Chapter 6

The Knee continued

Pathologies and Related Special Tests

Trauma may result from:– Contact-related mechanism– Rotational forces– Overuse– Degenerative changes

Uniplanar knee sprains

Instability in only one plane Isolated to a single structure MCL/LCL = valgus/varus instability in frontal

plane ACL/PCL = anterior/posterior shift in sagittal

plane

Medial Collateral Ligament Sprains

Damaged from:– valgus tensile forces; blow to lateral aspect– Noncontact valgus loading– Rotational force

Force dissipated through:– Full extension – superficial and deep layers of

MCL, anteromedial and posteromedial joint capsule, tendons of pes anserine

– Flexed beyond 20o – superficial layer of MCL

MCL Sprains

Involvement of other structures– Medial joint capsule and medial meniscus– ACL– Distal femoral physis– Patella

Evaluative Findings– Table 6-4, page 218

MCL Sprains

Nonoperative Treatment– Adequate blood supply– Functional rehabilitation

Protection, controlled ROM, strengthening, proprioception training

– Knee braces

Operative Treatment– High complication rate

Lateral Collateral Ligament Sprains

Damaged from:– Blow to medial aspect of knee– Internal rotation of tibia on femur

“springy” end-feel Involvement of other structures

– Lateral capsule– ACL– Peroneal nerve

LCL Sprains

Poor healing properties and its’ importance in providing rotational stability to the knee often necessitates surgical repair

Evaluative Findings– Table 6-5, page 219

Anterior Cruciate Ligament Sprains

Damaged from:– Force causing anterior displacement of tibia on

femur (or femur driven posteriorly)– Noncontact-related rotational forces– Hyperextension of knee– Unlike other ligaments, most arise from

noncontact torsional forces

ACL Sprains

Isolated trauma unlikely Involvement of other structures:

– Other ligaments– Menisci– Anteromedial or anterolateral joint capsule– Per anserine, biceps femoris, IT band

ACL Sprains

Predisposing factors– Intrinsic vs. extrinsic– Table 6-6, page 220

Signs and symptoms– Hearing and/or sensing a “pop”– Loss of function/limited ROM– Swelling (geniculate artery)

Intracapsular/extravasate

– Lachman’s test/anterior drawer test

ACL Sprains

Evaluative Findings– Table 6-7, page 221

Test PCL top rule out “false-positive” “partially torn ACL”

– Partial trauma leads to dysfunction, instability, increased stress on remaining fibers

– Predisposed to future injury

ACL-deficient knee– Susceptible to degenerative arthritis

ACL Sprains

Rehabilitation focuses on restoring ROM, lower extremity strength, proprioception– Knee braces

ACL reconstruction– To perform activities involving cutting and pivoting– Donor tissue options

Autografts vs. allografts

– Accelerated rehabilitation programs

ACL Injuries in Females

Experience a disproportionately high rate of noncontact ACL injuries relative to males

Predisposing factors (Table 6-6)– Narrower intercondyler notch widths

Phases of the menstrual cycle– Surging levels of estrogen and progesterone =

increased laxity– Risk increased 1 week before and 1 week after

start of cycle, when ACL is most lax

Posterior Cruciate Ligament Sprains

Damaged from:– Tibia being driven posteriorly on femur– Hyperflexion/hyperextension– Landing on anterior tibia while knee is flexed

Figure 6-23, page 222

Signs/symptoms– May be asymptomatic at first– s/s similar to strain of medial head os gastroc or

posterior capsule

PCL Sprains

Signs and symptoms– Pain in posterior knee– Weakness of hamstrings and quadriceps– Reduced ROM during flexion– Posterior drawer and sag tests– Increased instability when other posterior

structures are also damaged Evaluative Findings

– Table 6-8, page 222

PCL Sprains

Predisposing factors– Joint loading– Joint congruency– Muscular activity

Posterior laxity does not always result in knee dysfunction

Nonoperative treatment– May lead to chronic instability over time

Rotational Knee Instabilities

Multiplanar; involve abnormal internal or external rotation at tibiofemoral joint

Named based on relative direction in which the tibia subluxates on the femur

The axis of tibial rotation is shifted in the direction opposite that of the subluxation

Figure 6-24, page 223 Table 6-9, page 223

Rotational Knee Instabilities

Result when multiple structures are traumatized

Combined laxity of each structure is summed to mark degree of instability

Any injury to cruciate or collateral ligaments, joint capsule, IT band or biceps femoris may potentially result in rotational instability

Rotational Knee Instabilities

Signs and symptoms– “giving out”– Decreased muscle strength– Diminished performance– Lack of confidence in stability– Tests will often only produce positive results

under anesthesia

Anterolateral Rotatory Instability

Involves trauma to ACL and anterolateral capsule– LCL, IT band, biceps femoris, lateral meniscus,

posterolateral capsule

Anterior tibial displacement and internal tibial rotation

Many special tests to determine ALRI– Positive results should be referred to physician

ALRI

Slocum drawer test– ALRI (internal rotation) and AMRI (external

rotation)– Box 6-12, page 224

Crossover Test– Semifunctional; not as exact as other tests– Primarily for ALRI, but may be used for AMRI– Box 6-13, page 225

ALRI

Pivot shift test (lateral pivot shift)– Duplicates anterior subluxation and reduction that occurs

during functional activities in ACL-deficient knees– Box 6-14, page 226

Slocum ALRI test– Body weight used to fixate femur– Box 6-15, page 227

Flexion-rotation drawer test (FRD)– Stabilizes tibia, results in subluxation of femur– Box 6-16, page 228

Anteromedial Rotatory Instability

Injury involving ACL, MCL, and meniscus (more commonly lateral meniscus)

Variations of Slocum drawer test and crossover test

Posterolateral Rotatory Instability

Anterior displacement of lateral femoral condyle relative to tibia– Tibia externally rotates relative to femur– Amount of external rotation increase with flexion

Evaluative Findings– Table 6-10, page 229

External rotation test for PLRI– Box 6-17, page 230

Meniscal Tears

Result from rotation and flexion of knee, impinging the menisci between the articular condyles of tibia and femur

Lateral meniscus– More mobility = may develop tears secondary to

repeated stress McMurray’s test

– Box 6-18, page 231 Apley’s compression and distraction test

– Box 6-19, page 232

Meniscal Tears

Evaluative Findings– Table 6-11, page 233

“locking”, “clicking”, pain along joint line, “giving way”

Pain not be described if tear is in avascular zone

Osteochondral Defects

OCDs are fractures of the articular cartilage and underlying bone that are typically caused by compressive and shear forces

Medial femoral condyle most common; also lateral femoral condyle, tibial articulating surface, patella

Males affected more than females Figure 6-25, page 229

OCDs

Signs and symptoms– Masked by those of concurrent injury– Diffuse pain within knee– “locking”, “giving way”, “clunking”– Pain increased with weight-bearing activities– Increase in pain and decrease in strength in

closed kinetic chain vs. open chain

Wilson’s test – Box 6-20, page 234

OCDs

Conservative treatment– Modified activity

Surgical repair– Simple debridement or techniques to stimulate

fibrocartilage formation– Newer techniques – place newly grown articular

cartilage within defect, or transplant healthy cartilage form one area in knee to defect

Early protection phase in rehabilitation

Iliotibial Band Friction Syndrome

Friction between IT band and lateral femoral condyle

Occurs in sports that require repeated knee flexion and extension– Running, rowing, cycling

Bursa between IT band and lateral femoral condyle may become inflamed

IT Band Syndrome

Predisposing factors:– Genu varum – projects lateral femoral condyle

laterally, increasing friction– Pronated feet– Leg length differences– Conditions resulting in internal rotation alter angle

in which IT band attaches to Gerdy’s tubercle, increasing pressure at lateral femoral condyle

IT Band Syndrome

Evaluative Findings– Table 6-12, page 235

Noble’s compression test– Box 6-21, page 236

Ober’s test– Box 6-22, page 237

Treatment– Correct biomechanics, NSAIDs, modalities,

stretching, strengthening

Popliteus Tendinitis

Evaluative Findings– Table 6-13, page 238

Popliteus prevents a posterior shift of tibia on femur, running downhill places excessive strain on tendon

Figure-4 position – Figure 6-26, page 238 Treatment similar to other tendinitis

conditions

On-Field Evaluation of Knee Injuries

Equipment Considerations– Football pants– Knee brace removal

Figure 6-27, page 239

On-field History– Location of pain– Mechanism of injury– History of injury– Associated sounds and sensations– Associated neurologic symptoms

On-Field Evaluation of Knee Injuries

On-Field Inspection– Patellar position– Alignment of tibiofemoral joint

On-field Palpation– Extensor mechanism– MCL and medial joint line– LCL and lateral joint line– Fibular head

On-Field Evaluation of Knee Injuries

On-field Range of Motion Tests On-field Ligamentous Tests

– Valgus stress, varus stress, Lachman’s– Repeat after removing athlete from sideline

On-field Management of Knee Injuries

Tibiofemoral Joint Dislocations– Severe pain, muscle spasm, obvious deformity– Most occur with tibia sliding anteriorly over femur,

resulting in shortening of involved leg– Figure 6-28, page 241– Trauma to neurovascular structures = medial

emergency– Management – immobilization, verifying pulse,

shock, and activating EMS

On-field Management of Knee Injuries

Collateral and Cruciate Ligament Sprains– Compare bilaterally if possible– Remove from field in a non-weight-bearing

manner, if necessary– RICE, immobilization, referral, if necessary

Meniscal Tears– Evaluation based on athlete’s description of

mechanism of injury