Arthritic progression secondary to meniscus root tear treated with knee arthroplasty demonstrates similar outcomes to primary osteoarthritis: a matched case–control comparison

Purpose: There is limited data comparing the outcomes of knee arthroplasty for arthritis secondary to meniscus root tear versus primary osteoarthritis. The aim of this 2:1 matched case control series was to compare outcomes in patients who underwent arthroplasty for arthritis following a meniscus root tear (root tear cohort—“RTC”) with a control group of patients with primary osteoarthritis (primary osteoarthritis—“controls”). The authors hypothesized that the meniscus root tear patients would have similar clinical outcomes, return to activity, complication and reoperation rates as their matched controls. Methods: A consecutive series of patients who had a clinically and radiographically confirmed meniscus root tear between 2002 and 2017 at a mean 4.8 year follow-up that developed secondary arthritis were matched 2:1 by laterality, surgery, age at surgery, date of surgery, sex, and surgeon to a control group of patients with primary osteoarthritis, without a root tear, who underwent arthroplasty. No patients were lost to follow-up. Patient demographics, Kellgren–Lawrence grades at the time of surgery, pre- and post-operative Knee Society Score pain and function scores, Tegner score, complications, and survival free of reoperation were analyzed between groups. Results: A total of 225 subjects were identified, including 75 root tear cohort patients (13 UKA, 62 TKA) and 150 control patients. The root tear cohort had significantly lower Kellgren–Lawrence grades than the control group at the time of arthroplasty (p ≤ 0.001), but similar baseline pre-operative Knee Society Score pain, Knee Society Score function, and Tegner activity scale score. Post-operatively, Knee Society Score pain scores were comparable, and root tear cohort Knee Society Score function scores statistically significantly improved (p ≤ 0.007). Complication rates and survival free of reoperation at final follow-up were not statistically significantly different between groups. Conclusion: Patients treated with arthroplasty for secondary arthritis after a meniscus root tear demonstrated less severe radiographic arthritis, but similar pre-operative pain levels compared to matched controls with primary osteoarthritis. The root tear cohort patients demonstrated improved outcomes with respect to function, and similar outcomes with respect to pain, activity level, complication rates, and reoperation rates. The authors conclude that arthroplasty can be a reliable option for selected patients with an irreparable root tear and ongoing pain and dysfunction refractory to non-operative management, even in the setting of less advanced osteoarthritis on X-ray. Level of evidence: III.