The goal of this study is to compare the fixed bearing (FB) Triathlon knee (Stryker, USA) and the mobile bearing (MB) Triathlon knee (Stryker, USA) and study the effect of implant design on kinematics and micromotion. During two tasks the kinematics measured with fluoroscopy (kinematics and movement of the polyethylene bearing). Roentgen Stereophotogrammetric Analysis (RSA) will be used to evaluate micromotion between prosthesis and the bone for the MB and FB Triathlon knee.
The goal of this study is to perform a kinematic evaluation of a MB and FB knee prosthesis designs (Triathlon, Stryker, USA), by means of fluoroscopy and RSA and compare the different designs. The findings of this study will contribute to improve total knee designs and improve rehabilitation strategies. Objectives: 1. To evaluate if there is micromotion of the prosthesis with respect to the bone and if there is a different migration pattern between the designs. 2. To assess and compare the in vivo kinematic patterns of the knee designs by means of fluoroscopy. This will be done on a subset of the patients (the first 20 patients able to perform step-up and lunge motions 6 months post-operatively in a controlled manner without the use of bars and walk more than 1 km) 3. To evaluate if the polyethylene bearing in the mobile bearing is rotating and if this changes over time. 4. Results of the RSA study will be used to correlate the kinematic parameters (fluoroscopy) with the migration results in order to identify factors of risk for the survival of total knee prostheses.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
SINGLE
Enrollment
48
Department of Orthopaedics, Leiden University Medical Center
Leiden, Netherlands
Migration, measured by means of RSA on the first 20 patients (fluoroscopy subset)
Migration (MTPM in mm) of the prosthesis with respect to the host bone measured by means of roentgen stereophotogrammetric analysis (RSA)
Time frame: First or second day postoperatively, 6 months, 1 year
Migration, measured by means of RSA
Migration (MTPM in mm) of the prosthesis with respect to the host bone measured by means of roentgen stereophotogrammetric analysis (RSA)
Time frame: First or second day postoperatively, 6 months, 1 year and annually thereafter up to 20 years
Assessment of the knee flexion range by means of fluoroscopy during step-up motions
Patients will be asked to perform three step-up motions (height 18 cm) with bare feet in front of a flat panel fluoroscope. Outcome measurement is knee flexion range (degrees).
Time frame: 6 months and 13 months postoperatively
Assessment of the axial rotation range of femoral component by means of fluoroscopy during step-up motions
Patients will be asked to perform three step-up motions (height 18 cm) with bare feet in front of a flat panel fluoroscope. Outcome measurement is axial rotation range of femoral component (degrees).
Time frame: 6 months and 13 months postoperatively
Assessment of the knee flexion range by means of fluoroscopy during lunge motions
Patients will be asked to perform three lunge motions (height 18 cm) with bare feet in front of a flat panel fluoroscope. Outcome measurement is knee flexion range (degrees).
Time frame: 6 months and 13 months postoperatively
Assessment of the axial rotation range of femoral component by means of fluoroscopy during lunge motions
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Patients will be asked to perform three lunge motions (height 18 cm) with bare feet in front of a flat panel fluoroscope. Outcome measurement is axial rotation range of femoral component (degrees).
Time frame: 6 months and 13 months postoperatively
Investigation of clinical performance and patient outcome with the Knee Society Score (KSS)
The Knee Society Clinical Rating System is comprised of two distinct sub-scores: one for pain, range of motion (ROM) and joint stability, and one for functional parameters. Sub-scores range from a potential minimum score of 0 to a maximum score of 100 points. Although the specific scores are not distinguished as "excellent," "good," "fair," or "poor," a higher value represents a better outcome.
Time frame: Within 3 months prior to surgery, 6 months postoperatively, 1 year and and annually thereafter up to 20 years