Lower Limb Examination OSCE — Hip, Knee, Ankle and Special Tests

Why This Station Is Tested

Lower limb musculoskeletal examination is tested across both primary and surgical care OSCE circuits. It evaluates your ability to use the look-feel-move framework systematically, perform special tests of the knee, screen for vascular and neurological complications, and generate a clinically relevant differential. The knee is the most frequently examined individual joint.

Before You Begin

Introduce yourself, confirm patient identity, obtain consent, and expose both lower limbs fully (shorts or with gown for modesty). Ask about pain before touching. Observe the patient walking into the examination room (gait screen) — this is often a mark-scheme point.

General Inspection (Standing and Walking)

Gait Assessment

Ask the patient to walk to the end of the room and back. Observe:

• Antalgic gait: short stance phase on the painful side (pain-relieving limp)
• Trendelenburg gait: hip abductor weakness — contralateral pelvis drops during single-leg stance (positive Trendelenburg)
• High-stepping gait: foot drop (L4/5 or peroneal nerve palsy)
• Scissor gait: bilateral spasticity (UMN)

Standing Inspection

• Alignment: genu varum (bow-legged — lateral compartment OA), genu valgum (knock-kneed — medial compartment OA/RA)
• Quadriceps wasting (visible especially around the VMO)
• Skin: erythema, scars, swelling
• Feet: pes planus (flat foot), pes cavus, hallux valgus

The Knee — Focus Area

Look

Supine position. Compare both knees. Inspect for: swelling (effusion — loss of medial dimple; patellar tap will be positive); erythema and warmth (septic arthritis, gout, haemarthrosis); muscle wasting above the knee (VMO); skin changes (psoriasis patches — psoriatic arthritis); varus/valgus deformity; scars from previous surgery.

Feel

Skin temperature (dorsum of hand, compare sides). Palpate systematically:

• Joint line (medial and lateral) — tenderness suggests meniscal pathology or compartment OA
• Patella and its edges — patellar tap for large effusion; bulge test (patella sweep) for small effusion
• Ligaments: medial collateral (MCL) and lateral collateral (LCL) along their course
• Popliteal fossa: Baker's cyst (bursitis — communicates with joint in RA and OA)

Effusion tests:

• Patellar tap: compress the suprapatellar pouch with one hand to displace fluid under the patella, then tap the patella sharply — a "click" on impact = positive (large effusion, >15 mL)
• Bulge/wipe test: wipe the medial compartment dry, then apply pressure to the lateral side — a fluid wave or bulge returns to the medial compartment (small effusion, 10–15 mL)

Move

Active range of movement first (asks patient), then passive (you move the joint):

• Flexion: normal 0–140°
• Extension: normal 0° (full extension); fixed flexion deformity = cannot fully extend

Special Tests — Knee

Lachman test technique: Patient supine, knee flexed 20–30°. Stabilise the femur with one hand, grip the proximal tibia with the other, and apply an anterior translating force — positive if tibia moves forward with a soft or absent end-feel.

McMurray test technique: Knee in full flexion. For medial meniscus: externally rotate the tibia and apply valgus stress whilst slowly extending the knee — click or pain at the medial joint line = positive. For lateral meniscus: internally rotate and valgus stress.

Hip Examination

Look

Leg length discrepancy (apparent — from pelvic tilt; true — measure ASIS to medial malleolus), hip flexion deformity.

Feel

Palpate over greater trochanter (bursitis), hip joint line (groin — deep palpation), and iliopsoas.

Move

• Flexion (normal 120°): Thomas test for fixed flexion deformity — flatten the lumbar lordosis, flex the opposite hip maximally — contralateral leg rising off the bed = positive FFD
• Internal rotation (normal 30°) and external rotation (45°): performed with hip and knee flexed to 90°; limited painful internal rotation is an early sign of hip pathology (OA, AVN, septic arthritis)
• Abduction (45°) and adduction (30°)
• Extension (assessed prone, 10–15°)

FABER test (Flexion, ABduction, External Rotation): figure-of-four position — pain in the groin = hip pathology; pain in the sacroiliac region = SIJ pathology.

Ankle Examination

• Look: swelling (lateral — inversion injury, ligament sprain; medial — deltoid ligament, syndesmosis), bruising, deformity
• Feel: anterior talofibular ligament (ATFL — most commonly injured), calcaneo-fibular ligament, posterior talofibular ligament, medial malleolus, base of 5th metatarsal (avulsion fracture)
• Ottawa rules: X-ray if bony tenderness at the posterior 6cm of the fibula or medial malleolus, or if unable to weight-bear 4 steps
• Move: dorsiflexion (normal 20°), plantarflexion (50°), inversion/eversion
• Special: anterior drawer test of the ankle (ATFL integrity)

Vascular and Neurological Screen

Always complete a lower limb examination with:

• Peripheral pulses (dorsalis pedis, posterior tibial)
• Capillary refill time
• Sensation (light touch, pinprick at L3, L4, L5, S1 dermatomes)
• Power screen (ankle dorsiflexion L4/5, plantarflexion S1/2)
• Reflexes (knee L3/4, ankle S1/2)

Frequently Asked Questions

"How do I perform the Lachman test and what does a positive result indicate?"

The Lachman test is the most sensitive clinical test for ACL rupture (sensitivity ~85%, specificity ~94%), and is more reliable than the anterior drawer test because the hamstrings are relaxed at 20–30° flexion but tense at 90°. Technique: position the patient supine with the knee flexed to 20–30°. Stabilise the distal femur with one hand (thumb over the lateral femoral condyle). With the other hand, grip the proximal tibia (thumb over the tibial tuberosity) and apply a firm anterior translating force. A positive test shows anterior translation of the tibia relative to the femur of more than 3 mm AND a soft or absent end-feel — in an intact ACL, the end-feel is firm (the ligament tightens and arrests movement). Grade the degree of anterior translation: 1+ = 3–5mm, 2+ = 5–10mm, 3+ = >10mm. A positive Lachman in the acute setting with haemarthrosis is highly suggestive of ACL rupture — MRI is the definitive investigation to confirm and assess associated meniscal injuries (ACL tears are commonly associated with medial meniscal tears and MCL injuries — the "unhappy triad").

"What is the difference between the anterior drawer test and the Lachman test for assessing the ACL?"

Both tests assess ACL integrity by applying anterior tibial translation relative to the femur, but they differ in knee flexion angle and reliability. The anterior drawer test is performed at 90° knee flexion — the examiner sits on the patient's foot to stabilise, places both hands around the upper tibia, and pulls anteriorly. At 90° of flexion, the hamstrings are stretched and may limit anterior translation, reducing test sensitivity (approximately 38–62%), particularly in acute injuries where pain and muscle spasm are present. The Lachman test is performed at 20–30° flexion, where hamstring tension is minimal, giving significantly higher sensitivity (~85%) and making it the preferred test in clinical practice. In the OSCE, perform Lachman first (most sensitive) and then the anterior drawer if the examiner specifically asks. Note that the posterior drawer test (pushing the tibia posteriorly at 90°) assesses the posterior cruciate ligament — look for a posterior sag of the tibia before performing this test, which itself indicates PCL rupture.

"How do I detect a knee effusion clinically and what does the presence of one tell you?"

There are two main bedside tests for knee effusion. The patella tap (ballottement) detects large effusions (>15 mL): compress the suprapatellar pouch with one hand to displace any fluid beneath the patella, then tap the patella sharply with one finger of the other hand — a palpable click as the patella strikes the femoral condyles and bounces back ("balloting") is positive. The bulge or wipe test detects small effusions (10–15 mL): stroke firmly from the medial compartment upwards (wiping fluid out), then stroke the lateral side downwards — a visible or palpable fluid wave returning to the medial compartment is positive. The clinical significance of an effusion depends on its characteristics: acute traumatic haemarthrosis (immediate swelling post-injury, often ACL rupture, tibial plateau fracture, or patellar dislocation), reactive effusion (inflammatory — RA, reactive arthritis, gout), infective (septic arthritis — hot, red, exquisitely tender joint — requires urgent aspiration and antibiotics), and osteoarthritic effusion (subacute, less pronounced). Aspiration of the fluid for analysis (cell count, crystals, culture, protein) is the definitive investigation.

"What is the McMurray test and how do you perform it correctly?"

The McMurray test assesses meniscal integrity by applying a compressive rotational stress to the knee. Technique: lay the patient supine and fully flex the knee. For the medial meniscus: externally rotate the tibia (foot turned outward) and apply a valgus stress (push the knee into valgus), then slowly extend the knee from full flexion. A positive test produces a palpable or audible click and/or pain at the medial joint line as the torn meniscal fragment is caught between the femoral condyle and tibial plateau. For the lateral meniscus: internally rotate the tibia and apply varus stress while extending. The McMurray test has moderate sensitivity (~55%) and high specificity (~77%) — a negative test does not exclude a meniscal tear. Other meniscal signs: Apley's compression test (prone, knee at 90°, compress and rotate — meniscal injury = pain; distract and rotate — ligament injury = pain), and joint line tenderness on palpation (most sensitive sign for meniscal pathology). MRI is the gold-standard investigation for suspected meniscal pathology.

"What are the Ottawa Ankle Rules and when should you apply them in the OSCE?"

The Ottawa Ankle Rules (OAR) are a validated clinical decision tool (sensitivity ~96–100% for fracture) that guide whether ankle X-rays are needed after an acute ankle injury. An ankle X-ray series is required only if there is pain in the malleolar zone AND any of: (1) bony tenderness at the posterior edge or tip of the lateral malleolus (distal 6 cm), (2) bony tenderness at the posterior edge or tip of the medial malleolus (distal 6 cm), or (3) inability to weight-bear for 4 steps both immediately after the injury and in the emergency department. A foot X-ray series is required only if there is pain in the midfoot zone AND: (4) bony tenderness at the base of the 5th metatarsal (avulsion fracture by peroneus brevis), or (5) bony tenderness over the navicular bone, or (6) inability to weight-bear. The OAR should NOT be applied in children under 18 (growth plates make clinical assessment unreliable), in patients with diminished sensation (e.g., diabetic neuropathy), in intoxicated patients, or if there are multiple painful injuries. In the OSCE, citing and applying the OAR when examining an ankle injury demonstrates evidence-based clinical reasoning.

"How do I present lower limb musculoskeletal examination findings to an examiner?"

Present systematically using the LOOK-FEEL-MOVE framework, comparing sides throughout. Start with your overall impression: "On general inspection, this patient has a right-sided antalgic gait, suggesting pain in the right lower limb." Then work through each component: "On inspection of the knees, there is a visible effusion on the right with loss of the medial dimple and mild quadriceps wasting. Skin is warm to the touch over the right knee compared with the left. On palpation, there is medial joint line tenderness and a positive patellar tap consistent with a moderate effusion. Active and passive flexion is limited on the right to 100° with a firm end-feel; extension is full. Special tests: McMurray is positive on the right for medial meniscal pathology with pain and a click at the medial joint line. Lachman test is negative bilaterally. Valgus and varus stress tests are negative. Peripheral pulses, sensation, and power are intact bilaterally." Conclude with: "These findings are consistent with a right medial meniscal tear with associated effusion, most likely following the recent sporting injury the patient described." This structured, comparative, and concluding approach is what the mark scheme rewards.

Related guides: Knee Examination OSCE · Hip Examination OSCE · Ankle Examination OSCE · Gait Assessment OSCE · Lower Limb Neurological Examination OSCE