Gait Analysis of a Lateral-Pivot Design Total Knee Replacement

Previous motion analysis studies have demonstrated excellent ability to distinguish subtle differences in gait between normal subjects and those suffering from arthritis. With proper techniques and analysis differences between osteoarthritis patient groups can be distinguished. Previous research has indicated that subjects who received a single-radius design total knee replacement have superior gait performance that those who received a multi-radius design total knee replacement. The DJO Global Empowr PS Knee System is a single-radius lateral pivot design. This design should achieve reproducible more natural knee function and improved patient outcomes and satisfaction. A motion analysis laboratory will be used to collect gait data from patients who are going to receive a Empowr PS knee device and also from age-matched control subjects. These data will be compared with data previously collected from patients who received Stryker Triathlon devices, Biomet Vanguard devices and age-matched healthy control subjects.

Thirty subjects who are scheduled to receive an Empowr PS Total Knee Replacement device will be consented to be in the prospective component of the study. Twenty of these patients will participate in motion data collection. These patients will all be scheduled to undergo primary total knee replacement using the Empowr device. All surgeries will be performed using computer navigation. Patients will receive standardized physical therapy to insure consistency of rehab protocols and discharge from physical therapy criteria. Specifically, patients will be monitored for visit compliance, Timed Up and Go (TUG) test in seconds, AROM in degrees, and walking un-aided.

Data were previously collected preoperatively, at 6 months and 1 year post-operatively for 16 patients who received a Stryker Triathlon total knee replacement and preoperatively and 1 year post-op for 16 patients who received a Biomet Vanguard total knee replacement. Data were also previously collected for 20 age matched healthy controls subjects. Data will be collected for an additional 20 control subjects. Knee Society Score (KSS) and Knee Injury and Osteoarthritis Outcome Score (KOOS) will be collected at pre-op, 6 months, 1 year, and 2 years post-op. Gait analysis data will include kinetic, kinematic, temporal spatial, and electromyographic (EMG) data throughout the gait cycle for both research subjects and controls. Reflective markers will be placed on subject's anatomical landmarks, and ten surface EMG electrodes placed according to published standards (8). Subjects will walk at a self-selected speed down a runway embedded with force plates while 10 Eagle-4 digital infrared cameras record their movement. In addition to the level surface walking, additional data on more complex activities of daily living will be collected for potential future analysis. This would include: sit-to-stand, balance, and stair-climbing measurements also using the force plates, camera system and EMG data collection.

Eligibility Criteria:
Inclusion Criteria:

Controls:

1. At least 50 years of age.
2. Subjects who provide signed and IRB approved informed consent for gait analysis data collection

Retrospective subjects:

1. Subjects who had primary total knee replacement with either Stryker Triathlon Total Knee System or Biomet Vanguard Complete Knee System.
2. Subjects at least 50 years of age at the time of the surgery.
3. Subjects who previously provided signed and informed consent for gait analysis data collection under approval of the Sun Health Institutional Review Board
4. Cases that followed product labeling.

Prospective subjects:

1. Subjects who are eligible for DJO Global's Empowr total knee replacement.
2. Subjects at least 50 years of age at the time of the surgery.
3. Subjects who are willing to provide signed and IRB approved informed consent for gait analysis data collection.
4. Cases that followed product labeling.

Exclusion Criteria:

Controls:

1. Controls with any musculoskeletal injury or disorder.
2. Controls that are pregnant or planning on becoming pregnant.
3. Controls with a BMI\>40

Retrospective subjects:

1. Subjects with inflammatory arthritis or psoriatic arthritis at the time of surgery.
2. Subjects that are pregnant or planning on becoming pregnant.
3. Subjects with a BMI\>40
4. Subjects who had an active infection or suspected latent infection in or about the joint at the time of surgery.
5. Subjects whose bone stock was compromised by disease, infection or prior implantation which could not provide adequate support and/or fixation of the prosthesis.
6. Subjects who had any mental or neuromuscular disorders which created an unacceptable risk of prosthesis instability, prosthesis fixation failure, or complication in postoperative care.
7. Subjects with severe instability of the knee joint secondary to the absence of collateral ligament integrity and function.

Prospective subjects:

1. Subjects with inflammatory arthritis or psoriatic arthritis at the time of surgery.
2. Subjects that are pregnant or planning on becoming pregnant.
3. Subjects with a BMI\>40
4. Subjects who had an active infection or suspected latent infection in or about the joint at the time of surgery.
5. Subjects whose bone stock was compromised by disease, infection or prior implantation which could not provide adequate support and/or fixation of the prosthesis.
6. Subjects who had any mental or neuromuscular disorders which created an unacceptable risk of prosthesis instability, prosthesis fixation failure, or complication in postoperative care.
7. Subjects with severe instability of the knee joint secondary to the absence of collateral ligament integrity and function.