Summary

Valgus deformity was not associated with inferior patient reported outcomes or lower rates of satisfaction, compared to varus knees at 1 year after arthroplasty.

Abstract

Introduction

Coronal deformities are commonly seen in subjects prior to total knee arthroplasty (TKA). A valgus alignment may represent a greater technical challenge for the surgeon. It has recently been reported that a valgus deformity is associated with a two-fold risk of failure at a median of 3.3 years with an incidence of 3.3%, compared to 1.4% in varus aligned TKA. The effect of coronal alignment on patient reported outcomes (PROMS) after arthroplasty has received relatively little attention and its effect on satisfaction with TKA has not been reported.

Methods

Between 2019 and 2021 597 consecutive patients underwent primary TKA for osteoarthritis and consented to participation in a prospective database under the care of the 3 investigating surgeons, and completed baseline PROMS. Operative data was collected prospectively and included the preoperative long leg coronal alignment measured on computerised tomography (CT) or EOS scan. PROMS at 12 months included Oxford Knee Score, KOOS JR, EQ5D and patient satisfaction. Outcomes were compared between varus and valgus knees, and by the degree of alignment as follows: valgus 10 degrees or more, valgus 0-9 degrees, varus 0-9 degrees and varus 10 degrees or more.

Results

597 subjects formed the study group and 557 completed PROMS at 12 months after TKA (84%), and were included in the analysis. There were 300 males and 308 right knees. The mean age was 68 years (range 33-92). The preoperative alignment was in varus in 426 (77%), neutral in 18 (3%) and valgus in 113 (20%). The valgus group had significantly more females (63% vs 42%, p=0.001), an older mean age (70 vs 68 p=0.001), compared to the varus group. There was no difference between the valgus and varus group for baseline BMI, Oxford Knee Score or KOOS JR score.
At 1 year after TKA 90% of valgus knees and 90% of varus knees reporting that they were satisfied or very satisfied with surgery (p=0.877), and 94% of varus knee and 95% of valgus knees reported there knee problems were better than before surgery (p=0.808). At 1 year the mean KOOS Jnr score was 79 in both groups (p=0.883), and the mean Oxford Knee Score was 41 in the varus group and 40 in the valgus group (p=0.415).
The varus outliers (10 degrees or more) had greater mean improvement (p=0.005) and a higher mean 1 year Oxford score than the other groups (p=0.032). A significantly higher rate of satisfaction with surgery (p=0.003) and proportion reporting they would undergo the same surgery again (p=0.029) was observed in the both the valgus and varus outliers (10 degrees or more) (97-100%) compared to those within 10 degrees alignment (88-90%).

Conclusions

Preoperative valgus deformity was observed in 20%, and predominantly affects females. Valgus deformity was not associated with inferior patient reported outcomes or lower rates of satisfaction, compared to varus knees at 1 year after arthroplasty. Those with preoperative coronal alignment of 10 degrees or more valgus or varus had the highest rates of satisfaction with surgery, compared to those within 10 degrees.