Free bone grafting improves clinical outcomes in anterior shoulder instability with bone defect: a systematic review and meta-analysis of studies with a minimum of 1-year follow-up

Evidence on the efficacy and safety of the free bone grafting in treating anterior shoulder instability is limited. The purpose of this study was to systematically evaluate the clinical and imaging results of free bone grafting in treating anterior shoulder instability with glenoid bone defect and to explore the incidence of complications in clinically relevant subgroups.This systematic review was conducted per PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-analyses) guidelines. The PubMed, Embase, and Cochrane Library databases were searched up to January 29, 2021, for studies that had reported on free bone grafting in treating anterior shoulder instability with glenoid bone defect with a minimum of 1-year follow-up. Two researchers independently screened studies and extracted data. A random-effects model was used to pool data on clinical function scores, imaging results, and incidence of complications (recurrent instability and non-instability-related complications). Meta-regression analysis was used to evaluate the incidence of complications in different subgroups and investigate the sources of heterogeneity.A total of 29 studies were included in the meta-analysis, comprising 840 patients (845 shoulders) with average ages ranging from 21 to 34.6 years. Compared with preoperatively, free bone grafting increased the postoperative Rowe score, American Shoulder and Elbow Surgeons score, Constant score, Subjective Shoulder Value, and Oxford Shoulder Instability Score by 53.16, 31.80, 20.81, 38.63, and 4.07 points, respectively, and reduced the visual analog scale pain score by 3 points on average. During the postoperative follow-up period, the rates of return to sport and return to preoperative levels were 84.2% and 73.1%, respectively. The imaging results showed that the free bone healing rate was 98.9% and the incidence of osteoarthritis was 10.9%. The incidence rates of recurrent instability and non-instability-related complications were 3.4% and 5.6%, respectively. Meta-regression analysis showed no evidence of effect modification by the year, follow-up time, proportion of male patients, autograft or allograft, and arthroscopy or open surgery on the incidence of complications. Subgroup analysis showed that the incidence rates of recurrent instability for open surgery, arthroscopy, allograft, autograft, Latarjet revision, and non-bone block revision were 4.1%, 2.3%, 1.5%, 4.4%, 10.3%, and 3.5%, respectively.The application of free bone grafting in treating anterior shoulder instability with glenoid bone defect can effectively improve shoulder joint function and is associated with a high return-to-sport rate and a low overall recurrence rate, but there were some differences in the complications of recurrent instability and non-instability-related complications among the subgroups. Given that these results need to be confirmed via head-to-head comparisons, we recommend that future clinical and biomechanical studies focus on comparing and investigating the advantages and disadvantages of different surgical approaches, thus providing a basis for orthopedic surgeons to make reliable choices.