MSc, Physiotherapy, Faculty of Health Sciences, University of the Witwatersrand / Introduction Disabled sport has become very popular over the last decade with a variety of sports now available for persons with disabilities to compete in. Wheelchair basketball is a fast growing sport in South Africa. However, it is also considered a high-risk sport with most reported injuries coming from participating in the game along with tennis, road racing, rugby and soccer (Nunome et al, 2002, Ferrara and Peterson, 2000 and Curtis, 1997). The sport is characterised by high intensity propulsion and manoeuvring as well as reaching overhead for shooting, passing and rebounding (Goosey-Tolfrey et al, 2002 and Curtis et al, 1999). The athletes are thus at risk of developing in particular shoulder injuries. This study aimed to establish the prevalence of shoulder pain in South African; Gauteng based professional male wheelchair basketball players. It aimed to highlight predisposing factors contributing to the prevalence of shoulder pain as well as establish whether there is a difference in shoulder pain between the wheelchair bound athletes vs. the otherwise ambulatory athletes. By quantifying the magnitude of the problem it was hoped that awareness would lead to measures taken to rectify any problems highlighted by the research. Methods Twenty-nine professional South African: Gauteng male wheelchair basketball players took part in a cross sectional descriptive survey based study. The researcher, following signed informed consent, administered a piloted valid and reliable questionnaire to gain information regarding demographics, medical history and lifestyle habits. Results were expressed in the form of tables and graphs with frequencies, percentages and averages used to describe findings. Results Prevalence of shoulder pain was found to be 72.4% with 21 of 29 participants having experienced shoulder pain since using a wheelchair and 11 of the 29 (37.9%) having current shoulder pain. The number of years using a wheelchair significantly influenced the prevalence iv of shoulder pain (p = 0.03). One hundred percent (nine out of nine) of participants who had been using a wheelchair for longer than 10 years had experienced the problem, while of those who had been using a wheelchair for less than 10 years, 57.14% (four out of seven) had experienced shoulder pain. Time spent at work was found to be significantly associated with the presence of shoulder pain. Of the 12 people who worked more than 30 hours per week, 12 (100%) had experienced shoulder pain (p = 0.05). In the comparison of the ambulatory vs non ambulatory athletes, the wheelchair bound participants tended to be more likely to experience shoulder pain with 12 out of 15 having shoulder problems and 7 of the 12 ambulatory participants having experienced shoulder pain. This was however not a significant finding (p = 0.22). Conclusion It was found that the prevalence of shoulder pain in professional wheelchair basketball athletes in Gauteng was 72.4%. This was significantly associated with hours spent at work as well as years spent using a wheelchair. There were no significant findings regarding shoulder pain prevalence in the otherwise ambulatory vs wheelchair bound wheelchair basketball athletes. Shoulder pain is an important problem in the wheelchair basketball athlete. More education is needed regarding prevention of shoulder problems in our athletes with an emphasis on posture and ergonomic handling.

Subacromial impingement accounts for significant burdens on the economy and individual quality of life. The development and progression of this disorder is thought to be related to overuse; however, little is known regarding biomechanical factors such as scapular kinematics, shoulder muscle recruitment and joint proprioception with respect to this disorder. The high degree of variability between individuals on these biomechanical measures limits our ability to make inferences behind the development of shoulder impingement. Here, biomechanical factors associated with impingement are investigated using within-subjects designs in order to reduce this inherent variability. Using modern clinical techniques, this dissertation is applicable towards treatment of shoulder impingement as well as scientific understanding of motor control and function in the presence of pain. This dissertation includes previously published and un-published co-authored material.

Os acostamentos exercem funções importantes em uma rodovia, tanto em relação à melhoria das condições operacionais, tais como a capacidade e a segurança viárias, quanto ao desempenho dos pavimentos, protegendo a estrutura da pista principal, melhorando as condições de drenagem e de transferência de carga. Entretanto, os acostamentos têm sido suprimidos ou implantados de maneira incorreta por razões de economia. O presente trabalho reuniu critérios e recomendações existentes sobre a implantação de acostamentos no que diz respeito à sua influência na capacidade e na segurança viárias, às suas características geométricas, aos métodos para a definição do tipo, dimensionamento e sobre os defeitos encontrados nos pavimentos, tanto nos acostamentos quanto nas pistas. Também efetuou análises para mensurar a importância dos acostamentos no bom desempenho de uma rodovia, tanto em relação às condições operacionais, como do desempenho do pavimento. A partir destas análises verificou-se que a supressão de acostamentos em uma rodovia pode reduzir a sua capacidade em 7% e aumentar o índice de acidentes previstos em até 28%. Com relação ao desempenho dos pavimentos, a partir do levantamento das condições funcionais e estruturais dos pavimentos existentes na malha rodoviária pertencente à Divisão Regional DR-2 do Departamento de Estradas de Rodagem do Estado de São Paulo (DER/SP) efetuado em 2005, verificou-se que o Índice de Qualidade Final da malha composta por rodovias com acostamentos é superior ao da malha composta por rodovias sem acostamentos. Foram então realizadas análises que verificaram a influência dos acostamentos (i) na vida útil de pavimentos flexíveis e rígidos através da utilização do método de dimensionamento da AASHTO; (ii) na espessura das placas de concreto dos pavimentos rígidos através dos métodos de dimensionamento da AASHTO e da PCA; (iii) nas tensões atuantes nas placas de concreto dos pavimentos rígidos através da análise mecanicista com a utilização do programa EVERFE 2.24. Todas as análises mostraram que os acostamentos melhoram significativamente o desempenho do pavimento da pista principal, seja aumentando a sua vida útil de 100 a 400% ou reduzindo a espessura necessária do revestimento da pista principal em cerca de 25%. Realizou-se também uma análise de custo para orientar a definição do tráfego a ser considerado para o dimensionamento do pavimento dos acostamentos, onde se constatou que o valor de 5% do tráfego total considerado para a pista implica em aumento de apenas 2 a 3 % nos custos totais da pavimentação, sendo recomendável o seu uso. Por fim, propôs-se um Fluxograma para Projeto baseado nas análises realizadas e com o objetivo de orientar a decisão de implantar ou não os acostamentos, assim como fornecer recomendações a serem seguidas em ambos os casos. / Shoulders has important functions in a highway, so much in relation to the improvement of the operational conditions, such as the capacity and the road safety, as for the pavements performance, protecting the structure of the mainline, improving the drainage and load transfer conditions. However, the shoulders have been suppressed or implanted in incorrect way for economy reasons. The present work gathered criteria and existent recommendations on the implantation of shoulders related to its influence in the capacity and road safety, to their geometric characteristics, to the methods for the definition of the type, design method and failures in the pavements, in the shoulders and in the tracks. It also made analyses to measure the importance of the shoulders in the good performance of a highway, so much in relation to the operational conditions, as of the pavement performance. Starting from these analyses it was verified that the suppression of shoulders in a highway can reduce its capacity in 7% and to increase the predicted accidents index in up to 28%. Regarding the pavements performance, starting from the functional and structural conditions of the existent pavements in the road mesh belonging to the Regional Division DR-2 of the Department of Highways of the State of São Paulo (DER/SP) in 2005, it was verified that the value of Final Quality Index of the mesh composed by highways with shoulders is superior to the mesh composed by highways without shoulders. Then, analyses were made to verify the influence of the shoulders (i) in the flexible and rigid pavements life cycle through the use of the AASHTO design method; (ii) in the concrete thickness of the rigid pavements through the AASHTO and PCA design methods; (iii) in the stresses in the concrete plate of the rigid pavements through the analysis mechanic with the use of the software EVERFE 2.24. All of the analyses showed that the shoulders improve significantly the pavement performance of the mainline, increasing its life cycle from 100 to 400% or reducing the necessary thickness of the covering of the mainline in about 25%. It also took place a cost analysis to guide the definition of the traffic to be considered in the shoulders pavement design, where it was verified that the value of 5% of the total traffic considered for the mainline increases only 2 to 3% in the total costs of the paving, being advisable its use. Finally, it was proposed a Flowchart for Project based on the accomplished analyses and with the objective of guiding the decision of implanting or not the shoulders, as well as supplying recommendations to be following in both cases.

O objetivo deste estudo foi avaliar a confiabilidade intradia e interdias dos valores de amplitude da eletromiografia de superfície, dos músculos da cintura escapular e membro superior, durante a realização de 3 exercícios isométrico com a extremidade distal do segmento fixa em uma superfície estável e outra superfície instável, com descarga de peso axial controlada para o membro superior. Para tanto, 20 adultos saudáveis realizaram os exercícios push-up, bench-press e wall-press em diferentes níveis de carga (80 e 100% da carga máxima). Os valores de carga produzida por cada um dos exercícios foram registrados de maneira simultânea à eletromiografia. Os sujeitos realizaram três contrações voluntárias máximas (CVM) na posição de prova de função muscular de cada músculo, para obtenção do valor de referência para normalização dos valores de root mean square (RMS) e da integral do envoltório linear (?env). Os sujeitos foram instruídos, a realizarem de forma aleatória, 3 séries de contrações isométricas por 6 segundos em cada exercício, com intervalo de 2 minutos entre as séries e exercícios.Os sinais eletromiográficos dos músculos deltóide porção anterior e posterior, trapézio fibras superiores, serrátil anterior, peitoral maior porção clavicular, bíceps braquial porção longa e tríceps braquial porção longa foram captados por eletrodos de superfície ativos simples diferenciais, realizados em dois testes com intervalo de sete dias. Os dados foram coletados com freqüência de amostragem de 4000Hz e aplicados filtros digitais de passa baixa de 500Hz e passa alta de 20Hz. Os valores de RMS e ?env foram normalizados pelo valor máximo da amplitude eletromiográfica obtida em 1 das 3 CVM do músculo correspondente. As confiabilidades intradia e interdias foram calculadas através do coeficiente de correlação intraclasse (ICC), erro padrão da medida (SEM) e coeficiente de variação (CV). Os resultados indicaram excelente confiabilidade intradia dos valores de amplitude eletromiográfica (ICC ?0,75). A confiabilidade interdias dos valores normalizados de RMS apresentou valores variando entre bom e excelente (ICC 0,52-0,98), já os valores normalizados de ?env apresentaram valores pobres a excelente de confiabilidade (ICC 0,06-0,93). Os valores de carga produzidos durante os exercícios apresentaram excelente confiabilidade intradia e interdias (ICC ?0,97). Por fim, os resultados do presente estudo sugerem que a confiabilidade dos valores normalizados de amplitude eletromiográfica dos músculos analisados apresentam valores mais confiáveis durante os exercícios realizados com superfície estável. Já os níveis de carga empregados (80 e 100%) durante os exercícios parecem não ter influenciado nos níveis de variabilidade, talvez por serem cargas muito próximas. / The objective of the present study was to evaluate the intra and interday reliability of surface electromyography amplitude values of the scapular girdle muscles and upper limbs during the performance of 3 isometric exercises of closed kinetic chain regarding the upper limbs with the fix distal segment extremity on one stable surface and the other one on one unstable surface. In this regard, 20 healthy adults realized the exercises push-up, bench-press and wall-press with different load levels (80 and 100% maximal load). The load values produced for each exercise were recorded simultaneously to the electromyography. The individuals performed three maximal voluntary contractions (MVC) in the muscular testing position of each muscle for the obtainment of the reference value for the root mean square (RMS) normalization values and for the integrated of the linear envelope (?env). The individuals were instructed to realize at random, 3 isometric contraction series taking each exercise 6 seconds with a rest of 2 minutes between the series and the exercises. The electromyographic signals of the anterior and posterior deltoid, upper trapezius, anterior serratus, pectoralis major, biceps and triceps brachial muscle were captured by simple active differential surface electrodes, in two tests with a 7-day interval. Data were collected with a sampling frequency of 4000Hz and 500Hz low and 20Hz high passage digital filters. The RMS and ?env values were normalized by the maximal electromyographic amplitude value obtained in 1 of the 3 MVC of the corresponding muscle. The intra and interday reliabilities were calculated through the intraclass correlation coefficient (ICC), standard error measure (SEM) and coefficient of variation (CV). The results indicated an excellent intraday reliability of the electromyographic amplitude values (ICC ?0.75). The interday reliability of the RMS normalized values presented values varying between good and excellent (ICC 0.52-0.98), whereas the ?env normalized values presented poor to excellent reliability values (ICC 0.06-0.93). The load values produced during the exercises presented excellent intra and interdays reliability. Finally, the results of the present study suggest that the reliability of the electromyographic amplitude normalized values of the analyzed muscles present better values during the performance of the exercises with stable surface. However the load levels utilized during the exercises do not seem to have influenced the variability levels, eventually in view of being very close levels

Indivíduos com Síndrome do Impacto apresentam alterações nos movimentos da escápula em relação ao tórax como uma diminuição da rotação superior, inclinação posterior e aumento da rotação medial, que associada a diminuição do controle e do recrutamento da musculatura estabilizadora podem causar pinçamento dos tecidos moles. O objetivo deste estudo foi determinar o efeito de um protocolo de fortalecimento com carga e complexidade progressivas e aumento da percepção cinestésica na cinemática escapular de indivíduos com síndrome do impacto, enfatizando os músculos serrátil anterior, romboides e porções superior, média e inferior do trapézio. Vinte e cinco indivíduos com diagnóstico da síndrome foram submetidos ao programa de fortalecimento muscular e aumento do controle motor que teve duração de oito semanas, realizados três vezes por semana. O sistema eletromagnético de aquisição de dados foi utilizado para avaliar a cinemática em três planos antes e após o protocolo. A dor e a função do ombro foram avaliadas pelo Shoulder Pain and Disability Index (SPADI-Brasil). O modelo linear de efeitos mistos foi utilizado para as comparações. A escápula apresentou alterações pós-intervenção com redução da rotação interna no repouso, plano sagital e frontal, diminuição da inclinação anterior nos três planos e redução da rotação superior no plano frontal e escapular . Houve diminuição da dor e melhora da função avaliada pelo SPADI-Br. O protocolo de controle motor e fortalecimento muscular altera a cinemática da articulação escapulotorácica e gera diminuição da dor e melhora da qualidade de vida. / Patients with subacromial impingement syndrome have changes in the scapula relative to the thorax movements with decreased upward rotation, posterior tilt and increased medial rotation that if associated with control and recruitment of stabilizer muscles decrease, could result on soft tissues impingement. The aim of this study is to determine the effect of a strengthening and kinesthetic awareness protocol with progressive and complexity load in scapular kinematics of individuals with impingement syndrome, emphasizing the serratus anterior, rhomboids and upper, middle and lower trapezius. Twenty-five diagnosed patients with the syndrome did undergo to the muscle strengthening and increased motor control program during eight weeks, three times a week. The electromagnetic data acquisition system was used to evaluate the kinematic at three planes before and after the protocol. The shoulder pain and function were evaluated by Shoulder Pain and Disability Index (SPADI-Brazil). The linear mixed-effects model was used for comparisons pre- and post-intervention. The scapula showed post-intervention changes with reduced internal rotation at rest, sagittal and frontal plane, decreased anterior tilt in three planes and reducing the upward rotation on the frontal and the scapular planes, decreased pain and improvement in function assessed by SPADI-Br. The motor control and strengthening protocol changes the kinematics scapulothoracic joint and results in decreased pain and improved quality of life.

The purpose of this study was to characterize glenohumeral joint laxity and stiffness using instrumented arthrometry. To evaluate the validity of an instrumented measurement system we compared cutaneous and bone-pinned measures of laxity and stiffness that replicate previously reported in vivo methodology. Characterization of capsular laxity was achieved through determination of the sagittal plane translational area at increasing levels of quantified force. Finally, a method for increasing the objectivity of the standard manual laxity examination was developed for the orthopaedic clinician to quantify humeral head translation and capsular volume in vivo. We hypothesized that: 1) cutaneous measures could accurately predict bone-pinned measures, 2) capsular laxity would increase with increasing levels of applied force, and 3) manual cutaneous, manual bone-pinned, and force-displacement bone-pinned measures of translation would be equal. Thirty fresh frozen cadaveric shoulder specimens (mean age=70��14 years) were tested. The shoulders were thawed and mounted to a custom-made shoulder-testing apparatus. Displacement was measured using an electromagnetic tracking system. Sensors were secured cutaneously and with bone-pins to the scapula and humerus. Force-displacement testing was performed using a load applicator and manual displacement testing utilized the anterior/posterior drawer and inferior sulcus tests. A comparison of cutaneous and bone-pinned measures of laxity and stiffness revealed good to excellent criterion validity (r=0.68 to 0.79). Examination of displacement measures at increasing levels of force revealed increasing capsular laxity with symmetric directional compliance. No significant difference was observed between anterior and posterior translation (0.4 mm, p=.55), with significant differences between inferior and anterior (4.6 mm, p<.0001) and between inferior and posterior (5.1 mm, p<.0001). A comparison of manual cutaneous to bone-pinned manual and kinetic measures of translation revealed a significant difference between methods (p=.0024) and between directions (p<.0001) with no significant interaction (p=.0948). Estimations of the force required to achieve clinical end-point suggest that greater force is required in the anterior (173 N) direction compared to posterior (123 N) and inferior (121 N). We have developed two new methods to measure glenohumeral joint kinematics and reported new information regarding normal kinematics of the glenohumeral joint. / Graduation date: 2001

Shoulder pain is very common, affecting 14-21 % of the population at some time during their lifetime. The aims of this thesis were to improve the understanding of various aspects concerning the pathogenesis and treatment of subacromial pain and rotator cuff tears. Patients and healthy individuals were examined and compared in five studies: Study I) Seventy patients were retrospectively examined, clinically and with ultrasound, 15 years after arthroscopic subacromial decompression. All patients had an intact rotator cuff at surgery. Ultrasound showed significantly fewer rotator cuff tears compared to the prevalence of asymptomatic tears reported in the literature for the same age group. This indicates that arthroscopic subacromial decompression might protect the rotator cuff. Study II) Forty-two patients were retrospectively examined, clinically and with ultrasound, 39 months (mean) after an acute rotator cuff repair. All patients had pseudoparalysis after trauma, a full thickness tear and no previous history of shoulder symptoms. A delay in surgical treatment of three months and the number of tendons injured did not affect the outcome. Age affected outcome negatively. Study III) Plasma samples from 17 patients with cuff tears and 16 plasma samples from healthy age- and gender-matched controls were collected and analysed regarding the levels of matrix metalloproteinases and their inhibitors, TIMP1-4. Elevated levels of TIMP-1 were found in the patients with cuff tears compared to controls. Higher levels of TIMP-1, TIMP-3 and MMP-9 were found in patients with full-thickness tears compared to patients with partial-thickness tears. Study IV) Ninety-seven patients with longstanding subacromial pain, on the waiting-list for arthroscopic subacromial decompression, were prospectively randomised to specific shoulder exercises or control exercises for three months. Thereafter they were clinically examined and asked if they still wanted surgery. The specific shoulder exercises focusing on eccentric exercise for the rotator cuff and scapula stabilisers were found to be effective in reducing subacromial pain and improving shoulder function, thereby reducing the need for surgery. Study V) All patients including those operated, in Study IV were re-examined after one year using clinical assessment scores. The option of surgery was continuously available up to the one-year follow-up. Ultrasound and radiological examinations performed at inclusion were analysed in relation to the choice of surgery. The positive effects of the specific exercise programme were maintained after one year and significantly fewer patients in this group chose surgery. Surgery was significantly more often chosen by patients who had a low baseline shoulder score, and/or a full thickness rotator cuff tear.  All patients showed significant improvement in the clinical scores one year after inclusion or one year after surgery. These results support the concept that subacromial pain has a multifactorial aetiology and that the first line of treatment should be specific shoulder exercises. When conservative treatment fails, an acceptable result can be achieved with arthroscopic subacromial decompression. The rotator cuff status is important to consider when treating and studying these patients.

Mathematical musculoskeletal modeling and simulation provide a means for proactive injury prevention. To be effective, these models must physiologically replicate shoulder function. Although several muscle force prediction (MFP) shoulder models exist, few have attempted to integrate the force contributions of ligaments, especially the glenohumeral ligaments. The purpose of the current study was to integrate seven shoulder ligaments into an existing computational shoulder model, and analyze both individual ligament characteristics and the influence on the model outputs. Using data from the literature, seven shoulder ligaments were integrated into the model: the costoclavicular, conoid, trapezoid, coracohumeral, superior glenohumeral, middle glenohumeral, and inferior glenohumeral. 10 subjects performed isometric exertions in 56 posture-force combinations. Upper body posture and hand force collected were used as inputs for three different model versions; No-Ligaments (NL) included, Glenohumeral-Ligaments (GH) included, and All-Ligaments (AL) included. Electromyographic (EMG) signals from 11 muscle sites were used for comparison with model MFPs. The primary analysis focused on the differences between the GH and NL versions. Normalized EMG amplitudes were plotted against normalized MFPs from both models. Ligament effects on model outputs were measured by comparing changes in correlation between EMG and MFP, changes in slopes regression lines relating EMG to MFP, and the frequency of zero-force prediction by the model. Paired Student’s t-tests were used to measure significant differences. Results showed significant correlations (Pearson product) between EMG amplitude and MFP in the lower trapezius and infraspinatus muscles (p<0.01). No significant differences were found in r-values for these muscles between the NL and GH model. Slopes of regression lines decreased when GH ligaments were added, while the change in zero-force predictions varied by muscle. This study highlights the sensitivity of musculoskeletal models to the inclusion of ligament forces. Though correlations did not change, decreases in slope indicate increased force prediction by the GH model. Though zero-force predictions for some muscles increased, the results from those that decreased suggest muscles are active in postures where they were originally believed to be inactive. This finding suggests that inclusion of GH ligaments into our model may help predict antagonist muscle activity. However, further research is required.

Mathematical musculoskeletal modeling and simulation provide a means for proactive injury prevention. To be effective, these models must physiologically replicate shoulder function. Although several muscle force prediction (MFP) shoulder models exist, few have attempted to integrate the force contributions of ligaments, especially the glenohumeral ligaments. The purpose of the current study was to integrate seven shoulder ligaments into an existing computational shoulder model, and analyze both individual ligament characteristics and the influence on the model outputs. Using data from the literature, seven shoulder ligaments were integrated into the model: the costoclavicular, conoid, trapezoid, coracohumeral, superior glenohumeral, middle glenohumeral, and inferior glenohumeral. 10 subjects performed isometric exertions in 56 posture-force combinations. Upper body posture and hand force collected were used as inputs for three different model versions; No-Ligaments (NL) included, Glenohumeral-Ligaments (GH) included, and All-Ligaments (AL) included. Electromyographic (EMG) signals from 11 muscle sites were used for comparison with model MFPs. The primary analysis focused on the differences between the GH and NL versions. Normalized EMG amplitudes were plotted against normalized MFPs from both models. Ligament effects on model outputs were measured by comparing changes in correlation between EMG and MFP, changes in slopes regression lines relating EMG to MFP, and the frequency of zero-force prediction by the model. Paired Student’s t-tests were used to measure significant differences. Results showed significant correlations (Pearson product) between EMG amplitude and MFP in the lower trapezius and infraspinatus muscles (p<0.01). No significant differences were found in r-values for these muscles between the NL and GH model. Slopes of regression lines decreased when GH ligaments were added, while the change in zero-force predictions varied by muscle. This study highlights the sensitivity of musculoskeletal models to the inclusion of ligament forces. Though correlations did not change, decreases in slope indicate increased force prediction by the GH model. Though zero-force predictions for some muscles increased, the results from those that decreased suggest muscles are active in postures where they were originally believed to be inactive. This finding suggests that inclusion of GH ligaments into our model may help predict antagonist muscle activity. However, further research is required.

The present research quantified the shoulder rhythm for arm postures that represent the right-handed reachable workspace and compared 3 methods of scapular tracking: acromion marker cluster (AMC), stylus and scapular locator. The shoulder rhythm models can be incorporated into existing and future shoulder biomechanical models to determine shoulder geometry when simulating postures experienced in workplaces and thus have ergonomic implications for correctly identifying risk factors. The results of this research also provide guidance for future studies involving scapular tracking. Fourteen male and 14 female participants performed static arm postures spread over 5 elevation angles: 0, 45, 90, 135, 180 degrees, three elevation planes: 0, 45, 90 degrees to the frontal plane and, three axial rotations: maximum internal, neutral, and maximum external rotation. Kinematic data was recorded using a Vicon MX20+ motion-tracking system. Bone rotations were calculated using Euler angles and continuous prediction models were generated to estimate scapular and clavicular orientations based primarily on thoracohumeral relative orientations. Methods of scapular tracking were compared using repeated measures analysis of variance. Participant characteristics did not influence any of the scapular or the clavicular angles (p>.05). Axial rotation did not influence scapular retraction/protraction and elevation plane did not influence clavicular elevation (p>.05). Elevation angle was the largest contributor to lateral rotation and posterior tilt of the scapula and all clavicular angles. Plane of elevation was the largest contributor to scapular protraction. Using the stylus as the gold standard, the locator and the AMC underestimated lateral rotation, with a maximum difference of 11 degrees and 9 degrees between the locator and the stylus and AMC and the stylus measurements, respectively. The AMC and the locator overestimated posterior tilt at overhead postures and underestimated it at low elevation angles. The maximum difference between the AMC- and the locator- and the stylus-measured tilt was 10 degrees. The scapular locator consistently overestimated protraction by approximately 5 degrees. The AMC underestimated protraction in the frontal plane at low elevation angle but overestimated it at all other postures and the overestimation increased with plane of elevation, internal rotation and elevation angle. Overall, it is recommended to use AMC rather than the scapular locator to measure scapular position.