Bone graft type is the key determinant of resorption after arthroscopic iliac crest bone grafting: A multicenter study

Purpose Arthroscopic iliac crest bone grafting is an established therapy for anterior shoulder instability with glenoid bone loss. With increasing use of allografts and alternative fixation techniques, their influence on graft resorption remains unclear. This study aimed to identify patient‐, defect‐, graft‐ and surgery‐related factors associated with graft resorption and to characterize longitudinal changes in glenoid morphology following reconstruction. Methods This retrospective multicenter study included patients who underwent arthroscopic iliac crest bone grafting. Preoperative, early postoperative and minimum 1‐year follow‐up computed tomography (CT) scans were analysed. The primary endpoint was graft resorption, defined as the percentage loss of glenoid surface area between postoperative and follow‐up three‐dimensional (3D) CT scans. Associations of patient‐, defect‐, graft‐ and surgery‐related factors, including graft type, fixation technique and graft positioning, with resorption were assessed using separate linear regression models adjusted for follow‐up duration. Secondary endpoints were longitudinal changes in glenoid surface area, preoperative defect size and concavity. Results Thirty‐nine patients (37 men and 2 women; 21 autografts, 18 allografts; mean age 31.8 ± 9.6 years) were included. Mean graft resorption at final follow‐up was 19.9 ± 11.6%. After adjustment for follow‐up duration, allograft use was associated with 7.95 percentage points greater resorption compared with autograft use ( β = 7.95; 95% confidence interval, 0.44–15.46; p = 0.039). Age, sex, prior surgery, preoperative defect, fixation technique and postoperative graft‐positioning parameters were not significantly associated with graft resorption. Significant longitudinal changes were observed for absolute glenoid surface area, relative surface area, glenoid defect size and concavity across the preoperative, postoperative and follow‐up assessments (all p < 0.001). Conclusion Among the factors analysed, only graft type was associated with resorption following arthroscopic iliac crest bone grafting, with greater resorption of allografts than autografts. No association was observed for fixation technique or graft positioning. Level of Evidence Level III.