Anterior lateral ankle ligament damage and anterior talocrural-joint laxity: an overview of the in vitro reports in literature

Objective. To provide a clear overview of the literature on the relationship between increased lateral ankle ligament damage and anterior talocrural-joint laxity. Design. A systematic review of the literature. Background. Diagnostic methods for inversion injuries of the ankle have remained controversial throughout the years. An instrumented test for anterior talocrural-joint laxity could be a diagnostic toot for evaluation of anterior lateral ankle ligament function. Methods. An advanced electronic database search using MEDLINE and EMBASE was performed to find studies describing the correlation between lateral ankle ligament damage and talocrural-joint laxity. Two reviewers assessed the methodological quality for each study and agreement was noted. Two reviewers extracted all relevant data with respect to methodology, motion constraints and laxity measurement. Results. The quality assessment resulted in 5 studies being scored as high quality and 5 as low quality. Different test devices were used to apply the load and measure the displacement. All in vitro tests applied a load to the calcaneus and subsequently measured the translation of the talus and/or calcaneus relative to the tibial dome. Rotation in the transversal and frontal plane was restricted in 8 tests. After analysis of the results presented by nine different studies, the mean value of anterior talocrural-joint laxity with intact ligaments is 4.2 mm. After sectioning of the anterior talofibular ligament, the mean anterior laxity value is 6.5 mm. The mean anterior laxity value after sectioning of the calcaneofibular ligament increases to 8.4 mm. The mean anterior laxity value with the foot in dorsal flexion (3.1 mm) is less than the mean value with the foot in neutral position (4.5 mm) or in plantar flexion (4.7 mm). The applied load and the anterior laxity values between the different studies vary greatly. Conclusions. Each ligament section results in significantly increased talocrural-joint laxity. Talocrural-joint laxity can be used as a measure for damage to the anterior talofibular ligament and/or the calcaneofibular ligament. From this review, it is neither possible to give universal recommendations about the optimal flexion angle for testing talocrural-joint laxity as a measure for lateral ankle ligament function, nor to recommend the ideal load for performing the test.