Ongoing MRI remodeling 3-7 years after collagen meniscus implantation in stable knees

Purpose The purpose of the present study was to evaluate the clinical and radiological 3-7 years outcomes of patients who underwent collagen meniscus implantation in stable or stabilized knees. It was the hypothesis that using the collagen meniscus (CMI) good clinical 3-7 years outcomes with low pain levels are achieved. Methods Thirty-nine patients (male:female = 30:9, mean age 34 +/- 10 years) underwent arthroscopic CMI after subtotal medial (n = 32) or lateral meniscectomy (n = 7). A 7-mm CMI was performed due to prophylactic (n = 25) or therapeutic indication (n = 14). IKDC score, Tegner score preinjury, preoperatively and at follow-up, Lysholm score and visual analogue scale for pain and satisfaction (follow-up rate 90%) were assessed. MRI scans were analyzed according to the Genovese criteria (n = 19). Implant failure was defined as infection or mechanical failure of the device. The minimum follow-up time was 36 months (range 36-84 months). Results The mean VAS satisfaction preoperatively and at follow-up was 4.0 +/- 0 and 1.6 +/- 1.0. The mean VAS pain was 4.3 +/- 3.2 preoperatively and at last follow-up 2.1 +/- 1.7. The median Tegner score preinjury was 7 (range 3-10), it decreased preoperatively to median 3.5 (range 1-8) and nearly reached the preinjury level at last follow-up 6 (range 3-10). The mean Lysholm score before surgery was 66 +/- 20 and 91 +/- 8 at last follow-up. Seven patients (38.9%) had a normal total IKDC score (A), 10 patients were nearly normal (B) and 1 patient slightly abnormal (C). In MRI the CMI was entirely resorbed in 4 patients (21%) and partially resorbed in 15 (79%). In 4 patients (21%) the CMI was isointense, in 14 (74%) slightly hyperintense and in 1 (5%) highly hyperintense. Ten patients (53%) showed marked signs of bone marrow edema. In 13 patients (68%) an extrusion of the meniscus > 3 mm at last follow-up was found. Conclusions Meniscal substitution with the CMI showed good to excellent clinical 3-7 results. The CMI shows an ongoing remodelling with decreased signal intensity and decreased size. However, as meniscus extrusion remained at the same level and bone marrow edema decreased from 1 year to longer term follow-up, it appears that the remodeling comes to an end at about 5 years after CMI.