Effect of ligamentum teres tear on the development of joint instability and articular cartilage damage: an in vivo rabbit study

The contribution of the ligamentum teres to the stabilization of the hip joint and the clinical influence of a compromised ligamentum teres are not well known. This study aimed to investigate joint stability and cartilage damage in a rabbit model by surgically inducing a complete ligamentum teres tear. Twenty adult New Zealand rabbits were used in this study. Rabbits were divided into complete ligamentum teres tear with capsulotomy (n = 9, group I) and capsulotomy only (n = 10, group II) groups. Unilateral surgery was performed on the left hip. Joint instability was assessed by measuring the preoperative and postoperative acetabulofemoral (A-F) distances. Rabbits were euthanized to assess cartilage damage at 24 weeks postoperatively. The median postoperative A-F distance of the operated side in group I [0.68 cm (0.37–1.04 cm)] was larger than that in group II [0.50 cm (0.30–0.65 cm)] (p = 0.041). The median postoperative A-F distance was larger in the operated side [0.68 cm (0.37–1.04 cm)] compared to the nonoperated side [0.45 cm (0.30–0.75 cm)] in group I; it also was larger in the operated side [0.50 cm (0.30–0.65 cm)] compared to the nonoperated side [0.44 cm (0.32–0.67 cm)] in group II, but only group I showed a significant difference (p = 0.016 and 0.395, respectively). Articular cartilage damage was detected at the apex of the femoral head in two rabbits (22.2%) in group I only. Rabbits with a complete ligamentum teres tear showed significant instability at the hip joint and articular cartilage damage in our rabbit model, supporting the potential clinical importance of ligamentum teres as a hip joint stabilizer.