Underestimated incidence of acute lateral hinge fractures in medial opening wedge high tibial osteotomy: The role of MRI in early detection.

OBJECTIVE

1. Investigate the incidence of lateral-hinge fractures after medial opening wedge high tibial osteotomy using MRI postoperatively alongside radiographs. 2) Determine the number of missed acute lateral-hinge fractures and distinguish them from true delayed fractures 3)Evaluate the complications associated with these fractures.

METHODS

This retrospective study analyzed 250 knees from 227 patients who underwent medial opening-wedge high tibial osteotomy. Radiological evaluation was performed using radiographs, CT scans, and MRI. Patients were categorized into four groups: (1) Acute Lateral-hinge fractures, (2) missed Lateral-hinge fractures, (3) delayed Lateral-hinge fractures and (4) no fractures.

RESULTS

MRI detected lateral hinge fractures (LHF) in 59.6 % of cases, nearly doubling the detection rate of radiographs and CT scans (33.2 %), revealing a significant underestimation of LHF in MOWHTO. Additionally, 73.49 % of presumed delayed fractures were actually missed acute fractures, with a true delayed fracture incidence of only 1.6 %. The fracture groups had a longer healing time and were associated with a loss of correction.

CONCLUSION

The incidence of lateral-hinge fractures after medial opening-wedge high tibial osteotomy is significantly underestimated, with most occurring intra-operatively but often missed on postoperative radiographs and misclassified as delayed fractures. MRI, highly sensitive for early detection and prevention of misclassification, helps optimize rehabilitation strategies and improve patient outcomes.