The aim of this study is to provide evidence that the safety and effectiveness of the ceramic femoral component of the Gem Total Knee System is similar to FDA approved implants used in total knee replacement surgery. The hypotheses to be tested are that the investigational and control groups are equivalent in terms of patient success rate and complication-free rate.

Due to excellent biocompatibility and wear characteristics, ceramics have a long history of success in total hip arthroplasty (THA). Use of a ceramic-polyethylene wear couple in total knee arthroplasty (TKA) has shown promising laboratory and early clinical results. The use of ceramics in this study is intended to address long-term failure of TKA due to osteolysis associated with polyethylene wear debris.

Inclusion Criteria:

• Skeletally mature
• Primary TKA for osteoarthritis or post-traumatic arthritis of the knee joint
• Stable or reconstructable collateral and posterior cruciate ligaments
• Correctable deformity
• Intact quadriceps and hamstrings mechanisms
• Patella bone thick enough (at least 15 mm) after resection

Exclusion Criteria:

• Previous TKA
• Bilateral knee arthritis
• Non-availability for follow-up
• Mental incompetence or confinement
• Patients being treated with other investigational devices for same disorder
• Infection
• Osteoporosis, acute renal failure, or other disorders known to affect bone quality
• Charcot's or Paget's disease
• Patient physical condition preventing use of appropriate size implant
• Disease conditions affecting blood supply to knee
• Insufficient bone quality or quantity
• Physical condition predisposing implant to extreme loads
• History of septic knee arthritis
• History of drug abuse