The anatomy and histology of the rotator interval capsule of the shoulder

Dynamic pediatric shoulder instability: Etiology, pathogenesis and treatment

Dynamic shoulder instability in children or adolescents, whose glenohumeral growth plates are still open, is a rare condition with an etiology that is hard to decipher. Atraumatic and recurrent forms are most common, contrary to adults. Disruptions to capsule and ligament maturation, muscle balance or bone growth can lead to glenohumeral instability. The etiology assessment, which needs to be multidisciplinary in atraumatic forms, aims to collect the medical history, analyze the direction of the instability, determine whether it is voluntary or involuntary, and look for a history of trauma, connective tissue abnormality, psychological disorder, neuromuscular pathology or congenital malformation. The initial treatment is conservative. It requires a multidisciplinary team when the shoulder instability is voluntary. Surgical treatment is reserved for symptomatic forms that do not respond to conservative treatment and have an impact on daily life and/or sports participation after a minimum of 6 months of well-conducted rehabilitation. The results of surgical stabilization mainly depend on the features of the instability, the anatomical structures damaged and the etiology. Episodes of recurrent instability in children/adolescents with open glenohumeral growth plates can fade in adulthood or can get worse with the development of structural damage. Early detection of poor outcomes and suitable treatment will help to limit the occurrence of osteoarthritis in the medium and long term. LEVEL OF EVIDENCE: Expert opinion.

Imaging of the Long Head of Biceps Tendon and Rotator Interval

This article reviews the imaging and common pathology of the long head of biceps tendon and rotator interval (RI). This area of complex anatomy plays a crucial role in normal shoulder function. Injury or abnormality of the RI may contribute to a range of shoulder pathology, such as biceps instability, tendinopathy, and frozen shoulder. Understanding the normal and pathologic appearances of the RI structures is crucial for a correct diagnosis and directing treatment.

Assessing/Imaging the Subcoracoid Space: From Anatomy to Dynamic Sonography

In the pertinent literature, standardized sonographic protocols have been widely described to evaluate the different compartments of the shoulder. However, the subcoracoid space is a complex anatomical region-usually not included/described in basic ultrasound approaches. Accordingly, starting from its anatomy, we describe a two-phase dynamic ultrasound protocol to scan the subcoracoid space. This way, we aim to optimize the diagnosis and management of patients with anterior shoulder pain and subcoracoid effusion.

Post-surgical physiotherapy in frozen shoulder: A review

Despite its prevalence, the optimal management of frozen shoulder is unclear. A range of conservative measures are often undertaken with varying degrees of success. In cases of severe and persistent symptoms, release procedures which could include any combination of manipulation under anaesthetic, arthroscopic capsular release or hydrodilatation are frequently offered, none of which has been shown to offer superior outcome over the others. When surgical release is performed a period of rehabilitation is normally recommended but no best practice guidelines exist resulting in considerable variations in practice which may or may not directly affect patient outcome. During this narrative review, we hypothesise that these differing responses to treatment (both conservative and surgical options) are potentially the result of different causal mechanisms for frozen shoulder and may also suggest that post-release rehabilitation may need to take this into account.

The middle glenohumeral ligament: a classification based on arthroscopic evaluation

BACKGROUND

Although middle glenohumeral ligament (MGHL) variations have been shown in the literature, their clinical effect and relationship with intra-articular pathologies have yet to be revealed, except for the Buford complex. This study was designed to classify MGHL and to reveal its relationship with clinical pathologies.

METHODS

A total of 843 consecutive shoulder arthroscopies were evaluated retrospectively, and a classification system was proposed for MGHL with regard to its structure and its relation to the anterior labrum. The associations of each MGHL type with superior labrum anterior-posterior (SLAP) lesions, subscapularis tears, and anterior instability were investigated.

RESULTS

MGHL variations were grouped into 6 types according to the classification. A significant difference in favor of type 6 MGHL (Buford complex) was observed in the distribution of SLAP lesions (P < .001). There was no significant difference between MGHL types and the distribution of anterior instability history (P = .131) and subscapularis tears (P = .324).

CONCLUSION

SLAP lesions accompany type 6 MGHLs (Buford complex) significantly more frequently than other types. There is also a negative relation between the anterior instability and thicker MGHL variants.

Permeable spaces between glenohumeral ligaments as potential gateways for rapid regional anesthesia of the shoulder

Shoulder pain is a highly prevalent condition, often resulting in major life limitations, and requiring effective treatments. In this work, we explore the anatomical basis of a proposed approach to the regional anesthesia of the shoulder through a single injection under the subscapularis muscle. Bilateral experimental injections in shoulders from body donors (Radiolar ® and Methylene-Blue) under the subscapular muscle (n = 11) and cadaveric systematic dissections of other 35 shoulders from body donors were performed. Injectate spread was then qualitatively assessed. Long axis of permeable foramina in the anterior aspect of the shoulder joint capsule was measured in centimeters using a digital caliper. More than 40% of specimens had at least one permeable space (Weitbrech and/or Rouvière foramina) communicating the subscapular bursa and the articular space. We further demonstrate that an ultrasonography-guided injection under the subscapularis muscle allows the spread of the injectate through the anterior, inferior and posterodorsal walls of the articular capsule, the subacromial bursa, and the bicipital groove, as well as into the articular space for some injections. The odds of accidental intraarticular injection decrease when injecting with low volumes. This anatomical study provides a detailed description of foramina between glenohumeral ligaments. Furthermore, the data shown in this work supports, as a proof of concept, a safe alternative for rapid and specific blockade of terminal sensory branches innervating the shoulder joint capsule.

Arthroscopic anatomy of the middle glenohumeral ligament. A series of 300 cases

PURPOSE

The anatomy of the middle glenohumeral ligament (MGHL) is seldomly described during arthroscopy. The aim of this study was to determine the arthroscopic variants concerning the anatomy of the MGHL.

METHODS

A prospective, observational, single-center study was conducted between June 2016 and June 2017. All patients undergoing a first-time arthroscopy of the shoulder and with no history of prior surgery or trauma of the same shoulder were consecutively enrolled. The variations of the MGHLs shape and of its glenoid and distal insertions were documented during surgery.

RESULTS

A total 300 patients were included. Surgeries included rotator cuff sutures, tenotomy/tenodesis of the long head of the biceps tendon (LHBT) and subacromial decompression in respectively 31%, 32.7% and 35.5% of cases. The MGHL was absent in 12% of cases, presented a flat structure in 72% of cases, a cord-like shape in 14% and a Buford complex was observed in 1%. Its glenoid insertion was located on the labrum between the superior (SGHL) and inferior (IGHL) in 43% of cases, presented a combined insertion with the LHBT in 7%, with the SGHL in 29% and with both the SGHL and LHBT in 9%. The distal insertion was located in 67% of cases on the subscapularis tendon (SCCT) or the capsule covering it, and on the humeral bone in 21%.

CONCLUSION

This study confirms and details the anatomic variants of the MGHL, notably describing the lesser-known variants of its distal insertion, yet arises the question of the exact nature and function of this so-called ligament.

Posterior Shoulder Instability: What to Look for

Posterior shoulder instability is often hard to diagnose with clinical examination. Patients generally present with vague pain, weakness, and/or joint clicking but less frequently complaining of frank sensation of instability. Imaging examinations, especially MR imaging and magnetic resonance arthrography, have a pivotal role in the identification and management of this condition. This review describes the pathologic micro/macrotraumatic magnetic resonance features of posterior shoulder instability as well as the underlying joint abnormalities predisposing to this condition, including developmental anomalies of the glenoid fossa, humeral head, posterior labrum, and capsular and ligamentous structures.

Capsular Injury and Inflammation

The capsular and ligamentous structures of the glenohumeral joint are important for stability of the shoulder. These structures are best evaluated by MR imaging. Familiarity with normal and abnormal appearance of the capsular structures of the shoulder is important to ensure that important pathology is not overlooked. Injury to the capsular structures can occur in the setting of trauma and most commonly involves the inferior glenohumeral ligament and axillary pouch. Adhesive capsulitis is a common inflammatory condition with characteristic imaging features that should be considered in the absence of alternative diagnoses.

Rotator interval closure: inconsistent techniques and its association with anterior instability. A literature review

The Rotator interval (RI) is an anatomic space in the anterosuperior part of the glenohumeral joint. An incompetent or lax RI has been implicated in various conditions of shoulder instability and therefore RI has been frequently touted as an area that is important in preserving stability of the shoulder. Biomechanical studies have shown that repair of RI ligamentous and capsular structures decreases glenohumeral joint laxity in various directions. Clinical studies have reported successful outcomes after repair or plication of these structures in patients undergoing shoulder stabilization procedures. Although varieties of methods have been described for its closure, the optimal surgical technique is unclear with various inconsistencies in incorporation of the closure tissue. This in particular makes the analysis of the RI closure very difficult. The purposes of this study are to review the structures of the RI and their contribution to shoulder instability, to discuss the biomechanical and clinical effects of plication of RI structures in particular to anterior glenohumeral instability, to delineate the differences between an arthroscopic and open RI closure. Additionally, we have proposed a new classification system describing various techniques used during RI closure.

Outcomes After Arthroscopic Rotator Interval Closure for Shoulder Instability: A Systematic Review

PURPOSE

(1) To systematically assess the clinical outcomes of arthroscopic rotator interval closure (RIC) procedures for shoulder instability and (2) to report the different technical descriptions and surgical indications for this procedure.

METHODS

Two independent reviewers searched 4 databases (PubMed, Embase, Web of Science, and Cochrane) from database inception until October 15, 2017. The inclusion criteria were studies that reported outcomes of shoulder stabilization using arthroscopic RIC as an isolated or adjunctive surgical procedure. The methodologic quality of studies was assessed with the Methodological Index for Non-Randomized Studies tool and Grading of Recommendations Assessment, Development and Evaluation system for randomized controlled trials.

RESULTS

Fifteen studies met our search criteria (524 patients). Of the studies, 12 were graded Level IV evidence; 2, Level III; and 1, Level II. Six different RIC technique descriptions were reported, with 2 studies not defining the details of the procedure. The most common method of RIC was arthroscopic plication of the superior glenohumeral ligament to the middle glenohumeral ligament (8 of 15 studies). The most commonly used patient-reported outcome measure was the Rowe score, with all studies reporting a minimum postoperative score of 80 points. The rate of return to preinjury level of sport ranged from 22% to 100%, and the postoperative redislocation rate ranged from 0% to 16%.

CONCLUSIONS

The indications for RIC were poorly reported, and the surgical techniques were inconsistent. Although most studies reported positive clinical results, the heterogeneity of outcome measures limited our ability to make definitive statements about which types of rotator interval capsular closure are warranted for select subgroups undergoing arthroscopic shoulder stabilization.

LEVEL OF EVIDENCE

Level IV, systematic review of Level II through IV studies.

Posterior Shoulder Instability

Posterior shoulder instability is a relatively uncommon condition, occurring in ∼10% of those with shoulder instability. Because of the rarity of the condition and the lack of knowledge in treatment, it is often misdiagnosed or patients experience a delay in diagnosis. Posterior instability typically affects athletes participating in contact or overhead sports and is usually the result of repetitive microtrauma or blunt force with the shoulder in the provocative position of flexion, adduction, and internal rotation, leading to recurrent subluxation events. Acute traumatic posterior dislocations are rare injuries with an incidence rate of 1.1 per 100,000 person years. This rate is ∼20 times lower than that of anterior shoulder dislocations. Risk factors for recurrent instability are: (1) age below 40 at time of first instability; (2) dislocation during a seizure; (3) a large reverse Hill-Sachs lesion; and (4) glenoid retroversion. A firm understanding of the pathoanatomy, along with pertinent clinical and diagnostic modalities is required to accurately diagnosis and manage this condition.

The Rotator Interval - A Link Between Anatomy and Ultrasound

Shoulder pathologies of the rotator cuff of the shoulder are common in clinical practice. The focus of this pictorial essay is to discuss the anatomical details of the rotator interval of the shoulder, correlate the anatomy with normal ultrasound images and present selected pathologies. We focus on the imaging of the rotator interval that is actually the anterosuperior aspect of the glenohumeral joint capsule that is reinforced externally by the coracohumeral ligament, internally by the superior glenohumeral ligament and capsular fibers which blend together and insert medially and laterally to the bicipital groove. In this article we demonstrate the capability of high-resolution musculoskeletal ultrasound to visualize the detailed anatomy of the rotator interval. MSUS has a higher spatial resolution than other imaging techniques and the ability to examine these structures dynamically and to utilize the probe for precise anatomic localization of the patient's pain by sono-palpation.

All-Arthroscopic Modified Rotator Interval Slide for Massive Anterosuperior Cuff Tears Using the Subdeltoid Space: Surgical Technique and Early Results

BACKGROUND

Traditional intra-articular arthroscopic repair techniques for massive anterosuperior rotator cuff tears are technically demanding and necessitate sacrifice of the rotator interval to enable visualization. An interval slide allows mobilization through release of the medial aspect of the rotator interval, while leaving the lateral, bridging fibers intact.

QUESTIONS/PURPOSES

The purpose of this study was to report a novel, arthroscopic, open-equivalent technique using the subdeltoid space to address these tears along with early clinical results.

METHODS

A retrospective review of prospectively collected data identified 11 consecutive arthroscopic massive anterosuperior rotator cuff repairs with a concomitant biceps tenodesis performed by the senior surgeon using a uniform technique. Outcome measures included range of motion, visual analog scale for pain, rotator cuff strength, American Shoulder and Elbow Surgeons (ASES) outcome scale, and Short Form-12 (SF-12).

RESULTS

Average length of follow-up was 22.2 months (range 12.5-30.0 months). Visual analog scale (VAS) pain scores, ASES, and SF-12 all demonstrated significant improvement from pre-op to final follow-up from 6.2 to 0.9 (p < 0.05), 27.4 to 82.8 (p < 0.05), and 26.6 to 45.5 (p < 0.05) respectively. Average forward flexion improved from 145° to 160° (p < 0.05). Seven of the nine patients with a positive preoperative belly press had a negative test at final follow-up. Nine of the 10 patients with a positive lift off test demonstrated a negative test on final follow-up. Ninety-one percent reported they were satisfied with their outcome.

CONCLUSIONS

The described modified all-arthroscopic subdeltoid approach for anterosuperior cuff repairs enabled an open-equivalent interval slide technique that preserved the bridging lateral fibers of the rotator interval and demonstrated promising early-term clinical results.

The Rotator Interval of the Shoulder: Implications in the Treatment of Shoulder Instability

Biomechanical studies have shown that repair or plication of rotator interval (RI) ligamentous and capsular structures decreases glenohumeral joint laxity in various directions. Clinical outcomes studies have reported successful outcomes after repair or plication of these structures in patients undergoing shoulder stabilization procedures. Recent studies describing arthroscopic techniques to address these structures have intensified the debate over the potential benefit of these procedures as well as highlighted the differences between open and arthroscopic RI procedures. The purposes of this study were to review the structures of the RI and their contribution to shoulder instability, to discuss the biomechanical and clinical effects of repair or plication of rotator interval structures, and to describe the various surgical techniques used for these procedures and outcomes.

The anatomy of the coracohumeral ligament and its relation to the subscapularis muscle

BACKGROUND

Only a few reports describe the extension of the coracohumeral ligament to the subscapularis muscle. The purposes of this study were to histo-anatomically examine the structure between the ligament and subscapularis and to discuss the function of the ligament.

METHODS

Nineteen intact embalmed shoulders were used. In 9 shoulders, the expansion of the ligament was anatomically observed, and in 6 of these 9, the muscular tissue of the supraspinatus and subscapularis was removed to carefully examine the attachments to the tendons of these muscles. Five shoulders were frozen and sagittally sectioned into 3-mm-thick slices. After observation, histologic analysis was performed on 3 of these shoulders. In the remaining 5 shoulders, the coracoid process was harvested to investigate the ligament origin.

RESULTS

The coracohumeral ligament originated from the horizontal limb and base of the coracoid process and enveloped the cranial part of the subscapularis muscle. The superficial layer of the ligament covered a broad area of the anterior surface of the muscle. Laterally, it protruded between the long head of the biceps tendon and subscapularis and attached to the tendinous floor, which extended from the subscapularis insertion. Histologically, the ligament consisted of irregular and sparse fibers abundant in type III collagen.

CONCLUSION

The coracohumeral ligament envelops the whole subscapularis muscle and insertion and seems to function as a kind of holder for the subscapularis and supraspinatus muscles. The ligament is composed of irregular and sparse fibers and contains relatively rich type III collagen, which would suggest flexibility.

Single-row, double-row, and transosseous equivalent techniques for isolated supraspinatus tendon tears with minimal atrophy: A retrospective comparative outcome and radiographic analysis at minimum 2-year followup

Purpose:

The purpose of this study was to measure and compare the subjective, objective, and radiographic healing outcomes of single-row (SR), double-row (DR), and transosseous equivalent (TOE) suture techniques for arthroscopic rotator cuff repair.

Materials and Methods:

A retrospective comparative analysis of arthroscopic rotator cuff repairs by one surgeon from 2004 to 2010 at minimum 2-year followup was performed. Cohorts were matched for age, sex, and tear size. Subjective outcome variables included ASES, Constant, SST, UCLA, and SF-12 scores. Objective outcome variables included strength, active range of motion (ROM). Radiographic healing was assessed by magnetic resonance imaging (MRI). Statistical analysis was performed using analysis of variance (ANOVA), Mann — Whitney and Kruskal — Wallis tests with significance, and the Fisher exact probability test <0.05.

Results:

Sixty-three patients completed the study requirements (20 SR, 21 DR, 22 TOE). There was a clinically and statistically significant improvement in outcomes with all repair techniques (ASES mean improvement P = <0.0001). The mean final ASES scores were: SR 83; (SD 21.4); DR 87 (SD 18.2); TOE 87 (SD 13.2); (P = 0.73). There was a statistically significant improvement in strength for each repair technique (P < 0.001). There was no significant difference between techniques across all secondary outcome assessments: ASES improvement, Constant, SST, UCLA, SF-12, ROM, Strength, and MRI re-tear rates. There was a decrease in re-tear rates from single row (22%) to double-row (18%) to transosseous equivalent (11%); however, this difference was not statistically significant (P = 0.6).

Conclusions:

Compared to preoperatively, arthroscopic rotator cuff repair, using SR, DR, or TOE techniques, yielded a clinically and statistically significant improvement in subjective and objective outcomes at a minimum 2-year follow-up.

Level of Evidence:

Therapeutic level 3.

Variation of the subscapularis tendon at the fetal glenohumeral joint

We examined the topohistology of the subscapularis tendon at the glenohumeral joint in 10 mid-term (15-16 weeks of gestation) and 10 late-stage (27-32 weeks) human fetuses. At both stages, there were two patterns of terminal course of the subscapularis tendon: 1) the tendon was tightly attached to the medial part of the joint capsule and extended anterosuperiorly along the capsule to the lesser tubercle (7/10 mid-term fetuses; 5/10 late-stage fetuses); 2) the tendon passed superiorly through the joint cavity for a long distance in combination with the subcoracoid bursa opening widely to the joint cavity (3/10 mid-term fetuses; 5/10 late-stage fetuses). The lower glenoid labrum tended to be well developed in the former pattern because the subscapularis tendon did not interfere with the superior extension of the labrum. With only one exception (late stage), the capsule-attaching tendon was seen in fetuses in which the coracoid process was located on the superior side of the lesser tubercle, whereas the intra-articular tendon accompanied the coracoid process at the same supero-inferior level of the tubercle. Thus, the topographical relationship between the coracoid process and lesser tubercle in fetuses seemed to determine the courses of the subscapularis tendon at the glenohumeral joint. The present variation in the subscapularis tendon was likely connected with the adult morphologies of the middle and inferior glenohumeral ligaments or folds, whose variations are well known.

Anatomy and histology of the transverse humeral ligament

The classic literature describes the transverse humeral ligament (THL) as a distinct anatomic structure with a role in biceps tendon stability; however, recent literature suggests that it is not a distinct anatomic structure. The purpose of this study was to evaluate the gross and microscopic anatomy of the THL, including a specific investigation of the histology of this ligament. Thirty frozen, embalmed cadaveric specimens were dissected to determine the gross anatomy of the THL. Seven specimens were evaluated histologically for the presence of mechanoreceptors and free nerve endings. Two tissue layers were identified in the area described as the THL. In the deep layer, fibers of the subscapularis tendon were found to span the bicipital groove with contributions from the coracohumeral ligament and the supraspinatus tendon. Superficial to this layer was a fibrous fascial covering consisting of distinct bands of tissue. Neurohistology staining revealed the presence of free nerve endings but no mechanoreceptors. This study's findings demonstrate that the THL is a distinct structure continuous with the rotator cuff tendons and the coracohumeral ligament. The finding of free nerve endings in the THL suggests a potential role as a shoulder pain generator.

Posterior shoulder instability in the contact athlete

Historically, posterior shoulder instability has been a challenging problem for contact athletes and orthopedic surgeons alike. A complete understanding of the normal shoulder anatomy and biomechanics and the pathoanatomy responsible for the instability is necessary for a successful clinical outcome. In addition, the surgeon must be familiar with the diagnostic imaging and physical examination maneuvers required for the correct diagnosis without missing any other concurrent abnormalities. This understanding will allow orthopedists to plan and execute the appropriate management, whether this may involve conservative or surgical intervention. The goal should always be to correct the abnormality and have the patient return to play with full strength and no recurrent instability.

Variability of the capsular anatomy in the rotator interval region of the shoulder

PURPOSE

Anterior shoulder anatomy is as complex and variable as its descriptive terminology. A detailed understanding of normal anatomic variability is critical to accurate performance, description, and evaluation of the procedures involving the rotator interval. We aimed to define, arthroscopically, the anatomic variability in the rotator interval region of the shoulder and to compare these results to the findings of previous cadaveric studies.

METHODS

The rotator interval anatomy of 104 consecutive patients was classified according to the system of DePalma. Anatomic variability was evaluated and compared with findings of previous authors.

RESULTS

Shoulders were classified as follows: 59% type 1 (rotator interval capsular opening [RICO] superolateral to the MGHL); 1% type 2 (RICO inferomedial to the middle glenohumeral ligament [MGHL]); 22% type 3 (2 RICOs: 1 above and 1 below the MGHL); 9% type 4 (large RICO, no MGHL); 0% type 5 (the MGHL is manifested as 2 small RICOs); 7% Type 6 (no RICO); and 3% distinct Buford complex. We found a larger percentage of type 1 shoulders and a lower percentage of type 3 shoulders relative to prior open cadaveric dissections. No difference in the distribution of DePalma types was noted based surgical indication.

CONCLUSIONS

The anatomy of the rotator interval as viewed arthroscopically is complex and variable. While DePalma types 1 and 3 are most commonly encountered, other anatomic variants are frequent and should be considered when assessing and manipulating structures in region of the rotator interval and anterior shoulder.

The Anatomic Variability of the ‘Rotator Interval Capsule’: A Comparison of Arthroscopic and Open Investigations

Introduction:

Variably present rotator interval capsular openings (RICOs) complicate anterior shoulder capsular anatomy. Open and arthroscopic approaches may lead to differences in the appearance and size of RICOs. The purposes of this study are to: (1) Confirm that RICOs viewed from inside and outside the joint are the same structures, and (2) compare the size of RICOs when approached in an open manner vs arthroscopically.

Materials and methods

Twelve fresh cadaveric shoulders were randomized to two different approaches in order to identify and mark RICOs. In the first group, the superior glenohumeral ligament (SGHL) and middle glenohumeral ligament (MGHL) were marked arthroscopically. Sutures were placed in these structures in an open fashion. Repeat arthroscopy was then performed to determine whether the sutures penetrated the marked SGHL and MGHL. In the second group, these steps were reversed and arthroscopically placed sutures were evaluated in an open manner. Dimensions of the RICOs were measured both arthroscopically and open in each shoulder.

Results

All specimens had a RICO visualized both arthroscopically and open. Five of 12 specimens had an additional second RICO. RICO size measurements were similar for the arthroscopic and open techniques. Sutures placed via both the arthroscopic and open technique were noted to penetrate the marked structures in all cases. In addition, sutures placed through the SGHL while viewing arthroscopically always captured the coracohumeral ligament (CHL). Sutures placed through the SGHL with an open technique never engaged the CHL.

Conclusion

The capsular openings in the rotator interval were confirmed to be the same structures when observed arthroscopically and through an open approach.

Svoboda SJ, Taylor DC, Magnussen RA. The Anatomic Variability of the ‘Rotator Interval Capsule’: A Comparison of Arthroscopic and Open Investigations. The Duke Orthop J 2013;3(1):54-60.

Evaluation and management of posterior shoulder instability

CONTEXT

Posterior shoulder instability is a commonly misdiagnosed disorder in many competitive athletes.

TYPE OF STUDY

Clinical review.

EVIDENCE ACQUISITION

Relevant studies on posterior shoulder instability from 1950 to 2010 in PubMed and Cochrane databases were reviewed.

RESULTS

A total of 107 studies were reviewed.

CONCLUSION

Patients who have undergone at least 6 months of physical therapy and still experience instability symptoms should be considered for surgical stabilization directed at their underlying pathology.

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.

Arthroscopic management of posterior instability

In comparison with anterior shoulder instability, posterior instability is uncommon, occurring in 2% to 10% of cases, and covering a wide clinical spectrum ranging from locked posterior dislocation to the often subclinical recurrent posterior subluxation (RPS). With increased clinical awareness, imaging advances such as magnetic resonance arthrography, and the development of specific provocative physical examination tests, the identification of RPS in the athletic population is improving. This article describes the anatomic-based arthroscopic approach to treatment of RPS, which allows for enhanced identification and repair of intra-articular pathology including posterior capsular laxity, complete or incomplete detachment of the posterior capsulolabral complex, and inferior capsular tears. While postoperative results are generally good to excellent after stabilization for RPS, there is room for improvement.

Primary total shoulder arthroplasty performed entirely thru the rotator interval: technique and minimum two-year outcomes

BACKGROUND

Total shoulder replacement (TSR) is an effective treatment of shoulder arthritis. However, subscapularis insufficiency after TSR remains a significant cause of poor outcomes after shoulder arthroplasty. We describe a novel technique for performing a TSR entirely through the rotator interval (RI) without tenotomy of the subscapularis or supraspinatus tendons and without dislocating the shoulder using the superior approach.

MATERIAL AND METHODS

We prospectively followed up 22 patients who underwent this procedure. Subjective patient satisfaction, Constant, Simple Shoulder Test (SST) scores, and range of motion (ROM) were evaluated preoperatively and postoperatively at a mean follow-up of 29 months. Radiographic findings are also presented.

RESULTS

Subjective patient satisfaction results were good in 5 of 17 patients and excellent in 12. Patients also had significant increases in Constant, visual analog scale, SST, and ROM scores. One patient was excluded due to a traumatic periprosthetic fracture (fall), 3 patients refused to return for follow-up, and 1 patient was lost to follow-up. Postoperative results included nonanatomic humeral head osteotomies in 6, residual inferior humeral neck osteophytes in 8, and the humeral head prosthesis was undersized in 5.

CONCLUSIONS

The patients had favorable clinical outcomes. This technique for TSR demonstrates that in the postoperative period, patients can immediately partake in unrestricted physical therapy. This study reports the clinical outcomes of this technique for TSR with a minimum of 2 years of follow-up.

LEVEL OF EVIDENCE

Level 4; Case series, treatment study.

Treating the athlete with anterior shoulder instability

Acute traumatic anterior shoulder dislocation is a relatively common occurrence in the athletic population. Although the overall incidence of traumatic shoulder instability in the general population is only 1.7%, the incidence in a high physical-demand population is two-fold greater. Instability often becomes a recurrent pattern and jeopardizes athletic performance and participation. A thorough assessment and discussion with the patient with respect to treatment decision-making are critical in the management of anterior shoulder instability.

Arthroscopic management of posterior shoulder instability: diagnosis, indications, and technique

With increased understanding of the different patterns of posterior shoulder instability, diagnostic acumen and successful treatment algorithms have evolved. Improvements in imaging and advancements in arthroscopic surgical techniques have facilitated this progress. In athletic populations, recurrent posterior subluxations (RPSs) are far more common than recurrent or locked posterior dislocations. Conservative and operative management of posterior instability is individualized to meet the demands of its diverse patient population, ranging from post-traumatic instability in contact athletes to RPSs in overhead athletes.

Identifying the cellular basis for reimplantation failure in repair of the rotator cuff

We examined cultured osteoblasts derived from paired samples from the greater tuberosity and acromion from eight patients with large chronic tears of the rotator cuff. We found that osteoblasts from the tuberosity had no apparent response to mechanical stimulation, whereas those derived from the acromion showed an increase in alkaline phosphatase activity and nitric oxide release which is normally a response of bone cells to mechanical strain. By contrast, we found that cells from both regions were able to respond to dexamethasone, a well-established promoter of osteoblastic differentiation, with the expected increase in alkaline phosphatase activity. Our findings indicate that the failure of repair of the rotator cuff may be due, at least in part, to a compromised capacity for mechanoadaptation within the greater tuberosity. It remains to be seen whether this apparent decrease in the sensitivity of bone cells to mechanical stimulation is the specific consequence of the reduced load-bearing history of the greater tuberosity in these patients.

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.

[The rotator interval: hidden lesions?]

The rotator interval corresponds to a defined triangular shaped anatomical region at the anterosuperior portion of the shoulder where specific pathological processes may occur. First, the morphological and functional anatomy of the region will be reviewed. Then, the role of different imaging modalities will be described along with pathological imaging features. Normal structures of the rotator interval may be imaged with modern techniques, including MR and CT arthrography. On the other hand, clinical evaluation of rotator interval pathology remains difficult; and no consensus exists concerning their management. Imaging characterization of rotator interval pathology could be a key factor for pre-therapeutic work-up.

The addition of rotator interval closure after arthroscopic repair of either anterior or posterior shoulder instability: effect on glenohumeral translation and range of motion

BACKGROUND

Although the use of rotator interval closure is frequently advocated as a useful supplement to shoulder instability repairs, the addition of a rotator interval closure after arthroscopic instability repair has not been fully investigated.

PURPOSE

The objective of this study was to investigate whether a rotator interval closure improves glenohumeral stability in an anterior and posterior instability shoulder model.

STUDY DESIGN

Controlled laboratory study.

METHODS

Fourteen fresh-frozen cadaveric shoulder specimens were dissected free of soft tissues, leaving the rotator cuff intact with simulated cuff loading. All specimens were mounted in a custom testing apparatus using infrared sensors to document glenohumeral translation and rotation. The specimens were then tested for stability in the following order: vented/subluxated state, after arthroscopic anterior (Group 1; 7 specimens) or posterior (Group 2; 7 specimens) instability repair with suture anchors, and then after rotator interval closure. For each of the 3 testing conditions, the following were measured: (1) external and internal rotation at neutral, (2) external and internal rotation at 90 degrees of abduction, (3) posterior and anterior translation at neutral rotation (15 N and 25 N), (4) anterior translation at 90 degrees of abduction and external rotation (Group 1; 15 N and 25 N), (5) posterior translation at 90 degrees of flexion and internal rotation (Group 2; 15 N and 25 N), and (6) sulcus testing in neutral (7.5 N).

RESULTS

Posterior stability was only improved after anchor capsulolabral repair (8.0 to 5.0 mm; P = .017, 25 N), but there was no improvement after rotator interval closure (5.0 to 4.6 mm; P = .453). However, anterior stability was improved after capsulolabral repair (8.6 to 4.0 mm; P = .016, 25 N) and also improved further by rotator interval closure (4.0 to 2.4 mm; P = .007). The mean loss of external rotation was significantly increased by the addition of the rotator interval closure in both neutral and abducted glenohumeral positions, with a mean external rotation loss of 28 degrees in neutral (P = .013). The addition of a rotator interval closure did not improve sulcus stability (P = .4).

CONCLUSION

The addition of an arthroscopic rotator interval closure after posterior capsulolabral repair did not improve posterior stability; however, anterior stability was improved further after a rotator interval closure. Inferior stability was not improved. Arthroscopic rotator interval closure significantly decreased external rotation at both neutral and abducted arm positions.

CLINICAL RELEVANCE

Arthroscopic closure may be beneficial in certain cases of anterior shoulder instability; however, posterior instability was not improved. Predictable losses of external rotation after rotator interval closure are of concern.

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.

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.

MRI of the rotator interval of the shoulder

The rotator interval of the shoulder joint is located between the distal edges of the supraspinatus and subscapularis tendons and contains the insertions of the coracohumeral and superior glenohumeral ligaments. These structures form a complex pulley system that stabilizes the long head of the biceps tendon as it enters the bicipital groove of the humeral head. The rotator interval is the site of a variety of pathological processes including biceps tendon lesions, adhesive capsulitis and anterosuperior internal impingement. This article describes the anatomy, function and pathology of the rotator interval using magnetic resonance imaging (MRI).

Recurrent posterior shoulder instability

Recurrent posterior shoulder instability is an uncommon condition. It is often unrecognized, leading to incorrect diagnoses, delays in diagnosis, and even missed diagnoses. Posterior instability encompasses a wide spectrum of pathology, ranging from unidirectional posterior subluxation to multidirectional instability to locked posterior dislocations. Nonsurgical treatment of posterior shoulder instability is successful in most cases; however, surgical intervention is indicated when conservative treatment fails. For optimal results, the surgeon must accurately define the pattern of instability and address all soft-tissue and bony injuries present at the time of surgery. Arthroscopic treatment of posterior shoulder instability has increased application, and a variety of techniques has been described to manage posterior glenohumeral instability related to posterior capsulolabral injury.

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.

Simplified arthroscopic rotator interval capsule closure: an alternative technique

The anatomy of the "coracoid eclipse" of the rotator cuff, the rotator interval, has been studied extensively. Its importance in shoulder stability with respect to inferior and posterior translation has been described. Historically, open repairs for instability indirectly addressed interval lesions and closure based simply on the definition of the deltopectoral approach with its subscapularis advancement and capsular shift in a "pants-over-vest" manner. With results of arthroscopic repairs of glenohumeral instability approaching those of open procedures, the importance of simplification without sacrificing outcome has become a forefront in arthroscopic shoulder surgery. We present an alternative technique for interval closure by means of a 3/32-inch smooth Steinmann pin modified at its proximal and distal ends. A standard 3-portal technique consisting of the anterior superior portal, anterior mid-glenoid portal, and the posterior superior portal is used. The technique does not require the use of a suture shuttle nor does it require the placement of the arthroscope in the subacromial space for suture tying. A Tennessee slider knot is tied intra-articularly, thus allowing for tension modification before definitive alternate locking half-hitch placement. Intra-articular knot tying also allows for added security because suture slack is eliminated, thus avoiding air knots.

Rotator interval closure after arthroscopic capsulolabral repair: a technical variation

Rotator interval tear is one of the lesions identified in patients with glenohumeral instability. We present our technique for arthroscopic interval capsule repair. After having performed Bankart reconstruction, we pull the anterosuperior cannula back some millimeters and introduce a Penetrator suture retriever forceps (Arthrex, Naples, FL) through the upper interval capsule into the joint. Then we also remove some millimeters of the anterior cannula and introduce a suture passer (Spectrum; Linvatec, Largo, FL) loaded with a monofilament suture through the lower interval capsule. The suture is pushed into the joint and, using the Penetrator suture retriever forceps, we retrieve it out of the joint. This suture is replaced if desired by a permanent braided suture. Next, a suture passer (Arthrex) advances the end of the suture from the anterosuperior portal into the joint. The suture is retrieved out of the joint from the anterior cannula with a crochet hook. We tie the suture down the anterior cannula to close the anterior capsule. Because we use cannulas, we can use a sliding knot. The degree of tightening can be observed directly under arthroscopic view but the knot is outside of the capsule. We believe that this method is easy, effective, and reproducible.

Traumatic rupture of the coracoacromial ligament

This is a case report of an arthroscopically diagnosed injury to the coracoacromial ligament at the undersurface of the acromion. To our knowledge, this has not been previously described. Traumatic avulsion of this ligament may represent a source of subacromial impingement that has not been recognized.

MR arthrography of rotator interval, long head of the biceps brachii, and biceps pulley of the shoulder

The rotator interval and the long head of the biceps brachii tendon are anatomically closely associated structures believed to confer stability to the shoulder joint. Abnormalities of the rotator interval may be acquired or congenital and are associated with instability of the long head of the biceps brachii tendon. Clinical and arthroscopic diagnoses of rotator interval abnormalities and subtle instability patterns of the long head of the biceps brachii tendon are difficult. Magnetic resonance arthrography, owing to its superior depiction of ligaments with distention of the joint capsule, may be the procedure of choice, barring open surgery, for help in diagnosis of these conditions.