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 20 o – 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