Arthroscopic release of the rotator interval and coracohumeral ligament: An anatomic study in cadavers

The puzzling pathophysiology of frozen shoulders - a scoping review

Purpose

The pathophysiology of frozen shoulders is a complex and multifactorial process. The purpose of this review is to scope the currently available knowledge of the pathophysiology of frozen shoulders.

Methods

A systematic search was conducted in Medline, Embase and the Cochrane library. Original articles published between 1994 and October 2020 with a substantial focus on the pathophysiology of frozen shoulders were included.

Results

Out of 827 records, 48 original articles were included for the qualitative synthesis of this review. Glenohumeral capsular biopsies were reported in 30 studies. Fifteen studies investigated were classified as association studies. Three studies investigated the pathophysiology in an animal studies. A state of low grade inflammation, as is associated with diabetes, cardiovascular disease and thyroid disorders, predisposes for the development of frozen shoulder. An early immune response with elevated levels of alarmins and binding to the receptor of advance glycation end products is present at the start of the cascade. Inflammatory cytokines, of which transforming growth factor-β1 has a prominent role, together with mechanical stress stimulates Fibroblast proliferation and differentiation into myofibroblasts. This leads to an imbalance of extracellular matrix turnover resulting in a stiff and thickened glenohumeral capsule with abundance of type III collagen.

Conclusion

This scoping review outlines the complexity of the pathophysiology of frozen shoulder. A comprehensive overview with background information on pathophysiologic mechanisms is given. Leads are provided to progress with research for clinically important prognostic markers and in search for future interventions.

Level of evidence

Level V.

Optimal Cut-Off Value of the Coracohumeral Ligament Area as a Morphological Parameter to Confirm Frozen Shoulder

BACKGROUND

Thickened coracohumeral ligament (CHL) is one of the important morphological changes of frozen shoulder (FS). Previous research reported that coracohumeral ligament thickness (CHLT) is correlated with anterior glenohumeral instability, rotator interval and eventually FS. However, thickness may change depending on the cutting angle, and measurement point. To reduce measurement mistakes, we devised a new imaging criteria, called the coracohumeral ligament area (CHLA).

METHODS

CHL data were collected and analyzed from 52 patients with FS, and from 51 control subjects (no evidence of FS). Shoulder magnetic resonance imaging was performed in all subjects. We investigated the CHLT and CHLA at the maximal thickened view of the CHL using our picture archiving and communications system. The CHLA was measured as the whole area of the CHL including the most hypertrophied part of the MR images on the oblique sagittal plane. The CHLT was measured at the thickest point of the CHL.

RESULTS

The average CHLA was 40.88 ± 12.53 mm² in the control group and 67.47 ± 19.88 mm² in the FS group. The mean CHLT was 2.84 ± 0.67 mm in the control group and 4.01 ± 1.11 mm in the FS group. FS patients had significantly higher CHLA (P < 0.01) and CHLT (P < 0.01) than the control group. The receiver operator characteristic analysis showed that the most suitable cut-off score of the CHLA was 50.01 mm², with 76.9% sensitivity, 76.5% specificity, and area under the curve (AUC) of 0.87. The most suitable cut-off value of the CHLT was 3.30 mm, with 71.2% sensitivity, 70.6% specificity, and AUC of 0.81.

CONCLUSION

The significantly positive correlation between the CHLA, CHLT and FS was found. We also demonstrate that the CHLA has statistically equivalent power to CHLT. Thus, for diagnosis of FS, the treating physician can refer to CHLA as well as CHLT.

Ultrasound-guided coracohumeral ligament release

Long-term follow-up of patients with adhesive capsulitis (AC) reveals that approximately half of them suffer from a limited range of shoulder motion, particularly external and/or internal rotation. We report the surgical technique and short-term clinical outcomes of ultrasound-guided release of the thickened coracohumeral (CH) ligament in 8 patients (9 shoulders) with AC. Passive external rotation with the arm by the side significantly increased from an average of 18° preoperatively to 47° immediately after CH ligament release. VAS and ASES scores were improved at 3months follow-up in all 9 shoulders, and maintained at 6months follow-up in 6 shoulders. No procedure-related adverse events developed over the 6-month follow-up period. Ultrasound-guided release for thickened CH ligament is a reliable and effective minimally invasive surgery for persistent limited external rotation due to AC of the shoulder.

Correlations of coracohumeral ligament and range of motion restriction in patients with recurrent anterior glenohumeral instability evaluated by magnetic resonance arthrography

BACKGROUND

Evaluation of range of motion (ROM) restriction before treatment of shoulder disorders is important for predicting the final functional outcomes. The purpose of this study was to investigate correlations of thickness of the coracohumeral ligament (CHL) and ROM restriction in patients with recurrent anterior glenohumeral instability.

METHODS

Between January 2005 and March 2015, 181 shoulders (137 male and 44 female patients; mean age, 29.3 years) with recurrent anterior glenohumeral instability treated with an arthroscopic Bankart repair were enrolled in this study. We evaluated preoperative ROM, thickness of the CHL, and obliteration of the subcoracoid fat triangle on magnetic resonance arthrography. ROM measurements, including forward flexion (FF), external rotation with the arm at the side (ER), and hand behind the back (HBB), were made in a standing position.

RESULTS

There were significant negative correlations between FF and age (P < .001) and between HBB and age (P < .001) but not between ER and age (P = .11). The thickness of the CHL significantly increased with age (P < .001). FF, ER, and HBB were significantly restricted in patients with obliteration compared with those without obliteration (P < .001, P = .004, P < .001, respectively).

CONCLUSIONS

Obliteration of the subcoracoid fat triangle and the thickness of the CHL positively correlated with ROM restrictions, and these changes were greater with age in patients with recurrent anterior glenohumeral instability.

Arthroscopic extended rotator interval release for treating refractory adhesive capsulitis

PURPOSE

To present the clinical results of arthroscopic extended rotator interval release with a stretching program for treating refractory adhesive capsulitis.

STUDY DESIGN

Case series; level of evidence, 4.

METHODS

Arthroscopy-assisted extended rotator interval tissue release including anterior capsular was performed in 26 patients with refractory adhesive capsulitis. All rotator interval tissues, except the medial sling of the biceps, were excised and the excursion of the subscapularis tendon was restored and freely mobilized. The preoperative mean passive forward flexion was 101°, whereas external rotation at the side was 10°. Patients were followed for a minimum of 2 years and their visual analog scale for pain, muscle power, range of motion, Constant score, modified American Shoulder and Elbow Surgeons Shoulder Evaluation Form score, and modified University of California at Los Angeles score were recorded.

RESULTS

Visual pain scale and the aforementioned clinical scores improved postoperatively. The patients exhibited a significant postoperative difference in forward flexion, external rotation, and internal rotation. Postoperative mean passive forward flexion was 172°, whereas external rotation at the side was 58°. There was no difference in the muscle power postoperatively including abduction, internal rotation, and external rotation.

CONCLUSIONS

Our study revealed satisfactory subjective and objective clinical results after a 2-year follow-up. Arthroscopy-assisted extended rotator interval release with a stretching program could be an alternative treatment for refractory adhesive capsulitis.

Arthroscopic anatomy of the subdeltoid space

From the first shoulder arthroscopy performed on a cadaver in 1931, shoulder arthroscopy has grown tremendously in its ability to diagnose and treat pathologic conditions about the shoulder. Despite improvements in arthroscopic techniques and instrumentation, it is only recently that arthroscopists have begun to explore precise anatomical structures within the subdeltoid space. By way of a thorough bursectomy of the subdeltoid region, meticulous hemostasis, and the reciprocal use of posterior and lateral viewing portals, one can identify a myriad of pertinent ligamentous, musculotendinous, osseous, and neurovascular structures. For the purposes of this review, the subdeltoid space has been compartmentalized into lateral, medial, anterior, and posterior regions. Being able to identify pertinent structures in the subdeltoid space will provide shoulder arthroscopists with the requisite foundation in core anatomy that will be required for challenging procedures such as arthroscopic subscapularis mobilization and repair, biceps tenodesis, subcoracoid decompression, suprascapular nerve decompression, quadrangular space decompression and repair of massive rotator cuff tears.

The rotator interval and long head biceps tendon: anatomy, function, pathology, and magnetic resonance imaging

The rotator interval is an anatomically defined triangular area located between the coracoid process, the superior aspect of the subscapularis, and the anterior aspect of the supraspinatus. It is widely accepted that the rotator interval structures fulfill a role in biomechanics and pathology of the glenohumeral joint and long head biceps tendon. However, there is ongoing debate regarding the biomechanical details and the indications for treatment. A better understanding of rotator interval anatomy and function will lead to improved treatment of rotator interval abnormalities, and guide the indications for imaging and surgical intervention.

Multimedia article. The rotator interval: pathology and management

The rotator interval describes the anatomic space bounded by the subscapularis, supraspinatus, and coracoid. This space contains the coracohumeral and superior glenohumeral ligament, the biceps tendon, and anterior joint capsule. Although a definitive role of the rotator interval structures has not been established, it is apparent that they contribute to shoulder dysfunction. Contracture or scarring of rotator interval structures can manifest as adhesive capsulitis. It is typically managed nonsurgically with local injections and gentle shoulder therapy. Recalcitrant cases have been successfully managed with an arthroscopic interval release and manipulation. Conversely, laxity of rotator interval structures may contribute to glenohumeral instability. In some cases this can be managed with one of a number of arthroscopic interval closure techniques. Instability of the biceps tendon is often a direct result of damage to the rotator interval. Damage to the biceps pulley structures can lead to biceps tendon subluxation or dislocation depending on the structures injured. Although some authors describe reconstruction of this tissue sling, most recommend tenodesis or tenotomy if it is significantly damaged. Impingement between the coracoid and lesser humeral tuberosity is a relatively well-established, yet less common cause of anterior shoulder pain. It may also contribute to injury of the anterosuperior rotator cuff and rotator interval structures. Although radiographic indices are described, it appears intraoperative dynamic testing may be more helpful in substantiating the diagnosis. A high index of suspicion should be used in association with biceps pulley damage or anterosuperior rotator cuff tears. Coracoid impingement can be treated with either open or arthroscopic techniques. We review the anatomy and function of the rotator interval. The presentation, physical examination, imaging characteristics, and management strategies are discussed for various diagnoses attributable to the rotator interval. Our preferred methods for treatment of each lesion are also discussed.

Stretching positions for the coracohumeral ligament: Strain measurement during passive motion using fresh/frozen cadaver shoulders

BACKGROUND

Contracture of the coracohumeral ligament is reported to restrict external rotation of the shoulder with arm at the side and restrict posterior-inferior shift of the humeral head. The contracture is supposed to restrict range of motion of the glenohumeral joint.

METHODS

To obtain stretching position of the coracohumeral ligament, strain on the ligament was measured at the superficial fibers of the ligament using 9 fresh/frozen cadaver shoulders. By sequential measurement using a strain gauge, the ligament strain was measured from reference length (L0). Shoulder positions were determined using a 3 Space Tracker System. Through a combination of previously reported coracohumeral stretching positions and those observed in preliminary measurement, ligament strain were measured by passive external rotation from 10° internal rotation, by adding each 10° external rotation, to maximal external rotation.

RESULTS

Stretching positions in which significantly larger strain were obtained compared to the L0 values were 0° elevation in scapula plane with 40°, 50° and maximum external rotation (5.68%, 7.2%, 7.87%), 30° extension with 50°, maximum external rotation (4.20%, 4.79%), and 30° extension + adduction with 30°, 40°, 50° and maximum external rotation (4.09%, 4.67%, 4.78%, 5.05%)(P < 0.05). No positive strain on the coracohumeral ligament was observed for the previously reported stretching positions; ie, 90° abduction with external rotation or flexion with external rotation.

CONCLUSIONS

Significant strain of the coracohumeral ligament will be achieved by passive external rotation at lower shoulder elevations, extension, and extension with adduction.

Adhesive capsulitis of the shoulder: dimensions of the rotator interval measured with magnetic resonance arthrography

BACKGROUND

This study was performed to define the dimensions of the rotator interval (RI) in adhesive capsulitis using magnetic resonance (MR) arthrography preoperatively to clarify and evaluate pathology.

METHODS

We performed a retrospective review of a series of 73 shoulders that underwent MR arthrography. The shoulders were grouped according to their diagnosis: group I comprised 47 shoulders without adhesive capsulitis; group II comprised 26 shoulders with adhesive capsulitis. Using MR arthrography, we estimated the height, base, RI area, width, RI index, and RI ratio.

RESULTS

The group II shoulders differed significantly in height, base, RI area, RI index, and RI ratio from the group I shoulders. There were statistically significant differences in RI dimensions between patients with and without adhesive capsulitis of the shoulder.

CONCLUSIONS

Estimating the dimensions of the RI in adhesive capsulitis using MR arthrography may prove to be valuable for assessing patients preoperatively.

An anatomic and histologic study of the coracohumeral ligament

Although the anatomy and histology of the coracohumeral ligament (CHL) play an important role in the diagnosis and treatment of frozen shoulder, they remain unclear. Our objective was to study the anatomic features of the CHL and analyze its histology. Twenty-six fresh-frozen, normal cadaveric shoulders were used to examine the position and morphology of the CHL and their relationship with the superior glenohumeral ligament and to determine the CHL's histologic features in comparison with the joint capsule and coracoacromial ligament. The CHLs were all located in the rotator interval, with an irregular trapezoidal structure. The subacromial bursa was above the CHL, and the subcoracoid bursa was below the it. The CHLs in all shoulders originated from the lateral aspect of the base of the coracoid process. In 11 shoulders, it inserted into the supraspinatus tendon, whereas in 11 other shoulders, it inserted into the rotator interval. In 3 shoulders, the CHLs were split and inserted into both the supraspinatus and subscapularis tendons, respectively. Finally, the CHL in 1 shoulder only inserted into the subscapularis tendon. We also observed that the pectoralis minor tendons in 4 shoulders passed over the coracoid process top and inserted into the CHLs. In 11 shoulders, a complex of the CHL and the superior glenohumeral ligament was formed. Histologically, the CHL was found to be similar to the joint capsule without any ligament features. The position, morphology, and origin of the CHL did not change much, but its insertion varied greatly. In addition, the CHL had the histologic feature of a capsule, not a ligament.

Biomechanics and anatomy of the proximal biceps tendon

With the role of the biceps tendon being the source of considerable controversy, the treatment of its disease has been even more confusing. Our understanding of its role in shoulder pathology has ranged from describing it as a vestigial structure, to a vital structure of shoulder function with distinct disease pathology. This chapter analyzes the anatomic and biomechanical functions of the proximal biceps tendon.

An analysis of the rotator interval in patients with anterior, posterior, and multidirectional shoulder instability

PURPOSE

To describe anatomic measurements of the rotator interval (RI) on magnetic resonance arthrogram (MRA) images and to assess the relationship between increased dimensions of the RI and instability conditions of the shoulder.

METHODS

Three groups of patients with clinical instability were treated arthroscopically (anterior [A = 19 patients], posterior [P = 14 patients], and multidirectional [M = 13 patients]), and a group of 10 control patients without clinical instability were also identified. The MRAs of all groups were randomized, and 5 blinded reviewers recorded RI anatomic measurements of: (1) sagittal measures of the distance between the subscapularis (SSc) and supraspinatus (SS) tendons at 3 anatomic landmarks across the RI, and (2) the sagittal position of the long head of the biceps (LHB) relative to the most anterior aspect of the SS.

RESULTS

The rotator interval distance between the SS and SSc tendons was nearly identical for all groups of instability, and was also not different from control groups. On the sagittal oblique sequences, the distance from the LHB tendon to the anterior edge of the SS tendon was significantly increased in posterior (7.4 mm) instability versus both the control group (2.4 mm; P = .025) and those with anterior instability (4.5 mm; P = .041), with the LHB in a consistent anterior position. The remainder of the measures was not statistically different between the groups.

CONCLUSIONS

The distance between the SS and SSc and the overall size of the RI was well preserved in all instability patterns and control conditions. The LHB tendon assumes a more anterior position relative to the supraspinatus tendon in patients with posterior instability versus those patients with anterior instability or those without clinical instability. Additional work is necessary to further define objective radiographic evidence of RI insufficiency in patients with shoulder instability.

LEVEL OF EVIDENCE

Level III, prognostic case-control study.

Rotator interval dimensions in different shoulder arthroscopy positions: a cadaveric study

The rotator interval was defined as a triangular structure, where the base of the triangle was the coracoid base, the upper border was the anterior margin of the supraspinatus, and the lower border was the superior margin of the subscapularis muscle-tendon unit. We evaluated the rotator interval dimensions in 15 shoulders from 10 lightly embalmed adult cadavers in 3 shoulder arthroscopy positions: 0 degrees of abduction and 30 degrees of flexion (beach chair [BC]), 45 degrees of abduction and 30 degrees of flexion (lateral decubitus 1), and 70 degrees of abduction and 30 degrees of flexion (lateral decubitus 2). In each shoulder position, measurements were made in neutral rotation (NR), 45 degrees of external rotation (ER), and 45 degrees of internal rotation (IR). The coracoid base lengthened with IR in all positions and shortened in ER in the lateral decubitus position but not in the BC position. Abduction significantly lengthened the coracoid base, which was shortest in the BC position with ER (24 +/- 4 mm) and longest in the lateral decubitus 2 position with IR (33 +/- 5 mm). The coracoid base, where sutures are placed during plication of the interval, was observed to lengthen and, therefore, loosen with IR and abduction. To prevent postoperative ER restriction, plication should be made in ER or neutral rotation when operating in the BC position and the degree of abduction should be decreased and the shoulder held in ER when operating in the lateral decubitus position.

Variations in the superior capsuloligamentous complex and description of a new ligament

Although the rotator cuff interval and the adjacent ligaments are gaining interest because of their importance for glenohumeral instability and adhesive capsulitis, there seems to be some confusion about their anatomy. This study reinvestigates the superior capsular structures in 110 cadaveric shoulders by a combination of arthroscopy, dissection, histology, and functional analysis. The structure of the superior capsule was found to be more complex than suspected until now. The coracohumeral, coracoglenoid, and superior glenohumeral ligaments joined with a circular transverse band to form the anterior limb of a suspension sling. This was 9 to 26 mm wide at its midportion. In 90% of the specimens, there also was a posterior limb composed of a broad fibrous sheet, 6 to 26 mm wide at its midportion. This hitherto unrecognized posterosuperior glenohumeral ligament joined posterolaterally with the circular transverse band. Four types of configuration for the superior complex could be identified. The suspension sling formed by the superior complex functions in the same way as the hammock formed by the inferior glenohumeral ligament complex. The posterior limb seems to restrict internal rotation, like the anterior limb restricts external rotation. The expanded knowledge of the superior capsular complex increases the understanding of the pathology involved in anterosuperior and posterosuperior impingement, as well as articular-sided rotator cuff tears. It also has clinical implications for rotator cuff interval and biceps pulley lesions, because these areas are bordered by the anterior limb of the superior complex, as well as for adhesive capsulitis, where we can now understand why internal rotation is limited and why the release needs to be extended posterosuperiorly.

Arthroscopic versus open rotator interval closure: biomechanical evaluation of stability and motion

PURPOSE

The purposes of this study were to investigate the differences between open and arthroscopic closure of the rotator interval (RI) on glenohumeral translation and range of motion. We also sought to determine if the addition of either an open or arthroscopic RI closure increases stability of the shoulder.

METHODS

Fourteen fresh-frozen (10 paired) cadaveric shoulder specimens were mounted in a custom testing apparatus, and glenohumeral translation and rotation were obtained by using an optoelectric tracking system (Optotrak Certus; Northern Digital, Ontario, Canada). Specimens were randomly allocated to either open (n = 7) or arthroscopic (n = 7) plication of the RI. The following were measured first with an intact and vented specimen and subsequently after an RI closure using either open or arthroscopic techniques: (1) range of motion in neutral and 90 degrees abduction; (2) anterior and posterior translation at neutral rotation; (3) anterior translation at 90 degrees abduction with external rotation; and (4) posterior translation at 90 degrees flexion with internal rotation.

RESULTS

Posterior stability was not improved from the intact state by either open (1.0-mm change) or arthroscopic (0.1-mm change) repair. The sulcus stability was improved in the open group (5.7 mm to 2.9 mm, P = .028), but not arthroscopically (5.1 to 4.1 mm, P = .499). Neutral anterior stability was improved after open repair (7.2 to 2.6 mm, P = .018), but not arthroscopically (2.3 to 2.4 mm, P = 0.5). However, anterior stability in external rotation (ER) at 90 degrees abduction was improved in the arthroscopic repair group (5.5 to 3.1 mm, P = .006). The mean loss of ER in neutral was greater in the open group (40.8 degrees) versus the arthroscopic group (24.4 degrees, P = .0038). The arthroscopic group showed an 11.7 degrees loss of ER in 90 degree abduction (P = .018) versus the open group loss of 4.8 degrees. There were no significant differences in loss of IR in either neutral or 90 degree abduction.

CONCLUSIONS

Posterior stability was not improved by either open or arthroscopic rotator interval repair, and sulcus stability only improved with the open technique. Anterior stability in neutral was improved after open repair and in the arthroscopic repair group with the arm abducted. There was a large loss of external rotation with both techniques.

CLINICAL RELEVANCE

This study suggests that arthroscopic RI closure adds little to the overall posterior and inferior stability of the shoulder joint, although anterior stability may be improved. There is a potentially large loss of external rotation after either repair method.

Magnetic resonance imaging findings associated with surgically proven rotator interval lesions

OBJECTIVE

To identify shoulder magnetic resonance imaging (MRI) findings associated with surgically proven rotator interval abnormalities.

MATERIALS AND METHODS

The preoperative MRI examinations of five patients with surgically proven rotator interval (RI) lesions requiring closure were retrospectively evaluated by three musculoskeletal-trained radiologists in consensus. We assessed the structures in the RI, including the coracohumeral ligament, superior glenohumeral ligament, fat tissue, biceps tendon, and capsule for variations in size and signal alteration. In addition, we noted associated findings of rotator cuff and labral pathology.

RESULTS

Three of three of the MR arthrogram studies demonstrated extension of gadolinium to the cortex of the undersurface of the coracoid process compared with the control images, seen best on the sagittal oblique images. Four of five of the studies demonstrated subjective thickening of the coracohumeral ligament, and three of five of the studies demonstrated subjective thickening of the superior glenohumeral ligament. Five of five of the studies demonstrated a labral tear.

CONCLUSIONS

The MRI arthrogram finding of gadolinium extending to the cortex of the undersurface of the coracoid process was noted on the studies of those patients with rotator interval lesions at surgery in this series. Noting this finding-especially in the presence of a labral tear and/or thickening of the coracohumeral ligament or superior glenohumeral ligament-may be helpful in the preoperative diagnosis of rotator interval lesions.

The rotator interval: anatomy, pathology, and strategies for treatment

Over the past two decades, it has become accepted that the rotator interval is a distinct anatomic entity that plays an important role in affecting the proper function of the glenohumeral joint. The rotator interval is an anatomic region in the anterosuperior aspect of the glenohumeral joint that represents a complex interaction of the fibers of the coracohumeral ligament, the superior glenohumeral ligament, the glenohumeral joint capsule, and the supraspinatus and subscapularis tendons. As basic science and clinical studies continue to elucidate the precise role of the rotator interval, understanding of and therapeutic interventions for rotator interval pathology also continue to evolve. Lesions of the rotator interval may result in glenohumeral joint contractures, shoulder instability, or in lesions to the long head of the biceps tendon. Long-term clinical trials may clarify the results of current surgical interventions and further enhance understanding of the rotator interval.

Arthroscopic rotator interval closure: effect of sutures on glenohumeral motion and anterior-posterior translation

BACKGROUND

The effect of arthroscopic rotator interval closure on glenohumeral motion and translation is not well understood, nor is the ideal location or number of sutures required for closure.

HYPOTHESIS

The number of arthroscopic rotator interval closure sutures and their placement will have a significant effect on glenohumeral range of motion and anterior-posterior translation.

STUDY DESIGN

Controlled laboratory study.

METHODS

Using a custom testing apparatus, the authors measured range of motion in 12 fresh-frozen cadaveric shoulders; anterior-posterior translation in adduction and neutral rotation was measured in 9. Specimens were initially tested without sutures and then tested after 3 interval closures using a random sequence of (1) an isolated medial suture at the level of the glenoid, (2) an isolated lateral suture 1 cm lateral to the glenoid, or (3) both sutures followed by removal of all sutures.

RESULTS

Analysis of variance demonstrated that interval closure had a significant effect on decreasing flexion (mean, 6 degrees), external rotation (mean, 10 degrees), and anterior translation (mean, 3 mm) of the adducted shoulder. There was no significant difference between the 3 interval closures in any of the tests.

CONCLUSION

Arthroscopic interval closure produced significant decreases in range of motion and anterior-posterior translation. The effects of single lateral or medial suture closures were similar to the use of 2 sutures.

CLINICAL RELEVANCE

This study suggests that the initial effect of arthroscopic rotator interval closure on anterior translation of the shoulder will be similar whether 1 or 2 sutures are used. In vivo studies are necessary to determine if the effect of these 2 methods would be the same over time.

The influence of arthroscopic subscapularis tendon and anterior capsular release on glenohumeral translation: a biomechanical model

The effect of an arthroscopic release of the intraarticular portion of the subscapularis tendon and the anterior capsule on glenohumeral translation was investigated in a cadaveric model. Ten human cadaveric shoulders with a mean age of 63.5 years (range, 52-79 years) were tested in a robot-assisted shoulder simulator. Joint translation was measured before and after an arthroscopic release of the intraarticular portion of the subscapularis tendon and a subsequent release of the anterior capsule at 0 degrees , 30 degrees , 60 degrees , and 90 degrees of glenohumeral elevation. Translation was measured in the anterior, anterior-inferior, and inferior directions under 20 N of applied load. Testing of the specimen revealed that the release of the intraarticular portion of the subscapularis tendon and the anterior capsule increased translation in all directions. Significant increases in translation were observed after release of the intraarticular portion of the subscapularis tendon in the midrange of motion. The influence of the arthroscopic capsular release, in conjunction with the release of the subscapularis tendon, was very high above 60 degrees of elevation. The study indicates that the intraarticular component of the subscapularis tendon functions as a restraint to anterior-inferior translation primarily in the midrange of glenohumeral motion, whereas the anterior capsule adds anterior-inferior stability to the glenohumeral joint mainly above 60 degrees of elevation.

MR Imaging of the Rotator Cuff Interval

The rotator cuff interval is defined as the space between the anterior aspect of the supraspinatus tendon and the superior aspect of the subscapularis tendon. Knowledge of the anatomy, an understanding of the commonly encountered pathology, and an approach for the systematic inspection of the rotator cuff interval is crucial for the accurate characterization and diagnosis of pathology of this region. This article reviews the basic normal anatomy of the rotator cuff interval, imaging considerations unique to this area, and commonly encountered pathology.

[Arthroscopic capsular release in the management of refractory adhesive capsulitis. Technique and results]

Idiopathic adhesive capsulitis can severely restrict the comfort and function of the entire extremity, often resulting in prolonged, substantial disability. Some studies have demonstrated long-term residual pain and limitation of motion in most patients after conservative treatment such as physical therapy or corticoid injection. Closed manipulation is associated with severe complications. We report the technique and results of arthroscopic capsular release as an effective and safe alternative for the management of refractory adhesive capsulitis. We operated 23 patients between June 2003 and November 2004 who suffered from a loss of glenohumeral motion in all planes arthroscopically. Ten of the patients were evaluated after a mean follow-up of 6 months. We found significant pain relief a few days after surgery in every patient. Furthermore, we found improvements in the range of motion in all planes. Abduction improved from preoperative 50 degrees to postoperative 120 degrees , flexion from 55 degrees to 120 degrees, external rotation from 10 degrees to 60 degrees and internal rotation from 20 degrees to 65 degrees. The average Constant Score improved from preoperative 32 to postoperative 81 points. Arthroscopic capsular release is an effective and safe technique for the management of refractory adhesive capsulitis, avoiding prolonged disability.

The dimensions of the rotator interval

The purpose of this study was to define the anatomy and dimensions of the rotator interval (RI). Thirty-two fresh-frozen cadaveric shoulders were thawed, all external musculature was removed, and coracoid osteotomy was performed to visualize the rotator cuff and RI. The 3 sides of the RI (triangle) were measured in dynamic glenohumeral positions (neutral and 45 degrees external and internal rotation). An arthroscopic posterior portal, without fluid distention, was used to visualize the RI, defects, and glenohumeral pathology. The RI was sectioned, and histologic analysis and thickness measurements were performed. The mean area of the RI was 414.46 mm(2) (95% confidence interval, 362.66-466.22 mm(2)), measured in neutral position. No statistically significant differences were measured between paired right and left shoulders; however, male specimens had a significantly larger base and area than the female specimens. The dimensions of the RI changed with glenohumeral motion. The RI is definable and dynamic with glenohumeral motion. The RI closes down with internal rotation and is opened up with external rotation. This change in the interval supports the idea that, if the arm is held in internal rotation during imbrication of the capsule, overtightening and a resulting loss of external rotation can occur.

Magnetic resonance imaging of shoulders with idiopathic adhesive capsulitis: reliability of measures

The magnetic resonance imaging (MRI) findings in idiopathic adhesive capsulitis (AC) were compared with those of contralateral healthy shoulders and the reliability of measures assessed. Twenty-six consecutive patients (26 AC and 14 healthy shoulders) were prospectively assessed. The main measurements were thickness of the joint capsule and synovial membrane in the axillary recess and rotator interval in T1-weighted spin-echo sequence enhanced with intravenous (IV) gadolinium chelate (Gd-chelate). Reliability was studied by use of the intraclass correlation coefficient (ICC). The mean thickness of the axillary recess on the coronal plane was 9.0+/-2.2 mm in AC shoulders and 0.4+/-0.7 mm in healthy shoulders. The mean thickness of the rotator interval on the sagittal plane was 8.4+/-2.8 in AC shoulders and 0.6+/-0.8 mm in healthy shoulders. Interobserver reliability was good for the axillary recess, with ICC values of 0.84 for the coronal plane, and good for the rotator interval, with ICC values of 0.80 for the sagittal plane. MRI with IV Gd-chelate injection can show, with acceptable reliability, signal and thickness abnormalities of the shoulder joint capsule and synovial membrane in AC.