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What is the relationship between the "Fujisawa point" and postoperative knee valgus angle? A theoretical,
Yingchao Yin1, Shilun Li1, Ruipeng Zhang1
1Department of Orthopaedic Surgery, The Third Hospital of Hebei Medical University, No. 139 Ziqiang Road, Qiaoxi District, Shijiazhuang 050051, Hebei Province, China.
Background:
The purpose of this study was to determine the relationship between the Fujisawa point and postoperative knee valgus angle and the anatomical factors influencing this relationship.
Methods:
An experimental study was conducted including 116 patients with medial compartment knee osteoarthritis undergoing treatment with open-wedge high tibial osteotomy (OWHTO). Each patient received simulated HTO through the Fujisawa point in the picture archiving and communication system (PACS). The preoperative hip-knee-ankle (HKA) angle and lower extremity anatomical parameters were recorded before the computerized HTO simulation. The postoperative knee valgus angle was measured after this procedure. A second simulation HTO was performed to adjust the mechanical axis to the optimal valgus angle (4.5°) and calculate the percentage of the tibial plateau width where the Mikulicz line crossed the knee. The Spearman correlation test and multivariate regression were used for analysis.
Results:
The median preoperative HKA varus angle of this study cohort was 174.1° (170.8, 176.2°). The median knee valgus angle after simulated osteotomy through the Fujisawa point was 2.4° (2.1, 2.7°). The valgus angle was positively correlated with the tibial plateau width (r = 0.23, p = .013) and preoperative HKA angle (r = 0.32, p < .001). Multivariate regression analysis showed that the preoperative HKA angle was a significant contributor to the postoperative valgus angle. When conducting the osteotomy with the optimal valgus angle (4.5°), the percentage of the Mikulicz line passing through the tibial plateau was 71.93% (67-78%).
Conclusions:
The preoperative HKA angle affects the postoperative valgus angle after HTO. If the optimal valgus angle of 4.5° is desired, a more lateral position of the Fujisawa point should be targeted during OWHTO, which accounts for approximately 71.9% of the tibial plateau.
