📚 Course ContentsChapter 3 Clinical examination techniques for hip femur and knee injuries

3. Clinical examination techniques for hip femur and knee injuries

Imaging tells you what a structure looks like; the physical examination tells you what it does under load. In hip, femur, and knee assessment, palpation, range of motion (ROM), and special tests form a layered diagnostic sequence in which each stage narrows the differential before the next is applied. The clinician's goal is not to perform every test in the textbook but to select a coherent set whose results converge on a single plausible diagnosis. This chapter explains how to execute each component with reproducible technique, what a positive finding actually means, and how to interpret results when they conflict.

Palpation: Locating the Lesion by Anatomy, Not by Guesswork

Palpation begins with surface anatomy landmarks, because a tender point is only meaningful when it is referenced to a named structure. For the hip, the key landmarks are the greater trochanter, the ischial tuberosity, the pubic symphysis, the anterior superior iliac spine (ASIS), and the inguinal ligament. For the knee, they are the patella, the medial and lateral joint lines, the tibial tuberosity, the pes anserinus insertion, the fibular head, and the popliteal fossa.

Use a systematic sequence: superficial structures first, then deep. For the greater trochanter, palpate with the patient in lateral decubitus and the hip slightly flexed; point tenderness over the posterior-superior aspect suggests gluteus medius or minimus tendinopathy, while tenderness over the trochanteric bursa region suggests bursitis. For the knee, palpate the medial joint line with the knee flexed to about 30 degrees and the leg slightly externally rotated; focal tenderness here raises suspicion of a medial meniscal tear, whereas diffuse tenderness along the medial femoral condyle suggests MCL sprain. Always compare sides and record tenderness on a 0–10 scale with the exact anatomical location, since "knee pain" as a finding is clinically useless.

Palpation is most informative when performed before provocative testing. Provocative tests can produce guarding and generalized tenderness that mask the true focal lesion.

Range of Motion: Measuring What the Joint Can Do

ROM assessment has two purposes: establishing a baseline for comparison and detecting a mechanical block or capsular restriction. Use a goniometer and document active ROM (AROM) and passive ROM (PROM) separately. A clinically significant difference between AROM and PROM (for example, AROM 90 degrees flexion with PROM 130 degrees) points to a muscle-tendon problem rather than a joint restriction.

For the hip, normal values are approximately 120 degrees flexion, 30 degrees extension, 40 degrees internal rotation, 45 degrees external rotation, and 40 degrees abduction. For the knee, normal values are 0 degrees extension (with up to 5 degrees hyperextension) and 135–140 degrees flexion. Measure hip rotation with the patient supine and the hip in neutral; a reduction in internal rotation below about 15 degrees in a middle-aged patient is a classic early sign of hip osteoarthritis. For the knee, assess the extension lag by asking the patient to actively straighten the leg from a flexed position; an inability to reach full extension suggests quadriceps weakness or a mechanical block such as a displaced meniscal fragment.

Record ROM in a standard format so that serial examinations are comparable:

Hip (right): Flexion 110° (AROM) / 120° (PROM); Extension 20°; IR 10°; ER 35°; Abduction 35°
Knee (right): Extension -5° (lag 5°); Flexion 125° (AROM) / 135° (PROM)
End-feel: Hip — capsular (firm); Knee — soft tissue approximation

End-feel matters as much as the number. A hard, bony end-feel at the hip suggests osteoarthritis or a loose body; a springy block at the knee suggests a meniscal tear or a loose body caught in the joint.

Special Tests: Provocation With a Purpose

Special tests are provocative maneuvers designed to reproduce a specific structure's pain or instability. Their value depends on pretest probability: a test performed on a patient with a low likelihood of the condition produces mostly false positives. The table below summarizes the core tests for this region, their target structure, and the technique that produces a valid result.

Test	Target Structure	Technique and Positive Finding
FABER (Patrick)	Hip joint / sacroiliac	Supine, hip flexed, abducted, externally rotated; positive if pain is reproduced in the groin (hip) or posterior pelvis (SI joint).
FADIR	Femoroacetabular impingement	Supine, hip flexed to 90°, adducted, internally rotated; positive if anterior groin pain is reproduced.
Trendelenburg	Gluteus medius / hip abductors	Single-leg stance for 30 seconds; positive if the contralateral pelvis drops or the trunk leans toward the stance leg.
Lachman	ACL	Knee flexed 20–30°, femur stabilized, tibia translated anteriorly; positive if translation is increased with a soft end-point.
McMurray	Meniscus	Knee flexed, tibia internally or externally rotated, then extended; positive if a click or pain is felt at the joint line.
Valgus/Varus stress	MCL / LCL	Knee flexed 20–30°, apply valgus or varus force; positive if laxity or pain is reproduced at the respective ligament.

Execute each test slowly and compare with the uninjured side. For Lachman, the key is a soft end-point rather than absolute translation; a firm end-point with slight translation is often normal. For McMurray, the test is only meaningful when the knee is taken through a full arc of flexion to extension while maintaining rotation, and the finding must be localized to the joint line rather than the patellofemoral region.

Interpreting Conflicting Results

In practice, findings frequently disagree: a positive McMurray with a negative Lachman in a patient with medial knee pain, or a positive FABER with normal hip ROM. The correct response is not to average the results but to reassess three things. First, verify technique — most false positives come from poor positioning, insufficient relaxation, or failure to compare sides. Second, reconsider pretest probability: a positive FADIR in a 22-year-old athlete with groin pain carries far more weight than the same finding in a 70-year-old with diffuse hip pain. Third, use the examination to decide whether imaging is warranted, not to replace it. A negative Lachman in an acutely swollen knee with a tense hemarthrosis should still prompt MRI if the mechanism suggests ACL injury, because guarding can mask instability.

Do not perform provocative special tests on a patient with an acute fracture, suspected dislocation, or unstable hemodynamics. In suspected femoral neck fracture, the examination is limited to inspection, gentle neurovascular assessment, and imaging; forceful ROM testing can displace a nondisplaced fracture.

Documenting the Examination

A defensible record captures the sequence, the technique, and the comparison. A practical template for this region is:

Inspection: alignment, swelling, gait, scars
Palpation: focal tenderness (site, 0–10), temperature, effusion
ROM: AROM/PROM in degrees, end-feel, AROM–PROM gap
Special tests: test name, side, result (positive/negative), pain vs laxity
Neurovascular: distal pulses, sensation, motor
Working diagnosis and plan: imaging, weight-bearing status, referral

The examination is complete when the findings converge on a working diagnosis that explains the mechanism, the tenderness, the ROM restriction, and the provocative test result. When they do not converge, the honest entry is "examination inconclusive — imaging required," which is a clinically valid endpoint rather than a failure of technique.