Slight under-correction following total knee arthroplasty for a valgus knee results in similar clinical outcomes
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Restoration of correct coronal alignment is one of the main goals of total knee arthroplasty (TKA). Traditionally, TKA has been considered successful when a neutral mechanical hip–knee–ankle (HKA) axis within 3° is achieved. Recent studies have reported no differences or improved clinical outcomes following a slight under-correction of the HKA axis for a varus knee. However, the influence of under-correction of a valgus knee has not been reported. This study investigated the influence of post-operative HKA alignment in TKA patients with valgus deformity on clinical outcomes.
Ninety-three knees (93 patients) with pre-operative valgus alignment were evaluated with a mean follow-up period of 60 months. All patients were classified into three groups based on post-operative HKA alignment: neutral (0 ± 3°), mild valgus (3°–6°), and severe valgus (> 6°). These groups were compared using the Western Ontario and McMaster Universities osteoarthritis (WOMAC) index, the Knee Society (KS) knee score, KS function score, α-angle, β-angle, patella tilt angle, and the congruence angle.
Sixty-nine knees were included in the neutral group, seventeen knees in the mild valgus group, and seven knees in the severe valgus group. In all cases, post-operative clinical and functional scores significantly improved compared to pre-operative scores. There were no differences between the three groups in post-operative clinical and functional scores. More post-operative patellar tilt angle outliers (> 10°) and congruence angle outliers (> 16°) were apparent in the severe valgus group (patellar tilt angle, 13 vs. 17 vs. 57.1%, p = 0.022; congruence angle, 32 vs. 47 vs. 71%, p = 0.035).
Slight under-correction following TKA for a valgus knee resulted in similar clinical outcomes. A residual valgus angle of more than 6° can induce patellar maltracking.
Level of evidence
III, Retrospective comparative study.
KeywordsAlignment Neutral alignment Total knee replacement Knee valgus Patellar maltracking
There is no funding source.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
This article does not contain any studies with human participants or animals performed by any of the authors. The protocol used to evaluate radiographic findings and intraoperative navigation data was approved by our institution’s investigational review board (SMC2017-06-008).
Informed consent was obtained from all individual participants included in the study.
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