Summary

Combined analysis of radiological and clinical results following DLO showed that large preoperative JLCA was a significant prognostic factor affecting the radiological and clinical outcomes. In cases with JLCA of 4° or more, accuracy of the deformity correction was impaired resulting in less optimal postoperative alignment.

Abstract

Background

Double level osteotomy (DLO) has been indicated for symptomatic severe varus malalignment with the intent of restoring physiologic joint anatomy. However, there is a paucity of information regarding the efficacy of this procedure in attainment of physiologic alignment as well as the relationship between the pre- and postoperative radiological parameters and clinical outcomes.

Purpose

To examine coronal alignment and bony geometry before and after DLO and their effects on the clinical outcome.

Method

The study population was composed of 74 consecutive patients with mean age of 61.1 years (range, 45-76 years) who underwent DLO for severe varus osteoarthritic knees. DLO was adopted as a surgical option when there were combined varus deformities both in the distal femur and the proximal tibia. As for the intended limb alignment, the postoperative hip-knee-ankle angle (HKAA) was set to +1° valgus. The pre- and postoperative radiological and clinical data were retrospectively reviewed for the data acquisition and subjected to the analysis. All the patients could be followed up with for a minimum of 2 years. In the radiological evaluation, mechanical lateral distal femoral angle, mechanical medial proximal tibial angle, joint line convergence angle (JLCA) and HKAA were measured as parameters for the analysis. Outliers were defined as those with deviation of more than 3° from the intended postoperative HKAA (+1° valgus). The relationship between clinical outcomes using the Knee Injury and Osteoarthritis Outcome Score (KOOS) and radiological parameters were statistically assessed.

Results

The radiological evaluation showed that the HKAA was corrected from 13.2° ± 3.0° varus to 0.5° ± 2.8° varus at 2 years after DLO, indicating slight undercorrection on average. Assessment of clinical outcome using the KOOS showed significant improvement from 185 ± 74 before surgery to 388 ± 72 at 2 years. As for the analysis of relationship among various radiological parameters, incidence of the postoperative outlier was significantly higher in patients with preoperative JLCA > 4° than those with JLCA < 4° (39.5% vs. 16.1%, p = 0.03). Correlation analysis between clinical score and postoperative alignment showed positive correlation between KOOS at 2 years and postoperative HKAA (r=0.47, p < 0.01), and the average KOOS at 2 years was significantly lower in the outliers than in the non-outliers (343 ± 82 vs 410 ± 57, p < 0.01).

Conclusions

Combined analysis of radiological and clinical results following DLO showed that large preoperative JLCA was a significant prognostic factor affecting the radiological and clinical outcomes. In cases with JLCA of 4° or more, accuracy of the deformity correction was impaired resulting in less optimal postoperative alignment. Consequently, clinical outcomes were inferior in that group of knees.