Introduction: The Collagen Meniscus Implant (CMI) has been shown to be effective for the replacement of lost medial meniscus tissue; however, no such device has been available for treatment of similar injuries to the lateral meniscus. Loss of the lateral meniscus results in a rapidly increased rate of knee degeneration compared to similar medial injuries. The purpose of this study was to determine if a CMI developed for use in treatment of lateral meniscus deficiencies is as safe and effective as has been reported for the medial CMI.

Methods: Prospectively, 60 patients (12–65 years of age) were enrolled at 7 sites between March 2006 and October 2007. Patients had irreparable lateral meniscus tears requiring partial meniscectomy. The knee had to be ligamentously stable and in neutral alignment and with no untreated Grade IV cartilage damage. Patients gave informed consent and agreed to comply with postoperative assessments and standardized rehabilitation. The surgical technique involved insertion of the dry implant into the lateral compartment of the knee joint. Fixation of the implant to the host meniscus rim was accomplished with either an all-inside suture technique or a hybrid all-inside/inside-out technique. Clinical evaluations and patient self-assessments were conducted preoperatively and at defined intervals through 2 years postoperatively. Procedure specific intraoperative parameters, radiographic evaluations, and adverse events were documented. Data collection was monitored by a third party according to GCP regulations.

Results: 49 patients received a lateral CMI. Currently, 24 patients have 1-year follow-up and 13 patients have been followed approximately 2 years; the mean follow-up is 22 months. Follow-up included assessments of changes in Lysholm, pain, Tegner and patient satisfaction. All patients showed clinical improvement from the preoperative to the 1 year postoperative time points. Four patients experienced adverse events which required an additional arthroscopic procedure between 4 and 16 months and included removal of implant remnants, synovectomy and debridement.

Conclusions: These preliminary results appear to suggest that implantation of lateral CMI leads to improved clinical outcomes in pain, function, self-assessment and activity levels. Frequency and type of adverse events are comparable to those for suture repair reported in the literature. Based on results reported for the medical CMI, we anticipate that these lateral CMI patients will have improved long-term results compared to partial lateral meniscectomy.