Total knee arthroplasty in patients with substantial deformities using primary knee components.

PURPOSE: Although advocated for severe varus and valgus deformities, constrained implant designs are associated with a number of disadvantages in total knee arthroplasty (TKA). Combining a minimally invasive surgical approach with an interchangeable posterior stabilized (PS) implant design may allow adequate soft tissue balancing with a minimal amount of constraint and without residual instability.
METHODS: Retrospectively 51 patients operated with the minimally invasive far medial subvastus approach for severe varus or valgus deformity, who underwent primary TKA with a fully interchangeable PS implant (Vanguard, Biomet Inc., Warsaw IN, USA) between 2009 and 2013 were examined. Soft tissue releases was performed using a piecrust needling technique. Preoperative alignment and surgical parameters were collected for all patients. All patients underwent preoperative and follow-up radiographic assessment and completed a battery of clinical assessments.
RESULTS: All procedures were performed successfully, with alignment improving from a preoperative mean (SD) varus deformity of 165° (3°) and a mean (SD) valgus deformity of 196° (4.5°) to an overall mean (SD) postoperative mechanical alignment of 179.5° (3.0°). Nine patients had postoperative varus, while three patients had a postoperative valgus deviation from neutral alignment >3°. The mean change in joint line position in extension was -0.0 ± 0.6 mm. Clinical scores at final follow-up were excellent for both groups.
CONCLUSIONS: Good TKA outcomes can be achieved in patients with substantial varus or valgus deformities using a combination of a minimally invasive far medial subvastus approach, interchangeable PS implants and soft tissue releases with a piecrust needling technique. LEVEL OF EVIDENCE: III.