Alterations in Ankle Biomechanics and Alignment Following Unilateral Total Knee Arthroplasty for Valgus Deformity: An Eastern Indian Cohort Study

Dr. Bighnesh Dash, Dr. Aurobinda Das

Abstract: Background: While Total Knee Arthroplasty (TKA) is highly effective in restoring knee kinematics, its cascading biomechanical effects on the bilateral ankle joints- particularly in the context of valgus knee deformities, which often present late and with significant severity in the Eastern Indian demographic-remain inadequately defined. This study aimed to quantify the impact of unilateral TKA on ipsilateral and contralateral ankle tilt, lower extremity alignment, and compensatory biomechanics in valgus osteoarthritis. Methods: A retrospective cohort study was conducted at a tertiary medical college, analyzing 31 consecutive patients who underwent unilateral TKA for end-stage knee osteoarthritis complicated by mild-to-moderate valgus deformity between January 2023 and January 2025. Comprehensive pre- and postoperative standing full-length lower limb radiographs were evaluated. Key radiographic parameters included the hip-knee-ankle angle (HKA), weight-bearing line ratio (WBLR), knee joint line convergence angle (KJLCA), knee joint line obliquity (KJLO), tibial anterior surface angle (TAS), tibial plafond inclination (TPI), talar inclination (TI), and tibiotalar tilt (TT). To assess the impact of surgical correction magnitude, the 31 participants were stratified into three cohorts based on the degree of alignment correction: Cohort I (0°-5°, n=9), Cohort II (5°-10°, n=14), and Cohort III (10°-15°, n=8). Additionally, patients were sub-classified based on the preoperative alignment of the unoperated contralateral knee into varus (n=12) and valgus (n=19) groups. Results: Radiographic analysis demonstrated that mechanical axis restoration (HKA change) precipitated simultaneous, statistically significant alterations in both the TAS and TT. The absolute values for postoperative TAS and TT exhibited significant increases compared to their preoperative baselines (p<0.05). This indicates that realignment of the lower limb mechanical axis during TKA fundamentally modifies the inclination of the talar articular surface. Furthermore, inter-group analysis revealed significant variances in the delta values of TPI (?TPI) and TI (?TI) across the three correction cohorts (p<0.05). Severe preoperative knee valgus correlated with a steeper baseline angulation between the distal tibial articular surface and the horizontal plane. Consequently, radical correction of severe deformities resulted in a heightened postoperative TI, producing a more obliquely oriented talar articular surface. Conversely, alterations in the ipsilateral limb's HKA exhibited no statistically significant correlation with the alignment parameters of the contralateral ankle joint. Conclusion: Unilateral TKA induces immediate, concurrent morphological shifts in the ipsilateral ankle?s inclination angle. In the Eastern Indian demographic, where severe valgus deformities are common, orthopaedic surgeons must exercise caution: aggressively restoring a neutral mechanical axis in severe valgus cases may lead to excessive talar inclination. Purposefully retaining a mild residual valgus deformity should be considered as a strategic compromise to preserve ankle biomechanics and prevent postoperative distal arthropathy.

Keywords: Knee valgus deformity, Ankle alignment, Total knee arthroplasty, Lower limb alignment, Knee alignment

How to Cite?: Dr. Bighnesh Dash, Dr. Aurobinda Das, "Alterations in Ankle Biomechanics and Alignment Following Unilateral Total Knee Arthroplasty for Valgus Deformity: An Eastern Indian Cohort Study", Volume 15 Issue 2, February 2026, International Journal of Science and Research (IJSR), Pages: 1568-1577, https://www.ijsr.net/getabstract.php?paperid=SR26225181044, DOI: https://dx.dx.doi.org/10.21275/SR26225181044

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