Kinematic Alignment-TKA using Medial Pivot implants appropriate surgical approach for valgus alignment knees: study

Mechanical alignment total knee arthroplasty (TKA) in valgus knees requires soft tissue releases and complex techniques that are unnecessary with kinematic alignment (KA). Few studies have evaluated the outcomes of KA in valgus knees, and fewer have studied KA with medial-pivot (MP) implants. The study by Emma N. Horton et al compared the clinical outcomes of KA-TKA with MP implants (KA/MP-TKA) in patients with preoperative varus versus valgus alignment.

A prospective database was queried to identify patients who underwent primary KA-TKA with MP implants. Patients were included if they had a preoperative hip-knee-ankle angle less than 177 (varus, n = 302) or more than183 (valgus, n = 51). A total of 353 consecutive patients were identified. The Forgotten Joint Score (FJS), Knee Injury and Osteoarthritis Outcome Score (KOOS-JR), Knee Society Score (KSS), and range of motion were collected preoperatively and at 6-week, 6-month, and 1-year visits.

The key findings of the study were:

• Patients with preoperative valgus alignment had worse KSS Function and KOOS-JR scores preoperatively (p = 0.04 and p = 0.02, respectively); all other baseline outcomes were comparable.

• Postoperatively, the valgus group demonstrated better KOOS-JR at 6 weeks (p = 0.004), KSS Pain-Motion at 6 months (p = 0.02), and FJS at 1 year (p = 0.03).

• The varus group showed better KSS Function at all postoperative visits (p < 0.02).

• There were no statistically significant differences in flexion or extension between the groups.

The authors concluded – “Patients with preoperative valgus knee alignment who undergo KA-TKA with true “ball-in-socket” MP implants achieve postoperative outcomes that are clinically equivalent or superior to those of patients with varus alignment. In this study, the valgus group demonstrated better outcome scores and flexion than those reported in the literature. These results support KA-TKA using MP implants as an appropriate surgical approach for preoperative valgus alignment, with added benefits of reduced invasiveness and complexity. However, the widespread adoption of this approach should await long term data to verify that there is no increased rate of aseptic loosening.”

Further reading:

Medial-Pivot Total Knee Arthroplasty with Kinematic Alignment Produces Similar Clinical Outcomes in Valgus and Varus Deformities

Emma N. Horton et al

JBJS Open Access 2026:25.00308.

http://dx.doi.org/10.2106/JBJS.OA.25.00308