Execution
- 1Position the patient supine with the knee extended and quadriceps relaxed.
- 2Place the web space or hand just superior to the patella.
- 3Apply gentle inferior and posterior pressure to the patella against the femur.
- 4Ask the patient to contract the quadriceps.
- 5Note pain, crepitus, inability to contract, or apprehension.
Positive outcome
Retropatellar pain or inability to maintain quadriceps contraction because of pain is positive. Crepitus may occur but is not diagnostic by itself. The test is commonly associated with patellofemoral pain or chondromalacia but has poor specificity.
Studies
| Study | Reliability | Sn | Sp | LR+ | LR− |
|---|---|---|---|---|---|
| Cook et al. (2010) | NA | 39 | 67 | 1.18 | 0.91 |
CommentClarke's sign is notorious for provoking pain in asymptomatic knees and should not be used as a stand-alone patellofemoral diagnosis. Magee includes it historically, but modern evidence favors symptom behavior and clusters over grind testing. Use gentle pressure only, if at all.
Low Clinical Value