The iASSIST system is a portable,
Introduction. Diagnosis of osteoarthritis relies primarily on image-based analyses. X-ray, CT, and MRI can be used to evaluate various features associated with OA including joint space narrowing, deformity, articular cartilage integrity, and other joint parameters. While effective, these exams are costly, may expose the patient to ionizing radiation, and are often conducted under passive, non-weightbearing conditions. A supplemental form of analysis utilizing vibroarthrographic (VAG) signals provides an alternative that is safer and more cost-effective for the patient. The objective of this study is to correlate the kinematic patterns of normal, diseased (pre-operative), and implanted (post-operative) hip subjects to their VAG signals that were collected and to more specifically, determine if a correlation exists between femoral head center displacement and vibration signal features. Methods. Of the 28 hips that were evaluated, 10 were normal, 10 were diseased, and 8 were implanted. To collect the VAG signal from each subject, two uniaxial
Introduction. In cementless THA the incidence of intraoperative fracture has been reported to be as high 28% [1]. To mitigate these surgical complications, investigators have explored vibro-acoustic techniques for identifying fracture [2–5]. These methods, however, must be simple, efficient, and robust as well as integrate with workflow and sterility. Early work suggests an energy-based method using inexpensive sensors can detect fracture and appears robust to variability in striking conditions [4–5]. The orthopaedic community is also considering powered impaction as another way to minimize the risk of fracture [6– 8], yet the authors are unaware of attempts to provide sensor feedback perhaps due to challenges from the noise and vibrations generated during powered impaction. Therefore, this study tests the hypothesis that vibration frequency analysis from an
Measurements of shoulder kinematics during activities of daily living (ADL) can be used to evaluate patient function before and after treatment and help define device testing conditions. However, due to the difficulties of making 3D motion measurements outside of laboratory conditions, there are few reports of measured shoulder 3D kinematics during ADL. The purpose of this study was to demonstrate the feasibility of using wearable inertial measurement units (IMUs) to track shoulder joint angles. A nonrandom sample of 5 subjects with normal shoulders was selected based on occupation. The occupations were: dental hygienist, primary school teacher, mechanical project engineer, administrative assistant, and retail associate. Subjects wore two OPAL IMUs (APDM, Portland OR) as shown in Figure 1 on the sternum and on the upper arm for approximately 4 hours while at their workplace performing their normal work place activities and then up to 4 hours while off-work. Orientation angles from IMUs have traditionally been estimated by integrating gyroscope data and calculating inclination angles relative to gravity with
PROBLEM. Since the COVID-19 pandemic of 2020, there has been a marked rise in the use of telemedicine to evaluate patients following total knee arthroplasty (TKA). Telemedicine is helpful to maintain patient contact, but it cannot provide objective functional TKA data. External monitoring devices can be used, but in the past have had mixed results due to patient compliance and data continuity, particularly for monitoring over numerous years. This novel stem is a translational product with an embedded sensor that can remotely monitor patient activity following TKA. SOLUTION. The Canturio™ TE∗ System (Canary Medical) functions structurally as a tibial extension for the Persona® cemented tibial plate (Zimmer Biomet). The stem is instrumented with internal motion sensors (3-D
INTRODUCTION. Total Knee Arthroplasty (TKA) is a durable procedure which allows most patients to achieve a satisfactory functional level, but there can be instability under stressful conditions. Instability is one cause of early revision, often due to misalignment or inadequate ligament balancing. Persistent instability may cause elevated polyethylene wear. Lower levels of instability may cause patient discomfort with certain stressful activities. Hence quantifying instability may have an important role in the functional evaluation of TKA. Several previous studies showed that
Introduction. Numerous factors have been hypothesized as contributing to mechanically-assisted corrosion at the head-neck junction of total hip prostheses. While variables attributable to the implant and the patient are amenable to investigation, parameters describing assembly of the component parts can be difficult to determine. Nonetheless, increasing evidence suggests that the manner of intraoperative assembly of modular components plays a critical role in the fretting and corrosion of modular implants. This study was undertaken to measure the magnitude and direction of the impaction forces applied by surgeons in assembling modular head-neck junctions under operative conditions where both the access and visibility of the prosthesis may potentially compromise component fixation. Methods. A surrogate consisting of the lower limb with overlying soft tissue was developed to simulate THR performed via a 10cm incision using the posterior approach. The surrogate was modified to match the resistance of the body to retraction of the incision, mobilization of the femur and hammering of the implanted femoral component. An instrumented femoral stem (SL PLUS) was surgically implanted into the bone after attachment of 3 miniature
Objective. Emergence of low-cost wearable systems has permitted extended data collection for unsupervised subject monitoring. Recognizing individual activities performed during these sessions gives context to recorded data and is an important first step towards automated motion analysis. Convolutional neural networks (CNNs) have been used with great success to detect patterns of pixels in images for object detection and recognition in many different applications. This work proposes a novel image encoding scheme to create images from time-series activity data and uses CNNs to accurately classify 13 daily activities performed by instrumented subjects. Methods. Twenty healthy subjects were instrumented with a previously developed wearable sensor system consisting of four inertial sensors mounted above and below each knee. Each subject performed eight static and five dynamic activities: standing, sitting in a chair/cross-legged, kneeling on left/right/both knees, squatting, laying, walking/running, biking and ascending/descending stairs. Data from each sensor were synchronized, windowed, and encoded as images using a novel encoding scheme. Two CNNs were designed and trained to classify the encoded images of both static and dynamic activities separately. Network performance was evaluated using twenty iterations of a leave-one-out validation process where a single subject was left out for test data to estimate performance on future unseen subjects. Results. Using 19 subjects for training and a single subject left out for testing per iteration, the average accuracy observed when classifying the eight static activities was 98.0% ±2.9%. Accuracy dropped to 89.3% ±10.6% when classifying all dynamic activities using a separate model with the same evaluation process. Ascending/descending stairs, walking/running, and sitting on a chair/squatting were most commonly misclassified. Conclusions. Previous related work on activity recognition using
Acetabular implant position is important for the stability, function, and long-term wear properties of a total hip arthroplasty (THA). Prior studies of acetabular implant positioning have demonstrated a high percentage of outliers, even in experienced hip surgeons, when conventional instruments are used. Computer navigation is an attractive tool for use in (THA, as it has been shown to improve the precision of acetabular component placement and reduce the incidence of outliers. However, computer navigation with imageless, large-console systems is costly and often interrupts the surgeon's workflow, and thus, has not been widely adopted. Another method to improve acetabular component positioning during THA is the use of fluoroscopy with the direct anterior approach. Studies have demonstrated that the supine position of the patient during surgery facilitates the use of fluoroscopic guidance, thus improving acetabular component position. A handheld,
Fifteen-year survivorships studies demonstrate that total knee replacements have excellent survivorship, with reports of 85 to 97%. However, excellent survivorship does not equate to excellent patient reported outcomes. Total knee imbalance with either too tight or loose soft tissues account for up to 54% of revisions in one series. This may account for many of the 20% unsatisfactory total knee arthroplasty outcomes. Soft tissue balancing technique is more like an art. The surgeon relies on subjective feel for appropriate ligamentous tension. Surgical experience and case volume play a major role in each surgeon's relative skill in balancing the knee properly. New technology of “smart trials” with embedded microelectronics and
Introduction. In Total Hip Arthroplasty (THA), proper bone preparation technique is fundamental to preventing intraoperative fracture. Anecdotally, surgeons suggest they can avoid fracture by listening for changes in the pitch of a mallet strike during broaching. Consequently, it is not surprising that researchers have explored vibroacoustic methods to prevent [1] and identify bone fractures [2, 3]. For instance, a shift in frequency of the acoustic signals during impaction has been correlated with initial stability [4, 5]. In-spite of these research-based successes, we are unaware of an intraoperative application for THA. We submit that idiosyncratic variability during impaction [6] may overwhelm analytical techniques developed in a controlled laboratory environment. The purpose of this test, therefore, was to evaluate the effect of several strike parameters on the vibro-acoustic response during impaction. Specifically, we hypothesized that the angle, location, and force of impaction would produce ‘false-positives’ in frequency regions that have been used to identify fracture [7]. Methods. A Sawbones femur (SKU1121, Medium) was prepared and broached using standard surgical technique for the Summit hip system (DePuy Synthes) progressing from size 0 to 4. The size 4 broach was firmly seated and impacted ten times (n=10) for each of the prescribed conditions (Table 1) while securely holding the femur by hand. Vibroacoustic data from an
Anterior knee pain is one of the most frequently reported musculoskeletal complaints in all age groups. However, patient's complaints are often nonspecific, leading to difficulty in properly diagnosing the condition. One of the causes of pain is the degeneration of the articular cartilage. As the cartilage deteriorates, its ability to distribute the joint reaction forces decreases and the stresses may exceed the pain threshold. Unfortunately, the assessment of the cartilage condition is often limited to a detailed interview with the patient, careful physical examination and x-ray imaging. The X-ray screening may reveal bone degeneration, but does not carry sufficient information of the soft tissues' conditions. More advanced imaging tools such as MRI or CT are available, but these are expensive, time consuming and are only suitable for detection of advanced arthritis. Arthroscopic surgery is often the only reliable option, however due to its semi-invasive nature, it cannot be considered as a practical diagnostic tool. However, as the articular cartilage degenerates, the surfaces become rougher, they produce higher vibrations than smooth surfaces due to higher friction during the interaction. Therefore, it was proposed to detect vibrations non-invasively using
Fifteen-year survivorship studies demonstrate that total knee replacements have excellent survivorship, with reports of 85 to 97%. However, excellent survivorship does not equate to excellent patient reported outcomes. Noble et al. reported that 14% of their patients were dissatisfied with their outcome with more than half expressing problems with routine activities of daily living. There is also a difference in the patient's subjective assessment of outcome and the surgeon's objective assessment. Dickstein et al. reported that a third of total knee patients were dissatisfied, even though the surgeons felt that their results were excellent. Most of the patients who report lower outcome scores do so because their expectations are not being fulfilled by the total knee replacement surgery. Perhaps this dissatisfaction is a result of subtle soft tissue imbalance that we have difficulty in assessing intra-operatively and post-operatively. Soft tissue balancing techniques still rely on subjective feel for appropriate ligamentous tension by the surgeon. Surgical experience and case volume play a major role in each surgeon's relative skill in balancing the knee properly. New technology of “smart trials” with embedded microelectronics and
Acetabular implant position is important for the stability, function, and long-term wear properties of a total hip arthroplasty (THA). Prior studies of acetabular implant positioning have demonstrated a high percentage of outliers, even for experienced hip surgeons, when conventional instruments are used. Computer navigation is an attractive tool for use in THA, as it has been shown to improve the precision of acetabular component placement and reduce the incidence of outliers. However, computer navigation with imageless, large-console systems is costly and often interrupts the surgeon's workflow, and thus has not been widely adopted. Another method to improve acetabular component positioning during THA is the use of fluoroscopy with the direct anterior approach. Studies have demonstrated that the supine position of the patient during surgery facilitates the use of fluoroscopic guidance, thus improving acetabular component position. A handheld,
Fifteen-year survivorship studies demonstrate that total knee replacements have excellent survivorship, with reports of 85% to 97%. However, excellent survivorship does not equate to excellent patient reported outcomes. Noble et al. reported that 14% of their patients were dissatisfied with their outcome with more than half expressing problems with routine activities of daily living. There is also a difference in the patient's subjective assessment of outcome and the surgeon's objective assessment. Dickstein et al. reported that a third of total knee patients were dissatisfied, even though the surgeons felt that their results were excellent. Most of the patients who report lower outcome scores due so because their expectations are not being fulfilled by the total knee replacement surgery. Perhaps this dissatisfaction is a result of subtle soft tissue imbalance that we have difficulty in assessing intra-operatively and post-operatively. Soft tissue balancing techniques still rely on subjective feel for appropriate ligamentous tension by the surgeon. Surgical experience and case volume play a major role in each surgeon's relative skill in balancing the knee properly. New technology of “smart trials” with embedded microelectronics and
Introduction. Aseptic acetabular component failure rates have been reported to be similar or even slightly higher than femoral component failure. Obtaining proper initial stability by press fitting the cementless acetabular cup into an undersized cavity is crucial to allow for secondary osseous integration. However, finding the insertion endpoint that corresponds to an optimal initial stability is challenging. This in vitro study presents an alternative method that allows tracking the insertion progress of acetabular implants in a non-destructive, real-time manner. Materials and Methods. A simplified acetabular bone model was used for a series of insertion experiments. The bone model consisted of polyurethane solid foam blocks (Sawbones #1522-04 and #1522-05) into which a hemispherical cavity and cylindrical wall, representing the acetabular rim, were machined using a computer numerically controlled (CNC) milling machine (Haas Automation Inc., Oxnard, CA, USA). Fig. 1 depicts the bone model and setup used. A total of 10 insertions were carried out, 5 on a low density block, 5 on a high density block. The acetabular cups were press fitted into the bone models by succeeding hammer hits. The acceleration of the implant-insertor combination was measured using 2 shock
Increasing data is emerging, consistently demonstrating a more rapid recovery for patients undergoing direct anterior approach (DAA) surgery. In one study, objective findings of early recovery including timed up and go tests, Functional Independence Measures are significantly faster in the first 2 weeks, and normalise by 6 weeks. A more recent randomised study shows a quicker achievement of the functional milestones of discontinuing walking aids, discontinuing opioids, stair ascent, and walking 6 blocks, as well as
Fifteen-year survivorship studies demonstrate that total knee replacement have excellent survivorship, with reports of 85 to 97%. However, excellent survivorship does not equate to excellent patient reported outcomes. Noble et al. reported that 14% of their patients were dissatisfied with their outcome with more than half expressing problems with routine activities of daily living. There is also a difference in the patient's subjective assessment of outcome and the surgeon's objective assessment. Dickstein et al. reported that a third of total knee patients were dissatisfied, even though the surgeons felt that their results were excellent. Most of the patients who report lower outcome scores due so because their expectations are not being fulfilled by the total knee replacement surgery. Perhaps this dissatisfaction is a result of subtle soft tissue imbalance that we have difficulty in assessing intraoperatively and postoperatively. Soft tissue balancing techniques still rely on subjective feel for appropriate ligamentous tension by the surgeon. Surgical experience and case volume play a major role in each surgeon's relative skill in balancing the knee properly. New technology of “smart trials” with embedded microelectronics and
Computer navigation is an attractive tool for use in total knee arthroplasty (TKA), as it is well known that alignment is important for the proper function of a total knee replacement. Malalignment of the prosthetic joint can lead to abnormal kinematics, unbalanced soft-tissues, and early loosening. Although there are no long term studies proving the clinical benefits of computer navigation in TKA, studies have shown that varus alignment of the tibial component is a risk factor for early loosening. A handheld,