RESUMEN
BACKGROUND: The purpose of this study was to determine if severe lateral patella facet osteoarthritis was related to lower survivorship and poor patient-reported outcomes following fixed-bearing lateral unicompartmental knee arthroplasty (UKA). METHODS: There were 61 patients who underwent a fixed-bearing, nonrobotically assisted, lateral UKA between May 7, 2003 and December 18, 2019 and met the inclusion criteria. The patello-femoral joint was examined intraoperatively for chondral damage prior to UKA implantation. Severe lateral facet patella osteoarthritis (LFPOA) was defined as Outerbridge grades 3 or 4 changes on the lateral facet. All patients completed subjective functional outcomes questionnaires and a clinical examination at a minimum of 4 years following UKA. RESULTS: Severe LFPOA was identified in 28 (46%) patients. At a mean follow-up of 10.9 years, there were no statistically significant differences in any Knee Osteoarthritis Outcomes Score (KOOS) subscale or Kujala scores between patients who had and did not have severe LFPOA. There was no statistically significant difference in the percentage of patients who achieved Patient Acceptable Symptom State for the KOOS subscale scores between groups. Mean survival in patients who did not have severe LFPOA was 16.6 years (95% confidence interval, 15.4 to 17.7) compared to 18.9 years (95% confidence interval, 17.6 to 20.2) in patients who had severe LFPOA (P = 0.62). CONCLUSIONS: Severe LFPOA did not result in lower survival or inferior functional outcomes compared to patients who did not have severe osteoarthritis at an average 10-year follow-up after fixed-bearing lateral UKA.
RESUMEN
BACKGROUND: Anterior cruciate ligament (ACL)-deficient knees are no longer considered a contra-indication for unicompartment knee arthroplasty (UKA). The purpose of this study was to determine if patients who had an ACL-deficient knee who underwent lateral UKA had similar mean 10-year outcomes compared to patients who had an ACL-intact knee and lateral UKA. METHODS: Patients who underwent a lateral UKA with ACL deficiency by a single surgeon between 2004 and 2016 were identified. Preoperative magnetic resonance images were utilized to identify a torn or absent ACL in all knees. The absence of an ACL was confirmed during arthroscopy prior to UKA. Patients were matched 1:2 based on age and sex with patients who underwent lateral UKA with an ACL intact knee. The primary patient-reported outcome variable was survival without conversion to total knee arthroplasty. Secondary outcomes included Veterans Rand-12, the Lysholm score, the Knee Osteoarthritis Outcome Score activities of daily living subscale, and Sport subscale. A power analysis showed that 14 patients were needed to identify differences of 10 points on the Knee Osteoarthritis Outcome Score with a power of 80% (P = .05). RESULTS: The cohort of patients who had an ACL-deficient lateral UKA included 4 men and 12 women (43 to 82 years of age). The matched control group included 32 patients. The mean age of both groups was 67 years (range, 43 to 85). There were 2 patients in the ACL-deficient group who failed. At 10 years, survivorship in the ACL-deficient group was 85%, while survival in the ACL-intact group was 100% (P = .035). At an average follow-up of 11 years (range, 4 to 19.6), there was no difference in outcome scores between ACL-deficient and ACL-intact patients. CONCLUSION: Fixed-bearing lateral UKA in the ACL-deficient knee resulted in lower survival than patients who had an intact ACL. Patient-reported outcomes were similar in both groups. The ACL-deficient patient who wishes to undergo lateral UKA should be counseled on the lower survival. LEVEL OF EVIDENCE: Level III. Retrospective cohort study.