Quadrilateral space syndrome: the Mayo Clinic experience with a new classification system and case series

Sports-related peripheral nerve injuries of the upper limb

Peripheral nerve injuries in athletes affect the upper limb more commonly than the lower limb. Common mechanisms include compression, traction, laceration, and ischemia. Specific sports can have unique mechanisms of injury and are more likely to be associated with certain neuropathies. Familiarity with these sport-specific variables and recognition of the common presentations of upper limb neuropathic syndromes are important in assessing an athlete with a suspected peripheral nerve injury. Evaluation may require imaging modalities and/or electrodiagnostic testing to confirm a nerve injury. In some cases, diagnostic injections may be needed to differentiate neuropathic versus musculoskeletal etiology. Early and accurate diagnosis is essential for treatment/management and increases the likelihood of a safe return-to-sport and avoidance of long-term functional consequences. Most nerve injuries can be treated conservatively, however, severe or persistent cases may require surgical intervention. This monograph reviews key diagnostic, management, and preventative strategies for sports-related peripheral nerve injuries involving the upper limb.

Thoracic outlet syndrome in overhead athletes

Background

We aimed to retrospectively compare the clinical outcomes of endoscopy-assisted first-rib resection for thoracic outlet syndrome (TOS) between overhead athletes and nonathletes and investigate the return to same-level sports rate in overhead athletes.

Methods

We retrospectively reviewed 181 cases with TOS (75 women, 106 men; mean age, 28.4 years; range, 12-57 years) who underwent endoscopy-assisted first-rib resection. We divided into two groups: 79 overhead athletes and 102 nonathletes groups. A transaxillary approach for first-rib resection and neurovascular decompression was performed under magnified visualization. Endoscopic findings related to the neurovascular bundle, interscalene distance, and scalene muscle were evaluated intraoperatively. We assessed the Roos and Disability of the Arm, Shoulder, and Hand scores, return to same-level sports rate, and ball velocity.

Results

Overhead athletes were significantly more likely to be men, younger, used the dominant side more frequently, and have a larger physique, more shoulder and elbow pain, and shorter symptom duration. The outcomes of the Roos score revealed significant differences in excellent or good results between overhead athletes (91.1%) and nonathletes (62.8%). The two groups significantly differed in preoperative and postoperative Disability of the Arm, Shoulder, and Hand and recovery rate scores (P = .007, < .001, < .001).

Conclusion

Overhead athletes with TOS were more likely to be men, younger, dominant side more frequently, and have more shoulder and elbow pain, and a shorter symptom duration. Endoscopy-assisted transaxillary first-rib resection and neurolysis provided superior clinical outcomes in overhead athletes with TOS compared with nonathletes and a high return-to-same-level-play rate in sports.

Upper-limb neurovascular compression, pectoralis minor and quadrilateral space syndromes: A narrative review of current literature

Pectoralis minor syndrome (PMS) and quadrilateral space syndrome (QSS) are uncommon neurovascular compression disorders affecting the upper extremity. PMS involves compression under the pectoralis minor muscle, and QSS results from compression in the quadrilateral space-both are classically observed in overhead-motion athletes. Diagnosing PMS and QSS may be challenging due to variable presentations and similarities with other, more common, upper-limb pathologies. Although there is no gold standard diagnostic, local analgesic muscle-block response in a patient with the appropriate clinical context is often all that is required for an accurate diagnosis after excluding more common etiologies. Treatment ranges from conservative physical therapy to decompressive surgery, which is reserved for refractory cases or severe, acute vascular presentations. Decompression generally yields favorable outcomes, with most patients experiencing significant relief and restored baseline function. In conclusion, PMS and QSS, although rare, can cause debilitating upper-extremity symptoms; accurate diagnosis and appropriate treatment offer excellent outcomes, alleviating pain and disability.

Teres minor denervation and pathologies resulting in shoulder joint instability and rotator cuff tears: A retrospective cross-sectional MRI study

Teres minor denervation (TMD) has gained increasing attention in recent years, particularly with the advent of magnetic resonance imaging (MRI). The potential association between TMD and shoulder instability or rotator cuff tear remains a subject of interest in the orthopedic community. In this retrospective and cross-sectional study, authors aim to investigate the potential association between TMD and shoulder instability or rotator cuff tears. Authors retrospectively analyzed MRI findings from 105 patients with TMD, focusing on rotator cuff pathologies, posterior labrocapsular complex (PLCC) tears, and posteroinferior glenohumeral joint capsule alterations. Authors assessed the association between TMD and rotator cuff and PLCC tears. For the multivariate analysis, partial proportional odds models were constructed for subscapularis (SSC) and SSP tears. Rotator cuff tears were present in 82.9% of subjects, with subscapularis (SSC) tears being the most frequent (77.1%). A significant association was observed between TMD and rotator cuff pathology (P = .002). PLCC tears were found in 82.3% of patients, and humeral position relative to the osseous glenoid was noted in 60% of patients with TMD. A significant association was identified between TMD and shoulder instability or labral/capsular abnormalities (P < .001). More than half of the cases exhibited a long tethering appearance toward the axillary neurovascular bundle on T1-weighted sagittal images. Our findings suggest that TMD is significantly associated with rotator cuff tears and shoulder instability. This study highlights the importance of identifying and treating PLCC tears in patients with TMD to address shoulder instability. Further research is needed to elucidate the role of TMD in the pathogenesis of shoulder instability and rotator cuff pathology.

[Rare nerve compression neuropathies]

UNCOMMON NERVE COMPRESSION SYNDROMES

In regard to the complex anatomical relationship of peripheral nerves and muscles, tendons, fasciae as well as their long course within those anatomical structures and additional close contact to bony structures, they are prone to suffer from local compression syndromes. Hence creating a vast majority of entrapment syndromes - well described in literature for almost every single nerve. The purpose of this article is to give an overview of symptoms, signs, diagnostic studies and treatment options, addressing especially the less known syndromes. Compression syndromes of the upper arm and shoulder region include the suprascapular nerve syndrome the compression of the axillary nerve within the spatium quadrilaterale and the compression of the long thoracic nerve at the chest wall. The upper extremity offers a variety of infrequent entrapment syndromes, as the pronator teres syndrome and anterior interosseus syndrome, both resulting from pressure to the median nerve in the forearm. Compression neuropathy in the course of the radial nerve in the distal upper extremity is also known as supinator syndrome. Guyon's canal syndrome is the ulnar side equivalent to the well-known carpal tunnel syndrome. In the case of a Cheiralgia paresthetica, a compression of a sensory branch of the superficial radial nerve can be seen. In the lower extremities, a variety of nerves especially in the groin and thigh area can be compressed as they pass through the narrow spaces between the abdominal muscles or underneath the inguinal ligament. Compression of the lateral femoral cutaneous nerve is the most common syndrome. Compression syndromes of the femoral and obturator nerves are most often iatrogenic. Pain around the knee, especially the lateral part and following orthopedic procedures of the knee, can arise from a compression or a lesion of a small infrapatellar branch of the saphenous nerve. Another probably underdiagnosed syndrome is piriformis syndrome, resulting from an entrapment of the sciatic nerve as it passes through certain muscular structures. In the distal lower extremity, the peroneal and tibial nerves can be compressed at multple sites, clinically known as peroneal nerve paralysis resulting from nerve compression around the fibular head, the anterior and posterior tarsal tunnel syndrome, and Morton's metatarsalgia.

Axillary and musculocutaneous neuropathies

This chapter covers axillary and musculocutaneous neuropathies, with a focus on clinically relevant anatomy, electrodiagnostic approaches, etiologic considerations, and management principles. Disorders of the lateral antebrachial cutaneous nerve, a derivative of the musculocutaneous nerve, are also reviewed. We emphasize the importance of objective findings, including the physical examination and electrodiagnostic evaluation in confirming the isolated involvement of each nerve which, along with the clinical history, informs etiologic considerations. Axillary and musculocutaneous neuropathies are both rare in isolation and most frequently occur in the setting of trauma. Less commonly encountered etiologies include external compression or entrapment, neoplastic involvement, or immune-mediated disorders including neuralgic amyotrophy, postsurgical inflammatory neuropathy, multifocal motor neuropathy, vasculitic neuropathy, and multifocal chronic inflammatory demyelinating polyradiculoneuropathy.

Syndromes of Concurrent Hypertension, Diastolic Dysfunction, and Pulmonary or Peripheral Edema in Cardio-Oncology: Case Studies, Literature Review, and New Classification System

OPINION STATEMENT

Individuals who have ever been diagnosed with cancer are at increased risk for cardiovascular conditions during and after cancer treatment. Especially during cancer treatment, cardiovascular conditions can manifest in many ways, including peripheral or pulmonary edema. Edema can indicate volume overload affecting the heart even without other unequivocal evidence of apparent diastolic or systolic left ventricular dysfunction, particularly at rest. We propose a novel algorithm to streamline the diagnostic evaluation and cardiovascular classification for cancer patients with edema. We initially advise prompt evaluation with a chest X-ray and echocardiogram. We then suggest classification into one of five categories based on the timing of presentation of edema relative to cancer treatment, as well as echocardiography results and the presence or absence of hypertension or lymphatic causes of edema. This classification tool can then be utilized to guide further cardiovascular management suggestions. These concurrent syndromes presenting as edema may indicate the development or aggravation of undiagnosed diastolic dysfunction with or without hypertension, even if transiently present only while on cancer treatment.

Posterior circumflex humeral artery pathological lesions with digital ischemia in an elite volleyball player: A case report and literature review

The posterior circumflex humeral artery, a branch of the axillary artery, is compressed by the humeral head during repeated abduction and external rotation of the shoulder joint owing to its anatomical structure. This damages the vascular endothelium, resulting in thrombi, arterial dissection, and aneurysms, a condition known as posterior, circumflex humeral artery pathological lesions. A thrombus may form at the site and becomes a peripheral embolus, resulting in peripheral arterial occlusion.A 21-year-old right-handed elite man college volleyball player noticed coldness and pain in his right hand during a game. Cyanosis was present except in the middle finger, and the beating radial artery was palpable; however, the ulnar artery was not. Doppler ultrasound examination revealed thrombus occlusion of the ulnar artery and common palmar artery of the index finger. Peripheral arterial occlusion was diagnosed due to embolization of a thrombus from this site. The patient stopped practicing volleyball immediately after the onset of symptoms and was started on cilostazol 200 mg and rivaroxaban 15 mg. Subjective coldness of the fingers improved one week after the start of treatment. The patient resumed practice four weeks after the start of treatment and participated in a game by the seventh week.Posterior circumflex humeral artery pathological lesions are caused by overhead motions such as pitching. They are most commonly reported in athletes playing volleyball, although rare, and many cases of aneurysm formation have been reported.Observing a cold sensation in the periphery after practice is necessary for screening.

Quadrangular Space Syndrome: a systematic review of surgical and medical therapeutic advances

Background

The axillary nerve and posterior circumflex humeral artery are compressed in Quadrangular Space Syndrome (QSS), which can be treated with conservative approaches or surgical decompression in recalcitrant instances. There are no clear guidelines for determining which surgical method is optimal for treating QSS and other disorders that mirror QSS.

Objective

The goal of this study is to grade and review past, current, and planned medicinal and surgical care modalities for QSS.

Materials and Methods

The review protocol is registered with PROSPERO (ID: CRD42022332766). To identify recent advances in the methods/techniques of medical and surgical management of QSS, PubMed and Medline databases were searched until March 2022 for publications, including case studies, case reports, and review articles, using medical subject headings terms like quadrilateral space syndrome, surgical management, and medical management. Throughout the study, all the authors scrupulously followed a well-developed registered review process and the risk of bias in systematic reviews guidance tool. Data on proposed medical and surgical management methods/techniques were compiled, and each was analyzed based on the underlying neuro-vascular systems.

Results

There were 88 items found in the first search. Following applying the inclusion and exclusion criteria, 16 papers were chosen for synthesis in the review study after a thorough assessment. Three studies (conservative and advanced) focused on medical care of QSS, while 12 articles (prior, current, and newer) focused on surgical management of QSS. Only four of the 15 studies reviewed proposed different surgical approaches/techniques for surgical decompression in QSS.

Conclusions

There were two regularly used surgical procedures discovered, one anterior/delto-pectoral and the other posterior/ scapular. The anterior route is more technically straightforward and can be employed for surgical QSS decompression.

Vascular Problems in Elite Throwing Athletes

There are approximately 880 and 3,600 major league baseball and minor league baseball players who currently are active in their respective leagues, with thousands of players in the collegiate, high school, and little league ranks. Although relatively uncommon, vascular injuries, such as thoracic outlet syndrome, axillary artery compression, quadrilateral space syndrome, and direct vascular trauma, can afflict these players. These career- and limb-threatening injuries can mimic often seen muscular sprains and strains in their early stages with nonspecific symptoms, such as exertional fatigue, which can delay diagnosis with disastrous sequelae, including thrombus propagation, aneurysm rupture, and ischemia from distal embolization. The goal of this review is to discuss the pathophysiology, diagnosis, and treatment of these injuries to increase awareness of sport-related vascular phenomena among the hand and upper-extremity surgery community because these players typically are seen first in the training room or a hand specialist's office.

Teres Minor Muscle Atrophy: Anatomy, Patterns, and Clinical Manifestations

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Isolated teres minor atrophy has a reported incidence in the literature of 3% to 6.2%.

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There are 2 distinct muscular bundles of the teres minor that have varying degrees of atrophy. Fatty degeneration of the medial-dorsal component exceeds that of the lateral-ventral component in most cases.

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A healthy and intact teres minor muscle is of functional importance in the setting of a complete infraspinatus tear because it becomes the only external rotator of the shoulder joint.

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Clinical and functional outcomes after rotator cuff repair and reverse shoulder arthroplasty for patients with teres minor atrophy in the setting of a rotator cuff tear are still controversial.

Revisiting the Surgical Approaches to Decompression in Quadrilateral Space Syndrome: A Cadaveric Study

Background

Quadrangular space syndrome involves compression of the axillary nerve and posterior circumflex humeral artery. In a few cases, its management requires surgical decompression. The current study reviews the surgical approaches used in the decompression of neurovascular structures and presents our reflections and recommendations.

Methodology

In this study, four human cadavers were used for dissection of the axillae and the scapular region by the senior residents of the Department of Anatomy and Department of Orthopedics. The residents dissected the quadrangular space in the eight upper limbs using anterior and posterior surgical approaches.

Results

To identify the quadrangular space and secure its contents, the posterior approach was recognized as the easier and quicker method by both Anatomy and Orthopedic residents; however, it may result in increased postoperative morbidity. Although the anterior (deltopectoral) approach involves more skill, it reduces postoperative morbidity.

Conclusions

The anterior (deltopectoral) approach with suggested modifications can be an effective method in the surgical decompression of quadrangular space syndrome. The authors suggest more cadaveric studies to provide anatomists and surgeons with the opportunity to practice and evaluate older and newer surgical approaches.

A Review of Upper Extremity Peripheral Nerve Injuries in Throwing Athletes

Peripheral nerve injuries in the upper extremities may be common in throwing athletes as the throwing motion places extreme stress on the dominant arm. The combination of extreme stress along with repetitive microtrauma from throwing uniquely places the throwing athlete at elevated risk of upper extremity peripheral nerve injury. However, because symptoms can be non-specific and frequent co-exist with pathology in the upper extremity, the diagnosis of peripheral nerve injury is often delayed. Diagnosis of peripheral nerve injuries may require a combination of history and physical exam, diagnostic imaging, electrodiagnostic testing, and diagnostic ultrasound guided injections. The primary management should include physical therapy focusing on throwing mechanics and kinetic chain evaluation. However, some athletes require surgical intervention if symptoms do not improve with conservative management. The purpose of this focused narrative review is to highlight upper extremity peripheral neuropathies reported in throwing athletes and to provide an overview of the appropriate clinical diagnosis and management of the throwing athlete with a peripheral nerve injury. This article is protected by copyright. All rights reserved.

Quadrilateral space syndrome

The quadrilateral space is a confined area through which the axillary nerve and posterior circumflex humeral artery (PCHA) travel in the shoulder. Both structures are susceptible to impingement and compression as they travel though this space resulting in a constellation of symptoms known as quadrilateral space syndrome (QSS). Patients may experience paresthesias, loss of motor function, pain and vascular complications. Individuals who perform repetitive overhead arm movements such as elite athletes are at greater risk of developing QSS. The diagnosis can be difficult, but in the setting of clinical suspicion, physical exam and imaging studies can provide specific findings. On MRI, patients may have atrophy of the deltoid or teres minor muscles and angiography may show aneurysm or vascular occlusion of the PCHA. Treatment is initially conservative, with physiotherapy. Surgical decompression is effective in patients with severe or progressive symptoms. Causes of external compression such as fibrous bands, scarring, or other space occupying lesion may be addressed at that time. Neurolysis and aneurysm resection may also be performed. In some cases, emboli from the PCHA can cause ischemia in the involved upper extremity resulting in an acute presentation. Catheter directed therapy such as thrombolysis or thrombectomy may performed emergently in these cases. Though rare, in patients presenting with arm weakness, paresthesia, pain and/or arterial thrombosis in the arm, QSS is an important entity to consider.

Quadrilateral space syndrome induced by a large degenerative osteophyte

A 41-year-old gentleman presented with decreased range of motion. Initial radiographs demonstrated extensive osteoarthritic changes involving the glenohumeral joint with a large inferior oriented osteophyte. Subsequent MRI of the shoulder was obtained which demonstrated isolated fatty atrophy of the teres minor and, to a lesser extent, deltoid muscles. The axillary nerve was visualized entering the quadrilateral space which, although, was severely narrowed secondary to the large osteophyte. The patient's clinical symptoms and MRI findings were consistent with quadrilateral space syndrome. The patient wanted to attempt conservative therapy first; and therefore, subsequently underwent physical therapy with improvement of shoulder strength and range of motion.

Quadrangular Space Syndrome: A Narrative Overview

OBJECTIVE

The purpose of this narrative review of the literature is to provide an overview of quadrangular space syndrome with special attention to its clinical presentation, differential diagnosis, and treatment.

METHODS

A narrative review of the English-language, peer-reviewed literature was performed using the key words "axillary nerve," "quadrangular space," "quadrilateral space," and "posterior humeral circumflex artery." Databases searched were Medline Complete, Cumulative Index to Nursing and Allied Health Literatures, and Index to Chiropractic Literature. The search period was from 1983 through January 2020.

RESULTS

There were 85 articles selected for this review. A summary and overview are provided.

CONCLUSION

Quadrangular space syndrome is an uncommon cause of shoulder pain. Clinicians should consider it as a diagnosis after ruling out more common shoulder conditions and examining other concurrent diseases.

How common is fatty infiltration of the teres minor in patients with shoulder pain? A review of 7,367 consecutive MRI scans

Purpose

The teres minor is particularly important for activities that require external rotation in abduction in the settings of both rotator cuff tears and reverse shoulder arthroplasty. This study sought to assess the incidence of teres minor fatty infiltration in a large cohort of consecutive patients evaluated with shoulder MRI for shoulder pain and to identify all associated pathologies in an effort to determine the various potential etiologies of teres minor involvement.

Methods

A retrospective review of 7,376 non-contrast shoulder MRI studies performed between 2010 and 2015 were specifically evaluated for teres minor fatty infiltration. Studies were reviewed by two fellowship trained musculoskeletal radiologists. Muscle atrophy was graded on a 3-point scale according to Fuchs and Gerber. The remaining rotator cuff tendons and muscles, biceps tendon, labrum, and joint surfaces were assessed on MRI as well.

Results

In this series, 209 (2.8%) shoulders were noted to have fatty infiltration of the teres minor. The rate of isolated fatty infiltration of the teres minor was 0.4%. Concomitant deltoid muscle atrophy was common, and occurred in 68% of the shoulders with fatty infiltration of the teres minor. Tearing of the teres minor tendon was extremely rare.

Conclusion

Fatty infiltration of the teres minor can occur in isolation, be associated with deltoid muscle atrophy only, or occur in the setting of rotator cuff full tears. Thus, fatty infiltration of the teres minor may be related to a neurologic process or disuse. Further long term longitudinal studies are necessary to be elucidate the etiologies.

Level of Evidence

Level IV.

Current concepts review: peripheral neuropathies of the shoulder in the young athlete

Peripheral neuropathies of the shoulder and upper extremity are uncommon injuries that may affect the young athletic population. When present, they can result in significant pain and functional impairment. The cause of peripheral neuropathy in young athletes may be an acute, traumatic injury such as a shoulder dislocation or a direct blow to the shoulder girdle. Alternatively, repetitive overuse with resultant compression or traction of a nerve over time may also result in neuropathy; overhead athletes and throwers may be particularly susceptible to this mechanism of nerve injury. Regardless of etiology, young athletes typically present with activity-related pain, paresthesias, and dysfunction of the affected upper extremity. In addition to physical examination, diagnostic studies such as radiographs and magnetic resonance imaging (MRI) are commonly performed as part of an initial evaluation and electrodiagnostic studies may be used to confirm the diagnosis of peripheral neuropathy. Electrodiagnostic studies may consist of electromyography, which evaluates the electrical activity produced by skeletal muscles, and/or a nerve conduction study, which evaluates a nerve's ability to transmit an electrical signal. Although data are not robust, clinical outcomes for young patients with activity-related peripheral neuropathies of the shoulder are generally good, with most young athletes reporting both symptomatic and functional improvement after treatment.

Quadrilateral space syndrome: The forgotten differential

The quadrilateral space is bounded by the teres minor superiorly, the teres major inferiorly, the long head of the triceps medially and the shaft of the humerus laterally. The axillary nerve and posterior circumflex humeral artery pass through this space to enter the posterior compartment of the upper arm. Quadrilateral space syndrome (QSS) is caused by entrapment of the axillary nerve or its main branches and/or the posterior circumflex humeral artery in the quadrilateral space by internal or external compression. QSS can often be difficult to diagnose, given that patients may present with non-specific symptoms. As such, patients may be misdiagnosed with more common disorders of the shoulder. We report a case of QSS masquerading initially as rotator cuff pathology with positive impingement signs.

Posterior Circumflex Humeral Artery Aneurysm: Case Report and Systematic Literature Review

Posterior circumflex humeral artery (PCHA) aneurysm is a rare condition. It mostly affects young professional sports player and might be career threatening. This is the report of the case of a 28 year old volleyball player presenting with symptoms of right digital ischaemia caused by a PCHA aneurysm. Surgical treatment by resection of the aneurysm without revascularisation was performed. The post-operative course was uneventful and the patient returned to professional competition one month after surgery. A literature review is also presented in an attempt to provide recommendations for PCHA aneurysm diagnosis and management.

Overview of arterial pathology related to repetitive trauma in athletes

BACKGROUND/OBJECTIVE

Sport-related vascular trauma is an important consequence of increased physical activity. Repetitive, high-intensity movements predispose athletes to vascular disease, including arterial pathology, by exerting increased pressure on neurovascular structures. This is an important source of morbidity in an otherwise young and healthy population. Arterial pathology associated with repetitive trauma is often misdiagnosed as musculoskeletal injury. This article increases awareness of sport-related arterial disease by reviewing the symptomatology, investigation, and treatment modalities of this pathology. In addition, prognostic outcomes specific to the athlete are discussed.

RESULTS

Arterial thoracic outlet syndrome and vascular quadrilateral space syndrome are associated with athletes involved in overhead throwing exercises. Sport-related arterial pathology of the lower limb include external iliac artery endofibrosis (EIAE), popliteal artery entrapment syndrome (PAES), and adductor canal syndrome. Vascular stress and kinking secondary to vessel tethering are important contributors to pathology in EIAE. Chronic exertional compartment syndrome must also be considered, presenting with clinical features similar to PAES. In addition, athletes are predisposed to blunt mechanical trauma. Hypothenar hammer syndrome is one such example, contributing to a high burden of morbidity in this population.

CONCLUSIONS

In arterial thoracic outlet syndrome and vascular quadrilateral space syndrome, surgery is advocated in symptomatic individuals, with postoperative outcomes favorable for the athlete. Acute limb ischemia may occur as a result of secondary thrombosis or embolization, often without preceding claudication. PAES and adductor canal syndrome are associated with functional entrapment in the athlete, secondary to muscular hypertrophy. Surgical exploration may be indicated. Poorer outcomes are noted when this process is associated with vascular reconstruction. Surgical treatment of EIAE follows failure of conservative management, with limited data available on postoperative prognosis. Investigations for all these conditions should be targeted based on clinical suspicion. A delay in diagnosis can have severe consequences on return to competition in these high-functioning individuals.

Ultrasonographic measurement of the cross-sectional area of the axillary nerve

INTRODUCTION

The objectives of this study were to determine normal reference values for ultrasonographic measurement of the cross-sectional area (CSA) of the axillary nerve and to standardize the measurement methods.

METHODS

Sixty healthy volunteers were evaluated. Ultrasonography was performed with the shoulder positioned in 100°-120° abduction and 90° external rotation. The CSA of the axillary nerve was measured bilaterally.

RESULTS

The normal CSA of the right axillary nerve was 2.9 ± 1.1 mm² . The side-to-side discrepancy was 22.8% ± 17.8%.

DISCUSSION

These reference values may be helpful for investigating pathologies involving the axillary nerve.

The pattern of idiopathic isolated teres minor atrophy with regard to its two-bundle anatomy

OBJECTIVE

We aimed to analyze the pattern of teres minor atrophy with regard to its two-bundle anatomy and to assess its association with clinical factors.

MATERIALS AND METHODS

Shoulder MRIs performed between January and December 2016 were retrospectively reviewed. Images were evaluated for the presence and pattern of isolated teres minor atrophy. Isolated teres minor atrophy was categorized into complete or partial pattern, and partial pattern was further classified according to the portion of the muscle that was predominantly affected. The medical records were reviewed to identify clinical factors associated with teres minor atrophy.

RESULTS

Seventy-eight shoulders out of 1,264 (6.2%) showed isolated teres minor atrophy; complete pattern in 41.0%, and partial pattern in 59.0%. Most cases of partial pattern had predominant involvement of the medial-dorsal component (82.6%). There was no significant association between teres minor atrophy and previous trauma, shoulder instability, osteoarthritis, and previous operation. The history of shoulder instability was more frequently found in patients with isolated teres minor atrophy (6.4%), compared with the control group (2.6%), although the difference was not statistically significant.

CONCLUSION

Isolated teres minor atrophy may be either complete or partial, and the partial pattern may involve either the medial-dorsal or the lateral-ventral component of the muscle. The imaging findings of partial pattern teres minor atrophy indicate that the two muscle components may have separate innervation.

Axillary Sonography of the Shoulder: An Adjunctive Approach

Sonography of the shoulder is widely used to assess various disorders, including tendinous diseases of the rotator cuff and the long head of the biceps brachii muscle. The shoulder is commonly explored through anterior, superior, and posterior approaches, but the inferior axillary approach is rarely considered in the literature. However, this technique allows the direct visualization of relevant anatomic structures. The aim of this pictorial essay is, first, to technically describe this approach and the normal musculoskeletal sonographic anatomy of the region and, second, to present the sonographic findings of shoulder disorders that may be helpfully explored this technique.

A systematic review on posterior circumflex humeral artery pathology: sports and professions at risk and associated risk factors

INTRODUCTION

Posterior circumflex humeral artery (PCHA) aneurysm formation and thrombosis as overuse injury in the dominant shoulder can result in ischemia of the forearm, hand and digits due to arterial embolisms. Increased awareness among physicians is necessary as PCHA pathology (PCHAP) might be underdiagnosed. Knowledge of sports and professions at risk and risk-factors for obtaining PCHAP is essential for the development of future preventive measures. This study aims to identify sports and professions at risk as well as risk factors for PCHAP.

EVIDENCE ACQUISITION

The databases of MEDLINE, EMBASE, BIOSIS, CINAHL and SPORTDiscus were systematically searched.

EVIDENCE SYNTHESIS

Twenty-seven papers fulfilled the inclusion criteria and described 67 patients with PCHAP involved in seven sports and three professions. The sports (number of cases) were volleyball (41), baseball (13), swimming (1), tennis (3), American football (2), canoeing (1) and yoga (1) (2 unknown). The professions included a baseball coach, a circus trapeze artist and a mechanic. Apart from expert opinions, no studies have identified risk factors for PCHAP. An anatomic variation of the PCHA origin is suggested to be protective for PCHAP.

CONCLUSIONS

PCHAP is reported in seven overhead sports and three professions. No risk factors for PCHAP were identified. An anatomic variant of the PCHA origin was found to be a potential protective factor for PCHAP. Physicians should be cautious for distal embolization as a result of PCHAP in athletes and workers, both adult and adolescent, involved in repetitive powerful overhead movements.

Quadrilateral space syndrome: a review

Quadrilateral space (QS) syndrome (QSS) is a relatively rare condition in which the axillary nerve and the posterior humeral circumflex artery are compressed within the QS. Fibrous bands are most commonly implicated as the cause, with true space-occupying lesions being less common. QSS is characterized by poorly localized shoulder pain and paresthesia over the lateral aspect of the shoulder and arm in a nondermatomal pattern. These symptoms are aggravated by shoulder abduction and external rotation. Point tenderness is typically present over the QS; however, diagnosis on physical examination can be difficult. Pain relief after lidocaine block of the axillary nerve within the QS is a useful finding in the evaluation of patients with suspected QSS. No definitive diagnostic imaging exists, making diagnosis difficult, although radiographs and magnetic resonance imaging are recommended to rule out other pathology. Nonoperative treatment, including nonsteroidal anti-inflammatory drugs, activity modification, and physical therapy, for at least 6 months is recommended before pursuing operative intervention. Small case series have shown that surgical decompression of the QS has good outcomes, with resolution of pain and return to sport.

Quadrilateral Space Syndrome: Diagnosis and Clinical Management

Quadrilateral space syndrome (QSS) is a rare disorder characterized by axillary nerve and posterior humeral circumflex artery (PHCA) compression within the quadrilateral space. Impingement is most frequently due to trauma, fibrous bands, or hypertrophy of one of the muscular borders. Diagnosis can be complicated by the presence of concurrent traumatic injuries, particularly in athletes. Since many other conditions can mimic QSS, it is often a diagnosis of exclusion. Conservative treatment is often first trialed, including physical exercise modification, physical therapy, and therapeutic massage. In patients unrelieved by conservative measures, surgical decompression of the quadrilateral space may be indicated.

Posterior circumflex humeral artery pathology and digital ischemia in elite volleyball: Symptoms, risk factors & suggestions for clinical management

OBJECTIVES

To assess the association between posterior circumflex humeral artery (PCHA) pathology (PCHAP), symptoms and associated risk factors, in elite volleyball players, and to suggest profiles for clinical management and monitoring.

DESIGN

Cross-sectional study.

METHODS

A questionnaire assessed symptoms of digital ischemia (DI) in the dominant hand and risk factors among 278 elite indoor and beach volleyball players of whom 6.1% (17/278) was diagnosed with PCHAP using ultrasound. Odds Ratios (OR) including 95% confidence intervals (95%CI) were calculated using binary logistic regression.

RESULTS

All 278 players completed the questionnaire. Three participants with PCHAP were symptomatic (18%). Ninety-three of 96 symptomatic participants had no PCHAP (OR=0.39; 95% CI 0.13-1.13). Total years playing volleyball (OR 1.14; 95% CI 1.03-1.25) and age (OR 1.17; 95% CI 1.00-1.29) were dose-response related risk factors: a volleyball career of ≥17 years and age of ≥27 years were associated with a 9-fold and 14-fold increased risk of PCHAP, respectively.

CONCLUSIONS

The volleyball career duration and age are dose-response related risk factors for PCHAP among elite indoor and beach volleyball players. DI symptoms are prevalent in a minority of athletes with PCHAP (3/17; 18%). To enable worldwide standardized care for these athletes at risk, four profiles for clinical management and monitoring have been suggested based on questionnaire and ultrasound outcomes.

Understanding the Importance of the Teres Minor for Shoulder Function: Functional Anatomy and Pathology

Although the teres minor is often overlooked in a normal shoulder, it becomes a key component in maintaining shoulder function when other rotator cuff tendons fail. The teres minor maintains a balanced glenohumeral joint and changes from an insignificant to the most significant external rotator in the presence of major rotator cuff pathology. The presence or absence of the teres minor provides prognostic information on the outcomes of reverse total shoulder arthroplasty and tendon transfers. Clinical tests include the Patte test, the Neer dropping sign, the external rotation lag sign, and the Hertel drop sign. Advanced imaging of the teres minor can be used for classification using the Walch system. Understanding the function and pathology surrounding the teres minor is paramount in comprehensive management of the patient with shoulder pathology. Appropriate clinical examination and imaging of the teres minor are important for preoperative stratification and postoperative expectations.

Diagnostic properties of the SPIQuestionnaire to detect Posterior Circumflex Humeral Artery Disease in elite volleyball players: a cross-sectional study

OBJECTIVES

Sports related aneurysmal degeneration and thrombosis of the Posterior Circumflex Humeral Artery (PCHA) has been known to cause symptoms of digital ischemia (DI) in elite volleyball players. Studies have reported symptoms of DI in as much as 28% of the elite indoor volleyball players. The purpose of this study was to determine the diagnostic value of the Shoulder PCHA Pathology and digital Ischemia - Questionnaire (SPI-Q) for detection of sports related PCHA disease using ultrasound data as the standard of reference.

METHODS

The SPI-Q was completed by elite indoor volleyball players from the highest and single highest Dutch volleyball division and by elite beach volleyball players participating in the 2014 Grand Slam Beach Tournament The Hague (GSBTH). Ultrasound assessment of the dominant shoulder was performed on-site using the SPI-US protocol. The SPI-Q sensitivity, specificity, positive - and negative predictive value and positive - and negative likelihood ratios, and the diagnostic odds ratio were calculated for detection of sports related PCHA disease, using ultrasound as the standard of reference.

RESULTS

Two hundred twenty-four elite male indoor volleyball players from the Dutch division were included in this study and 62 elite male and female beach volleyball players participating in the GSBTH: a total of 278 players. Thirty-five percent of the players reported symptoms of DI. The prevalence of PCHA disease was 6.1%. For the SPI-Q we found a sensitivity of 18% (95% CI 4-43), specificity of 64% (95% CI 58-70), positive predictive value of 3% (95% CI 0.7-8.9) and negative predictive value of 92% (95% CI 87-96), positive likelihood ratio of 0.50 (95% CI 0.18-1.40), negative likelihood ratio of 1.28 (95% CI 1.01-1.62) and a diagnostic odds ratio of 0.39 (95% CI 0.11-1.38).

CONCLUSION

The diagnostic value of the SPI-Q to detect PCHA disease in elite volleyball players is poor, which makes it unsuitable as a diagnostic instrument for sports related PCHA disease specifically. However, it can be used to assess all-cause symptoms of DI and raise awareness within athletes and sports physicians, which is important for preventing ischemic complications.

Nerves Around the Shoulder: What the Radiologist Should Know?

Peripheral neuropathies of the shoulder are common and could be related to traumatic injury, shoulder surgery, infection or tumour but usually they result from an entrapment syndrome. Imaging plays an important role to detect the underlying causes, to assess the precise topography and the severity of nerve damage. The key points concerning the imaging of nerve entrapment syndrome are the knowledge of the particular topography of the injured nerve, and the morphology as well signal modifications of the corresponding muscles. Magnetic Resonance Imaging best shows these findings, although Ultrasounds and Computed Tomography sometimes allow the diagnosis of neuropathy.

Nonoperative Management and Novel Imaging for Posterior Circumflex Humeral Artery Injury in Volleyball

We report on a 34-yr-old male elite volleyball player with symptomatic emboli in the spiking hand from a partially thrombosed aneurysm of the posterior circumflex humeral artery (PCHA) in his dominant shoulder. At initial diagnosis and follow-up, a combination of time-resolved and high-resolution steady state contrast-enhanced magnetic resonance angiography (CE-MRA) enabled detailed visualization of: (1) emboli that were not detectable by vascular ultrasound; and (2) the PCHA aneurysm, including compression during abduction and external rotation (ABER provocation). At 15-month follow-up, including forced cessation of volleyball activities over the preceding 9 months, the PCHA aneurysm remained unchanged. Central filling defects in the palmar arch and digital arteries resolved over time and affected arterial vessel segments showed postthrombotic changes. Digital blood pressure values improved substantially and almost normalized during follow-up. In conclusion, this case report is the first to show promising results of nonoperative management for a vascular shoulder overuse injury in a professional volleyball player as an alternative to invasive therapeutic options.

Quadrilateral Space Syndrome With Involvement of the Tendon of the Latissimus Dorsi

Quadrilateral space syndrome (QSS) is the term used to describe axillary nerve palsy due to compression of the axillary nerve and posterior circumflex artery in the quadrilateral space. The precise pathophysiology of QSS is still unclear; hence, a consensus of diagnosis and treatment for QSS has not yet been achieved. The authors present the case of a 17-year-old male baseball player with symptoms of QSS, including right elbow and shoulder joint pain and upper limb numbness while throwing. The symptoms had worsened during baseball. Conservative management for 3 months failed to resolve the symptoms, so surgery was performed. Axillary nerve decompression resulted in functional improvement. The cause of QSS has been previously reported to be fibrous bands, the long head of the triceps, and Bennett lesions. However, the cause of QSS in this case was compression of the axillary nerve between the proximal humerus and the tendinous attachment of the latissimus dorsi. The authors incised a 10- to 15-mm segment of the medial edge of the tendinous insertion of the latissimus dorsi, which resulted in resolution of QSS symptoms. [Orthopedics. 2017; 40(4):e714-e716.].

Vascular Quadrilateral Space Syndrome in 3 Overhead Throwing Athletes: An Underdiagnosed Cause of Digital Ischemia

Vascular quadrilateral space syndrome (vQSS) is an underdiagnosed cause of extremity ischemia, pain, and paresthesia in overhand throwing athletes. The mechanism of vQSS is thought to result from repeated abduction and external rotation of the arm leading to a distraction injury of the posterior circumflex humoral artery (PCHA) as this courses through the quadrilateral space. This trauma may cause dissection and dissecting aneurysm formation. Thrombus from this arterial injury then embolizes down the arm resulting in the symptomatic presentation. Patients were often presented after multiple embolic events, which have resulted in obliteration of digital arteries. Later stages of presentation may include ischemic ulceration and gangrene. We report 3 cases of vQSS in overhand throwing athletes. All 3 underwent surgical correction and have returned to competition. We discuss presentation, diagnosis, imaging findings, management, outcomes, and review of the literature. Prompt recognition of this syndrome is essential to optimal treatment, which includes PCHA ligation and division with or without thrombolytic therapy. Increased awareness of vQSS is needed among coaches and athletic trainers who often identify the symptoms and initiate the treatment. When treated promptly, these athletes return to baseline functional status.

Test-retest reliability and agreement of the SPI-Questionnaire to detect symptoms of digital ischemia in elite volleyball players

The Shoulder posterior circumflex humeral artery Pathology and digital Ischemia - questionnaire (SPI-Q) has been developed to enable periodic surveillance of elite volleyball players, who are at risk for digital ischemia. Prior to implementation, assessing reliability is mandatory. Therefore, the test-retest reliability and agreement of the SPI-Q were evaluated among the population at risk. A questionnaire survey was performed with a 2-week interval among 65 elite male volleyball players assessing symptoms of cold, pale and blue digits in the dominant hand during or after practice or competition using a 4-point Likert scale (never, sometimes, often and always). Kappa (κ) and percentage of agreement (POA) were calculated for individual symptoms, and to distinguish symptomatic and asymptomatic players. For the individual symptoms, κ ranged from "poor" (0.25) to "good" (0.63), and POA ranged from "moderate" (78%) to "good" (97%). To classify symptomatic players, the SPI-Q showed "good" reliability (κ = 0.83; 95%CI 0.69-0.97) and "good" agreement (POA = 92%). The current study has proven the SPI-Q to be reliable for detecting elite male indoor volleyball players with symptoms of digital ischemia.

Ultrasound assessment of the posterior circumflex humeral artery in elite volleyball players: Aneurysm prevalence, anatomy, branching pattern and vessel characteristics

Objectives

To determine the prevalence of posterior circumflex humeral artery (PCHA) aneurysms and vessel characteristics of the PCHA and deep brachial artery (DBA) in elite volleyball players.

Methods

Two-hundred and eighty players underwent standardized ultrasound assessment of the dominant arm by a vascular technologist. Assessment included determination of PCHA aneurysms (defined as segmental vessel dilatation ≥150 %), PCHA and DBA anatomy, branching pattern, vessel course and diameter.

Results

The PCHA and DBA were identified in 100 % and 93 % (260/280) of cases, respectively. The prevalence of PCHA aneurysms was 4.6 % (13/280). All aneurysms were detected in proximal PCHA originating from the axillary artery (AA). The PCHA originated from the AA in 81 % of cases (228/280), and showed a curved course dorsally towards the humeral head in 93 % (211/228). The DBA originated from the AA in 73 % of cases (190/260), and showed a straight course parallel to the AA in 93 % (177/190).

Conclusions

PCHA aneurysm prevalence in elite volleyball players is high and associated with a specific branching type: a PCHA that originates from the axillary artery. Radiologists should have a high index of suspicion for this vascular overuse injury. For the first time vessel characteristics and reference values are described to facilitate ultrasound assessment.

Key Points

• Prevalence of PCHA aneurysms is 4.6 % among elite volleyball players.

• All aneurysms are in proximal PCHA that originates directly from AA.

• Vessel characteristics and reference values are described to facilitate US assessment.

• Mean PCHA and DBA diameters can be used as reference values.

• Radiologists need a high index of suspicion for this vascular overuse injury.

B-Mode Sonographic Assessment of the Posterior Circumflex Humeral Artery: The SPI-US Protocol-A Technical Procedure in 4 Steps

Elite overhead athletes are at risk of vascular injury due to repetitive abduction and external rotation of the dominant arm. The posterior circumflex humeral artery (PCHA) is prone to degeneration, aneurysm formation, and thrombosis in elite volleyball players and baseball pitchers. The prevalence of PCHA-related thromboembolic complications is unknown in this population. However, the prevalence of symptoms associated with digital ischemia is 31% in elite volleyball players. A standardized noninvasive imaging tool will aid in early detection of PCHA injury, prevention of thromboembolic complications, and measurement reproducibility. A standardized vascular sonographic protocol for assessment of the proximal PCHA (SPI-US protocol [Shoulder PCHA Pathology and Digital Ischemia-Ultrasound protocol]) is presented.

Effect of Teres Minor Fatty Infiltration on Rotator Cuff Repair Outcomes

PURPOSE

To observe changes in fatty infiltration (FI) of the teres minor without tear of the teres minor in a postoperative magnetic resonance imaging and to evaluate the influence of FI of the teres minor in the clinical outcomes of rotator cuff repair.

METHODS

Of 816 patients who underwent rotator cuff repair, 51 (6.3%) had FI of the teres minor without tear involvement and 30 cases were available for postoperative magnetic resonance imaging. FI and functional outcome scores were assessed and compared with the control group that had no FI of the teres minor selected by a propensity score matching.

RESULTS

FI of the teres minor was observed in various degrees (grade 1 in 9, grade 2 in 9, grade 3 in 6, and grade 4 in 6). The degree of FI was not related to the amount of tendon involvement of a rotator cuff tear (P = .240). All postoperative functional outcome scores (12.6 ± 1.2 months; range, 11-17), including pain visual analog scale, Simple Shoulder Test, and American Shoulder and Elbow Surgeons Score, significantly improved (all P < .001), and there were no significant differences compared with that of the control group. In most of the cases, FI of the teres minor was unchanged (P = .317).

CONCLUSIONS

FI of the teres minor without tear involvement can be observed in a rotator cuff tear as a possibly incidental finding of unknown clinical significance. Its cause has not been determined, and it appears that FI of the teres minor does not appear to improve, at least at the 1-year follow-up. Nevertheless, the functional outcomes of the repair were successful in our study; therefore, rotator cuff repair can be performed without a great deal of concern in the presence of FI in the teres minor.

LEVEL OF EVIDENCE

Level III, retrospective comparative study.

Reproducibility of the SPI-US protocol for ultrasound diameter measurements of the Posterior Circumflex Humeral Artery and Deep Brachial Artery: an inter-rater reliability study

OBJECTIVES

Elite overhead athletes are at risk of posterior circumflex humeral artery (PCHA) degeneration, aneurysm formation and thrombosis. Identification of the proximal PCHA and the nearby originating deep brachial artery (DBA) can be a challenge, even among experienced sonographers. The aim of this study was to assess the accuracy and precision of a newly designed standardized ultrasound (US) protocol (SPI-US) for assessment of the PCHA and DBA.

METHODS

Two experienced sonographers determined diameters of the PCHA and DBA using the SPI-US protocol. Inter-observer agreement was evaluated using intra-class correlation coefficient (ICC), standard error of measurement (SEM), minimal detectable change (MDC), Bland-Altman (BA) analysis, and variance component (VARCOMP) analysis.

RESULTS

Thirty-three healthy volunteers participated. The ICC for diameter measurement of the PCHA and DBA were 0.70 (95 %CI 0.50-0.83) and 0.60 (95 %CI 0.30-0.80), respectively. The SEM for the PCHA and DBA was 0.32 mm and 0.29 mm and MDC was 0.90 mm and 0.80 mm, respectively. The BA and VARCOMP analyses showed no systematic and only marginal sonographer bias.

CONCLUSIONS

The SPI-US protocol is accurate and precise for PCHA and DBA diameter assessment in cases where they originate from the axillary artery. PCHA and DBA diameter measurements are sonographer-independent using the SPI-US-protocol.

KEY POINTS

• PCHA & DBA diameter assessment is accurate and reliable using the SPI-US protocol • PCHA & DBA diameter measurements are sonographer-independent using the SPI-US protocol • The SPI-US protocol minimal detectable change is 0.90 mm for PCHA diameter measurement • This minimal detectable change enables detection of PCHA aneurysms • First step towards international periodic surveillance of athletes at risk of PCHA-injury.