What is a plica?
Remnants of synovial divisions from development; most common locations are the suprapetellar, mediopatellar plica, lateral synovial plica, infrapatellar plica (the most common plica and least symptomatic of all)
Describe symptoms of an irritated plica?
Most common symptoms location is along the medial (inside) of the knee. Symptoms mimic PFPS and can refer pain to the medial meniscus and cause paients pain "under the kneecap". Pain with prolonged sitting, prompting the term "moviegoer's sign" because it is less painful in ext; may cause pseudo-locking, may cause a pop beneath the patella or snap over the medial femoral condyle.
Describe the patellar trochlear groove contact from full ext to flexion:
0-20 no patellar femoral contact until 30 where the distal third contact the uppermost part of the femoral condyles; @45 the middle third contacts; @ 90 the distal third contacts; end range the odd facets contact
Patella baja may result from adhesions from what bursa?
infrapatellar bursa; most likely to occur after medialization of the tibial tuberosity or patellar tendon graft for an ACL repair
Describe the "lateral blow out" sign of the knee
the ant lateral portion of the capsule is thin and swelling will bulge outward in this area especially in knee flexion; may indicate lateral meniscus tear
Discuss the role of the posterior oblique ligament:
predominant ligamentous structure on the post-med corner of the knee; prevents posterior translational
What important does the arcuate complex provide:
each step at heel stroke with the near full ext exerts tremendous force across the posterior lateral knee (posterior one third of lateral supporting structures: LCL, arcuate lig an ext of the popliteus) helps control IR of the femur on a fixed tibia or ER during open chain
Function of the ACL
prevents recurvatum prevents IR of the tibia in open chain and and ER in closed chain, stops ant translation of the femur on the on the fixed tibia
Function of the PCL
stop posterior translation of the tibia of the tibia on the femur; decelerator of the femur
Function of the IT Band
aids in ext, but when the knee is bent past 30 degrees it slides back and becomes a flexor; also contribute to prevent pivot shift to aid the ACL
Anatomic reasons for patellar instability?
High Q-angle (norm for males 13 females 18), loose retinaculum, patella alta, weak or dysplastic vastus medialis obliquus muscle, flattened lateral femoral condyle
Do cruiciate ligaments really cross?
yes, the twist upon themselves during knee flexion and extension
What is the normal measurement of tibial torsion?
12-18 degress of lateral tibial torsion, so the lateral malleloi will be more posterior than the medial
Which meniscus is most commonly injured and why?
medial meniscus, it is adhered to the medial collateral ligament; there is also increased WB'ing on the medial portion of the knee
What is the function of popliteus?
unlocking and IR rotating the knee during flexion, aids with stabilization for balance, protects the latearl mensicus, prevents ant translation of the femur
What is the q-angle?
Angle from the ASIS to the center of the patella to the tibial tuberosity
What may increase a Q angle?
femoral anteversion, external tibial torsion, genu valgum, pes planus
What anatomic structures encourage lateral tracking of the patella
dysplastic patella, patella alta, shallow intercondylar groove, tight rentiaculum, tight IT band
Function of VMO
prevents subluxation of the patella, counter acts vastus laterallis; acting alone it is unable to ext the knee works harmoniously with the rest of the quad
What is lateral pressure syndrome?
A tight lateral retinaculum pulls and tilts the patella laterally, increases lateral facet
Define bipartite patella?
The patella will still have an intact ossification center, and may be mistaken as a fracture
What is the difference between Osgood-Schlatter disease and sinding larsen-johansson disease
Osgood is an apophysitis of the tibial tubercle and sinding larsen-johanssen disease is apophysitis of the inferior patellar pole
Since articular cartilage is anueral what tissues around the PF joint cause pain?
Define Hoffa's disease
Fat pad syndrome manifests as pain and swelling of the infrapatellar fat pad, usually from direct trauma to the anterior knee, particularly during activities
Treatment approach for instability?
avoid terminal knee ext, suggest ex from 90-30 degrees, use braces and tape
Tx for knee muscle and tendon injuries?
open and closed chain ex with emphasis on eccentrics, stretching
Tx for friction knee injuries
avoid repeated flexion and extension exercises, exercise in pain free ROM; exercise above and below painful ROM
Tx for knee articular injuries
increase quad function, pain free ROM in unloaded environment
Tests for plica syndrome
Stutter and Hughston's plica tests
Prepatellar bursitis either from blunt trauma over repetitive microtrauma over the anterior knee
What is the typical MOI for patellar dislocation?
ER of the tibia with valgus stress to the knee (often occurs because of IR of the femur) often related to strong quad activation; also occurs from blunt trauma
What population are more susceptible to patellar dislocation?
women, adolescent and is often recurrent
Repeat dislocation rate?
20-43% for those being treated with immobilization
Can hip weakness contribute to PF pain?
yes, it is if the track under the train is moving out of place if the external rotators are weak and the femur IR's
How is patellar instability assessed?
1.) static approach: glide the patella laterally >50% of the total patellar width over the edge of the lateral femoral condyle is considered unstable 2.) Dynamic:observe tracking from 30 flexion to full ext and if the patella makes an abrupt lateral movement like a J it is unstable
Why should strengthening be avoided above 40 degrees if there is lateral tracking or patellar instability?
Because the patella is not well seated in the groove
What's a good way to stretch the inferior fibers of the IT band?
hip add with medial glides of the patella
What muscles are notorious for causing PF pain?
hamstrings, gastroc-soleus, and IT Band
How is a patellar tendon strap supposed to alleviate PF pain?
by displacing the patella upward and slightly anteriorly it theoretically may slightly diminish PF joint reaction force
What structures attach to the medial meniscus:
MCL, joint capsule, coronary ligament of the patella, meniscopatellar fibers, semimembranous tendon
Describe the vascular areas of the meniscus:
the outermost areas have the most blood flow “red-red zone” and as it moves to the middle of the knee vascularity decreases red-white to the white-white zones; also the posterior lateral corner is avascular
How important are the menisci in transmitting loads across the knee joint?
they translate 50-60% of the compressive load across the knee; at 90 degrees knee flexion this increses to 85%
Do the menisci move with knee joint motion?
yes, the lateral is more mobile because it is not anchored to like the medial is to the MCL
Most common MOI for meniscus?
twisting or turning manuver while WB'ing and are associated with a ligamentous injury
Signs and symptoms of a meniscus tear?
catching and locking with knee joint pain at rest, tenderness at the joint line, swelling may be present, complaints of giving away, pain with end range flexion and ext; a locked knee typically that won't fully ext indicates a large bucket-handle tear
When is surgery indicated for meniscal tear?
joint line catching and pain, effucsion, locking, and/or giving way that interferes with daily function; failure to respond to conservative measures
What is the usual time for return to function after partial menisectomy?
2-6 wks, rehab progresses rapidly
Describe rehab after meniscal repair?
WBAT in a full ext brace 4-6 wks, full activity in 3-6 months, full range in about 3 wks
What is the shape of the lateral and medial meniscus
medial is C shape, lateral is O shaped
what ligaments of knee can be disrupted by a hyperextension force?
Which ligament of the knee may be disrupted by a MVA in which the tibial tuberosity strikes the dashboard?
What ligament may be injured by a crossover cut maneuver
Which structure of the knee can be injured during a side step manuver with valgus force?
from valgus: MCL or tibial collateral with possible medial meniscus; lateral side: lateral meniscus may be impinged with possible ACL if forces are strong enough
How could an occult osteochondral lesion be associated with ACL rupture and where is it commonly found?
bone bruise commonly found at the lateral femoral condyle and the posterolateral tibial plateau
How might an occult osteochonrdal lesion with ACL rupture affect long term outcomes?
May turn into an osteochondral defect and make degenerative changes occur
What is a Segond fracture?
avulsion Fx of the anterolateral margin of the lateral tibial plateau with ACL injry
What is better for ACL reconstruction: allograft or autograft?
Why are females at higher risk for ACL rupture:
Less muscle mass per total body weight, greater joint hyperext, greater joint rotational laxity, increased femoral IR (causing valgus injury), increased Q angle, increase foot pronation, small diameter ACL, smaller skeletal size; possible hormonal relation with menstral cycle; over utilization of quad, tendency of females to land and jump and perform cuts from an upright position
What is the effectiveness if any of ACL prevention programs for female athletes?
scarce lit but up to 88% at 1 year 74% at two years
Define anteromedial instability. Which clinical tests are positive
slightly flexed knee forced into valgu while the tibia ER, usually damages the MCL and ACL; positive lachman's, ant drawer, valgus test at 20-30 degrees
Define anterolateral instability, which clinical tests are positive?
classic MOI is noncontact decelerationon a planted foot, slightly flexed knee is forced into varus while the tibia IR's; ACL, LCL, ITB are usually injured; pivot-shift test is positive
Define straight medial knee instability?
valgus blow in ext: PCL, MCL, middle 1/3 of capsular ligaments possible medial and lateral menisci; positive valgus test in ext
define posterolateral rotary instability
varus blow from the anterior direction on a slightly flexed knee with the foot planted; Arcuate complex (LCL, posterior oblique ligament, popliteus tendon; positive reverse pivot shift , posterior lateral drawer sign, ER recurvatum, Loomer's PLRI test
Define straight lateral knee ligament instability?
varus blow in ext: PCL, LCL, ITB, tract fibers, middle 1/3 of capsular ligaments,possibly the menisci; diffculty with heel strike; possible posterior sag
What is the best test for ACL?
Lachman's; pivot shift has high false positive rate
During open chain ex when does max stress fall on the ACL?
At 20 degrees during ext ex starting from 45; very little stress placed at full ext
Do open chain and closed ex put about the same amount of stress on the ACL?
What are common guidelines for activities after ACL reconstruction?
50% quad strength for jogging, 65% quad for sports agility; 80% quad strength for full return to sports
grading for collateral ligament injuries?
grade I: 10mm joint line opening
Difference between ACL and MCL injuries?
ACL more likley to progress and won't heal, most MCL injuries up to a 2+ will heal
Most common grafts for ACL
BPTB and hamstring
Most common graft for PCL
Desribe tx for MCL injury
grade I and II immobilization for 48 hours, gentle ROM and progression of ex as tolerated; grade 3 injuries treated similarly but surgery may be indicated
In a young prepubescent individual with a positive valgus test what is the most likley injury?
Epiphyseal plate injury not MCL; the MCL is stronger the epiphyseal plate
What age does a quad tendon rupture typically occur?
>40 y/o MOI forced knee flexion with max quad contraction
Tx quad tendon rupture:
at least 6 wks full ext immobilization and 6 months rehab definite loss of strength
What age does a patellar tendon rupture typically occur?
<40 y/o Hx of patellar tendonitis or steroid injections and high energy trauma
Patellar tendon rupture
6-8 wks with ing
Typical tx for first time patellar dislocation?
6 wks of brace immobilization in full ext
Sugical indication for patellar dislocation?
first time with significant osteochondral fracture, first time with unstable reduction, recurrent not responding the rehab, disruption of the medial patellofemoral ligament on MRI
Indications for lateral retinacular release?
intracable PF pain with lateral tilt, lateral compression syndrome, persistent subluxation, patellar dislocations
Progression of lateral retinacular release?
sport specific and functional activites by 6 wks
What degree of lateral tilt is associated with knee subluxation?
16 degrees, 6 degree medial tilt is considered normal
Does the knee normal have a slight varus or valgus?
Can VMO be preferentially strengthened?
Not according to the most recent evidence
With knee flexion beyond 90 degrees, what happens to the quadriceps tendon?
It contacts the femoral proove providing greater area to dissipate forces
For patellofemoral joint stress what range of NWB exercise should be avoided?
Knee rules for x-rays?
>55 y/o, isloated tenderness of the patella (no other bony tenderness), tenderness of the fibular head,inability to flex the knee to 90 degrees, inability to bear weight both immediately and in the emergency room (4 steps, limiping is okay)
Knee pain in an overweight or very tall thin prepubscent male 8-17 y/o with anterior thigh and/or knee pain and negative knee exam could be what Dx?
Slipped capital femoral epiphysis (SCFE); A FABER that reproduces knee pain and loss of IR at the hip with excessive ER may also be present
What is Legg-Calve Perthes syndrome?
pediatric condition for ages 5-12 y/o avascular necrosis of the femoral head that can present with knee pain
Is knee pain often with Lyme disease?
yes, it is present 90% of cases secondary to swelling or migratory poly arthritis
Describe the posterior sag test:
supine hip at 45 degrees, knee flexion at 90 degrees look for sag that should be able to reduce with quad activation
Describe the posterior drawer test
90 knee knee flexion and posterior force applied can, also be done with ER to the tibia
Test cluster for the posterior lateral corner?
Posterolateral drawer test, prone ER, reverse pivot shift, and ER recurvatum
Posterolateral drawer test:
increased posterior drawer at 30 degrees knee flexion vs 90 degrees
Prone external rotation test:
prone with knees flexed and ER to the B tibia performed at 30 and 90 degrees flexion; increased ER at both angles is positive
Reverse pivot shift test
supine and knee flexion 70-80 degrees; ER the foot and place axial load through the leg, the knee is then extended while a valgus force is placed on the knee
cluster of 5 measurements for meniscus:
hx of catching or locking, joint line tenderness, pain with forced hyperext, pain with maximal knee flexion passive, and pain or click with McMurray's (all 5 positive high specifcity, 3 or more likely ACL involvement)
5 and 20 standing knee flexion with IR and ER twists
PFPS resisted quadriceps test:
resisted but not overpowered knee ext resistance will reproduce ant knee pain throughout the range
“Movie theater sign”
pain with 2 hours of sitting in the anterior knee
Step down test:
anterior knee pain reproduced with measurable angle and VAS
What is a Sage sign:
excessive patellar movement
20-30 degrees knee flexion patella is manually subluxed
Patellar tilt test:
Knee 20 flexion, attempt to flip up the lateral edge of the patella upward
Early on what is the most appropraite exercises s/p Fulkerson osteotmy?
SLR, quad sets, and patellar mobility; too much flexion and WB'ing exercises could cause the osteotmy site to fail
At 4 wks s/p osteotomy Fulkerson what can be initiated at wk 4 and then a wk 7
at wk 4 closed chain exericses minisquats; at wk 7 quad ex >30-40; full lunges and squats should be avoided throughout therapy
What is ligamentous injury would exclude someone from a unicompartmental knee arthroplasty?
What BMI excludes someone from a UKA