Clinical Outcomes of MP Persona vs. Persona Knee-PS

nee motion will be assessed using 3-dimensional optical motion capture sampled at 100 Hz, floor and step mounted force plates sampled at 2000 Hz, and wireless 16-channel electromyography (EMG) system sampled at 2000 Hz.

Knee motion trials will require participants to ambulate at self-selected speeds over 8 meters followed by complete step up/down trials on a 20 cm step. For step up, the surgical limb will be placed on the step to start while for step down, both limbs will start on the step. The order of step up and down trials will be randomized. Participants will perform 2 practice trials followed by testing. Testing will proceed until 5 successful trials of each activity are collected. They will be allowed 30 seconds of rest between trials.

The primary motion capture variables will include principal component scores that capture changes in range of motion for knee rotation and flexion angles for each activity.

Muscle activation will be measured by surface electrodes placed bilaterally over the following muscles: vastus lateralis and medialis, rectus femoris, lateral (biceps femoris) and medial (semitendinosus) hamstrings, and lateral and medial gastrocnemius. The isometric exercises will include: 1) knee extension in sitting with the knee in 45 degrees of flexion; 2) knee flexion in sitting with the knee at 55 degrees of flexion; 3) ankle plantarflexion in long sitting with the ankle in neutral; and 4) standing unilateral heel rise. Participants will perform 1 practice and 2 collection trials for each exercise. They will be allowed 30 seconds of rest between trials.

Participants will be asked to complete "the 30 seconds Chair Test", a physical function performance test measuring the maximum number of sit-to-stand repetitions on a standard chair with a seat height = 46 cm.

After resting for 5 minutes, the participants will be asked to complete "the Stair Climb Test", a physical function performance test assessing the time [seconds] to ascend and descend a 11-step stair, each step 16 cm high.

After resting for 5 minutes, the participants will be asked to complete "the 6 Minutes Walk Test", a physical function performance test measuring the distance [meters] ambulate in 6 minutes. The participants will be allowed to rest during the test but the timer will not be stopped.

Participants will be asked to complete the "Knee Osteoarthritis and Outcome Score (KOOS)" questionnaire. The KOOS's five patient-relevant dimensions are scored separately: Pain (nine items); Symptoms (seven items); ADL Function (17 items); Sport and Recreation Function (five items); Quality of Life (four items). A Likert scale is used, and all items have five possible answer options scored from 0 (No problems) to 4 (Extreme problems) and each of the five scores is calculated as the sum of the items included. Scores are transformed to a 0-100 scale, with zero representing extreme knee problems and 100 representing no knee problems as common in orthopedic scales and generic measures. Scores between 0 and 100 represent the percentage of total possible score achieved.

Participants will be asked to complete the "EQ-5D-5L" questionnaire, a measure of health-related quality of life that comprises five dimensions: mobility, self-care, usual activities, pain/discomfort and anxiety/depression. Each dimension has 5 levels: no problems, slight problems, moderate problems, severe problems and extreme problems. The patient is asked to indicate his/her health state by ticking the box next to the most appropriate statement in each of the five dimensions. This decision results in a 1-digit number that expresses the level selected for that dimension. The digits for the five dimensions can be combined into a 5-digit number that describes the patient's health state.

Participants will be asked to complete the GRC questionnaire to rate the improvement or deterioration over time compared to the pre-operative visit. The GRC is a 15-point scale (-7=Worse, +7=Better) to assess the participant current health status, recall that status at a previous time-point, and then calculate the difference between the two. The magnitude of this difference will be scored on a numerical or visual analogue scale.

Sensitivity to Physical Activity will quantify the pain response to standardized physical activity. Participants will be required to rate their pain before and after each Physical Function Performance Tests using a 0 (no pain) to 100 (most pain imaginable) numeric rating scale. To determine the SPA for each test, the pain before the test will be subtracted from the pain after the test.

Radiographs (anteroposterior hip to ankle, standing anteroposterior; standing lateral and patellar axial views) will be taken pre-operatively, intra operatively and at 6 weeks, 1 year and 2 years post-operatively as part of standard care. Radiographic evaluation will consist of the assessment of limb alignment, component position, and presence of radiolucencies or osteolysis. Longitudinal changes of posterior femoral condylar offset and the degree of posterior tibial slope after the surgery will be also determined.

Adverse events and unplanned hospital visits will be tracked and documented. This includes wound related problems (infections), deep vein thrombosis, pulmonary embolism, stiffness, implant loosening, implant instability, re-operation or removal of any components for any reason.

Following gait trials, participants will complete a series of four maximum voluntary isometric contractions (MVIC) as follows: 1) knee extension in sitting with the knee in 45o of flexion; 2) knee flexion in sitting with the knee at 55o of flexion; 3) ankle plantarflexion in long sitting with the ankle in neutral; and 4) standing unilateral heel rise. MVIC exercises 1-3 will be performed on an isokinetic dynamometer. Participants will perform 1 practice and 2 collection trials for each exercise. They will be allowed 30 seconds of rest between trials. The MVIC will be used to normalize the amplitude of EMG waveforms.