Influence of Tönnis grade on outcomes of arthroscopy for FAI in athletes: a comparative analysis

Based on a previously reported study, it is hypothesized that Tönnis 2 changes may not be a harbinger of poor results. The purpose is to report outcomes comparing Tönnis 2 changes to those with Tönnis 0&1 changes. Previously published outcomes (modified Harris Hip Score and return to sport) among 200 consecutive athletes undergoing arthroscopic correction of femoroacetabular impingement with minimum 1-year follow-up were correlated with the Tönnis grade. Independent variables of gender and age were also evaluated. Average age was 28.6 years (range 11–60), with 148 males and 52 females. The average improvement was Tönnis 0 23.1 points (n = 37), Tönnis 1 20.6 points (n = 113) and Tönnis 2 16.4 points (n = 48). A trend (P = 0.055) towards lower scores with increasing Tönnis grade was not statistically significant. There was both statistically (P < 0.01) and clinically (>8 patients) significant improvement across all Tönnis grades, and there was no statistically significant difference between Tönnis 0 and 1 compared with Tönnis 2 (P = 0.078). The percent that returned to sport was as follows: Tönnis 0 95%, Tönnis 1 92% and Tönnis 2 85%. A trend (P = 0.098) towards lower rates of return to sport with increasing Tönnis grade was not statistically significant, and there was no statistically significant difference between Tönnis 0 and 1 compared with Tönnis 2. Within each grade, there was no correlation with age, such that increasing age did not reflect lower scores. There was also no correlation with gender. Statistically and clinically successful outcomes can be encountered among athletes with Tönnis 2 radiographic features.