Integrating wearables and modelling for monitoring rehabilitation following total knee joint replacement.

BACKGROUND AND OBJECTIVE: Wearable inertial devices integrated with modelling and cloud computing have been widely adopted in the sports sector, however, their use in the health and medical field has yet to be fully realised. To date, there have been no reported studies concerning the use of wearables as a surrogate tool to monitor knee joint loading during recovery following a total knee joint replacement. The objective of this study is to firstly evaluate if peak tibial acceleration from wearables during gait is a good surrogate metric for computer modelling predicted functional knee loading; and secondly evaluate if traditional clinical patient related outcomes measures are consistent with wearable predictions. METHODS: Following ethical approval, four healthy participants were used to establish the relationship between computer modelling predicted knee joint loading and wearable measured tibial acceleration. Following this, ten patients who had total knee joint replacements were then followed during their 6-week rehabilitation. Gait analysis, wearable acceleration, computer models of knee joint loading, and patient related outcomes measures including the Oxford knee score and range of motion were recorded. RESULTS: A linear correlation (R2 of 0.7-0.97) was observed between peak tibial acceleration (from wearables) and musculoskeletal model predicted knee joint loading during gait in healthy participants first. Whilst patient related outcome measures (Oxford knee score and patient range of motion) were observed to improve consistently during rehabilitation, this was not consistent with all patient's tibial acceleration. Only those patients that exhibited increasing peak tibial acceleration over 6-weeks rehabilitation were positively correlated with the Oxford knee score (R2 of 0.51 to 0.97). Wearable predicted tibial acceleration revealed three patients with a consistent knee loading, five patients with improving knee loading, and two patients with declining knee loading during recovery. Hence, 20% of patients did not present with satisfactory joint loading following total knee joint replacement and this was not detected with current patient related outcome measures. CONCLUSIONS: The use of inertial measurement units or wearables in this study provided additional insight into patients who were not exhibiting functional improvements in joint loading, and offers clinicians an 'off-site' early warning metric to identify potential complications during recovery and provide the opportunity for early intervention. This study has important implications for improving patient outcomes, equity, and for those who live in rural regions.

Automated creation and tuning of personalised muscle paths for OpenSim musculoskeletal models of the knee joint.

Computational modelling is an invaluable tool for investigating features of human locomotion and motor control which cannot be measured except through invasive techniques. Recent research has focussed on creating personalised musculoskeletal models using population-based morphing or directly from medical imaging. Although progress has been made, robust definition of two critical model parameters remains challenging: (1) complete tibiofemoral (TF) and patellofemoral (PF) joint motions, and (2) muscle tendon unit (MTU) pathways and kinematics (i.e. lengths and moment arms). The aim of this study was to develop an automated framework, using population-based morphing approaches to create personalised musculoskeletal models, consisting of personalised bone geometries, TF and PF joint mechanisms, and MTU pathways and kinematics. Informed from medical imaging, personalised rigid body TF and PF joint mechanisms were created. Using atlas- and optimisation-based methods, personalised MTU pathways and kinematics were created with the aim of preventing MTU penetration into bones and achieving smooth MTU kinematics that follow patterns from existing literature. This framework was integrated into the Musculoskeletal Atlas Project Client software package to create and optimise models for 6 participants with incrementally increasing levels of personalisation with the aim of improving MTU kinematics and pathways. Three comparisons were made: (1) non-optimised (Model 1) and optimised models (Model 3) with generic joint mechanisms; (2) non-optimised (Model 2) and optimised models (Model 4) with personalised joint mechanisms; and (3) both optimised models (Model 3 and 4). Following optimisation, improvements were consistently shown in pattern similarity to cadaveric data in comparison (1) and (2). For comparison (3), a number of comparisons showed no significant difference between the two compared models. Importantly, optimisation did not produce statistically significantly worse results in any case.

Machine learning methods to support personalized neuromusculoskeletal modelling.

Many biomedical, orthopaedic, and industrial applications are emerging that will benefit from personalized neuromusculoskeletal models. Applications include refined diagnostics, prediction of treatment trajectories for neuromusculoskeletal diseases, in silico design, development, and testing of medical implants, and human-machine interfaces to support assistive technologies. This review proposes how physics-based simulation, combined with machine learning approaches from big data, can be used to develop high-fidelity personalized representations of the human neuromusculoskeletal system. The core neuromusculoskeletal model features requiring personalization are identified, and big data/machine learning approaches for implementation are presented together with recommendations for further research.

Rapid muscle volume prediction using anthropometric measurements and population-derived statistical models.

Knowledge of subject-specific muscle volumes may be used as surrogates for evaluating muscle strength and power generated by 'fat-free' muscle mass. This study presents population-based statistical learning approaches for predicting 'fat-free' muscle volume from known anthropometric measurements. Using computed tomography (CT) imaging data to obtain lower-limb muscle volumes from 50 men and women, this study evaluated six statistical learning methods for predicting muscle volumes from anthropometric measurements: (i) stepwise regression, (ii) linear support vector machine (SVM), (iii) 2nd-order polynomial SVM, (iv) linear partial least squares regression (PLSR), (v) quadratic PLSR, and (vi) 3rd-order spline fit PLSR. These techniques have successfully been demonstrated in bioengineering applications and freely available in open-source toolkits. Analysis revealed that separating a general population into sexes and/or cohorts based on adipose level may improve prediction accuracies. The most important measures that statistically influence muscle volume predictions were shank girth, followed by sex and finally leg length, as identified using stepwise regression. SVM learning predicted muscle volume with an accuracy of 85 ± 4% when using linear interpolation, but performed poorly with an accuracy of 59 ± 6% using polynomial interpolation. The simpler linear PLSR exhibited muscle volume prediction accuracy of 87 ± 2%, while quadratic PLSR was slightly reduced at 82 ± 3%. For the spline fit PLSR, high accuracy was observed on the training data set (~ 99%) but over-fitting (a drawback of high-interpolation methods) resulted in erroneous predictions on testing data, and hence, the model was deemed unsuitable. In conclusion, use of linear PLSR models with variables of sex, leg length, and shank girth is a useful tool for predicting 'fat-free' muscle volume.

Relationship between lower lumbar spine shape and patient bone metabolic activity as characterised by 18F NaF bio-markers.

Chronic lower lumbar pain has been associated with elevated bone metabolic activity in the spine. Diagnosis of bone metabolic activity is currently through integrating Positron Emission Tomography (PET) with Sodium Fluoride (18F-NaF) biomarkers. It has been reported that numerous observable pathologies including lumbar fusion, disc abnormalities and scoliosis have often been associated with increased 18F-NaF uptake. The aim of this study was to identify what features of lower lumbar shape most strongly correlate with 18F-NaF uptake. Following a principal component analysis of 23 patients who presented with lumbar pain and underwent 18F-NaF PET-CT, it was revealed that three modes interpreted as (i) sacral tilt, (ii) vertebral disc spacing and (iii) spine size were the three characteristics that described 88.7% of spine shape in our study population. 18F-NaF was described by two modes including 18F-NaF intensity and spatial variation (anterior-inferior to posterior-superior). 18F-NaF was most sensitive to sacral tilt followed by vertebral disc spacing. A predictive model derived from that spine population was able to predict 18F-NaF 'hot-spot' locations with 85 ±â€¯5% accuracy and with 71 ±â€¯3% accuracy for the 18F-NaF magnitude. These results suggest that patients reporting with lower lumbar pain and who present with increased sacral tilt profiles and/or reduced disc spacing are good candidates for further 18F-NaF PET-CT imaging, evidenced by the high association between those shape profiles and 18F-NaF uptake.

Early morphologic changes in trapeziometacarpal joint bones with osteoarthritis.

OBJECTIVE: Characterising the morphological differences between healthy and early osteoarthritic (EOA) trapeziometacarpal (TMC) joints is important for understanding osteoarthritis onset, and early detection is important for treatment and disease management. This study has two aims: first, to characterise morphological differences between healthy and EOA TMC bones. The second aim was to determine the efficacy of using a statistical shape model (SSM) to detect early signs of osteoarthritis (OA). METHODS: CT image data of TMC bones from 22 asymptomatic volunteers and 47 patients with EOA were obtained from an ongoing study and used to generate a SSM. A linear discriminant analysis (LDA) classifier was trained on the principal component (PC) weights to characterise features of each group. Multivariable statistical analysis was performed on the PC to investigate morphologic differences. Leave-one-out classification was performed to evaluate the classifiers performance. RESULTS: We found that TMC bones of EOA subjects exhibited a lower aspect ratio (P = 0.042) compared with healthy subjects. The LDA classifier predicted that protrusions (up to 1.5 mm) at the volar beak of the first metacarpal were characteristic of EOA subjects. This was accompanied with widening of the articular surface, deepening of the articular surface, and protruding bone growths along the concave margin. These characteristics resulted in a leave-one-out classification accuracy of 73.9% (95% CI [61.9%, 83.8%]), sensitivity of 89.4%, specificity of 40.9%, and precision of 75.9%. CONCLUSION: Our findings indicate that morphological degeneration is well underway in the EOA TMC joint, and shows promise for a clinical tool that can detect these features automatically.

Toward modeling locomotion using electromyography-informed 3D models: application to cerebral palsy.

This position paper proposes a modeling pipeline to develop clinically relevant neuromusculoskeletal models to understand and treat complex neurological disorders. Although applicable to a variety of neurological conditions, we provide direct pipeline applicative examples in the context of cerebral palsy (CP). This paper highlights technologies in: (1) patient-specific segmental rigid body models developed from magnetic resonance imaging for use in inverse kinematics and inverse dynamics pipelines; (2) efficient population-based approaches to derive skeletal models and muscle origins/insertions that are useful for population statistics and consistent creation of continuum models; (3) continuum muscle descriptions to account for complex muscle architecture including spatially varying material properties with muscle wrapping; (4) muscle and tendon properties specific to CP; and (5) neural-based electromyography-informed methods for muscle force prediction. This represents a novel modeling pipeline that couples for the first time electromyography extracted features of disrupted neuromuscular behavior with advanced numerical methods for modeling CP-specific musculoskeletal morphology and function. The translation of such pipeline to the clinical level will provide a new class of biomarkers that objectively describe the neuromusculoskeletal determinants of pathological locomotion and complement current clinical assessment techniques, which often rely on subjective judgment. WIREs Syst Biol Med 2017, 9:e1368. doi: 10.1002/wsbm.1368 For further resources related to this article, please visit the WIREs website.

Multiscale musculoskeletal modelling, data-model fusion and electromyography-informed modelling.

This paper proposes methods and technologies that advance the state of the art for modelling the musculoskeletal system across the spatial and temporal scales; and storing these using efficient ontologies and tools. We present population-based modelling as an efficient method to rapidly generate individual morphology from only a few measurements and to learn from the ever-increasing supply of imaging data available. We present multiscale methods for continuum muscle and bone models; and efficient mechanostatistical methods, both continuum and particle-based, to bridge the scales. Finally, we examine both the importance that muscles play in bone remodelling stimuli and the latest muscle force prediction methods that use electromyography-assisted modelling techniques to compute musculoskeletal forces that best reflect the underlying neuromuscular activity. Our proposal is that, in order to have a clinically relevant virtual physiological human, (i) bone and muscle mechanics must be considered together; (ii) models should be trained on population data to permit rapid generation and use underlying principal modes that describe both muscle patterns and morphology; and (iii) these tools need to be available in an open-source repository so that the scientific community may use, personalize and contribute to the database of models.

Men and women have similarly shaped carpometacarpal joint bones.

Characterizing the morphology of the carpometacarpal (CMC) joint bones and how they vary across the population is important for understanding the functional anatomy and pathology of the thumb. The purpose of this paper was to develop a statistical shape model of the trapezium and first metacarpal bones to characterize the size and shape of the whole bones across a cohort of 50. We used this shape model to investigate the effects of sex and age on the size and shape of the CMC joint bones and the articulating surface area of the CMC joint. We hypothesized that women have similar shape trapezium and first metacarpal bones compared to men, following scaling for overall size. We also hypothesized that age would be a significant predictor variable for CMC joint bone changes. CT image data and segmented point clouds of 50 CMC bones from healthy adult men and women were obtained from an ongoing study and used to generate two statistical shape models. Statistical analysis of the principal component weights of both models was performed to investigate morphological sex and age differences. We observed sex differences, but were unable to detect any age differences. Between men and women the only difference in morphology of the trapezia and first metacarpal bones was size. These findings confirm our first hypothesis, and suggest that the women have similarly shaped trapezium and first metacarpal bones compared to men. Furthermore, our results reject our second hypothesis, indicating that age is a poor predictor of CMC joint morphology.

Child Abuse and Neglect: Screening for Risks During the Perinatal Period.

Purpose: Currently, there is a claim for earlier interventions for families in order to prevent child maltreatment. Here, a screening instrument to assess risk indicators for child abuse and neglect already in the context of maternity clinics is introduced. The present study is the first report on the psychometric properties of this instrument, the "short questionnaire for risk indices around birth" (RIAB). Material and Methods: Data were collected in the context of three different studies conducted at Ulm University Hospital. To examine interrater reliability eight case vignettes were rated by n = 90 study participants (50 students and 40 experts working at a maternity clinic). Criterion validity was examined in two studies applying the German version of the child abuse potential inventory CAPI (n = 96 families at risk and n = 160 additional families). Results: Both laymen and experts were able to understand and use the screening instrument correctly, leading to a high agreement with the sample solutions given. A high concordance was found between parents' and experts' ratings: In case of no reported risk factors applying the screening instrument RIAB, parents themselves reported significantly less stressors and burdens, compared to those parents with an indication for a thorough examination as pointed out in the RIAB. Conclusion: In the context of maternity clinics the RIAB is a useful, broadly applicable instrument, screening for existing risk factors at the earliest and thus allowing for the initiation of specific interventions when needed.

Measuring health-related quality of life in clinical trials in cystic fibrosis.

The inclusion of health-related quality of life (HRQoL) as an outcome measure in cystic fibrosis (CF) clinical trials can supply important patient-reported information not captured by other endpoints. Both an appropriate HRQoL measure and sound methodology are required in order to draw valid inferences about treatments and HRQoL. This paper provides the current consensus of the HRQoL Outcomes Group. Particular consideration has been given to the appropriateness of measurement scales, the rationale for including specific domains as endpoints, the importance of considering baseline ceiling effects and the difficulties of data interpretation. Guidance is provided on HRQoL measurement in National and European CF clinical trials.

Utilization of psychosocial care and oncological follow-up assessments among German long-term survivors of cancer with onset during adolescence.

BACKGROUND: Survivors of pediatric cancer are at increased risk for medical and psychosocial late effects. This study retrospectively investigated the utilization of oncological and psychosocial care by former adolescent cancer patients (≥ 5 years since cancer diagnosis) in Germany. PATIENTS: Based on data of the German Childhood Cancer Registry (N=1 876 survivors of cancer with an age at diagnosis between 15 and 18 years), the study cohort comprised 820 survivors of adolescent cancer (time since diagnosis: M=13.7, SD=6.0, age at follow-up: M=30.4, SD=6.0 years). METHOD: Survivors of adolescent cancer completed standardized questionnaires measuring symptoms of posttraumatic stress, depression and anxiety as well as items on their utilization of medical and psychosocial care. RESULTS: More than a quarter (26.2%) of the survivors was no longer attending regular oncological follow-up assessments. Less than half of the survivors (44.4%) had received psychosocial care, mostly during their in-patient cancer treatment and their post-acute rehabilitation phase. Out of 184 survivors showing clinically relevant symptoms of posttraumatic stress, anxiety and/or depression at time of the study, 12.0% received psychosocial care and 13.6% took psychotropic medication. CONCLUSION: It should be studied further why only a small proportion of the survivors showing clinically relevant symptoms received psychosocial or psychopharmacological treatment. Systematic oncological follow-up assessments should take psychological late effects into greater account.

The impact of an inpatient family-oriented rehabilitation program on parent-reported psychological symptoms of chronically ill children.

OBJECTIVE: To investigate the change of psychological symptoms and quality of life in children and adolescents with congenital heart disease, cancer, or cystic fibrosis after a family-oriented inpatient rehabilitation program. METHODS: 302 participants in the intervention (aged 4-17 years, mean=8.7) were assessed using standard questionnaires at admission to the rehabilitation program, at discharge, and 6 months post discharge. Parent-reported behavioral and emotional symptoms were compared to a healthy control group from the National Health Interview and Examination Survey for Children and Adolescents (n=903). RESULTS: At admission, 27.5% of patients showed abnormal levels on the total difficulties score of the Strengths and Difficulties Questionnaire - parent version (SDQ), while an additional 16.9% had slightly elevated symptoms (relative risk=2.16). Patients' psychological symptoms were negatively correlated with their quality of life (QoL) and with parental QoL. After rehabilitation, the patients' symptoms improved significantly, and the improvement persisted for 6 months in those patients who could be followed. CONCLUSIONS: The rehabilitation program can be considered a promising strategy to improve the patients' psychological adaptation.

Prediction of glycosaminoglycan content in human cartilage by age, T1ρ and T2 MRI.

OBJECTIVE: A relationship between T1ρ relaxation time and glycosaminoglycan (GAG) content has been demonstrated in chemically degraded bovine cartilage, but has not been demonstrated with quantitative biochemistry in human cartilage. A relationship has also been established between T2 relaxation time in cartilage and osteoarthritis (OA) severity. We hypothesized that T1ρ relaxation time would be associated with GAG content in human cartilage with normal T2 relaxation times. METHODS: T2 relaxation time, T1ρ relaxation time, and glycosaminoglycan as a percentage of wet weight (sGAG) were measured for top and bottom regions at 7 anatomical locations in 21 human cadaver patellae. For our analysis, T2 relaxation time was classified as normal or elevated based on a threshold defined by the mean plus one standard deviation of the T2 relaxation time for all samples. RESULTS: In the normal T2 relaxation time subset, T1ρ relaxation time correlated with sGAG content in the full-thickness and bottom regions, but only marginally in the top region alone. sGAG content decreased significantly with age in all regions. CONCLUSION: In the subset of cartilage specimens with normal T2 relaxation time, T1ρ relaxation time was inversely associated with sGAG content, as hypothesized. A predictive model, which accounts for T2 relaxation time and the effects of age, might be able to determine longitudinal trends in GAG content in the same person based on T1ρ relaxation time maps.

Impact of a family-oriented rehabilitation programme on behavioural and emotional problems in healthy siblings of chronically ill children.

OBJECTIVE: To evaluate the impact of a family-oriented inpatient rehabilitation programme on behavioural and emotional problems in healthy siblings of chronically ill children and to assess the association between these problems and quality of life. METHODS: A total of 259 healthy children (4-16 years, M = 8.6 years, SD = 3.3) with a chronically ill sibling were enrolled in the study. Parents filled in the Strengths and Difficulties Questionnaire, while the children answered a self-report quality of life instrument (LQ-KID) at the time of admission and discharge from the clinic and at a 6-month follow-up. Comparisons were performed with a matched control group from the German general population (n= 777). RESULTS: Significant behavioural or emotional symptoms were found in 30.5% of the healthy siblings, the relative risk of having elevated scores being 2.2 compared with the control group. Symptoms were inversely correlated with quality of life (r=-0.42). During the inpatient rehabilitation, symptoms decreased significantly to a normal level. Similarly, quality of life significantly improved, except in the dimension family relations. CONCLUSIONS: Family-oriented inpatient rehabilitation is a promising approach to improve the mental health of children with a chronically ill sibling.

Robotics-based synthesis of human motion.

The synthesis of human motion is a complex procedure that involves accurate reconstruction of movement sequences, modeling of musculoskeletal kinematics, dynamics and actuation, and characterization of reliable performance criteria. Many of these processes have much in common with the problems found in robotics research. Task-based methods used in robotics may be leveraged to provide novel musculoskeletal modeling methods and physiologically accurate performance predictions. In this paper, we present (i) a new method for the real-time reconstruction of human motion trajectories using direct marker tracking, (ii) a task-driven muscular effort minimization criterion and (iii) new human performance metrics for dynamic characterization of athletic skills. Dynamic motion reconstruction is achieved through the control of a simulated human model to follow the captured marker trajectories in real-time. The operational space control and real-time simulation provide human dynamics at any configuration of the performance. A new criteria of muscular effort minimization has been introduced to analyze human static postures. Extensive motion capture experiments were conducted to validate the new minimization criterion. Finally, new human performance metrics were introduced to study in details an athletic skill. These metrics include the effort expenditure and the feasible set of operational space accelerations during the performance of the skill. The dynamic characterization takes into account skeletal kinematics as well as muscle routing kinematics and force generating capacities. The developments draw upon an advanced musculoskeletal modeling platform and a task-oriented framework for the effective integration of biomechanics and robotics methods.

Muscle and external load contribution to knee joint contact loads during normal gait.

Large knee adduction moments during gait have been implicated as a mechanical factor related to the progression and severity of tibiofemoral osteoarthritis and it has been proposed that these moments increase the load on the medial compartment of the knee joint. However, this mechanism cannot be validated without taking into account the internal forces and moments generated by the muscles and ligaments, which cannot be easily measured. Previous musculoskeletal models suggest that the medial compartment of the tibiofemoral joint bears the majority of the tibiofemoral load, with the lateral compartment unloaded at times during stance. Yet these models did not utilise explicitly measured muscle activation patterns and measurements from an instrumented prosthesis which do not portray lateral compartment unloading. This paper utilised an EMG-driven model to estimate muscle forces and knee joint contact forces during healthy gait. Results indicate that while the medial compartment does bear the majority of the load during stance, muscles provide sufficient stability to counter the tendency of the external adduction moment to unload the lateral compartment. This stability was predominantly provided by the quadriceps, hamstrings, and gastrocnemii muscles, although the contribution from the tensor fascia latae was also significant. Lateral compartment unloading was not predicted by the EMG-driven model, suggesting that muscle activity patterns provide useful input to estimate muscle and joint contact forces.

Effectiveness of a family-oriented rehabilitation program on the quality of life of parents of chronically ill children.

BACKGROUND: Parents of chronically ill children face numerous burdens in daily life, which can impair their quality of life (QoL) significantly. Therefore in family-oriented rehabilitation, not only the children themselves, but also their parents receive interventions. These aim at stabilizing parents both mentally and physically to enable them to support their children in the best possible way. This study investigates the effects of an inpatient family-oriented rehabilitation program on the QoL of parents of chronically ill children. PATIENTS: A consecutive sample of 231 mothers and 155 fathers of children suffering from cancer, cardiac diseases or cystic fibrosis participated in the study. METHOD: In a prospective longitudinal study, parental QoL was repeatedly assessed using the Ulm Quality of Life Inventory for Parents (ULQIE) at three different time points: admission to the rehabilitation clinic, discharge after four weeks of inpatient treatment, and at a six-month follow-up. RESULTS: Parental QoL increased markedly during rehabilitation treatment (mothers eta (2)=.326, fathers eta (2)=.249). Moreover, six months after the intervention, parental quality of life was still markedly improved compared to baseline assessment (mothers eta (2)=.259, fathers eta (2)=.069). The child's diagnosis had no effect on the level and course of parental QoL. CONCLUSIONS: Taking part in family-oriented rehabilitation can improve the QoL of parents of children suffering from cancer, cardiac diseases or cystic fibrosis. Such programs could be expected to affect the way chronically ill children cope with their condition and this should be examined in future studies.

Evaluation of psychiatric liaison-services for adolescents in residential group homes.

OBJECTIVE: Adolescents in residential care are a high-risk population for psychiatric disorders. Due to limited access to outpatient treatment, crises often result in psychiatric hospitalizations. These crises are often accompanied by termination of supportive relationships, which increases the risk for further problems. To minimize hospitalizations and to stabilize the psychological state of these adolescents, we developed and evaluated a home-treatment intervention program based on psychiatric liaison-services and compared it to standard medical care (SMC). METHODS: The intervention was applied in 11 German residential group homes (N = 288, M = 14.1 years, SD = 2.7), while adolescents from 15 institutions (N = 336, M = 13.6 years, SD = 3.0) served as a comparison group (CG) (SMC). The frequency and duration of psychiatric inpatient treatment episodes were documented and caregiver-reported behavioural symptoms were assessed at baseline and at 6 and 12 months postintervention. RESULTS: In both groups, less than 10% of the adolescents were admitted to psychiatric wards. Compared to SMC, hospitalizations were of shorter duration in the intervention group (IG) (1.30 vs 2.47 days per head within 12 months, p < .001). In both groups, behavioural problems decreased overtime. CONCLUSIONS: Applying a home-treatment intervention program to children in residential care helps to stabilize the developmental course of this high-risk population by shortening psychiatric inpatient treatment.

The phenomenon of twisted growth: humeral torsion in dominant arms of high performance tennis players.

This manuscript is driven by the need to understand the fundamental mechanisms that cause twisted bone growth and shoulder pain in high performance tennis players. Our ultimate goal is to predict bone mass density in the humerus through computational analysis. The underlying study spans a unique four level complete analysis consisting of a high-speed video analysis, a musculoskeletal analysis, a finite element based density growth analysis and an X-ray based bone mass density analysis. For high performance tennis players, critical loads are postulated to occur during the serve. From high-speed video analyses, the serve phases of maximum external shoulder rotation and ball impact are identified as most critical loading situations for the humerus. The corresponding posts from the video analysis are reproduced with a musculoskeletal analysis tool to determine muscle attachment points, muscle force vectors and overall forces of relevant muscle groups. Collective representative muscle forces of the deltoid, latissimus dorsi, pectoralis major and triceps are then applied as external loads in a fully 3D finite element analysis. A problem specific nonlinear finite element based density analysis tool is developed to predict functional adaptation over time. The density profiles in response to the identified critical muscle forces during serve are qualitatively compared to X-ray based bone mass density analyses.