Painful catch sign: The patient lies supine and the therapist lifts both lower extremities by the ankle. The knees are kept extended and the therapist releases the ankles. The patients attempts to hold the legs up, and if the lower extremities fall instantly over the table because of back pain, the test is positive for lumbar instability. Watch also for jerky, painful movements while the patient lowers their legs to the table.
Note: The original test requires the patients to lift the legs on their own, but many patients with a lumbar instability will find it too difficult.
Reported to have 37% sensitivity and 73% specificity (Kasai et al. 2006).