An analysis of capsular area in patients with anterior, posterior, and multidirectional shoulder instability

Imaging modalities for atraumatic shoulder hypermobility: a scoping review

BACKGROUND

Objective measures from imaging studies have the potential to assist in timely diagnosis of atraumatic shoulder hypermobility to better guide management. The aim of this scoping review is to examine imaging modalities and techniques used to characterize atraumatic shoulder hypermobility.

METHODS

MEDLINE, EMBASE, SPORTDiscus, Cochrane Library, and Web of Science were searched up to May 2024 for any primary study investigating imaging findings seen in atraumatic shoulder hypermobility. Patients with unilateral instability were excluded given its frequent association with traumatic origin.

RESULTS

Eighteen observational studies met inclusion criteria. Results were divided into outcomes relating to capsular redundancy, glenohumeral anatomy, and muscle activation. Five studies using magnetic resonance arthrography (MRA) demonstrated statistically significant increases in capsular cross-sectional area (CSA), while a significant superior capsular elongation was reported by two studies in patients with multidirectional instability (MDI). Labrocapsular distance, glenocapsular ratio, and the presence of a combined sail and triangle sign on MRA were highly sensitive and specific parameters for identifying MDI. There were inconsistent findings for alterations of glenohumeral anatomy. Ultrasound assessments of acromiohumeral distance (AHD) were significantly increased in patients with MDI, but not in shoulders with hypermobility alone. Similarly, muscle activity measured by electromyography or glenohumeral translations differed significantly in patients with MDI, but not in those with hypermobility alone.

CONCLUSION

Radiographic markers of capsular redundancy (e.g., CSA, labrocapsular distance, glenocapsular ratio), AHD, and muscular activity are useful in the diagnosis of MDI. However, there are no definitive imaging markers for diagnosing atraumatic shoulder hypermobility without MDI.

Glenohumeral Joint Volume Measurement in Patients with Shoulder Instability: A 3D Volumetric Magnetic Resonance Arthrographic Study

Background and Objectives: This study aimed to compare capsular volume in patients with shoulder instability to that in control subjects without instability using magnetic resonance (MR) arthrography. The objective was to develop a reliable screening method with which to assess shoulder volume. Materials and Methods: In 21 patients with atraumatic shoulder instability and 21 controls, thin-slice 3D volumetric MR arthrography sequences were obtained. MR arthrography images were uploaded to 3D reconstruction, and 3D images were generated. From the 3D reconstructed images, volumetric measurements of rotator interval (RI), anterior and posterior capsular (AC, PC) recesses, biceps tendon sheath (BS), axillary recess (AR), and total glenohumeral joint (TGJ) were performed. Individuals with any extra-articular contrast leakage were also recorded. Results: A retrospective study analyzed a patient group of 21 individuals with shoulder instability (mean age 29.52 ± 12.83 years) and a control group of 21 individuals without instability (mean age 35.71 ± 12.77 years). No statistically significant differences were identified between the groups with regard to age, gender, or side distribution. The mean total joint volume was significantly higher in the instability group (29.85 ± 6.40 cm3) compared to the control group (23.15 ± 3.48 cm3, p = 0.0001). Additionally, the mean volumes of the RI, AC, PC, BS, and AR were all significantly greater in the patient group compared to the control group. Conclusions: 3D volumetric MR arthrographic measurements of the shoulder joint capacity can provide valuable insights for clinical follow-up and guide surgical treatment decisions in cases of atraumatic shoulder instability.

Current Concepts on the Management of Shoulder Instability in Throwing Athletes

PURPOSE OF REVIEW

The management of shoulder instability in throwing athletes remains a challenge given the delicate balance between physiologic shoulder laxity facilitating performance and the inherent need for shoulder stability. This review will discuss the evaluation and management of a throwing athlete with suspected instability with a focus on recent findings and developments.

RECENT FINDINGS

The vast majority of throwing athletes with shoulder instability experience subtle microinstability as a result of repetitive microtrauma rather than episodes of gross instability. These athletes may present with arm pain, dead arms or reduced throwing velocity. Recent literature reinforces the fact that there is no "silver bullet" for the management of these athletes and an individualized, tailored approach to treatment is required. While initial nonoperative management remains the hallmark for treatment, the results of rehabilitation protocols are mixed, and some patients will ultimately undergo surgical stabilization. In these cases, it is imperative that the surgeon be judicious with the extent of surgical stabilization as overtightening of the glenohumeral joint is possible, which can adversely affect athlete performance. Managing shoulder instability in throwing athletes requires a thorough understanding of its physiologic and biomechanical underpinnings. Inconsistent results seen with surgical stabilization has led to a focus on nonoperative management for these athletes with surgery reserved for cases that fail to improve non-surgically. Overall, more high quality studies into the management of this challenging condition are warranted.

Evaluation and Management of Glenohumeral Instability in Adolescent Patients: An Expert Consensus Statement

Background

Management of glenohumeral instability in the adolescent population can be both challenging and controversial. There are no current guidelines for optimal management of glenohumeral instability in this population (unidirectional or multidirectional), and the cutoff ages for transition to adult treatment are not known.

Purpose

To develop consensus-based guidelines for the management of glenohumeral instability in adolescents.

Study Design

Consensus statement.

Methods

A 26-question, multiple-choice survey was developed after 2 rounds of iterations and was submitted to the orthopaedic surgeons of the Pediatric Research in Sports Medicine (PRiSM) Society. The survey comprised 3 sections-demographics, practice setting, and decision-making-and included cutoff ages and management in 5 specific case scenarios. Consensus-based guidelines were generated with 66% response agreement. An indication score was then applied to each response related to more aggressive management to determine if variables related to consensus (or lack thereof) could be identified.

Results

A total of 54 responses were returned. Of the respondents, 59% were from academic practice, 84% were pediatric orthopaedic fellowship trained, and 46% performed >25 shoulder instability cases per year. In the setting of first-time anterior shoulder dislocation, nonoperative treatment was preferred for boys aged <14 years and girls aged <13 years. Besides age, proximal humerus physeal status, injury mechanism, sport, and presence of bony injury affected treatment selection. The presence of a Bankart lesion was an indication for stabilization in first-time dislocations for contact athletes with a closing or closed physis, but not in patients with an open physis or noncontact injury mechanisms. For recurrent anterior shoulder dislocation, stabilization was preferred irrespective of physis status. Initial nonoperative treatment was preferred for multidirectional instability.

Conclusion

In the setting of first-time anterior shoulder dislocation in patients with open physes, nonoperative treatment was preferred for boys <14 years and girls <13 years. Future multicenter prospective studies focusing on outcomes would help to validate current practice patterns, especially in scenarios for which no consensus was reached.

There is high variability in quantitative measurement techniques in glenohumeral capsular measurements for shoulder instability: A systematic review

PURPOSE

Instability of the glenohumeral joint remains a complex clinical issue with high rates of surgical failure and significant morbidity. Advances in specific radiologic measurements involving the glenoid and the humerus have provided insight into glenohumeral pathology, which can be corrected surgically towards improving patient outcomes. The contributions of capsular pathology to ongoing instability remain unclear. The purpose of this study is to provide a systematic review of existing glenohumeral capsular measurement techniques published in the last 15 years.

METHODS

A systematic review of multiple databases was performed following PRISMA guidelines for all primary research articles between 2008 and 2023 with quantitative measurements of the glenohumeral capsule in patients with instability, including anterior, posterior and multi-directional instability.

RESULTS

There were a total of 14 articles meeting the inclusion criteria. High variability in measurement methodology across studies was observed, including variable amounts of intra-articular contrast, heterogeneity among magnetic resonance sequence acquisitions, differences in measurements performed and the specific approach taken to compute each measurement.

CONCLUSION

There is a need for standardization of methods in the measurement of glenohumeral capsular pathology in the setting of glenohumeral instability to allow for cross-study analysis.

LEVEL OF EVIDENCE

Level III.

Arthroscopic Labral Repair and Pancapsular Shift With Knotless All-Suture Anchors in the Setting of Multidirectional Instability of the Shoulder

In the management of multidirectional type of shoulder instability (MDI), arthroscopic surgical stabilization is a preferred treatment option after failed conservative therapy regimens because of the ability to easily access all aspects of the capsule with one surgical procedure. As arthroscopic techniques have evolved, factors critical to postoperative success have been elucidated. Currently, optimal arthroscopic treatment of MDI involves circumferentially restoring labral integrity, a tailored, patient-specific surgical reduction of capsular volume, and adequately managing potential lesions of the biceps anchor. The purpose of this article and accompanying video is to present our technique for arthroscopic circumferential labral repair and pancapsular shift using knotless all-suture anchors in the setting of MDI with a concurrent type II SLAP lesion.

Posterior Shoulder Instability in Tennis Players: Aetiology, Classification, Assessment and Management

Background

Micro-traumatic posterior shoulder instability (PSI) is an often missed and misdiagnosed pathology presenting in tennis players. The aetiology of micro-traumatic PSI in tennis players is multifactorial, including congenital factors, loss of strength and motor control, and sport-specific repetitive microtrauma. Repetitive forces placed on the dominant shoulder, particularly combinations of flexion, horizontal adduction, and internal rotation contribute to the microtrauma. These positions are characteristic for kick serves, backhand volleys, and the follow-through phase of forehands and serves. The aim of this clinical commentary is to present an overview of the aetiology, classification, clinical presentation, and treatment of micro-traumatic PSI, with a particular focus on tennis players.

Level of Evidence

5.

Comprehensive Review of Multidirectional Instability of the Shoulder

Multidirectional instability of the shoulder can result from underlying atraumatic laxity, from repetitive microtrauma, or from a traumatic injury and often occurs in association with generalized ligamentous laxity or underlying connective tissue disorders. It is critical to differentiate multidirectional instability from unidirectional instability with or without generalized laxity to maximize treatment success. Although rehabilitation is still considered the primary treatment method for this condition, surgical treatment in the form of open inferior capsular shift or arthroscopic pancapsulolabral plication is indicated if conservative treatment fails. Recent biomechanical and clinical research has shown that there is still room for improvement in the treatment methods offered to this specific patient cohort. Potential treatment options, such as various methods to improve cross-linking of native collagen tissue, electric muscle stimulation to retrain the abnormally functioning dynamic stabilizers of the shoulder, and alternative surgical techniques such as coracohumeral ligament reconstruction and bone-based augmentation procedures, are brought forth in this article as potential avenues to explore in the future.

Pediatric and Adolescent Shoulder Instability

PURPOSE OF REVIEW

Traumatic and atraumatic shoulder instability is common in pediatric and adolescent patients. It is well-established that young patients with anterior shoulder dislocation are at high risk of recurrent instability. This review assesses the current literature pertaining to management of both anterior instability and MDI in the pediatric and adolescent populations.

RECENT FINDINGS

Current research suggests that pediatric and adolescent patients with shoulder instability have excellent outcomes following arthroscopic Bankart repair; however, higher rates of recurrent instability requiring revision surgical management have been identified in patients with more than one dislocation episode pre-operatively, those with Hill-Sachs lesions and those under age 16. The addition of the remplissage procedure to an arthroscopic Bankart repair may be useful in preventing recurrent instability for patients with large Hill-Sachs lesions. Open procedures with bony glenoid augmentation may be indicated in patients with significant glenoid bone loss, or those who have failed primary surgical management, with promising outcomes reported following the Latarjet coracoid process transfer procedure in the adolescent population. Pediatric and adolescent patients with hyperlaxity, and those participating in swimming or gymnastics are more likely to have multidirectional instability (MDI). Non-surgical management with physical therapy is the mainstay of treatment for MDI with positive outcomes reported overall. In young patients with MDI who continue to have symptoms of instability and pain that effects daily activities or sports despite an adequate and appropriate course of rehabilitation, surgical management with capsulorrhaphy may be considered, with promising outcomes reported for both open and arthroscopic techniques. Attentive selection of timing and surgical procedure for pediatric and adolescent patients with anterior shoulder instability may help to prevent recurrent instability following shoulder stabilization. Although most pediatric and adolescent patients with MDI do well following non-surgical management alone, those that fail conservative management have good outcomes following arthroscopic or open capsulorrhaphy.

Editorial Commentary: Hyperlaxity Is a Common Factor in Failed Arthroscopic Bankart Repair

Hyperlaxity is a common factor in failed arthroscopic Bankart repair. The best treatment for patients with instability, hyperlaxity, and minimal bone loss is still controversial. Patients with hyperlaxity often have subluxations rather than frank dislocation, and concurrent traumatic structural lesions are infrequent. Conventional arthroscopic Bankart repair with or without capsular shift poses a risk of recurrence because of soft tissue insufficiency. The Latarjet is not a good procedure in patients with hyperlaxity and instability, especially an inferior component, and risks include a higher degree of postoperative osteolysis after Latarjet with an intact glenoid. The arthroscopic Trillat procedure may be used to treat this challenging patient group by repositioning the coracoid medially and downward by a partial wedge osteotomy. The coracohumeral distance and shoulder arch angle are decreased after performing the Trillat, which may reduce instability, and the Trillat procedure mimics the sling effect of the Latarjet. However, complications should be considered due to the procedure's nonanatomic nature, such as osteoarthritis, subcoracoid impingement, and loss of motion. Other options to improve inferior stability include robust rotator interval closure, coracohumeral ligament reconstruction, and posteroinferior/inferior/anteroinferior capsular shift. The addition of posteroinferior capsular shift and rotator interval closure in the medial lateral direction also benefits this vulnerable patient group.

Management of Shoulder Instability in Patients with Underlying Hyperlaxity

PURPOSE OF REVIEW

Shoulder instability in patients with underlying joint hyperlaxity can be challenging to treat. Poorly defined terminology, heterogeneous treatments, and sparse reports on clinical outcomes impair the development of best practices in this patient population. This article provides a review of the current literature regarding optimal management of patients suffering from shoulder instability with concomitant hyperlaxity of the shoulder, from isolated shoulder joint hyperlaxity to congenital hypermobility spectrum disorders (HSD).

RECENT FINDINGS

Current research shows specialized physiotherapy protocols focused on strengthening of periscapular muscles and improvement of sensorimotor control are a promising non-surgical therapeutic avenue in certain patients, which can be augmented by device-based intervention in select cases. If surgical treatment is warranted, arthroscopic techniques such as pancapsular shift or plication continue to demonstrate favorable outcomes and are currently considered the benchmark for success. The long-term success of more recent innovations such as coracoid process transfers, conjoint tendon transfers, subscapularis tendon augmentation, and capsular reconstruction remains unproven. For patients affected by connective tissue disorders, treatment success is generally less predictable, and the entire array of non-operative and operative interventions needs to be considered to achieve the best patient-specific treatment results. In the treatment of shoulder instability and concomitant hyperlaxity, specialized physiotherapy protocols augmented by device-based interventions have emerged as powerful, non-operative treatment options for select patients. Successful surgical approaches have been demonstrated to comprehensively address capsular redundancy, labral lesions, and incompetence of additional passive stabilizers in a patient-specific fashion, respective of the underlying connective tissue constitution.

Imaging Posterior Instability of the Shoulder

Posterior instability of the shoulder is much less common than anterior instability with a clinical presentation that is often less obvious, making the diagnosis more challenging and more easily missed. We describe the imaging findings of posterior instability so the radiologist can make the diagnosis and provide a detailed description, enabling the surgeon to make more informed decisions regarding management and surgery.

The Thumb Test: A Simple Physical Examination Maneuver for the Diagnosis of Symptomatic Posterior Shoulder Instability

Posterior shoulder instability is becoming increasingly recognized in young active patient populations. Diagnosing posterior instability can be challenging because patients commonly present with a complaint of pain without a history of a dislocation or subluxation event. Additionally, a posterior labral tear is not always clearly visualized on advanced imaging studies. As such, physical examination is critical to the diagnosis. We report a simple physical examination maneuver for the diagnosis of symptomatic posterior shoulder instability. The thumb test attempts to replicate a posterior bone block procedure, helping to re-establish stability and relieve pain. The examiner places his or her thumb over the posterior glenohumeral joint line while the patient actively forward elevates the affected arm overhead. Improvement in pain and stability with this maneuver is diagnostic for symptomatic posterior shoulder instability. This test augments current physical examination maneuvers to assist with correctly diagnosing posterior shoulder instability.

Magnetic resonance arthrography in patients with multidirectional instability: could inferior capsulsar width be considered the cornerstone in the diagnosis of non-traumatic shoulder instability?

OBJECTIVES

To provide quantitative anatomical parameters in patients with and without non-traumatic multidirectional instability using MR arthrography (MR-a).

MATERIALS AND METHODS

One hundred and seventy-six MR-a performed from January 2020 to March 2021 were retrospectively evaluated. Patients were divided according to the presence of clinically diagnosed multidirectional shoulder instability (MDI). Each MR-a was performed immediately after intra-articular injection of 20 ml of gadolinium using the anterior approach. The width of the axillary recess, the width of the rotator interval, and the circumference of the glenoid were measured by three independent radiologists, choosing the average value of the measurements. The difference between the mean values of each of the three parameters between the two study groups was then assessed.

RESULTS

Thirty-seven patients were included in the study (20 in the MDI group, 17 in the control group). The mean axillary recess width in the MDI group was significantly greater than in the control group (t(33) = 3.15, p = .003); rotator interval width and glenoid circumference measurements were not significantly different (t(35) = 1.75, p = .08 and t(30) = 0,51, p = .6, respectively).

CONCLUSIONS

Inferior capsular redundancy may be an important predisposing factor in MDI, while glenoid circumference is not related to MDI. The relationship between the width of the rotator interval and shoulder instability remains debated.

High Incidence of Anterior Shoulder Pain in Young Athletes Undergoing Arthroscopic Posterior Labral Repair for Posterior Shoulder Instability

Purpose

The purposes of this study were to determine the incidence of anterior shoulder pain in young athletes undergoing arthroscopic posterior labral repair for symptomatic unidirectional posterior shoulder instability and in patients with preoperative anterior shoulder pain treated without biceps tenodesis at the time of arthroscopic posterior labral repair who underwent a revision biceps tenodesis procedure at short-term follow up.

Methods

A retrospective review was performed at a single institution over a 24-month period. The study included young patients who underwent an arthroscopic posterior labral repair for symptomatic unidirectional posterior shoulder instability. The electronic medical record, magnetic resonance arthrograms, and arthroscopic images were reviewed to exclude patients with posterior labral tears with anterior labral tear or SLAP (superior labrum anterior-to-posterior) tear extension on advanced imaging and arthroscopic examination. Data collected included the presence of preoperative tenderness to palpation of the biceps tendon in the groove, the results of a preoperative Speed test, postoperative Subjective Shoulder Value, the presence of postoperative anterior shoulder pain, and the need for a secondary biceps tenodesis.

Results

We identified 65 patients who underwent arthroscopic labral repair for posterior shoulder instability. From this cohort, 26 patients with symptomatic unidirectional posterior shoulder instability underwent an arthroscopic posterior labral repair. The incidence of preoperative anterior shoulder pain with Zone 2 biceps groove tenderness and a positive Speed test was identified in 20 of 26 patients (76.9%). Of 26 patients, 5 (19%) had concomitant biceps tenodesis. The median postoperative Subjective Shoulder Value was 80 (interquartile range, 60-90) at median follow-up of 2.1 years. Of the 20 patients with preoperative anterior shoulder pain, 8 of 20 (40%) reported persistent anterior pain. One patient (4.7%) underwent a secondary biceps tenodesis.

Conclusions

There is a high incidence of anterior shoulder pain and Zone 2 biceps groove tenderness in patients undergoing isolated arthroscopic posterior labral repair for unidirectional posterior shoulder instability. At short-term follow-up, few patients required a secondary biceps tenodesis procedure; however, 30% of patients had persistent anterior shoulder pain.

Level of Evidence

Level IV, retrospective diagnostic case series.

Bankart Repair With Subscapularis Augmentation in Athletes With Shoulder Hyperlaxity

PURPOSE

The purpose of this study was to demonstrate that arthroscopic Bankart repair with associated arthroscopic subscapularis augmentation (ASA) could be a valid surgical option in the treatment of anterior shoulder instability, in collision and contact sports athletes, affected by shoulder hyperlaxity.

METHODS

In total, 591 arthroscopic Bankart repairs plus ASA were performed in 6 shoulder centers from 2009 to 2017. Inclusion criteria were the following: collision and contact sports activities, recurrent anterior instability associated with hyperlaxity and glenoid bone loss (GBL) < 15%. Exclusion criteria were GBL > 15%, voluntary instability, multidirectional instability, pre-existing osteoarthritis and throwing athletes. The minimum follow-up was 24 months. Hyperlaxity was clinically evaluated according to Neer and Coudane-Walch tests. Before surgery, all patients underwent magnetic resonance imaging and computed tomography scanning. Pico area method was used to assess the percentage of GBL. Patients were operated on by 6 surgeons, and their functional outcomes were evaluated by 2 independent observers. The Western Ontario Shoulder Instability Index (WOSI), Rowe, American Shoulder and Elbow Surgeons (ASES) scores were used to assess results.

RESULTS

Overall, 397 patients with evidence of shoulder hyperlaxity (positive sulcus sign in ER1 position and Coudane-Walch test > 85°) met all inclusion criteria. The mean WOSI score was 321; the mean Rowe score rose from 68.5 to 92.5 (P = .037), and the ASES score rose from 71.5 to 97.4 (P = .041). Seven patients (1.6%) had atraumatic redislocation, and 9 patients (2.2%) had post-traumatic redislocation. At final follow-up the mean functional deficit of external rotation was 15° with the arm in adduction (ER1 position) and 10° in abduction (ER2 position).

CONCLUSIONS

The Bankart repair plus ASA has been demonstrated to be safe and effective for restoring joint stability in patients practicing collision and contact sports or affected by chronic anterior shoulder instability associated with GBL (<15%) and hyperlaxity, without compromising external rotation.

LEVEL OF EVIDENCE

Level IV, case series.

Rehabilitation Following Posterior Shoulder Stabilization

Posterior shoulder instability has been noted in recent reports to occur at a higher prevalence than originally believed, with many cases occurring in active populations. In most cases, primary surgical treatment for posterior shoulder instability-a posterior labral repair-is indicated for those patients who have failed conservative management and demonstrate persistent functional limitations. In order to optimize surgical success and return to a prior level of function, a comprehensive and focused rehabilitation program is crucial. Currently, there is a limited amount of literature focusing on rehabilitation after surgery for posterior instability. Therefore, the purpose of this clinical commentary is to present a post-surgical rehabilitation program for patients following posterior shoulder labral repair, with recommendations based upon best medical evidence.

LEVEL OF EVIDENCE

5.

The Incidence of Posterior and Combined AP Shoulder Instability Treatment with Surgical Stabilization Is Higher in an Active Military Population than in the General Population: Findings from the US Naval Academy

BACKGROUND

Anterior instability has consistently been shown to be the most common type of glenohumeral instability. Recent studies have demonstrated a higher percentage of posterior and combined (anterior and posterior) instability than had previously been reported; however, this work has not been replicated recently in a particularly young military population, which may be representative of an especially athletic or high-demand group.

QUESTION/PURPOSE

What proportion of arthroscopic shoulder stabilization procedures are performed to address isolated anterior instability, isolated posterior instability, and combined instability in a young, military population?

METHODS

Between August 2009 and January 2020, two sports medicine fellowship-trained surgeons performed arthroscopic shoulder surgery on 543 patients at a single institution. During that time, the indication to be treated with arthroscopic stabilization surgery was symptomatic glenohumeral instability, as diagnosed by the operative surgeon, that restricted patients from carrying out their military duties. Of those, 82% (443 of 543) could be evaluated in this retrospective study, while 18% (100 of 543) were excluded due to either incomplete data or because the procedure performed was not to address instability. No patient underwent an open stabilization procedure during this period. Of the 443 patients investigated, the mean age was 22 ± 4 years, and 88% (392 of 443 patients) were men. Instability type was characterized as isolated anterior, isolated posterior, or combined (anterior and posterior) according to the physician's diagnosis as listed in the patient's clinical records and operative reports after the particular capsulolabral pathology was identified and addressed.

RESULTS

Isolated anterior instability occurred in 47% of patients (210 of 443). Isolated posterior instability happened in 18% of patients (80 of 443), while combined anteroposterior instability occurred in 35% of patients (153 of 443).

CONCLUSION

Shoulder instability is common in the military population. Although anterior instability occurred most frequently, these findings demonstrate higher proportions of posterior and combined instability than have been previously reported. Surgeons should have a heightened suspicion for posterior and combined anteroposterior labral pathology when performing arthroscopic stabilization procedures to ensure that these instability patterns are recognized and treated appropriately. The current investigation examines a unique cohort of young and active individuals who are at particularly high risk for instability and whose findings may represent a good surrogate for other active populations that a surgeon may encounter.Level of Evidence Level III; therapeutic study.

Glenoid Orientation and Profile in Atraumatic or Microtraumatic Posterior Shoulder Instability: Morphological Analysis Using Computed Tomography Arthrogram

Background:

Posterior shoulder instability (PSI) is a relatively uncommon condition that occurs in about 10% of patients with shoulder instability. PSI is usually associated with dislocations due to acute trauma and multidirectional instability, but it can also occur with or without recognizable recurrent microtrauma. The infrequency of atraumatic or microtraumatic PSI and the lack of a full understanding of the pathoanatomy and the knowledge of management can lead to misdiagnosis or delayed diagnosis.

Purpose:

To evaluate the morphologic factors of the glenoid that are associated with atraumatic or microtraumatic PSI.

Study Design:

Cross-sectional study; Level of evidence, 3.

Methods:

Enrolled in this study were patients who underwent arthroscopic posterior labral repair between January 2013 and March 2017 and were diagnosed with posterior glenohumeral instability by means of preoperative computed tomography arthrography (CTA) (n = 39; PSI group). These patients did not have any significant dislocation or subluxation episodes. The morphologic factors of the glenoid as revealed using CTA were compared with the CTA images from a sex-matched control group (n = 117) of patients without PSI who had been diagnosed with adhesive capsulitis in an outpatient clinic. The glenoid version and shape were evaluated between the 2 groups using the CTA findings, and the degree of centricity of the humeral head to the glenoid was assessed in the PSI group. Multivariate logistic regression analysis was performed to identify factors associated with PSI.

Results:

The results of the multivariate logistic regression analysis indicated no statistically significant difference between the PSI and control groups regarding glenoid version or a flat-shaped glenoid. However, statistically significant between-group differences were found regarding convex glenoid shape, with an odds ratio of 5.39 (95% CI, 1.31-23.35; P = .0207). The proportion of eccentricity was significantly higher in the PSI group (21/39; 54%) versus the control group (47/117; 40%) (P = .031).

Conclusion:

The presence of convex glenoid shape was significantly associated with atraumatic or microtraumatic PSI. Humeral head eccentricity accounted for a high percentage of convex glenoid shape. However, there was no significant correlation between PSI and glenoid retroversion.

Similar scapular morphology in patients with dynamic and static posterior shoulder instability

Background

There is evidence that specific variants of scapular morphology are associated with dynamic and static posterior shoulder instability. To this date, observations regarding glenoid and/or acromial variants were analyzed independently, with two-dimensional imaging or without comparison with a healthy control group. Therefore, the purpose of this study was to analyze and describe the three-dimensional (3D) shape of the scapula in healthy and in shoulders with static or dynamic posterior instability using 3D surface models and 3D measurement methods.

Methods

In this study, 30 patients with unidirectional posterior instability and 20 patients with static posterior humeral head subluxation (static posterior instability, Walch B1) were analyzed. Both cohorts were compared with a control group of 40 patients with stable, centered shoulders and without any clinical symptoms. 3D surface models were obtained through segmentation of computed tomography images and 3D measurements were performed for glenoid (version and inclination) and acromion (tilt, coverage, height).

Results

Overall, the scapulae of patients with dynamic and static instability differed only marginally among themselves. Compared with the control group, the glenoid was 2.5° (P = .032), respectively, 5.7° (P = .001) more retroverted and 2.9° (P = .025), respectively, 3.7° (P = .014) more downward tilted in dynamic, respectively, static instability. The acromial roof of dynamic instability was significantly higher and on average 6.2° (P = .007) less posterior covering with an increased posterior acromial height of +4.8mm (P = .001). The acromial roof of static instability was on average 4.8° (P = .041) more externally rotated (axial tilt), 7.3° (P = .004) flatter (sagittal tilt), 8.3° (P = .001) less posterior covered with an increased posterior acromial height of +5.8 mm (0.001).

Conclusion

The scapula of shoulders with dynamic and static posterior instability is characterized by an increased glenoid retroversion and an acromion that is shorter posterolaterally, higher, and more horizontal in the sagittal plane. All these deviations from the normal scapula values were more pronounced in static posterior instability.

Arthroscopic Bankart repair with an individualized capsular shift restores physiological capsular volume in patients with anterior shoulder instability

PURPOSE

Capsular volume reduction in the context of anterior arthroscopic shoulder stabilization represents an important but uncontrolled parameter. The aim of this study was to analyse capsular volume reduction by arthroscopic Bankart repair with an individualized capsular shift in patients with and without ligamentous hyperlaxity compared to a control group.

METHODS

In the context of a prospective controlled study, intraoperative capsular volume measurements were performed in 32 patients with anterior shoulder instability before and after arthroscopic Bankart repair with an individualized capsular shift. The results were compared to those of a control group of 50 patients without instability. Physiological shoulder joint volumes were calculated and correlated with biometric parameters (sex, age, height, weight and BMI).

RESULTS

Patients with anterior shoulder instability showed a mean preinterventional capsular volume of 35.6 ± 10.6 mL, which was found to be significantly reduced to 19.3 ± 5.4 mL following arthroscopic Bankart repair with an individualized capsular shift (relative capsular volume reduction: 45.9 ± 21.9%; P < 0.01). Pre-interventional volumes were significantly greater in hyperlax than in non-hyperlax patients, while post-interventional volumes did not differ significantly. The average shoulder joint volume of the control group was 21.1 ± 7.0 mL, which was significantly correlated with sex, height and weight (P < 0.01). Postinterventional capsular volumes did not significantly differ from those of the controls (n.s.).

CONCLUSION

Arthroscopic Bankart repair with an individualized capsular shift enabled the restoration of physiological capsular volume conditions in hyperlax and non-hyperlax patients with anterior shoulder instability. Current findings allow for individual adjustment and intraoperative control of capsular volume reduction to avoid over- or under correction of the shoulder joint volume. Future clinical studies should evaluate, whether individualized approaches to arthroscopic shoulder stabilization are associated with superior clinical outcome.

Shoulder Position During Magnetic Resonance Arthrogram Significantly Affects Capsular Measurements

PURPOSE

To determine whether change in shoulder position between internal rotation (IR) and external rotation (ER) during magnetic resonance arthrography (MRA) affects previously defined capsular measurements and to determine the utility of rotation in the diagnosis of instability.

METHODS

A retrospective study was conducted of patients who received a shoulder MRA with humeral IR and ER views. Patients with an arthroscopically confirmed diagnosis of instability and those with clinically stable shoulders, no history of instability, and no MRA findings of instability were identified and compared. Humeral rotation, glenoid retroversion, humeral head subluxation, capsular length, and capsular area using axial sequences of IR and ER views were recorded. Analysis compared IR, ER, and Δ capsular measurements between groups using independent t tests and univariate and multivariate regression.

RESULTS

Thirty-one subjects who were diagnosed with instability were included, along with 28 control subjects. Capsular length, capsular area, and humeral subluxations were significantly greater with ER compared with IR views (P < .001, P < .001, P < .001). Patients with instability displayed greater ER capsular length (P = .0006) and ER capsular area (P = .005) relative to controls. Multivariate logistic regression identified age, weight, sex, ER capsular length, and retroversion to be significant predictors of instability. ER capsular length independently predicts instability with 86% sensitivity and 84% specificity. Interobserver reliability using the intraclass correlation coefficient was rated good or excellent on all measurements.

CONCLUSION

Variance in humeral rotation during shoulder MRA significantly affects capsular measurements. Rotational views increase the utility of capsular measurements when assessing for instability, particularly capsular length and capsular area. The implementation of ER positioning enhances the ability to examine capsular changes of the shoulder joint and can assist in the diagnosis of instability.

LEVEL OF EVIDENCE

III, retrospective comparative study.

Editorial Commentary: There Is Value in Standardizing the Position of the Arm During Magnetic Resonance Imaging Arthrogram of the Shoulder When Evaluating for Suspected Instability (and It Doesn't Have to Be Painful to the Patient!)

Evaluating and treating a shoulder with suspected instability remains a challenge for all. Most authors and surgeons would agree that clinical history and physical examination of the patient are the most important aspects of this evaluation. Over the past 15 years, however, radiographic imaging has become a much more prevalent (and essential) component. Magnetic resonance imaging arthrogram has become the gold standard to evaluate a patient for suspected instability and is currently considered the most appropriate advanced study by the American College of Radiologists to do so in both traumatic and atraumatic presentations.

[Short-term effectiveness of arthroscopically capsular vertical mattress suturing for shoulder recurrent anterior dislocation combined with joint laxity]

OBJECTIVE

To evaluate the short-term effectiveness of arthroscopically capsular vertical mattress suturing for shoulder recurrent anterior dislocation combined with joint laxity.

METHODS

A retrospective analysis was performed on 6 shoulder recurrent anterior dislocation patients combined with joint laxity treated with arthroscopically capsular vertical mattress suturing between January 2017 and December 2018. There were 5 males and 1 female with an average age of 20.8 years (range, 19-24 years). The number of shoulder dislocation was 3-18 times, with an average of 9.5 times. The disease duration ranged from 2 to 60 months, with an average of 25.3 months. The preoperative Beighton score was 4-7, with an average of 5.8; the Instability Severity Index Score (ISIS) was 2-5, with an average of 3.5. There were 5 cases of simple Bankart injury and 1 case of bony Bankart injury. The range of motion of shoulder joint (including active flexion and lifting, external rotation, abduction and external rotation, and internal ratation) was recorded before operation and at last follow-up; Oxford shoulder instability score, Rowe shoulder instability score, and Simple Shoulder Test (SST) score were used to evaluate shoulder joint function before operation, at 6 months after operation, and at last follow-up, and complications were recorded.

RESULTS

All patients were followed up 16-28 months (mean, 19.3 months). During the follow-up, all patients had satisfactory motor function, and no re-dislocation and postoperative neurovascular complications occurred. At last follow-up, the activities of active external rotation and abduction and external rotation were significantly improved when compared with those before operation ( P<0.05); the activities of active flexion and lifting and internal rotation were not limited before and after operation, and the difference was not significant ( P>0.05). The Oxford shoulder instability score, Rowe shoulder instability score, and SST score at 6 months after operation and at last follow-up were significantly improved when compared with those before operation ( P<0.05); there was no significant difference between at 6 months after operation and at last follow-up ( P>0.05).

CONCLUSION

The treatment of shoulder recurrent anterior dislocation combined with joint laxity by arthroscopically vertical matress suturing can achieve good short-term effectiveness.

Effect of Posterior Glenoid Bone Loss and Retroversion on Arthroscopic Posterior Glenohumeral Stabilization

BACKGROUND

Posterior glenohumeral instability is an increasingly recognized cause of shoulder instability, but little is known about the incidence or effect of posterior glenoid bone loss.

PURPOSE

To determine the incidence, characteristics, and failure rate of posterior glenoid deficiency in shoulders undergoing isolated arthroscopic posterior shoulder stabilization.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

All patients undergoing isolated posterior labral repair and glenoid-based capsulorrhaphy with suture anchors between 2008 and 2016 at a single institution were identified. Posterior bone deficiency was calculated per the best-fit circle method along the inferior two-thirds of the glenoid by 2 independent observers. Patients were divided into 2 groups: minimal (0%-13.5%) and moderate (>13.5%) posterior bone loss. The primary outcome was reoperation for any reason. The secondary outcomes were military separation and placement on permanent restricted duty attributed to the operative shoulder.

RESULTS

A total of 66 shoulders met the inclusion criteria, with 10 going on to reoperation after a median follow-up of 16 months (range, 14-144 months). Of the total shoulders, 86% (57/66) had ≤13.5% bone loss and 14% (9/66) had >13.5%. Patients with moderate posterior glenoid bone loss had significantly greater retroversion (-11.5° vs -4.3°; P = .01). Clinical failure requiring reoperation was seen in 10.5% of patients in the minimal bone deficiency group and 44.4% in the moderate group (P = .024). There was no difference between groups in rate of military separation or restricted duty. Patients with moderate posterior glenoid bone deficiency were more likely to be experiencing instability instead of pain on initial presentation (P < .001), were more likely to have a positive Jerk test result (P = .05), and had increased glenoid retroversion (P = .01).

CONCLUSION

In shoulders with moderate glenoid bone deficiency (>13.5%) and increased glenoid retroversion, posterior capsulolabral repair alone may result in higher reoperation rates than in shoulders without bone deficiency.

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.

Labral Morphology and Number of Preoperative Dislocations Are Associated With Recurrent Instability After Arthroscopic Bankart Repair

PURPOSE

To develop a method to measure capsule and labral volume on preoperative magnetic resonance imaging to predict surgical failure after primary Bankart repair.

METHODS

A retrospective case-control study was conducted on patients undergoing primary anterior arthroscopic shoulder stabilization. Surgical failure was defined as a recurrent dislocation event. Cases were matched to controls based on age and sex in a 1:2 ratio. Preoperative magnetic resonance (MR) arthrograms were analyzed by 2 trained reviewers using Vitrea software to measure labral and capsular volume with a 3-dimensional model. Labral size was also qualitatively measured on axial images. A "diffusely small" labrum was defined as labral height less than the width of the glenoid tidemark cartilage.

RESULTS

Of the 289 patients who had an arthroscopic Bankart repair from 2006 to 2015, 33 who had a postoperative dislocation met the inclusion criteria and were matched to 62 control patients who did not. There was no difference between groups with regard to age (P = .88), sex (P = .82), contact sport participation (P = .79), proportion of overhead athletes (P = .33), proportion of throwers (P = 1), surgical positioning in lateral decubitus (P = .18), or number of repair anchors used (P = .91). The average number of preoperative dislocations was significantly higher in the failure group (3.2 vs. 2.0, P < .0001). In patients with normal labrum morphology, the odds of having surgical failure increased by 26% for a 1-unit increase in the number of prior dislocations (odds ratio [OR] 1.26, 95% confidence interval [CI] 1.02 to 1.55). The case and control groups had similar labral and capsular volume as measured in Vitrea. The failure group had a significantly higher proportion of patients with a diffusely small labral morphology (47% vs. 17%, P = .03). Controlling for number of preoperative dislocations, the odds of having a diffusely small labral morphology was 3.2 times more likely in the case group than the control group (95% CI 1.259 to 8.188). Interrater reliability between 2 independent reviewers was excellent for measurement of capsule volume (r = 0.91) and good for measurement of labral volume (r = 0.74).

CONCLUSIONS

This study presents a novel method of measuring labral and capsule volume with high interrater reliability. An increased number of recurrent dislocations prior to primary Bankart repair was associated with increased odds of recurrent instability after surgery. The OR for failure also increased with increasing number of preoperative dislocations. Diffusely small labral morphology was associated with having a postoperative redislocation.

LEVEL OF EVIDENCE

III (case-control study).

The Incidence of Traumatic Posterior and Combined Labral Tears in Patients Undergoing Arthroscopic Shoulder Stabilization

BACKGROUND

Posterior and combined shoulder instabilities have been reported as accounting for only 2% to 5% of cases. More recently, an increased incidence of posterior capsulolabral tear has been reported.

PURPOSE

To assess the incidence of posterior and combined labral tears in a large cohort of patients with surgically treated shoulder labral tears.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

This was a retrospective study that evaluated 442 patients who underwent an arthroscopic capsulolabral repair over a 3-year period. Patients were categorized according to the location of their labral tear and whether their injury was sustained during sporting or nonsporting activity. Proportions of labral tears between sporting and nonsporting populations were compared using the chi-square test.

RESULTS

Patients had a mean age of 25.9 years and 89.6% were male. Isolated anterior labral tears occurred in 52.9%, with posterior and combined anteroposterior labral tears accounting for 16.3% and 30.8%, respectively. The frequency of posterior and combined lesions was greater in the sporting population compared with the nonsporting population (P = .013).

CONCLUSION

Posterior and combined labral tears are more prevalent than previously reported, particularly in the sporting population.

Evaluation of Inferior Capsular Laxity in Patients with Atraumatic Multidirectional Shoulder Instability with Magnetic Resonance Arthrography

OBJECTIVE

To compare inferior capsular redundancy by using magnetic resonance arthrography (MRA) images in patients with multidirectional instability (MDI) of the shoulder and control subjects without instability and thereby develop a screening method to identify the presence of shoulder MDI.

MATERIALS AND METHODS

The MRA images of patients with MDI of the shoulder (n = 65, 57 men, 8 women; mean age, 24.5 years; age range, 18-42 years) treated over an eight-year period were retrospectively reviewed; a control group (n = 65, 57 men, 8 women; mean age, 27.4 years; age range, 18-45 years) without instability was also selected. The inferior capsular redundancy was measured using a new method we named the glenocapsular (GC) ratio method. MRA images of both groups were randomly mixed together, and two orthopedic surgeon reviewers measured the cross-sectional areas (CSAs) and sagittal capsule-head ratios on oblique sagittal images, as well as the axial capsule-head ratios on axial images and GC ratios on oblique coronal images.

RESULTS

The CSAs and GC ratios were significantly higher in patients than in controls (both, p < 0.001); however, the sagittal capsule-head ratios and axial capsule-head ratios were not significantly different (p = 0.317, p = 0.053, respectively). In addition, GC ratios determined the presence of MDI more sensitively and specifically than did CSAs. A GC ratio of > 1.42 was found to be most suggestive of MDI of the shoulder, owing to its high sensitivity (92.3%) and specificity (89.2%).

CONCLUSION

GC ratio can be easily measured and used to accurately screen for MDI of the shoulder.

Three-dimensional Capsular Volume Measurements in Multidirectional Shoulder Instability

Background

In a previous study undertaken to quantify capsular volume in rotator cuff interval or axillary pouch, significant differences were found between controls and patients with instability. However, the results obtained were derived from two-dimensional cross sectional areas. In our study, we sought correlation between three-dimensional (3D) capsular volumes, as measured by magnetic resonance arthrography (MRA), and multidirectional instability (MDI) of the shoulder.

Methods

The MRAs of 21 patients with MDI of the shoulder and 16 control cases with no instability were retrospectively reviewed. Capsular areas determined by MRA were translated into 3D volumes using 3D software Mimics ver. 16 (Materilise, Leuven, Belgium), and glenoid surface area was measured in axial and coronal MRA views. Then, the ratio between capsular volume and glenoid surface area was calculated, and evaluated with control group.

Results

The ratio between 3D capsular volume and glenoid surface area was significantly increased in the MDI group (3.59 ± 0.83 cm³/cm²) compared to the control group (2.53 ± 0.62 cm³/cm²) (p<0.01).

Conclusions

From these results, we could support that capsular volume enlargement play an important role in MDI of the shoulder using volume measurement.

Age-Related Changes of Elastic Fibers in Shoulder Capsule of Patients with Glenohumeral Instability: A Pilot Study

Background

Recurrent shoulder dislocations occur much more frequently in adolescents than in the older population but a clear explanation of this incidence does not exist. The aim of the present study was to define the age-related distribution of the elastic fibers (EFs) in the shoulder capsule's extracellular matrix as a factor influencing shoulder instability.

Materials and Methods

Biopsy specimens were obtained from the shoulder capsule of patients divided preoperatively into three groups: Group 1 consisted of 10 male patients undergoing surgery for unidirectional traumatic anterior instability (TUBS); Group 2 consisted of 10 male patients undergoing surgery for multidirectional instability (MDI); Group 3 represents the control, including 10 patients with no history of instability. In addition to the group as a whole, specific subgroups were analyzed separately on the basis of the age of subjects: > 22 or < to 22 years. All the samples were analyzed by histochemical (Weigert's resorcinol fuchsin and Verhoeff's iron hematoxylin), immunohistochemical (monoclonal antielastin antibody), and histomorphometric methods.

Results

Both the elastin density and the percentage of area covered by EFs were significantly higher in younger subjects (<22 years old). Furthermore, the elastin density and the percentage of area covered by EFs were significantly higher in specimens of group of patients affected by multidirectional shoulder instability in comparison to the other two groups.

Conclusion

Data of the present study confirmed the presence of an age-related distribution of EFs in the human shoulder capsule. The greater amount of EFs observed in younger subjects and in unstable shoulders could play an important role in predisposing the joint to first dislocation and recurrence.

Arthroscopic treatment of posterior shoulder instability in patients with and without glenoid dysplasia: a comparative outcomes analysis

BACKGROUND

The purpose of this study was to evaluate the influence of glenoid dysplasia on outcomes after isolated arthroscopic posterior labral repair in a young military population.

METHODS

Thirty-seven male patients who underwent arthroscopic posterior labral repair for symptomatic posterior shoulder instability were evaluated at a mean duration of 3.1 years. A comparative analysis was performed for those with glenoid dysplasia and without dysplasia. Additional factors analyzed included military occupational specialty (MOS), preoperative mental health clinical encounters and mental health medication use, and radiographic characteristics (version, posterior humeral head subluxation, and posterior capsular area) on a preoperative standard shoulder magnetic resonance arthrogram. The groups were analyzed with regard to shoulder outcome scores (subjective shoulder value [SSV], American Shoulder and Elbow Surgeons [ASES] rating scale, Western Ontario Shoulder Instability Index [WOSI]), need for revision surgery, and medical separation from the military.

RESULTS

Of 37 patients, 3 (8.1%) underwent revision surgery and 6 (16%) underwent medical separation. Overall outcome assessment demonstrated a mean SSV of 67.9 (range, 25-100) ± 22.1, mean ASES of 65.6 (range, 15-100) ±  22, and mean WOSI of 822.6 (range, 5-1854) ± 538. There were no significant differences in clinical outcome scores between the glenoid dysplasia and no dysplasia groups (SSV, P = .55; ASES, P = .57; WOSI, P = .56). MOS (P = .02) and a history of mental health encounters (P = .04) were significantly associated with diminished outcomes.

CONCLUSIONS

The presence or absence of glenoid dysplasia did not influence the outcome after arthroscopic posterior labral repair in a young military population. However, a history of mental health clinical encounters and an infantry MOS were significantly associated with poorer clinical outcomes.

[Diagnostics and treatment of posterior shoulder instability]

Posterior shoulder instability has a markedly lower incidence than anterior shoulder instability. It has a wide spectrum of clinical symptom manifestations and the overwhelming number of patients lack a traumatic primary dislocation. In addition to a detailed medical history, a specific clinical examination with the help of standardized provocation tests is essential for the diagnostics. For the detection of structural posterior capsule and labral lesions in cases of chronic courses, magnetic resonance imaging (MRI) should be used with an intra-articular contrast agent. Relevant bony defects of the humeral head (reverse Sachs-Hill lesion) are frequent, whereas critical posterior defects of glenoid cavity are relatively rare. Both lesions should be quantified using 3D computed tomography. The choice of therapeutic procedure should be based on the underlying pathology of the defect. Conservative therapy is useful in patients with scapular dyskinesis, voluntary dislocation and pathological muscle patterning. In isolated soft tissue pathologies, arthroscopic labrum fixation and capsule plication are the standard treatment. In the case of insufficient soft tissue relations or critical posterior glenoid defects, bony stabilization of the glenoid using an iliac crest bone graft is the recommended therapy.

Posterior Glenohumeral Instability: Evidence-based Treatment

Posterior glenohumeral instability is an increasingly important clinical finding in athletic patients. Over the last decade, basic and clinical research has improved our understanding of the pathoanatomy and biomechanics of this challenging disorder, as well as our ability to diagnose and appropriately treat it. Although recurrent posterior shoulder instability is not as common as anterior instability, it is prevalent among specific populations, including football and rugby players, and may be overlooked by clinicians who are unaware of the typical physical examination and radiographic findings.

Overuse Injuries of the Pediatric and Adolescent Throwing Athlete

In the hypercompetitive environment of year round youth baseball, arm pain is commonplace. Although much research has been done about injuries in the overhead throwing athlete, the emphasis has been on the more elite levels, where athletes have reached full development. The anatomy of the skeletally immature athlete, including open physeal plates and increased tissue laxity, raises unique issues in the presentation and treatment of repetitive throwing injuries of the elbow and shoulder. With a focus on "little leaguers," this discussion evaluates five of the most common elbow and shoulder injuries-Little Leaguer's elbow, ulnar collateral ligament sprain or tear, osteochondritis dissecans/Panner's disease, Little Leaguer's shoulder, and multidirectional instability. In the developmentally distinct pediatric athlete, pathogenesis, diagnosis, and treatment may differ from that established for adults. Offering early diagnosis and treatment appropriate to a child's level of development will enable youth to not only continue to play sports but to also maintain full functionality as active adults.

Arthroscopic Pancapsular Shift With Labral Repair for Multidirectional Instability of the Shoulder

Initial treatment of shoulder multidirectional instability (MDI) consists of nonoperative modalities of physical therapy and rehabilitation; if this fails, surgical treatment can become necessary. MDI of the shoulder can be challenging to manage in individuals who fail conservative management. Historically, surgical treatment for MDI has been open capsular plication; however, arthroscopic capsular plication has now become the standard of care, with outcomes similar to the open procedure. The purpose of this article and Video 1 is to describe our arthroscopic technique for pancapsular shift with labral repair.

Critical Findings on Magnetic Resonance Arthrograms in Posterior Shoulder Instability Compared With an Age-Matched Controlled Cohort

BACKGROUND

Posterior shoulder instability is less common and potentially more difficult to diagnose clinically and radiographically compared with anterior shoulder instability. Radiographic findings including posterior labral tears, increased retroversion, presence of glenoid dysplasia, and increased capsular area are associated with symptomatic recurrent posterior shoulder instability.

PURPOSE

This study aimed to determine the prevalence and severity of associated radiographic parameters found on magnetic resonance arthrograms (MRAs) in patients with arthroscopically confirmed isolated posterior labral tears and symptomatic recurrent posterior shoulder instability, compared with an age-matched cohort of patients without posterior instability or labral injury confirmed with shoulder arthroscopy.

STUDY DESIGN

Cross-sectional study, Level of evidence, 3.

METHODS

Patients who received a preoperative standard shoulder MRA at an academic institution over a 5-year period and had symptomatic posterior instability and received a repair of an arthroscopically confirmed posterior labral tear (n = 63) were identified. These patients were compared with an age-matched control group of patients without posterior instability (n = 49) who underwent an isolated arthroscopic distal clavicle resection that included an arthroscopic glenohumeral joint evaluation. Glenoid version, posterior humeral head subluxation, glenoid dysplasia, and linear and capsular area measurements were evaluated between the 2 groups. Interobserver reliability for continuous and categorical variables was assessed for all measurements.

RESULTS

Multivariate logistic regression revealed that the presence of increased glenoid retroversion (P = .0018), glenoid dysplasia (P = .03), and increased axial posterior capsular cross-sectional area (P = .05) were significantly associated with posterior labral tears and symptomatic posterior shoulder instability compared with the age-matched control group. Posterior humeral head subluxation was found to be a statistically significant variable with univariate analysis (P = .001) for posterior shoulder instability but not with multivariate logistic regression (P = .53). Interobserver reliability was good to very good for all measurements (intraclass correlation coefficient [ICC] = 0.74-0.85; κ = 0.64) but was moderate for total capsular area and sagittal capsular area measurements (ICC = 0.43-0.56).

CONCLUSION

The presence of increased glenoid retroversion, glenoid dysplasia, and increased posterior capsular area on MRA are significantly associated with posterior labral tears and symptomatic posterior shoulder instability. Identification of these critical radiographic variables on magnetic resonance arthrography assists in the accurate diagnosis and management of clinically significant posterior shoulder instability.

A new screening method for multidirectional shoulder instability on magnetic resonance arthrography: labro-capsular distance

OBJECTIVE

To compare the capsular dimension as measured on magnetic resonance arthrography (MRA) between patients with multidirectional instability (MDI) of the shoulder and control subjects without instability. Ultimately, we aimed to develop an easy and reliable new screening method to assess MDI of the shoulder using MRA.

MATERIALS AND METHODS

MRA images of patients with MDI of the shoulder (n = 25) during a 6-year period (February 2010 to May 2015) were retrospectively reviewed. A control group (n = 26) without instability was also identified. The capsular area was measured using a new screening method we termed labro-capsular (LC) distance. MRA images of the two groups were randomly mixed, and two orthopedic surgeon reviewers recorded anterior, posterior, and inferior LC distance measurements on axial and coronal images using a mid-glenoid cut.

RESULTS

The inferior LC distance increased significantly in the patient group versus control group (P < 0.001), but there were no statistically significant differences in the anterior (P = 0.1165) and posterior (P = 0.5229) LC distances. An inferior LC distance >16.88 mm is most suggestive of MDI of the shoulder because of its high sensitivity (76 %) and specificity (96 %).

CONCLUSION

The inferior LC distance can be easily and quickly measured and used as an effective clinical screening method for atraumatic MDI of the shoulder.

Quantification and correlation of hip capsular volume to demographic and radiographic predictors

PURPOSE

The purpose of this study was to develop a novel method to quantify hip capsular volume in patients undergoing hip arthroscopic surgery, utilizing magnetic resonance arthrogram (MRA) and to determine whether there are demographic or radiological factors that are associated with capsular volume.

METHODS

A retrospective review was performed from 2006 to 2014 of consecutive patients who presented with hip pain and received a hip MRA and plain radiographs. All patients were suspected of soft tissue injury due to underlying femoroacetabular impingement (FAI). A novel technique using Osirix MD for the quantification of capsular and femoral head volumes was described.

RESULTS

Ninety-seven patients met the study criteria and were included for analysis. The average total capsular volume (including the femoral head) measured 79.89 ± 20.35 cm(3), average femoral head volume 46.68 ± 12.32 cm(3), and average true capsular volume measured 33.20 ± 12.58 cm(3). Average total capsular:femoral head volume ratio was 1.74 ± 0.27. Significant differences were seen between genders for total capsular volume (P < 0.01), femoral head volume (P < 0.01), and true capsular volume (P < 0.01). Total capsular volume:femoral head ratio was greater for females, but was not statistically significant (n.s.). Femoral head volume significantly correlated with alpha angle (P < 0.01), height (P < 0.01), BMI (P < 0.01), BMI (P = 0.02), and age (P < 0.01). Total capsular volume significantly correlated with height (P < 0.01), BMI (P = 0.01), and age (P < 0.01). Age was also correlated with true capsular volume (P = 0.011). No significant differences in capsular volumes were found between normal and abnormal radiographic measurements.

CONCLUSION

The current study describes a reproducible radiographic measurement for hip capsule volumes from MRAs. Only gender was predictive of total capsular volume, femoral head volume, and true capsular volume. There were no macroscopic anatomical differences evident on MRA. This method showed good intra- and inter-observer reliability and can aid in future research regarding hip capsule volumes. This novel technique may potentially allow clinicians a readily available and reliable method to detect large and redundant capsules, a possible predisposition for hip micro-instability.

LEVEL OF EVIDENCE

Retrospective case series, Level IV.

Factors affecting capsular volume changes and association with outcomes after Bankart repair and capsular shift

BACKGROUND

Capsular laxity is a main contributing factor in recurrent shoulder instability and is suggested to be correlated with increased capsular volume. Arthroscopic capsular shift combined with Bankart repair can reduce the capsular volume and reinforce the redundant capsule; however, as the capsuloligamentous structure has viscoelastic properties, it is possible for the shifted and tensioned capsule of the glenohumeral joint to slowly stretch out again over time, resulting in an increase in capsular volume.

PURPOSE

To analyze changes in capsular volume of the glenohumeral joint over time after arthroscopic Bankart repair and capsular shift, the factors associated with these changes, and their relevance to outcomes.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Included in this study were 105 patients (mean age, 25.8 ± 8.2 years) who underwent arthroscopic Bankart repair and capsular shift for anterior shoulder instability and computed tomography arthrography (CTA) at 3 months and 1 year postoperatively and whose various functional outcomes were evaluated preoperatively and at the last follow-up (>12 months). Among these patients, 27 also had preoperative CTA. These 27 patients were used to make comparisons between preoperative and 3-month postoperative CTA measurements, and all 105 patients were used for all other comparisons. Two raters measured the separate anterior and posterior capsular volume and cross-sectional area at the 5-o'clock position using 3-dimensional (3D) Slicer software. These measurements were subsequently adjusted for each glenoid size. The changes in capsular volume and cross-sectional area at the 5-o'clock position over time, the factors related to higher change in anterior capsular volume, and their correlation with outcomes were evaluated.

RESULTS

Three months postoperatively, the total and anterior capsular volume and anterior cross-sectional area significantly decreased; however, these values increased again at 1 year postoperatively (all P < .01). The inter- and intraobserver reliabilities of the measurements were excellent (interclass correlation coefficient = 0.717-0.945). Female sex, being an elite athlete, and more dislocations before surgery were related to a higher increase in anterior capsular volume at 1 year (all P < .05). Eight patients had redislocation, and 18 exhibited positive apprehension test postoperatively, and these patients showed significantly higher increases in anterior and total capsular volume at 1 year than did those without redislocation or positive apprehension sign (all P < .01). However, with the exception of Rowe score, a higher increase in anterior capsular volume was not related to functional outcome measures.

CONCLUSION

Surgeons should be aware of the re-increase in anterior capsular volume or restretching trait of the anterior capsule over time, even after successful arthroscopic Bankart repair and capsular shift. In this study, women, elite athletes, and those with frequent dislocations were at high risk of capsular restretching. An increase in capsular volume was related to redislocation and positive apprehension sign as well as with Rowe score.

Multidirectional instability of the shoulder: biomechanics, clinical presentation, and treatment strategies

Multidirectional instability (MDI) of the shoulder is a condition where the dislocation occurs in more than one direction with minimal or no causative trauma. Its pathoanatomy is complex and characterized by a redundant capsule, resulting in increased glenohumeral joint volume. The fact that several further factors may contribute to symptom onset complicates the diagnosis and hampers the identification of a therapeutic approach suitable for all cases. There is general agreement that the initial treatment should be conservative and that surgery should be reserved for patients who have not responded to an ad hoc rehabilitation program. We review the biomechanics, clinical presentation, and treatment strategies of shoulder MDI.

Pediatric and adolescent shoulder instability

Instability of the shoulder is a common issue faced by sports medicine providers caring for pediatric and adolescent patients. A thorough history and physical examination can help distinguish traumatic instability from multidirectional or voluntary instability. A systematic understanding of the relevant imaging characteristics and individual patient disease and goals can help guide initial treatment. Given the high risk of recurrent instability, young, active patients who seek to return to competitive contact sports should consider arthroscopic stabilization after a first-time instability event. MDI should be treated initially with conservative rehabilitation. Patients who fail extensive conservative treatment may benefit from surgical stabilization. Arthroscopic techniques may now approach the results found from traditional open capsular shift procedures. Future studies should be designed to examine the outcomes in solely pediatric and adolescent populations after both conservative and operative treatment of shoulder instability.

MR arthrography including abduction and external rotation images in the assessment of atraumatic multidirectional instability of the shoulder

OBJECTIVE

To evaluate diagnostic signs and measurements in the assessment of capsular redundancy in atraumatic multidirectional instability (MDI) of the shoulder on MR arthrography (MR-A) including abduction/external rotation (ABER) images.

METHODS

Twenty-one MR-A including ABER position of 20 patients with clinically diagnosed MDI and 17 patients without instability were assessed by three radiologists. On ABER images, presence of a layer of contrast between the humeral head (HH) and the anteroinferior glenohumeral ligament (AIGHL) (crescent sign) and a triangular-shaped space between the HH, AIGHL and glenoid (triangle sign) were evaluated; centring of the HH was measured. Anterosuperior herniation of the rotator interval (RI) capsule and glenoid version were determined on standard imaging planes.

RESULTS

The crescent sign had a sensitivity of 57 %/62 %/48 % (observers 1/2/3) and specificity of 100 %/100 %/94 % in the diagnosis of MDI. The triangle sign had a sensitivity of 48 %/57 %/48 % and specificity of 94 %/94 %/100 %. The combination of both signs had a sensitivity of 86 %/90 %/81 % and specificity of 94 %/94 %/94 %. A positive triangle sign was significantly associated with decentring of the HH. Measurements of RI herniation, RI width and glenoid were not significantly different between both groups.

CONCLUSIONS

Combined assessment of redundancy signs on ABER position MR-A allows for accurate differentiation between patients with atraumatic MDI and patients with clinically stable shoulders; measurements on standard imaging planes appear inappropriate.

KEY POINTS

MR arthrography has the possibility to accurately identify patients with atraumatic MDI. Imaging of the shoulder in abduction and external rotation provides additive information. Capsular enlargement of the shoulder can be diagnosed on MR arthrography.

Multidirectional instability of the shoulder: rotator interval dimension and capsular laxity evaluation using MR arthrography

OBJECTIVES

To compare the rotator interval and capsular dimension as measured on MR arthrography between patients with clinically diagnosed multidirectional instability (MDI) and control subjects with no instability.

MATERIALS AND METHODS

We retrospectively reviewed a consecutive series of 658 shoulders that had undergone MR arthrography between 2006 and 2010. Of these, 97 shoulders were included in the present study. These shoulders were divided into two groups according to the clinically established diagnoses. The MDI group comprised 47 shoulders with atraumatic multidirectional shoulder instability, and the control group comprised 50 shoulders with no instability. Two independent observers measured the width and depth of the rotator interval, and the capsular dimensions at the anterior, anteroinferior, inferior, posteroinferior, and posterior regions in the two groups using MR arthrography.

RESULTS

The rotator interval width and depth were significantly greater in the MDI group (width, observer 1, 17.7 mm, observer 2, 17.9 mm; depth, observer 1, 8.9 mm, observer 2, 8.8 mm) than in the control group (width, observer 1, 14.3 mm, observer 2, 14.5 mm; depth, observer 1, 5.9 mm, observer 2, 6.2 mm) (p < .001). The capsular dimensions at the inferior and posteroinferior regions were significantly larger in the MDI group (inferior, observer 1, 27.9 mm, observer 2, 27.8 mm; posteroinferior, observer 1, 27.0 mm, observer 2, 27.1 mm) than in the control group (inferior, observer 1, 25.7 mm, observer 2, 25.3 mm; posteroinferior, observer 1, 23.3 mm, observer 2, 23.6 mm) (p < .05). A width greater than 15.2 mm or a depth greater than 6.4 mm of the rotator interval, suggesting MDI, had sensitivities of 81 and 92 % for observer 1, and 79 and 94 % for observer 2, and specificities of 66 and 72 % for observer 1, and 62 and 66 % for observer 2, respectively.

CONCLUSIONS

Measurements of the rotator interval and the size of the distended inferior and posteroinferior joint capsule on MR arthrography are greater in shoulders with clinical MDI than in stable shoulders.