of the lateral meniscus (secondary sign), anterior tibial translation (secondary sign).
ACL Graft evaluation
Graft teat
Usually Ortho can just pull on his fucking leg is see if the graft is trashed (anterior drawer sign). For imaging, the simple way to understand this: “flat angle = tear. The ACL should parallel the roof of the intercondylar notch. If the angle becomes flat, a tear is likely.
Femoral Tunnel =
Tibial Tunnel =
1 maintains isometry
2 roof impingement
o s te rio r L a te ra l C o rn e r (PLC):
The most complicated anatomy in the entire body. My God this posterior lateral corner! Just think about the LCL, the IT band, the biceps femoris, and the popliteus tendon. The most likely way to show this on a single image (multiple choice style) is edema in the fibular head.
Who cares? Missed PLC injury is a very common cause o f ACL reconstruction failure.
PCL Tear overview
The posterior collateral ligament is the strongest ligament in the knee. A tear is actually uncommon, it’s more likely to stretch and appear thickened ( > 7 mm). PCL tears should make you think about posterior dislocation as the mechanism o f injury..
PCL tear next step/association
If you see a PCL Tear - look at the popliteal flow void. If the knee dislocated posterior, a dreaded consequence is vascular compromise. Depending on the wording o f the question they might need a run-off (watch your back).
Meniscal anatomy
The meniscus is “C shaped”, thick along the periphery and thin centrally.
Medial meniscus is thicker posteriorly.
Lateral meniscus has equal thickness between anterior and posterior portion.
Meniscal healing
The Peripheral “Red Zone” is vascular and might heal.
The Central “white zone” is avascular and will not heal. The blood supply comes from the geniculate arteries (which enter peripherally).
Meniscal tears
overview
As stated, the peripheral meniscus (red zone) has better vasculature than the inner 2/3s (white zone) and
might heal on its own. In general, you can group tears based on their general direction (as seen on a
sagittal section MRI - i.e. the triangles and bowties) - as either vertical (top-to-bottom) or horizontal
(front-to-back). You can then sub-group them depending how they look on subsequent sections.
Meniscal tears
radial tear
- Bad because they cause “loss of hoop strength.” - Can lead to extrusion, early OA etc..
Radial Tearing Cuts the Circular Hoop Fibers that Hold the Meniscus Together
Meniscal tears
flap tear (parrot beak)
Radial Tear that Changes
Direction into the
longitudinal direction
Meniscal tears
longitudinal tear
Can be vertical or horizontal (or mixed oblique patterns) - Defined by a long extension in the axial direction - Vertical Types can flip (bucket- handle)
Meniscal tears
horizontal cleavage tear
- Pure cleavage tears extend to the apex - Associated with Meniscal Cysts - Most common in posterior horn of the medial meniscus
Meniscal tears
radial tear classic signs
usually 2 are present
truncated triangle
cleft (most reliable)
ghost or absent triangle
Meniscal tears
bucket handle tear
This is a tom meniscus (usually medial -
80%) vertical longitudinal sub-type, that flips
medially to lie anterior to the PCL.
Meniscal tears
bucket handle tear gamesmanship
Most likely shown as the
classic Aunt Minnie appearance of a “double PCL.”
Can also be shown as “not enough bowties,” the opposite of the “too
many bowties” look of a discoid meniscus.
Only 1 bowtie -
instead o f the normal 2. The m iddle o f the second bowtie is flipped medially.
Meniscal tears
bucket handle trivia
The appearance of a double PCL can
only occur in the setting of an intact ACL,
otherwise it won’t flip that way. Just know it
sorta indirectly proves the ACL is intact (I
can just see some knucklehead asking that).
Meniscal tears
discoid meniscus gamesmanship 1
“Pediatric Patient with Meniscal
Tear”.
Meniscal tears
discoid meniscus gamesmanship 2
If shown on sagittal
they have to show you 3 or more “bow ties” /
double triangles.
Meniscal tears
discoid meniscus bow ties
Normal Meniscus will have 2 bowtie shapes in the
sagittal plane - assuming 3mm slices with 1mm
gap-
Discoid Meniscus will have 3 or more bowties
Meniscal tears
discoid meniscus gamesmanship 3
If shown on coronal they need to show you a meniscus stretching into the notch.
Discoid meniscus trivia
There are three types, with the most rare
and most prone to injury being the Wrisberg
Variant.
Discoid meniscus trivia
There are three types, with the most rare
and most prone to injury being the Wrisberg
Variant.
Meniscal cysts
Most often seen near the lateral meniscus and are often associated with horizontal cleavage tears.
Bakers Cyst
Occurs between the
semimembranosus and the
MEDIAL head o f the gastroc
M e n is c o c a p s u la r S e p a ra tio n
This is a rare (in real life - maybe not on exams) injury. The idea is that the deepest layer o f the MCL complex (capsular ligament) is relatively weak and is the first to tear. This deep tearing may result in the separation o f the meniscus and the MCL. I’ve never seen it occur in isolation (theoretically it can). The important things to remember are probably (1) it happens more with proximal MCL tears, and (2) this is a serious injury — requires immobilization or surgery.
M en is c a l Ossicle
This is a focal ossification o f the posterior horn o f the medial meniscus, that can be secondary to trauma or simply developmental. They are often associated with radial root tears.
Meniscofemoral ligaments
There are 2 (Wrisberg, Humphry) which can be mimics o f meniscal tears. Wrisberg is in the back ( “humping H um p h ry”). You could also remember that “H” comes before “W” in the alphabet.
Meniscal flounce
This an uncommon finding o f a “ ru ffled ”
appearance o f the meniscus that mimics a tear.
It’s NOT associated with an increased incidence o f
tear - but can look like one, if you don’t have any
idea what one looks like.
Patella Dislocation:
overview
Dislocation o f the patella is usually lateral
because o f the shape o f the patella and femur.
The contusion pattern is classic.
Patella Dislocation:
points
• It’s Lateral • Contusion Pattern - Classic •Associated tear o f the MPFL (medial patellar femoral ligament) •Associated with “Trochlear Dysplasia ” - the trochlea is too flat.
P a te lla A lta / Baja
The patella will move up or down in certain traumatic situations. If the quadricep tendonmtears you will get unopposed pull from the
patellar tendon resulting in a low patella (Baja). If the patella tendon tears you will get unopposed quadriceps tendon pull resulting in
a high patella (Alta).
The “classic” association with patellar tendon tear (Alta) is SLE, (also can see in elderly,trauma, athletics, or RA).
bilateral patellar rupture is a buzzword for
chronic steroids
Prepatellar
Bursitis
fluid superficial to the patella
fat impingement syndrome
high T2 signal in hoffas fat ingerior to the patella
jumpers knee
high t2 signal + thickening of the inferior patella
Tib ia l P la te a u F ra c tu re
This injury most commonly occurs from axial loading (falling and landing on a straight leg). The lateral plateau is way more common than the medial. If you see medial, it’s usually with lateral. Some dude named Schatzker managed to get the classification system named after him, o f which type 2 is the most common (split and depressed lateral plateau).
pilon fx (tibial plafond)
This injury also most commonly occurs from axial loading, with the talus being driven into the tibial plafond. The fracture is characterized by comminution and articular
impaction. About 75% o f the time you are going to have fracture o f the distal
fibula.
tibial shaft fx
This is the most common long bone fracture. It was also listed as the most highly tested subject in orthopedic OITE exam (with regard to trauma), over the last 8 years. Apparently there are a bunch o f ways to put a nail or plate in it. It doesn’t seem like it could be that high yield for the CORE compared to other fractures with French or Latin sounding names. I will point out that the tibia is one o f the slowest healing bones in the body (10 weeks).
Tillaux fx
overview
This a Salter-Harris 3,
through the anterolateral aspect o f the distal tibial
epiphysis.
Tillaux fx
trivia 1
This pattern requires an open physis along the
lateral distal tibia. This is why you see this fracture
pattern in the window between the start o f medial
physis fusion and the complete fusion o f the lateral
physis (lateral physis typically closes around 12-15).
Tillaux fx
trivia 2
The distal tibial growth plate closes from
medial to lateral (medial first).
Triplane fx
This is a Salter-Harris
4, with a vertical component through the
epiphysis, horizontal component through the
physis, and oblique through the metaphysis.
*The addition o f the fracture plane in the
posterior distal tibial metaphysis (coronal plane)
distinguishes this from the Tillaux.
Maisonneuve fx
This is an unstable fracture involving the medial tibial malleolus and/or disruption of the distal tibiofibular syndesmosis.
The most common way to show this is to first show you the ankle with the widened mortis, and “next step? ” get you to ask for the proximal fibula - which will show the fracture o f the proximal fibular shaft.
This fracture pattern is unique as the forces begin distally in the tibiotalar jo in t and then ride up the syndesmosis to the proximal fibula.
Maisonneuve fx
trivia
does not extend ino the hindfoot
Maisonneuve
wide medial malleolus
(+/- Medial Malleolus Fracture)
— Distal Tibiofibular syndesmosis
+/- Deltoid Lig Injury^
maisonneuve
proximal fibular fx
— From upwardforce extension
( “the rippin an d the tearin ”) via the syndesmosis
Casanova fx
overview
If you see bilateral calcaneal fractures, you should “next s te p ? ” look
at the spine (T12-L2) for a compression or burst fracture. These tend to occur in axial loading
patterns (possibly from jumping out a window to avoid an angry husband).
Casanova fx
trivia
- Peroneal tendons can become entrapped with lateral calcaneal fractures.
- Calcaneal fractures are the most common (60%) Tarsal Bone Fx
- Fractures o f the calcaneus are either extra-articular or intra-articular - depends on subtalar jo in t involvement. Intra-articular fractures will have a fracture line through the “critical angle o f Gissane ”
Casanova fx
bohlers angle
The line drawn between the anterior and posterior borders o f the calcaneus on a lateral view. An angle less than 20 degrees, is concerning for a fracture.
Casanova fx
critical angle of gissane
“More Flat” (More than 130)
Equals Depression of the Posterior Facet
normal is 95-105
Stress fx of the 5th metatarsal
This is considered a high risk fracture (hard to heal).
Jones Fx
This is a fracture
at the base o f the fifth metatarsal, 1.5cm
distal to the tuberosity. These are placed
in a non-weight bearing cast (may
require internal fixation- because o f risk
o f non-union.
Avulson fracture of the 5th metatarsal
This is more common than a jones fracture. The classic history is a dancer. It may be secondary to tug from the lateral cord of the plantar aponeurosis or peroneus brevis (this is controversial).
Painful Os Peroneus S yndrom e (POPS)
*Os Peroneus (accessory ossicle) is within the Peroneus LONGUS
•This ossicle is seen in about 10% of gen pop
•Stress reaction and pain can progress to tendon disruption = POPS
Painful Os Peroneus S yndrom e (POPS)
key mr findings
Edema in the os peroneus just before the peroneus longus tendon enters the cuboid tunnel
L is fra n c In jury:
overview
This is the most common dislocation of the
foot. The Lisfranc joint is the articulation o f the tarsals and
metatarsal bases. This joint is recessed creating a “keystone”
locking mechanism, and would make a good place to amputate if
you were a surgeon assisting in the Napoleonic invasion o f
Russia. The Lisfranc ligament connects the medial cuneiform to
the 2nd metatarsal base on the plantar aspect.
L is fra n c In jury:
keys
- Can’t exclude it on a non-weight bearing film
- Associated fractures are most common at the base o f the 2nd MT - “Fleck Sign ”
- Fracture non-union and post traumatic arthritis are gonna occur if you miss it (plus a lawsuit).
L is fra n c In jury:
fleck sign
This is a small bony fragment
in the Lisfranc Space (between 1st MT and 2nd
MT) - that is associated with an avulsion o f the
LF ligament.
L is fra n c In jury:
mechanism
Extreme Plantar Flexion +
Axial Load
L is fra n c In jury:
ligaments
3 Ligaments make up the
complex between the
medial cuneiform and
2nd MT.
plantar band is the strongest
