Description
Abstract
Purpose
Recently, good clinical outcomes have been reported for the Kinematic Alignment Total Knee Arthroplasty (KA-TKA), which aims to restore a patient’s pre-arthritic joint line and ligament balance. However, it has been reported that there is a racial difference in ligament laxity, and the ligament laxity in Japanese populations remains unclear. So we investigated native knee laxity in the healthy Japanese population and analyzed the correlation between ligament laxity and lower limb alignment.
Methods
Healthy volunteers under 50 years of age, without a history of past trauma or inflammatory disease, were recruited for the study. A total of 31 participants, corresponding to 60 knees, were included in this study. The mechanical Hip Knee Ankle angle (mHKA) was assessed using long-leg radiographs. Additionally, we evaluated the varus/valgus laxity of the knee, which was calculated as the difference between lateral/medial laxity observed in stress radiographs and the laxity in neutral radiographs without applied stress. In the statistical analysis, a paired t-test was used to assess the differences in the degree of varus/valgus laxity. Additionally, the Pearson correlation coefficient was used to examine the relationship between lower limb alignment and ligament balance. p < 0.05 was considered statistically significant.
Results
Lower limb alignment was -2.0° ± 2.5°and the stress radiograph revealed varus laxity of 3.7° ± 1.3° and valgus laxity of 3.0° ± 1.1°. Statistical analysis revealed that mHKA was not significantly correlated with either the degree of varus or valgus laxity of the knee. On the other hand, varus laxity was significantly greater than valgus laxity (p < 0.001).
Conclusion
Our results revealed that the lower limb alignment of Japanese healthy volunteers was more varus than that of Caucasians, but lower limb alignment was not correlated with knee laxity. Varus laxity was greater than valgus laxity and the degree was 0.66°. Previous reports on Caucasians have also indicated a greater degree of varus laxity ranging from about 0.5° to 1.1°, which aligns closely with the results of the present study. These results show that racial differences are not significant with respect to ligament balance.
