Does Total Knee Arthroplasty Affect Ankle and Hindfoot Alignment? A Prospective Study on Functional and Radiological...

To maintain a plantigrade foot, knee deformity prompts compensatory hindfoot deformity. TKA realigns the knee correcting hip-knee angle (HKA) However, the consequential impact of severe varus on ankle and foot has been inadequately investigated in contemporary literature.

The study consisted of 66 patients (87 knees) who underwent TKA. The radiological parameters assessed were hip-knee angle (HKA), tibial plafond inclination angle (TPIA), tibio-talar tilt angle (TTTA) and talar inclination angle (TIA). Functional assessment was done with AOFAS score pre-operatively and at 2-year follow-up. The paired t test and Pearson's correlation tests were used for statistical analysis.

HFA, TPI, TTT, and TIA post-TKA showed statistically significant correction (p < 0.001 for all parameters). On correlating HKA with hindfoot alignment, for physiological HFA ≤ 6 degrees, the mean correction in HFA was 2.55 degrees (r = 0.668, p < 0.001) and for abnormal HFA > 6, the mean correction in HFA was 6.47 degrees (r = 0.355, p = 0.029). On correlating correction of ankle alignment with correction in HKA, correction in TPI (r = 0.04, p = 0.713), TTT (r = -0.017, p = 0.874), TIA (r = 0.158, p = 0.144) was not statistically significant. Significant improvement in AOFAS was seen post-TKA with a mean increase from 72.0 to 88.9 (p < 0.001).

TKA improves ankle and hindfoot alignment both radiologically and functionally. However, any persistent malalignment in the ankle and hindfoot can lead to patient dissatisfaction.