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