Preoperative and postoperative shoulder position sense in patients who underwent arthroscopic Bankart repair for traumatic shoulder joint instability

BACKGROUND: Proprioceptive feedback is a reflex dislocation prevention mechanism that contributes to shoulder joint stability. In patients with Bankart lesions, the anteroinferior glenohumeral ligament complex is damaged and reduces the likelihood of tensile stress. As a result, proprioceptive feedback does not work, which leads to instability. Surgical reconstruction is indicated to restore proprioception, but the details of recovery after arthroscopic surgery are unknown. The purpose of this study is to investigate whether arthroscopic Bankart repair can improve the position sense of the shoulder. METHODS: We used the isokinetic dynamometer Biodex System 3 (Biodex, Shirley, NY, USA) to investigate preoperative and postoperative joint position sense in 140 shoulders (137 men, 3 women) undergoing arthroscopic Bankart repair for traumatic shoulder joint instability. The control subjects comprised 40 shoulders of healthy volunteers (all men). Active position sense was measured by setting the shoulder external rotation to 75° based on 90° abduction and neutral internal/external rotation position. Reproductive angle inaccuracy (RAI) was measured thrice, and the mean value was calculated. The RAI was measured preoperatively, 6 months and 1 year postoperatively, and at the final observation (range, 16-96 months; mean, 31.5 months). RESULTS: Mean RAI was significantly higher (6.4°) preoperatively in the traumatic shoulder instability group than in the control group (5.0°). Mean postoperative RAI changed to 5.0, 4.9, and 4.7° at 6 months, 1 year, and final observation, respectively (mean, 31.5 months). RAI recovered to the same level as the control group at 6 months after the surgery and was maintained the same level until final observation. CONCLUSION: Position sense was significantly worse in patients with traumatic shoulder joint instability than in healthy volunteers, and a significant improvement in position sense was observed after reconstruction of the anteroinferior glenohumeral ligament complex by arthroscopic Bankart repair. Therefore, arthroscopic Bankart repair is a favorable procedure that can improve the position sense of the shoulder in patients with traumatic shoulder instability.