Preservation of preoperative CPAK is not associated with improved clinical outcomes one-year after functionally aligned robot-assisted TKA.

Abstract

To determine if maintaining the preoperative CPAK class influences on clinical outcomes when performing a functional aligned robotic assisted TKA (RATKA). This prospective cohort study compared patients who maintained their preoperative CPAK classification following functionally aligned RATKA with those who did not. Clinical outcomes were assed at 6 and 12 months postoperatively. Collected data included demographics variables, pain (VAS), range of motion (ROM), KOOS scores and radiographic parameters (HKA, MPTA, LDFA). JLO and aHKA values were calculated to determine CPAK classification. Fifty-five patients were included. The preoperative CPAK phenotype was preserved in 34.6 % of cases, the aHKA group in 55.6 % and the JLO group in 52.7 %. JLO preservation was significantly more frequent in distal-apex knees (90 %). Preservation of the preoperative CPAK phenotype, aHKA group or JLO group had no significant effect on knee ROM, pain or functional outcomes at 6 or 12 months postoperatively. Changes in CPAK classification, aHKA or JLO during RATKA with functional alignment do not impact clinical outcomes at 6 or 12 months. Implant positioning should aim for a stable, well-balanced knee within safe positioning boundaries, rather than exact CPAK restoration. III.