We prospectively assessed the diagnostic accuracy
of the gravity stress test and clinical findings to evaluate the stability
of the ankle mortise in patients with supination–external rotation-type
fractures of the lateral malleolus without widening of the medial
clear space. The cohort included 79 patients with a mean age of
44 years (16 to 82). Two surgeons assessed medial tenderness, swelling
and ecchymosis and performed the external rotation (ER) stress test
(a reference standard). A diagnostic radiographer performed the
gravity stress test. For the gravity stress test, the positive likelihood ratio (LR)
was 5.80 with a 95% confidence interval (CI) of 2.75 to 12.27, and
the negative LR was 0.15 (95% CI 0.07 to 0.35), suggesting a moderate
change from the pre-test probability. Medial tenderness, both alone
and in combination with swelling and/or ecchymosis, indicated a
small change (positive LR, 2.74 to 3.25; negative LR, 0.38 to 0.47),
whereas swelling and ecchymosis indicated only minimal changes (positive
LR, 1.41 to 1.65; negative LR, 0.38 to 0.47). . In conclusion, when gravity stress test results are in agreement
with clinical findings, the result is likely to predict stability
of the ankle mortise with an accuracy equivalent to
