Published online before print August 9, 2007, 10.1148/radiol.2443060998
(Radiology 2007;244:815-822.)
© RSNA, 2007
Abduction and External Rotation in Shoulder Impingement: An Open MR Study on Healthy Volunteers—Initial Experience1
Garry E. Gold, MD,
George P. Pappas, MD, PhD,
Silvia S. Blemker, PhD,
Sean T. Whalen, MS,
Gordon Campbell, MD,
Timothy A. McAdams, MD, and
Christopher F. Beaulieu, MD, PhD
1 From the Departments of Radiology (G.E.G., S.T.W., C.F.B.) and Orthopedic Surgery (G.C., T.M.), Stanford University School of Medicine, 300 Pasteur Dr, SO-68B, Stanford, CA 94305-5105; Harvard Combined Orthopaedics Program, Department of Orthopaedic Surgery, Massachusetts General Hospital, Boston, Mass (G.P.P.); and Department of Mechanical and Aerospace Engineering, University of Virginia, Charlottesville, Va (S.S.B.). Received June 9, 2006; revision requested August 15; revision received November 11; accepted December 7; final version accepted February 2, 2007. Supported by NIH grants EB002524-01 and EB005790-01 and by the Whitaker and Lucas Foundations.
Address correspondence to G.E.G. gold{at}stanford.edu).
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ABSTRACT
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Purpose: To prospectively evaluate rotator cuff contact with the glenoid in healthy volunteers placed in the unloaded and loaded abduction and external rotation (ABER) positions in an open magnetic resonance (MR) imager.
Materials and Methods: The study was institutional review board approved and HIPAA compliant, and informed consent was received. Eight male volunteers with no history of shoulder pain or pathology were imaged in a 0.5-T open MR imager. Volunteers were imaged in an unloaded ABER position with the arm at 90° abduction and in a loaded ABER position, with a 1-kg load that produced an average external rotation of 111° ± 6 (standard deviation). Two radiologists graded rotator cuff contact on a three-point scale. Three-dimensional anatomic models generated from the MR images were used to measure distances. Minimum distances were computed between the tendon insertion sites and the glenoid, acromion, and coracoid for the loaded ABER position. Minimum distances were compared by using a paired Student t test.
Results: In the unloaded ABER position, contact was seen between the infraspinatus and supraspinatus tendons and the glenoid in all eight volunteers. In the loaded ABER position, contact was also observed between the infraspinatus and supraspinatus and the posterior and posterosuperior glenoid, respectively. Deformation of the infraspinatus on the glenoid was seen in four volunteers, whereas supraspinatus deformation was only seen in one volunteer. The minimum distance between the supraspinatus insertion and acromion in the loaded ABER position decreased significantly (P < .01). Supraspinatus tendon to glenoid and infraspinatus tendon to glenoid minimum distances also decreased significantly (P < .01).
Conclusion: The unloaded and loaded ABER positions resulted in contact of the supraspinatus and infraspinatus with the glenoid in all volunteers. Distances between the rotator cuff insertion sites and the glenoid decreased in the loaded ABER position.
© RSNA, 2007
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INTRODUCTION
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Posterosuperior glenohumeral impingement is a clinical syndrome seen predominately in young athletes who perform overhead throwing (1–4). This syndrome is thought to arise from repeated impingement of the undersurface of the rotator cuff on the posterosuperior glenoid during the late cocking phase of throwing (2). These patients often complain of posterior shoulder pain (5,6). At conventional magnetic resonance (MR) imaging and MR arthrography, findings associated with this syndrome include labral and undersurface tears to the rotator cuff tendons, specifically the supraspinatus and infraspinatus tendons (7,8).
Tirman et al (9) established the usefulness of performing MR examinations of the shoulder in a closed-bore imager with the abduction and external rotation (ABER) position. This position is useful in the diagnosis of undersurface tears of the rotator cuff and abnormalities of the biceps labral complex (10,11). This position is also useful to evaluate signs that are seen during internal impingement (8).
Contact between the rotator cuff tendons and the labrum and glenoid is commonly seen in healthy volunteers placed in the nonloaded ABER position in a closed-bore imager. Giaroli et al (8) showed that contact between the rotator cuff and glenoid could be seen in control subjects. Halbrecht et al (12) showed that in both the throwing and nonthrowing shoulders of young baseball players there was contact between the rotator cuff undersurface and the subjacent labrum when placed in the ABER position. Schickendantz et al (13) also concluded that contact between the glenoid and undersurface of the rotator cuff can be seen in healthy volunteers. In an arthroscopic study, McFarland et al (3) concluded that the intraoperative finding of contact of the rotator cuff to the posterosuperior glenoid with the arm in the ABER position can occur in a wide spectrum of shoulder disease and is not limited to the throwing athlete.
Clinical examination of the shoulder for anterior instability is performed in the ABER position with the arm abducted at 90° and the shoulder in forced external rotation (14,15). However, placement of subjects in the ABER position in a conventional, closed-bore MR system is limited in terms of the ability to add load to the patient's arm (9). Open configuration MR systems have been used to assess glenohumeral stability during physiologic motion and under stress (16,17). Graichen et al (18) used an open MR system to study the subacromial space during abduction and rotation. Open MR imaging has also been used to characterize the Neer and Hawkins signs of subacromial impingement (19).
Thus, the purpose of our study was to prospectively evaluate rotator cuff contact with the glenoid in healthy volunteers when placed in the unloaded and loaded ABER positions in an open MR imager.
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MATERIALS AND METHODS
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Volunteers and Imaging
The study was institutional review board approved (Stanford University, Stanford, Calif) and HIPAA compliant, and informed consent was obtained. MR imaging was performed in eight healthy male volunteers (age range, 19–21 years) who had no history of shoulder pain. Prior to MR imaging, a physical examination of the right shoulder was performed on each volunteer by an orthopedic surgeon (G.C., with 27 years experience in physical examination of the shoulder). All volunteers exhibited normal surface anatomy, range of motion, strength, and stability; no tenderness at palpation was elicited. The apprehension sign, with the shoulder in the ABER position, was negative for all volunteers. Force applied to the back of the shoulder with the arm in the ABER position did not elicit pain in any volunteer. All volunteers were right-handed.
All images were acquired by using a 0.5-T MR imager (Signa SP; GE Healthcare, Milwaukee, Wis) with a transmit/receive surface coil. Images were acquired with the arm in neutral position in both the transverse and oblique coronal planes. Images were acquired in the transverse plane primarily to evaluate the insertion of the subscapularis tendon and in the oblique coronal plane to evaluate the insertions of the supraspinatus and infraspinatus tendons. Images with the arm in unloaded and loaded ABER positions were acquired in the transverse plane only.
To facilitate segmentation, we used a three-dimensional (3D) gradient-recalled-echo sequence with repetition time msec/echo time msec, 30/10; flip angle, 35°; field of view, 20 cm; matrix, 256 x 160; and section thickness, 2 mm. One signal was acquired; imaging bandwidth was ± 31.5 kHz, and imaging time for each series was 4 minutes 35 seconds. The image resolution was chosen to obtain a good signal-to-noise ratio with our coil within the scan time that our volunteers could remain motionless in the loaded ABER position.
Volunteers were imaged with the right arm in three different positions: (a) neutral, with the arm resting at the volunteer's side; (b) the unloaded ABER position; and (c) the loaded ABER position (Fig 1). First, 3D gradient-recalled-echo images of the right shoulder in the neutral position were acquired in both the coronal and transverse planes. Subsequently, transverse images of the shoulder were acquired with the arm in the unloaded and loaded ABER positions.
In the loaded ABER position, a 1-kg load was applied at the wrist (Fig 1b) to simulate the forced external rotation applied during a clinical examination without causing excessive discomfort during the approximately 5-minute scan (20,21). Volunteers were at rest and did not actively resist the external rotation moment imposed by the load. A goniometer was used to confirm arm 90° abduction and 90° external shoulder rotation in the unloaded ABER position. External rotation in the loaded ABER position averaged 111° ± 6 (range, 102°–118°).
Image Evaluation
Two radiologists (G.E.G. and C.F.B., with 10 and 15 years experience in shoulder MR, respectively) visually graded infraspinatus and supraspinatus tendon contact with the glenoid in the neutral, unloaded ABER, and loaded ABER positions. Contact was graded on a scale of 0-2: Score of 0, no contact between structures; score of 1, contact between structures without tendon deformation; score of 2, contact with deformation of the supraspinatus or infraspinatus. Disagreements over grading were resolved by consensus. The location of contact on the glenoid was determined by using the markings on a clock face as in Resch et al (22) study, where superior is 12 o'clock, inferior is 6 o'clock, anterior is 3 o'clock, and posterior is 9 o'clock for the right shoulder. Evaluation of the unloaded and loaded ABER positions was performed in a blinded manner by randomizing the loaded and unloaded series for all volunteers at the time of the evaluation.
Three-dimensional Model Creation
A single observer (G.P.P., with 5 years experience in image segmentation) performed segmentation of the bones of the shoulder and the rotator cuff insertions, supervised by a musculoskeletal radiologist (G.E.G., with 10 years experience in musculoskeletal MR). A 3D surface model of the glenoid, coracoid, and acromion and supraspinatus, infraspinatus, and subscapularis insertion sites was created from each series of contiguous two-dimensional MR images. In each two-dimensional image, the anatomic structures were outlined manually by defining a series of points that were connected by a cardinal spline. This is similar to the method used by Chang et al (23) to analyze acromial shape. The outlines for each structure were then combined to form a 3D polygonal surface mesh (Nuages, INRIA, France). The resulting surface models of the anatomic structures were imported to a graphics-based musculoskeletal modeling environment (SIMM [Software for Interactive Musculoskeletal Modeling]; Musculographics, Santa Rosa, Calif) (24).
In the loaded ABER position, surface models for the humerus, glenoid, and acromion were created from the single set of transverse images. In the neutral position, surface models for all structures were built from transverse and coronal image series and combined to form a complete representation (Fig 2). For example, the proximal aspect of the humeral head was taken from the coronal reconstruction and added to the transverse reconstruction to form a full reconstruction of the proximal humerus. The humerus and scapula from the detailed neutral-position models were registered to the humerus and scapula reconstructions in loaded ABER position (Fig 3).
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Figure 2a: Computer-generated models from MR image data of shoulder in neutral position. (a) Anterior and (b) posterior views of insertion sites of rotator cuff tendons. Red = supraspinatus, blue = infraspinatus, yellow = subscapularis.
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Figure 2b: Computer-generated models from MR image data of shoulder in neutral position. (a) Anterior and (b) posterior views of insertion sites of rotator cuff tendons. Red = supraspinatus, blue = infraspinatus, yellow = subscapularis.
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Figure 3a: Computer-generated models from MR image data of shoulder in loaded ABER position. (a) Anterior, (b) posterior (arrow = minimum distance between the glenoid and infraspinatus insertion), and (c) inferior views show insertion sites of rotator cuff tendons. Red = supraspinatus, blue = infraspinatus, yellow = subscapularis. Note proximity of labrum to infraspinatus insertion site.
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Figure 3b: Computer-generated models from MR image data of shoulder in loaded ABER position. (a) Anterior, (b) posterior (arrow = minimum distance between the glenoid and infraspinatus insertion), and (c) inferior views show insertion sites of rotator cuff tendons. Red = supraspinatus, blue = infraspinatus, yellow = subscapularis. Note proximity of labrum to infraspinatus insertion site.
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Figure 3c: Computer-generated models from MR image data of shoulder in loaded ABER position. (a) Anterior, (b) posterior (arrow = minimum distance between the glenoid and infraspinatus insertion), and (c) inferior views show insertion sites of rotator cuff tendons. Red = supraspinatus, blue = infraspinatus, yellow = subscapularis. Note proximity of labrum to infraspinatus insertion site.
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An iterative closest-point algorithm (25) and a nonlinear, least-squares algorithm (MATLAB Optimization Toolbox; The Mathworks, Natick, Mass) were used to register the surface reconstructions of the humerus and scapula in the neutral position to the humerus and scapula models in the loaded ABER position. The inputs to the algorithm were two polygonal surfaces that were originally apart from each other. The algorithm determined which transformation to apply to one of the surfaces to minimize the distance between the two surfaces. This algorithm has been widely used; for example, it has been used to calculate scapular kinematics (26) and to register lower limb bone surfaces built from orthogonal sets of MR images (27). We used the model to calculate the minimum distances rather than the source MR data. This allowed us to use both the transverse and coronal MR images to determine the minimum distance, giving an objective measure and minimizing error due to partial volume artifact.
Performing this registration step allowed the use of the detailed reconstructions generated from the neutral position images, which included optimal coverage of the muscle insertions, to calculate minimum distances in the loaded ABER position. The loaded ABER position was chosen for the model analysis because it most closely simulated the apprehension test position and the late cocking phase of throwing. As stated by Jobe et al (2), "[d]uring the late cocking phase, the humerus is moving toward maximal external rotation." Hence, minimum distances were not calculated for the unloaded ABER position.
Minimum Distance Measurements
Three-dimensional anatomic models generated from the MR images were used to measure distances in the neutral and loaded ABER positions. Minimum distances between the humerus and the scapula were calculated by using a computer (Silicon Graphics Workstation; SGi, Mt. View, Calif) running MATLAB (Mathworks, Natick, Mass). Specifically, minimum distances were computed between (a) the greater and lesser tuberosities and the supraspinatus, infraspinatus, and subscapularis insertion sites of the humerus and (b) the glenoid and acromion. For each polygon in each humeral surface, the closest point on the scapular surface was found; the minimum distance between the two surfaces was the closest polygon-point distance.
Statistical Analysis
Statistical analysis was performed by using Excel (version 11.1.1; Microsoft, Redmond, Wash) and Stata (version 9.2; Stata, College Station, Tex) software. A 
analysis was performed to measure interobserver agreement for image evaluation. The differences between the minimum distances for the neutral position and the loaded ABER position were compared by using a two-tailed, paired Student t test. A P value of less than .01 was considered to indicate a significant difference, indicating that the mean change in the distance between structures was greater than that expected from random variation. Descriptive statistics are reported as mean value ± standard deviation. Confidence intervals for the differences in minimum distances were also computed.
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RESULTS
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Image Evaluation
In the unloaded ABER position, contact (grade 1) was observed between the supraspinatus and the posterosuperior glenoid (11 o'clock) in all eight volunteers. Similarly, in the unloaded ABER position, contact was seen between the infraspinatus and posterior glenoid (9 o'clock) in all eight volunteers. Deformation (grade 2) of the rotator cuff tendons was not seen in any of the volunteers in the unloaded ABER position.
In the loaded ABER position, all eight volunteers showed contact (grade 1) between the supraspinatus near the insertion and posterosuperior glenoid (Table 1). Similarly, in the loaded ABER position, contact was seen between the infraspinatus near the insertion and posterior glenoid in all eight volunteers. Deformation of the infraspinatus tendon (grade 2) on the posterior glenoid was seen in four of eight volunteers in the loaded ABER position (Fig 4). Supraspinatus tendon deformation on the posterosuperior glenoid was seen in only one volunteer placed in the loaded ABER position. Intraobserver agreement between the two radiologists on supraspinatus and infraspinatus tendon contact with the glenoid was excellent ( = 0.875).
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Figure 4a: Transverse 3D gradient-echo MR images (30/10) with volunteer in (a) neutral position, (b) unloaded ABER position at 90° external rotation, and (c) 111° external rotation. Note infraspinatus tendon (arrow) deformed between the greater tuberosity and posterosuperior glenoid in the loaded study.
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Figure 4b: Transverse 3D gradient-echo MR images (30/10) with volunteer in (a) neutral position, (b) unloaded ABER position at 90° external rotation, and (c) 111° external rotation. Note infraspinatus tendon (arrow) deformed between the greater tuberosity and posterosuperior glenoid in the loaded study.
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Figure 4c: Transverse 3D gradient-echo MR images (30/10) with volunteer in (a) neutral position, (b) unloaded ABER position at 90° external rotation, and (c) 111° external rotation. Note infraspinatus tendon (arrow) deformed between the greater tuberosity and posterosuperior glenoid in the loaded study.
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The infraspinatus tendon did not contact the acromion in either the loaded or unloaded ABER position in any of our volunteers. Contact between the supraspinatus and acromion was seen in only one volunteer. The supraspinatus tendon showed deformation on the acromion in the loaded ABER position in the same volunteer.
Minimum Distances
The minimum distance between the supraspinatus insertion and acromion (16.9 mm ± 4.8, neutral position) decreased significantly (P < .01) in the loaded ABER position to 5.7 mm ± 3.0 (Fig 5). The distances between the acromion and the greater tuberosity, lesser tuberosity, and subscapularis insertion also decreased significantly (P < .01), although they did not come as close as the supraspinatus insertion. The P values and 95% confidence intervals for the differences in minimum distance between neutral and loaded ABER positions confirm these differences (Table 2).
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Figure 5: Graph shows average minimum distance (± standard deviation) for eight volunteers from the acromion to the humeral head in neutral and loaded ABER position. * = structure was significantly closer (P < .01) to acromion in loaded ABER position. GT = greater tuberosity, Infra = infraspinatus insertion site, LT = lesser tuberosity, Subscap = subscapularis insertion site, Supra = supraspinatus insertion site.
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The infraspinatus to glenoid distance (38.4 mm ± 2.4, neutral position) decreased significantly (P < .01) in the loaded ABER position to 3.6 mm ± 1.7 (Fig 6). Supraspinatus to glenoid distance (35.0 mm ± 2.8, neutral position) decreased significantly (P < .01) in the loaded ABER position to 6.6 mm ± 3.6. The distance between the greater tuberosity and the glenoid (21.5 mm ± 1.7, neutral position) decreased significantly in the loaded ABER position (P < .01) to 3.6 mm ± 1.5, suggesting a large portion of the greater tuberosity (including the supraspinatus and infraspinatus insertions) may be important in the minimum distance measurement. The lesser tuberosity was significantly farther from the glenoid in the loaded ABER position (P < .01). The P values and 95% confidence intervals for the differences in minimum distance between neutral and loaded ABER position confirm these differences (Table 2).
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Figure 6: Graph shows average minimum distance (± standard deviation) for eight volunteers from the glenoid to humeral head in loaded ABER position. * = structure was significantly closer (P < .01) to glenoid in loaded ABER position (P < .01). Abbreviations same as in Figure 5.
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DISCUSSION
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Posterosuperior glenohumeral impingement is associated with pain, undersurface tears to the rotator cuff, and abnormalities in the posterosuperior glenoid labrum in throwing athletes (1,2,28,29). Our study indicates that healthy volunteers placed in a position of loaded ABER show anatomic changes consistent with the pathologic history seen in this syndrome.
Significant decreases in the minimum distance between the greater tuberosity (specifically, the supraspinatus and infraspinatus insertions) and the glenoid were observed in the loaded ABER position. The infraspinatus insertion, in particular, came to within 3.6 mm from the glenoid, on average, in this position. Decrease in minimum distance, however, does not translate directly into clinical impingement. In one study (30) of subcoracoid impingement, the asymptomatic patients had an even narrower subcoracoid distance than the clinical symptomatic patients.
We observed contact between the infraspinatus tendon and posterior glenoid, as well as between the supraspinatus tendon and the posterosuperior glenoid. This finding was also recorded in baseball players placed in the ABER position in a closed-bore MR system (12). Deformation of the infraspinatus tendon by the glenoid was observed in one-half of the volunteers when placed in the loaded ABER position. This may have been due to the applied force of the weight increasing the degree of external rotation of the arm. This finding suggests contact between the rotator cuff and glenoid may occur in asymptomatic individuals during loaded ABER position of the shoulder. This is consistent with results seen previously with closed-bore MR images and unloaded ABER, as well as at arthroscopy (3,8,12).
Subacromial shoulder impingement is associated with pain and rotator cuff abnormalities caused by contact of the bursal surface of the cuff with the coracoacromial arch. Our study demonstrated that healthy volunteers placed in the loaded ABER position showed decreases in the minimum distances between the greater tuberosity, lesser tuberosity, supraspinatus tendon insertion, and subscapularis insertion and the acromion. Only the infraspinatus tendon insertion did not show a significant decrease in minimum distance to the acromion. This suggests that the loaded ABER position may be more specific for internal, rather than subacromial, impingement.
Our study had several limitations. Only one observer segmented the rotator cuff insertions on the humeral head, although a more experienced observer verified this. We used two experienced observers to grade contact in the ABER position, with disagreements resolved by consensus, so testing of intra- or interobserver variability was not possible. Complete blinding of the observers to loaded versus unloaded images was not possible due to the change in position of the humerus as seen on the images.
We used a small number of healthy volunteers, rather than subjects with shoulder pain. Our volunteers' muscles were imaged at rest, rather than while actively contracting, making extrapolation to active states difficult. Instability, internal rotation deficit, and scapular muscle dysfunction were not assessed in our volunteers beyond the physical examination, and these findings are associated with internal impingement (31).
We used 3D gradient-echo MR imaging sequences to evaluate each shoulder, so subclinical pathologic evidence may not have been detected as it would have been at clinical MR. The resolution of our MR images was limited by field strength and imaging time constraints that affect the accuracy of the modeling and subjective imaging results. Exact 3D mapping of the tendon insertion sites was limited by image resolution, signal-to-noise ratio, and the merging of the supraspinatus and infraspinatus insertions. Further research is required to compare these findings with those in symptomatic throwing athletes.
Our results indicate that even in asymptomatic volunteers, contact and deformation of tendons may occur in the loaded ABER position. Observation of contact and deformation in symptomatic individuals may not illustrate the mechanical derangement associated with pain or tendon abnormality. The current results, combined with those obtained in a similar study of the Neer and Hawkins position (19) should enable clinicians to better understand which structures are in contact during physical examination. Individual variation and variation over time may occur, requiring study of a larger population.
In conclusion, we quantified the degree of contact of the rotator cuff with the glenoid in the loaded ABER position in healthy volunteers by using open MR imaging.
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ADVANCES IN KNOWLEDGE
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- Open MR imaging can be used to create three-dimensional models of shoulder and rotator cuff anatomy in loaded abduction and external rotation (ABER) positions.
- These models can be used to assess the minimum distances between structures such as the rotator cuff tendon insertions and the glenoid under load.
- Contact and deformation of the infraspinatus tendon on the glenoid occurs in healthy volunteers when placed in the loaded ABER position.
- Compared with the neutral position, the supraspinatus and infraspinatus tendon insertions were significantly closer to the glenoid in the loaded ABER position.
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IMPLICATIONS FOR PATIENT CARE
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- Contact between the glenoid and rotator cuff tendons may occur in healthy volunteers placed in the unloaded abduction and extended rotation (ABER) position in a closed-bore MR imager and cannot solely be used as a specific sign of pathologic evidence.
- Contact with the glenoid and deformation of the rotator cuff tendons may occur in healthy volunteers placed in the loaded ABER position on an open MR imager and cannot solely be used as a specific sign of pathologic evidence.
- These images may help the physician visualize the mechanics of internal shoulder impingement.
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FOOTNOTES
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Abbreviations: ABER = abduction and external rotation • 3D = three-dimensional
Author contributions: Guarantors of integrity of entire study, G.E.G., C.F.B.; study concepts/study design or data acquisition or data analysis/interpretation, all authors; manuscript drafting or manuscript revision for important intellectual content, all authors; approval of final version of submitted manuscript, all authors; literature research, G.E.G., G.P.P., C.F.B.; clinical studies, G.E.G., G.P.P., C.F.B.; statistical analysis, all authors; and manuscript editing, all authors
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References
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|---|
- Hackney RG. Advances in the understanding of throwing injuries of the shoulder. Br J Sports Med 1996;30:282–288.[Medline]
- Jobe CM. Superior glenoid impingement: current concepts. Clin Orthop Relat Res 1996;330:98–107.[CrossRef][Medline]
- McFarland EG, Hsu CY, Neira C, O'Neil O. Internal impingement of the shoulder: a clinical and arthroscopic analysis. J Shoulder Elbow Surg 1999;8:458–460.[CrossRef][Medline]
- Meister K. Internal impingement in the shoulder of the overhand athlete: pathophysiology, diagnosis, and treatment. Am J Orthop 2000;29:433–438.[Medline]
- Walch G, Boileau P, Noel E, Donell ST. Impingement of the deep surface of the supraspinatus tendon on the posterosuperior glenoid rim: an arthoscopic study. J Shoulder Elbow Surg 1992;1:238–245.
- Cavallo RJ, Speer KP. Shoulder instability and impingement in throwing athletes. Med Sci Sports Exerc 1998;30(suppl 4):S18–S25.
- Kaplan LD, McMahon PJ, Towers J, Irrgang JJ, Rodosky MW. Internal impingement: findings on magnetic resonance imaging and arthroscopic evaluation. Arthroscopy 2004;20:701–704.[Medline]
- Giaroli EL, Major NM, Higgins LD. MRI of internal impingement of the shoulder. AJR Am J Roentgenol 2005;185:925–929.[Abstract/Free Full Text]
- Tirman PF, Bost FW, Garvin GJ, et al. Posterosuperior glenoid impingement of the shoulder: findings at MR imaging and MR arthrography with arthroscopic correlation. Radiology 1994;193:431–436.[Abstract/Free Full Text]
- Cvitanic O, Tirman PF, Feller JF, Bost FW, Minter J, Carroll KW. Using abduction and external rotation of the shoulder to increase the sensitivity of MR arthrography in revealing tears of the anterior glenoid labrum. AJR Am J Roentgenol 1997;169:837–844.[Abstract/Free Full Text]
- Tirman PF, Bost FW, Steinbach LS, et al. MR arthrographic depiction of tears of the rotator cuff: benefit of abduction and external rotation of the arm. Radiology 1994;192:851–856.[Abstract/Free Full Text]
- Halbrecht JL, Tirman P, Atkin D. Internal impingement of the shoulder: comparison of findings between the throwing and nonthrowing shoulders of college baseball players. Arthroscopy 1999;15:253–258.[Medline]
- Schickendantz MS, Ho CP, Keppler L, Shaw BD. MR imaging of the thrower's shoulder: internal impingement, latissimus dorsi/subscapularis strains, and related injuries. Magn Reson Imaging Clin N Am 1999;7:39–49.[Medline]
- Valadie AL 3rd, Jobe CM, Pink MM, Ekman EF, Jobe FW. Anatomy of provocative tests for impingement syndrome of the shoulder. J Shoulder Elbow Surg 2000;9:36–46.[CrossRef][Medline]
- Clarnette RG, Miniaci A. Clinical exam of the shoulder. Med Sci Sports Exerc 1998;30(suppl 4):S1–S6.
- Beaulieu CF, Hodge DK, Bergman AG, et al. Glenohumeral relationships during physiologic shoulder motion and stress testing: initial experience with open MR imaging and active imaging-plane registration. Radiology 1999;212:699–705.[Abstract/Free Full Text]
- Hodge DK, Beaulieu CF, Thabit GH 3rd, et al. Dynamic MR imaging and stress testing in glenohumeral instability: comparison with normal shoulders and clinical/surgical findings. J Magn Reson Imaging 2001;13:748–756.[CrossRef][Medline]
- Graichen H, Bonel H, Stammberger T, Englmeier KH, Reiser M, Eckstein F. Subacromial space width changes during abduction and rotation: a 3-D MR imaging study. Surg Radiol Anat 1999;21:59–64.[Medline]
- Pappas GP, Blemker SS, Beaulieu CF, McAdams TR, Whalen ST, Gold GE. In vivo anatomy of the Neer and Hawkins sign positions for shoulder impingement. J Shoulder Elbow Surg 2006;15:40–49.[CrossRef][Medline]
- Graichen H, Stammberger T, Bonel H, et al. Three-dimensional analysis of shoulder girdle and supraspinatus motion patterns in patients with impingement syndrome. J Orthop Res 2001;19:1192–1198.[CrossRef][Medline]
- Sigholm G, Herberts P, Almstrom C, Kadefors R. Electromyographic analysis of shoulder muscle load. J Orthop Res 1984;1:379–386.[CrossRef][Medline]
- Resch H, Wykypiel HF, Maurer H, Wambacher M. The antero-inferior (transmuscular) approach for arthroscopic repair of the Bankart lesion: an anatomic and clinical study. Arthroscopy 1996;12:309–319.[Medline]
- Chang EY, Moses DA, Babb JS, Schweitzer ME. Shoulder impingement: objective 3D shape analysis of acromial morphologic features. Radiology 2006;239:497–505.[Abstract/Free Full Text]
- Delp SL, Loan JP. A graphics-based software system to develop and analyze models of musculoskeletal structures. Comput Biol Med 1995;25:21–34.[CrossRef][Medline]
- Besl PJ, McKay ND. A method for registration of 3-D shapes. IEEE Trans Pattern Anal Mach Intell 1992;14:239–256.[CrossRef]
- Fung M, Kato S, Barrance PJ, et al. Scapular and clavicular kinematics during humeral elevation: a study with cadavers. J Shoulder Elbow Surg 2001;10:278–285.[CrossRef][Medline]
- Arnold AS, Salinas S, Asakawa DJ, Delp SL. Accuracy of muscle moment arms estimated from MRI-based musculoskeletal models of the lower extremity. Comput Aided Surg 2000;5:108–119.[CrossRef][Medline]
- Edelson G, Teitz C. Internal impingement in the shoulder. J Shoulder Elbow Surg 2000;9:308–315.[CrossRef][Medline]
- Hawkins RJ, Kennedy JC. Impingement syndrome in athletes. Am J Sports Med 1980;8:151–158.[Abstract/Free Full Text]
- Giaroli EL, Major NM, Lemley DE, Lee J. Coracohumeral interval imaging in subcoracoid impingement syndrome on MRI. AJR Am J Roentgenol 2006;186:242–246.[Abstract/Free Full Text]
- Conway JE. Arthroscopic repair of partial-thickness rotator cuff tears and SLAP lesions in professional baseball players. Orthop Clin North Am 2001;32:443–456.[CrossRef][Medline]
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A. M. Saleem, J. K. Lee, and L. M. Novak
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Am. J. Roentgenol.,
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[PDF]
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ABSTRACT
INTRODUCTION
