Minor valgus under correction may not affect short-term outcome after TKA

Liang Zhou et al conducted a study to investigate the effect of different degrees of valgus deformity correction on patellar position and clinical outcome in patients with valgus knees after total knee arthroplasty (TKA).It has been published in ‘International Orthopaedics’ journal.

The authors retrospectively analyzed and followed 118 patients with valgus knees. Based on the post-operative hip–knee–ankle (HKA), patients were divided into three groups: neutral (±3°), mild (3–6°), and severe (> 6°). Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), range of motion (ROM), and Knee Society Score (KSS) were used to evaluate post-operative clinical efficacy. Also, the patellar tilt angle (ε-angle), congruence angle (θ-angle), and Insall–Salvati index (ISI) were used to represent the patellar position. Post-operative observation indicators included HKA, angle of the femur (α-angle), tibial angle (β-angle), femoral component flexion angle (γ-angle), and tibial component posterior slope angle (δ-angle).

Key findings of the study were:

• All patients showed significant improvements in HKA, ROM, WOMAC, and KSS after operation (P < 0.001).

• Regarding patellar position, the ISI values decreased to varying degrees (P< 0.05).

• The patellar tilt angle was significantly increased in the severe valgus group compared to that in the mild valgus and neutral groups (P <0.001).

• Univariate analysis showed that the degree of post-operative residual valgus was significantly affected by WOMAC, KSS, α-, ε-, and θ-angles.

The authors concluded – “the degree of correction of lower limb alignment after TKA is associated with the clinical effect and will affect the position of the patella; however, a slight insufficient correction will hardly affect short-term clinical efficacy. Moreover, excessive post-operative residual valgus (> 6°) will affect short-term clinical efficacy, and an insufficient correction may increase the risk of poor patellar tracking. Finally, although the height of the patella decreased to different degrees after TKA, the degree of correction did not affect the degree of height reduction.

Further reading:

Efect of total knee arthroplasty for valgus knee correction on clinical outcome and patellar position

Liang Zhou, Xuening Dai et al

International Orthopaedics (2023) 47:735–743

https://doi.org/10.1007/s00264-023-05689-x