Early detection of joint degeneration in the subtalar and talonavicular joints secondary to ankle instability in a mouse model

Abstract Background Many patients with ankle sprain have secondary subtalar and talonavicular injuries, which have a great impact on their life and body. Purpose: This study aimed to investigate the biomechanical impact of ankle instability on the subtalar joint (STJ) and talonavicular joint (TNJ) using a mouse model to enhance the clinical understanding of early stage secondary joint degeneration. Methods Twenty four 8-week old male C57BL/6 ​J mice were randomly allocated to three groups. Both the calcaneofibular ligament (CFL) and anterior talofibular ligament (ATFL) of the left ankle were cut off in the CFL ​+ ​ATFL group to simulate severe ankle instability while only the CFL was excised in the CFL group to mimic moderate ankle instability. No operation was done in SHAM group to simulate the normal ankle. Then histological analysis, atomic force microscopy (AFM) – based nanoindentation tests and inspection by scanning electron microscopy (SEM) were used to assess the degree of joint degeneration in the tibiotalar joint (TTJ), STJ and TNJ of three groups. Results A significant increase of histological score for both CFL and CFL ​+ ​ATFL group was demonstrated in the TTJ, compared with the SHAM group. While in the STJ and TNJ, the histological score only increased for CFL ​+ ​ATFL group. AFM-based nanoindentation results demonstrated significant differences in elastic modulus between all groups in the TTJ, while for the STJ and TNJ, only the comparison between the CFL ​+ ​ATFL group and SHAM group was considered statistically significant. The SEM presented signs of cracking and disintegration within the subchondral bone (SCB) interface in the CFL ​+ ​ATFL group only. Conclusions The findings indicate that severe ankle instability resulted in early degeneration of the STJ and TNJ in a mouse model, which may provide referential values for clinical practice.