Mechanics Analysis of Patients Having a Sigma Mobile Bearing TKA

Study Overview
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Brief Summary
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Utilize previously developed mathematical model to determine in vivo knee mechanics (kinematics, forces, stresses, areas and sound) for subjects having a Sigma Posterior Stabilizing (PS) mobile bearing (MB) total knee arthroplasty (TKA). There are several hypotheses for this study, although the most prominent is: Subjects having a Sigma RP PS TKA will experience polyethylene bearing rotation at 10 years post-operative, similar to their previous evaluations at six months, two years and five years.

Detailed Description
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Additional hypotheses: Subjects having a Sigma RP PS TKA will experience full ideal femorotibial contact mechanics. Subjects having a Sigma RP PS TKA will experience optimal cam/post mechanics. Subjects having a Sigma RP PS TKA will experience continuous axial rotation in deep flexion. Subjects having a Sigma RP PS TKA will experience optimal distribution of tibio-femoral and cam/post contact forces over a broad area on the post. Subjects having a Sigma RP PS TKA will experience a smooth transition of the cam on the post, not an abrupt slide as seen with fixed bearing PS TKA. The use of the sound sensors will detect cam/post contact mechanics under in vivo conditions.

Official Title
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In Vivo Mechanics Analysis of Patients Having a Sigma Mobile Bearing TKA

Conditions
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Knee Replacement Arthroplasty, Knee Prosthesis

Intervention / Treatment
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* Device: Sigma Posterior Stabilizing Rotating Platform TKA Beaded Poly


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: At least six months post-operative Between 40-85 years of age Have a body weight of less than 250 lbs. Judged clinically successful with a AKS greater than 90 Have the DePuy Sigma mobile bearing TKA Good-to-excellent post-operative passive flexion Must be willing to sign the IC and HIPAA forms. Exclusion Criteria: Pregnant females Those not willing to sign the IC and HIPAA forms

Ages Eligible for Study
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Minimum Age: 40 Years
Maximum Age: 85 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Sigma Posterior Stabilizing Rotating Platform TKA Beaded Poly<br>subjects implanted with the Sigma Posterior Stabilizing Rotating Platform TKA including a polyethylene insert with 4 beads | Device: Sigma Posterior Stabilizing Rotating Platform TKA Beaded Poly<br>* Sigma PS RP TKA including a polyethylene insert with 4 beads<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| In Vivo Linear Knee Kinematics From Fluoroscopy Evaluation During Deep Knee Bend Activity | The values that were reported indicate the motion of the contact point from full extension to patient's maximum flexion. Throughout flexion, if the point translated forward (anteriorly) atop the tibial tray, the number was reported as positive. If the point traveled backwards (posteriorly) atop the tibial tray, the number was reported as negative. | 10 yrs post-operative | 
| Femoral Axial Rotation With Respect to the Tibia During Deep Knee Bend Activity |  | 10 yrs post-operative | 
| Range of Motion During Flexion of Deep Knee Bend Activity |  | 10 yrs post-operative | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| In Vivo Knee Force Values From Fluoroscopy Evaluation During Deep Knee Bend Activity | The intended unit of measure is times Body Weight (or xBW), relating to a ratio. | 10 yrs post-operative | 
| Condyle Contact Area at Maximum Flexion During Deep Knee Bend Activity |  | 10 yrs post-operative | 
| Condyle Contact Stress at Maximum Flexion During Deep Knee Bend Activity |  | 10 yrs post-operative | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Total Knee Arthroplasty (TKA), in vivo mechanics, kinematics, fluoroscopy