• Harri Pakarinen, Tapio Flinkkilä, Pasi Ohtonen, Pekka Hyvönen, Martti Lakovaara, Juhana Leppilahti, and Jukka Ristiniemi.
• Division of Orthopedic and Trauma Surgery, Department of Surgery, Oulu University Hospital, P.O. Box 21, FI 90029 OYS, Oulu, Finland. harri.pakarinen@ppshp.fi
• J Bone Joint Surg Am. 2011 Nov 16;93(22):2057-61.

BackgroundThis study was designed to assess the sensitivity, specificity, and interobserver reliability of the hook test and the stress test for the intraoperative diagnosis of instability of the distal tibiofibular joint following fixation of ankle fractures resulting from supination-external rotation forces.MethodsWe conducted a prospective study of 140 patients with an unstable unilateral ankle fracture resulting from a supination-external rotation mechanism (Lauge-Hansen SE). After internal fixation of the malleolar fracture, a hook test and an external rotation stress test under fluoroscopy were performed independently by the lead surgeon and assisting surgeon, followed by a standardized 7.5-Nm external rotation stress test of each ankle under fluoroscopy. A positive stress test result was defined as a side-to-side difference of >2 mm in the tibiotalar or the tibiofibular clear space on mortise radiographs. The sensitivity and specificity of each test were calculated with use of the standardized 7.5-Nm external rotation stress test as a reference.ResultsTwenty-four (17%) of the 140 patients had a positive standardized 7.5-Nm external rotation stress test after internal fixation of the malleolar fracture. The hook test had a sensitivity of 0.25 (95% confidence interval, 0.12 to 0.45) and a specificity of 0.98 (95% confidence interval, 0.94 to 1.0) for the detection of the same instabilities. The external rotation stress test had a sensitivity of 0.58 (95% confidence interval, 0.39 to 0.76) and a specificity of 0.96 (95% confidence interval, 0.90 to 0.98). Both tests had excellent interobserver reliability, with 99% agreement for the hook test and 98% for the stress test.ConclusionsInterobserver agreement for the hook test and the clinical stress test was excellent, but the sensitivity of these tests was insufficient to adequately detect instability of the syndesmosis intraoperatively.

40 keywords...

hide…