Clinical Outcomes of Glenoid Fractures Following Manipulation Under Anesthesia for Frozen Shoulder

Background Frozen shoulder (FS) is commonly treated conservatively, but manipulation under anesthesia (MUA) is used for refractory cases. Although MUA provides rapid improvement in range of motion (ROM) and pain, it carries a risk of iatrogenic injuries, including glenoid fractures. This study investigated the incidence and clinical impact of glenoid fractures following MUA. Methods We retrospectively reviewed 301 patients with primary FS in the frozen stage who underwent MUA between 2013 and 2023. Glenoid fractures were assessed using radiographs, ultrasonography, and Garth view, with computed tomography when necessary. Patients were divided into fracture and non-fracture groups. Outcomes included symptom duration, ROM, pain scores (Numeric Rating Scale [NRS]), and Japanese Orthopaedic Association (JOA) score, assessed preoperatively and at 1, 3, and 6 months postoperatively. Results The radiographically detected incidence of glenoid fracture was 1.7% (5 patients), all Ideberg type Ia without instability. Symptom duration before MUA was significantly longer in the fracture group (12 vs. 6 months, p=0.0199). No significant differences were observed in postoperative ROM, NRS, or JOA scores between groups. Conclusions Glenoid fractures after MUA are rare and small. No adverse impact on short-term outcomes was detected in this cohort, although the small number of fracture cases limits the power of this analysis. MUA remains a safe and effective treatment option for refractory FS.