The impact of residual varus alignment following total knee arthroplasty on patient outcome scores in a constitutional varus population
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© 2018 Elsevier B.V. Background: Following a total knee arthroplasty (TKA), restoration of the mechanical axis of the lower limb to a neutral position of 0° ± 3° is generally considered the standard of care. Little is known, however, regarding the impact of realignment defined according to the patient's physiologic anatomy on clinical outcome scores. Methods: The study included 67 knees with a mean age of 65.9 ± 8.3 years with unilateral osteoarthritis (OA) who underwent a primary unilateral TKA for medial end-stage OA. Patients were categorized based on post-operative limb alignment in one of two ways, either based on alignment relative to their contralateral, physiologic side (physiologic), or alignment relative to a neutral axis (neutral). Knee Society Score (KSS), Western Ontario & McMaster Universities Osteoarthritis Index (WOMAC), and the 12-Item Short Form Survey (SF-12) were compared between the two groups. Results: WOMAC Total and subscale scores improved for both groups between the pre- and post-operative time points. SF-12 scores were comparable post-operatively between the groups. WOMAC and KSS total and subscale scores were slightly greater post-operatively in the group not aligned according to their physiologic anatomy (neutral). However, none of these differences reached a level of significance. Conclusion: Post-operatively, residual varus and neutral limb alignment lead to comparable clinical outcome scores. In a constitutional varus population with medial end-stage OA, aligning the lower limb during a TKA to a neutral position rather than the patient's native anatomy does not negatively impact self-reported patient outcome scores at the one and two-year time points.