PRONE INSTABILITY TEST
ICF category	Measurement of impairment of body function – pain in back; pain in lower limb; mobility of joint functions, specified as mobility in a vertebral segment, control of complex voluntary movements
Description	The patient lies prone with the body on the examining table, legs over the edge and feet resting on the floor. While the patient rests in this position, the examiner applies posterior-to-anterior pressure to spinous processes of the lower portion of the lumbar spine. Any provocation of pain is noted. Then the patient lifts the legs off the floor (the patient may hold table to maintain position) and posterior-to-anterior pressure is again applied to the lumbar spine.
Measurement Method	Positive Test - If pain is present in the resting position but subsides substantially (either reduces in severity/intensity, or resolves) in the second position, the test is positive. Mild improvement in symptoms does not constitute a positive test. Negative Test - If pain is present in the resting position, but does not subside substantially in the second position, the test is negative. Further, if the patient did not have any pain provocation with posterior-to-anterior pressures applied to the lumbar spine, then the test is judged “negative.”
Nature of variable	Positive or negative
Units of measurement	Categorical
Diagnostic accuracy and measurement properties	Kappa is reported good to excellent agreement (k=0.87)146 in 3 pairs of physical therapy raters evaluating 63 consecutive subjects currently experiencing LBP and with a previous history of LBP. As an independent test the Prone Instability Test has limited diagnostic use (+LR=1.7 (95% CI=1.1–2.8), −LR=0.48(95% CI=0.22–1.1),145 however, it may be most useful as component of a cluster of tests to predict response to motor control exercises145.