Effect of Fibular Height and Lateral Tibial Condylar Geometry on Lateral Cortical Hinge Fracture in Open Wedge High Tibial Osteotomy.

PURPOSE: To evaluate whether the fibular position and lateral proximal tibial geometry affect the osteotomy configuration and lateral hinge fracture (LHF) during open wedge high tibial osteotomy (OWHTO).

METHODS: From March 2014 to January 2016, patients who underwent OWHTO for isolated medial compartment osteoarthritis of the knee were retrospectively reviewed. To identify whether the fibular position and lateral proximal tibial geometry affect the osteotomy configuration, the fibular height, fibular anteroposterior position, lateral tibial condylar width, and lateral tibial condylar slope were evaluated on plain radiograph or computed tomography (CT). Thereafter, the correlation of these parameters with the thickness of the proximal fragment around the osteotomy end and LHFs was determined.

RESULTS: A total of 123 OWHTOs including 30 LHFs (24.3%) were evaluated. High fibular head and small tibial condylar width and slope were related to thin thickness of the proximal tibial fragment, particularly on the posterior side (fibular height, P = .005; condylar width, P = .002; condylar slope, P = .01). The fibular height was shorter in the LHF group than in the non-LHF group on both plain radiography and CT (fibular height [plain radiography], 18.3 ± 1.6 vs 20.2 ± 2.1 mm; P < .001; fibular height [CT], 17.4 ± 1.1 vs 19.6 ± 2.0 mm; P < .001). The lateral tibial condylar width and slope were also smaller in the LHF group compared with the non-LHF group (tibial condylar width, 21.2 ± 4.9 vs 23.4 ± 4.5 mm; P = .023; tibial condylar slope, 37.7 ± 6.6 vs 41.3 ± 7.6 mm; P = .027).

CONCLUSIONS: The fibular position and lateral proximal tibial geometry affect the osteotomy configuration and LHFs. A highly positioned fibula was related to a small lateral tibial condyle, which induced a thin proximal fragment. This finding was related to a higher risk of LHFs. Therefore, understanding the fibular height and lateral proximal tibial geometry may be helpful for the prediction of the osteotomy configuration and development of LHFs.

LEVEL OF EVIDENCE: Level III, case-control study.