(3) Lecture 15: Knee 2.0 Flashcards
Medial Support Complex Layers
3 layers
Superficial: Sartorius and fascia
Middle: superficial MCL and semimembranosus
Deep: deep fibres of MCL and capsule
Medial Support Complex Stability
Primary stabilizer: MCL - 25 to 30 degrees
- ACL/PCL secondary
Bony structure is tertiary support
Muscles help in full extension
- medial hamstrings (sartorius, semimemb, semitend.)
- medial head of gastrocs
- quad muscle - vastus med.
MCL Components
CAPSULAR = swelling
Has superficial and deep components
- deep: connect directly to medial meniscus
- superficial: run from medial femoral epicondyle to superomedial surface of tibia
Contribution by Structure to Medial Knee Injuries
AT 25 degrees
- most from superficial MCL then crucoiates
AT 5 degrees
- most from superficial MCL (less than at 25) then post capsule then cruciates
Anatomy of ACL
- runs from anterior aspect of tibial plateau to posterior medial aspect of lateral femoral condyle
2 major bundles named for attachment on tibia:
- anteromedial - tighter in FLEXION (heat-sensitive)
- posterolateral - tighter in EXTENSION
PRIMARY RESTRAINT TO ANTERIOR TIBIAL TRANSLATION
greatest translation at 20 - 30 degrees
Stabilizing role of ACL
WEAKER of two cruciates
- restricts POSTERIOR translation of FEMUR relative to tibia during WEIGHT BEARING
- restricts ANTERIOR translation of TIBIA during NON-weight bearing
- also limits excessive rotation of tibia
secondary support for VALGUS and VARUS w/ collateral lig. damage
Heat sensitive view of ACL
anteromedial bundle tightens in FLEXION
posterolateral bindle tightens in EXTENSION
WHITER = MORE ON STRETCH
Anatomy of PCL
- originates on lateral aspect of medial femoral condyle and inserts posteriorly to intercondylar area of tibia
2 major bundles named for attachment on tibia:
- anterolateral: tight in FLEXION (larger)
- posteromedial: tight in EXTENSION
LARGER AND STRONGER than ACL
- primary restraint to POSTERIOR tibial translation
- GREATEST translation at 20-30 degrees
Stabilizing role of PCL
STRONGER of cruciate ligs
- restricts anterior translation of femur relative to the tibia during weight beating (foot planted)
- restricts posterior translation of tibia during NON-weight bearing
- limited HYPER-INTERNAL ROTATION
- secondary support for valgus + varus w/ collateral lig damage
Collaterals supports
Lateral primary support = MUSCLES
Medial primary support = MCL
Meniscus
- once believed to be a useless remnant of intra-articular attachments
- stabilize knee by increasing concavity of tibia
Shock absorption
- full extension (45-50% of load)
- 90 degree flexion (85% of load)
- compression facilitates distribution of nutrients
Medial vs Lateral Meniscus
Medial Meniscus - LOTS of issues (more injured)
- C-shaped
- larger radius of curvature
- tight connection w/ capsule + MCL
- POOR MOBILITY
- ex. Tutanic
Lateral Meniscus - less injured but more CATASTROPHIC
- O shape
- smaller radius of curvature
- attached loosely to capsule + POPLITEAL TENDON
- increased mobility
- ex. speedboat
Meniscal Fixation
- menisci are fixed in place + prevented from extruding by CORONARY ligaments and anterior + posterior transverse meniscal ligaments
- deep portion of capsule attached to periphery of mensicus
- medial is THICKER/TIGHTER than lateral
Meniscal Blood Flow
Divided into 3 zones:
- RED zone: good blood supply - outer 1/3
- RED-WHITE zone: minimal blood supply - middle 1/3
- WHITE zone: avascular
Outer injuries heal better b/c of good blood flow
Inner injuries are usually cut out b/c they won’t heal
Subjective Knee Assessment
Area of pain - medial, lateral, internal?
Mechanism of Injury
- Varus or Valgus (valgus: hit on outside + stretch inside)
- Contact or non-contact (if non-contact: decelerating, cutting, landing?)
Sounds (i.e. “pop” or “crack”)
Continue to play/able to weight bear (WB)?
Locking (meniscal), giving way since (ligamentous, muscle, etc)
Knee Swelling - Subjective Assessment
Nature of swelling - hemarthrosis?
Noticeable swelling 2-6 hours post-injury
- >75% of adults - ACL tear
- Young (13-14) most common is patellar dislocation
- Pediatrics - suspect patellar dislocation
Hemarthrosis
Fast swelling
- bleeding into joint
- typically occurs more quickly than synovial effusion/capsular swelling
Ex. ACL, red-red mensicus, patellar dislocation
Ottawa Knee Rules
Knee X-Ray is ONLY needed for knee injuries w/ any of these findings:
- age 55 or older
- isolated tenderness of patella (no other bone tenderness)
- tenderness of head of fibula (2-3 in. lateral from tib. tuberosity)
- cannot flex to 90 degrees
- unable to bear weight for 4 STEPS (unable to TRANSFER WEIGHT TWICE onto each lower limb regardless of limping)
Subluxed or Dislocated Patella
generally dislocates LATERALLY
Acute Patellar Dislocation MOI
- forceful knee rotation (tibia ER/femur IR) +/- forceful quad contraction
- knee usually near full extension (out of trochlea) - patella moves UP in extension
+/- laterally directed force
Symptoms of Patellar Dislocation
- may report feeling knee “shift”, “move” or “pop out”
- LOTS OF PAIN UNTIL REDUCED
- FAST swelling = hemarthrosis
Signs of Patellar Dislocation
- loss of knee function (if still dislocated)
- tenderness over MEDIAL border of patella
- POSITIVE LATERAL APPREHENSION TEST
NEED TO R/O ACL –> b/c of similar subjective findings - hemarthrosis, shift/move/pop
Patellar Dislocation Treatment
Slightly FLEX HIP and slowly EXTEND THE KNEE
- takes tension off quads - easier to reduce
- usually patella relocates. If not, do NOT force the patella medial
send for X-rays immediately
Lateral Support Complex
3 layers
Superficial: ITB and biceps femoris
Middle: patellofemoral ligs and retinaculum
Deep:
- LCL
- popliteus tendon
- capsule
MAIN SUPPORT FROM MUSCLES
LCL
- injuries are less common but more complicated
- usually VARUS (force on medial side) loading +/ hyperextension
- most contribution at 20-30 degrees of knee FLEXION
- may include ITB, lateral hamstrings and/or popliteus
Varus force vs valgus loading
Varus loading - force on medial side
Valgus: hit on outside + stretch inside
MCL Facts
- 40% of all severe knee injuries involve MCL
- MOST FREQUENTLY INJURED knee structure
- VALGUS force +/- rotation
- often occurs in ISOLATION (unlike lateral)
Signs and symptoms of collateral ligament sprains
reports of pain over structure
Swelling? Timing?
- slow localized swelling on medial side (grade 2+) – capsular effusion > 8 hrs
Stress testing: in SAME DIRECTION of MOI
- valgus stress for MCL and varus stress for LCL
- Grade 1: pain w/ no laxity
- Grade 2: pain w/ laxity; distinct endpoint
- Grade 3: pain variable; gross laxity; no endpoint
ACL injuries
- can be contact or non contact (60-80% non-contact)
usually during cutting or single leg landing
- may occur in isolation or in combo w/ other injury (75% have meniscal injury; 80% have bone bruise on lateral jt line or Segond Fracture)
2-8x higher injury rate in females
ACL MOI
- Valgus after MCL - usually w/ contact
- Deceleration/internal rotation - non-contact
- Quads Active - anterior tibial translation (quads fire more than hamstrings - more common in FEMALES)
NOT hyperextension - doesn’t happen in isolation
Quads Active ACL MOI
no co-contraction from hamstrings
Main mechanisms
- rapid deceleration
- untoward landing
anterior tibial dislocation by quads
Symptoms of ACL injury
- 80% describe an audible “pop” or “crack”
- can range from very painful to minimal pain
- usually unable to continue activity
- HEMARTHROSIS (>75% –> 1-6 hours)
- may report instability or giving way
Signs of ACL injury
- restricted movement - especially extension
- lateral joint tenderness - often mistaken for LCL (80% have lateral bone bruise or Segond Fracture)
- POSITIVE ANTERIOR DRAWER + LACHMAN’S TEST (LACHMAN > ANT. DRAWER)
- Lachman @ 20-30 degrees of flexion
PCL Injuries
- STRONGEST of knee ligaments
- only 1 in 10 cruciate injuries involve PCL
- 60% include injuries to other structures
- usually sports injuries but also common in MVAs
PCL MOI
Most common: DIRECT BLOW to upper portion of tibia
- fall on flexed knee
- MVA - dashboard injury or pre-tibial trauma
Hyper-flexion
- increased tension in anterior segment
- impinged btwn posterior tibia + intracondylar notch roof
Hyperextension
Signs of PCL Injury
- MINIMAL swelling
- POSTERIOR DRAWER test = most sensitive
- SAG TEST will be positive
- assess medial and lateral structures too
Malalignment Syndromes/Overuse Knee Injuries/Patellofemoral Pain
- tendinosis
- osteoarthritis
- runner’s knee
- chondromalacia
- ITB friction syndrome
- Patellofemoral Pain Syndrome
- jumper’s knee
PFP
Patellofemoral Pain
- pain in peripatellar/retropatellar area that is aggravated by at least one activity that loads the patellofemoral jt during weight bearing on a flexed knee
- pain walking down stairs
- pain with squatting
- pain following sitting for long periods
- running, jumping, hopping
patients w/ PFPS are 10-25% of PT visits
Causes of PFP
- HYPO-pressure on medial aspect of patellofemoral jt
- HYPER-pressure on later aspect
- results in cartilage degeneration from inside-out
- results in cartilage rub and fibrillation
Proposed contributing INTRINSIC factors
- Lower chain alignment
- Excessive pronation
- Poor multi-plane lumbo-pelvic/pelvo femoral control (core, glut. medius)
- Shortened muscles: hamstrings, ITB, calves and rectus femoris
- Pull of quads
Lower Chain alignment and PFP
VALGUS alignment is common for PFP
Load bearing axis on outside = pushing in (knocked knees)
Q-Angle
- axis formed by femur and tibia
- greater Q angle = greater lateral pull
- Q angle > 20 degrees = increased risk of instability of PF jt
- can be factor in PFPS, OA, ITB friction syndrome (varus)
Medial Collapse Mechanism
poor multi-plane lumbo-pelvic/pelvo femoral control
- hip adduction, femoral internal rotation and knee valgus (lateral pull on patella)
change femur under patella
- less joint contact area
- more joint stress
Shortened muscles
Tight muscles crossing the knee may cause altered function
Quads, hamstrings, ITB, triceps surae
Shortened quads
increased compression of PF joint during physical actibity
Shortened hamstrings
antagonist to quads
will need increased quads force production to overcome length issue
Shortened ITB
lateral influence on patella = more pressure over lateral surface of trochlear groove
must move over femoral condyle at 25-30 degrees flexion
Shortened triceps surae
triceps surae: gastrocs + soleus
limit ankle dorsiflexion, which is often compensated for by excessive rotation of lower leg
- altered Q angle
Vastus medialis dysfunction
- sum of all 4 quads and tibial tendon are set into valgus
- theory that weak VMO will not be able to maintain alignment
causes abnormal pull on patella - overloading lateral side
PFP Treatment
Initial phase
- PEACE & LOVE/POLICE
- palliate pain, decrease swelling, identify training issues
Repair phase - correct biomechanical issues
- look at muscle length, strength and function
Remodeling phase
- slowly increase training frequency and intensity
Evidence Based Tips for PFP Rehab
- prescribe daily exercises of 2-4 sets of 10+ reps over a period of 6+ weeks
- consider higher reps for PFP patients who do lots of running and jumping
- conflicting research about knee braces and oatellar taping
- some evidence for prefabricated foot orthoses w/ regard to reducing short term pain
