Background: Accurate alignment is a basic principle of TKA surgery, but achieving alignment within this target may not translate into superior outcomes after surgery.
Purpose: To assess if neutral TKA mechanical alignment was associated with superior knee outcomes and to examine the effect of various aspects of pre-operative and post-operative alignment on knee function.
Methods: Analysis of a database of 444 TKA patients between June 2009 and October 2016. Knee outcomes (WOMAC, AKSS and knee range of motion) were collected before surgery and during follow-up at a minimum of six months.
Results: Analysis included 444 TKA patients (62% female, mean age 66 years, mean follow-up 23 months). Deformity varied from 21° varus (mean = 7.9, SD = 2.8) to 17° valgus deformity (mean = 7.7, SD = 2.8). Pre-operatively, 101 (23%) knees were in native neutral mechanical alignment, while 278 (63%) were in varus and 65 (15%) were in valgus. Post-operatively, a group of 365 (82%) TKA were found to be in neutral mechanical alignment and a group of 79 (18%) TKA were noted to be 'Outliers' (17 [4%] TKA > 3° varus and 62 [14%] TKA > 3° valgus alignment). Restoration of the target of alignment of 0 ± 3° or 0 ± 1°, did not have better functional outcomes scores, range of motion or prosthesis longevity than those in the outlier range.
Conclusion: Neutral TKA alignment did not appear to be a significant contributing factor to the improvement in knee function in short-medium term follow-up.
Keywords: Alignment; Function; Mechanical axis; Patient satisfaction; Prognosis; Total knee arthroplasty.
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