COLLAGEN MENISCUS IMPLANT (CMI) REGENERATED NEW TISSUE INCREASES ACTIVITY LEVELS AFTER TWO YEARS

INTRODUCTION: Absence of meniscus tissue leads to decreased clinical function and activity levels. In a previous study, we reported significant correlation between actual measured amounts of meniscus tissue removed at meniscectomy and symptoms, function and activity 2 years after surgery. In particular, it was noteworthy that patients with >50% remaining meniscus tissue were significantly better in all categories measured than patients with 50% total meniscus tissue at 1-year relook arthroscopy. METHODS: In a randomized controlled investigational device clinical trial (Level of Evidence I), 138 patients 18 to 60 years old underwent partial medial meniscectomy and placement of a CMI to fill the meniscus defect. There were 64 acute (no prior meniscus surgery) and 74 chronic (1 to 3 prior partial meniscectomies on the involved meniscus) patients. At index surgery, meniscus defect size was measured with specially designed instruments, and the percent of meniscus loss was calculated based on these actual measurements. Relook arthroscopy was performed at 1 year on 124 patients (90% surgical follow-up), and percent total meniscus tissue (remnant + new tissue) was determined by making these same measurements and calculations. Patients were followed clinically for a minimum of 2 years after CMI placement. At each follow-up, all patients completed questionnaires, including a Tegner score to assess activity. We then determined changes in Tegner score from the index surgery to 2 years status post CMI in these patients. RESULTS: Of 124 relooks, 111 patients (90%) had >50% total meniscus tissue. In these patients, average Tegner activity scores improved by two levels from 3 to 5 from preoperative to 2 years status post CMI. This increased change in activity levels significantly correlated with total meniscus tissue >50% (r=0.21, p=0.02). These findings mirrored those we previously reported for partial meniscectomy patients in which >50% of the meniscus was maintained. CONCLUSIONS: There is a significant correlation between change (increase) in Tegner activity levels over 2 years and percent total meniscus tissue in patients who receive the CMI as treatment for meniscus loss and have >50% total meniscus tissue. This study confirms the importance of preserving as much meniscus tissue as possible at the time of repair or meniscectomy. It clearly supports the potential positive benefits of regrowing or regenerating lost meniscus tissue to assist patients in regaining their activity.