Outcomes and Satisfaction After Revision of Medial UKA for Unexplained Pain vs Aseptic Loosening

Overview

This nationwide Danish study compared patient-reported outcomes and satisfaction 1–3 years after revision of medial unicompartmental knee arthroplasties (mUKA) for unexplained pain versus aseptic loosening. Patients revised for unexplained pain reported significantly worse Oxford Knee Scores, EQ-5D-5L indices, and EQ VAS scores than those revised for aseptic loosening. These findings suggest limited benefit from revision surgery when the indication is unexplained pain.

Background

Medial unicompartmental knee arthroplasty (mUKA) is increasingly utilized but has higher revision rates compared to total knee arthroplasty (TKA). Common failure mechanisms include aseptic loosening and progression of osteoarthritis, yet a substantial proportion of revisions are performed for unexplained pain despite lack of radiographic pathology. Revision for unexplained pain is generally not recommended due to uncertain benefit. This study aimed to evaluate whether patients revised for unexplained pain have similar patient-reported outcomes and satisfaction as those revised for aseptic loosening.

Data Highlights

Key Findings

• Patients revised for unexplained pain had significantly worse Oxford Knee Scores compared to those revised for aseptic loosening (p=0.033).
• EQ-5D-5L health-related quality of life indices were significantly lower in the unexplained pain group (p=0.014).
• EQ Visual Analogue Scale (VAS) scores were also significantly lower for patients revised due to unexplained pain (p=0.013).
• Demographic characteristics such as age, sex, and BMI were similar between groups, minimizing confounding.
• Revision surgeries for unexplained pain often lack radiographic evidence of failure, questioning the indication for revision.
• Patient satisfaction and pain levels post-revision were generally poorer in the unexplained pain group.

Clinical Implications

Clinicians should exercise caution when considering revision surgery for mUKA patients presenting with unexplained pain, as these patients tend to have poorer outcomes and satisfaction compared to those revised for aseptic loosening. Thorough evaluation to exclude other causes and adherence to established revision indications may help avoid unnecessary surgeries. Patient counseling should include discussion of the limited expected benefit in cases of unexplained pain.

Conclusion

Revision of medial UKA for unexplained pain results in inferior patient-reported outcomes and satisfaction compared to revision for aseptic loosening. These findings underscore the need for careful patient selection and highlight that revision for unexplained pain may not provide meaningful clinical improvement.

References

1. Danish Knee Arthroplasty Register (DKR) -- Data on mUKA revisions 2018-2020
2. COSMIN Reporting Guideline -- Standards for PROM Studies
3. National Joint Registry of England and Wales -- UKA vs TKA revision indications