The Proximal Tibiofibular Joint: A Biomechanical Analysis of the Anterior and Posterior Ligamentous Complexes.

BACKGROUND: Dislocation of the proximal tibiofibular joint is a complex injury that is often overlooked or misdiagnosed. Surgical management is recommended for severe acute or for chronic symptomatic instability of the proximal tibiofibular joint. Although the anterior ligamentous complex has been reported to be stronger than the posterior complex, biomechanical data are lacking.

PURPOSE: To determine the ultimate load of the anterior and posterior ligamentous complexes of the proximal tibiofibular joint to determine optimal graft selection.

STUDY DESIGN: Controlled laboratory study.

METHODS: Ten nonpaired, fresh-frozen knee specimens were dissected to expose the anterior and posterior proximal tibiofibular ligamentous complexes. The tibia was split in the coronal plane to separate the anterior and posterior ligamentous complexes, and the fibula was left intact. Specimens were secured in a dynamic testing machine and preconditioned for 10 cycles between 2 and 10 N at 0.1 Hz followed by loading to failure at a rate of 25 mm/min.

RESULTS: The mean (±SD) ultimate load of the anterior complex (517 ± 144 N) was significantly greater than the mean ultimate load of the posterior complex (322 ± 160 N) ( P = .012). The mean surface areas of the anterior and posterior complexes were 761 ± 174 mm2 and 565 ± 103 mm2 , respectively ( P = .008). The mean values for stiffness of the anterior (133 N/mm) and posterior (109 N/mm) complexes were similar ( P = .250).

CONCLUSION: The ligaments of the human proximal tibiofibular joint were able to withstand a mean ultimate failure load of 517 ± 144 N for the anterior complex and 322 ± 160 N for the posterior complex. In this regard, it is recommended that the strengths of grafts chosen for proximal tibiofibular reconstructions meet or exceed these values.

CLINICAL RELEVANCE: The optimal surgical treatment for addressing residual proximal tibiofibular instability is not well defined. Before an anatomic reconstruction of the proximal tibiofibular ligament is developed, the individual biomechanical properties of the anterior and posterior ligamentous structures of the proximal tibiofibular joint need to be considered to facilitate an optimal reconstruction design.