Chapter 15: Knee Conditions
Iliotibial Band Friction Syndrome
- MOI: excessive compression and friction; associated with overuse, abnormal biomechanics and poor flexibility - signs: pain with exercise and ADL, extreme point tenderness at epicondyle joint line, and + Noble and Ober Compression test
epiphyseal and apophyseal fracture
- MOI: forced flexion of knee against a straining quadriceps contraction, violent quadriceps contraction against a fixed foot, ecchymosis, difficulty going up and down stairs
Patellofemoral Stress Syndrome
- MOI: poor patellar tracking caused by weak VMO or tight lateral structures - signs: dull/aching pain, point tenderness -- lateral facet of patella, pain with manual patella compression
Longitudinal Meniscal Tear
- MOI: twisting motion when foot fixed and knee flexed - produces compression and torsion on posterior peripheral attachment
distal femoral epiphyseal fracture
- MOI: varus or valgus stress applied on a fixed, weight-bearing foot - signs: pain around knee, unable to bear weight
Straight Anterior Instability (anterior instability)
- anterior displacement of tibia on femur - involves ACL - MOI: cutting or turning maneuver, landing or sudden deceleration - signs: effusion within 3 hours; reports knee giving way, deep knee pain
Anteromedial instability
- anterior external rotation of medial tibia condyle on femur - involves MCL and oblique popliteal ligament, potentially ACL and medial meniscus - signs: + Slocum drawer test, + Lachman test, increase anterior translation of the medial tibial plateau
Anterolateral instability
- anterior internal subluxation of lateral tibial condyle - MOI: sudden deceleration and cutting maneuver - involves ACL, IT band and lateral capsule - increase anterior translation of the lateral tibial plateau
ACL prevents
- anterior translation of tibia on femur - rotation of tibia on femur - hyperextension
Patella Plica Syndrome
- asymptomatic until trauma - signs: slight joint effusion, pain with prolonged sitting, pain and crepitus (medial and lateral retinacular regions), and + medial synovial plica and stutter tests
Osteochondritis Dissecans
- bone fragment caused by localized area of avascular necrosis - MOI: direct or indirect trauma, skeletal abnormalities, prominent tibial spine or ligamentous laxity - signs: aching, diffuse pain or swelling
avulsion fracture
- caused by direct trauma, excessive tensile forces, overuse - signs: localized pain and tenderness over the bony site
Extensor Tendon Rupture
- caused by powerful eccentric muscle contractions - signs: partial rupture (pain and weakness in knee extension) and total rupture distal to patella (high-riding patella, palpable defect over the tendon, inability to extend knee extension or perform a straight leg raise)
Patellar Tendinitis
- caused by repetitive or eccentric knee extension activities - signs: initial pain after activity (inferior pole of patella or distal attachment of patellar tendon), progression pain at start of activity, pain going up and down stairs
Chondromalacia
- degeneration in articular cartilage of patella - MOI: abnormal excursion and compressive forces - signs: tenderness, anterior knee pain, + Clarke test and + Waldron test
Patellar Instability and Dislocation
- displacement of patella caused by internal or external forces - MOI: deceleration combined with a cutting motion - signs: feeling of patella when cutting, tenderness (medial extensor retinaculum) and + apprehension test
horizontal meniscal tear
- due largely to degeneration - shearing from rotational forces - tears the inner surface fo the meniscus
Iliotibial Band
- extends from tensor fascia latae to Gerdy tubercle on lateral tibial plateau - lateral knee stabilizer
Common stress fracture sites
- femoral supracondylar region - medial tibial plateau - tibia tubercle
Tibial Nerve
- hamstrings except short head of biceps - L4, L5, S1-S3
Sinding-Larsen-Johansson Disease
- inflammation or partial avulsion of apex of patella caused by traction forces - signs: pain with palpation of inferior patellar pole with patient's knee extended and patellar tendon relaxed, and gradual onset of pain
Osgood-Schlatter Disease
- inflammation or partial avulsion of tibial apophysis caused by traction forces - signs: tubercle enlarged, pain @ extreme knee extension and forced flexion, pain during activity
Straight Lateral Instability (varus laxity)
- involves LCL and PCL - medial forces produce tension on lateral aspect of knee - not usually isolated: presence of IT band, biceps femoris, popliteus
straight medial instability (valgus laxity)
- involves MCL; posterior medial capsule, possibly PCL - lateral forces cause tension on medial aspect of knee
Osteochondral fracture
- involves articular cartilage underlying bone - caused by compression from direct blow to knee
Posterolateral Instability
- lateral tibial plateau rotates posteriorly - MOI: hyperextension with varus - signs: soft end point, + posterolateral drawer and external rotation recurvatum tests
Signs of Meniscal Conditions
- limited sensory nerve supply - minimal disability - delayed swelling - joint line pain - clicking, locking, buckling knee - + McMurray, Apley compression, "bounce home" test
A-Angle
- measures relationship of patella to tibial tubercle - 35 degrees or greater linked to increased patellofemoral pain
Patellofemoral Pain Causes
- mechanical (patellar subluxation/dislocation) - inflammatory (prepatellar bursitis, patellar tendinitis)
Posteromedial Instability
- medial tibial plateau shifts posteriorly on the femur and opens medially - involves superficial MCL, ACL, PCL, posteromedial capsule and oblique popliteal ligament - signs: + posteromedial drawer test and posteromedial pivot shift test
First Degree of Valgus Laxity
- mild pain medial joint line - little or no joint effusion/mild swelling - full ROM with minor discomfort
Knee Dislocation/Subluxation
- minimum of 3 ligaments must be torn for knee to dislocate - most common: ACL, PCL, and one collateral ligament - signs: deformity, "pop"
Arcuate
- oblique popliteal ligament and arcuate popliteal ligament - supports posterior joint capsule - limits anterior displacement of tibia on femur - limits hyperextension and hyperflexion
muscular strength, endurance and power
- open chain exercises - PNF-resisted exercises
prevention of knee injuries
- physical conditioning (strength and flexibility) - rule changes - footwear
baker cyst
- posterior aspect of knee, most often: semimembranosus - increase pain with full extension or flexion
Patella Functions
- protect femur - increase effective power of quadriceps
Functions of Meniscus
- shock absorption - provide lubrication/nourishment - stabilize joint - weight distribution
Bursa inside of capsule
- suprapatellar bursa - subpopliteal bursa - semimembranosus bursa
Straight Posterior Instability
- tibia displaced posteriorly - involves PCL - MOI: hyperextension force, fall on flexed knee - signs: rapid joint effusion, decrease knee flexion, + reverse Lachman test
patellar fracture types
- transverse - stellate - comminuted - longitudinal
Second Degree of Valgus Laxity
- unable to fully extend the leg - often walk on the ball of foot
Third Degree of Valgus Laxity
- valgus 0 degrees, with a soft or absent end feel
Patellofemoral Joint Motion
- with knee flexion and extension, patella glides in the trochlear groove - tracking is dependent on the direction of the net force produced by the attached quadriceps
Bursa outside of capsule
-prepatellar bursa -superficial infrapatellar bursa -deep infrapatellar bursa
ways to classify ligamentous knee injury
1. functional disruption of a specific ligament 2. amount of laxity 3. direction of laxity
Hip Flexion Myotome
L1, L2
Knee extension Myotome
L3
Patella Reflexes
L3, L4
Ankle Dorsiflexion Myotome
L4
Toe Extension Myotome
L5
Peroneal Nerve Contusion
MOI: blow to the posterolateral aspect of the knee signs: radiating pain down lateral aspect of leg and foot, weakness in dorsiflexion or eversion, loss of sensation in dorsum of foot
Knee Contusion
MOI: compression signs: localized tenderness, pain, swelling
Infrapatellar Fat Pad Contusion
MOI: entrapped between the femur and tibia signs: locking, catching, palpable pain on either side of patellar tendon, extreme pain on forced extension
infrapatellar bursitis
MOI: friction between patellar tendon and fat pad/tibia signs: point tender with possible swelling posterior to patellar tendon, increased pain at end range of resisted knee extension and passive flexion
Pes Anserine Bursitis
MOI: friction between tendon and MCL, direct trauma signs: pain with knee flexion
prepatellar bursitis
MOI: repetitive direct blow to anterior patella signs: swelling, pain with direct pressure and passive knee flexion
Achilles Tendon Reflexes
S1
Ankle Plantarflexion, Foot Eversion, or Hip Extension Myotome
S1
Knee Flexion Myotome
S2
Q-Angle
angle between line of resultant force produced by quadriceps and line of patellar tendon Males: 12 degrees Females: 22 degrees
tibiofemoral joint flexion
as angle of joint increase to 90 degrees, increase shear force produced by weight bearing
restoration of proprioception and balance
closed chain exercises
Forces at patellofemoral joint
compression during normal walking (50% body weight); increases with stair climbing
Articular Capsule
encompasses both tibiofemoral and patellofemoral joints
Meniscus
fibrocartilaginous disks attached to tibial plateaus
Midstance
flexed 20 degrees, internally rotated 5 degrees and slightly abducted
Swing Phase
flexed 70 degrees, externally rotated 15 degrees and 5 degrees adduction
Increased Q-Angle
increase lateral patellofemoral contact
Decreased Q-Angle
increase medial tibiofemoral contact
Chondral Fracture
involves articular cartilage
when the ACL posterolateral bundle is taut...
knee in full extension
when the PCL posterior fibers are taut...
knee in full extension
when the ACL anteromedial bundle is taut...
knee in full flexion
when the PCL anterior fibers are taut...
knee in full flexion
LCL resists
laterally directed (varus) forces
Hypomobile Patellar Glide
less than one quadrant of displacement
Bucket-Handle Tear
longitudinal segment displaced medially toward center of tibia
MCL resists
medial directed (valgus) forces can also cause a possible injury to medial meniscus
Medial Meniscus vs. Lateral Meniscus
medial is thinner than the lateral meniscus being thicker and more floating
stress management
physician referral and rest
PCL resists
posterior displacement of tibia on femur
Knee Flexion
produced by Hamstrings assisted by Popliteus, Gastrocnemius, Gracilis and Sartorius
Knee Extension
produced by Quadriceps: rectus femoris, vastus lateralis, vastus intermedius, vastus medialis
"Screw-Home" Mechanism
produces a locking of the knee in final degrees during extension close-packed position of full extension
Femoral Nerve
quadriceps, L2-L4
Common Peroneal Nerve
short head of biceps
Fracture management
standard acute, immobilization, immediate physician referral
tibiofemoral joint shearing
tendency for the femur to displace anteriorly
Hypermobile Patellar Glide
three or more quadrants (greater than one-half of patellar width)
Parrot-Beak Tear
two tears; commonly in middle segment of lateral meniscus
tibiofemoral joint extension
weight bearing and tension in muscles increase compression