Effect of Corrective Surgery on Lower Limb Mechanics in Patients with Crouch Gait

Crouch gait a progressively degrading gait deviation associated with the neurological disorder cerebral palsy. If left untreated it can lead to anterior knee pain and a loss of ambulation. At present there exists no agreed upon metric for determining the surgical procedures used to treat crouch gait and there is insufficient means to analytically compare the results of different procedures. The aims of this thesis work were to create a pipeline to transform a patient’s gait analysis data into a finite element model, develop a model of sufficient complexity to evaluate a range of outcomes by which to judge the efficacy of a surgical procedure, analyze the change between pre- and post-operative models and the changes between models with different surgical procedures, and to quantify the impact of varying different surgical parameters. A generic lower limb rigid body musculoskeletal model was developed and used in conjunction with patient-specific static and dynamic motion capture to create scaling factors and joint kinematics, respectively. The musculoskeletal model was scaled and converted into a finite element model. This lower torso model was integrated with a detailed finite element model of the knee joint including patella, femur and tibia heads, associated articular cartilage, patellofemoral ligaments, patellar tendon, and quadriceps tendons. This type of combined finite element model was created for each patient, pre- and post-operatively, for a series of patient’s treated for crouch gait at Children’s Hospital Colorado. Each model was modified to replicate the surgical procedure(s) that each individual patient underwent. Comparison between pre- and post-operative models show significant improvement in tibiofemoral flexion-extension and patellar articular cartilage stress in post-operative models. In order to assess the effect of surgical parameters on muscle efficiency, the finite element model was modified such that tibiofemoral flexion-extension was controlled by adaptive muscle forces calculated using a proportional-integral feedback control system. The feedback system adjusted quadriceps and hamstrings forces to try and meet a target flexion profile. A feedback control model was created for three patients; subsequently, each model was modified to run multiple simulations with modified surgical procedures and parameters. The models were modified to include distal femoral extension osteotomy procedures of 0º, 15º, or 30º, or patella tendon advancement procedures with 0 cm, 1 cm, or 2 cm shortening. The muscle forces needed to reach the target kinematics were compared. Further simulations are required to identify clear links between surgical decisions and patient-specific parameters, but the developed model shows promise for future studies both for crouch gait and other musculoskeletal pathologies

Influence of minimalist footwear on knee and ankle loads during the squash lunge

Squash is associated with a high incidence of knee and ankle joint injuries. The aim of this work was to examine the effects of squash specific, running shoes and minimalist footwear on knee and ankle loads during the lunge movement in squash players. Twelve male squash players performed lunge movements whilst wearing squash specific, running shoes and minimalist footwear. The loads experienced by the knee and ankle joints were calculated. Patellofemoral forces were significantly greater in running shoes (5.10 B.W) compared to minimalist footwear (4.29 B.W). Achille tendon forces were significantly larger in the minimalist footwear (3.10 B.W) compared to the running shoes (2.64 B.W) and squash specific footwear (2.88 B.W). This shows that whilst minimalist footwear may reduce the incidence of knee pathologies in squash players corresponding increases in ankle loading may induce an injury risk at this joint

A Description of the Movement of the Canine Pelvic Limb in Three Dimensions Using an Inverse Dynamics Method, and a Comparison of Two Techniques to Surgically Repair a Cranial Cruciate Ligament Deficient Stifle

The purposes of the dissertation were: 1) to describe three-dimensional (3D) motion of the canine pelvic limb using an inverse dynamics method, and 2) to compare these motion patterns between normal, healthy dogs and those that have had their stifles stabilized by one of two surgical methods approximately five years earlier. Twenty-five dogs were allocated to three groups; healthy control dogs, dogs that had received the tibial plateau leveling osteotomy (TPLO), and dogs that had received the lateral fabellar suture (LFS) stabilization technique. Both surgical techniques were performed approximately five years prior on stifles with surgically induced cranial cruciate ligament (CCL) rupture. A kinematic model was created so that virtual markers could be used to describe the pelvic limb motion in 3D. Kinetic, kinematic, and morphometric data were integrated so that an inverse dynamics method could be used to describe angular displacement, joint moment and power across the hock, stifle, and hip joints in the sagittal, frontal, and transverse planes. Discrete points and shapes of waveforms were analyzed for any differences among groups. Motion and energy patterns were successfully determined in 3D for all three joints of the canine pelvic limb. There was similarity between all three groups for all variables studied in the three planes with the exception of two variables. In the sagittal plane, the TPLO group had a more extended hip at the beginning of stance phase compared to the control group. Also, in the frontal plane, the LFS group had a significantly larger maximum power across the stifle when compared to the normal group. Despite the differences between these two variables, there were no differences in gait patterns between these groups that would suggest that one surgical procedure is superior to the other. Both surgical groups moved similarly to the healthy control group. The method of collecting kinematic data in this study allowed for the description of motion of the canine pelvic limb in 3D using inverse dynamics. Comparison between normal controls and dogs that had two different methods of repair for stifle instability showed similar gait patterns for all three groups

Valutazione cinematica intraoperatoria con utilizzo del navigatore e postoperatoria con rsa dinamica nelle protesi totali di ginocchio

Restoring a correct implant kinematics and providing a good ligament balance and patellar tracking is mandatory to improve clinical and functional outcome after a Total Knee Replacement. Surgical navigation systems are a reliable and accurate tool to help the surgeon in achieving these goals. The aim of the present study was to use navigation system with an intra-operative surgical protocol to evaluate and determine an optimal implant kinematics during a Total Knee Replacement

Kinematic and kinetic effects of knee and ankle sagittal plane joint restrictions during squatting

"The purpose of this study was to evaluate compensatory biomechanical patterns in the lower extremity created by restricted knee flexion and ankle dorsiflexion when performing squats. Forty two healthy subjects (21 men, 21 women; 22.5 (4.5) years, 73.8 (17.8) kg, 167.5 (12.5) cm) participated in the study. Data were collected using a force plate and a 3-d electromagnetic tracking device for bilateral lower extremity analyses. Three parallel squats were performed in non braced, right knee restricted and right ankle restricted conditions. Dependent measures were hip, knee and ankle total joint displacement and work done on the hip, knee and ankle during the eccentric portion of the squat. Three repeated measures ANOVAs compared lower extremity kinematics between conditions, while one repeated measure ANOVAs evaluated lower extremity kinetics. Mean hip, knee and ankle ROM was reported, as was sagittal plane work done on the hip, knee and ankle for each condition and limb. The primary findings of this study indicate hip and ankle flexion displacement significantly decreased in the contralateral (non-braced) limb during the ankle joint restricted condition. Ipsilateral (braced) limb hip, knee and ankle flexion significantly decreased during the knee restricted condition, while ipsilateral knee and ankle flexion decreased during the ankle restricted condition. Lower extremity sagittal plane energetic changes occurred in the ipsilateral knee and ankle when the knee joint was restricted and at the ipsilateral ankle in the ankle restricted condition. Relative and absolute shifts in work done on the hip, knee and ankle when compared to the non braced squat were observed. This study may best serve as a general sagittal plane model for clinicians and coaches to reference when using the parallel squat in patients/athletes with knee and ankle dysfunction. This has practical significance to clinicians as these substitutions in work could result in overuse (secondary) injury to the compensatory site or insufficient loading to the dysfunctional site, rendering it weak and susceptible to additional primary injury or limiting the athletes maximal performance. "--Abstract from author supplied metadata

Bayesian parameter estimation of ligament properties based on tibio-femoral kinematics during squatting

The objective of this study is to estimate the, probably correlated, ligament material properties and attachment sites in a highly non-linear, musculoskeletal knee model based on kinematic data of a knee rig experiment for seven specific specimens. Bayesian parameter estimation is used to account for uncertainty in the limited experimental data by optimization of a high dimensional input parameter space (50 parameters) consistent with all probable solutions. The set of solutions accounts for physiologically relevant ligament strain (ϵ&lt;6%). The transitional Markov Chain Monte Carlo algorithm was used. Alterations to the algorithm were introduced in order to avoid premature convergence. To perform the parameter estimation with feasible computational cost, a surrogate model of the knee model was trained. Results show that there is a large intra- and inter-specimen variability in ligament properties, and that multiple sets of ligament properties fit the experimentally measured tibio-femoral kinematics. Although all parameters were allowed to vary significantly, large interdependence is only found between the reference strain and attachment sites. The large variation between specimens and interdependence between reference strain and attachment sites within one specimen, show the inability to identify a small range of ligament properties representative for the patient population. To limit ligament properties uncertainty in clinical applications, research will need to invest in establishing patient-specific uncertainty ranges and/or accurate in vivo measuring methods of the attachment sites and reference strain and/or alternative (combinations of) movements that would allow identifying a unique solution.</p

DOES SYMMETRY OF LOWER LIMB KINETICS EXIST IN SITTING AND STANDING TASKS?

This study compared sit-to-stand and stand-to-sit symmetry for total hip arthroplasty patients (n=40) and a control group (n=19). 3D kinematics and kinetics were recorded. A symmetry index was calculated for kinetics. T-tests were significant for hip and knee moments and powers, and extension sum of moments for sit-to-stand, and for hip extension moment and power for stand-to-sit. THA patients mainly rely on their nonoperated limb to perform the sit-to-stand task. There was less asymmetry during the stand-to-sit tasks, were found significant. This study underlines the presence of asymmetrical kinetics in THA patient for these tasks, and demonstrated that sit-to-stand is more sensitive to asymmetry. These results should be considered in rehabilitation programs, and consequently allow these patients to return to a more active lifestyle

Influence of a knee brace intervention on perceived pain and patellofemoral loading in recreational athletes

Background: The current investigation aimed to investigate the effects of an intervention using knee bracing on pain symptoms and patellofemoral loading in male and female recreational athletes. Methods: Twenty participants (11 males & 9 females) with patellofemoral pain were provided with a knee brace which they wore for a period of 2 weeks. Lower extremity kinematics and patellofemoral loading were obtained during three sport specific tasks, jog, cut and single leg hop. In addition their self-reported knee pain scoreswere examined using the Knee injury and Osteoarthritis Outcome Score. Datawere collected before and after wearing the knee brace for 2 weeks. Findings: Significant reductions were found in the run and cut movements for peak patellofemoral force/pressure and in all movements for the peak knee abduction moment when wearing the brace. Significant improvements were also shown for Knee injury and Osteoarthritis Outcome Score subscale symptoms (pre: male= 70.27, female = 73.22 & post: male = 85.64, female = 82.44), pain (pre: male = 72.36, female = 78.89 & post: male = 85.73, female = 84.20), sport (pre: male = 60.18, female = 59.33 & post: male = 80.91, female =79.11), function and daily living (pre: male = 82.18, female = 86.00 & post: male = 88.91, female = 90.00) and quality of life (pre: male= 51.27, female= 54.89 & post: male= 69.36, female= 66.89). Interpretation:Male and female recreational athleteswho suffer frompatellofemoral pain can be advised to utilise knee bracing as a conservative method to reduce pain symptoms

Applied Machine Learning for Classification of Musculoskeletal Inference using Neural Networks and Component Analysis

Artificial Intelligence (AI) is acquiring more recognition than ever by researchers and machine learning practitioners. AI has found significance in many applications like biomedical research for cancer diagnosis using image analysis, pharmaceutical research, and, diagnosis and prognosis of diseases based on knowledge about patients\u27 previous conditions. Due to the increased computational power of modern computers implementing AI, there has been an increase in the feasibility of performing more complex research. Within the field of orthopedic biomechanics, this research considers complex time-series dataset of the sit-to-stand motion of 48 Total Hip Arthroplasty (THA) patients that was collected by the Human Dynamics Laboratory at the University of Denver. The research focuses on predicting the motion quality of the THA patients by analyzing the loads acting on muscles and joints during one motion cycle. We have classified the motion quality into two classes: Fair and Poor , based on muscle forces, and have predicted the motion quality using joint angles. We address different types of Machine Learning techniques: Artificial Neural Networks (LSTM - long short-term memory, CNN - convolutional neural network, and merged CNN-LSTM) and data science approach (principal component analysis and parallel factor analysis), that utilize remodeled datasets: heatmaps and 3-dimensional vectors. These techniques have been demonstrated efficient for the classification and prediction of the motion quality. The research proposes time-based optimization by predicting the motion quality at an initial stage of musculoskeletal model simulation, thereby, saving time and efforts required to perform multiple model simulations to generate a complete musculoskeletal modeling dataset. The research has provided efficient techniques for modeling neural networks and predicting post-operative musculoskeletal inference. We observed the accuracy of 83.33% for the prediction of the motion quality under the merged LSTM and CNN network, and autoencoder followed by feedforward neural network. The research work not only helps in realizing AI as an important tool for biomedical research but also introduces various techniques that can be utilized and incorporated by engineers and AI practitioners while working on a multi-variate time-series wide shaped data set with high variance