Long-term survivorship after medial unicompartmental knee arthroplasty: the influence of medical comorbidities and previous knee surgery.

PURPOSE: To evaluate long-term implant survivorship after medial unicompartmental knee arthroplasty (UKA) and determine whether medical comorbidities or previous ipsilateral knee surgery were associated with revision, complications, or clinical outcomes.

METHODS

This retrospective cohort included 168 medial UKAs with a mean follow-up of 119.7 ± 29.3 months in the survivorship analysis. Revision of any prosthetic component was the endpoint for Kaplan-Meier analysis. A nested cohort of 76 knees underwent outpatient clinical evaluation; analyses of comorbidities, previous surgery, complications, and clinical outcomes were restricted to this cohort.

RESULTS

Eighteen revisions occurred. Implant survivorship was 100% at five years, 96% at seven years, 86% at ten years, and 78% at 15 years. In the 76-knee clinical cohort, 92.1% had at least one comorbidity and 54.0% had multimorbidity; no evaluated comorbidity category was significantly associated with revision or long-term clinical outcomes. Previous ipsilateral knee surgery was associated with a lower Knee Society clinical score (73.6 ± 14.1 vs 80.7 ± 12.5; p = 0.036) and a non-significantly higher rate of complication or revision (28.6% vs 8.1%; odds ratio 4.56; p = 0.054).

CONCLUSION

Medial UKA provided satisfactory long-term survivorship in a real-world cohort. No clear association was identified between the evaluated comorbidity categories and long-term outcomes, although small subgroups and the absence of severity measures preclude definitive conclusions. Previous ipsilateral knee surgery was associated with a lower objective clinical score and may identify knees requiring more cautious pre-operative counselling.