The effect of frontal plane osteotomy angle on lateral cortex fracture in medial open wedge high tibial osteotomy procedure

Background

Precise high tibial osteotomy is crucial, especially for middle-aged individuals with medial compartment arthritis, aiming to prevent complications like lateral cortex fractures. This study explores how frontal plane osteotomy inclination impacts lateral cortex fractures during medial open-wedge high tibial osteotomy.

Methods

Using finite element analysis, tibia models underwent osteotomies at angles of 10°, 13°, 16°, 19°, and 22°, forming five models. Forces from 5 N to 75 N were applied incrementally, recording bone stresses (MPa) at the lateral hinge, angle changes (°) along the osteotomy line, and gap distances (mm).

Results

Models with higher frontal inclination showed increased gap distances under identical forces. For instance, at 5 N force, the 10° inclination model displayed a correction angle of 0.28° and a 1.43 mm gap, while the 22° model had a correction angle of 0.35° and a 1.37 mm gap. Under 75 N force, the 10° model had a correction angle of 10.81° and a 14.02 mm gap, while the 22° model had a correction angle of 16.86° and a 19.31 mm gap.

Conclusion

The osteotomy starting point’s distance from the joint doesn’t significantly impact final stress on the lateral cortex when the same gap distance is achieved. However, in cases requiring a higher degree of correction, we can say that the surgeon can achieve the result with less resistance by keeping the osteotomy starting point more distal to the joint line.