PC Knee Flashcards
1
Q
Q angle
A
Angle btw line from ASIS to centre of patella to tibial tubercle
2
Q
J sign patella
A
excessive lateral translation in extension which “pops” into groove as the patella engages the trochlea early in flexion —-associated with patella alta
3
Q
Most sensitive test to detect combined ACL & MCL tear
A
Anterior drawer test with tibia in EXTERNAL rotatoin
4
Q
Segond sign
A
Small lateral tibial avulsion fracture that indicates a ACL tear
5
Q
Reverse Segond sign
A
Small medial tibial avulsion fracture that indicates a PCL tear
6
Q
Arcuate sign
A
Fibular head avulsion fracture that indicates a PLC injury
7
Q
Pellegrini Stieda sign
A
Medial femoral condyle avulsion fracture that indicates a chronic MCL injury
8
Q
Patella alta
A
Patellofemoral pathology
9
Q
Patella baja
A
Arthrofibrosis
10
Q
Fairbanks changes
A
DJD - post meniscectomy (square condyle, peak eminences, ridging, narrowing)
11
Q
Lateral MFC lesion
A
OCD
12
Q
Crescent-shaped MFC lesion
A
Spontaneous osteonecrosis of the knee (SONK)
13
Q
Square lateral femoral condyle, cupped lateral tibial plateau, hypoplastic lateral tibial spine
A
Discoid meniscus
14
Q
Main secondary stablizer to anterior translation of the tibia
A
Posterior horn of the medial meniscus
15
Q
Type of collagen and % in the meniscus
A
90% Type I collagen
16
Q
Ligamentous attachements of the menisci
A
– transverse (intermeniscal) ligament
connects the medial and lateral meniscus anteriorly
– coronary ligaments
connects the meniscus peripherally
medial meniscus has less mobility with more rigid peripheral fixation than the lateral meniscus
– meniscofemoral ligament
connects the meniscus into the substance of the PCL
originate from the posterior horn of the lateral meniscus and has two components
Humphrey ligament (anterior)
Ligament of Wrisberg (posterior)
17
Q
How to menisci heal?
A
Tears in peripheral 25% can heal
Heal via fibrocartilage scar
18
Q
Blood supply to meniscus:
A
Middle genicular artery — posterior horns of MM/LM
Medial inferior genicular a — peripheral MM
Lateral inferior genicular a –> peripheral LM
19
Q
Most sensitive test to detect meniscal tear
A
Joint line tenderness
20
Q
First line treatment for degenerative meniscal tear
A
Nonop
21
Q
Indications for partial meniscectomy
A
- tears not amenable to repair (complex, degenerative, radial tear patterns)
- repair failure >2 times
22
Q
Indications for meniscal repair
A
- peripheral tear
- lower rim width (distance at periphreal meniscocapsular junction)
- vertical or longitudinal tear
- small (1-4 mm in length)
- acute repair combined with ACL recon
23
Q
Indications for meniscal transplant
A
– young pts with near-total meniscectomy, especially lateral
24
Q
Contraindications for mensical transplantatoin
A
- inflammatory arthritis
- instability
- marked obesity
- grade IV chondrosis
- malalignment
- diffuse arthritis
25
Criteria for meniscal transplant
- - Age < 50
- - BMI < 30
- - Pain in the tibiofemoral joint
- - 2 mm or more in the tibiofemoral joint space on Rosenberg
- - Ligamentous stability
- - Normal alignment
- - No XR evidence of advanced arthrosis
26
Interval for inside-out MEDIAL meniscal repair
Incise sartorius fascia
Retract pes tendons/semimembranosus posteriorly
Develop plane btw the medial gastroc and capsule
** risk = saphenous vein and nerve **
27
Interval for inside-out LATERAL meniscal repair
Develop plane btw IT band and biceps tendon
Retract lateral head of gastroc posteriorly
** risk = peroneal nerve **
28
Best stitch type for fixation of mensical repairs
Vertical mattress sutures are strongest bc capture circumferential fibers
29
Most common complication after meniscal transplant
Mensical graft tear
30
Perimeniscal cyst (cyst within the meniscus)
Meniscal tear
31
Watanabe classification
Type 1 - Complete discoid meniscus
Type 2 - Incomplete discoid meniscus
Type 3 - Wrisberg (lack of posterior meniscotibial attachment to tibia) --- d/t hypermobility, higher risk for tears
32
XR findings in discoid meniscus
widened joint space (up to 11mm)
squaring of lateral condyle with cupping of lateral tibial plateau
hypoplastic lateral intercondylar spine
33
Treatment of discoid meniscus - asympotmatic
Observation
34
Indicatoins for surgery for discoid meniscus
- - pain and mechanical symptoms
| - - meniscal tear or meniscal detachment
35
Most common injury associated with ACL tear
Lateral meniscal tear (54%)
36
Female ACL injuries versus male ACL injuries
4. 5:1 F:M ratio
- - Antatomic: impingment, smaller ACL, hypermobility
- - Biomech: increased valgus/extension at landing, decreased knee/hip flexion, fatigue
- - Neuromusc: lower hamstring:quad radio (more quad dominant), weaker core stability
- - Hormonal
- - Genetic: collagen production
37
Anterior edge of ACL origin on femur
Lateral intercondylar ridge of femur
38
Line that separates anteromedial and posterolateral budle attachements of ACL on femur
Bifurcate ridge
39
ACL blood supply
Middle geniculate artery
40
Location of bone bruises in acute ACL tears
middle 1/3 of LFC (sulcus terminalis)
posterior 1/3 of the lateral tibial plateau
subchondral changes on MRI can persist years after injury
41
Indications for ACL reconstruction
- - younger, more active patients (reduces the incidence of meniscal or chondral injury)
- - children (strongly consider operative as activity limitation is not realistic)
- - older active patients (age >40 is not a contraindication if high demand athlete)
- - prior ACL reconstruction failure
42
Timing of treatment in ACL with MCL injury
allow MCL to heal (varus/valgus stability) and then perform ACL reconstruction
varus/valgus instability can jeopardize graft
43
Timing of treatment in ACL with meniscal tear
- - perform the meniscal repair at the same time as ACL reconstruction
- - increased meniscal healing rate when repaired at the same time as ACL
44
Timing of treatment of ACL with posterolateral corner injury
-- reconstruct at the same time as ACL or as 1st stage of 2 stage reconstruction
45
Location of ACL tibial tunnel placement
10-11mm in front of the anterior border of PCL insertion
6mm anterior to the median eminence
9mm posterior to the inter-meniscal ligamen
46
Pros/cons of bone-patellar-bone autograft for ACL reconstruction
- - the longest history of use and considered the "gold standard"
- - bone to bone healing
- - ability to rigidly fix the joint line (screws)
- - the highest incidence of anterior knee pain (up to 10-30%)
- - maximum load to failure is 2600 Newtons (intact ACL is 1725 Newtons)
47
Complications in BTB ACL reconstruction
Patella fracture
Patellar tendon rupture
Re-rupture (associated with age < 20 and graft size < 8mm)
48
Pros/cons of hamstring autograft for ACL reconstruction
- - smaller incision, less perioperative pain, less anterior knee pain
- - fixation strength may be less than Bone-PT-Bone
- - maximum load to failure is approximately 4000 Newtons
- - decreased peak flexion strength at 3 years compared to Bone-PT-Bone
- - concern about hamstring weakness in female athletes leading to increased risk of re-rupture
49
Best determinant of skeletal maturity in females
Menarche
50
Factors that lead to physeal injury during pediatric ACL reconstruction
- - large tunnel diameter (>12mm) is most important
- - 8mm tunnel corresponds to <3% physeal cross-sectional area
- - 12mm tunnel corresponds to >7-9% of physeal cross-sectional area is violated
- - oblique tunnel position
- - interference screw fixation
- - high-speed tunnel reaming
- - lateral extra-articular tenodesis
- - dissection close to the perichondral ring of LaCroix
- - suturing near tibial tubercle
51
Postop ACL rehab focuses/avoidances
```
Eccentric strenghtening at 3 wks
Closed chain (foot planted) exercises
```
AVOID: isokinetic quad strengthening, open chain quad strengthening
Lowest ACL strain with isometric hamstring at 60-90 degrees flexion; or quad+ham at that amount
52
Most common cause of failure after ACL
Improper tunnel position
53
Problem with vertical femoral tunnel placement
Rotational instability that can be identified with pivot shift test
54
Problem with too anterior femoral tunnel placement in ACL
Knee is tight in flexion & loose in extension
55
Problem with too posterior femoral tunnel placement in ACL
Knee is lax in flexion & tight in extension
56
Problem with tibial tunnel that is too anterior in ACL recon
Knee is tight in flexion with impingement in extension
57
Problem with tibial tunnel that is too posterior in ACL recon
ACL will impinge with the PCL
58
Treatment septic arthritis in ACL reconstruction
Most common bug is S. epidermidis
Tx: Immediate arthroscopic I&D
Can often retain graft with multiple I&Ds and abx (6 wks minimum)
Better success with graft retention with S. epideridimis than S. aureus
59
Reduced gene expression associated with increased risk of ACL rupture in women
COL5A1
60
Most common nerve injured in autologous ACL reconstruction
Infrapatellar branch of the saphenous nerve --- provides sensation over the anterolateral infra-patellar area of the leg
61
In ACL deficient knee, what gait parameters are lost
- - absence of normal femoral internal rotation during terminal swing phase
- - decreased anterior translation of the tibia in late swing phase
62
Critical angle over which graft-screw divergence increases risk of ACL failure
15-30 degrees --- most commonly seen in the femur
63
Provides the most important restraint to anterior tibial translation in the ACL-deficient knee
Posterior horn of the medial meniscus
64
Mechanism of PCL injury
- - direct blow to proximal tibia with flexed knee (dashboard injury)
- - noncontact hyperflexion with plantar-flexed foot
65
Long term effect of chronic PCL deficiency
-- increased contact pressures in PFJ and medial compartment d/t varus alignment
66
Blood supply to PCL
Middle geniculate artery
67
Treatment of grade I/II PCLs
Nonop: protected WB & rehab --- quad rehab with focus on knee extensor strengthening; return to sports in 2-4 wks
68
Treatment of grade III PCLs
Nonop: extension bracing with limited daily ROM execises; imobilizaiton followed by quad strengthening
69
Indications for surgery for PCL injuries
- - Mulitligamentous knee injury
- - grade II/III injuries with bony avulsion
- - Isolated chronic PCL with functionally unstable knee
70
Treatment of chronic PCL deficiency
Medial opening wedge osteotomy
71
Mechanism of LCL injury
Most frequenly from MVAs or athletic injuries --- direct blow or force on weight bearing knee --- excessive varus stress, tibial ER and/or hyperextension
Rarely isolated injury; usually w other ligs (esp posterolateral corner injury)
72
Order of structures inserting on the proximal fibular head (posterolateral corner)
LCL --> popliteofibular ligament --> biceps femoris
73
Origin and insertion of LCL
Origin: lateral femoral condyle; posterior & proximal to popliteus
Insertion: Anterolateral fibular head; most anterior structure on prox fibula
74
Blood supply to the LCL
Superolateral and inferolateral geniculate arteries
75
Varus stress test findings at 0 and 30
opens at 0 & 30 --- LCL + ACL/PCL
| opens at 0 only --- LCL only
76
Indications for nonop treatment of LCL injury
Isolated grade I or II injury (no instability at 0)
77
Nonop treatment of LCL injuries
Isolated grade I or II injury (no instability at 0)
Limited immobilization, progressive ROM & fnl rehab
Return to sport in 6-8 wks
78
Operative treatment of LCL injuries
Indiations: grade III LCL injury; PLC injury; ACL/PCL injury
Repair vs reconstruction +/- PLC/ACL/PCL recon
Better outcomes with acute repair
79
Primary restraints to rotational motion in the knee
The LCL, popliteus tendon, and popliteofibular ligament
80
Funciton of posterolateral corner
Popliteus works with PCL to control tibial ER, varus, & posterior translatoin of tibia
Popliteus & popfib lig function maximally in knee flexion to resist ER
LCL primary restraint to varus at 5 and 25 degrees knee flexion
81
Dial test
>10 deg ER asymmetry at 30 deg only = isolated PLC injury
| > 10 deg ER asymmetry at 30 & 90 deg = PLC + PCL injury
82
Nonop treatment of posterolateral corner injuries
Indications: grade I PLC; isolated grade 2 injury
HKB x 4wks, functional rehab, quad strengthening, return to sports at 8 wks
83
Operative treatment of PLC injuries
PLC repair = isolated acute grade 2 injuries
PLC recon = grade III midsubstance injuries
84
Larson (fibular based) PLC reconstruction
- - soft tissue graft passed through bone tunnel in fibular head
- - limbs are then crossed to create figure-of-eight and fixed to lateral femur to a single tunnel
85
Valgus HTO in PLC tear
indicated in patients with varus mechanical alignment
| failure to correct bony alignment jeopardizes ACL and PLC reconstruction success
86
Outcomes PLC ligament repair vs reconstruction
Reconstructions have less revision rates and better outcome scores
87
Risk factors for developing patellar tentinitis
- - males > females
- - volleyball most common
- - more common in adolescents & young adults
- - poor quad/hamstring flexibilty
88
Nonop treatment of patellar tendintis
ice, rest, activity modification, followed by PT
NO cortisone injections (tendon rupture)
89
Indication for surgery in patellar tendintis
-- Pain at all times that is not amenable to conservative tx
-- Partial tears
Surgical excision and suture repair
90
Prepatellar bursitis in wrestler
Septic bursitis
91
MPFL origin & insertion
Origin: between medial epicondyle & adductor tubercle
insertion: superomedial border of patella
Primary constraint to lateral patellar instability 0-20 eg
92
Function of patella
Transmits tensile forces generated by patellar tendon
Increases lever arm of the extensor mechanism
93
Patella joint reaction forces (squatting, descending stairs)
Squatting = 7x body weight
Descending stairs = 2-3x body weight
94
Normal Q angle
Males = 13
Females = 18
line drawn from the anterior superior iliac spine --> middle of patella --> tibial tuberosity
95
Miserable malalignment syndrome
3 anatomic characteristics leading to increased Q angle
1. femoral anteversion
2. genu valgum
3. external tibial torsion
96
Risk factors for patellar instability
- - ligamentous laxity
- - previous patellar instability event
- - "miserable malalignment syndrome" --- femoral anteversion, genu valgum, external tibial torsion
- - osseous --> patella alta, trochlear dysplasia, excessive patellar tilt, lateral femoral condyle hypoplasia
97
Evaluation of patellar height - Blumensaat's line
Blumensaat's line should extend to inferior pole of the patella at 30 degrees of knee flexion
98
Evaluation of patellar height - Insall-Salvatti Index
Patellar tendon length / Patellar length
Normal = 0.8-1.2
99
Evaluation of patellar height - Caton Dechamps method
Tibial plateau - inferior patella face / length of patella face
Normal = 0.6-1.3
100
Lateral patellofemoral angle
Normal opens up laterally
Normal > 11
101
TT-TG distance
Distance between tibial tubercle and trochlear groove
> 20 mm is abnormal
102
Indication for nonoperative treatment of patellar instability
- - first time dislocator
| - - habitual dislocator
103
Nonoperative tx patellar instability
-- NSAIDs, activity modification, PT
PT entails:
- - short term immobilization followed by 6 wks controlled motion
- - closed chain short arc quad exercises
- - quad, core, hip strengthening
- - patellar stabilizing sleeve
104
Indication for MPFL reconstruction
Recurrent instability with no significant alalignment
105
Indication for Fulkerson-typeosteotomy
- -may be used in addition to MPFL or in isolation for significant malalignment
- - TT-TG > mm on CT
106
Indication for Fulkerson-type osteotomy in children
DO NOT do tibial tubercle osteotomy in skeletally immature child --- will injure the physis
107
Risk factors for re-dislocation after patellar dislocation:
Age < 20
Nonoperative treatment
-- bony (trochlear dysplasia, high Q-angle, high TT-TG)
-- soft tissue (weak VMO, patella alta, tight lateral structures)
108
Lateral patellar compression syndrome
Improper tracking of the patella in the trochlear groove
| -- Caused by tight lateral retinaculum ---> on PE can't ever the lateral edge of the patella
109
Treatment of lateral patella compression syndrome
Nonop, Nonop, Nonop
| --> emphasize vastus medialis strengthening & closed chain short arc quadriceps exercises
110
Indications for lateral release for lateral patella compression syndrome
- - evidence of lateral tilting
- - pain rfractory to extensive rehab
- - inability to evert the lateral edge of the patella
- - no instability; limited patellar glide
111
Outerbridge classification of chondromalacia
```
I = softening
II = Fissures
III = Crabmeat changes
IV = Exposed subchondral bone
```
112
Nonoperative tx patellofemoral syndrome
rest, rehab, NSAIDs
PT:
- - vastus medialis strengthening
- - core strengthening
- - closed chain quad exercises
- - strengthening the hip external rotators
113
Demographics of quad tendon rupture
> 40 yo man
Most fail at quad tendon inseration on patella
114
Risk factors for quad tendon rupture
- - renal failure
- - diabetes
- - rheumatoid arthritis
- - hyperparathyroidism
- - connective tissue disorders
- - steroid use
- - intraarticular injections (in 20-33%)
115
Ideal fixation for quad tendon repair
Suture anchors --- have been shown to decrease gap formation and increase ultimate loads to failure
116
Demographics of patellar tendon rupture
30s man
117
Position of knee with greatest forces on patellar tendon
knee flexion > 60 degrees
118
Indications for patellar tendon repair
- - complete patellar tendon ruptures
| - - ability to approximate tendon at site of disruption
119
Indicatoins for patellar tendon reconstruction
-- severely disrupted or degenerative patella tendon
120
Most common location of OCD in the knee
Posterolateral aspect of the medial femoral condyle
121
Treatment of femoral condyle OCD < 4cm^2
Microfracture or OATs
122
Treatment of femoral condyle OCD > 4cm^2
Osteochondral allograft transplantatoin OR autologous chrondrocyte implantation
123
Rehab after microfracture for OCD
protected weight bearing and continuous passive motion (CPM) are used while mesenchymal stem cells mature into mainly fibrocartilage
124
Goal of OATs
- - Goal is to replace a cartilage defect in a high weight bearing area with normal autologous cartilage and bone plug(s) from a lower weight bearing area
- - chondrocytes remain viable, bone graft is incorporated into subchondral bone and overlying cartilage layer heals.
125
Rehab after OATs for OCD
NWB x 3 mos bc risk of dislodging graft
126
Limitations of OATS for OCD
- - size constraints and donor site morbidity limit usage of this technique
- - matching the size and radius of curvature of cartilage defect is difficult
- - fixation strength of graft initially decreases with initial healing response
- - weight bearing should be delayed 3 months
127
Limitations of osteochondral allograft transplant for OCD
- - limited availability and high cost of donor tissue
| - - live allograft tissue carries potential risk of infection
128
Limitations of autologous chondrocyte implantation
- - must have full-thickness cartilage margins around the defect
- - open surgery
- - 2-stage procedure
- - prolonged protection necessary to allow for maturation
129
Contraindications for Fulkerson for patellar OCD
- - superior medial patellar arthrosis (scope before you perform the surgery)
- - skeletal immaturity
130
In consideration of donor site for OATs --- where on the trochlea has the lowest contact pressure?
Dital and medial
131
Factors associated with good short term outcomes following microfracture of the knee
- - high fill rate on follow-up MRI
- - low BMI
- - short duratoin of preop symptoms
132
Risk factors for osteonecrosis
- - alcohol
- - decompression sickness ("the bends")
- - Gaucher's
- - sickle cell
- - hypercoagulable state
- - steroids
- - SLE
- - IBD
- - transplant
- - virus (CMV, hepatitis, HIV, rubella)
- - protease inhibitor
- - trauma
133
Treatment of spontaneous osteonecrosis of the knee
Thought to be a subchondral insufficiency fracture --- thus responds well to nonoperative therapy
-- NSAIDs, narcotics, protected weight bearing
134
Prognostic factors in juvenile OCD
age
- - younger age = better prognosis
- - open distal femoral physis is best predictor of successful nonop tx
location
- - lateral femoral condyle & patella have worse prognosis
- - < 2cm in diameter
appearance
- - sclerosis on XR = poorer prognosis
- - synovial fluid behind lesion on MRI = poorer prognosis
135
Physical exam maneuver for OCD of the knee
Wilson's test == pain with internally rotating the tibia during extension of the knee between 90° and 30°, then relieving the pain with tibial external rotation
136
Indication for nonoperative tx of juvenile osteochondritis dissecans
stable lesion in children with open physes
asymptomatic lesions in adults
50-75% heal without fragmentation
137
Indication for operative tx of juvenile OCD
- - impending physeal closure
- - clinical signs of instability
- - expanding lesions on plain XR
- - failed nonop tx
138
Indication for subchondral drilling of OCD
- - stable lesion seen on arthroscopy
| - - performd either transchondral or retrograde
139
Indicaiton for fixation of unstable OCD
-- unstable lesion seen on arthroscopy or MRI > 2cm in size
140
Indication for chondral resurfacing of unstable OCD
-- Large lesions, >2x2cm
141
Indication for operative tx of Osgood Schlatter's:
90% improve with nonop
- - refractory cases (10% of pts)
- - Skeletally mature with persistent sxs --> ossicle excision
142
Sinding-Larsen-Johansson Syndrome
Overuse injury causing anterior knee pain at the inferior pole of patella at the proximal patella tendon attachment --- similar to Osgood-Schlatter's disease which is at the distal attachment of the patella tendon
143
Tissue for ACL recon graft with highest maximum load to failure
Quadruple semitendinosus & gracilis tendons
144
Function of ACL
"Primary: Resists anterolateral displacement of the tibia on the femur
Secondary: Resists varus displacement at 0 degrees of flexion"
145
Function of PCL
"Primary: Resists posterior tibial displacement, especially at 90 degrees of flexion
Secondary: Resists varus displacement at 0 degrees of flexion"
146
Function of LCL
"Primary: Resists varus displacement at 30 degrees of flexion
Secondary: Resists posterolateral rotatory displacement with flexion that is less than approximately 50 degrees"
147
Funciton of PLC
"Primary: Resists posterolateral rotation of the tibia on the femur
Secondary: Resists varus angulation and posterior displacement of the tibia on the femur"
148
Function of MCL
Primary: Resists valgus angulation
149
Layers of the lateral knee
"Layer I: Iliotibial tract, biceps femoris
Common peroneal nerve lies between layer I and II
Layer 2: Patellar retinaculum
Layer 3: Superficial: LCL, fabellofibular ligament, ALL
Lateral geniculate artery runs between deep and superficial layer
Deep: Arcuate ligament, coronary ligament, popliteus tendon, popliteofibular ligament, capsule"
150
Layers of the medial knee
"Layer I: Sartorius and fascia (patellar retinaculum)
gracilis, semitendinosis, and saphenous nerve run between layer 1 and 2
Layer 2: Semimembranosus, superficial MCL, MPFL, posterior oblique ligament
Layer 3: Deep MCL, capsule, coronary ligament"
151
Anteromedial bundle of the ACL function
"fibers are parallel in extension
fibers are externally rotated in flexion
tight in both flexion and extension"
152
Posterolateral bundle of the ACL function
"PL bundle prevents pivot shift
prevents internal tibial rotation with knee near extension
tight in extension, loose in flexion"
153
Blood supply to ACL
middle geniculae artery
154
Tensile strength of native ACL vs BPTB vs quadrupled hamstring:
native ACL 2200 N
BPTB 3000N
quadrupled hamstring 4000N
155
Anterolateral bundle of PCL
Tight in flexion
Mnemonic --- ""PAL"" -- PCL has an AnteroLateral bundle
156
Posteromedial bundler of PCL
Tight in extension
157
Ligament of Humphrey
Meniscofemoral ligament originating from posterior horn of the lateral meniscus and attaches to lateral surface of MFC just ANTERIOR to the PCL
158
Ligament of Wrisberg
Meniscofemoral ligament originating from posterior horn of the lateral meniscus and attaches to lateral surface of MFC just POSTERIOR to the PCL
159
Origin and insertion of superficial MCL
"Origin: pedial femoral epicondyle
Insertion: periosteum of proximal tibial just deep to pes anserinus
Runs just deep to gracilis and semitendinosus"
160
Function of MPFL
Restraint against lateral translation of the patella at 0 to 30 degrees of knee flexion
161
Avulsion fx of ALL insertion
ACL rupture
This is a Segond fx
75% associated with ACL
162
Order of neurovascular structures in the posterior knee running from superficial to deep
Superficial to deep && lateral to medial
Tibial nerve -> popliteal vein ->, popliteal artery
