Surgeons performing a total knee replacement (TKR) have two available techniques available to help them achieve the proper bone resections and ligament tension – gap balancing (GB) and measured resection (MR). GB relies on balancing ligaments prior to bony resections whereas bony resections are made based on anatomical landmarks in MR. Many studies have been done to compare the joint kinematics between the two techniques, however the results have been varied. These studies were not done with anatomically designed prostheses. The Journey II (Smith & Nephew, Memphis, TN) is one such design which attempts to mimic the normal knee joint structure to return more natural kinematics to the joint, with emphasis on eliminating both paradoxical anterior motion and reduced posterior femoral rollback. Given the design differences between anatomical and non-anatomical prostheses, it is important to investigate whether one technique provides superior kinematics when an anatomical design is used. We hypothesize that there will be no difference between the two techniques. A total of 56 individuals were recruited to receive a Journey II prosthesis and randomized evenly to groups where the GB technique or MR technique is used. For all patients in the study, a series of radiostereometric analysis (RSA) images were acquired at 3-months post-operatively at different knee flexion angles, ranging in 20° increments from 0° to 120°. Model-based RSA software (RSACore, Leiden, Netherlands) was used to obtain the 3D positions and orientations of the femoral and tibial implant components, which were in turn used to obtain kinematic measures (contact locations and magnitude of excursion) for each condyle.Introduction
Methods
Wearable sensors have enabled objective functional data collection from patients before total knee replacement (TKR) and at clinical follow-ups post-surgery whereas traditional evaluation has solely relied on self-reported subjective measures. The timed-up-and-go (TUG) test has been used to evaluate function but is commonly measured using only total completion time, which does not assess joint function or test completion strategy. The current work employs machine learning techniques to distinguish patient groups based on derived functional metrics from the TUG test and expose clinically important functional parameters that are predictive of patient recovery. Patients scheduled for TKR (n=70) were recruited and instrumented with a wearable sensor system while performing three TUG test trials. Remaining study patients (n=68) also completed three TUG trials at their 2, 6, and 13-week follow-ups. Many patients (n=36) have also participated up to their 26-week appointment. Custom developed software was used to segment recorded tests into sub-activities and extract 54 functional metrics to evaluate op/non-operative knee function. All preoperative TUG samples and their standardized metrics were clustered into two unlabelled groups using the k-means algorithm. Both groups were tracked forward to see how their early functional parameters translated to functional improvement at their three-month assessment. Test total completion time was used to estimate overall functional improvement and to relate findings to existing literature. Patients that completed their 26-week tests were tracked further to their most recent timepoint.Objective
Methods
Despite improvements in the survivorship of total knee replacements (TKR) over the years, patient satisfaction following TKR has not improved, with approximately 20% of patients recording dissatisfaction with their new knee joint. It is unclear why many patients feel this way, but it may relate in part to implant designs that do not provide a “natural” feeling knee. Implant manufacturers continue to introduce new concepts for implant design, which are essential for reaching the goal of a “normal” knee after TKR surgery. The Journey II TKR (Smith & Nephew) was developed with this goal in mind. Its anatomical design attempts to mimic the normal knee joint structure to return more natural kinematics to the joint, with emphasis on eliminating both paradoxical anterior motion and reduced posterior femoral rollback. Our objective is to examine patients receiving the Journey II TKR to measure the knee joint contact kinematics of the Journey II TKR compared to a non-anatomically designed implant by the same manufacturer. We hypothesize that the Journey II TKR will have more natural contact kinematics that differ from the non-anatomically designed implant. A total of 28 individuals were recruited to receive a Journey II TKR, matching an existing prior cohort with a non-anatomical design from the same manufacturer (Legion TKR, Smith & Nephew). For both groups, a series of radiostereometric analysis (RSA) images were acquired at different knee flexion angles, ranging in 20° increments from 0° to 120°. Model-based RSA software (RSACore, Leiden, Netherlands) was used to obtain the 3D positions and orientations of the femoral and tibial implant components, which were in turn used to obtain kinematic measures (contact locations and magnitude of excursion) for each condyle. Results from the Journey II TKR group at 3 months post-operation were compared to the 2-year post-operative measurements from the Legion TKR group.Introduction
Methods
