Similar Functional Results in Patients Outside the Classical Criteria for Medial Unicompartmental Knee Arthroplasty.

BACKGROUND

The indications for unicompartmental knee arthroplasty (UKA) are restricted by multiple criteria. The aim of this study was to explore the functional results of UKA in a population of patients outside the classical criteria.

METHODS

This study included a population of 197 patients who underwent UKA for medial osteoarthritis between 2017 and 2020. Two groups of patients were compared: those meeting the classical criteria and those presenting with ≥1 contraindication (e.g., age of ≥75 years, body mass index [BMI] of ≥30 kg/m 2 , or coronal limb deformity of >8°). The implant that was used was a modern fixed-bearing primary medial UKA component. The minimal follow-up was 3 years. The primary outcome was the functional results, including the Knee Society Score (KSS), and the secondary outcomes were the complication and revision rates.

RESULTS

There were 100 patients in the indication group and 97 in the off-indication group. No significant differences were observed between the 2 groups for height, sex ratio, operated side, or osteoarthritis stage (p > 0.05). There was no significant difference in the KSS between the 2 groups (p = 0.96). At 3 years of follow-up, the survival rate without revision was 100% in the indication group and 95.38% in the off-indication group (p = 0.57). The rate of complications was 12.9% in the indication group and 8.96% in the off-indication group (p = 0.47).

CONCLUSIONS

UKA for medial osteoarthritis yielded the same functional results for patients presenting with ≥1 theoretical contraindication, including a BMI of ≥30 kg/m 2 , age of ≥75 years, and coronal limb deformity of >8°, without altering the complication or revision rates at 3 years of follow-up.

LEVEL OF EVIDENCE: Therapeutic Level III . See Instructions for Authors for a complete description of levels of evidence.