The purpose of this study is to evaluate performance of two modern total knee arthroplasty designs using patient reported outcomes and force exhibited during various activities of daily living.

48 patients with primary osteoarthritis of the knee who have been appropriately designated for treatment with a total knee arthroplasty (TKA) will be randomly assigned to one of two groups; one group (24 patients) will receive a Depuy Attune PCR knee implant, and one group (24 patients) will receive a MicroPort Orthopedics Evolution Medial Pivot knee implant utilizing standard and modern techniques. These two implants are designed to recreate the kinematic motion of a native knee articulation using different biomechanical design philosophies.

The patients will be monitored post-operatively using subjective and objective measures. Subjective patient reported outcomes will be analyzed using the Knee Injury and Osteoarthritis Outcome Score (KOOS), recorded preoperatively, as well as at 6 weeks, and 3 months postoperatively. Objective outcomes will be measured by having the patients perform four activities over force plates that will measure the amount of force a patient generates. The four activities will be: walking, standing from a seated position in a chair, squatting to a seated position, and walking up stairs. These objective measures will also be recorded preoperatively, 6 weeks, and 3 months postoperatively. The patient reported outcomes and the objective measures will then be compared between the two groups.

Inclusion Criteria:

• Subjects who have been appropriately designated for treatment with a primary total knee arthroplasty
• Subjects who are willing to participate and are willing to sign the Informed Consent/HIPPA documents.

Exclusion Criteria:

• Subjects who are unsuitable candidates for the two types of knee implants under investigation.
• Subjects with significant deformities or arthritis that might affect the procedural decision making, expected outcomes and functions are total knee arthroplasty.
• Subjects with significant comorbidities that might be at an increased risk of post-operative complications.
• Subjects who are unwilling to sign Informed Consent/HIPAA documents.
• Subjects who cannot perform the required activities after the surgery.

The patient will be randomized to one of 2 treatment arms using a random number generator. The care provider will not be blinded as he will be implanting the device and following the patients' progress in clinic postoperatively, including radiographs which will show the implants. He will be blinded, however, to the results of the KOOS score and the data derived from the force plate analysis. The research assistants performing those assessments will be blinded to which treatment arm the patient belongs to.