The purpose of this study is to determine whether Chondrogen is a safe and effective post-operative treatment of the knee following menisectomy (the surgical removal of all or part of a torn meniscus).

Chondrogen is a preparation of adult mesenchymal stem cells (MSCs) in a solution containing hyaluronic acid. Preclinical studies have shown that injection of Chondrogen aids in the repair of meniscal tissue following meniscectomy. In Chondrogen treated subjects, surgically removed meniscal tissue was regenerated, cartilage surface was protected, and joint damage was decreased in comparison to control subjects. These benefits persisted at least one year.

Three groups of recent meniscectomy patients will be followed in this study, including patients that will receive placebo and patients that will be treated with one of two possible doses of Chondrogen.

Inclusion Criteria:

• Age 18 to 60, inclusive
• In need of medial meniscectomy
• Normal axial alignment
• Stable knee- previous ligament reconstruction, if stable
• Removal of at least 50% of the affected portion of the medial meniscus
• Intact articular cartilage in posterior meniscal weight-bearing zone
• Willingness to follow normal post-operative rehabilitation
• Willingness to participate in follow-up for two years from the time of meniscectomy surgery
• Ability to understand and willingness to sign consent form

Exclusion Criteria:

• Pregnant or lactating
• ACL or other support structure damage confirmed at surgery
• Grade III or IV cartilage damage (Cartilage loss greater than 50% thickness in area >15mm on weight-bearing aspect of femoral condyle or tibial plateau)
• Synvisc, steroid, or corticosteroid injections in preceding 3 months
• Diffuse synovitis at time of arthroscopy
• Inflammatory arthritis
• Oral steroid, methotrexate therapy
• Unable to follow post-operative exercise regimen or return for evaluations
• Active alcohol or substance abuse within 6 months of study entry
• Current and active tobacco product use
• Patient is positive for HIV
• Patient is positive for hepatitis (past history of Hepatitis A is allowed)
• Any medical condition, which in the opinion of the clinical investigator, would interfere with the treatment or outcome of the patient
• Indwelling pacemaker
• Cerebral aneurysm clips
• Ear, eye and penile implants with avian components
• Electrical indwelling device such as bone stimulator
• Indwelling magnets as tissue expander for future implants
• Known allergy to avian, bovine or porcine protein