[Impact of temporomandibular joint arthroscopic discopexy on condylar growth in adolescents: a retrospective cohort study].

To compare changes of condylar height, disc length and displaced distance in adolescent temporomandibular joint (TMJ) disc displacement with or without arthroscopic discopexy. From September 2015 to November 2018, adolescents with magnetic resonance image (MRI) comfirmed disc displacement without reduction (DDwoR) were recruited in operation group (OG) and control group (CG) and were classified into five subgroups according to age (11-14 years, 15-16 years, 17-18 years, 19-20 years and 21-24 years). Changes of condylar height, disc length and displaced distance were measured before and after follow-up MRI. Student's test, Welch's test, Mann-Whitney test, Wilcoxon signed-rank test, One-way ANOVA and Kruskal-Wallis test were used; -value less than 0.05 was considered statistically significant. One hundred and seventy two patients were recruited in the present study. One hundred and twenty six cases patients (183 joints, 17 males, 109 females, mean age 17.4±3.0 years) were in OG and 119 patients (175 joints, 20 male, 99 females, mean age 17.1±3.1) in CG. The mean follow-up time were 8.4 (2.7-22.0) and 9.5 (3.0-22.1) months respectively. Average condylar height changes of OG were significantly greater than CG (1.3±1.8 mm -0.6±1.5 mm, 0.001) and differences were also seen in each age group (0.001). In terms of age variations, average increase of condylar height in OG were (2.4±2.2) mm, (1.3±1.7) mm, (1.6±1.7) mm, (0.8±1.9) mm, (0.4±1.1) mm respectively (0.001), differences were observed between 11-14 years 19-20 years (<0.05), 11-14 years 21-24 years (<0.01) and 17-18 years 21-24 years (<0.01) subgroups; and average changes in CG were (-0.7±1.6) mm, (-0.4±1.6) mm, (-0.8±1.5) mm, (-0.3±1.4) mm and (-0.9±1.5) mm respectively (0.05). After follow-up in CG, further displaced disc was observed (0.05) while disc length remained unchanged (0.05). DDwoR in adolescents resulted in decreased TMJ condylar height while arthroscopic discopexy restored growth potential and promoted condylar new bone formation which was most prominent during growth period.