Summary

The lateral closed wedge HTO might be more protective for the patellofemoral joint than the medial open wedge HTO because the former led to more anterior, medial, and proximal displacements combined with more internal rotations of the distal tibial fragment including the tibial tubercle, whereas the latter did posterior and distal displacement.

Abstract

Purpose

There has been little in-vivo clinical information about the effect on the three-dimensional tibiofemoral relationship after high tibial osteotomy (HTO). This study aimed to compare the postoperative three-dimensional change of the tibiofemoral relationship between medial open wedge (MOW) HTO and lateral closed wedge (LCW) HTO.

Methods

From January 2019 to July 2022, 17 patients (MOWHTO for 8 patients and LCWHTO for 9 patients), who were relatively active and underwent HTO for medial early knee osteoarthritis with varus deformity and underwent three-dimensional computed tomography (CT) scans preoperatively and 1 year postoperatively, were enrolled. No patients had a concomitant cruciate ligamentous injury. Age and body mass index were comparable (MOWHTO; 57±10 years and 25±2, LCWHTO; 57±8 years and 27±4), whereas there was a significant difference in terms of sex (MOWHTO; male/female: 3/5, LCWHTO; male/female: 8/1). MOWHTO was performed for the patients with a coronal correction angle within 10°, while LCWHTO was performed with the correction angle more than 10° and/or a combined apparent degeneration in the patellofemoral joint. Postoperatively, range-of-motion exercise was started at 1 week and partial weightbearing was started at 2–3 weeks followed by full weightbearing at 4–5 weeks in both groups. During CT examinations, the patients were laid in a spine position and asked to relax their muscular contraction with their knees extended. Then, three-dimensional models of the femur and tibia and coordinate systems were created, while postoperatively the proximal and distal tibial models were respectively constructed. Using a surface registration technique, the three-dimensional change of femur–proximal tibia and proximal tibia–distal tibia through HTO was calculated and compared between the two surgical techniques.

Results

After MOWHTO, the proximal tibial position relative to the femur showed non-significant anterior (0.4±1.4mm), medial (0.5±0.9mm), and distal (0.1±0.6mm) displacement as well as non-significant internal (1.8°±1.4°) and varus (1.0°±1.1°) rotation. The distal tibial position relative to the proximal tibia showed significant posterior (1.9±1.2mm, p=0.02) and distal (3.4±1.5mm, p<0.01) with non-significant lateral (0.5±1.3mm) displacement as well as non-significant external (0.7°±2.5°) and significant valgus (7.9°±2.0°, p<0.01) rotation. After LCWHTO, the proximal tibial position relative to the femur showed non-significant posterior (0.9±1.6mm), medial (0.5±0.9mm), and proximal (0.5±0.7mm) displacement as well as significant external (1.4°±1.3°, p=0.03) and non-significant varus (0.0°±1.2°) rotation. The distal tibial position relative to the proximal tibia showed significant anterior (2.5±1.3mm, p<0.01), medial (5.7±2.6mm, p<0.01), and proximal (5.0±2.1mm, p<0.01) displacement as well as significant internal (4.6°±2.7°, p<0.01) and valgus (11.7°±2.3°, p<0.01) rotation. In comparison of the change of the proximal tibia relative to the femur between the two procedures, no significances were detected except for the internal–external rotation (p<0.01). In comparison of the postoperative of the distal tibial position relative to the proximal tibia, significant differences were observed in all the translation/rotational parameters (p<0.01).

Conclusion

LCWHTO led to more anterior, medial, and proximal displacements combined with more internal and valgus rotations of the distal tibial fragment including the tibial tubercle, whereas MOWHTO did posterior and distal displacement. This finding highlighted that LCWHTO might be advantageous for patellofemoral joint protection.