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.
- 1.Ritter MA, Faris PM, Keating EM, Meding JB (1994) Postoperative alignment of total knee replacement. Its effect on survival. Clin Orthop Relat Res 299:153–156Google Scholar
- 6.Slevin O, Hirschmann A, Schiapparelli FF, Amsler F, Huegli RW, Hirschmann MT (2017) Neutral alignment leads to higher knee society scores after total knee arthroplasty in preoperatively non-varus patients: a prospective clinical study using 3D-CT. Knee Surg Sports Traumatol Arthrosc. https://doi.org/10.1007/s00167-017-4744-y CrossRefPubMedGoogle Scholar
- 16.Boettner F, Renner L, Arana Narbarte D, Egidy C, Faschingbauer M (2016) Total knee arthroplasty for valgus osteoarthritis: the results of a standardized soft-tissue release technique. Knee Surg Sports Traumatol Arthrosc 24(8):2525–2531. https://doi.org/10.1007/s00167-016-4054-9 CrossRefPubMedGoogle Scholar
- 18.Bellamy N, Buchanan WW, Goldsmith CH, Campbell J, Stitt LW (1988) Validation study of WOMAC: a health status instrument for measuring clinically important patient relevant outcomes to antirheumatic drug therapy in patients with osteoarthritis of the hip or knee. J Rheumatol 15(12):1833–1840PubMedGoogle Scholar
- 19.Insall JN, Dorr LD, Scott RD, Scott WN (1989) Rationale of the Knee Society clinical rating system. Clin Orthop Relat Res (248):13–14Google Scholar
- 25.Moon YW, Seo JG, Yang JH, Shon MS (2008) Analysis of the patellofemoral congruence angle according to the rotational alignment of the femoral component in navigation-guided TKA. Orthopedics 31(10 Suppl 1):62–67Google Scholar
- 26.Lee WC, Kwan YH, Chong HC, Yeo SJ (2017) The minimal clinically important difference for knee society clinical rating system after total knee arthroplasty for primary osteoarthritis. Knee Surg Sports Traumatol Arthrosc 25(11):3354–3359. https://doi.org/10.1007/s00167-016-4208-9 CrossRefPubMedGoogle Scholar
- 37.Slevin O, Schmid FA, Schiapparelli FF, Rasch H, Amsler F, Hirschmann MT (2017) Coronal femoral TKA position significantly influences in vivo patellar loading in unresurfaced patellae after primary total knee arthroplasty. Knee Surg Sports Traumatol Arthrosc. https://doi.org/10.1007/s00167-017-4627-2 CrossRefPubMedGoogle Scholar