2.2 Knee, Hip & Lower Extremity Conditions

2.2 Knee, Hip & Lower Extremity Conditions

Lower extremity musculoskeletal conditions are major sources of pain and functional disability managed by PM&R physicians. Establishing a precise diagnosis requires integrating functional biomechanics with validated physical examination maneuvers.

Meniscus Tear Diagnostics

The menisci provide load transmission, shock absorption, joint lubrication, and secondary stability to the knee. Meniscal vascularity is divided into three zones: outer red-red zone (vascular, high repair potential), middle red-white zone, and inner white-white zone (avascular, managed with partial meniscectomy).

Clinical Physical Examination Tests

• Joint Line Tenderness: Palpation along medial and lateral tibiofemoral joint lines possesses the highest overall sensitivity (~83-85%) for meniscal pathology.
• McMurray Test: Patient supine with hip and knee flexed. For medial meniscus, examiner externally rotates tibia with valgus stress while extending knee. For lateral meniscus, examiner internally rotates tibia with varus stress while extending knee. Positive finding is palpable/audible click or joint line pain.
• Thessaly Test: Weight-bearing test performed with patient standing on one leg flexed to 20°. Patient rotates body internally and externally three times. Repetition of joint line pain or locking has highest overall diagnostic accuracy (~89-94%).
• Apley Grind Test: Patient prone with knee flexed 90°. Examiner applies axial compression while rotating tibia. Pain indicates meniscal injury.

Knee Ligamentous Stability Testing

Knee stability depends on the anterior cruciate ligament (ACL), posterior cruciate ligament (PCL), medial collateral ligament (MCL), and lateral collateral ligament (LCL).

ACL Testing

• Lachman Test: Performed with knee flexed 20–30°. Examiner stabilizes distal femur and pulls proximal tibia anteriorly. It is the most sensitive test (~95%) for ACL rupture.
• Pivot Shift Test: Highly specific test for ACL insufficiency evaluating rotatory instability. Valgus stress and internal rotation applied to extended knee while flexing; at 20–30° flexion, subluxated anterior tibia reduces posteriorly via iliotibial band traction.
• Anterior Drawer Test: Performed at 90° knee flexion; less sensitive than Lachman due to hamstring spasm and meniscus blocking displacement.

PCL and Collateral Testing

• Posterior Drawer Test: Performed at 90° flexion; most sensitive maneuver for isolated PCL tears.
• Posterior Sag Sign (Godfrey Test): Patient supine with hips/knees flexed 90°. Posterior dropping of proximal tibia relative to femur indicates PCL insufficiency.
• Dial Test: Measures passive tibial external rotation at 30° and 90° knee flexion. Increased rotation (>10°) at 30° only indicates isolated Posterolateral Corner (PLC) injury. Increased rotation at both 30° and 90° confirms combined PCL and PLC injury.
• Valgus / Varus Stress Testing: Evaluated at 0° (testing collateral plus cruciate/capsular restraints) and 30° flexion (isolating MCL with valgus stress or LCL with varus stress).

Patellofemoral Pain Syndrome (PFPS)

Patellofemoral Pain Syndrome (PFPS) is characterized by retropatellar or peripatellar pain resulting from altered patellofemoral joint mechanics and excessive focal cartilage stress.

Biomechanical Etiology and Risk Factors

Contributing factors include vastus medialis obliquus (VMO) weakness, tight lateral retinaculum, tight hamstrings/gastrocnemius, increased Q-angle (>15° men, >20° women), foot pronation, and weak hip abductors/external rotators.

Clinical Manifestations and Exam

Pain aggravated by stair descent, squatting, running, and prolonged sitting with flexed knees ("theater sign").

• Patellar Compression (Clarke) Test: Pressing patella inferiorly into trochlea while contracting quadriceps.
• Patellar Tilt Test: Elevation of lateral patellar border; inability to tilt above horizontal indicates tight lateral retinaculum.
• Rehabilitation: Focuses on hip abductor/gluteus medius strengthening, core stability, VMO activation, and patellar taping (McConnell taping).

Hip Osteoarthritis and Labral Pathology

Hip disorders manifest as anterior groin pain radiating to the anterior thigh or knee (obturator nerve distribution).

Hip Osteoarthritis (OA)

Characterized by progressive cartilage loss, subchondral sclerosis, osteophytes, and joint space narrowing (typically superior/anterior). Exam reveals restriction of passive range of motion in a capsular pattern: Internal Rotation and Flexion are lost first.

Femoroacetabular Impingement (FAI) and Labral Tears

• Cam Impingement: Aspherical femoral head-neck junction bump.
• Pincer Impingement: Acetabular overcoverage.
• FADIR Test (Flexion, ADduction, Internal Rotation): Highly sensitive screening maneuver for anterior labral tears and FAI. Groin pain indicates a positive test.
• FABER / Patrick Test (Flexion, ABduction, External Rotation): Posterior hip/SI joint pain indicates sacroiliac dysfunction; anterior groin pain indicates intra-articular hip pathology.

Greater Trochanteric Pain Syndrome (GTPS)

Greater Trochanteric Pain Syndrome (GTPS) primary pathology is gluteus medius and gluteus minimus tendinopathy or tear, with secondary bursa inflammation.

Clinical Signs and Diagnosis

• Point tenderness over posterior aspect of greater trochanter.
• Pain provoked by resisted hip abduction and passive hip adduction.
• Single-Leg Stance Test: Standing on affected leg for 30 seconds reproduces lateral hip pain (high specificity ~92%).
• Trendelenburg Sign: Weakness of stance-phase gluteus medius causes contralateral pelvic drop.

Plantar Fasciitis

Plantar fasciitis is a degenerative enthesopathy at the origin of plantar aponeurosis on the medial calcaneal tubercle.

Biomechanics and Clinical Presentation

Plantar fascia functions via Windlass mechanism: passive dorsiflexion of hallux winds plantar fascia around first metatarsal head, elevating longitudinal arch.

• Hallmark Symptom: Severe post-static dyskinesia—pain with first steps in morning or after sitting, which improves after warming up.
• Exam: Point tenderness over anteromedial calcaneus; pain reproduced by passive toe dorsiflexion.
• Management: Stretching plantar fascia and calf muscles, night splints (5° dorsiflexion), custom orthotics, and physical therapy.