Wilsons test (Knee)

Wilson’s test is a clinical examination used when osteochondritis dissecans (OCD) of the knee is suspected – a condition where an area of cartilage and underlying bone detaches from the femoral condyle. The test is primarily performed to identify pain caused by bony contact during specific motion patterns of the knee¹.

Clinical Anatomy

OCD most commonly affects the medial femoral condyle, particularly the weight-bearing region exposed to repetitive stress. This region articulates with the tibia when the knee is flexed and internally rotated. In OCD, localized necrosis develops, with possible detachment of a cartilage or osteochondral fragment².

Structures primarily involved:

• Subchondral bone of the medial femoral condyle

• Overlying articular cartilage

• Synovial capsule and intra-articular positioning

OCD occurs most frequently in adolescents and young athletes, requiring careful yet targeted clinical testing.

Test Procedure

Patient position:

• Patient sits on the edge of the table with the knee flexed to 90° and legs hanging freely.

• Examiner holds the foot and ankle, maintaining tibial internal rotation.

Execution:

• Patient is instructed to slowly extend the knee while tibia remains internally rotated.

• At approximately 30° from full extension, the examiner asks whether pain appears.

• If pain occurs, tibia is rotated back to neutral (external rotation).

Interpretation:

• Positive test: Localized knee pain around 30° extension in internal rotation that is immediately relieved by external rotation¹⁻³.

Practical Interpretation

• Pain arises when the osteochondral lesion or loose fragment impinges against the opposing articular surface during extension with internal rotation.

• External rotation relieves pressure on the affected area, eliminating pain.

• The test therefore reflects mechanical impingement of the lesion.

Clinical Considerations

Wilson’s test is:

• Most sensitive for OCD of the medial femoral condyle

• Less useful for lateral lesions or in the absence of mechanical impingement

• A cooperative test requiring clear patient feedback, unsuitable for acute swelling or severe pain

The test should be performed slowly with verbal guidance, as patient-reported pain localization is key for accurate interpretation.

Evidence and Limitations

To date, no validated studies systematically evaluating sensitivity, specificity, or inter-rater reliability for Wilson’s test exist⁴. Thus, it remains hypothesis-generating rather than a diagnostic gold standard.

Clinical recommendations:

• Use the test as an indication of possible OCD

• Always combine with history, examination, and MRI

• Do not rely solely on Wilson’s test for final diagnosis

Clinical Use Cases

Wilson’s test is typically used in:

• Adolescents and young adults with unexplained knee pain

• Activity-related symptoms without acute trauma

• Suspected mechanical symptoms such as locking or clicking

A positive test should prompt imaging referral, preferably MRI, to assess lesion size, stability, and potential need for surgical intervention.

Summary

Wilson’s test is a simple but under-validated clinical test for detecting OCD of the knee. When performed and interpreted correctly, it provides valuable clinical clues, but it should never be used in isolation. Its diagnostic value increases significantly when combined with imaging and a thorough patient history.

Sources:

1. Conrad JM, Stanitski CL. Osteochondritis dissecans: Wilson’s sign revisited. Am J Sports Med. 2003;31(5):777–778. https://doi.org/10.1177/03635465030310052301

2. Gjennomgått - trukket

3. Wilson JN. A diagnostic sign in osteochondritis dissecans of the knee. J Bone Joint Surg Am. 1967;49(3):477–480. https://doi.org/10.2106/00004623-196749030-00006

4. Wilson test