Knee Flashcards
Which side (medial or lateral) of trochlear groove is higher?
Lateral
> Increases lateral stability of patella
What X-ray shows the relationship between trochlear groove and patella?
Axial oblique view (aka skyline view, Merchant view)
What are the two main measurements taken from the axial oblique Xray of the knee?
Sulcus angle and congruence angle.
Sulcus angle: angle of trochlear groove (Normal = 138)
Congruence angle: reflects patella’s position within groove (normal = -6 deg: Slight medial tilt)
Normal anatomical axis of tibiofemoral joint
185 deg.
> 185 = genu valgum
< 175 = genu varum
Shape of each meniscus
Lateral: O
Medial: C
What percentage of the load on the knee can be managed by the menisci?
70%
Are menisci innervated?
Yes - with pain receptors and joint mechanoreceptors.
Function of LCL
Restrains varus angulation and excessive lateral rotation of tibia
What position should knee be in to preferentially test LCL and MCL?
30 degrees knee flexion
Blood and nerve supply to ACL and PCL
Genicular artery Tibial nerve (mechanoreceptors)
Bundles of the ACL
Anteriormedial: More dominant in flexed positions. Smaller.
Posteriorlateral: More dominant in extended position
Positions that > taught ACL
Internal rotation of tibia, especially near full extension.
Anterior translation of tibia (including pull of quads)
Anteromedial bundle: Taught throughout flexion. Most commonly injured in a partial tear.
Posterolateral bundle: Taught at 0-20 deg
Note: soleus and hamstrings can create posterior pull of tibia to relieve strain of ACL.
Flexion?
Most common noncontact mechanism of ACL injury
Deceleration with knee in slight flexion + tibial rotation (typically internal rotation)
Bundles of PCL
Anterolateral: Tight in flexion. 95% of substance.
Posteromedial: Tight in extesnion
(Restoration of anterolateral bundle is surgical priority)
Most common mechanism of PCL injury
Hyperflexion of the knee
Greatest posterior tibial translation occurs between 70-90 deg
Primary muscular restrain to lateral patellar migration
VMO (fibers oriented 55 deg medially)
How to strengthen VMO
Through whole quadriceps strengthening. Poor evidence that you can strengthen it in isolation.
Concurrent movement of tibia with extension and flexion
Extension: slight valgus + lateral rotation (screw home mechanism)
Flexion: Slight varus + internal rotation
What types of exercise create the least shear forces on ACL?
Weight bearing.
What is the “odd facet”?
Extreme medial edge of the patella - in contact with femur in deep angles of knee flexion.
Position of patella during knee extension
Loosely in trochlear groove, only the inferior pole in contact with the femur.
Position of patella at 90 deg knee flexion
Gliding inferiorly - Superior third is primary contact surface.
Q angle
Describes the structural relationship between quadriceps and patella.
Normal:
Men = 10-15
Women = 15-20
Positions of highest stress on PF joint:
Terminal 30 degrees of extension in NWB
Flexion >90 degrees in WB
(smaller PF contact surface area > increased pressure)
Ottawa Knee Rules
X Ray needed if any of these are positive:
Age > 55
Isolated tenderness of patella
Tenderness of fibular head
Inability to flex knee to 90 deg
Inability to bear weight (4 steps) both immediately and in ED
100% Sn
Pittsburgh Knee Rule
X Ray needed if: Blunt trauma or fall AND either - Age <12 or >50 - Unable to walk 4 steps in the ED
100% Sn, 79% Sp
Signs of SCFE
Reproduction of knee pain with FABER
Loss of hip IR
Excessive hip ER
What to do if SCFE suspected
Refer immediately for hip radiographs
Measuring effusion
1+ Able to milk swelling proximally and it does not return on its own, returns with lateral sweep
2+ Able to milk swelling proximally but it returns without lateral sweep
3+ Unable to milk swelling proximally
Grading varus and valgus stress tests
1+: 3-5 mm
2+: 5-10 mm
3+ > 10 mm
Best ACL test
Lachman best in clinic (better Sn and Sp). Anterior drawer ok for chronic ACL deficiency.
Pivot shift under anesthesia is also good. Not good in clinic.
Tests that indicate posterolateral corner injury
Posterior drawer: increased at 30 deg but normal at 90 deg
Prone external rotation (dial) test: ER > 10 deg more than other side. Positive at 30 and normal at 90 deg
Best tests for meniscus
Joint line tenderness, JLT + McMurray, JLT + Thessaly, or composite score
Meniscus composite score
History of catching/ locking Joint line tenderness Pain with hyperextension Pain with max knee flexion Pain or audible click with McMurray test
^Specific, not sensitive. >90% Sp if 3 positive
Patellofemoral tests
- Seated resisted quadriceps make test throughout ROM
- Movie theater sign
- Step down test
Strongest shift in probability of diagnosis (2 of 3):
- pain with isometric quad contraction
- pain during squatting
- pain during palpation of posteromedial or posterolateral border of patella.
Patellar apprehension test
With knee in 20-30 deg flexion.
+): Apprehension or excessive movement (>50% width of patella
Patellar tilt test
Lateral edge of patella can normally be tilted above horizontal.
Which hop tests are strongest predictors of self-reported knee function?
Crossover and 6 meter timed hop tests
What Y balance score indicates increased injury risk
Anterior limb symmetry difference >4 cm
Sxs indicative of red flags
Rapid gain or loss of weight, fever, night pain unrelated to movement, insidious pain, unexplained joint aching and malaise.
What components are included in a “prognosis?”
Predicted optimal level of patient improvement
Time required to achieve goals
Plan of care (interventions)
Loose-packed position of the knee (Tibiofemoral joint)
25 to 30 deg flexion
Why to keep foot plantar flexed during knee extension stretching
Decreases moment arm of gastroc as a knee flexor
Optimal static stretch parameters
3-4 reps x30 seconds
NMES for quad strength
Train at at least 50% MVIC
Isometric contraction
Use as long as affected quad output is <80% of unaffected side.
Best type of muscle contraction for building strength
Eccentric (but should be used in conjunction with concentric exs)
Ideal hamstring to quadriceps ratios:
Males > 66%
Females > 75%
Has perturbation training been found to promote coordination in muscular activity and teach subjects to dynamically stabilize the knee in response to unexpected disturbances?
Yes
Which type of patellar taping is best for pain relief?
Whichever technique provides the most symptomatic relief.
Knee Soreness Rules
- Soreness during warm up that continues: 2 days off, drop down 1 step
- Soreness during warm up that goes away: Stay at this step
- Soreness during warm up, goes away, comes back during session: 2 days off, drop down 1 step
- Soreness next day: 1 day off, stay at this step
- No soreness: Advance 1 step per week
Unloading braces
Can be effective for pain relief unicompartmental OA, if fit properly.
Minimal relief in obese patients
No evidence that these braces slow or reverse OA
Braces for ligamentous injuries
- No conclusive evidence to demonstrate effectiveness of knee braces on preventing injuries
- Patients believe they help
- Bracing 1-2 years post ACLR > decreased quad muscle strength compared to brace for 3 months.
- No evidence to support routine use of post-op bracing following ACLR
- Suggested for non-op management of grade 2-3 MCL
Typical priorities in post-op rehab
- Avoiding arthrofibrosis/ loss of extension ROM
- Increasing quad strength and functional use
Should you use impairment-based or temporally-based criteria for progressions?
Combination
Criteria to participate in screening for ACL copers:
- Isolated ACL tear
- Painfree full ROM
- No effusion
- Quad MVIC at least 70% uninvolved side
- Tolerated single leg hopping on involved side without pain
Criteria to qualify for conservative ACL treatment
- No more than one episode of giving way since injury
- > 80% on hop tests (single, cross, triple, timed)
- KOS ADL scale > 80%
- Global rating score > 60%
How to qualify as an ACL “coper”
Must resume full participation in high level sporting activities for a full year
Risk of different ACL graft harvest sites:
- Patellar tendon: Anterior knee pain, extensor mechanism dysfunction
- Hamstring: Hamstring strains during rehab
Recommended criteria to meet before having ACL repaired:
Full knee extension
Resolution of acute inflammatory process
Weakest time post-op for ACL graft
12 weeks
* Important to have full recovery of quad function by this time so that dynamic stability can protect the graft.
Does hamstring strength recover without intervention after ACL repair?
Yes, even when hamstring tendon used for graft.
Why is MCL rarely surgically repaired at time of ACL reconstruction?
ACL repair provides stable environment for healing of MCL sprain
Which protocol to follow when ACL and PCL repaired concurrently?
PCL
Stabilization outcomes for PCL reconstruction typically worse than ACL.
ACL revision surgery rehab
Slower.
Partial weightbearing for first 1 weeks.
ACL repairs in the skeletally immature
Either postponed until growth plates have closed, or epiphyseal plate-sparing surgical techniques are used.
Successful programs to decrease ACL risk incorporate:
Strengthening and proximal control. Should include: Multiplanar movements Unilateral and bilateral activities Unanticipated or reaction type movements Emphasize good foot positioning and muscle coordination with cutting/landing
PCL injuries: Athletic vs. MVA
Athletic: More likely to be isolated PCL tear
MVA: More likely to have multi-ligament damage
Priorities in PCL rehab (nonsugical)
Reducing joint effusion Improving ROM Initiating strengthening (quads especially)
Avoid hamstring exercises and knee flexion past 70 degrees in higher degree tears
Prognosis of patients with PCL tears
Majority return to pre-injury activity level. No coorelation between functional outcomes and posterior laxity.
PCL reconstruction typically uses ___ graft
Achilles tendon
PCL post-op rehab
Slow progression of ROM, especially flexion. High risk of graft strain and increased laxity.
Limited resisted flexion for at least 8 weeks, maybe up to 4 months.
Function of posterolateral corner
Provides both static and dynamic stability of the knee to prevent excessive hyperextension, varus angulation, and tibial external rotation.
Injuries are usually concomitant with PCL
Posterolateral corner reconstruction/ rehab
- Achilles tendon graft
- Nonweight bearing in knee immobilizer for 6 weeks
- Avoid putting strain on lateral side of knee - i.e. avoid crossing legs in sitting, sit with toes out, not pivoting away on the fixed surgical LE.
- No isolated hamstring exercises until 4 months.
MCL/LCL rehab
- Avoiding varus/valgus forces on the knee during first 6-8 weeks of healing
- Post-op usually in immobilizer at 30 deg for 2-6 weeks.
4 phases of cartilage maturation
- proliferation
- transitional
- remodeling
- maturation
Meniscus conservative rehab
- Avoid squatting, pivoting, cutting, and running to minimize stress to area as it heals.
Meniscectomy vs. repair
Peripheral third of meniscus usually repaired, inner 2/3rds usually excised.
Meniscus post-op rehab (repair)
- Limited weight bearing for 8 weeks.
- Avoid weightbearing flexion > 45 deg for 4 weeks
- Avoid weighbearing flexion > 90 deg for 8 weeks
- Avoid cutting/pivoting for 4-9 months
Meniscus transplant recommended for what types of patients?
- Prior meniscectomy with pain the same compartment
- Age under 40
- No varus/valgus malalignment
- No advanced arthritic changes
- No knee instability
- No quad atrophy, obesity, arthrofibrosis
Meniscus transplant rehab
- 2 weeks partial weighbearing
- 2 weeks limited flexion ROM (0-90)
- Avoid active knee flexion
- Running after 1 year
Single strongest predictor of functional limitations in patients with knee OA
Quad weakness
Efficacy of exercise program in knee OA
Provide short term relief in pain and improved function
Questionable long-term relief or alteration of progession
Injections, supplements, and wedges for knee OA:
- Injections: Typically most helpful within 2-3 months of injection
- Discontinue use of oral supplements if no improvement within 6 months
- No long term benefit of wedges.
High tibial osteotomy
- Can delay need for TKA up to 10 years
- Up to 25% failure rate
- Surgically induced fracture > bony healing considerations for rehab
- No resistance distal to osteotomy site for 4 weeks
Use of CPA for TKA
No recommended
Value of tibiofemoral joint mobilization techniques after TKA
Unclear
When to avoid posterior tibial glides after TKA
In the case of a PCL–sacrificing surgical technique
Best prevention for knee stiffness following TKA
Maximizing preoperative knee ROM
Rehab for subchondral microfracture vs. chondroplasty/debridement
Microfx: NWB 2-4 weeks, no FWB until 8 weeks. 4-8 months before full return to activity. Can take 6mo - 1 yr for cartilage to fully mature.
Chondroplasty: Limited WB for 3-5 days. Return to activity as soon as 4 weeks.
Osteochondral autograft transplantation
Bone plugs covered with hyaline cartilage harvested from non-weighbearing surfaces on femoral condyle
- Only used for lesions < 2 square cm
Autologous chondrocyte implantation
Harvesting articular cartilage and growing chdonrocytes in a lab.
- Used for lesions 1-10 square cm
Rehab after articular cartilage surgeries (OATS or ACI)
- Closely monitor effusion
- Consider location and size of resurfaced lesion
- Significant quad weakness common
Risk factors for patellofemoral pain
Female Decreased quad flexibility Patellar hypermobility Altered VMO response time Decreased knee extension strength Diminished quad explosive strength
Diagnosis of PFP
- Presence of retropatellar or peripatellar pain
- Reproduction of this pain with squatting, stair climbing, prolonged sitting, or other functional activities loading PFJ in flexed position
- Exclusion of other conditions that may cause anterior knee pain.
TIPPS 6 subgroups of pts with PFP
- Hip abd weakness
- Quad weakness
- Patellar hypomobility (<10 mm)
- Patellar hypermobility (>25 mm)
- Pronated foot posture (> +7 on FPI)
- Lower limb biarticular muscle tightness
Orthoses for patients with PFP
Have been helpful for a subgroup of people. No consensus in who these people are or what orthosis is best.
Strengthening quad for patients with patellar subluxation history
NWB knee extension in greater degrees of flexion to help seat patella in the groove.
Lateral release rehab
- Early initiation of medial patellar glides/ ITB stretching to avoid development of lateral scarring
Tibial stress reaction
- Common after tibial tubercle realignment surgery
- Feels like pop or snap, with pain at tibial tubercle
- Recovers quickly if returned to immobilizer and symptom management for a few days.
Recommended parameters for exercised-based knee injury prevention programs
- Multiple components, including proximal control exercises and combo of strength and plyo
- Balance should not be sole component. Balance training may not be necessary.
- Multiple sessions per week, >20-30 min
- Start in preseason, continue through regular season
- Performed prior to training session/ game
Who should participate in exercise-based knee injury prevention programs?
Female athletes, especially <18 yo (younger girls had greater reduction in ACL injury c program)
Soccer players
Team handball players
All young athletes 12-25 yo (not just those identified as high risk for injury)
Efficacy of exercise-based knee injury prevention programs for basketball and volleyball
Conflicting evidence for basketball
No conclusion can be drawn for volleyball
^All studies in girls
CPG 4 impairment/ function based classification subcategories for PFP
- Overuse/ overload without other impairments
- Muscle performance deficits
- Movement coordination deficits
- Mobility impairments (hyper or hypo)
Impairments associated with PFP
Impaired quad, hip strength
Poor biomechanics - increased frontal plane projection angle with squatting and jump landing.
No correlation between anthropometrics and PFP
Predictors of poor outcomes in patients with PFP
Longer duration of sxs before intervention
Poorer function
Worse pain
Association between PFP and PF OA?
Insufficient evidence
MCL and meniscus vascularization
MCL: Well vascularized throughout life
Meniscus: well vascularized earlier in life, decreases with age
MCL restraint of valgus force
Accounts for 60% of restraint in full extension
Accounts for 78% of restraint at 25 deg of flexion
Which exercise puts the greatest strain on ACL?
Isometric contraction of quads in 15 def flexion
Kellgren and Lawrence grades
grade 0: no radiographic features of OA are present
grade 1: doubtful joint space narrowing (JSN) and possible osteophytic lipping
grade 2: definite osteophytes and possible JSN on anteroposterior weight-bearing radiograph
grade 3: multiple osteophytes, definite JSN, sclerosis, possible bony deformity
grade 4: large osteophytes, marked JSN, severe sclerosis and definite bony deformity
Posterilateral corner of lateral meniscus
Separated from capsule by popliteus tendon> avascular
Posterior oblique and arcuate ligaments
Posterior oblique: Medial
Arcuate: Posterolateral
Ideal hamstring to quad ratio
Men: 66%
Women: 75%
