Glenohumeral Motion Research Articles

Acute effects of spinal bracing on scapular kinematics in adolescent idiopathic scoliosis

BackgroundBracing is the most common nonsurgical treatment for adolescent idiopathic scoliosis. Spinal braces affect glenohumeral and scapulothoracic motion because they restrict trunk movements. However, the potential spinal-bracing effects on scapular kinematics are unknown. The present study aimed to investigate the acute effects of spinal bracing on scapular kinematics in adolescent idiopathic scoliosis. MethodsScapular kinematics, including scapular internal/external rotation, posterior/anterior tilting, and downward/upward rotation during scapular plane elevation, were evaluated in 27 in-brace and out-of-brace adolescent idiopathic scoliosis patients with a three-dimensional electromagnetic tracking system. Data on the position and orientation of the scapula at 30°, 60°, 90°, and 120° humerothoracic elevation were used for statistical comparisons. The paired t-test was used to assess the differences between the mean values of in-brace and out-of-brace conditions. FindingsThe in-brace condition showed significantly increased (P<0.05) scapular anterior tilting and decreased internal rotation in the resting position on the convex and concave sides; increased scapular downward rotation at 120° humerothoracic elevation on the convex side and at 30°, 60°, 90°, and 120° humerothoracic elevation on the concave side; increased scapular anterior tilt at 30°, 60°, 90°, and 120° humerothoracic elevation on the convex and concave sides; and decreased (P<0.05) maximal humerothoracic elevation of the arm. InterpretationSpinal bracing affects scapular kinematics. Observed changes in scapular kinematics with brace may also affect upper extremity function for adolescents with idiopathic scoliosis. Therefore, clinicians should include assessments of the glenohumeral and scapulothoracic joints when designing rehabilitation protocols for patients with adolescent idiopathic scoliosis.

Shoulder position sense in volleyball players with infraspinatus atrophy secondary to suprascapular nerve neuropathy.

Isolated infraspinatus atrophy (IIA) is a common condition among overhead-activity athletes, which affects the hitting shoulder and is caused by suprascapular nerve injury. As the suprascapular nerve is a mixed nerve, such damage could lead to reduced afferent proprioceptive information and impaired shoulder sensorimotor control. This study aimed to evaluate the proprioception of the shoulder with IIA, through the assessment of shoulder position sense. The shoulder position sense was assessed in 24 professional volleyball players (12 players with IIA and 12 healthy players) with a blind dynamic shoulder repositioning test (all participants were blindfolded during the test). Three functional glenohumeral movements were tested as follows: abduction, forward flexion, and a combination of abduction and external rotation. In all three tested movements, the affected shoulder of players with isolated infraspinatus atrophy showed significantly higher hand position error than the healthy contralateral (P<10-3 , for all movements) and the healthy control group hitting shoulder (P<10-3 , for abduction and flexion; P=.02, for combined movement of abduction and external rotation). The study highlights a reduced sense of position of the hitting shoulder in professional volleyball players with IIA secondary to suprascapular nerve palsy. The higher hand position error of the pathologic shoulder suggests an impairment of the shoulder sensorimotor control system, which likely results from reduced afferent proprioceptive information. Deficient afferent proprioceptive information may result in poor accuracy in descending motor commands and impairment of the shoulder neuromuscular function, leading to reduced shoulder functional stability and increased risk of injury.

Kinematic analysis of the shoulder complex after anatomic and reverse total shoulder arthroplasty: A cross-sectional study

BackgroundThe movement of the arm relative to the trunk results from coordinated 3D glenohumeral and scapulothoracic movements. Changes in scapula kinematics may occur after total shoulder arthroplasty and could affect clinical and functional outcomes. ObjectivesTo assess the 3D movement of the scapula during arm elevation after anatomic and reverse total shoulder arthroplasty. Design/MethodsThis was a single-centre, non-randomized, controlled cross-sectional study. Patients with anatomic (n = 14) and reverse total shoulder arthroplasty (n = 9) were prospectively enrolled and were compared to age-matched asymptomatic controls (n = 23). 3D scapular kinematics were assessed by a non-invasive, electromagnetic method during arm abduction and flexion. 3D scapular rotations and 3D linear displacements of the barycentre (geometrical centre) at rest and at 30°, 60° and 90° arm elevation; as well as scapulohumeral rhythm were analysed. Participant groups were compared using one-way ANOVA and Bonferroni post-hoc testing for normally distributed data, and Mann–Whitney U test for non-normally distributed data. Results/FindingsTotal range of scapular lateral rotation and barycentre displacement were increased, and scapulohumeral rhythm was reduced, in patients with anatomic and reverse total shoulder arthroplasty compared with age-matched controls; however, the global scapular kinematic pattern was preserved. Conclusion/InterpretationFor patients after total shoulder arthroplasty, the increased contribution of the scapula to arm elevation is consistent with a compensatory mechanism for the reduced glenohumeral mobility. The stability of the global scapula kinematic pattern reflects its mechanical and neuromotor strength.

Humeral Retrotorsion and Glenohumeral Motion in Youth Baseball Players Compared With Age-Matched Nonthrowing Athletes

Background: Baseball players exhibit a more posteriorly oriented humeral head in their throwing arm. This is termed humeral retrotorsion (HRT) and likely represents a response to the stress of throwing. This adaptation is thought to occur while the athlete is skeletally immature, however currently there is limited research detailing how throwing activity in younger players influences the development of HRT. In addition, it is presently unclear how this changing osseous orientation may influence shoulder motion within young athletes. Purpose: To determine the influence of throwing activity and age on the development of side-to-side asymmetry in HRT and shoulder range of motion (ROM). Study Design: Cross-sectional study; Level of evidence, 3. Methods: Healthy athletes (age range, 8-14 years) were categorized into 2 groups based upon sports participation; throwers (n = 85) and nonthrowers (n = 68). Bilateral measurements of HRT, shoulder external rotation (ER), internal rotation (IR), and total range of motion (TROM) at 90° were performed using diagnostic ultrasound and a digital inclinometer. Side-to-side asymmetry (dominant minus nondominant side) in HRT and in shoulder ER, IR, and TROM were assessed. Statistical analysis was performed with 2-way analysis of variance and Pearson correlation coefficients. Results: Throwers demonstrated a larger degree of HRT on the dominant side, resulting in greater asymmetry compared with nonthrowers (8.7° vs 4.8°). Throwers demonstrated a gain of ER (5.1°), a loss of IR (6.0°), and no change in TROM when compared with the nondominant shoulder. Pairwise comparisons identified altered HRT and shoulder ROM in all age groups, including the youngest throwers (age range, 8-10.5 years). A positive correlation existed between HRT and ER ROM that was stronger in nonthrowers (r = 0.63) than in throwers (r = 0.23), while a negative correlation existed with IR that was stronger in throwers (r = −0.40) than in nonthrowers (r = −0.27). Conclusion: Throwing activity causes adaptive changes in HRT and shoulder ROM in youth baseball players at an early age. Other factors in addition to HRT influence shoulder motion within this population.

Influence of disruption of the acromioclavicular and coracoclavicular ligaments on glenohumeral motion: a kinematic evaluation.

BackgroundChanges to the integrity of the acromioclavicular (AC) joint impact scapulothoracic and clavicular kinematics. AC ligaments provide anterior-posterior stability, while the coracoclavicular (CC) ligaments provide superior-inferior stability and a restraint to scapular internal rotation. The purpose of this cadaveric study was to describe the effect of sequential AC and CC sectioning on glenohumeral (GH) kinematics during abduction (ABD) of the arm. We hypothesized that complete AC ligament insult would result in altered GH translation in the anterior-posterior plane during abduction, while subsequent sectioning of both CC ligaments would result in an increasing inferior shift in GH translation.MethodsSix cadaveric shoulders were studied to evaluate the impact of sequential sectioning of AC and CC ligaments on GH kinematics throughout an abduction motion in the coronal plane. Following an examination of the baseline, uninjured kinematics, the AC ligaments were then sectioned sequentially: (1) Anterior, (2) Inferior, (3) Posterior, and (4) Superior. Continued sectioning of CC ligamentous structures followed: the (5) trapezoid and then the (6) conoid ligaments. For each group, the GH translation and the area under the curve (AUC) were measured during abduction using an intact cadaveric shoulder. Total translation was calculated for each condition between ABD 30° and ABD 150° using the distance formula, and a univariate analysis was used to compare total translation for each axis during the different conditions.ResultsGH kinematics were not altered following sequential resection of the AC ligaments. Disruption of the trapezoid resulted in significant anterior and lateral displacement of the center of GH rotation. Sectioning the conoid ligament further increased the inferior shift in GH displacement.ConclusionA combined injury of the AC and CC ligaments significantly alters GH kinematics during abduction. Type III AC separations, result in a significant change in the shoulder’s motion and may warrant surgical reconstruction to restore normal function.

Est-ce que les exercices pendulaires selon Codman sont utiles ?

Introduction Codman's pendular shoulder exercises have been widely used for decades as means of passively mobilizing the glenohumeral (GH) joint while not compromising recently injured or repaired tissues. Neurophysiological studies have confirmed the largely passive nature of the exercises, but no studies have actually shown that the exercises result in true GH movement. The aim of this study was thus to quantify GH motion during pendular exercises using a patient-specific measurement technique combining medical imaging and motion capture. The hypothesis was that these exercises involved little if any GH motion at all. Methods Ten healthy volunteers without hyperlaxity were recruited for this study. Shoulder kinematics were analyzed based on a previously validated biomechanical model. During motion capture, participants were instructed to perform latero-medial, antero-posterior, and circular Codman pendular exercises. GH range of motion (ROM), scapulothoracic (ST) ROM, thoracohumeral (TH) ROM and overall amplitude of the performed exercises were calculated for each sequence. Linear regression analyses were carried out to establish an association between different components of shoulder motion. Results Mean overall exercise amplitude was 33.95 ± 10.16° (range: 21.1° to 56.39°) for latero-medial exercises, 32.47 ± 14.78° (range: 6.67° to 54.05°) for antero-posterior exercises and 21.56 ± 7.63° (range: 14.01° to 35.49°) for circular exercises. GH and ST involvement were minimal in all exercise types. Mean GH amplitudes ranged from 4.88° to 11.47°, mean ST amplitudes from 0.82° to 3.54° and mean TH amplitudes ranged from 8.62° to 25.93°. Linear regression analyses only showed moderate association of overall exercise amplitudes with TH amplitudes ( R = 0.68, P = 1.26E-6), while no association was observed with GH ( R = 0.33, P = 0.03) or ST amplitudes (adjusted R 2 = 0.34, P = 0.003). Conclusion This study demonstrates that Codman pendular exercises are mainly the result of truncal movement with only little involvement of the GH and ST joints. These exercises can therefore not be supported as an effective contribution to passive shoulder rehabilitation.

Relationship between Spinal Alignment and Glenohumeral Joint Elevation in Kyphotic Elderly Women

The purpose of this study was to evaluate the relationship between spine alignment and shoulder elevation in a kyphotic elderly population. Twenty-three consecutive female patients who underwent balloon kyphoplasty for spinal compression fractures without shoulder symptoms were examined (mean age, 76 ± 6.3 years). Thoracic kyphosis angle (TK), lumbar lordosis angle (LL), and pelvic tilt angle (PT) were measured on standing true lateral radiographs of the whole spine. The shoulder active range of motion with or without scapular fixation was measured in the sitting position. The University of California Los Angeles (UCLA) Shoulder Score was recorded as the functional evaluation. The total elevation angle was 128.9° ± 22°, the glenohumeral angle was 80.7° ± 10.9°, and the UCLA Shoulder Score was 32.4 ± 2.1. The TK was 36.7°, the LL was −29.1°, and the PT was 30.5°. The total elevation angle was significantly negatively correlated with LL. TK and PT were not significantly correlated with any parameter. The total shoulder elevation angle was limited in the kyphotic elderly women in this study, and kyphotic change appeared to interfere with spinal extension and reduced the total elevation arc with no glenohumeral motion deficit. A reduction in total shoulder elevation was negatively correlated with LL.

Scapulothoracic and Glenohumeral Motions During Functional Reaching Tasks in Women With a History of Breast Cancer and Healthy Age-Matched Controls

Purposes: (1) To determine differences in scapulothoracic (ST) and glenohumeral (GH) motions between women with and without breast cancer (BrCa); and (2) to determine association between ST and GH motions and shoulder pain and disability. Methods: Thirty women with BrCa and 30 women without BrCa participated in this observational study. ST and GH kinematic data were collected during 5 repetitions of unilateral unweighted overhead reaching, weighted overhead reaching (0.91 kg), and simulated hair combing in a research laboratory. The involved side in women with BrCa was matched by hand dominance with the appropriate side in women without BrCa. Shoulder pain and disability were measured using the Penn Shoulder Score. Separate 1-way multivariate analysis of variance tests were conducted to determine whether differences existed. Pearson correlations were used to determine association between ST and GH motions and shoulder pain and disability. Significance levels were set at .05. Results: There were no significant differences in ST and GH motions between women with and without BrCa. Specific ST and GH motions were significantly correlated (r = 0.36-0.57) with shoulder pain and disability. Conclusion: Lack of significant differences in ST and GH motions suggests that the majority of women with BrCa in our study had sufficient motion to accomplish the functional tasks. Several ST and GH motions were weakly to moderately associated with shoulder pain and disability among women with BrCa. However, it is not clear whether these ST and GH motions are compensatory strategies or contributing factors to the development of shoulder pain and disability.

The effect of the arthroscopic augmentation of the subscapularis tendon on shoulder instability and range of motion: A biomechanical study

BackgroundAnterior shoulder dislocation is common. The treatment of recurrence with glenoid bone defect is still considered controversial. A new arthroscopic subscapularis augmentation has recently been described that functions to decrease the anterior translation of the humeral head. The purpose of the presented study was to examine the biomechanical effect on glenohumeral joint motion and stability. MethodsEight fresh frozen cadaver shoulders were studied by use of a force guided industrial robot fitted with a six-component force-moment sensor to which the humerus was attached. The testing protocol includes measurement of glenohumeral translation in the anterior, anterior-inferior and inferior directions at 0°, 30° and 60° of glenohumeral abduction, respectively, with a passive humerus load of 30N in the testing direction. The maximum possible external rotation was measured at each abduction angle applying a moment of 1Nm. Each specimen was measured in a physiologic state, as well as after Bankart lesion with an anterior bone defect of 15–20% of the glenoid, after arthroscopic subscapularis augmentation and after Bankart repair. FindingsThe arthroscopic subscapularis augmentation decreased the anterior and anterior-inferior translation. The Bankart repair did not restore the mechanical stability compared to the physiologic shoulder group. External rotation was decreased after arthroscopic subscapularis augmentation compared to the physiologic state, however, the limitation of external rotation was decreased at 60° abduction. InterpretationThe arthroscopic subscapularis augmentation investigated herein was observed to restore shoulder stability in an experimental model.

Surgical treatment of anterosuperior impingement of the shoulder

Therapy of intraarticular lesions and elimination of structural risk factors for those suffering from clinical manifest anterosuperiorer impingement (ASI) of the shoulder. This includes as a maximum version the arthroscopic repair of supraspinatus (SST) and subscapularis tendon (SCT) tears with subsequent subpectoral tenodesis of the long head of the biceps tendon (LBT) and arthroscopic coracoplasty. Clinical manifest anterosuperiorer impingement of the shoulder with anterior shoulder pain, failed conservative treatment and clear intraarticular damage in radiological imaging. This involves in detail lesions of the SST, SCT and damage to the LBT. Lack of structural intraarticular lesions or massive osteoarthritis. Persistent dysfunction of active and passive glenohumeral and scapulathoracal motion, due to neurologic deficits or stiff shoulder. A hypertrophic or deformed healed coracoid process is seen as a structural risk factor for suffering from ASI and should be addressed surgically when causing impingement. Arthroscopic tenotomy of the LBT with subsequent repair of the SST and SCT. Arthroscopic coracoplasty if indicated and subpectoral tenodesis of the long head of the biceps. No biceps activity and intermittent immobilization in sling for 6weeks. Limitation of abduction, flexion and external rotation for 6weeks depending on rotator cuff tendon repair. Start of sport-specific training after 3months, over-head sports 6months postoperatively. The arthroscopic repair of anterosuperior rotator cuff tears provides reliable results for improvement in function, decreases in pain and improvement in shoulder scores. The overall rate of adverse events is low.

Arthroscopic Rotator Cuff Repair With Concomitant Capsular Release

Patients with rotator cuff tears may present with or subsequently develop concomitant shoulder stiffness. The treatment of rotator cuff tears in the face of passive glenohumeral motion loss is controversial. Preoperative shoulder stiffness has been considered by some a contraindication to rotator cuff repair. Some surgeons recommend staging surgical procedures and delaying rotator cuff repair until shoulder stiffness has resolved. However, this can lead to prolonged recovery times and patient dissatisfaction. We describe a surgical technique that allows for the single-stage arthroscopic management of rotator cuff tears with associated adhesive capsulitis. Arthroscopic capsular release and shoulder manipulation are performed in the same operative setting as arthroscopic rotator cuff repair. We have found that this combined, single-stage arthroscopic approach can effectively treat patients with rotator cuff tears and concomitant shoulder stiffness.

Scapula behavior associates with fast sprinting in first accelerated running.

The arm-swing motion is important for coordinated lower limb movement during a fast sprint and is composed of three-dimensional scapulothoracic and glenohumeral joint motion. Here, we aimed to clarify the role of the scapula during the initiation of a sprint running when sprinter run with high horizontal acceleration. Ten sports-active students participated in four 5-m dashes, with scapular constraint using non-elastic therapy tape (constraint condition) and without scapular constraint (free condition). The sprinting kinematics was assessed by a 16-camera motion capture system. In the constraint condition, the 2-m sprint time was significantly longer than that in the free condition. At the instants of foot-contact and take-off during the first step, no significant difference in the humerothoracic flexion angle was seen between these two conditions. In contrast, at the instants of foot-contact and take-off during the first step, the humerothoracic extension angle in the constraint condition was significantly smaller than that in the free condition. The forward leaning vector angle of center of mass during the first step was significantly greater than that in the constraint condition. Although no significant difference in hip extension and foot forward leaning angles was seen at the instant of foot contact during the first step between the two conditions, at the instant of take-off, the hip extension and foot forward leaning angles in the constraint condition were significantly smaller than those in the free condition. Therefore, scapular behavior in first accelerated running contributes to larger upper- and lower-limb motions and facilitates coordinating whole-body balance for a fast sprint.

Double-Row Capsulolabral Repair Increases Load to Failure and Decreases Excessive Motion

Using a cadaver shoulder instability model and load-testing device, we compared biomechanical characteristics of double-row and single-row capsulolabral repairs. We hypothesized a greater reduction in glenohumeral motion and translation and a higher load to failure in a mattress double-row capsulolabral repair than in a single-row repair. In 6 matched pairs of cadaveric shoulders, a capsulolabral injury was created. One shoulder was repaired with a single-row technique, and the other with a double-row mattress technique. Rotational range of motion, anterior-inferior translation, and humeral head kinematics were measured. Load-to-failure testing measured stiffness, yield load, deformation at yield load, energy absorbed at yield load, load to failure, deformation at ultimate load, and energy absorbed at ultimate load. Double-row repair significantly decreased external rotation and total range of motion compared with single-row repair. Both repairs decreased anterior-inferior translation compared with the capsulolabral-injured condition, however, no differences existed between repair types. Yield load in the single-row group was 171.3 ± 110.1N, and in the double-row group it was 216.1 ± 83.1N(P= .02). Ultimate load to failure in the single-row group was 224.5 ± 121.0N, and in the double-row group it was 373.9 ± 172.0N(P= .05). Energy absorbed at ultimate load in the single-row group was 1,745.4 ± 1,462.9 N-mm, and in the double-row group it was 4,649.8 ± 1,930.8 N-mm (P= .02). In cases of capsulolabral disruption, double-row repair techniques may result in decreased shoulder rotational range of motion and improved load-to-failure characteristics. In cases of capsulolabral disruption, repair techniques with double-row mattress repair may provide more secure fixation. Double-row capsulolabral repair decreases shoulder motion and increases load to failure, yield load, and energy absorbed at yield load more than single-row repair.

Scapulohumeral rhythm relative to active range of motion in patients with symptomatic rotator cuff tears

Some patients with rotator cuff tears feel pain without functional limitation, whereas others show a decrease in range of motion. To investigate this distinction, the scapulohumeral rhythm was used to conduct a functional evaluation of shoulder joints' coordination. The objective was to characterize patients according to their active range of motion without pain and their scapulohumeral rhythm compared with healthy individuals. Fourteen patients with rotator cuff tears and 14 healthy individuals were set up with 35 reflective markers on the trunk and upper limb tracked by an optoelectronic system to measure the scapulohumeral rhythm. Five scapular plane maximal arm elevations were executed without pain. Patients were separated by maximal arm elevation of 85° (category A) and 40° (category B). Three-way mixed-design analysis of variance with factors of group (patients and healthy), arm elevation, and motion direction was applied to the scapulohumeral rhythm. A main effect of group (P = .032) was observed in patients in category A, who showed inferior scapulohumeral rhythm. An interaction between group and arm elevation (P = .044) was observed for patients in category B, where their scapulohumeral rhythm increased more during arm elevation than in the healthy individuals. Patients who reached at least 85° compensated for the loss of glenohumeral motion by increased scapulothoracic contribution, suggesting that structural damage interferes with motion mechanics. In contrast, patients who reached less range of motion underused the scapulothoracic joint, which is likely to create subacromial impingement at low arm elevation. A patient's maximal range of motion without pain may indicate a pattern of scapulohumeral rhythm alteration.

A bi-articular model for scapular-humeral rhythm reconstruction through data from wearable sensors.

BackgroundPatient-specific performance assessment of arm movements in daily life activities is fundamental for neurological rehabilitation therapy. In most applications, the shoulder movement is simplified through a socket-ball joint, neglecting the movement of the scapular-thoracic complex. This may lead to significant errors. We propose an innovative bi-articular model of the human shoulder for estimating the position of the hand in relation to the sternum. The model takes into account both the scapular-toracic and gleno-humeral movements and their ratio governed by the scapular-humeral rhythm, fusing the information of inertial and textile-based strain sensors.MethodTo feed the reconstruction algorithm based on the bi-articular model, an ad-hoc sensing shirt was developed. The shirt was equipped with two inertial measurement units (IMUs) and an integrated textile strain sensor. We built the bi-articular model starting from the data obtained in two planar movements (arm abduction and flexion in the sagittal plane) and analysing the error between the reference data - measured through an optical reference system - and the socket-ball approximation of the shoulder. The 3D model was developed by extending the behaviour of the kinematic chain revealed in the planar trajectories through a parameter identification that takes into account the body structure of the subject.ResultThe bi-articular model was evaluated in five subjects in comparison with the optical reference system. The errors were computed in terms of distance between the reference position of the trochlea (end-effector) and the correspondent model estimation. The introduced method remarkably improved the estimation of the position of the trochlea (and consequently the estimation of the hand position during reaching activities) reducing position errors from 11.5 cm to 1.8 cm.ConclusionThanks to the developed bi-articular model, we demonstrated a reliable estimation of the upper arm kinematics with a minimal sensing system suitable for daily life monitoring of recovery.

The Shoulder at Risk: Scapular Dyskinesis and Altered Glenohumeral Rotation

The shoulder at risk is a concept that describes alterations in the kinetic chain (the sequential coordinated and task-specific development of force) and shoulder that produce an impairment of optimum function. The glenohumeral (GH) structures may be susceptible to injury when exposed to the inherent high demands of throwing, creating the disabled throwing shoulder. Although multiple factors can lead to a shoulder at risk, the 2 most common factors are scapular dyskinesis and alterations in GH motion. Dyskinesis represents an alteration of static scapular position or dynamic scapular motion in coordination with arm motion and is best considered an impairment of optimum shoulder function, with potential harmful effects on the anatomical structures. Altered GH rotation creates a shoulder at risk by decreasing the rotation and increasing the amount of translation. Both impairments are capable of altering shoulder motions and loads and should be considered contributors to the shoulder at risk of injury. A focalized physical examination should be utilized to not only initially assess for the presence or absence of these impairments but also periodically assess throughout training or competition as both impairments can develop overtime even in the absence of injury.

The effect of the rotator interval on glenohumeral kinematics during abduction.

BackgroundThe rotator interval (RI) has been exploited as a potentially benign point of entry into the glenohumeral (GH) joint. Bounded by the supraspinatus, subscapularis and coracoid process of the scapula, the RI is believed to be important in the shoulder’s soft tissue balancing and function. However, the role of the RI in shoulder kinematics is not fully understood. The purpose of this study is to describe the effect of the RI on GH motion during abduction of the arm.MethodsSix shoulders from three cadaveric torsos were studied to assess the impact of changes in the RI during abduction under four conditions: Intact (Baseline), Opened, Repaired (repaired with side-to-side tissue approximation, no overlap) and Tightened (repaired with 1 cm overlap). For each group, the GH translation and area under the Curve (AUC) were measured during abduction using an intact cadaveric shoulder (intact torso).ResultsGH kinematics varied in response to each intervention and throughout the entire abduction arc. Opening the RI caused a significant change in GH translation. The Repair and Tightened groups behaved similarly along all axes of GH motion.ConclusionsThe RI is central to normal GH kinematics. Any insult to the tissue’s integrity alters the shoulder’s motion throughout abduction. In this model, closing the RI side-to-side has the same effect as tightening the RI. Since suture closure may offer the same benefit as tightening the RI, clinicians should consider this effect when treating patients with shoulder laxity. This investigation provides an improved perspective on the role of the RI on GH kinematics during abduction. When managing shoulder pathology, surgeons should consider how these different methods of RI closure affect the joint’s motion. In different circumstances, the surgical approach to the RI can be tailored to address each patient’s specific needs.

Three-Dimensional Scapular Kinematics in Patients with Reverse Total Shoulder Arthroplasty during Arm Motion.

BackgroundThere have been few reports on altered kinematics of the shoulder after reverse total shoulder arthroplasty (RTSA). We investigated differences in 3-dimensional (3D) scapular motions assessed using an optical tracking system between RTSA treated shoulders and asymptomatic contralateral shoulders during arm motion.MethodsThirteen patients who underwent RTSA were assessed for active arm elevation in 2 distinct elevation planes (sagittal plane flexion and scapular plane abduction). Their mean age was 72 years (range, 69 to 79 years) and the mean follow-up was 24.4 months (range, 13 to 48 months). The dominant side was the right side in all the 13 patients, and it was also the side treated with RTSA. Scapular kinematics was recorded with an optical tracking system. The scapular kinematics and the scapulohumeral rhythm (SHR) of the RTSA shoulders and asymptomatic contralateral shoulders were recorded and analyzed during arm elevation.ResultsThere were no significant differences in internal/external rotation and anterior/posterior tilting of the scapula between shoulders during arm motion (p > 0.05). However, upward rotation of the scapula differed significantly during arm motion (p = 0.035 for sagittal plane flexion; p = 0.046 for scapular plane abduction). There were significant differences in the SHR between the two shoulders (p = 0.016 for sagittal plane flexion; p = 0.021 for scapular plane abduction).ConclusionsThe shoulder kinematics after RTSA showed significant differences from the contralateral asymptomatic shoulders. Increased upward rotation and decreased SHR after RTSA indicate that RTSA shoulders use more scapulothoracic motion and less glenohumeral motion to elevate the arm.

Definition of anatomical zero positions for assessing shoulder pose with 3D motion capture during bilateral abduction of the arms.

BackgroundSurgical interventions at the shoulder may alter function of the shoulder complex. Clinically, the outcome can be assessed by universal goniometry. Marker-based motion capture may not resemble these results due to differing angle definitions.MethodsThe clinical inspection of bilateral arm abduction for assessing shoulder dysfunction is performed with a marker based 3D optical measurement method. An anatomical zero position of shoulder pose is proposed to determine absolute angles according to the Neutral-0-Method as used in orthopedic context. Static shoulder positions are documented simultaneously by 3D marker tracking and universal goniometry in 8 young and healthy volunteers. Repetitive bilateral arm abduction movements of at least 150° range of motion are monitored. Similarly a subject with gleno-humeral osteoarthritis is monitored for demonstrating the feasibility of the method and to illustrate possible shoulder dysfunction effects.ResultsWith mean differences of less than 2°, the proposed anatomical zero position results in good agreement between shoulder elevation/depression angles determined by 3D marker tracking and by universal goniometry in static positions. Lesser agreement is found for shoulder pro-/retraction with systematic deviations of up to 6°. In the bilateral arm abduction movements the volunteers perform a common and specific pattern in clavicula-thoracic and gleno-humeral motion with maximum shoulder angles of 32° elevation, 5° depression and 45° protraction, respectively, whereas retraction is hardly reached. Further, they all show relevant out of (frontal) plane motion with anteversion angles of 30° in overhead position (maximum abduction). With increasing arm anteversion the shoulder is increasingly retroverted, with a maximum of 20° retroversion. The subject with gleno-humeral osteoarthritis shows overall less shoulder abduction range of motion but with increased out-of-plane movement during abduction.ConclusionsThe proposed anatomical zero definition for shoulder pose fills the missing link for determining absolute joint angles for shoulder elevation/depression and pro-/retraction. For elevation-/depression the accuracy suits clinical expectations very well with mean differences less than 2° and limits of agreement of 8.6° whereas for pro-/retraction the accuracy in individual cases may be inferior with limits of agreement of up to 24.6°. This has critically to be kept in mind when applying this concept to shoulder intervention studies.

Scapular Resting Position and Gleno-Humeral Movement Dysfunction in Asymptomatic Racquet Players: A Case-Control Study.

Background:Racquet sports, especially lawn tennis and badminton have been gaining popularity in Asian countries like India. With this increase in popularity, the injury rate in the sport has also increased.Objectives:The study will help detect the presence of gleno-humeral movement dysfunction and scapular resting position abnormality in asymptomatic racquet players, thus providing basis for screening the players and allow the clinician to determine if the asymmetry is a normal adaptation in the player or an abnormal change associated with injury.Materials and Methods:46 asymptomatic professional players were divided into a study group of 23 players (16 tennis and 7 badminton) and control group of 23 football players. Assessment of passive gleno-humeral range of motion and distance of spine and inferior angle of scapula from corresponding spinous process were measured bilaterally and between groups.Results:There was statistically significant reduction in range of internal rotation (62.17 ± 8.09), extension (39.78 ± 4.12) and an increase in the external rotation (106.95 ± 7.49) of dominant compared to non-dominant arm of racquet players and a statistically significant decrease in internal rotation (78.69 ± 10.24), extension (44.78 ± 3.19), adduction (37.39 ± 6.54) and an increase in external rotation (102.6 ± 5.19) of dominant arm of racquet players compared to football players. Study also showed statistically significant increase in the spino-scapular distance at the level of inferior angle of scapula (10.23 ± 1.43) on dominant side compared to non-dominant.Conclusions:The dominant side scapula of asymptomatic racquet players showed increased external rotation and elevation as compared to the non-dominant side. Also, reduced shoulder internal rotation, extension and adduction and gain in shoulder external rotation was observed on the dominant side of racquet players when compared to the control group.