Abduction And External Rotation Research Articles

Trans-axillary sonography in the ABER (ABduction and External Rotation) position: a window to the subscapularis, teres major and latissimus dorsi.

Shoulder ultrasound is a key tool used by musculoskeletal practitioners to diagnose and treat a variety of upper girdle diseases. While magnetic resonance imaging is the cornerstone of shoulder imaging, sonography is readily available, practical and superior in its ability for dynamic assessment of musculoskeletal pathologies. The subscapularis, teres major and latissimus dorsi muscles are commonly involved in a myriad of pathology including myofascial pain and spasticity. There is scarce literature on the assessment of these muscles for diagnostic and therapeutic purposes. Conventional approaches to shoulder ultrasound have not included a dedicated assessment of the subscapularis muscle due to its inherent anatomical location deep to the scapular blade which blocks sound wave penetration. We describe an approach to visualizing the subscapularis muscle as a short addition to the established shoulder sonography format, which also permits assessment of both the latissimus dorsi and teres major muscles, which are important muscles for shoulder spasticity. The patient is imaged in a semi-recumbent position with the arms elevated above and behind the head in the ABduction and External Rotation (ABER) position. The relative ease of positioning and sonographic access to the musculature coupled with the potential for assessment and intervention makes this approach extremely desirable to the musculoskeletal practitioner looking to diagnose or treat muscle belly pathologies of the subscapularis, teres major or latissimus dorsi.

Diagnostic performance of MRA in abduction and external rotation position in the detection of glenoid labral lesions: a systematic review and meta-analysis.

To compare the diagnostic performance of direct magnetic resonance arthrography (MRA) for labral lesions during conventional, abduction and external rotation (ABER), conventional plus abduction, and external rotation (ABER) positioning by using a systematic review and meta-analysis. A comprehensive literature search was performed on the two main concepts of magnetic resonance arthrography: extremity position and labral lesions. Inclusion criteria consisted of original studies that assessed the diagnostic accuracy of MR arthrography in ABER and conventional position alone or combined for the diagnosis of labral lesions by using surgical findings as the reference standard. Meta-analyses were performed that compared MR arthrography during conventional positioning, ABER, and conventional plus ABER positioning. Nine studies met the inclusion and exclusion criteria. A total of 733, 504, and 313 lesions assessed by conventional MRA, ABER MRA, and conventional plus ABER MRA, respectively, were included in our analysis. Pooled sensitivities of MRA in conventional, ABER, and conventional plus ABER position for labral tear diagnosis were 81.5%, 81.6%, and 95.7%, respectively. Pooled specificities of MRA in conventional, ABER, and conventional plus ABER position for labral tear diagnosis were 88.8%, 85.6%, and 94.5%, respectively. Summary receiver operator characteristic (ROC) curve demonstrated improved accuracy of conventional plus ABER MRA compared with conventional MRA or ABER MRA with the area under the curve (AUC) of 0.99, 0.90, and 0.88, respectively. Conventional plus ABER MRA showed increased diagnostic accuracy compared to both ABER MRA and conventional MRA alone in the diagnosis of labral lesions.

Role of ABER Positioning in Evaluation of Anteroinferior Labroligamentous Lesions in Shoulder MR Arthrograms

Background: MR arthrography in the abduction and external rotation (ABER) position has been demonstrated to enhance the diagnostic ratio of anterior labro-ligamentous complex tears. Meanwhile, the diagnostic and discriminatory rates of MR arthrography in this position in various types of the antero-inferior labro-ligamentous lesions have not been completely discovered. Aim: This study aimed to perform comparison between ABER MR and the conventional MR arthrography considering the diagnostic rate and discriminatory precision of various anteroinferior labro-ligamentous lesions. Methods: We studied 38 patients who suffered from shoulder conditions and evaluated the results of both conventional MR and ABER MR arthrography. An antero-inferior labro-ligamentous lesion was diagnosed with the detection of absence, fray, detachment, displacement of the antero-inferior labrum or detection of the contrast material inside the labrum, or avulsion, rupture of the inferior glenohumeral ligament at the humeral or labral attachment. All study subjects have undergone shoulder arthroscopy after MR technique. Results: ABER MR arthrography was associated with significant increased accuracy and diagnostic sensitivity than that of conventional MR regarding the diagnostic rate of various types of the antero-inferior labro-ligamentous lesions (p < 0.05). Conclusion: Based on our results, ABER MR arthrography would add more value to the diagnosis if the conventional MR were doubtful in suspected antero-inferior labro-ligamentous complex injuries.

Diagnosis of Engaging Bipolar Bone Defects in the Shoulder Using 2-Dimensional Computed Tomography

Background: Anatomic studies have demonstrated that bipolar glenoid and humeral bone loss have a cumulative effect on shoulder instability and that these defects may engage in functional positions depending on their size and location, potentially resulting in failure of stabilization procedures. Determining which lesions pose a risk for engagement remains challenging, with arthroscopic assessments and a 3-dimensional computed tomography (CT)–based glenoid track method being accepted approaches at this time. Purpose: The purpose was to investigate the interaction of humeral and glenoid bone defects on shoulder engagement in a cadaveric model. Two alternative approaches to predicting engagement were evaluated: (1) CT of the shoulder in abduction and external rotation (ABER) and (2) measurement of the glenoid lesion width and measurement of a novel parameter, the intact anterior articular angle (IAAA), on conventional 2-dimensional multiplane reformats. Study Design: Controlled laboratory study. Methods: Hill-Sachs and glenoid defects of varying sizes were created in 12 cadaveric upper limbs, producing 45 bipolar defect combinations. The defect characteristics were assessed using CT with the shoulder in a neutral position. ABER CT was performed with the shoulder positioned in 60° of glenohumeral abduction (corresponding to 90° of abduction relative to the trunk) and 90° of external rotation. The IAAA was measured as the cartilage arc angle anterior to the Hill-Sachs defect on the axial slice bisecting the humeral head. The performance of the ABER CT and IAAA approaches to predicting engagement were compared with the glenoid track method. Results: Of the 45 defect combinations, 24 (53%) were classified as engaging using the glenoid track method. ABER CT predicted engagement accurately in 43 of 45 (96%), with a sensitivity and specificity of 92% and 100%, respectively. A logistic model based on the glenoid defect width and IAAA provided a prediction accuracy of 87%, with a sensitivity and specificity of 92% and 81%, respectively. Conclusion/Clinical Relevance: Bipolar lesions at risk for engagement can be identified accurately using an ABER CT scan or by performing 2-dimensional measurements of the glenoid defect width and IAAA on conventional CT multiplane reformats. This information will be useful for surgical planning in the setting of bipolar bone defects before shoulder stabilization.

Biomechanical Comparison of Acute Hill-Sachs Reduction and Remplissage to Treat Complex Anterior Instability

Objectives:Acute Hill-Sachs (HS) reduction represents a potential alternative method to remplissage for the treatment of an engaging HS lesion. The purpose of this study is to biomechanically compare the stabilizing effects of an acute HS reduction technique and remplissage in a complex instability model.Methods:This was a comparative cadaveric study of 6 shoulders. For the acute HS lesion, a unique model was used to create a 30% defect, compressing the subchondral bone while preserving the articular surface in a more anatomic fashion. In addition, a 15% glenoid defect was made in all specimens. The HS lesion was reduced through a lateral cortical window with a bone tamp, and the subchondral void was filled with Quickset (Arthrex) bone cement to prevent plastic deformation. Five scenarios were tested; intact specimen, bipolar lesion, Bankart repair, remplissage with Bankart repair and HS reduction technique with Bankart repair. Translation, kinematics and dislocation events were recorded.Results:For all 6 specimens no dislocations occurred after either remplissage or the reduction technique. At 90 degrees of abduction and external rotation (ABER), anterior-inferior translation was 11.1 mm (SD 0.9) for the bipolar lesion. This was significantly reduced following both remplissage (5.1±0.7 mm; p<0.001) and HS reduction (4.4 ±0.3 mm; p<0.001). For anterior-inferior translation there was no significant difference in translation between the reduction technique and remplissage (p=0.91). At 90 degrees of ABER, the intact specimens average joint stiffness was 7.0 ±1.0N/mm, which was not significantly different from the remplissage (7.8±0.9 N/mm; p=0.9) and reduction technique (9.1±0.6 N/mm; p=0.50). Compared with an isolated Bankart repair, the average external rotation loss after also performing a remplissage procedure was 4.3 ±3.5 deg (p=0.65), while average ER loss following HS reduction was 1.1 ±3.3 deg (p=0.99). There was no significant difference in external rotation between remplissage and the reduction technique (p=0.83).Conclusion:Similar joint stability was conferred following both procedures, though remplissage had 3.2-degree loss of ER in comparison. While not statistically significant, even slight ER loss may be clinically detrimental in overhead athletes. Overall, the acute reduction technique is a more anatomic alternative to the remplissage procedure with similar ability to prevent dislocation in a biomechanical model, making it a viable treatment option for engaging Hill-Sachs lesions.

RETRACTED: Abduction external rotation position in magnetic resonance arthrography for the diagnosis of rotator cuff tears.

This article aims at evaluating the effectiveness of abduction and external rotation (ABER) position used in magnetic resonance (MR) arthrography for diagnosing rotator cuff tears. A retrospective analysis was performed using 183 MR arthrography images of shoulder joint. Each patient was either examined in a neutral position or ABER position. Then the imaging results were compared with those diagnostic results obtained from shoulder arthroscopy. Also the specificity, sensitivity, negative predictive value, positive predictive value, and accuracy of MR arthrography in the two positions described above were evaluated. A total of 64 patients were diagnosed with rotator cuff tears using arthroscopy and the diagnostic results include 16 complete rotator cuff tears and 48 partial tears; 47 supraspinatus tendon tears and 17 posterosuperior cuff tears; 22 delamination tears and 26 tears complicated with anteroinferior labrum-ligament complex injuries. The differences in specificity, sensitivity, negative predictive value, positive predictive value and accuracy between neutral position and ABER position using MR arthrography were not statistically significant (all P>0.05). For diagnosing posterosuperior cuff tears, the sensitivity of ABER position was significantly higher than that of the neutral position (94.12% vs. 64.71%, P=0.034). For diagnosing delamination tears, the sensitivity and negative predictive value of ABER position were significantly higher than those of the neutral position (P=0.009 and P=0.036 respectively). For diagnosing rotator cuff tears complicated with anteroinferior labrum-ligament complex injuries, the sensitivity of ABER position was statistically higher than that of the neutral position (96.15% vs. 73.08%, P=0.021). This study suggests that MR arthrography in ABER position is a superior tool for diagnosing certain types of rotator cuff tears. Apart from that, MR arthrography in ABER position improved the detection rate of posterosuperior cuff tears, delamination tears and rotator cuff tears complicated with anteroinferior labrum-ligament complex injuries.

Foot Progression Angle Walking Test- An Effective Dynamic Test for the Diagnosis of Femoroacetabular Impingement and Hip Instability

Objectives:Clinical diagnosis of femoroacetabular impingement (FAI) and hip instability is determined by accurate history, physical examination, and imaging assessment. Currently, there is no ideal physical examination maneuver and certainly no dynamic method of testing. In this prospective study, we evaluate the Foot Progression Angle Walking (FPAW) test as a novel diagnostic tool that is sensitive and specific for the detection of FAI and hip instability.Methods:A prospective cohort of patients who presented with hip pain underwent FPAW testing in addition to the gold standard assessments for impingement and instability, the Flexion Adduction and Internal Rotation (FADIR) test and the Abduction and External Rotation (ABER) test, respectively. Baseline foot progression angles were initially recorded. Patients were then instructed to walk with foot progression angles: 1) internally rotated (-15º) and 2) externally rotated (+15º). A positive FPAW test was defined by an increase in hip pain with either internal or external rotation. Radiographs and/or magnetic resonance imaging were then used to evaluate for abnormal hip morphology and confirm diagnosis.Results:80 patients (53 Female) with hip pain were evaluated by FPAW testing. Imaging used to assess for hip pathology exhibited FAI (n=48), instability (n=26) and normal anatomic morphology (n=13). Baseline measurements showed a neutral foot progression (64%), out-toeing gait (35%), and in-toeing gait (1%). Analysis of FPAW testing showed a sensitivity of 75% and specificity of 66% for FAI; sensitivity 54% and specificity 61% for instability. A positive predictive value (FAI: 77%; Instability 40%) and negative predictive value (FAI 64%; Instability 73%) were also determined. In comparison, the FADIR test showed a sensitivity and specificity of 96% and 13% for FAI, respectively. Its positive predictive value was 62% while its negative predictive value was 67%. Abduction and external rotation testing showed a sensitivity and specificity of 42% and 96%, respectively for diagnosing instability. Its positive predictive value was 85% and negative predictive value was 78%.Conclusion:FPAW testing was found to be more sensitive and specific for detecting FAI than instability. The higher specificity and positive predictive value of FPAW in comparison to the FADIR test makes it a reliable tool to identify patients with impingement. The FPAW test appears to be an effective tool to reproduce hip pathology in FAI patients during weight-bearing activity and could be a useful adjunct to give further clinical prospective in FAI and hip instability.

Demystifying ABER (ABduction and External Rotation) sequence in shoulder MR arthrography.

ABduction and External Rotation (ABER) sequence in magnetic resonance (MR) arthrography of the shoulder is particularly important to better depict abnormal conditions of some glenohumeral joint structures and surrounding tissues by making imaging possible under a stress position relevant to pathologic conditions. Among the structures and tissues better depicted in this position are articular surface of the supraspinatus tendon, anteroinferior portion of the glenoid labrum, and anterior band of the inferior glenohumeral band. Despite these benefits of the ABER sequence, it is either not being used extensively as part of shoulder MR arthrograms or, when utilized, not properly assessed, mostly due to some practical difficulties in setting up the sequence and unfamiliarity with the alignment of structures displayed on MR images. In this technical note, we aimed to explain the ABER sequence planning in a step-by-step manner with emphasis on scout series set-up, and also present an outline of anatomic landmarks seen on ABER images.

Does the experience level of the radiologist, assessment in consensus, or the addition of the abduction and external rotation view improve the diagnostic reproducibility and accuracy of MRA of the shoulder?

To prospectively evaluate the influence of observer experience, consensus assessment, and abduction and external rotation (ABER) view on the diagnostic performance of magnetic resonance arthrography (MRA) in patients with traumatic anterior-shoulder instability (TASI). Fifty-eight MRA examinations (of which 51 had additional ABER views) were assessed by six radiologists (R1-R6) and three teams (T1-T3) with different experience levels, using a seven-lesion standardized scoring form. Forty-five out of 58 MRA examination findings were surgically confirmed. Kappa coefficients, sensitivity, specificity, and differences in percent agreement or correct diagnosis (p-value, McNemar's test) were calculated per lesion and overall per seven lesion types to assess diagnostic reproducibility and accuracy. Overall kappa ranged from poor (k = 0.17) to moderate (k = 0.53), sensitivity from 30.6-63.5%, and specificity from 73.6-89.9%. Overall, the most experienced radiologists (R1-R2) and teams (T2-T3) agreed significantly more than the lesser experienced radiologists (R3-R4: p = 0.014, R5-R6; p = 0.018) and teams (T2-T3: p = 0.007). The most experienced radiologist (R1, R2, R3) and teams (T1, T2) were also consistently more accurate than the lesser experienced radiologists (R4, R5, R6) and team (T3). Significant differences were found between R1-R4 (p = 0.012), R3-R4 (p = 0.03), and T2-T3 (p = 0.014). The overall performance of consensus assessment was systematically higher than individual assessment. Significant differences were established between T1-T2 and radiologists R3-R4 (p<0.001, p = 0.001) and between T2 and R3 (p<0.001/p = 0.001) or R4 (p = 0.050). No overall significant differences were found between the radiologists' assessments with and without ABER. The addition of ABER does not significantly improve overall diagnostic performance. The radiologist's experience level and consensus assessment do contribute to higher reproducibility and accuracy.

Functional outcome and the structural integrity of arthroscopic Bankart repair: a prospective trial.

Recurrent anterior shoulder dislocations are common in young patients with Bankart lesions. Arthroscopic repair is an established treatment; however, recurrent instability occurs in up to 35% of patients. It is unclear whether recurrence is the result of a failure of the surgical repair to heal or a repeat injury. The aim of the present pilot study was to assess radiographic healing of Bankart lesions 6 months post surgical repair and identify any correlations between radiographic findings and subsequent recurrent dislocations. Eighteen patients underwent arthroscopic Bankart repair for recurrent instability. Magnetic resonance (MR) arthrograms were obtained both pre-operatively and 6 months postoperatively. Standard T1 and T2 views were obtained along with an abduction and external rotation (ABER) view. Patients were followed for a minimum of 4 years for the risk of recurrence, and functional outcomes were obtained, including the American Shoulder and Elbow Surgeons Subjective Shoulder Scale, Ontario Shoulder Instability Index, Oxford Shoulder Instability Score and 12-Item Short Form Health Survey. Scores were correlated with pre-operative and postoperative MR findings. Six of 18 patients developed recurrent instability. We could not identify correlations between reconstructed labrum (labral bumper) position, failure at suture sites and ABER findings with recurrent instability or functional outcome. Paradoxically, there was a nonstatistically significant trend for patients with no clefts between the labrum and the glenoid at any points along the repair to have worse outcomes than patients with partial or complete clefts. In our pilot study, MR arthrogram was used to evaluate the labrum in detail 6 months postoperatively. Despite its proven ability to detect labral lesions, we were unable to demonstrate any features on postoperative MR arthrogram that predicted either functional outcome or recurrent instability. At 6 months post operation, functional recovery and the risk of recurrence may not depend on the anatomical appearance of the labrum alone.

Optimization of bone-block positioning in the Bristow-Latarjet procedure: A biomechanical study

BackgroundIn the Bristow-Latarjet procedure, optimal positioning of the coracoid bone-block on the anterior aspect of the glenoid (standing or lying on the glenoid rim) remains debated. A biomechanical study assessed the effect of the position of the bone-block with its attached conjoint tendon on anterior and inferior stabilization of the humeral head. Materials and methodsThe Bristow-Latarjet procedure was performed on 8 fresh cadaveric shoulders. The bone-block size was systematically at 2.5×1×1cm. Anterior translation of the humeral head was stress induced under 30-N traction, in maximum external rotation at 0° and at 90° abduction: respectively, adduction and external rotation (ADER), and abduction and external rotation (ABER). Under radiological control, displacement of the center of the humeral head was compared with the glenoid surface at the 3, 4 and 5 o’clock (medial, antero-inferior and inferior) positions for the 2 bone-block positionings. ResultsThe lying position at 4 o’clock substantially decreased anterior and inferior displacement of the humeral head respectively in ADER and ABER; and in ABER it also tended to decrease anterior translation, but not significantly. The standing bone-block position did not affect translation. ConclusionsPositioning the bone-block so that it lies on the anterior aspect of the glenoid in the middle of the antero-inferior quarter of the rim at 4 o’clock can decrease anterior displacement of the humeral head and inferior glenohumeral translation, especially in ADER for anterior displacement and in ABER for inferior displacement. Study designLaboratory study.

Case Report: Thoracic Outlet Syndrome in an Elite Archer in Full-draw Position

One possible pathomechanism of thoracic outlet syndrome (TOS) is shoulder abduction and extension inducing backward motion of the clavicle which causes compression on the brachial plexus. This position occurs during the full-draw stage of archery, by drawing and holding the bowstring. A 28-year-old elite archer presented with a feeling of weakness and dull shoulder pain, and experienced decreased grip power and hypoesthesia in the ulnar nerve dermatome in the full-draw position. On CT angiography, the cross-sectional area of the subclavian artery in the costoclavicular space decreased to 40% compared with that of the subclavian artery in a noncompressed state. This patient had first rib resection through the supraclavicular approach with a clavicle osteotomy. At 3.5 years postoperatively, the patient maintained his job as a professional coach and did not have any specific complaints when teaching and demonstrating archery skills. A literature review revealed numerous causes of TOS, ranging from congenital abnormalities to repetitive postures related to sports activities. The abduction and external rotation (ABER) position (shoulder at 90° abduction and external rotation) has been suggested for detecting TOS and is a documented cause of compression of the brachial plexus and subclavian vessels. We present the case of an archer with TOS association with repeated use of the ABER position. TOS should be suspected when athletes repeatedly use shoulder extension and abduction for their sports if other pathologic conditions can be ruled out.

The added value of ABER position for the detection and classification of anteroinferior labroligamentous lesions in MR arthrography of the shoulder

PurposeThe purpose of this study is to compare MR arthrography in abduction and external rotation (ABER) position with conventional MR arthrography in neutral position for the detection and further classification of anteroinferior labroligamentous lesions. Materials and methodsTwo hundred and twenty-nine cases of shoulder MR arthrography with subsequent arthroscopy were retrospectively evaluated. All MR arthrograms in ABER position and neutral position were independently assessed by two radiologists who were blinded to the arthroscopic findings. Sensitivities and specificities of both positions for detection and further categorization of anteroinferior labroligamentous lesions were calculated and compared using paired McNemar test. K values were calculated to quantify the level of interobserver agreement. ResultsAt arthroscopy, 24 Bankart lesions, 59 ALPSA lesions, 39 Perthes lesions, 8 GLAD lesions, 4 ALIPSA lesions, 31 nonclassifiable lesions and 60 intact anteroinferior complexes were found. The sensitivity of MR arthrography in ABER position for detecting anteroinferior labroligamentous lesions was significantly higher than that of in neutral position (92.7–94.5% versus 81.8–83%, P<0.05). For the detection rate of the mentioned 6 subtypes of lesions, only the Perthes lesions had significant improvement in ABER position when compared with conventional MR arthrography (observer 1, 61.5–87.2%, P=0.006; observer 2, 69.2–92.3%, P=0.004). MR arthrography in ABER position was more effective in identifying of Perthes lesions (66.7–74.4% versus 35.9–40%, P<0.05) while the conventional MR arthrography was more effective in accurate diagnose of ALPSA lesions (74.6–78.0% versus 54.2–55.9%, P<0.05). No statistically significant difference of the diagnostic accuracy was found between the two positions for Bankart lesions, GLAD lesions, and ALIPSA lesions. ConclusionMR arthrography in ABER position has more added value on detection of Perthes lesions in evaluation of anteroinferior labroligamentous complex tear.

Occlusion and stenosis of the posterior circumflex humeral artery: Detection with ultrasound in a normal population

The posterior circumflex humeral artery (PCHA) travels together with the axillary nerve through the quadrilateral space of the shoulder. Angiographic occlusion of this artery upon abduction and external rotation (ABER) of the arm has been accepted as evidence of mechanical compression of the axillary nerve and thus considered pathognomonic of quadrilateral space syndrome (QSS). The specificity of this sign for QSS has however been called into question as there are, to date, limited data on the incidence of axillary neurovascular compression during ABER in a normal population. We set out to determine the rate of stenosis or occlusion of the PCHA on ABER in healthy volunteers using ultrasound. Healthy volunteers asymptomatic for shoulder complaints were recruited from patients attending the clinic for ultrasound imaging not related to the shoulder, as well as volunteers among staff. Doppler sampling of the PCHA of both shoulders of participants was conducted in neutral and abduction and externally rotated positions. Each shoulder was treated as a separate entity. Results showed that 15/93 (16%) of shoulders demonstrated Doppler ultrasound evidence of occlusion or significant stenosis in the absence of shoulder complaints. Occlusion or stenosis of the PCHA on ABER is an uncommon finding in an asymptomatic population. Axillary neurovascular compression is unlikely if colour Doppler ultrasound does not show PCHA compromise during ABER.

Magnetic resonance arthrography including aber view in diagnosing partial-thickness tears of the rotator cuff: Accuracy, and inter- and intra-observer agreements

Partial-thickness tear of the rotator cuff is a common cause of shoulder pain. Magnetic resonance (MR) arthrography has been described as a useful measure to diagnose rotator cuff abnormalities. To determine the reliability and accuracy of MR arthrography with abduction and external rotation (ABER) view for the diagnosis of partial-thickness tears of the rotator cuff. Among patients who underwent MR arthrographies, 22 patients (12 men, 10 women; mean age 45 years) who had either partial-thickness tear or normal tendon on arthroscopy were included. MR images were independently scored by two observers for partial-thickness tears of the rotator cuff. Interobserver and intraobserver agreements for detection of partial-thickness tears of the rotator cuff were calculated by using kappa coefficients. The differences in areas under the receiver operating characteristic (ROC) curves were assessed with a univariate Z-score test. Differences in sensitivity and specificity for interpretations based on different imaging series were tested for significance using the McNemar statistic. Sensitivity, specificity, and accuracy of each reader on MR imaging without ABER view were 83%, 90%, and 86%, and 83%, 80%, and 82%, respectively, whereas on overall interpretation including ABER view, the sensitivity, specificity, and accuracy of each reader were 92%, 70%, and 82%, and 92%, 80%, and 86%, respectively. Including ABER view, interobserver agreement for partial-thickness tear increased from kappa=0.55 to kappa=0.68. Likewise, intraobserver agreements increased from kappa=0.79 and 0.53 to kappa=0.81 and 0.70 for each reader, respectively. The areas under the ROC curves for each reader were 0.96 and 0.90, which were not significantly different. Including ABER view in routine sequences of MR arthrography increases the sensitivity, and inter- and intraobserver agreements for detecting partial-thickness tear of rotator cuff tendon.

Rotator cuff tears: should abduction and external rotation (ABER) positioning be performed before image acquisition? A CT arthrography study

To evaluate the impact of abduction and external rotation (ABER) positioning performed before image acquisition on the assessment of rotator cuff tears. Twenty-seven consecutive patients with clinically suspected rotator cuff tears underwent an initial CT arthrogram of the shoulder in neutral position, immediately followed by temporary ABER positioning, before a second CT acquisition in neutral position. Two observers blinded to potential pre-procedure ABER positioning independently analysed the randomly distributed images. Lesions were classified into partial-thickness (PT) and full-thickness (FT) tear subtypes. Lesion detection and measurements of pre- and post-ABER studies were compared. We found no influence of pre-test ABER positioning on FT detection or measurements. Every PT detected on pre-ABER study was also detected on post-ABER study (28/28 for reader 1, and 32/32 for reader 2). Seven and eight additional PT were found by readers 1 and 2, respectively, on post-ABER study. Lesion size increased after ABER in terms of area (P < 0.001 for both readers) and Ellman's grade (P = 0.02 and 0.002 for reader 1 and 2, respectively). ABER positioning before CT is associated with improved delineation of partial tears, a higher number of detected tears and modification of treatment planning.

Transverse Thickening Along the Articular Surface of the Rotator Cuff Consistent With the Rotator Cable: Identification With MR Arthrography and Relevance in Rotator Cuff Evaluation

The purposes of this study were to describe the imaging appearance of transverse thickening along the articular surface of the supraspinatus and infraspinatus tendons presumed to represent the rotator cable on MR arthrographic images obtained with the shoulder in abduction and external rotation (ABER) and in the non-ABER position and to assess the role of the rotator cable in the diagnosis of rotator cuff tears. The study group comprised 54 patients who underwent arthroscopy of the shoulder and preoperative MR arthrography in which ABER images were obtained. Two blinded reviewers independently examined the ABER and non-ABER images for the presence of the rotator cable and rotator cuff tears. In intact rotator cuffs, the presumed rotator cable was not well visualized on non-ABER images. In one case of prominent rotator cable, MR arthrography showed no tear on non-ABER images, but at arthroscopy, a partial-thickness undersurface tear was found. On non-ABER images, both readers readily visualized the rotator cable in eight and 10 of 18 cases (44% and 56%) of partial-thickness undersurface tear and four of five cases (80%) of full-thickness tear. On ABER images, both readers readily visualized the rotator cable in 15 and 17 of 31 cases (48% and 55%) of intact cuff, 14 and 15 of 18 cases (78% and 83%) of undersurface tear, and four and five cases (80% and 100%) of full-thickness tear. Interobserver agreement on cable visualization was almost perfect (kappa = 0.86). On non-ABER MR arthrographic images, thickening along the articular side of the supraspinatus and infraspinatus tendons presumed to represent the rotator cable suggests the presence of a partial-thickness rotator cuff tear. On ABER images, the cable is well defined in intact and torn rotator cuffs.

Abduction and External Rotation in Shoulder Impingement: An Open MR Study on Healthy Volunteers—Initial Experience

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. 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 degrees abduction and in a loaded ABER position, with a 1-kg load that produced an average external rotation of 111 degrees+/-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. 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). 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.

Injuries of anterior glenoid labrum:evaluation with MR arthrography

Objective To determine the diagnostic value of shoulder MR arthrography in revealing the injuries of anterior glenoid labrum,and to compare MR arthrography with arm in neutral position with MR arthrography with arm in abduction and external rotation(ABER)position.Methods MR arthrography of the shoulder,including additional oblique axial sequences with the patient in the ABER position,was performed in 44 patients.The injuries of anterior glenoid labrum of these patients were retrospectively evaluated.The result was compared with that of arthroscopy.Results For displaying the abnormalities of anterior glenoid labrum,the sensitivity,specificity,and accuracy of axial MR images with arm in neutral position were 79.3%(23/29),100%(15/15),and 86.4%(38/44),respectively.While the results of ABER position oblique axial images were 93.1%(27/29),100%(15/15),and 95.5%(42/44), respectively.The difference of sensitivity between axial and ABER-position scans was statistically significant (P0.05).Conclusion MR arthrography with shoulder in the ABER position is more sensitive than conventional axial scanning in diagnosing the injuries of anterior glenoid labrum.

Indirect MR Arthrography of the Shoulder: Use of Abduction and External Rotation to Detect Full- and Partial-Thickness Tears of the Supraspinatus Tendon

To evaluate prospectively the accuracy of indirect magnetic resonance (MR) arthrography for supraspinatus tendon tears during neutral positioning or abduction and external rotation (ABER) and neutral positioning. Informed consent was obtained in all patients, and the study was approved by the institutional review board. Indirect MR arthrography of the shoulder was performed in 51 symptomatic patients (14 female, 37 male; mean age, 47 years) in the neutral position (set 1) and in the neutral and ABER positions (set 2). Two readers independently interpreted both sets, and diagnoses were compared with arthroscopic findings. Diagnostic accuracy was calculated, and 95% confidence intervals were used to detect significant differences between sets. Diagnostic confidence was recorded by using a three-level confidence score. Differences between sets were evaluated by using the Wilcoxon signed rank test. Interobserver agreement was determined separately for each set and for all diagnoses, full-thickness tears, and partial-thickness tears. For full-thickness tears, there was no benefit to reading set 2. For reader 1, sensitivity and specificity were 95% and 100%, respectively, for set 1 and 100% and 100%, respectively, for set 2. For reader 2, sensitivity and specificity were 80% and 100%, respectively, for set 1 and 100% and 100%, respectively, for set 2. For partial-thickness tears, sensitivity was significantly higher after reading set 2. For reader 1, sensitivity and specificity were 71% and 88%, respectively, for set 1 and 93% and 100%, respectively, for set 2. For reader 2, sensitivity and specificity were 50% and 88%, respectively, for set 1 and 86% and 94%, respectively, for set 2. For both readers, diagnostic confidence for partial-thickness tears was significantly higher after reading set 2. After the interpretation of set 2, kappa values increased from 0.35 to 1.00 for full-thickness tears and from 0.12 to 0.63 for partial-thickness tears. Indirect MR arthrography with supplementary images obtained with patients in the ABER position significantly improved sensitivity and increased diagnostic confidence for partial-thickness tears of the supraspinatus tendon. Interobserver agreement was improved for both full- and partial-thickness tears.