Residual varus alignment does not compromise results of TKAs in patients with preoperative varus

Abstract

Background: Postoperative varus alignment has been associated with lower IKS scores and increased failure rates. Appropriate positioning of TKA components therefore is a key concern of surgeons. However, obtaining neutral alignment can be challenging in patients with substantial preoperative varus deformity and it is unclear whether residual deformity influences revision rates.

Questions/purposes: We asked: (1) in patients with preoperative varus deformities, does residual postoperative varus limb alignment lead to increased revision rates or lower IKS scores compared with correction to neutral alignment, (2) does placing the tibial component in varus alignment lead to increased revision rates and lower IKS scores, (3) does femoral component alignment affect revision rates and IKS scores, and (4) do these findings change in patients with at least 10° varus alignment preoperatively?

Patients and methods: From a prospective database, we identified 553 patients undergoing TKAs for varus osteoarthritis. Patients were divided into those with residual postoperative varus and those with neutral postoperative alignment. Revision rates and International Knee Society (IKS) scores were compared between the two groups and assessed based on postoperative component alignment. Survival analysis was conducted with revision as the endpoint. The analysis was repeated in a subgroup of patients with at least 10° preoperative varus. Minimum followup was 2 years (median, 4.7 years; range, 2-19.8 years).

Results: The two groups had similar survival rates to 10 years and similar IKS scores. Varus tibial component alignment and valgus femoral component alignment were associated with lower mean scores. Revision rates and scores were similar in a subgroup of patients with substantial preoperative varus.

Conclusions: Our data suggest residual postoperative varus deformity after TKA does not increase survival rates at medium-term in patients with preoperative varus deformities, providing tibial component varus is avoided. Tibial component varus negatively influences IKS score.

Level of evidence: Level III, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

Figures

Fig. 1

A Kaplan-Meier survival curve with revision as an endpoint shows the influence of postoperative limb alignment on implant survival rates in patients with varus osteoarthritis preoperatively. We found no difference (p = 0.8) between patients with residual varus deformity and patients with neutral postoperative alignment.

Fig. 2

A graph shows the influence of postoperative TMA on IKS score in patients with varus osteoarthritis preoperatively. Patients with varus alignment of the tibial component had lower (p = 0.002) mean scores compared with those with neutral alignment. We observed no differences in patients with valgus alignment and either varus or neutral component alignment. Values are shown as mean with SD (error bar).

Fig. 3

A graph shows the influence of postoperative FMA on IKS score in patients with varus osteoarthritis preoperatively. We observed lower mean scores in patients with valgus alignment of the femoral component compared with those with varus (p 

Fig. 4

A Kaplan-Meier survival curve shows the influence of postoperative limb alignment on implant survival rates in patients with varus osteoarthritis and a preoperative deformity of at least 10°. We found no differences (p = 0.6) in patients with residual varus deformity and patients with neutral postoperative alignment.

Fig. 5

A graph shows the influence of postoperative FMA on IKS score in patients with substantial varus osteoarthritis (at least 10° varus) preoperatively. We found lower mean scores in patients with valgus alignment of the femoral component compared with those with varus (p