The purpose of this study was to evaluate short-term clinical and MRI outcome of a polycarbonate-urethane meniscus implant for the treatment of medial compartment pain in middle aged patients.

In the younger population, (<40 yrs.) surgical options e.g., allograft transplants and artificial scaffolds are available and have been shown to be effective. For middle aged patients, the clinical benefit from surgical intervention of a degenerated meniscus has only been reported in a fraction of the patients. However, these patients are still too young for more aggressive treatments such as unicompartmental or total knee arthroplasty.

The meniscus implant is a non-degradable polymer-based spacer which is inserted into the medial compartment of the knee between the tibia and femur by a mini-arthrotomy, without requiring attachment or bone resection. It was hypothesized that the implant could relieve pain by restoring the pressure distribution function. This paper presents the first experience of 3 Israeli sites (out of 7 sites participating in the study).

Thirty patients aged 36 to 70 years were treated with the implant after signing an informed consent and meeting the criteria defined in the Ethics Committee approved protocol. All of the patients reported medial knee pain which was associated with either a severely degenerated meniscus (∼25%) or post-meniscectomy knee pain (∼75%). Patients with evidence of grade IV medial articular cartilage loss or instability were excluded from the study. Primary clinical outcome was measured by the KOOS scale over 12 months, with secondary outcomes measured by IKDC subjective, EQ-5D and VAS questionnaires for pain. Serial MRI scans were taken at 6 weeks and 12 months of follow-up to evaluate the condition of the articular cartilage.

The patients included in this study showed a considerable clinical improvement after the procedure. Significant pain relief was indicated by both KOOS pain subscale and VAS scores after 6 months follow up, and patient activity levels were also found to be higher following implantation. The first MRI findings from this study were considered to be promising since no signs of deterioration of the surrounding cartilage or of the device were observed. So far, one case of implant dislocation and two cases of infection have occurred among the 35 patients.

This study was designed to evaluate and obtain reasonable assurance of the safety, effectiveness, and risk/benfit ratio of a novel implant in the treatment of a challenging patient cohort. The short-term outcomes are promising.

Statement of Purpose

Meniscal tears are common knee injuries that subsequently lead to degenerative arthritis, attributed to changes in stress distribution in the knee. In such cases there is need to protect the articular cartilage by repairing or replacing the menisci. While traditionally, meniscal replacement involves implantation of allografts, problems related to availability, size matching, cost and risk of disease transmission limit their use. Another optional treatment is that of biodegradable scaffolds which are based principally on tissue engineering concepts. The variability in body response to biodegradable implants and the quality of the tissue formed still pose a problem in this respect, under intense knee loading conditions. Moreover, biological solutions are mostly limited to younger patients <40 years old. Therefore, the goal of this study was, to develop a synthetic meniscal implant which can replace the injured meniscus, restore its function, and relieve pain.