In Vivo Kinematics Comparison of Stryker or Zimmer Total Knee Arthroplasty

A better understanding of knee joint kinematics is important to explain premature polyethylene wear failures within knee implants and to help design a prosthesis that most closely approximates the normal knee. Therefore, the objectives for this study are to compare the in vivo kinematic patterns for subjects implanted with either a Stryker Triathlon Posterior Cruciate Retaining (PCR) Total Knee Arthroplasty (TKA) or Zimmer NexGen PCR TKA design to determine if there are any kinematic differences between these TKA designs. Each subject will be asked to undergo a fluoroscopic evaluation while performing weight-bearing activities under surveillance using the University of Tennessee's new mobile tracking fluoroscopic unit while performing deep knee bend and ramp up and ramp down activities. The mobile fluoroscopy unit is approved for use by the State of Tennessee on a study-by-study basis after IRB approval is obtained for each study.

Inclusion criteria

• Must be at least 3 months post-operative with no other surgical procedures conducted within the past 6 months
• Must have body weight of less than 250 lbs
• Must have Body Mass Index of less than 38
• Must be judged clinically successful with a Knee Society Score >90
• Must have 100% post-operative passive flexion with no ligamentous laxity or pain
• Must be able to walk on level ground without aid of any kind
• Must be able to ascend and descend a ramp with a 10 degree incline with no assistance
• Must be willing to sign both Informed Consent and HIPAA forms
• Must be between 160 cm (5'3) and 193 cm (6'4) tall

Exclusion criteria

• Pregnant or potentially pregnant females
• Unwilling to sign Informed Consent or HIPAA forms