MRI evaluation of a collagen meniscus implant: a systematic review

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.

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.

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.

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.

IV.