CT Detects Hinge Fractures Following Medial Opening Wedge High Tibial Osteotomy: A Systematic Review.

PURPOSE To quantify the increased detection rate of lateral hinge fractures (LHFs) owing to additional computed tomography (CT), determine factors associated with LHF, and compare radiologic and clinical outcomes of LHF following medial opening wedge high tibial osteotomy (MOW-HTO). METHODS The MEDLINE, Embase, Cochrane Library, and Web of Science databases were systematically searched to identify studies reporting the incidence of LHF detected using additional CT, showing radiologic factors, or comparing radiologic and clinical outcomes between LHFs and non-LHFs after MOW-HTO. Subgroup analyses were performed to compare stable and unstable LHF. Two reviewers performed the study screening, risk of bias assessment, and data extraction processes. RESULTS Eleven studies were included in this review. The weighted estimate of apparent incidence of LHF in the pooled studies was 24.8%. The weighted estimate of incidence was increased by 9.9% owing to the use of CT detection, which indicated approximately 40 percent of total diagnosed LHF was missed on plain radiographs or fluoroscopy. The pooled mean opening gap distance was ranged from 11.40 to 12.60mm in the LHF group and ranged from 9.80 to 11.12 in the non-LHF group, and mean difference of opening gap distance was significantly larger in the LHF (95% CI, 0.64-1.84; P < .0001). However, no significant differences in correction loss, bone union duration, and clinical outcomes were observed between the LHF and non-LHF groups. Subgroup analyses showed no significant difference between stable and unstable LHF. CONCLUSION Postoperative CT evaluations increase the detection rate of LHF compared with plain radiography alone. Furthermore, the opening gap distance was larger in the LHF group than in the non-LHF group, suggesting the need for attention when opening a wedge by more than 11.4 mm. However, the consequences of LHFs following MOW-HTO were not major concerns when proper management was provided.