Influence of Bony Defects on Preoperative Shoulder Function in Recurrent Anteroinferior Shoulder Instability

Abstract

Background: Recurrent anteroinferior shoulder dislocations are often associated with bony glenoid and humeral defects. The influence of those bony lesions on the postoperative outcomes after arthroscopic shoulder stabilization procedures has been the subject of many studies. Little is known about the influence of those lesions on preoperative function. Purpose: To evaluate the influence of glenoid and humeral bony defects on preoperative shoulder function in recurrent anteroinferior shoulder instability. Study Design: Cross-sectional study; Level of evidence, 3. Methods: Included in the study were 90 patients (70 men, 20 women; mean age, 27.1 years; 24 patients with prior failed stabilization) with posttraumatic recurrent anteroinferior shoulder instability who underwent preoperative computed tomography (CT) of both shoulders. The glenoid index was used to measure glenoid defect on a 3-dimensional CT. Humeral head defect was measured on a 2-dimensional CT with evaluation of the Hill-Sachs quotient, product, sum, and difference. Preoperative evaluation also included the Rowe score, Constant score, Walch-Duplay score, Melbourne Instability Shoulder Score (MISS), Western Ontario Shoulder Instability Index (WOSI), and Subjective Shoulder Value (SSV). Results: There was a weak but significant correlation of the Hill-Sachs quotient and the glenoid index with the Rowe score (P = .03, r = −0.22 and P = .03, r = 0.23, respectively). Furthermore, the Hill-Sachs product significantly correlated with the WOSI (P = .02); in particular, the physical symptoms subscore showed a significant correlation (P = .04). The glenoid index showed a significant correlation with the SSV (P < .01). No significant correlation was found between the Walch-Duplay score, Constant score, or MISS and bony defects. Conclusion: The results of this study show that objective and subjective scoring systems correlate significantly with the clinical condition of patients with recurrent shoulder instability and associated bony defects. It is recommended that clinicians use the Rowe score, WOSI, and SSV for the clinical evaluation of patients with recurrent anteroinferior shoulder instability and associated bony defects. These evaluation systems may provide an early clinical indication of bony defects. Furthermore, very poor results on these evaluations could underline the necessity of a CT scan for the diagnosis of bony defects in recurrent shoulder instability and might be helpful for decision making concerning the indication of a CT.