Incorporating Biomechanical Data in the Analysis of a University Student With Shoulder Pain and Scapula Dyskinesis


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Incorporating Biomechanical Data in the Analysis of a University Student With Shoulder Pain and Scapula Dyskinesis



Ricardo Matias, Mark A. Jones



Subjective Examination


Hugo is a Caucasian 23-year-old student undertaking a bachelor’s degree in electronic engineering. He has an active lifestyle and is of average weight for his height (80 kg and 1.80 m tall). Hugo is the youngest of three sons and currently lives at home while he studies. He presented without a medical referral with pain in his left shoulder. His pain arose suddenly 1 week ago without incident during a strength-training gym session while lifting a greater weight of 70 kg on a barbell bench press (usual weight 60–64 kg). He could not identify any other predisposing factor to the onset of his shoulder pain. He is right-hand dominant.


Initially, Hugo was not concerned because the pain was only momentary during the bench press and did not limit the rest of his workout or participation in daily activities. However, after a week of continued pain with these two gym exercises and the development of pain in overhead activities at home, Hugo came to physiotherapy.


As illustrated in the body chart (Fig. 27.1), Hugo reported pain in the anterolateral aspect of his left shoulder. Screening for other potential symptoms was negative, including numbness, pins and needles, vascular-associated symptoms and joint noises or sensations (e.g. feelings of instability). Hugo also reported no symptoms in other body areas (e.g. spine and other peripheral joints). At the initial physiotherapy appointment, he rated his shoulder pain as 0/10 at rest on a verbal numeric rating scale (VNRS) and 5/10 VNRS when his symptoms were at their worst.


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Fig. 27.1 Body chart illustrating area of Hugo’s symptoms. No symptoms were reported in any other body areas.

Hugo’s shoulder pain was provoked with arm movements into elevation. Movements below 90 degrees and hand behind back were not a problem. The pain was elicited immediately with elevation and went as soon as he lowered his arm. He had no problem sleeping, including lying on either side, and reported no morning stiffness or progression of pain through the day. There was no change in the area or pattern of his pain provocation since the initial onset except for the development of pain on elevation starting to affect his daily activities both at home and in laboratory tasks within his engineering classes.


Hugo is a keen gym participant who regularly dedicates 90 minutes, three times per week, of his time to strength training. He is devoted to his third-year bachelor studies and highly motivated to continue his laboratory activities and to studying to maintain his 75th percentile grades. Hugo reported having no previous musculoskeletal injuries or problems, including no previous shoulder or spinal pain.


His general health is excellent, with no known medical conditions. He had not had any imaging of his shoulder or attempted any management other than discontinuing the bench press in his workout. He has not required any pain medication, and the only medication he takes is Symbicort for asthma.


When asked about his understanding of his problem, he reported having ‘no idea’ but assumed he must have strained something when adding extra weight to his bench press. He was not overly concerned or distressed by his problem, although he was keen to resume his full workout and a bit worried about the shoulder pain compromising his engineering lab activities. Hugo’s goals were simply to get back to full activities without pain, and he was keen to follow any advice and exercise that was recommended, adding that, if possible, he would like to continue as much of his gym program as allowed while undergoing rehab.



Reasoning Question:



  1. 1. Please discuss your hypotheses regarding ‘pain type’ (nociceptive, neuropathic, nociplastic), possible ‘sources of symptoms’ and ‘pathology’, and potential ‘contributing factors’, including the basis for your reasoning.

Answer to Reasoning Question:


From the current subjective examination, there is no evidence of neurological symptoms or relevant history that would support a ‘neuropathic pain’ and no evidence of maladaptive cognitions, fears or behaviours that would support a nociplatic pain. Hugo’s pain was reported as being localized in the anterolateral aspect of his left shoulder, with a consistent, predictable pattern of symptom behaviour that supports a nociceptive-dominant pain type (Smart et al., 2012).


Potential sources of nociception considered most likely would include local somatic tissues such as subacromial tissues (bursa, rotator cuff, long head of biceps), glenohumeral capsule and ligaments, labrum and acromioclavicular joint (ACJ), as well as referral from cervical spine somatic structures and viscera, although neither of those is considered likely given his lack of cervical symptoms and good general health. There is no macro trauma to suggest a specific pathology. Instead, the mechanism of onset supports a tissue nociception associated with strain during his bench press (e.g. a subacromial or intra-articular tissue but less likely ACJ or capsule).


The most likely contributing factor is inadequate scapular and glenohumeral control and strength for the increased bench-press load attempted. Error in bench-press technique is also possible, although considered less likely given his gym experience. He could also have a pre-existing capsular laxity (e.g. congenital, generalized hypermobility), and that will be screened for in the physical examination.


Clinical Reasoning Commentary:


Although musculoskeletal clinicians’ diagnosis of ‘pain type’ can only be a hypothesis based on dominant features in the clinical presentation (see Chapters 1 and 2), it is nevertheless still an important hypothesis to consider up front because the greater the likelihood of a nociplastic pain type, the greater the caution required later in interpreting patient responses in the physical examination, where provocation of symptoms may be related to increased sensitization rather than local tissue strain or pathology. As discussed in Chapter 4, it is important to explicitly screen for potential psychosocial factors, initially through the patient interview, and if necessary also through questionnaire.


Similarly, although pathology cannot be validated through the shoulder clinical examination (interview or physical), the likelihood and nature of pathology, or in this case, tissue nociception, can be hypothesized based on the history and clinical presentation. Consideration of potential ‘contributing factors’ is particularly important with a spontaneous mechanism of onset such as this because both resolution of symptoms and prevention of recurrence require assessment and management of contributing factors.



Physical Examination


Physical examination procedures were intended to identify movement-related dysfunction and contributing factors that could support and direct clinical management decisions. Visual observation and physical clinical tests were used, along with three-dimensional kinematics and electromyographic analysis. Motion of the thorax, scapula and humerus was collected (with a sample rate of 120 Hz) using electromagnetic skin-mounted trakSTAR sensors (Ascension Technology, Burlington, Vermont) that were attached to the anterior face of sternal manubrium, to the flat surface on the superior acromion, and to the lateral side of the humerus, respectively. Motion data were reconstructed according to the International Society of Biomechanics recommendations for reporting upper extremity joint motion (Wu et al., 2005), providing a three-dimensional image that was then displayed for both Hugo and the therapist. All kinematic data were processed with The MotionMonitor software (Innovative Sports Training, Chicago, Illinois).


Muscle electromyographic activity was recorded (with a sample rate of 1000 Hz) using surface electrodes placed according to standard anatomic references (Ekstrom et al., 2003) over the bellies of the anterior deltoid, upper and lower trapezius, and serratus anterior muscles, in line with their fibre orientation. All electromyographic data were processed using a Physioplux system (PLUX Wireless Biosignals, Lisbon). Both Innovative Sports Training and PLUX software provided real-time biofeedback information using ‘The MotionMonitor Toolbox’ and the ‘Dynamic Shoulder Stability’ applications, respectively.



Posture and Alignment (No Symptoms at Rest)


In the standing position, observation demonstrated that Hugo did not present with any apparent shoulder girdle muscle asymmetry. At rest with the arms at 0 degrees of flexion, both his glenohumeral joints were anterior relative to an imaginary plumb line commencing from the base of support just anterior to the lateral malleolus of the ankle. When comparing both scapula orientations relative to the thorax by observation, the left scapula medial border and inferior angle were detached, representing an increased internal rotation or ‘winging’ dyskinesis.


When comparing the left scapula, three-dimensional orientation values at rest (45.3 degrees of internal rotation, 9.3 degrees of upward rotation and 11.9 degrees of anterior tilt) against data from impaired and non-impaired subjects (Lawrence et al., 2014), it can be concluded that Hugo had an increase of scapula internal rotation and upward rotation of 4.2 degrees and 3.9 degrees, respectively, and a minor difference in anterior tilt when compared with mean values of non-impaired subjects. Although the standard deviation of three-dimensional scapula orientation values from impaired and non-impaired subjects overlap, Hugo’s rest position was closer to the impaired subjects’ mean, supporting a clinical judgement of left scapula positional impairment at rest.




Impingement Tests



Note: Manual assistance to left scapula lateral rotation and posterior tilt during the Hawkins-Kennedy and Neer Impingement Tests decreased Hugo’s pain.



Shoulder Passive-Movement Testing


All active-movement tests repeated as passive-movement assessments were full range of movement with no pain provocation except for passive flexion and abduction, where range of movement was within normal limits but provoked his shoulder pain at the limit. Passive accessory movements at the glenohumeral, acromioclavicular and sternoclavicular joints were judged to have normal movement and end-feel, with no pain provocation. Passive glenohumeral stability tests (e.g. anterior, posterior, inferior and antero-inferior) and labral tests (e.g. ‘Active Compression Test [O’Brien et al., 1998], ‘Bicep Load II Test [Kim et al., 2001] and ‘Crank Test [Lui et al., 1996], plus variations) were negative, with no abnormal laxity detected and no provocation of pain, respectively.



Shoulder Palpation


No swelling, altered tissue texture or areas of tenderness were identified around the acromion, acromioclavicular joint, subcoracoid space or tissues overlying the humeral head.



Awareness and Dissociation of Thoracic Segmental Movement


While standing against the wall, Hugo was asked to focus on flexing and extending his thoracic spine, as if he had to curl every vertebra of his spinal column away (flexion) and roll back against the wall (extension). Although he was able to achieve this task after several trials, Hugo clearly demonstrated a lack of thoracic motion dissociation and awareness, as he constantly moved his thoracic spine as a block despite having good segmental mobility.


Still with Hugo standing against the wall, it was observed that the posterior borders of the acromion of both his left and right scapulae were notably spaced from the wall. If asked to modify his scapulae position in such a way that this space could be reduced, Hugo was able to correct the shoulder girdle posture without feeling any increase in tension in the pectoralis-minor area.



Active Cervical and Thoracic Movement Testing


All active cervical and thoracic movements were judged to have full range of movement with no provocation of symptoms.



Dynamic Rotary Stability Test (Magarey and Jones, 2003; Magarey and Jones, 2003a)


Gentle resistance was applied to isotonic internal and then external rotation performed at varying angles between 90 degrees and full elevation in the sagittal, frontal and scapular planes. Simultaneously, the therapist assessed at the anterior and posterior glenohumeral joint lines for any abnormal glenohumeral translation, as well as for pain provocation, weakness, reproduction of joint clicks and so forth. No abnormal translation was evident, and no pain or joint click was reproduced. External rotation strength was subjectively reduced (as judged by therapist and patient) when assessed toward full elevation compared to the same position of the left side. When repeated with scapular stabilization (i.e. ‘Scapular Retraction/Repositioning Test’ [Burkhart et al., 2000]), Hugo’s external rotation ‘weakness’ was significantly improved.



Muscle Activation Pattern (Assessed With Surface Electromyography [EMG])


During upper extremity movements, it is expected that the activation of the scapulothoracic muscles will occur in advance of the arm motion for preparing the scapula for the perturbation resulting from the implicit joint moments. This activation is referred to as ‘feedforward’ if it occurs prior or shortly after (<50 ms) the primer mobilizer (e.g. anterior fibres of the deltoid during flexion) because it cannot be initiated by feedback from the limb movement (Aruin and Latash, 1995). The temporal recruitment analysis of the lower trapezius and serratus anterior in relation to the onset of the anterior deltoid showed a feedforward pattern of both muscles in active shoulder flexion and abduction with the exception of a feedback pattern of the serratus anterior during arm abduction.




Questionnaire Assessment of Disability


To assess physical function and symptoms over time, two self-administered questionnaires were used:




Reasoning Question:



  1. 2. Please discuss your analysis of the physical findings with respect to your previous hypotheses regarding ‘pain type’, potential ‘source of symptoms’, ‘pathology’ and ‘contributing factors’. Also, on the basis of these findings, please highlight your plans for management.

Answer to Reasoning Question:


The physical examination findings were consistent with the previous hypothesis following the subjective examination that the pain type was nociceptive dominant. Pain was only provoked with a few tests, and it was repeatable and proportional to the behaviour of Hugo’s symptoms as he previously described. There was no widespread tenderness, as is commonly found with nociplastic pain, and no verbal or non-verbal behaviour during either the subjective or physical examination suggestive of hypervigilance or catastrophizing.


No specific pathology was incriminated by the physical examination findings. Pain was only provoked at the end range of active and passive elevation, with normal range of movement and no pain provocation on palpation, resisted isometric tests or labral tests. Although it is not possible to clinically confirm the source of nociception, collectively, the examination supports a subacromial source of nociception, such as a minor bursitis or reactive tendinopathy.


Scapular muscle impairments (dyskinesis, timing of activation and strength) are the most significant findings in Hugo’s physical examination. Although these can be a consequence of shoulder pain via ‘pain inhibition’, they also are potential contributing factors that may have predisposed to his ‘strain’ during his bench-press onset of pain. Regardless, they now are demonstrated in Hugo’s physical examination to be contributing to his current pain and weakness (i.e. improved with scapular assistance) and therefore will become the focus of management.


Reasoning Question:



  1. 3. Use of three-dimensional kinematic analysis would not be common in most musculoskeletal clinics. Would you discuss the validity of the system you use and the clinical value you believe it offers?

Answer to Reasoning Question:


The study of the shoulder complex has been a great challenge for all those who have been interested in it. The challenge is even greater when a clinician uses simple visual observation to perceive and analyze scapula movements. Electromagnetic systems have been extensively used to measure three-dimensional scapular kinematics during shoulder movements in impaired and non-impaired individuals (e.g. Haik et al., 2014; Ludewig and Cook, 2000). To track the thorax, scapula and humerus motion, sensors are normally attached with double-sided tape to the anterior face of sternal manubrium, to the flat surface on the superior acromion and to the lateral aspect of the humerus. This skin-mounted sensor method has proven to be valid for the measurement of scapula kinematics (Karduna et al., 2001) and reliable for both within- and in-between-day assessments (Haik et al., 2014). During Hugo’s treatment, an electromagnetic system was used to accurately and reliably reconstruct scapula kinematics, generating information important to both our physical examination and to our management decisions by providing a source of real-time kinematic biofeedback.


The study of individual muscles’ roles in controlling and stabilizing the scapula has been primarily based on muscle anatomy and activity measured via EMG. Musculoskeletal models provide the opportunity to infer muscle function from the internal mechanics of the scapula in response to muscle forces. A new model capable of reproducing scapulothoracic joint physiological movements in response to applied forces to accurately track scapula kinematics has been recently published and is freely available for download (Seth et al., 2016). This model shows great promise for revealing the interactions of complex skeletal and muscle dynamics that are involved in producing healthy and dysfunctional shoulder movements.


Although electromagnetic systems (along with other systems such as the optoelectronic systems and inertial measurement units) are undoubtedly of great value for accurate human motion reconstruction, computational modeling and simulation of the musculoskeletal system will bring new insights regarding movement dynamics. With the observed price reduction of the motion-capture systems, the increased efficiency of modern computers and freely available modeling and simulation software platforms such as the OpenSim Project (Delp et al., 2007), an unprecedented opportunity arises to reduce the gap between human motion analysis and its use in clinical practice. A complementary approach that merges clinical and biomechanical information will help therapists better understand and manage patients with movement-related impairments like the scapula dyskinesis present in Hugo’s shoulder-elevation movements.


Clinical Reasoning Commentary:


The answer to Reasoning Question 2 illustrates how hypotheses formulated through the subjective examination are not fixed; rather, they are ‘tested’ against findings from the physical examination to build an evolving understanding of the patient and their problem. Because physical impairment in posture symmetry and scapular dyskinesis can exist without symptoms or pathology, the relevance of Hugo’s dyskinesis impairments is specifically tested. Having established their likely relevance in contributing to his current pain and weakness, they then become a focus of treatment, where later re-assessments will further test both the effectiveness of the treatment and the hypothesis that these scapular muscle impairments are relevant to Hugo’s symptoms and activity restrictions.


The inclusion of the three-dimensional kinematic analysis is an impressive and exciting means of objectively establishing and measuring scapular dyskinesis impairment. Musculoskeletal examination relies considerably on clinicians’ skills of observation and feel. Although procedural skill, including communicative proficiency, is a recognized attribute of expert clinicians, the subjective nature of many musculoskeletal examination judgements will always be a limiting factor to their validity and a challenge to less experienced clinicians. As highlighted in Chapter 1, clinical reasoning is only as good as the information on which it is based. As such, any means to improve the clinical objectivity and validity of our assessments should reduce our perceptual errors and, in turn, better inform our clinical reasoning.



Management


A scapula-focused intervention was used based on the sequential cognitive, associative and autonomous stages of motor relearning (Shumway-Cook and Woolacott, 2001) as a framework while promoting the integration of local and global muscle function (Comerford and Mottram, 2001) tailored to Hugo’s clinical presentation. Three-dimensional kinematics and an EMG system were used both for outcomes assessment and as a real-time source of biofeedback. The MotionMonitor software allowed quick clinical setup of Hugo with three electromagnetic sensors that accurately reconstructed his left scapula motion with respect to the thorax, in Euclidean three-dimensional space, according to the Euler angle sequence: retraction/protraction, lateral/medial rotation and anterior/posterior scapula tilt. The Physioplux system was simultaneously used to record muscles’ onset and activity (normalized with respect to maximum voluntary isometric contraction) during the therapeutic exercises. Both software packages permitted modeling the graphical representation of both motion variables and, specifically, which parameters would be displayed in real time.



First-Appointment Treatment


The main goal of Hugo’s management program was to restore his functioning levels, abolish pain and restore scapula neuromuscular control and strength. Based on the most recent research findings on the association of scapula dyskinesis and glenohumeral joint pathologies (e.g. Kibler et al., 2013; Ludewig and Reynolds, 2009), management commenced with an explanation of the main physical findings and recommendation for therapy. This education commenced with an explanation of Hugo’s movement-related impairments and the likely associated biomechanical mechanisms and daily activities that could be contributing to his movement impairments. Understanding was facilitated with the use of a skeleton and a dynamic video of normal scapulohumeral movement (‘shoulder decide’). During this process, Hugo was encouraged to share and discuss his own ideas and thoughts regarding his shoulder problem. After this, the most appropriate management for his presentation was outlined based on emerging evidence and personal experience, with emphasis on the use of therapeutic exercise to reduce imbalances in neuromuscular activity and motor control (e.g. Başkurt et al., 2011; Struyf et al., 2013). As I explained how we could merge therapeutic motor-relearning exercises with real-time EMG and three-dimensional kinematic biofeedback, it was clear that these motion technologies sparked Hugo’s curiosity and motivation. Hugo was enthusiastic about the proposed management plan.


Pain and function were set as primary outcomes: the VNRS cutoff point defined to distinguish the presence or absence of dysfunction was zero. A reported minimal clinically important difference of 10.2 points and ranging from 8 to 13 points for the DASH and SPADI questionnaires, respectively, was used to determine the clinical significance of the results (Roy et al., 2009). Their cutoff points were set to 2.67/100 for DASH and 3.66/100 for SPADI (MacDermid et al., 2007). Scapula alignment and kinematic control were defined as normal when scapulothoracic angles at rest fell within 41.1 degrees (±6.24) of internal rotation, 5.4 degrees (±3.12) of upward rotation and 13.5 degrees (±5.54) of anterior tilt and with published mean values of non-impaired subjects at 30 degrees and 90 degrees of humerothoracic flexion and abduction, respectively (Lawrence et al., 2014). ‘Good’ scapula neuromuscular control was defined as Hugo being able to integrate scapula stabilizer activity (feedforward pattern measured with EMG) while correctly performing scapula-focused exercises throughout the three stages of motor relearning. For each stage, three-dimensional scapula kinematic values and tolerance errors were defined and monitored with an electromagnetic three-dimensional kinematic system. In order to achieve these outcomes, a weekly 1-hour session was used, and home-based exercises were prescribed. Outcome results are summarized in Table 27.1.


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Apr 2, 2020 | Posted by in SPORT MEDICINE | Comments Off on Incorporating Biomechanical Data in the Analysis of a University Student With Shoulder Pain and Scapula Dyskinesis

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