Total or Partial Knee Arthroplasty Trial - TOPKAT : study protocol for a randomised controlled trial

Peer reviewedPublisher PD

A custom-made guide-wire positioning device for Hip Surface Replacement Arthroplasty: description and first results

<p>Abstract</p> <p>Background</p> <p>Hip surface replacement arthroplasty (SRA) can be an alternative for total hip arthroplasty. The short and long-term outcome of hip surface replacement arthroplasty mainly relies on the optimal size and position of the femoral component. This can be defined before surgery with pre-operative templating. Reproducing the optimal, templated femoral implant position during surgery relies on guide wire positioning devices in combination with visual inspection and experience of the surgeon. Another method of transferring the templated position into surgery is by navigation or Computer Assisted Surgery (CAS). Though CAS is documented to increase accurate placement particularly in case of normal hip anatomy, it requires bulky equipment that is not readily available in each centre.</p> <p>Methods</p> <p>A custom made neck jig device is presented as well as the results of a pilot study.</p> <p>The device is produced based on data pre-operatively acquired with CT-scan. The position of the guide wire is chosen as the anatomical axis of the femoral neck. Adjustments to the design of the jig are made based on the orthopedic surgeon's recommendations for the drill direction. The SRA jig is designed as a slightly more-than-hemispherical cage to fit the anterior part of the femoral head. The cage is connected to an anterior neck support. Four knifes are attached on the central arch of the cage. A drill guide cylinder is attached to the cage, thus allowing guide wire positioning as pre-operatively planned.</p> <p>Custom made devices were tested in 5 patients scheduled for total hip arthroplasty. The orthopedic surgeons reported the practical aspects of the use of the neck-jig device. The retrieved femoral heads were analyzed to assess the achieved drill place in mm deviation from the predefined location and orientation compared to the predefined orientation.</p> <p>Results</p> <p>The orthopedic surgeons rated the passive stability, full contact with neck portion of the jig and knife contact with femoral head, positive. There were no guide failures. The jig unique position and the number of steps required to put the guide in place were rated 1, while the complexity to put the guide into place was rated 1-2. In all five cases the guide wire was accurately positioned. Maximum angular deviation was 2.9° and maximum distance between insertion points was 2.1 mm.</p> <p>Conclusions</p> <p>Pilot testing of a custom made jig for use during SRA indicated that the device was (1) successfully applied and user friendly and (2) allowed for accurate guide wire placement according to the preoperative plan.</p

Development and Implementation of a Computational Modeling Tool for Evaluation of THA Component Position

The human body is a complicated structure with muscles, ligaments, bones, and joints. Modeling human body with computational tools are becoming a trend [1]. More importantly, using computational tools to evaluate human body is a non-invasive technique that could help surgeons and researchers evaluate implant products [2]. Therefore, the development of a model which can analyze both implant sizing suggestion and kinematics of subject specific data could prove valuable. For total hip arthroplasty, one common complication is in vivo separation and dislocation of the femoral head within the acetabular cup [3] [4]. Developing a successful computational tool to address this issue includes developing a dynamic model of hip joint, implementing implant sizing suggestion algorithms and computing component alignments. Due to advancement in technology, the current focus has been to develop patient-specific solutions, a combined program of both hip model and implant suggestion model has been developed. In this dissertation, the primary objective is to develop a fully functional hip analysis software that not only can suggestion and template the implant sizing and position, but the software can also utilize the patient specific data to run simulation with different activities. The second objective of this dissertation is to conduct hip analysis studies using hip analysis software. Overall, the results in this dissertation discuss the effect of different stem positions and surgeon preferences on the outcome of the Total Hip Arthroplasty

In vivo knee contact force prediction using patient-specific musculoskeletal geometry in a segment-based computational model

Segment-based musculoskeletal models allow the prediction of muscle, ligament, and joint forces without making assumptions regarding joint degrees-of-freedom (DOF). The dataset published for the “Grand Challenge Competition to Predict in vivo Knee Loads” provides directly measured tibiofemoral contact forces for activities of daily living (ADL). For the Sixth Grand Challenge Competition to Predict in vivo Knee Loads, blinded results for “smooth” and “bouncy” gait trials were predicted using a customized patient-specific musculoskeletal model. For an unblinded comparison, the following modifications were made to improve the predictions: further customizations, including modifications to the knee center of rotation; reductions to the maximum allowable muscle forces to represent known loss of strength in knee arthroplasty patients; and a kinematic constraint to the hip joint to address the sensitivity of the segment-based approach to motion tracking artifact. For validation, the improved model was applied to normal gait, squat, and sit-to-stand for three subjects. Comparisons of the predictions with measured contact forces showed that segment-based musculoskeletal models using patient-specific input data can estimate tibiofemoral contact forces with root mean square errors (RMSEs) of 0.48–0.65 times body weight (BW) for normal gait trials. Comparisons between measured and predicted tibiofemoral contact forces yielded an average coefficient of determination of 0.81 and RMSEs of 0.46–1.01 times BW for squatting and 0.70–0.99 times BW for sit-to-stand tasks. This is comparable to the best validations in the literature using alternative models.</jats:p

Revision Total Knee Arthroplasty using a Novel 3D Printed Titanium Augment: A Cadaveric Biomechanical Study

During revision total knee arthroplasty (rTKA), proximal tibial bone loss is frequently encountered and can result in a less-stable bone-implant fixation. A 3D printed titanium augment that conforms to the irregular shape of the proximal tibia was recently developed. The purpose of this study was to evaluate the fixation stability of rTKA with this augment in comparison to conventional cemented rTKA. Fixation stability testing was conducted on eleven pairs of thawed fresh-frozen cadaveric tibias (22 tibias) after primary and revision TKA. During the loading protocol, the bone-implant micromotion was measured using a high-resolution optical system. There was significantly less micromotion in the experimental rTKA in comparison to the standard fully cemented rTKA (p= 0.04). The novel 3D printed titanium augment offers better fixation in rTKA that would be sufficient for bony ingrowth of the augment in vivo

The effect of pathological shoulder rhythm on muscle and joint forces after reverse shoulder arthroplasty, a numerical analysis.

BACKGROUND Compromised abduction ability after reverse shoulder arthroplasty is primarily linked to limited glenohumeral range of motion while scapulothoracic mobility can typically be maintained. Glenohumeral joint forces strongly depend on the resulting scapulohumeral rhythm, however, an association between the acting muscle and joint forces and the subject-specific scapulohumeral rhythm after reverse shoulder arthroplasty has not been established. METHODS Eleven reverse shoulder arthroplasty patients were divided into groups of poor and excellent abduction ability. Subject-specific models were developed and scaled for each patient using existing motion capture data in AnyBody™. Shoulder muscle and joint forces were obtained using inverse dynamics calculations during shoulder abduction to 100° in the scapula plane. The scapulohumeral rhythm, the resting abduction angle and internal body forces between the outcome groups were compared using a Mann Whitney U test. FINDINGS The mean glenohumeral and scapulothoracic contribution to overall shoulder abduction for the excellent group was on average 9.7% higher and 21.4% lower, respectively, compared to the mean of the poor group. For shoulder abduction angles between 30° and 60°, the excellent group demonstrated on average 25% higher muscle forces in the anterior deltoid which was significantly higher compared to the poor outcome patients. Scapulothoracic muscle activity did not differ significantly between the two functional groups. INTERPRETATION Accordingly, rehabilitation strategies focusing on strengthening the anterior part of the deltoid in particular may improve clinical outcomes

Predictive Modeling of Hip Dislocation: Assessment of Surgical and Patient Factors to Reduce the Occurrence of Hip Instability and Adverse Clinical Outcomes

Instability and dislocation remain leading indications for revision of primary Total Hip Arthroplasty (THA). Many studies have addressed the links between implant design and propensity for dislocation, however a comprehensive review of the ability of modern THA constructs to protect against joint instability is needed. Accordingly, the objective of this study is to provide objective data about THA risks to be considered in the treatment algorithm to protect against adverse joint loading conditions and joint instability. Adverse loading conditions were assessed in a population of activities of daily living using data from telemetric hip implant representation in an FE simulation which included probabilistic representation of clinical implant position variation. Separately, dislocation was assessed using a series of strength-calibrated joint contact and muscle forces for a variety of THA implant designs in subject-specific musculoskeletal models of patients performing activities consistent with posterior and anterior THA dislocation. The resistive moment at the point of dislocation, as well as the overall dislocation rate per construct, provide relevant measures of resistance of the THA construct to dislocation. Based on a range of acetabular implant alignments reported clinically, variation in cup anteversion/retroversion had the largest impact on liner peak loading location of any degree of freedom throughout the prescribed activities. Cup inclination also showed a relationship to response liner loading; stem variation in either longitudinal plane was not strongly correlated to edge loading propensity across activities. Increased cup anteversion and inclination reduced the occurrence of posterior hip dislocation (82% vs 48% for anteversion and 86% vs 34% for inclination with neutral liners), however increased the occurrence of anterior hip dislocation (13% vs 94% and 39% vs 70%). Increased hip abduction and internal rotation reduced the occurrence of dislocation during posterior activities (79% vs 43% and 76% vs 50% for neutral liners respectively), but increase the occurrence of dislocation in anterior dislocation activities (45% vs 69% and 46% vs 67% for neutral liners respectively). Use of a lipped liner did increase the resistive moment at posterior dislocation, by an average of 5.2 Nm, and the flexion angle at dislocation by 1.4 degrees compared to a neutral liner. There was a reduction of similar magnitude in resistance to anterior dislocation. In each instance, a lipped liner with a posterior-inferior lip position reduced the occurrence of posterior dislocation, but increased the occurrence of anterior dislocation. Considering implant geometry, head offset had a large impact on the resulting resistive moment of the THA construct, with a sensitivity of approximately 3.8 Nm/mm of additional offset. Increasing head diameter increased resistive moment from 21 Nm to 27 Nm, a sensitivity of 0.75 Nm/mm of head diameter. Three lipped liners were considered with increasing jump distance (JD), which is a linear measure of distance a head must translate to dislocate. These designs corresponded to 23 Nm, 25 Nm, and 31 Nm resistive moments, respectively, a sensitivity of approximately 2.8 Nm/mm of additional jump distance. A dual-mobility acetabular design resulted in a resistive moment of 30 Nm. Tradeoffs between acetabular component position, design, and patient activity and the relative clinical risk of adverse implant loading as well as anterior and posterior dislocation must be considered and weighted accordingly. A quantitative understanding of tradeoffs in the dislocation risk inherent to THA construct options is valuable in supporting surgical decision making. Computer modeling provides a framework for meaningful design assessments which can be transferred and have meaningful input to clinical practice

Probabilistic Musculoskeletal Simulation Methods to Address Intersegmental Dependencies of the Knee, Hip, and Spine

Orthropaedic clinical practice in the area of the knee, hip, and spine has benefited from the concept of regional interdependence, where interventions applied to one region can influence the outcome and function of other regions of the body that may be seemingly unrelated to the applied intervention. An understanding of the biomechanical mechanisms that describe clinical practice involving knee, hip, and spine regional interdependence can improve treatment of a wide range of pathological conditions. Improvement in this area can be particularly impactful on the outcomes of patients with total joint replacement, where pathology and compensatory strategies develop during multi-joint interactions. Additionally, probabilistic methods are well suited to address knee, hip, and spine regional interdependence by using input distributions to quantify the impact of variability on the range of possible output variables. Outputs from probabilistic methods include variable interaction effects and provides sensitivity information, resulting in a more comprehensive evaluation of a system The main objectives of the work presented in this dissertation were to further our understanding of the interdependencies of the knee, hip, and spine with probabilistic musculoskeletal modeling. These objectives were achieved by developing a probabilistic plugin for use in OpenSim and performing investigations of the regional interdependence of the knee, hip, and spine involving patients with total joint replacement. An initial study identified how uncertainty in musculoskeletal simulation inputs can propagate through the stages of analysis and impact interpretation of outputs from a simulation of gait. Second, improvements to current modeling methodology for patients with total hip arthroplasty were made through the implementation of patient-specific strength scaling and input uncertainty assessment. The third study then applied these methods in an investigation of knee, hip, and spine regional interdependence in rehabilitation of patients with total hip arthroplasty to quantify the influence of simulated strengthening of hip musculature on the dynamic and mechanical interdependencies of the knee, hip and spine. A final study demonstrated how population-based musculoskeletal modeling can further impact the study of knee, hip, and spine regional interdependence by presenting the feasibility study of performing population-based musculoskeletal modeling. These studies include several novel methods for investigating the regional interdependencies of the knee, hip, and spine that have been used to translate outputs from musculoskeletal simulations into rehabilitation practice

Musculoskeletal Models in a Clinical Perspective

This book includes a selection of papers showing the potential of the dynamic modelling approach to treat problems related to the musculoskeletal system. The state-of-the-art is presented in a review article and in a perspective paper, and several examples of application in different clinical problems are provided