Effect of subcritical glenoid bone loss on activities of daily living in patients with anterior shoulder instability

Background: It has been biomechanically demonstrated that 20% to 25% is a critical glenoid bone loss. Recently, there are several reports describing that a bone loss less than 20% to 25% needed to be treated because patients may have decreased quality of life without recurrent instability events. The purpose of this study was to clarify the presence of subcritical bone loss that would affect postoperative instability or quality of life. Methods: Subjects were 43 patients aged ≤ 40 years with less than 25% glenoid bone loss who had undergone arthroscopic Bankart repair. These patients were assessed at a mean follow-up of 32 months. The Western Ontario Shoulder Instability (WOSI) and Rowe scores were used for the clinical evaluation. Patients were divided in 3 groups based on the percentage of bone loss: group 1: < 8%; group 2: 8% to 17%; and group 3: > 17%. Results: The recurrence rate was 7% (3/43 shoulders). A weak negative correlation was seen between bone loss and sports/recreation/work domain of the WOSI score (r = −0.304, p = 0.0191). The WOSI for group 3 was significantly lower than that for group 1 and 2 (p = 0.0009). The male WOSI scores were significantly lower than the female ones (p = 0.0471). The WOSI scores of the contact athletes were significantly lower than those of non-contact athletes (p = 0.0275). All the patients in Group 3 were males and participated in contact sports. Conclusion: Glenoid bone loss between 17% and 25% is considered to be a “subcritical bone loss” in our series, especially in male patients who are involved in sports or high-level activities. Level of evidence: III, retrospective study.