Collegiate baseball pitchers demonstrate a relationship between ball velocity and elbow varus torque, both within and across pitchers

High elbow varus torque during baseball pitching has been identified as a potential cause of ulnar collateral ligament injury in baseball pitchers. In general, elbow varus torque increases as ball velocity increases across pitchers. However, studies incorporating within-subject analyses report that not all professional pitchers have a positive relationship between elbow varus torque and ball velocity (T-V relationship). It remains unknown whether collegiate pitchers show the same trend as professionals in their T-V relationships. The current study investigated the T-V relationship of collegiate pitchers focusing on both across and within pitchers. Division 1 collegiate pitchers (n = 81) were assessed for elbow torque and ball velocity during pitching. Both across- and within-pitcher T-V relationships were significant (p < 0.05) using linear regression. However, more variance in elbow varus torque was explained using the within-pitcher relationship (R2 = 0.29) than the across-pitcher relationship (R2 = 0.05). Of the 81 pitchers, nearly half (n = 39) had significant T-V relationships, while the other half (n = 42) did not. Our findings indicate that the T-V relationship should be assessed on an individual basis as T-V is pitcher-specific.

Physiotherapists’ use and perspectives on the importance of patient-reported outcome measures for shoulder dysfunction

Background:

Many patient-reported outcome measures (PROs) for shoulder dysfunctions have acceptable psychometric properties. However, the large number of measures that are available present clinicians and researchers with dilemmas in PRO selection. This study set out to determine the perceived importance of PROs, the measures currently used by physiotherapists in clinical practice and research, and the psychometric criteria that are considered important in PRO selection.

Methods:

Delegates at the 2010 International Congress of Shoulder and Elbow Therapists were invited to participate in this cross-sectional observational study. Research Electronic Data Capture (REDCap) web-based tools were used to design an online questionnaire. IRB approval was gained prior to commencement of the study. Anonymised numerical survey data were tallied and frequency counts reported descriptively.

Results:

Participants submitted 101 completed questionnaires, which was an 84% response rate. One or more validated shoulder or upper extremity PROs were used by 91% of clinicians, and 94% of researchers. The use of PROs was considered to be ‘extremely’ or ‘very’ important by the majority of clinicians (76%), and researchers (98%). Most commonly used as a primary outcome by clinicians and researchers respectively were: the Disabilities of the Arm Shoulder Hand Questionnaire (DASH) (40%, 44%) and the Oxford Shoulder Scale (OSS) (36%, 22%); and as secondary outcomes: the DASH (33%, 28%); OSS (17%, 8%), the Shoulder Pain and Disability Index (SPADI) (8%, 18%); and the American Shoulder and Elbow Surgeons standardized assessment form (ASES) (8%, 13%). Psychometric properties and practicality aspects were deemed extremely or very important by 86–96% of participants.

Conclusion:

The majority of clinicians and researchers use a shoulder or upper extremity function or disability questionnaire. This indicates that PROs are considered important in clinical practice and research, and psychometric properties are critical in PRO selection. The DASH, OSS, SPADI and ASES are most commonly used by shoulder therapists in clinical practice and research studies.

Implications:

These findings can be used to aid the development of a consensus on a core set of PROs for shoulder dysfunctions for use by clinicians and researchers.

Direct 3-dimensional measurement of scapular kinematics during dynamic movements in vivo

The purpose of this study was to describe 3-dimensional scapular motion patterns during dynamic shoulder movements with the use of a direct technique. Direct measurement of active scapular motion was accomplished by insertion of 2 1.6-mm bone pins into the spine of the scapula in 8 healthy volunteers (5 men, 3 women). A small, 3-dimensional motion sensor was rigidly fixed to the scapular pins. Sensors were also attached to the thoracic spine (T3) with tape and to the humerus with a specially designed cuff. During active scapular plane elevation, the scapula upwardly rotated (mean [SD] = 50 degrees [4.8 degrees ]), tilted posteriorly around a medial-lateral axis (30 degrees [13.0 degrees ]), and externally rotated around a vertical axis (24 degrees [12.8 degrees ]). Lowering of the arm resulted in a reversal of these motions in a slightly different pattern. The mean ratio of glenohumeral to scapulothoracic motion was 1.7:1. Normal scapular motion consists of substantial rotations around 3 axes, not simply upward rotation. Understanding normal scapular motion may assist in the identification of abnormal motion associated with various shoulder disorders.

A review of self-report scales for the assessment of functional limitation and disability of the shoulder

A shoulder disorder affects a patient's overall quality of life. Self-report outcome measures can be used to assess the effects of shoulder dysfunction in terms of patients' functional limitations and disabilities. Selection of a shoulder-specific scale from the numerous scales available can be overwhelming. The purpose of this study was to review the self-report scales in current use for assessing the shoulder joint. A MEDLINE literature search was performed to locate scales appropriate to the assessment of function and disability of the shoulder. Only scales with established measurement properties were selected for review. Eleven scales were reviewed. Methodological and practical criteria were established to evaluate each scale. All scales met the minimal criteria, but not all scales were equal with regard to the criteria established for analysis.

Dynamic measurements of three-dimensional scapular kinematics: a validation study

The validation of two noninvasive methods for measuring the dynamic three-dimensional kinematics of the human scapula with a magnetic tracking device is presented. One method consists of simply fixing a sensor directly to the acromion and the other consists of mounting a sensor to an adjustable plastic jig that fits over the scapular spine and acromion. The concurrent validity of both methods was assessed separately by comparison with data collected simultaneously from an invasive approach in which pins were drilled directly into the scapula. The differences between bone and skin based measurements represents an estimation of skin motion artifact. The average motion pattern of each surface method was similar to that measured by the invasive technique, especially below 120 degrees of elevation. These results indicate that with careful consideration, both methods may offer reasonably accurate representations of scapular motion that may be used to study shoulder pathologies and help develop computational models.

Scapular kinematics: effects of altering the Euler angle sequence of rotations

An analysis of Euler angle sequences is presented for the scapula. In vivo kinematics were collected with a magnetic tracking device on eight healthy volunteers. To ensure accurate representation of scapular motion, pins were rigidly drilled into the scapular spine. Three rotations of the scapula with respect to the thorax were recorded during humeral elevation in the scapular plane: posterior (or backward) tilting, upward (or lateral) rotation and external rotation (or retraction). Rotations using all six possible Euler angle sequences were calculated for which each angle was represented only once. The sequence proposed by an International Society of Biomechanics subcommittee on shoulder motion (external rotation, upward rotation, posterior tilting) is consistent with both research- and clinical-based two-dimensional representations of scapular motion. Results from the present study indicate that changing sequence results in significant alterations in the description of motion, with differences up to 50 degrees noted for some angles. Therefore, in order to compare results across different laboratories, it is recommended that the proposed standard sequence be adopted.

Comparison of 3-dimensional scapular position and orientation between subjects with and without shoulder impingement

STUDY DESIGN

Nonrandomized 2 group post-test only.

OBJECTIVE

To compare scapular position and orientation between subjects with and without impingement syndrome.

BACKGROUND

Abnormal scapular motion is commonly believed to be a contributing factor to shoulder impingement syndrome.

METHODS AND MEASURES

Twenty nonimpaired subjects with a mean age of 34.3 (+/- 7.5 years) and 17 patients with impingement syndrome with a mean age of 45.8 (+/- 11.0) participated. A 3-dimensional electromechanical digitizer was used to measure scapular position and orientation in 3 planes. Measurements were taken with the arm at the side, elevated in the scapular plane to horizontal, and at maximum elevation. One-way analysis of variance was used to compare nonimpaired subjects to the impingement group and the symptomatic and asymptomatic sides within the impingement group. Five scapular kinematic variables were assessed at each arm position. Orientation was described by posterior tilting angle, upward rotation angle, and internal rotation angle. Position was described by medial-lateral position and superior-inferior position and determined by the distance from the scapula centroid to the seventh cervical vertebra (C7).

RESULTS

During scapular plane elevation of the arm, the scapula showed a general pattern of increasing posterior-tilt angle, increasing upward-rotation angle, and decreasing internal-rotation angle in both impingement and nonimpaired groups. Also, the scapula moved to a more superior position and a slightly more medial position with increasing arm elevation. Compared to nonimpaired subjects (34.6 degrees +/- 9.7), those with impingement demonstrated a significantly lower posterior tilting angle of the scapula in the sagittal plane (25.1 degrees +/- 9.1). Subjects with impingement also demonstrated higher superior-inferior scapular position with maximal arm elevation (5.2 cm +/- 1.6 below the first thoracic vertebrae) compared to nonimpaired subjects (7.5 cm +/- 1.5).

CONCLUSIONS

These results suggest that altered scapular kinematics may be an important aspect of the impingement syndrome.