In Vivo Determination of 3D Patellofemoral Mechanics

Study Overview
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Brief Summary
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This study will analyze the tibio-femoral and patellofemoral (motion) and mechanics (forces) of participants having a normal knee or a total knee arthroplasty (TKA) using one or two different (TKA) devices Low Contract Stress (LCS) Posterior Stabilizing (PS) Rotating Platform (RP) Total Knee Arthroplasty (TKA). All knees will be analyzed using an image matching technique that will convert a two-dimensional (2D) fluoroscopic image into a three-dimensional (3D) image. In conjunction with the fluoroscopic analysis, electromyography (EMG) data, and ground reaction force (GRF) data will all be allow for a complete analysis of the knee joints. These results will help the orthopaedic community better understand knee motion so they can improve testing on existing implants and develop future implants that will further enhance patients' lives.

Official Title
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In Vivo Determination of 3D Patellofemoral Mechanics

Conditions
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Knee Prosthesis, Arthroplasty Replacement Knee

Intervention / Treatment
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* Device: Subjects implanted with DePuy LCS PS RP TKA
* Device: Subjects implanted with DePuy Sigma PS RP TKA


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Patients must be at least six months post-operative. Potential subjects will have a body weight of less than 250 lbs. Candidates must have an AKS score >70 post-operatively. Patients must have passive flexion of at least 100. Implanted group must have either an LCS PS RP TKA, having an anatomical patella, or Sigma PS RP TKA; or normal knee group must have normal knee. Must be willing to sign both Informed Consent and HIPAA forms. Exclusion Criteria: Pregnant females. Subjects not meeting study requirements.

Ages Eligible for Study
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Minimum Age: 20 Years
Maximum Age: 85 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Knee Prosthesis LCS PS RP TKA<br>Subjects implanted with DePuy Low Contact Stress (LCS) Poster Stabilizing (PS) Rotating Platform (RP) Total Knee Arthroplasty (TKA) | Device: Subjects implanted with DePuy LCS PS RP TKA<br>* Subjects implanted with DePuy Low Contact Stress (LCS) Poster Stabilizing (PS) Rotating Platform (RP) Total Knee Arthroplasty (TKA)<br>|
| Knee Prosthesis Sigma PS RP TKA<br>Subjects implanted with a DePuy Sigma Posterior Stabilizing (PS) Rotating Platform (RP) Total Knee Arthroplasty (TKA) | Device: Subjects implanted with DePuy Sigma PS RP TKA<br>* Subjects implanted with a DePuy Sigma Posterior Stabilizing (PS) Rotating Platform (RP) Total Knee Arthroplasty (TKA)<br>|
| Control<br>Subjects with normal knees | |

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Patella Flexion With Respect to Femur | Full extension to maximum flexion. Degrees of flexion analyzed for participants with and without implants. | Average post-operative time for LCS-PS group was 56 months. Average post-operative time for PS RP group was 55.7 months. | 
| Patella Rotation With Respect to Femur | Patellar rotation from full extension to maximum flexion for subjects with and without implants. A positive measurement of patellar rotation refers to positive flexion of the patella about the medial-lateral axis, where the patella component rotates so that the top of the patella rotates toward the femur and the bottom rotates away. Conversely, a negative measurement refers to negative flexion of the patella about this axis, where the patellar component rotates so that the top of the patella moves away from the femur and the bottom moves towards. | Average post-operative time for LCS-PS group was 56 months. Average post-operative time for PS RP group was 55.7 months. | 
| Patella Tilt With Respect to Femur | full extension to maximum flexion for participants with and without implants. | Average post-operative time for LCS-PS group was 56 months. Average post-operative time for PS RP group was 55.7 months. | 
| Normalized Medial Patella Contact Point Translation | full extension to maximum flexion for participants with and without implants. Position of the patellar contact point was determined by locating the closest point to the femur on the patella throughout flexion. There are 2 patello-femoral contact points: a point on the medial aspect of the patella and a point on the lateral aspect of the patella. Throughout flexion, the medial contact point generally moves closer to the top of the patella (hence the positive value for the results). The translation of this contact point is normalized to report a ratio between -1 and 1. In other words, the distance the point has traveled compared to the total height of the patella. For example, if the patella is 8 cm in height and the point travels approximately 2 cm upwards during flexion, the value would be reported as +2/8 = +0.25. Definition of normalized: multiply (a series, function, or item of data) by a factor that makes the norm or some associated quantity such as an integral equal | Average post-operative time for LCS-PS group was 56 months. Average post-operative time for PS RP group was 55.7 months. | 
| Normalized Lateral Patella Contact Point Translation | full extension to maximum flexion for participants with and without implants. Position of patellar contact point was determined by locating closest point to femur on patella throughout flexion. There are 2 patello-femoral contact points: 1 point on the medial aspect of the patella and 1 point on the lateral aspect of the patella. Throughout flexion, lateral contact point generally moves closer to the top of the patella (hence, the positive value for the results). The translation of this contact point is normalized to report a ratio between -1 and 1. The distance the point has traveled compared to the total height of the patella. For example, if the patella is 8 cm in height and the point travels approximately 2 cm upwards during flexion, the value would be reported as +2/8 = +0.25. Definition of normalized: multiply (a series, function, or item of data) by a factor that makes the norm or some associated quantity such as an integral equal to a desired value (usually 1). | Average post-operative time for LCS-PS group was 56 months. Average post-operative time for PS RP group was 55.7 months. |