Tibial Components Placed in Constitutional Varus Alignment in Primary Total Knee Arthroplasty: A 5-Year Survivorship...

Placing tibial components in varus alignment has been controversial due to concerns of loosening and subsequent revision. The purpose of this study was to compare 5-year survivorship of tibial components placed in 3° or greater of varus alignment versus neutral mechanical alignment (nMA).

This was a retrospective matched cohort study of 530 patients with 265 patients who underwent primary robotic-assisted total knee arthroplasty (TKA) with tibial components intentionally placed in varus matched to a control group of 265 patients who underwent TKA using manual instrumentation with tibial components placed in nMA. Both cementless and cemented implants were used in both groups. There was no difference between groups with respect to patient sex or age. There were 100 and 87.5% of patients who had a minimum 5-year follow-up in the tibial varus and nMA groups, respectively. Outcomes included survivorship, complications, revisions, and patient-reported outcome measures.

All-cause survivorship at 5 years postoperatively was 98% in the group with constitutional tibial varus and 96% in the nMA group (P = 0.12). There were no cases of aseptic loosening in the group with tibial component varus. There were five patients who required revision in the varus group versus 14 in the nMA group (P = 0.02). There was a significant difference in nonrevision intervention for stiffness between the two groups in favor of the varus group (three versus 14, P = 0.003).

Similar survivorship was demonstrated at a mid-term 5-year follow-up between patients undergoing primary TKA using a functional alternative alignment concept with tibial components intentionally placed in 3° or greater of varus compared to nMA. Tibial components placed in constitutional or anatomic varus, in an attempt to restore the native oblique joint line along with well-balanced gaps, demonstrated 98% survivorship at 5 years.