MRI evaluation of a collagen meniscus implant: a systematic review

PURPOSE: Good clinical results have been demonstrated in numerous clinical studies using the collagen meniscus implant (CMI); however, the MRI behaviour of the scaffold, evaluated with Genovese score, is limited to a few cases series. The purpose was to evaluate, using the Genovese score, the MRI behaviour of the CMI at different follow-up periods and investigate possible differences in the behaviour of lateral and medial CMI. METHODS: A comprehensive search was performed on PubMed, Medline, CINAHL, Cochrane, Embase and Google Scholar databases using various combinations of the following keywords: "collagen meniscus implant" or "collagen meniscal implant". All the studies evaluating medial or lateral CMI using Genovese score for MRI were included in the systematic review. RESULTS: Six studies have been included in the systematic review, with no RCT's. The pooled number of patients involved in CMI surgery was 194 (83 % medial and 17 % lateral), with a mean age at surgery of 37.7 years. Concomitant procedures raged from 11 to 52 %. CMI morphology was grade 1 in 0, 2.7, 5.9, 0, 16.7 %, respectively, at 6 months, 1, 2, 5, 10 years. It was grade 2 in 12.5, 60.9, 60.3, 74.4, 75 %, respectively, at 6 months, 1, 2, 5, 10 years and grade 3 in 87.5, 36.4, 33.8, 25.6, 8.3 % at the same time points. CMI signal intensity was grade 1 in 80, 18.2, 25, 11.1, 22.2 %, respectively, at 6 months, 1, 2, 5, 10 years. It was grade 2 in 20, 78.2, 54.7, 55.6, 66.7 %, respectively, at 6 months, 1, 2, 5, 10 years and grade 3 in 0, 3.6, 20.3, 33.3, 11.1 % at the same time points. Slight differences were found between medial and lateral CMI in size and signal intensity. CONCLUSIONS: Higher rates of scaffolds with reduced size and with an MRI signal intensity more similar to normal meniscus were reported at longer follow-up compared with initial evaluations. Correlation between MRI findings and gross CMI appearance has not been reported. LEVEL OF EVIDENCE: IV.