Joint line convergence angle was an important modifiable factor during OWHTO for the prevention of the recurrence.
Deformities of the hip, knee, and ankle joint all play a role in determining overall lower extremity alignment. It seems likely that some compensatory changes occur at each joint in response to deformity at the others. Knowing the compensatory relationships among of these joints and having more precise information about where they occur would help guide alignment correction in the knee deformity.
Purpose/Hypothesis: The purpose of this study was to evaluate changes in the coronal alignment of the knee and ankle joints after open wedge high tibial osteotomy (OWHTO) and to clarify factors related to the recurrence of the varus deformity by serial analysis. The hypotheses of this study were 1) serial changes in coronal alignment of each joint would be inter-related, and 2) there would be an affecting factor for the recurrence after OWHTO.
From March 2014 to December 2014, a total of 64 consecutive lower limbs (60 patients) that received biplanar OWHTO were enrolled. In the knee joint, preoperative and postoperative weight bearing line (WBL), joint line convergence angle (JLCA), knee joint inclination angle (KIA), and mechanical axis-tibial plateau (MA-TP) angle were evaluated. In the ankle joint, talar inclination (TI) and distal tibia articular angle (DTAA) were evaluated. Standing anterior-posterior (AP) view of the weight bearing whole leg radiographs were taken immediately after surgery, postoperative 3 months, 6 months, and 1 years for the serial assessment. WBL was serially evaluated and was correlated with other factors. To evaluate affecting factors, patients were divided into R (recurrence) and NR (no recurrence) group according to the postoperative one year WBL.
One year after OWHTO, the numbers of Group R and Group NR were 17 (26%) and 47 (74%), respectively. Changes of JLCA, TI, and DTAA which showed statistically significant correlation with WBL were compared between the R and NR groups. Immediate postoperative JLCA was significantly lower in the R group than in the NR group (P<0.05). Difference of the TI of the R and NR group was 5.57 ± 4.16 and 3.77 ± 2.07, respectively. There was a marginal statistical difference between two groups (P = 0.05).
JLCA, TI, and DTAA showed statistically significant correlations at the serial assessment. Among them, JLCA was an important modifiable factor during OWHTO for the prevention of the recurrence because it showed a significant statistical difference between the R and NR groups.
Keywords: High tibial osteotomy, Coronal alignment, Joint line convergence angle, Recurrence