Scapular Motion Research Articles

Ab. No. 153 Comparison of 3d Scapular Kinematics of the Affected and Unaffected Shoulder in Subjects With Unilateral Adhesive Capsulitis

Introduction: The purpose of the study is to compare 3D scapular kinematics and scapulohumeral rhythm of affected and unaffected side in subjects with unilateral adhesive capsulitis at various degrees of elevation and lowering during flexion. Improving precise measurement of all scapular rotations will enhance comprehension of shoulder dysfunction and may aid in the development of targeted rehabilitation strategies. Methods: 20 subjects with unilateral adhesive capsulitis, average age (51.7±7.6 years) with symptoms since 4.3±2.5 months using purposive sampling were included. 3-dimensional Euler angles using the International Society of Biomechanics standards were estimated during flexion via Ascension trakSTAR sensors integrated with Motion Monitor Software. The scapular movements (upward/downward rotation, internal/external rotation and anterior/posterior tilt) were measured at rest(0°), 30°, 60°, 90° and 120° of arm elevation and the scapulohumeral rhythm was calculated between these motion increments. The kinematic variables at rest were compared using paired t-tests and scapular kinematic variables were compared across angles of elevation and sides for each phase separately using 2-way repeated measures ANOVA. In case of significant interactions, post hoc testing was done using Tukey Kramer test for pairwise comparisons. Results: The affected side was 6.81° more upwardly rotated than unaffected at 90°. There was statistical difference between phases of elevation and lowering for upward rotation at 60° and 90°, anterior tilt at 30°, 60° and 90° and scapular internal rotation at 90° and 120°. The differences at 120 degrees could not be measured in all subjects. The scapulohumeral rhythm was different between sides only for 60°-90° during flexion. Conclusion: There was a more substantial scapular substitution beyond the middle region of arm elevation during shoulder flexion. Beyond correcting the scapular shrug that would have increased scapular tilt, therapists may focus on reducing scapular upward rotation.

The Effect of Scapular Orientation on Measures of Rotator Cuff Tendon Impingement: A Simulation Study

Mechanical impingement of the rotator cuff tendons against the acromion (subacromial) and glenoid (internal) during shoulder motions has long been thought to contribute to tears. Clinically, the risk for impingement is thought to be influenced by scapular movement impairments. Therefore, our purpose was to determine the extent to which simulated changes in scapular orientation impact the proximity between the rotator cuff tendon footprint and the acromion and glenoid during scapular plane abduction. Specifically, shoulder kinematics were tracked in 25 participants using a high-speed biplane videoradiography system. Scapular movement impairments were simulated by rotating each participant’s scapula from their in vivo orientation about the scapular axes (±2°, ±5°, and ±10°). Subacromial and internal proximities were described using minimum distances, proximity center locations, and prevalence of contact. Statistical parametric mapping was used to investigate the extent to which these measures were impacted by simulated changes in scapular orientation. Simulated changes in scapular orientation significantly altered proximity patterns in a complex manner that depended on the impingement mechanism, humerothoracic elevation angle, and magnitude of the simulated change. Clinicians should be mindful of these factors when interpreting the potential effects during a clinical examination.

Humeral head size predicts baseplate lateralization in reverse shoulder arthroplasty: a comparative computer model study

BackgroundIn reverse shoulder arthroplasty (RSA), the ideal combination of baseplate lateralization (BL), glenosphere size (GS) and overhang (GOH) with a commonly used 145° neck shaft angle (NSA) is unclear. This is the first study evaluating correlations of body height (BH), humeral head size (HS), glenoid height (GH) and association of gender with best glenoid configurations for range of motion (ROM) maintaining anatomic lateralization (aLAT) for optimized muscle length in 145° and less distalized 135° RSA. MethodsIn this computer model study, 22 CTs without joint narrowing were analyzed (11 male/female). A standardized semi-inlay 145° platform stem was combined with 20 glenoid configurations (baseplate (B) 25, 25+3/+6 lateralized (l), 29, 29+3/6l combined with glenosphere36, 36+2eccentric (e), 36+3l, 39, 39+3e, 39+3l , 42, 42+4e). Abduction-adduction, flexion-extension, external rotation-internal rotation, total ROM (TROM) and total notching relevant (TNR) ROM were computed, best TROM models respecting aLAT (-1mm to +1mm) and HS/GH recorded. Secondly, the 145° models (Ascend Flex stem; Stryker, Kalamazoo, MI, USA) were converted and compared to a 135° inlay RSA (New Perform stem; Stryker, Kalamazoo, MI, USA) maintaining GOH (6.5-7mm) and aLAT. ResultsBest 145° models had eccentric glenospheres (mean BL: 3.5mm, GOH 8.8mm, GS 38.1mm, distalization (DIS) 23mm). The 135° models had concentric glenospheres, mean BL 3.8mm, GOH 6.9mm, GS 39.7mm, DIS 14.1mm. Head size showed the strongest positive correlation with BL in 145° and 135° models (0.65/0.79). Despite reduced GOH in smaller females with a 135° NSA, adduction, external rotation, extension, TNR ROM and TROM were significantly increased (p=0.02, p=0.005, p=0.005, p=0.004, p=0.003), abduction however reduced (p=0.02). The same trends were seen for males. ConclusionsHead size is a practical measure in surgery or preoperatively, and the strong positive correlation with BL is a useful planning aid. Despite reduction of GOH, conversion to a less distalized 135° NSA is powerful to maintain and even significantly increase all components of TNR ROM (extension/external rotation/adduction) in small females with the drawback of reduced abduction which may however be compensated by scapula motion. Lateralization with a less distalized 135° RSA optimizes muscle length, may facilitate subscapularis repair and maintains highest rigid body motion.

Effects of a dry-land strengthening exercise program with elastic bands following the Kabat D2 diagonal flexion pattern for the prevention of shoulder injuries in swimmers.

Background: During the repetitive execution of the swimming strokes, the muscles responsible for the internal rotations of the shoulders tend to become stronger compared to the muscles that oppose these movements. The aim of this study was to analyse the effect of a strengthening program for the shoulder rotator muscles using elastic band exercises in a diagonal Kabat pattern (D2 for flexion) in swimmers, to develop an effective, quick and easy-to-implement protocol for preventive training routines. Methods: A randomized controlled trial design was carried out. Internal and external rotation range of movement, isometric strength of the muscles responsible for internal and external rotation of the shoulder, scapular movements, was measured at the beginning of the study and after 8weeks post-intervention. A total of 22 male swimmers participated in the study and were randomly assigned to either an experimental group (n = 11) or a control group (n = 11). The experimental group underwent a 8-week shoulder-strength program using elastic bands, while the control group focused on aquatic training. Results: The strength-training program resulted in an improvement in the isometric strength of the muscles responsible for external rotation and a better balance between the shoulder rotator muscles in the experimental group. However, these improvements have not been significant (p > 0.05). Conclusion: The strengthening exercise program showed minimal improvement in shoulder rotation strength and range of motion. These findings suggest that the prescribed shoulder-strengthening exercise could be a quick-beneficial dry-land training option to improve external rotation shoulder strength or range of motion, but more studies with larger sample sizes and more weeks of treatment are needed to determine the efficacy of this protocol.

Reliability and Concurrent Validity of Smartphone Clinometer Application for Measuring Scapular Rotations in Subjects With and Without Shoulder Pain.

Clinical assessment of scapular motion is obscured by a lack of clinically accessible and feasible angular measurement tools. This study evaluates the reliability and validity of the smartphone "Clinometer" app in measuring scapular upward rotation (UR) and anteroposterior tilt. Psychometric analysis. We recruited 57 participants-10 with and 47 without shoulder pain. Two physical therapists consecutively measured both scapular movements using the Clinometer app at the arm by the side (rest), 30°, 60°, 90°, and 120° of humeral elevation in the scapular plane; one therapist measured again after 2days. For evaluating concurrent validity, we compared the Clinometer scores with those measured using an electromagnetic motion capture system in 10 healthy participants. Intraclass correlation coefficients (ICC) with standard error of measurement (SEM) and minimal detectable difference at 90% confidence intervals (MDD90) were calculated. Concurrent validity was evaluated using repeated-measures analysis of variance followed by post hoc testing with Tukey-Kramer test (P < .05). We observed good intrarater reliability (ICC: UR = .76-.85, tilt = .69-.9; SEM: 2.2°-3.5°; MDD90: ∼5°-8°) and moderate to good interrater reliability (ICC: UR = .66-.78, tilt = .66-.76; SEM: 3.6°-8°; MDD90: ∼9°-18°) for both rotations. The Clinometer scores for UR were comparable to electromagnetic motion capture system at all angles except 90° (difference ∼8°); for scapular tilt, the scores were comparable only at rest and 30° elevation. The Clinometer app is reliable and valid for measuring scapular UR throughout and for scapular tilt at lower humeral elevation angles. The MDD90 values for scapular rotations computed in this study can be helpful in rehabilitation planning and future research.

Does calibration pose improve scapular kinematic repeatability in functional tasks?

Tracking scapular motion can be challenging. More research is needed to determine the best practices for scapular measurement in multi-planar tasks. The purpose of this study was to compare the repeatability of scapular kinematics during a functional task protocol calculated from different calibration procedures. It was hypothesized that select poses would improve repeatability in specific tasks. The torso, humerus, and scapula were tracked with optical motion capture in two sessions for ten pain-free participants. Scapular calibrations were completed in five poses: neutral, maximum elevation, 90° abduction, hand to contralateral shoulder, and hand to back. Each participant completed eight functional tasks (Comb Hair, Wash Axilla, Tie Apron, Overhead Reach, Side Reach, Forward Transfer, Floor Lift, Overhead Lift). Scapular angles were calculated with five different calibration procedures and extracted at 30° increments of humeral elevation in each task. Mean difference, limits of agreement, intraclass correlations, and minimal detectable change (MDC) were calculated for each task and elevation level. The inclusion of different calibration poses did not markedly improve outcomes over the maximum elevation double calibration for most tasks. Using this calibration procedure, median MDCs were 10.0° for upward rotation, 13.7° for internal rotation, and 9.8° for tilt.

Scapular dyskinesis after treatment of proximal humerus fracture, a 3-dimensional motion analysis and clinical outcomes.

The alteration of scapular kinematics can predispose patients to shoulder pathologies and dysfunction. Previous literature has associated various types of shoulder injuries with scapular dyskinesis, but there are limited studies regarding the effect that proximal humeral fractures (PHFs) have on scapular dyskinesis. This study aims to determine the change in scapulohumeral rhythm following treatment of a proximal humerus fracture as well as differences in shoulder motion and functional outcomes among patients who presented with or without scapular dyskinesis. We hypothesized that differences in scapular kinematics would be present following treatment of a proximal humerus fracture, and patients who presented with scapular dyskinesis would subsequently have inferior functional outcome scores. Patients treated for a proximal humerus fracture from May 2018 to March 2021 were recruited for this study. The scapulohumeral rhythm and global shoulder motion were determined using a 3-dimensional motion analysis (3DMA) and the scapular dyskinesis test. Functional outcomes were then compared among patients with or without scapular dyskinesis, including the SICK (scapular malposition, inferomedial border prominence, coracoid pain and malposition, and dyskinesis of scapular movement) Scapula Rating Scale, the American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form (ASES), the visual analog scale (VAS) for pain, and the EuroQol-5 Dimension 5-Level questionnaire (EQ-5D-5L). Twenty patients were included in this study with a mean age of 62.9±11.8 years and follow-up time of 1.8±0.2 years. Surgical fixation was performed in 9 of the patients (45%). Scapular dyskinesis was present in 50% of patients (n=10). There was a significant increase in scapular protraction on the affected side of patients with scapular dyskinesis during abduction of the shoulder (P=.037). Additionally, patients with scapular dyskinesis demonstrated worse SICK scapula scores (2.4±0.5 vs. 1.0±0.4, P=.024) compared to those without scapular dyskinesis. The other functional outcome scores (ASES, VAS pain scores, and EQ-5D-5L) showed no significant differences among the 2 groups (P=.848, .713, and .268, respectively). Scapular dyskinesis affects a significant number of patients following treatment of their PHFs. Patients presenting with scapular dyskinesis exhibit inferior SICK scapula scores and have more scapular protraction during shoulder abduction compared to patients without scapular dyskinesis.

A Diagonal Movement Pattern of Arm Elevation and Depression in Overhead Throwing Athletes: An Exploratory Kinematic Analysis for Clinical Application

Assessing scapular position and motion during functional arm movement patterns may add relevant information to the evaluation of the clinical status and athletic performance of overhead sports athletes’ shoulders. This study aimed to examine the three-dimensional scapular kinematics of elite volleyball players with (n = 11) and without scapular dyskinesis (n = 11) in comparison to non-athletes (n = 27). Four distinct arm elevation/depression tasks were assessed: shoulder abduction/adduction, flexion/extension, scaption, and a diagonal movement pattern mimicking throwing (proprioceptive neuromuscular facilitation diagonal 2 for flexion/extension or PNF–D2–flx/ext). Kinematic data was recorded from the spiking/dominant shoulder using an electromagnetic system (FASTRAK, Polhemus Inc., Colchester, VT, USA); MotionMonitor v9 software, Innovative Sports Training, Inc., Chicago, IL, USA). The study compared scapular rotations at 15° intervals of humero-thoracic (HT) angles, ranging from minimum to 120°. Significantly different 3D scapular kinematics were observed between traditional arm motion tasks and PNF–D2 arm motion task (HT angle × task interaction effect, p &lt; 0.001, 0.275 ≤ ηp2 ≤ 0.772). However, when considering the combined influence of phase, HT angle, task, and group factors, no differences were found between groups (phase × HT angle × task × group, p ≥ 0.161, 0.032 ≤ ηp2 ≤ 0.058). The inclusion of a functional arm movement pattern when evaluating scapular position and movement in overhead athletes does not appear to be mandatory. However, these findings are preliminary and highlight the need for more research in this area.

Influence of scapular motion cues on trapezius muscle activity during Y exercise.

The Y exercise is a therapeutic exercise facilitating lower trapezius muscle activity. To identify the effects of scapular movement cues (posterior tilt vs. posterior tilt with adduction/depression) on trapezius muscle activity during Y exercise. Fifteen healthy men without current shoulder pain performed general Y exercise; Y exercise with cues for scapular posterior tilt; and Y exercise with cues for scapular posterior tilt, adduction, and depression. Electromyography (EMG) data for the trapezius muscles were collected during Y exercise. The posterior tilt angle of the scapula was measured in the prone position with and without cues for scapular posterior tilt using an inclinometer application. The greatest lower trapezius muscle activity was observed during Y exercise with cues for scapular posterior tilt, while the greatest EMG activity of the upper trapezius was observed during Y exercise with cues for scapular posterior tilt, adduction, and depression (p< 0.05). Middle trapezius muscle activity did not significantly differ among the three Y exercise conditions (p= 0.175). Cues for scapular posterior tilt significantly increased the scapular posterior tilt angle in the prone shoulder abduction position (p= 0.007). Cues for scapular posterior tilt were most effective in facilitating lower trapezius muscle activity during Y exercise.

Scapula dyskinesis in medium size full-thickness supraspinatus muscle tears

Scapular motion abnormality in rotator cuff tears is a well-known symptom, but its significance is not clear. Some authors consider it as a cause of rotator cuff tear, others as a consequence of the disease. The aim of our study was to assess the changes in scapular motion in medium size full-thickness rotator cuff tear of degenerative origin compared to a healthy control group. 10 healthy (control group) and 9 subjects with a medium size (1-3 cm), complaining rotator cuff tear (study group) were included in our study, in whom we analyzed the movements of the shoulder girdle, including the scapula, during sagittal and scapular plane flexion using a VICON 3D motion capture system and U.L.E.M.A. motion analysis software. A two-sample t-test was used to test whether significant differences in scapular posterior tilting, upward rotation and protraction values were observed between the two groups for each humeral flexion angular position. In the study group, a significant increase in scapular protraction was demonstrated in sagittal arm elevations at 40 and 50 degrees of arm elevation compared to the control group (p<0.05), whereas no significant difference in scapular upward rotation and posterior tilting was demonstrated. During scapular plane flexion, no significant difference in scapular movements was demonstrated compared to the control group. Scapular dyskinesis is already present in cases of medium size rotator cuff tears. In scapular dyskinesis, a significant difference in protraction is first observed, which may affect scapular upward rotation and tilting as the tear continues to grow. Orv Hetil. 2023; 164(31): 1213-1221.

Changes in blood flow in the dorsal scapular artery and relationship to shoulder joint function in rotator cuff tears

One of the pain-related factors in rotator cuff tears (RCTs) is abnormal scapular motion, which is thought to be related to the levator scapulae muscle activation. Additionally, attention has recently focused on the peak systolic velocity (PSV) as one of the causes of pain, but blood flow outside of the vessels supplying the rotator cuff has not been clarified. This study aimed to determine the difference in PSV in the dorsal scapular artery (DSA), which is the vessel that supplies the levator scapulae muscles, and the association between PSV and pain and shoulder function in patients with RCTs between the tear and nontear sides. This study included 31 patients with RCTs with tear and nontear sides. Magnetic resonance imaging and radiographic examinations included Cofield classification, Goutallier classification, thickening of the coracohumeral ligament, and measurement of the acromiohumeral interval. Clinical evaluation included an automatic range of motion (ROM) for flexion, abduction, and external rotation (ER), a visual analog scale, and the Shoulder36. PSV was evaluated using ultrasound pulsed Doppler mode to assess PSV of DSA. The PSV of DSA on the first rib was drawn in the medial aspect of the suprascapular angle in the long axis, and the maximum PSV waveform was measured three times. The average value was used for further analysis. The PSV in the DSA was significantly higher (P=.04, 95% confidence interval: 0.2-7.6) on the tear (22.6±7.4 cm/s) than the nontear sides (18.9±6.9 cm/s). In addition, a significant negative correlation (r=-0.46, P=.0087) was found between PSV in DSA and ER on the tear side. This study revealed a significantly increased PSV in the DSA on the tear side in RCTs and negatively correlated with ER ROM. The results suggest that increased PSV in the DSA may contribute to ER ROM limitation in the glenohumeral joint.

Characterizing moment arms of the coracobrachialis and short head of biceps in native shoulders and after reverse total shoulder arthroplasty during elevation and rotation: a modeling study.

Reverse total shoulder arthroplasty (RTSA) alters the line of action of muscles around the glenohumeral joint. The effects of these changes have been well characterized for the deltoid, but there is limited information regarding the biomechanical changes to the coracobrachialis (CBR) and short head of biceps (SHB). In this biomechanical study, we investigated the changes to the moment arms of the CBR and SHB due to RTSA using a computational model of the shoulder. The Newcastle Shoulder Model, a pre-validated upper-extremity musculoskeletal model, was used for this study. The Newcastle Shoulder Model was modified with bone geometries obtained from 3-dimensional reconstructions of 15 nondiseased shoulders, constituting the native shoulder group. The Delta XTEND prosthesis, with a glenosphere diameter of 38 mm and polyethylene thickness of 6 mm, was virtually implanted in all the models, creating the RTSA group. Moment arms were measured using the tendon excursion method, and muscle length was calculated as the distance between the muscle's origin and insertion points. These values were measured during 0°-150° of abduction, forward flexion, scapular-plane elevation, and -90° to 60° of external rotation-internal rotation with the arm at 20° and 90° of abduction. Statistical comparisons between the native and RTSA groups were analyzed using 1-dimensional statistical parametric mapping (spm1D). Forward flexion moment arms showed the greatest increase between the RTSA group (CBR, 25.3±4.7 mm; SHB, 24.7±4.5 mm) and native group (CBR, 9.6±5.2 mm; SHB, 10.2±5.2 mm). The CBR and SHB were longer in the RTSA group by maximum values of 15% and 7%, respectively. Both muscles had larger abduction moment arms in the RTSA group (CBR, 20.9±4.3 mm; SHB, 21.9±4.3 mm) compared with the native group (CBR, 19.6±6.6 mm; SHB, 20.0±5.7 mm). Abduction moment arms occurred at lower abduction angles in the RTSA group (CBR, 50°; SHB, 45°) than in the native group (CBR, 90°; SHB, 85°). In the RTSA group, both muscles had elevation moment arms until 25° of scapular-plane elevation motion, whereas in the native group, the muscles only had depression moment arms. Both muscles had small rotational moment arms that were significantly different between RTSA and native shoulders during different ranges of motion. Significant increases in elevation moment arms for the CBR and SHB were observed in RTSA shoulders; these increases were most pronounced during abduction and forward elevation motions. RTSA also increased the lengths of these muscles.

Non-operative management of shoulder osteoarthritis: Current concepts

Glenohumeral osteoarthritis (OA) is one of the most common causes of shoulder pain. Conservative treatment options include physical therapy, pharmacological therapy, and biological therapy. Patients with glenohumeral OA present shoulder pain and decreased shoulder range of motion (ROM). Abnormal scapular motion is also seen in patients as adaptation to the restricted glenohumeral motion. Physical therapy is performed to (1) decrease pain, (2) increase shoulder ROM, and (3) protect the glenohumeral joint. To decrease pain, it should be assessed whether the pain appears at rest or during shoulder motion. Physical therapy may be effective for motion pain rather than rest pain. To increase shoulder ROM, the soft tissues responsible for the ROM loss need to be identified and targeted for intervention. To protect the glenohumeral joint, rotator cuff strengthening exercises are recommended. Administration of pharmacological agents is the major part next to physical therapy in the conservative treatment. The main aim of pharmacological treatment is the reduction of pain and diminution of inflammation in the joint. To achieve this aim, non-steroidal anti-inflammatory drugs are recommended as first-line therapy. Additionally, the supplementation of oral vitamin C and vitamin D can help to slow down cartilage degeneration. Depending on the individual comorbidities and contraindications, sufficient medication with good pain reduction is thus possible for each patient. This interrupts the chronic inflammatory state in the joint and, in turn, enables pain-free physical therapy. Biologics such as platelet-rich plasma, bone marrow aspirate concentrate, and mesenchymal stem cells have gathered increased attention. Good clinical outcomes have been reported, but we need to be aware that these options are helpful in decreasing shoulder pain but neither stopping the progression nor improving OA. Further evidence of biologics needs to be obtained to determine their effectiveness. In athletes, a combined approach of activity modification and physical therapy can be effective. Oral medications can provide patients with transient pain relief. Intra-articular corticosteroid injection, which provides longer-term effects, must be used cautiously in athletes. There is mixed evidence for the efficacy of hyaluronic acid injections. There is still limited evidence regarding the use of biologics.

Scapular kinematics and muscle activity during Yi Jin Bang exercises.

Introduction: Scapular dyskinesis is commonly associated with subacromial pain syndrome (SAPS). Addressing scapular dyskinesis is widely accepted as an important component of shoulder rehabilitation. Our previous randomized controlled trial showed that Yi Jin Bang (YJB) exercises could effectively manage SAPS, but scapular motions and muscle activity during YJB exercises remain unknown. This study examined scapular kinematics synchronously with scapular muscle activation during YJB exercises. Methods: Thirty healthy participants with no shoulder complaints were enrolled in this study. Three-dimensional (3D) scapular kinematics and electromyography (EMG) activation of the upper trapezius, middle trapezius, lower trapezius, serratus anterior, anterior deltoid, middle deltoid, and posterior deltoid were synchronously measured during nine YJB movements. Results: During all YJB movements, the scapula was upwardly rotated and anteriorly tilted, with more upward rotation and a similar or less anterior tilt than the mean resting scapular angle. Column rotation, arm crossover, shoulder support circle, and armpit support high lift generated more internal rotation than the mean resting scapular angle, with the angles of internal rotation significantly greater than the other five movements (p < 0.001). Regarding EMG activity, all YJB movements elicited low activity (1.42%-19.19% maximal voluntary isometric contraction [MVIC]) from the upper trapezius and posterior deltoid and low to moderate activity (0.52%-29.50% MVIC) from the middle trapezius, lower trapezius, serratus anterior, anterior deltoid, and middle deltoid. Conclusion: YJB exercises could be useful in the middle to later phases of shoulder rehabilitation. For patients with insufficient external rotation, some YJB movements should be prescribed with caution.

Variation in Scapulohumeral Rhythm on Dynamic Radiography in Pathologic Shoulders: A Novel Diagnostic Tool.

Alterations in scapulohumeral joint kinematics occur in various shoulder pathologies. Conventional imaging provides a static assessment of soft tissue and morphologic changes. Quantifying the scapulohumeral rhythm (SHR), using Dynamic Digital Radiography (DDR) can offer clinicians a greater understanding of the pattern and extent of motion impairment as well as reliably monitor changes throughout the treatment course. The purpose of this study was to analyze the SHR of patients diagnosed with small (SRCT) and massive rotator cuff tears (MRCT), adhesive capsulitis (AC), and glenohumeral osteoarthritis (GH-OA) and compare their measurements to those of patient controls with healthy shoulders using DDR. The sequences of pulsed radiographs collated in DDR to create a moving image were prospectively analyzed during humeral abduction in normal controls and in 4 distinct shoulder pathology groups: SRCT, MRCT, AC, and GH-OA. GH and ST joint angles were measured at 0-30°, 30-60°, 60-90°, and maximal coronal plane humeral abduction. SHR was defined as the ratio of the change in humeral abduction over the change in scapula upward rotation during humeral abduction and was calculated within the above angle intervals. 121 shoulders were analyzed. 40 normal controls were compared to 13 SRCT, 29 MRCT, 16 AC, and 23 GH-OA. SHR during humeral abduction differed significantly in patients with MRCT (1.91 ± 0.72), AC (1.55 ± 0.37) and GH-OA (2.31 ± 1.01) compared to controls (3.39 ± 0.79). When analyzed across 30o intervals of abduction, there was a significantly lower SHR found at 0-30°, 30-60° and 60-90° in MRCT, AC, and GH-OA across each motion range compared to controls. Control patients had an arc of abduction of 103° ± 32° which was significantly larger than all other pathologies (MRCT: 76° ± 23°, SRCT: 81° ± 21°, AC: 65° ± 27°, GH-OA: 71° ± 35°) and an average scapular abduction of 33° ± 14°, which was significantly less than patients with a MRCT (46° ± 10°) and AC (65° ± 27°). SHR remained significantly lower throughout shoulder abduction in MRCT (43.65%), AC (-54.29%), and GH-OA (32.01%) compared to controls. When isolating for humeral and scapular motion, all 4 pathologies had decreased GH abduction, while AC and MRCT had an increased scapular compensatory motion compared to controls. Quantifying kinematic patterns like SHR using DDR can be implemented as a novel, safe, and cost-effective method to diagnose shoulder pathology and to monitor response to treatment.

The effect of EMG biofeedback training on muscle activation in an impingement population

Subacromial impingement syndrome (SAIS) is one of the most diagnosed causes of pain in the upper extremity. The purpose of this study was to investigate muscle activity between asymptomatic and SAIS shoulders on the same subject while understanding the effectiveness of EMG biofeedback training (EBFB) on bilateral overhead movements. Ten participants (7 male), that tested positive for 2/3 SAIS clinical tests, volunteered for the study. Bilateral muscle activity was measured via electrodes on the upper trapezius (UT), lower trapezius (LT), serratus anterior (SA), and lumbar paraspinals (LP). Participants performed bilateral scapular plane overhead movements before and after EBFB. EBFB consisted of 10 bilateral repetitions of I, W, T, and Y exercises focused on reducing UT and increasing LT and SA activity. Prior to EBFB, no significant difference in muscle activity was present between sides. A significant main effect of time indicated that after EBFB both sides exhibited reduced UT activity at 60° (p=0.003) and 90° (p=0.036), LT activity was increased at all measured humeral angles (p<0.0005), and SA muscle activity was increased at 110° (p=0.001). EBFB in conjunction with scapular based exercise effectively alters muscle activity of asymptomatic and symptomatic scapular musculature.

Reliability of Scapula Clinical Assessment and Effectiveness of Scapular-Focused Exercises in a Non-Athletic Population with Shoulder Pain a Literature Review

Introduction: The scapula is recognised as a key element of the proper functioning in the shoulder complex. Scapular movement abnormalities have been defined as scapular dyskinesis. It is treated as a dysfunction that increases the risk of shoulder pain. Various diagnostic and therapeutic methods have been introduced into clinical practice, the purpose of which are to assess the function of the scapula and restore normal movement patterns. The current state of knowledge does not allow to clearly answer the question as to whether the available tools applied for assessing the mobility and functions of the scapula are reliable and useful in clinical practice during diagnosis within the shoulder complex.

Comparison of the Effects of Isometric Horizontal Abduction on Shoulder Muscle Activity During Wall Push-Up Plus and Wall Slide in Individuals With Scapular Winging.

Wall push-up plus (WPP) and wall slide (WS) are commonly prescribed in early rehabilitation to increase serratus anterior (SA) muscle activity. For individuals with scapular winging (SW), synergistic muscles such as upper trapezius (UT) and pectoralis major (PM) may compensate for weak SA during scapular movement. However, no studies have applied isometric horizontal abduction (IHA) during WS in individuals with SW nor have compared it with WPP with IHA. This study compared the effects of IHA on shoulder muscle activity during WPP and WS exercises in individuals with SW. Cross-sectional study; 2-way repeated-measures analysis of variance was used to assess the statistical significance of observed differences in SA, UT, PM, lower trapezius (LT), and infraspinatus (IS) muscle activities. Research laboratory. We recruited 30 individuals with SW comprising 20 men and 10 women. The individuals performed WPP and WS exercises with and without IHA using Thera-Band. Surface electromyography was used to measure muscle activity of the SA, UT, PM, LT, and IS during the isometric phase of WPP and WS. Maximal voluntary isometric contractions were recorded to normalize electromyographic data. There was no significant interaction between IHA application and exercise type for any of the shoulder muscles. IHA application increased SA (P = .008), UT (P = .001), LT (P = .009), and IS (P = .000) activities and decreased PM (P = .001) activity compared with those without IHA. WS exercises elicited higher PM (P = .017) and LT (P = .011) activities than WPP. WPP and WS with IHA may be effective in increasing the muscle activities of shoulder stabilizers and preventing overactivation of PM activity. WPP may be recommended for individuals with overactivated PM, whereas WS may be used to increase LT activity.

Accuracy of measuring scapular position and motion with a novel motion capture system

Scapula kinematics is recognized to be a crucial variable in shoulder dysfunction. Nevertheless, quantitative scapula tracking and measurement are not part of the current clinical evaluation. The main concern is measurement accuracy. To assess the accuracy of the wearable sensor technology Showmotion a cadaver experiment was designed, allowing a direct comparison between sensors directly pinned to the scapula and superficial sensors. A measurement protocol was adopted to evaluate errors in measurement, mimicking the suggested invivo evaluation. Sensors were simultaneously placed above (supraspinal) and below (infraspinal) the scapular spine to determine if one placement resulted in fewer errors compared to the other. Mean and standard deviations of the supraspinal sensor root mean square error (RMSE) in flexion-extension movements resulted in 3.59° ± 2.36°, 4.73° ± 2.98°, and 6.26° ± 3.62° for upward-downward rotation (up-down), anterior-posterior tilt and internal-external (intra-extra) rotation, respectively, while 2.16° ± 1.21°, 2.20° ± 1.02°, and 4.46° ± 2.16° for the infraspinal sensor. In abduction-adduction movements, mean and standard deviations of the supraspinal sensor RMSE resulted in 4.26° ± 2.98°, 5.68° ± 4.22°, and 7.04° ± 4.36° for up-down rotation, anterior-posterior tilt, and intra-extra rotation, respectively, while 2.38° ± 1.63°, 2.47° ± 1.77°, and 4.92° ± 3.14° for the infraspinal sensor. The same behavior was confirmed in shrug movements, where 4.35° ± 3.24°, 4.63° ± 3.09°, and 5.34° ± 6.67° are mean and standard deviations of the supraspinal sensor RMSE for up-down rotation, anterior-posterior tilt, and intra-extra rotation, respectively, while 2.76° ± 1.87°, 2.83° ± 2.53°, and 4.68° ± 5.22° for the infraspinal sensor. This method of quantitative assessment of scapular motion is shown to have good accuracy and low error between the sensor measurements and actual bone movement in multiple planes of scapular motion, both over the entire range of motion and in its individual segment intervals. The decreased amount of error with the infraspinal sensor placement suggests that placement is ideal for clinical quantitative assessment of scapular motion.

Proximal to distal sequencing impacts on maximum shoulder joint angles and the risk of impingement in baseball pitching involving a scapular independent thoracohumeral model.

Hyperangulation of the scapulohumeral joint due to poor coordination of the scapula during throwing motion is claimed to be a major cause of internal impingement in baseball pitchers. However, evidence of injurious scapular kinematics is lacking, particularly regarding how hyperangularion actually occurs in full-effort pitching. The purpose of this study was to describe sequential scapular motions involved in attaining maximum joint angles during pitching and the implications for internal impingement in elite baseball pitchers. An electromagnetic goniometer system computed kinematics for pelvis, thorax, scapulae, arms, and forearms during baseball pitching in 72 pitchers. Internal impingement risk was assessed based on kinematic characteristics of internal impingement quantified in a cadaveric study. The pelvis, thorax, and scapula rotated in the proximal-to-distal sequence. Large forearm layback observed near the end of the cocking phase (182 ± 27°) was achieved with a submaximal scapulohumeral external rotation (98 ± 14°). In the next 0.027 ± 0.007 s, forward thoracic rotation and then scapular rotation caused increased scapulohumeral external rotation to a maximum of 113 ± 14°. Here, humeral horizontal adduction and scapula protraction occurred simultaneously preventing the humerus from lagging further behind the scapula. Only one participant reached critical hyperangulation beyond which internal impingement was reported to occur. Most elite pitchers safely attained the fully cocked position, yet off-timed recoiling of scapular protraction caused hyperangulation in full-effort pitching. Therefore, proximal-distal sequencing between the scapula and humerus should be evaluated to lessen the risk of internal impingement in baseball pitchers.