Knee Flashcards
Tibiofemoral joint
- tibia and femur
- medial condyle has larger contact w/ tibia than patella
- trochlear groove is higher lateral than medial
Site of impingement for ACL
-intercondylar fossa
Sulcus angle
- measured via radiograph
- lines from the highest peaks of medial and lateral femoral condyle to the deepest part of the trochlear groove
- angles of 138* +/- 6* are normal
- more shallow groove = susceptible to dislocation
Congruency angle
- measured via radiograph
- reflects patella’s position in trochlear groove and midpoint of sulcus angle compared to lowest portion of patellar ridge
- if patellar ridge line falls medial to midpoint of sulcus angle, then value is negative and if lateral then value is positive
- medial tilt of patella 6* is normal and lateral tile of 16* may be associated with subluxation
Tibia: medial vs. lateral
- medial condyle is longer (A to P) than lateral
- osseus structure is less stable due to lack of bony congruency - role of menisci is really important to tibiofemoral jt
Genu valgum vs. varum
- medial angle >185* = valgum –> lateral joint line is compressed and medial is distracted
- angle <175* = varum –> medial compression and lateral distraction
Mechanical axis in single leg vs. double leg stance
-during single leg = axis is shifted medial due to shift in hip position
Menisci
- wedge-shaped fibrocartilaginous disks
- on tibial plateau (cover approx. 2/3 of it)
- disperse WB forces
- thick centers and thin edges
Lateral meniscus
-more O shaped
Medial meniscus
-more C-shaped
Vascular supply to mensici
- comes from periphery
- perihperal 1/3 receives blood supply from capsular arteries (red zone)
- other 2/3 have poor blood supply (red-white, white zone)
What holds the menisci in place?
- coronary ligaments
- other ligaments
- lateral meniscus is connected anteriorly to medial meniscus by transverse ligament and to patella by patellomeniscal ligament (thickening of anterior capsule), posteriorly to popliteus and PCL and to medial femoral condyle via meniscovemoral ligament
- medial meniscus attached to transverse and patellomeniscal ligaments, posteriorly to semimembranosus
Which meniscus is more mobile?
-lateral
Roles of meniscus
1) increased contact area
2) assist with joint gliding
3) limit hyperextension
4) provide cushion
5) support WB surfaces for tibiofemoral joint
Menisci innervation
- pain receptors
- joint mechanoreceptors
Lateral knee compartment
- 3 regions:
1) anterior - lateral retinaculum, ITB, arcuate complex
2) middle
3) posterior
Lateral retinaculum components
- superficial oblique layer extends from ITB to lateral patella
- transverse retinaculum extends from ITB to lateral patellar border
Arcuate complex
- lateral collateral ligament
- arcuate ligament
- popliteus tendon
LCL
- extracapsular
- lateral epicondyle to biceps femoris on femoral head
- restrains excessive lateral rotation of tibia
Medial compartment
- posterior 1/3 reinforced by posterior oblique ligament and semimembranosus
- oblique popliteal ligament reinforces posteromedial aspect
- anterior third consists of deep capsule and medial retinaculum
- middle third is MCL
Posterior oblique ligament
- thickening of medial capsular ligament from adductor tubercle of femur to tibia and posterior capsule
- provides resistance to valgus forces near full extension
MCL
- superficial portion is middle layer of medial compartment - originates in posterior medial femoral condyle and attaches below pes anserine on tibia
- superficial MCL restrains valgus stress
- MCL is on slack in a flexed position
- deep portions of MCL are separated from superficial by bursa
- meniscofemoral and meniscotibial ligaments
- role of deep layer is meniscal support and ctonrol
Knee joint capsule
- formed by tendons
- large lax capsule allows for freedom of motion
- anteromedial and anterior lateral capsules are thick
- posterior capsule is thin
Cruciate ligaments
- intracapsular
- blood supply from genicular artery
- innervated by branches of tibial nerve
- 3 different mechanoreceptors (ruffini, pacinian, golgi tendon)
ACL
- originates at lateral femoral condyle and attaches to intercondylar eminence
- 2 distinct bundles: anterior medial (smaller) and posterolateral
Posterolateral bundle of ACL
-taut in extension and provides greatest restraint to anterior translation in that position until 20* flexion
Anterior medial bundle - ACL
- tight throughout flexion and is tested when anterior translation tests are performed in flexed position
- anterior drawer will be positive even if posterolateral bundle is intact
- increases in tension from 20-90* flexion
Other motions that cause ACL to be taut
- internal rotation of tibia (specifically anterior medial bundle)
- provides stabilizing force against knee hyperextension and secondary support against varus or valgus motions
Non-contact injury to ACL
- often a deceleration injury that occurs in a position of slight flexionc oupled w/ medial or lateral tibial rotation
- in medial rotation ACL winds around PCL
- in lateral rotation ACL stretches over lateral condyle
Oblique popliteal ligament function
-reinforces posteromedial capsule obliquely on a lateral to medial diagonal from proximal to distal
Posterior oblique ligament function
-reinforces posteromedial capsule on a medial to lateral diagnoal from proximal to distal
Arcuate ligament lateral branch function
-reinforces posterolateral capsule on amedial to lateral diagonal from proximal to distal
PCL
- from femoral condyle to posterior tibial tubercle
- anterolateral bundle (larger - 95% of sustance) and posteromedial bundle (5% of substance)
Anterolateral bundle - PCL
- tight in flexion
- restoration of this bundle is surgical priority
- bears 50-75% of posterior force between 40-120*
Posteromedial bundle - PCL
- taut in extension
- bears 57% of posterior force beyond 120*
PCL restrains…
-posterior displacement of tibia on teh femur - 95% of stability between 30* and 90* flexion
When does the greatest posterior tibial translation occur?
-between 70-90* knee flexion since secondary restraints (posterolateral capsule, popliteus, MCL) are too lax to contribute at these angles
PCL - MOI
- most common for isolated injury is hyperflexion of knee
- direct tibial posterior translation such as dashboard injury results in injuries to secondary restraints
- ER of tibia in an isolated posterior lateral corner tear is increased at 30* of knee flexion
VMO fiber orientation
- oriented 55* medially
- has been called the primary restraint to lateral migration of the patella
VMO evidence
-evidence suggests that the VMO cannot be selectively recruited to preferentially strengthen
Knee flexion/extension and varus/valgus
- slight amount of valgus associated w/ ext
- slight amount of varus associated w/ flexion
Screw home mechanism
- lateral rotation of tibia at terminal knee extension
- medial rotation of tibia must occur to allow knee to unlock and initiate flexion
Patella
- largest sesamoid
- medial, lateral facet
- odd facet -medial edge of patella which contacts the femur in deep angles of knee flexion
- only the inferior pole is in contact with femur during full knee extension
Patellar plicae
- folds
- often asymptomatic, but can cause irritation and inflammation resulting in plica syndrome
ligamentum muscosum
- inferior plicae
- attaches from intercondylar fossa to inferior patellar pole
Patellofemoral joint capsule
-exposed to high stress
Instability of patella
- occurs when trochlear groove is shallow
- lateral femoral condyle is less prominent (trochlear dysplasia)
- patellofemoral soft tissue tethers are lax
- bony stability is reduced in terminal extension
Q angle
- line from ASIS to patellar midpoint and a line from midpoint of patella to tibial tuberosity
- women: 15-20*
- men: 10-15*
- angle > 20* are structural abnormalities
MCL testing
- initial test: valgus stress full extension
- most specific test: valgus stress at 30* flexion > 10mm
LCL testing
- initial test: varus stress full extension
- most specific test; varus stress at 30* flexion
PCL testing
- initial test: posterior drawer
- most specific test: posterior sag and quad activation tests
ACL testing
- initial test: lachman test
- most specific test: lachman test w/ empty endfeel
Posterolateral corner testing
- initial test: posterior drawer increased at 30* and normal at 90*
- most specific test: prone ER test > 10* compared to non-involved side
Meniscus testing
- initial test: McMurray, apley, joint line tenderness, thessaly
- most specific test: hx: catching/locking, joint line tenderness, pain with forced hyperext, pain with maximal knee passive flexion, pain or audible click w/ mcmurray
- if 5/5 present on history questions = 92.3% + meniscal tear, 75% if 3/5
Patellofemoral testing
- initial: quadriceps make test, step down test, patellar tilt test
- most specific test: pain during resisted iso quad contraction, squatting, palpation
Grading ligament testing
\+1 = 3 to 5 mm \+2 = 5 to 10 mm \+3 = > 10 mm
Acute ACL reupture and anterior drawer
sensitivy and specificty are poor
Lachman test
Sens 85%
Spec 94%
GOLD STANDARD
Arthrometer
- instrumented devices to assess joint laxity
- commonly used to diagnose ACL injury
- 3 mm difference is used as a threshold for a positive test for ACL rupture - 96% sen, 92% spec
Posterior drawer sens/spec
Sens 90%
Spec 99%
Posterior sag sens/spec
Sens 97.6%
Spec 100%
Prone ER test (dial test)
- pateint prone, clinician grasps distal leg, flex knee, ER tibia
- ER > 10* of uninvolved side = +
- increased ER at 30, but not at 90 indicates isolated posterolateral corner injury
Apley test
- patient prone
- knee flexed to 90*
- patient’s thigh stabilized
- direction of force applied with IR and ER rotation, then repeated with compression
- Sens 68-83%
- Spec 76-97%
Meniscal pathology composite score
1) hx of catching/locking
2) joint line tenderness
3) pain with forced hyperext
4) pain with max knee flexion PROM
5) pain or audible click w/ mcmurray test
all 5 = 92.3% + predictive value
3/5 = 75%
Functional knee tests
1) timed stair climbing
2) six min walk test
3) TUG
4 ) 5 time sit to stand test
ACL - non-surgical care
-
Screening tool for non-surgical ACL rehab to return to short-term high levels of activity
- must have isolated tear, full pain free ROM, no effusion
- -must be able to tolerate single leg hopping on involved knee equal to 70% of non-involved
1) single, cross over, triple, and timed hop tests
2) report o fnumber of giving way episodes from time of injury to testing
3) kos ADLs scale and sports activity scale
4) global ratin gof knee function
Criteria for passing ACL non-surgical screening tool
1) no more than 1 episode of giving way
2) score on hop test of > 80%
3) KOS ADLs scale score of >80%
4) global rating score > 60%
Non-op vs. op return to sport
-both had 68% return to sport rate, but non-op group was more likely to participat ein level2 sports and avoid level 1
ACL surgery
research shows that majority of ACL tears require surgery to return to long term high level sports
Graft options for ACL surgery
1) bone patella tendon bone
2) quadrupled hamstring (semitendinosus, gracilis) tendons
3) various allograft materials
What dictates graft choice?
-orthopedic surgeon’s expertise with a particular procedure
Bone -patella tendon - bone graft
- increased incidence of anterior knee pain and extensor mechanism dysfunction has been reported
- in early rehab phase may be greater risk of patellar fracture
Hamstring tendon grafts
- may result in non postop hamstring strength deficits, but increased risk of hamstring strains during rehab
- harvest site may adhere to surrounding tissue if full extension is not easily achieved and maintained
- patient c/o is usually self limiting
Allograft
- eliminates harvest site problems
- in rare instances, incorporation is not established and graft implant is more like synthetic
Notchplasty
- surgical technique where bone is resected from intercondylar notch
- allows increased space for joint
Timing of ACL reconstruction
- some research suggests it could be linked to potential problems
- acute reconstruction (w/i 3 weeks) is a risk factor for developing stiffness
Primary concern with rehab following ACL reconstruction
- not stressing teh graft
- passive ROM from 0-120* = no strain on graft
- greatest strain is in last 30* of NWB extension
- absence of stress is not the goal = ideal amount of stress for healing is still unknown though
ACL graft is weakest when?
12 weeks post op
Biggest factors that decrease post op function
- weak quad
- loss of full knee ext
Strengthening focus in post op ACL
-quads not hamstrings, but hamstring strength returns on its own
NMES + strengthening
more effective than exercise alone for quad strength and normalizing gait pattern
Double bundle ACL reconstruction
- gaining popularity
- goal is to more accurately reproduce biomechanical properties
- more technically demanding and time consuming
- provides better knee stability based on arthrometer and pivot shift testing
- fails to provide better clinical outcomes
ACL reconstruction + chondral damage rehab
-restriction of WB for first 3-4 weeks
MCL + ACL injury
-ACL reconstruction provides stable environment for healing of even grade III MCL sprain so MCL is rarely surgically repaired at same time
ACL + PCL reconstruction
-PCL rehab guidelines are followed
ACL revision rehab
-Wb and exercises must be slowed down to protect area already compromised
-encouraging full extensionw / gait is important
-
Women vs. men and ACL tears
- females 4 to 8x more likely
- usually non-contact; pivoting and cutting sports
- due to less absorptive landing patterns, muscle weakness, excessive quad activation in eccentric activity
- joint laxity
- hormonal influences
programs to prevent ACL tear
1) incorporate multiplanar components
2) unilateral and bilateral activities due to increase incident of ACL injuries in sls
3) incorporate unanticipated or reaction type movements
4) emphasize correct foot position during cutting
5) consider implications of playing surface, fatigue, bracing
PCL injuries and non-surgical care
-PCL injuries more likely to be grade I or II tears and be treated non-operatively
Grade I and II PCL tears
- rapid recovery
- return to sport w/i 2-4 weeks
- acute management includes reducing effusion, improving ROM, strengthening
- restoration of quad strength = critical to recovery
Grade III PCL tears
- recover more slowly
- may be immobilized in extension for 2-4 weeks (to reduce posterior sublux caused by HS)
- quad exercises are essential
- knee flexion past 70* and isolated HS exercises should be avoided
- return to sports at 3 months
Surgery and PCL tears
- usually use achilles tendon allograft
- replicate anterolateral bundel fo PCL
- reconstruction decreases laxity by 1 grade
Focus of PCL rehab guidelines
- slow progression of ROM - especially flexion
- graft is tensioned between 70-90* flexion
- maintenance of quad strength
MCL and LCL injuries
- usually managed conservatively
- research shows no benefit to surgical management over non-op for MCl
- non-op treatment has mixed results for LCL
- avoid valgus and varus forces and excessive rotation for first 6-8 weeks
MCL and LCL surgical care - post - op rehab
- protection of repair site
- immobilizer or support brace likely used to prevent frontal plane stress
- knee is braced in 30* flexiond uring WB for 2-6 weeks
Meniscal injuries
- can be treated conservatively, with partial or full removal, debridement, repair or allograft
- rehab progression is based on phases of cartilage maturation
- no long term data to support any of the meniscal repair rehab protocols
Meniscal surgery
-tears that are in the peripheral 1/3 are mor elikely to heal and will often be repaired
Rehab following meniscal surgery
-no precautions follow menisectomy
Meniscal repair
- early postop signs that should be monitored are effusion, pain, gait, knee flex and ext ROM, patellar mobmility, strength
- WB should be limited and progressed slowly over 8 weeks
- in the 1st 4 weeks - WB in angles >45* are avoided
Indications for meniscal transplant
- prior menisectomy and pain in the tibiofemoral compartment
- those under age 40
- minimal oa
- not candidates for TKA
contraindications to meniscal transplant
- varus or valgus malalignments
- advanced arthritic changes
- concurrent uncontrolled knee instability
- knee arthrofibrosis
- significant muscle atrophy
- bmi > 30
Post op rehab or meniscal transplant
- PWB for 4 weeks
- WB limited (locked in full ext) for 3-6 weeks
- progress to FWB at 6-9 weeks
- quad isometrics, SlR, active assisted knee extension from 90-0 = immediately
- ckc wb exercises at 3-4 weeks
- ock resistive exercises at 5-6 weeks
- running at 1 year out
Pre-op quad strength and TKA
-research sugggests that it is predictive of functional ability at 1 year out
Rehab following chondroplasty or debridement for cartilage injury
- early passive ROM
- WB is only limited for 3-5 days
- return to full functional activities and initiate impact activities at 4 weeks
Microfracture rehab
- WB limited for 2-4 weeks and no FWB until 8 weeks
- 4-6 months and up to 8 months to resume high impact activities
OATS
- osteochondral autograft transplantation
- bone plugs overed with hyaline cartilage harvested from NWB surface of femoral condyle
- only used if lesion is <2cm squared
ACI
- autologous chondrocyte implantation
- 2 step surgical procedure
- harvest cartilage from patient’s knee - grow chondrocytes in a lb - implant a patch
Risk factors for patellofemoral pain
- female sex
- decreased quad flexibility
- hypermobile patella
- altered VMO response
- decreased knee ext strength
- diminished quad explosive strength
Diagnosing PFP
- lack of gold standard or accepted reference
- use combo of symptoms, local/proximal/distal factors including strength, flexibility, patella alignment, hip and trunk strength and flexibility, ankle and foot strength
Surgical management for patellorfemoral dysfunction
- synovectomy
- lateral retinacular release
- realignment procedures
Osgood-Schlatter disease (osd)
- traction apophysitis of patellar tendon insertion on tib. tub
- 10-15 yr olds
- 25% of the time is (B)
- conservative treatment is usually effective - rest, ice, stretching
Sinding-Larson-Johansson (SLJ) syndrome
- traction apophysitis, but with symptoms at inferior/pole of patella
- 10-12 yr olds
- similar to treatment for OSD
