Knee Surgery, Sports Traumatology, Arthroscopy March 2017, Volume 25, Issue 3, pp 687–693

Early functional outcome after lateral UKA is sensitive to postoperative lower limb alignment

van der List, J.P., Chawla, H., Villa, J.C. et al.
Knee

Purpose

The predictive role of patient-specific characteristics and radiographic parameters on medial unicompartmental knee arthroplasty (UKA) outcomes is well known, but knowledge of these predictors is lacking in lateral UKA. Therefore, purpose of this study was to assess the predictive role of these parameters on short-term functional outcomes of lateral UKA.

 

Methods

In this retrospective cohort study, Western Ontario and McMaster Universities Arthritis Index scores were collected at 2-year follow-up (median 2.2 years, range 2.0–4.0 years) in 39 patients who underwent lateral UKA. Patient-specific characteristics included age, BMI and gender, while radiographic parameters included osteoarthritis severity of all three compartments and both preoperative and postoperative hip-knee-ankle alignment.

 

Results

BMI, gender, age and preoperative valgus alignment were not correlated with functional outcomes, while postoperative valgus alignment was correlated with functional outcomes (0.561; p = 0.001). Postoperative valgus of 3°–7° was correlated with better outcomes than more neutral (−2° to 3° valgus) alignment (96.7 vs. 85.6; p = 0.011). Postoperative alignment was a predictor when corrected for patient-specific characteristics (regression coefficient 4.1; p < 0.001) and radiological parameters (regression coefficient 3.8; p = 0.002).

 

Conclusions

Postoperative valgus alignment of 3°–7° was correlated with the best short-term functional outcomes in lateral UKA surgery, while patient-specific parameters and preoperative alignment were not correlated with functional outcomes. Based on these findings, a surgeon should aim for valgus alignment of 3°–7° when performing lateral UKA surgery for optimal functional outcomes.

 

Level of evidence

Prognostic study, Level II.


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