This study has been designed to document the long-term outcome of the E1® Tibial Bearings used with the Vanguard® Knee System in 500 patients receiving total knee arthroplasty. All patients will receive the E1® Tibial Bearing in a Vanguard® knee replacement. Radiographic analysis and patient reported outcomes will be used as follow-up measures to track wear, mechanical performance, and patient satisfaction.

Inclusion Criteria:

• Male or Female
• 20 to 75 years of age
• Subjects requiring total knee replacement
• Subjects with the diagnosis of osteoarthritis, or traumatic arthritis
• Subjects who demonstrate the ability to return to Massachusetts General Hospital for follow-up for the next 10 years

Exclusion Criteria:

• Subjects with osteoporosis, osteomalacia, or neuromuscular disease
• Incomplete or insufficient soft tissue around the knee
• Subjects with a limited life span
• Subjects who have difficulty comprehending the study protocol for any reason
• Subjects with disorders which may impair bone formation
• Subjects whose bony structure deviates substantially from the general norm
• Female subjects that are, or may become, pregnant while participating in this study