Stephanie A. Russo

Scapulothoracic and glenohumeral contributions to motion in children with brachial plexus birth palsy

BACKGROUND Brachial plexus birth palsy occurs in 0.4 to 4.6 of every 1000 live births, with residual shoulder dysfunction in approximately one third of cases. Clinical measures, such as the Mallet classification, provide no insight into the scapulothoracic and glenohumeral contributions to tested global shoulder movements. This study describes the scapulothoracic and glenohumeral components of shoulder motion during the modified Mallet test. METHODS Twelve children with Erbs palsy (C5-6) and 8 children with extended Erbs palsy (C5-7) were recruited. The unaffected limbs of 6 subjects were also tested. Locations of markers placed on the thorax, humerus, and scapula were recorded in a neutral position and each of the modified Mallet positions. Scapulothoracic, glenohumeral, and humerothoracic helical displacements and acromion process linear displacements were compared between groups. RESULTS The brachial plexus birth palsy groups exhibited significantly smaller glenohumeral displacements in all modified Mallet positions and significantly larger scapulothoracic displacements in the global external rotation and hand to mouth positions. Discriminant function analysis using only humerothoracic variables correctly classified 76.9% of subjects. Discriminant function analysis incorporating scapulothoracic, glenohumeral, and acromion process displacement variables produced accuracy of 92.6%. CONCLUSIONS Children with brachial plexus birth palsy demonstrated decreased glenohumeral contributions to achieve every modified Mallet position and increased scapulothoracic contribution in two positions compared with the unaffected group. Different scapulothoracic and glenohumeral strategies were identified between groups. Finally, scapulothoracic and glenohumeral components of shoulder motion are more specific than humerothoracic measures to diagnostic classification.

Evaluating the acromion marker cluster as a method for measuring scapular orientation in children with brachial plexus birth palsy.

Several studies have described using an acromion marker cluster for measuring scapular orientation in healthy adults performing planar motions. It is unknown whether the acromion marker cluster method will provide the same level of accuracy in children with brachial plexus birth palsy. This study compared this method to palpation for calculating scapular orientation in children with brachial plexus birth palsy performing clinically relevant movements. Scapular orientation in ten patients was determined by palpation and an acromion marker cluster in neutral and six Modified Mallet positions. RMSEs and mean relative errors were calculated. Resultant RMSEs ranged from 5.2 degrees to 21.4 degrees. The averages of the mean relative errors across all positions for each axis were 177.4% for upward/downward rotation, 865.0% for internal/external rotation, and 166.2% for anterior/posterior tilt. The acromion marker cluster method did not accurately measure scapular rotation relative to the total movement on an individual or group basis in the population. With most relative errors over 100%, the acromion marker cluster method often produced errors larger than the actual measured motion. The accuracy of the acromion marker cluster method limits its use as a clinical tool for measuring scapular kinematics on children with brachial plexus birth palsy.

Limited glenohumeral cross-body adduction in children with brachial plexus birth palsy: a contributor to scapular winging.

Background: Approximately 1 of every 1000 live births results in life-long impairments because of a brachial plexus injury. The long-term sequelae of persistent injuries include glenohumeral joint dysplasia and glenohumeral internal rotation and adduction contractures. Scapular winging is also common, and patients and their families often express concern regarding this observed scapular winging. It is difficult for clinicians to adequately address these concerns without a satisfying explanation for why scapular winging occurs in children with brachial plexus birth palsy. This study examined our proposed theory that a glenohumeral cross-body abduction contracture leads to the appearance of scapular winging in children with residual brachial plexus birth palsy. Methods: Sixteen children with brachial plexus injuries were enrolled in this study. Three-dimensional locations of markers placed on the thorax, scapula, and humerus were recorded in the hand to mouth Mallet position. The unaffected limbs served as a control. Scapulothoracic and glenohumeral cross-body adduction angles were compared between the affected and unaffected limbs. Results: The affected limbs demonstrated significantly greater scapulothoracic and significantly smaller glenohumeral cross-body adduction angles than the unaffected limbs. The affected limbs also exhibited a significantly lower glenohumeral cross-body adduction to scapulothoracic cross-body adduction ratio. Conclusions: The results of this study support the theory that brachial plexus injuries can lead to a glenohumeral cross-body abduction contracture. Affected children demonstrated increased scapulothoracic cross-body adduction that is likely a compensatory mechanism because of decreased glenohumeral cross-body adduction. These findings are unique and better define the etiology of scapular winging in children with brachial plexus injuries. This information can be relayed to patients and their families when explaining the appearance of scapular winging. Level of Evidence: Level II.

Identification of scapular kinematics using surface mapping: a validation study.

The immediate goal of this study was to develop and validate a noninvasive, computational surface mapping approach for measuring scapular kinematics by using available motion capture technology in an innovative manner. The long-term goal is to facilitate clinical determination of the role of the scapula in children with brachial plexus birth palsy (BPBP). The population for this study consisted of fourteen healthy adults with prominent scapulae. Subject-specific scapular templates were created using the coordinates of five scapular landmarks obtained from palpation with subjects seated and arms relaxed in a neutral position. The scapular landmarks were re-palpated and their locations recorded in the six arm positions of the modified Mallet classification. The six Mallet positions were repeated with approximately 300 markers covering the scapula. The markers formed a surface map covering the tissue over the scapula. The scapular template created in the neutral position was iteratively fit to the surface map of each trial, providing an estimate of the orientation of the scapula. These estimates of scapular orientation were compared to the known scapular orientation determined from the scapular landmarks palpated in each Mallet position. The magnitude of the largest mean difference about an anatomical axis between the two measures of scapular orientation was 3.8° with an RMS error of 5.9°. This technique is practical for populations with visibly prominent scapulae (e.g., BPBP patients), for which it is a viable alternative to existing clinical methods with comparable accuracy.

Therapeutic Taping for Scapular Stabilization in Children With Brachial Plexus Birth Palsy

OBJECTIVE In this study, we aimed to assess whether therapeutic taping for scapular stabilization affected scapulothoracic, glenohumeral, and humerothoracic joint function in children with brachial plexus birth palsy and scapular winging. METHOD Motion capture data were collected with and without therapeutic taping to assist the middle and lower trapezius in seven positions for 26 children. Data were compared with one-way multivariate analyses of variance. RESULTS With therapeutic taping, scapular winging decreased considerably in all positions except abduction. Additionally, there were increased glenohumeral cross-body adduction and internal rotation angles in four positions. The only change in humerothoracic function was an increase of 3° of external rotation in the external rotation position. CONCLUSION Therapeutic taping for scapular stabilization resulted in a small but statistically significant decrease in scapular winging. Overall performance of positions was largely unchanged. The increased glenohumeral joint angles with therapeutic taping may be beneficial for joint development; however, the long-term impact remains unknown.

Scapular Stabilization Limits Glenohumeral Stretching in Children With Brachial Plexus Injuries

PURPOSE To quantify the effects of scapular stabilization on scapulothoracic and glenohumeral (GH) stretching. METHODS Motion capture data during external rotation and abduction with and without scapular stabilization were collected and analyzed for 26 children with brachial plexus birth palsy. These positions were performed by an experienced occupational therapist and by the childs caretaker. Scapulothoracic and GH joint angular displacements were compared between stretches with no stabilization, stabilization performed by the therapist, and stabilization performed by the caretaker. The relationship between the age and ability of the therapist and caretaker to perform the stretches with scapular stabilization was also assessed. RESULTS During external rotation there were no significant differences in either the scapulothoracic or GH joint during stabilization by either the therapist or the caretaker. During abduction, both scapulothoracic and GH joint angular displacements were statistically different. Scapulothoracic upward rotation angular displacement significantly decreased with scapular stabilization by the therapist and caretaker. Glenohumeral elevation angular displacement significantly decreased with scapular stabilization performed by the therapist and caretaker. There were only weak correlations between age and the differences in scapulothoracic and GH joint angular displacement performed by both the therapist and the caretaker. CONCLUSIONS The findings of this study indicate that scapular stabilization may be detrimental to passive stretching of the GH joint in children, as demonstrated by a reduced stretch. Based on the findings of this study, we have changed our practice to recommend passive stretches without scapular stabilization for children aged 5 years and older with brachial plexus birth palsy. In infants and children aged less than 5 years, we now recommend stretching with and without scapular stabilization until the effect of scapular stabilization is objectively assessed in these age groups. LEVEL OF EVIDENCE/TYPE OF STUDY Therapeutic IV.

Efficacy of 3 therapeutic taping configurations for children with brachial plexus birth palsy

Study Design: Cross‐sectional clinical measurement study. Introduction: Scapular winging is a frequent complaint among children with brachial plexus birth palsy (BPBP). Therapeutic taping for scapular stabilization has been reported to decrease scapular winging. Purpose of the Study: This study aimed to determine which therapeutic taping construct was most effective for children with BPBP. Methods: Twenty‐eight children with BPBP participated in motion capture assessment with 4 taping conditions: (1) no tape, (2) facilitation of rhomboid major and rhomboid minor, (3) facilitation of middle and lower trapezius, and (4) facilitation of rhomboid major, rhomboid minor, and middle and lower trapezius (combination of both 2 and 3, referred to as combined taping). The participants held their arms in 4 positions: (1) neutral with arms by their sides, (2) hand to mouth, (3) hand to belly, and (4) maximum crossbody adduction (CBA). The scapulothoracic, glenohumeral and humerothoracic (HT) joint angles and joint angular displacements were compared using multivariate analyses of variance with Bonferroni corrections. Results: Scapular winging was significantly decreased in both the trapezius and combined taping conditions in all positions compared with no tape. Rhomboids taping had no effect. Combined taping reduced HT CBA in the CBA position. Conclusions: Rhomboid taping cannot be recommended for treatment of children with BPBP. Both trapezius and combined taping approaches reduced scapular winging, but HT CBA was limited with combined taping. Therefore, therapeutic taping of middle and lower trapezius was the most effective configuration for scapular stabilization in children with BPBP. Resting posture improved, but performance of the positions was not significantly improved. Level of Evidence: Level II.

A comparison of two non-invasive methods for measuring scapular orientation in functional positions

Identification of scapular dyskinesis and evaluation of interventions depend on the ability to properly measure scapulothoracic (ST) motion. The most widely used measurement approach is the acromion marker cluster (AMC), which can yield large errors in extreme humeral elevation and can be inaccurate in children and patient populations. Recently, an individualized regression approach has been proposed as an alternative to the AMC. This technique utilizes the relationship between ST orientation, humerothoracic orientation and acromion process position derived from calibration positions to predict dynamic ST orientations from humerothoracic and acromion process measures during motion. These individualized regressions demonstrated promising results for healthy adults; however, this method had not yet been compared to the more conventional AMC. This study compared ST orientation estimates by the AMC and regression approaches to static ST angles determined by surface markers placed on palpated landmarks in typically developing adolescents performing functional tasks. Both approaches produced errors within the range reported in the literature for skin-based scapular measurement techniques. The performance of the regression approach suffered when applied to positions outside of the range of motion in the set of calibration positions. The AMC significantly underestimated ST internal rotation across all positions and overestimated posterior tilt in some positions. Overall, root mean square errors for the regression approach were smaller than the AMC for every position across all axes of ST motion. Accordingly, we recommend the regression approach as a suitable technique for measuring ST kinematics in functional motion.

Errors Associated With Utilizing Prescribed Scapular Kinematics to Estimate Unconstrained, Natural Upper Extremity Motion in Musculoskeletal Modeling

Musculoskeletal modeling is capable of estimating physiological parameters that cannot be directly measured, however, the validity of the results must be assessed. Several models utilize a scapular rhythm to prescribe kinematics, yet it is unknown how well they replicate natural scapular motion. This study evaluated kinematic errors associated with a model that employs a scapular rhythm using 2 shoulder movements: abduction and forward reach. Two versions of the model were tested: the original MoBL ARMS model that utilizes a scapular rhythm, and a modified MoBL ARMS model that permits unconstrained scapular motion. Model estimates were compared against scapulothoracic kinematics directly measured from motion capture. Three-dimensional scapulothoracic resultant angle errors associated with the rhythm model were greater than 10° for abduction (mean: 16.4°, max: 22.4°) and forward reach (mean: 11.1°, max: 16.5°). Errors generally increased with humerothoracic elevation with all subjects reporting greater than 10° differences at elevations greater than 45°. Errors associated with the unconstrained model were less than 10°. Consequently, use of the original MoBL ARMS model is cautioned for applications requiring precise scapulothoracic kinematics. These findings can help determine which research questions are suitable for investigation with these models and assist in contextualizing model results.