Introduction. Optimized tibial tray rotation during a total knee replacement (TKR) is critical for tibiofemoral congruency through full range of motion, as it affects soft tissue tension, stability and patellar tracking. Surgeons commonly reference the tibial tubercle, or the “floating tibial tray,” while testing the knee in flexion and extension. Utilization of embedded sensors may enable the surgeon to more accurately assess tibiofemoral contact points during surgery. Methods. The malrotation of the tibiofemoral congruency when utilizing the mid to medial 1/3 of the tibial tubercle for tibial rotation was evaluated in 50 posterior cruciate ligament-retaining TKRs performed by an experienced, high-volume surgeon. Sensors were embedded in the tibial trials; the rotation of the tibial tray was defined, and the femoral contact points in each compartment were captured. The surgical procedure was performed to size and then appropriately rotate the tibial tray. The anterior medial tray was pinned to control anterior-posterior and medio-lateral displacement, and allow internal and external rotation of the tray. With the capsule closed and patella reduced, the knee was reduced with trial implants. The femoral contact points and medial-lateral soft tissue tension were documented. Patellar tracking and changes in soft tissue tension were also documented. Results. In 60% (n = 30/50) of cases, further external rotation (average 5 degrees) was required. No further rotation was required in 10% (n = 5/50), and 30% (n = 15/50) required further internal rotation for optimized congruency. Patellar tracking and changes in soft tissue tension based on rotation showed parallel center of load in medio-lateral compartments and equalized intercompartment pressures resulting in optimized balance of the knee. Conclusions. Utilizing the tibial tubercle for optimized tibial tray rotation and femoral congruency was only adequate in 10% of cases. The use of sensors to define the femoral contact points on the tibia enabled the surgeon to adjust the tibial tray to optimize tibiofemoral congruency. Mal-rotated trays negatively affected soft tissue tension and patellar tracking

Patient-reported outcome measures (PROMs) have failed to highlight differences in function or outcome when comparing knee replacement designs and implantation techniques. Ankle-worn inertial measurement units (IMUs) can be used to remotely measure and monitor the bi-lateral impact load of patients, augmenting traditional PROMs with objective data. The aim of this study was to compare IMU-based impact loads with PROMs in patients who had undergone conventional total knee arthroplasty (TKA), unicompartmental knee arthroplasty (UKA), and robotic-assisted TKA (RA-TKA).

77 patients undergoing primary knee arthroplasty (29 RA-TKA, 37 TKA, and 11 UKA) for osteoarthritis were prospectively enrolled. Remote patient monitoring was performed pre-operatively, then weekly from post-operative weeks two to six using ankle-worn IMUs and PROMs. IMU-based outcomes included: cumulative impact load, bone stimulus, and impact load asymmetry. PROMs scores included: Oxford Knee Score (OKS), EuroQol Five-dimension with EuroQol visual analogue scale, and the Forgotten Joint Score.

On average, patients showed improved impact load asymmetry by 67% (p=0.001), bone stimulus by 41% (p<0.001), and cumulative impact load by 121% (p=0.035) between post-operative week two and six. Differences in IMU-based outcomes were observed in the initial six weeks post-operatively between surgical procedures. The mean change scores for OKS were 7.5 (RA-TKA), 11.4 (TKA), and 11.2 (UKA) over the early post-operative period (p=0.144). Improvements in OKS were consistent with IMU outcomes in the RA-TKA group, however, conventional TKA and UKA groups did not reflect the same trend in improvement as OKS, demonstrating a functional decline.

Our data illustrate that PROMs do not necessarily align with patient function, with some patients reporting good PROMs, yet show a decline in cumulative impact load or load asymmetry. These data also provide evidence for a difference in the functional outcome of TKA and UKA patients that might be overlooked by using PROMs alone.

Introduction

Wearable sensors are promising tools for fast clinical gait evaluations in individuals with osteoarthritis (OA) of the knee and hip. However, gait assessments with wearable sensor are often limited to relatively simple straight-ahead walking paradigms. Parameters reflecting more complex and relevant aspects of gait, including dual-tasking, turning, and compensatory upper body motion are often overlooked in literature. The aim of this study was to investigate turning, dual-task performance, and upper body motion in individuals with knee or hip OA in addition to spatiotemporal gait parameters, taking shared covariance between gait parameters into account.

Participation in a physical therapy program is considered one of the greatest predictors for successful conservative management of common shoulder disorders, however, adherence to standard exercise protocols is often poor (around 50%) and typically worse for unsupervised home exercise programs. Currently, there are limited tools available for objective measurement of adherence and performance of shoulder rehabilitation in the home setting. The goal of this study was to develop and evaluate the potential for performing home shoulder physiotherapy monitoring using a commercial smartwatch. We hypothesize that shoulder physiotherapy exercises can be classified by analyzing the temporal sequence of inertial sensor outputs from a smartwatch worn on the extremity performing the exercise.

Twenty healthy adult subjects with no prior shoulder disorders performed seven exercises from a standard evidence-based rotator cuff physiotherapy protocol: pendulum, abduction, forward elevation, internal/external rotation and trapezius extension with a resistance band, and a weighted bent-over row. Each participant performed 20 repetitions of each exercise bilaterally under the supervision of an orthopaedic surgeon, while 6-axis inertial sensor data was collected at 50 Hz from an Apple Watch. Using the scikit-learn and keras platforms, four supervised learning algorithms were trained to classify the exercises: k-nearest neighbour (k-NN), random forest (RF), support vector machine classifier (SVC), and a deep convolutional recurrent neural network (CRNN). Algorithm performance was evaluated using 5-fold cross-validation stratified first temporally and then by subject.

Categorical classification accuracy was above 94% for all algorithms on the temporally stratified cross validation, with the best performance achieved by the CRNN algorithm (99.4± 0.2%). The subject stratified cross validation, which evaluated classifier performance on unseen subjects, yielded lower accuracies scores again with CRNN performing best (88.9 ± 1.6%).

This proof-of concept study demonstrates the feasibility of a smartwatch device and machine learning approach to more easily monitor and assess the at-home adherence of shoulder physiotherapy exercise protocols. Future work will focus on translation of this technology to the clinical setting and evaluating exercise classification in shoulder disorder populations.

Objectives

Implant loosening is the most common reason for revision of total or partial knee replacement, but the patient complains of pain-not a loose implant. It would be a useful diagnostic tool to interrogate the implant to ascertain whether it remains well fixed or not, thus either confirming or eliminating this mode of failure. For such technology to be adopted by manufacturers, it must be extremely low cost and simple to build into an implant. We aim to develop a sensor that meets these requirements and, when embedded in an implant, can provide information on its fixation to the underlying bone. We have previously proven that, through impedance analysis of passive piezoelectric sensors, it is possible for such sensors to determine the cured state of cement with good correlation (0.7) to a surgeon's judgement (Darton et al, 2014). In this study we now look at how the impedance trances of the sensors can be interpreted to distinguish between tibial trays that are securely cemented in sawbone blocks and those with no cement in loose fitting sawbone blocks.

Introduction & Aims

The traditional method of soft-tissue balancing during TKA is subjective in nature, and stiffness and instability are common indications for revision, suggesting that TKA balancing by subjective assessment is suboptimal. This study examines the intraoperative mediolateral loads measured with a nanosensor-enabled tibial insert trial and the sequential balancing steps used to achieve quantitative balance. Data obtained from a prospective multicenter study was assessed to determine the effect of targeted ligament release on intra-articular loading, and to understand which types of releases are necessary to achieve quantified ligament balance.

Smart instrumentation targets optimal joint hardware installation. Intelligent implants target the chronic assessment of joint health and hardware condition.

Intelligent implants would facilitate the collection of data, closing the loop to drive best surgical practice, joint system design, and the improvement of outcomes. Intelligent devices could assist post-op in managing pain and promoting recovery. Intelligent implants could offer opportunity for early detection and less invasive intervention should problems arise acutely, or even long after implant.

While the development of smart instrumentation is tactically important, the development of intelligent implants is vital to the improvement of outcomes, and should be central to the strategic vision for orthopedic technology development.

One out of every five total knee arthroplasty (TKA) recipients is unhappy with the outcome of their surgery. As the number of TKA candidates continues to increase, so, too, will the dissatisfied patient population. These statistics should not be acceptable to the surgeons, hospitals, and patients implicated in this elective procedure. There are many contributing factors to patient dissatisfaction, paramount among them being post-operative levels of functionality and pain. Therefore, in an attempt to increase function and decrease pain levels through soft-tissue management, sensor-assisted TKA outcomes were compared with manual TKA outcomes.

One hundred and fourteen primary TKA patients were evaluated: 57 sensor-assisted TKA patients; 57 manual TKA patients. All procedures were performed by the same surgeon. In order to reduce confounding variables, all patients were matched for: age, gender distribution, BMI, marital status, smoking proclivity, pre-operative ROM, pre-operative alignment, and employment status. Outcomes scores were captured pre-operatively, and at the 6-month interval, including Knee Society Score metrics and the Oxford score, as well as 6-month ROM. The sensor device used in this analysis is inserted into the tibial component, during the trialing, and displays loading values in the medial and lateral compartments (lbf.), and also displays the medial and lateral center of load location. In the sensor-assisted TKA group, balance was achieved for all patients, as previously described in literature.

There was a statistically significant rate of improvement, for all outcomes measures, in the sensor-assisted TKA group when compared with the manual group (Figure 1). In addition to rate of improvement, there was also a significant trend towards a significance in ROM in the sensor-assisted group, as a stand-alone dependent variable (P = 0.002).

By the 6-month follow-up interval, patients in receipt of a sensor-assisted TKA reported greater improvement in function and less pain than the patients in the manual TKA group. This data suggests that soft-tissue balance may contribute to faster recovery, as reported by the patient. Because pain and function play an integral role in patient satisfaction, further follow-up might yield higher satisfaction in the sensor-assisted patient group, which is consistent with previously published observations.

Introduction

Computer-assisted methods for acetabulum cup navigation have shown to be able to improve the accuracy of the procedure, but are time-consuming and difficult to use. The goal of this project was to develop an easy-to-use navigation technique, requiring minimal equipment for acetabular cup alignment.

INTRODUCTION

Achieving balance in TKA is critical in assuring favorable outcomes. But, in order to achieve quantifiably balanced loading values, is it more advantageous to make bony corrections or release soft-tissue? The answer to this question will be paramount in evaluating the most appropriate surgical techniques for use with new dynamic technology, thereby maximizing favorable clinical outcomes. Therefore, the purpose of this investigation was to evaluate a possible quantitative loading threshold, using intraoperative sensors, which may dictate surgical correction of bone versus soft-tissue release.

Introduction

Post-operative clinical outcomes of TKA are dependent on a multitude of surgical and patient-specific factors. Malrotation of the femoral and/or tibial component is associated with pain, accelerated wear of the tibial insert, joint instability, and unfavorable patellar tracking and dislocation. Using the transepicondylar axis to guide implantation of the femoral component is considered to be an accurate anatomical reference and is widely used. However, no gold standard currently exists with respect to ensuring optimal rotation of the tibial tray. Literature has suggested that implantation methods, which reference the tibial tubercle, reduce positioning outliers with more consistency than other anatomical landmarks. Therefore, the purpose of this evaluation is to use data collected from intraoperative sensors to assess the true rotational accuracy of using the mid-medial third of the tibial tubercle in 98 TKAs.

Introduction

Proper soft-tissue balance is important for achieving favorable clinical outcomes following TKA, as ligament imbalance can lead to pain, stiffness or instability, accelerated polyethylene wear, and premature failure of implants. Until recently, soft-tissue balancing was accomplished by subjective surgeon feel and by use of static spacer blocks. Now, nanonsensor-embedded implant trials allow surgeons to quantify peak load and center of load in the medial and lateral compartments during the procedure, and to adjust ligament tension and implant positioning accordingly. The purpose of this 3-year, multicenter study is to evaluate 500 patients who have received primary TKA with the use of intraoperative sensors in order to correlate quantified ligament balance to clinical outcomes.

Hip instability is one of the most common causes for total hip arthroplasty (THA) revision surgery. Studies have indicated that lumbar fusion (LF) surgery is a risk factor for hip dislocation. Instrumented spine fusion surgery decreases pelvic tilt, which might lead to an increase in hip motion to accommodate this postural change. To the best of our knowledge, spine-pelvis-hip kinematics during a dynamic activity in patients that previously had both a THA and LF have not been investigated. Furthermore, patients with a combined THA and LF tend to have greater disability. The purpose was to examine spine-pelvis-hip kinematics during a sit to stand task in patients that have had both THA and LF surgeries and compare it to a group of patients that had a THA with no history of spine surgery. The secondary purpose was to compare pain, physical function, and disability between these patients. This cross-sectional study recruited participants that had a combined THA and LF (n=10; 6 females, mean age 73 y) or had a THA only (n=11; 6 females, mean age 72 y). Spine, pelvis, and hip angles were measured using a TrakSTAR motion capture system sampled at 200 Hz. Sensors were mounted over the lateral thighs, base of the sacrum, and the spinous process of the third lumbar,12th thoracic, and ninth thoracic vertebrae. Participants completed 10 trials of a standardized sit-to-stand-to-sit task. Hip, pelvis, lower lumbar, upper lumbar, and lower thoracic sagittal joint angle range of motion (ROM) were calculated over the entire task. In addition, pain, physical function, and disability were measured with clinical outcomes: Hip Disability Osteoarthritis Outcome Score (pain and physical function), Oswestry Low Back Disability Questionnaire (disability), and Harris Hip Score (pain, physical function, motion). Physical function performance was measured using 6-Minute Walk Test, Stair Climb Test, and 30s Chair Test. Angle ROMs during the sit-to-stand-to-sit task and clinical outcomes were compared between THA+LF and THA groups using independent t-tests and effect sizes (d). The difference in hip ROM was approaching statistical significance (p=0.07). Specifically, the THA+LF group had less hip ROM during the sit-to-stand-to-sit task than the THA only group (mean difference=11.17, 95% confidence interval=-1.13 to 23.47), which represented a large effect size (d=0.83). There were no differences in ROM for pelvis (p=0.54, d=0.28) or spinal (p=0.14 to 0.97; d=0.02 to 0.65) angles between groups. The THA+LF group had worse clinical outcomes for all measures of pain, physical function, and disability (p=0.01 to 0.06), representing large effect sizes (d=0.89 to 2.70). Hip ROM was not greater in the THA+LF group, and thus this is unlikely a risk factor for hip dislocation during this specific sit-to-stand-to-sit task. Other functional tasks that demand greater excursions in the joints should be investigated. Furthermore, the lack of differences in spinal and pelvis ROM were likely due to the task and the THA+LF group had spinal fusions at different levels. Combined THA+LF results in worse clinical outcomes and additional rehabilitation is required for these patients

Introduction. The rate of technological innovation in procedural total knee arthroplasty has left little time for critical evaluation of a new technology before the adoption of even newer modalities. With more drastic financial restrictions being placed on operating room spending, orthopaedic surgeons are now required to provide excellent results on a budget. It is integral that both clinical efficacy and cost-effectiveness of these intraoperative technologies be fully understood in order to provide patients with effectual, economically conscious care. The purpose of this qualitative analysis of literature was to evaluate clinical and economic efficacy of the three most prominent technologies currently used in TKA: computer navigation, patient-specific instrumentation, and kinetic sensors. Methods. Three hundred and ninety one publications were collected; 100 were included in final qualitative analysis. Criteria for inclusion in the analysis was defined only insofar as that each piece assessed one of the above listed aspects of the three technologies Literature included in the final evaluation contained background information on each respective technology, clinical outcomes, revision rates, and/or cost analyses. All comparisons were conducted in a strictly qualitative manner, and no attempts were made to conduct interstudy statistical analyses due to the high level of variability in methodology and data collected. Results. Navigation. Navigation was designed to reduce alignment and component positioning outliers. Many surgeons have argued that its results are no better than that achieved by manual techniques. Some studies have shown that clinical outcomes have improved in navigated TKA patients, but an abundance of research suggests that this is not the case. In consideration of the expense of this technology, coupled with inconclusive results, navigation does not, at this time, seem to fit the schema for significantly reducing the rate of revision and operative cost. PSI. Patient-specific instrumentation was designed to reduce the expense of navigation systems, simplify computer-assisted methods, and improve functional outcomes. However, a majority of research has suggested that PSI is either no better, or even worse, at alignment accuracy than manual techniques. Very few publications have been able to attest to any significant increase in functional outcomes scores of PSI patients, over the scores of navigation or manual TKA. Kinetic Sensors. Kinetic sensor technology has been engineered to quantify soft-tissue balance, improve rotational alignment, and decrease the risk of post-operative complications. Albeit a young device, the sparse literature that exists shows promising results. The margin of error for detecting loads has been shown to be low, the sensors have successfully measured subtle imbalance that leads to altered gait kinematics, and has shown significant improvement in several patient-reported outcomes measures in balanced patients. Discussion. This review shows that not all modalities are created equal, and demonstrates that the cost of some technologies may not yield a clinical or time-saving payoff for the patient and hospital. While kinetic sensor devices seem to be the most promising modality, more research will be necessary to confirm its advantages over time. But, great care must be taken when adopting any novel technology; “new” does not always mean “improved”

Introduction. Biomechanists have been trying to obtain integrated and accurate human motion data. However, it is not so easy, because some have limitation of accuracy, some have limitation of the observation area, and some are expensive. For example, motion capturing can obtain whole body motion data, but needs space, is expensive, but only surface motion could be obtained. So is not so sensitive for the bone rotation. Sensors of pressure, acceleration, and so forth are less expensive and less hard to use, but the data are limited. 2D–3D shape matching such as Jointtrack can describe bone motion including rotation, but the detectable area is limited by the size of flat panel fluoroscopy. In this study, we have combined multiple joint motion analysis by Jointtrack and reconstructed full lower extremities' motion. Method. Pelvis, bilateral femurs, and bilateral tibiae geometries were obtained from CAT scan using Mimics®. Gait motion fluoroscopy was done on a treadmill around hip joints and knee joints (Fig.1). On each heal thin film switch was attached and connected to electrically driven metal flag which can be recorded in fluoroscopic images on heal strikes. Images of five gait cycles were taken with 15Hz and every image was sorted by the percentage of gait cycle, and then processed by Jointtrack. Centre of femoral head of observing side was defined as our origin. Using treadmill, the walking direction could be uniquely defined. From the femoral 3D displacement and rotation, knee position can be calculated. The same procedures were done for the knee assessment, mutual coordinate of hip centre from the knee can be calculated. All of them are sorted by the percentage of the gait cycle too. Combining data from hip and knee, complete lower extremities' motion could be described. Regression analyses of x, y, z coordinates of femurs from hip and from knee were done to evaluate the accuracy. Motion capture of floor gait and treadmill gait were done to evaluate the difference. (Fig.2). Materials. Five arthritic hip patients and one normal control were assessed in hip and knee by Jointtrack. Normal Control was assessed by motion capture too. Results. The motions of lower extremities were descrobbed as the translations of coordinates of hip, knee, and ankle joints (Fig.3). The coefficients of determination were calculated for each patient. Except for one patient, good regression was obtained between hip assessment and knee assessment. In motion capture, the difference of the gait speed on the floor and on the treadmill effected to the gait pattern. Discussion. Motion capture can assess multiple joint motions in natural state, but they are only skin motion. Jointtrack can deprive 3D translation and rotation data of the bones, but the object is limited to single joint and is unnatural in traveling direction. Our method can enlarge its object to multiple joints. Getting more data, we hope we can analyze bone motions including rotations and resultant force etc. more accurately and more practically