Cadaveric Study of the Articular Branches of the Shoulder Joint:

Anesthesia for the Patient Undergoing Shoulder Surgery

Shoulder surgery introduces important anesthesia considerations. The interscalene nerve block is considered the gold standard regional anesthetic technique and can serve as the primary anesthetic or can be used for postoperative analgesia. Phrenic nerve blockade is a limitation of the interscalene block and various phrenic-sparing strategies and techniques have been described. Patient positioning is another important anesthetic consideration and can be associated with significant hemodynamic effects and position-related injuries.

A Case of Hospitalization After Pre-operative Interscalene Nerve Block in an Ambulatory Surgery Center

Interscalene nerve block (ISB) is an effective and low-risk local anesthetic (LA) procedure that is commonly employed for shoulder surgery. While phrenic nerve involvement occurs to some degree in every ISB procedure, the incidence of hypoxemia and other clinical signs of diaphragmatic disruption is much lower. This is a case of a 36-year-old female with no underlying respiratory disease who developed hypoxemia requiring a night of observation following an ISB for a rotator cuff repair procedure in an ambulatory surgical center. Her hypoxemia was easily treated with supplemental oxygen and she made a full recovery by the next day. The use of ultrasound guidance, reduced LA volume, less potent medication, sterile fluid for optimal visualization, and extrafascial administration should be considered for all patients receiving an ISB to prevent respiratory complications.

Continuous suprascapular nerve blockade to potentiate intensive rehabilitation for refractory adhesive shoulder capsulitis: a cohort study

PURPOSE

Evaluating the short- and long-term efficacy of a continuous ten day suprascapular nerve block combined with daily multidisciplinary rehabilitation on shoulder range of motion (ROM), pain, and function in patients with refractory adhesive capsulitis (AC).

METHODS

In this retrospective cohort study, patients admitted to a specialized pain clinic for refractory AC for more than 6 months underwent continuous suprascapular nerve blockade for ten days and received 2 hours of physiotherapy and occupational therapy daily. Standardized assessments were performed at baseline, at days three, six, ten, 30, 90, and 180, and included active and passive ROM measurements, the visual analog scale (VAS) for pain and the disabilities of the arm, shoulder and hand (DASH) questionnaire to assess pain, disability, and quality of life. Improvements over time were assessed using ANOVAs.

RESULTS

Thirty-two patients were followed (age: 52 ± 8 years, 25 females, mean symptoms duration of two years). There was a significant improvement in ROM for all amplitudes at day ten (short-term; range: 20-35°, p < 0.001) and at day 180 (long-term; range: 18-47°, p < 0.001). The pain and disability scores significantly reduced by day 180 (mean VAS reduction: 2.6 units, p < 0.001; mean DASH reduction: 9.5 points, p < 0.001).

CONCLUSION

Continuous SSNB combined with intensive multidisciplinary rehabilitation represents an efficient therapeutic option for patients with chronic AC who did not respond to conventional treatments.

Axillary Lymphadenectomy: Safe Dissection Through a Correct Technique

The primary treatment of breast cancer in sentinel-positive ganglia includes axillary lymphatic nodal dissection. The LAD (lymphatic axillary dissection) has decreased in overall numbers but due to the increasing incidence of breast cancer, it is practised on a daily basis, even though there is a myriad of complications such as numbness of the upper limb and chest wall, movement restriction of the upper limb, and chronic pain which appear due to trauma to the nerves which pass through the axilla. However, the utility in the overall survival or DFS (disease-free survival) of the patient is unquestionable.  In our study, through the dissection of cadavers, we exposed the vital structures and the anatomical relations of this region. We aimed to offer a map or technique for the surgeon to follow to decrease the overall morbidity of this procedure.

Phenolysis for Advanced Shoulder Osteoarthritis: A Case Series of a Novel Ultrasound-Guided Approach to Anterior and Posterior Glenohumeral Articular Nerve Branches

INTRODUCTION

The shoulder is one of the joints most affected by osteoarthritis, with a prevalence of almost 20% in adults over 65 years of age. Various treatments have been proposed to control osteoarthritis pain, including radiofrequency, pulsed and thermal, and recently cryoanalgesia. We propose in this series of cases a new approach to analgesic therapy with chemical denervation with phenol.

MATERIALS AND METHOD

Patients who underwent phenolysis for shoulder osteoarthritis at our institutions in Italy and Australia between August 2022 and May 2023 were included. All patients included in our report provided written consent for publication. This chemical neurolysis technique consisted of two injections. First, the anterior shoulder capsule was denervated by a modified deep SHAC (Shoulder Anterior Capsule) approach to cover the anterior terminal articular branches of the axillary nerve, lateral pectoral nerve, and subscapularis nerve. Second, the posterior shoulder capsule was denervated by a posterior glenoid approach to cover the terminal articular branches of the suprascapular nerve (SSN).  Results: We included a total of 11 patients in this case series. Ten of 11 patients were affected by shoulder osteoarthritis, of which three had rotator cuff tendinopathy and three had full-thickness cuff tears. One patient had chronic subluxation of a shoulder prosthesis. After treatment, all patients significantly reduced pain immediately after treatment and, two weeks later, recovered joint movement and improved quality of life. No adverse events or loss of motor function following treatment.

CONCLUSION

We presented a novel chemical approach to shoulder denervation, which was shown to be another effective way of improving pain and function in advanced glenohumeral arthritis.

Low CERVICAL-2 plane block, a proposed regional anesthetic technique for acute cholecystitis

INTRODUCTION

Acute cholecystitis is a painful inflammatory disease of the gallbladder. The Low Cervical-2 Plane Block is a retrolaminar block that targets the C3, C4, and C5 spinal nerves, which provide sensory innervation to the gallbladder, in order to potentially provide analgesia to patients with pain associated with acute cholecystitis.

METHODS

In this brief report, a softly embalmed cadaver was injected with a dye mixture bilaterally.

RESULTS

Subsequent cadaveric dissection revealed spread of the injectate deep to the prevertebral fascia to the C4 lamina on the right side and the C5 lamina on the left side. Also, diffusion of the anesthetic over the ligamenta flava could spread inferiorly and laterally to the spinal nerve roots of C3-C5 and thus potentially target the direct sensory innervation of the gallbladder.

CONCLUSION

The Low Cervical-2 Plane Block is a potentially effective modality for treating intractable pain from acute cholecystitis. However, further cadaveric injections are needed to confirm the exact extent of spread of anesthetic. Clinical application of the Low Cervical-2 Plane Block in patients with acute cholecystitis is needed to establish the efficacy of this theoretical technique.

Cadaveric Analysis of Key Anatomic Structures of Athletic Pubalgia

PURPOSE

This study proposes to establish in-depth inspection of the anatomic structures involved with the pathology of athletic pubalgia in a cadaver model.

METHODS

Eight male fresh frozen cadavers were dissected in a layered fashion. The rectus abdominis (RA) and adductor longus (AL) tendon insertions were isolated to quantify the size of the anatomic footprint and distance from the surrounding anatomy.

RESULTS

The RA insertional footprint was 1.65 cm (SD, 0.18) in width by 1.02 cm (SD, 0.26) in length, and the AL insertional footprint on the underside of the pubis was 1.95 cm (SD, 0.28) in length by 1.23 cm (SD, 0.33) in width. The ilioinguinal nerve was 2.49 cm (SD, 0.36) lateral to the center of the RA footprint and 2.01 cm (SD, 0.37) lateral to the center of the AL footprint. The spermatic cord and the genitofemoral nerve were just lateral to the ilioinguinal nerve and were 2.76 cm (SD, 0.44) and 2.66 cm (SD, 0.46) from the rectus and AL footprints, respectively.

CONCLUSION

Surgeons should be cognizant of these anatomic relations during both initial dissection and tendon repair to optimize repair and avoid iatrogenic injury to critical structures in the anterior pelvis.

Could C3, 4, and 5 Nerve Root Block be a Better Alternative to Interscalene Block Plus Intermediate Cervical Plexus Block for Patients Undergoing Surgery for Midshaft and Medial Clavicle Fractures? A Randomized Controlled Trial

BACKGROUND

Variable innervation of the clavicle is a major challenge in surgery of clavicle fractures with patients under regional anesthesia. An interscalene block (ISB) combined with an intermediate cervical plexus block (ICPB) provides analgesia in clavicle fracture surgery, but this combination does not completely block sensation in the midshaft or medial clavicle. Cervical nerve root block is an alternative to deep cervical plexus block and has recently been used as an analgesic method in the neck and shoulder. Whether it should be used as an alternative for midshaft and medial clavicle fractures is unknown.

QUESTIONS/PURPOSES

In this randomized controlled trial, we compared a C3, 4, and 5 nerve root block to ISB combined with ICPB in surgery of midshaft and medial clavicle fractures in terms of the (1) proportion of patients achieving a sensory block that is sufficient for surgery, (2) onset time and duration of the block, and (3) effectiveness of postoperative analgesia, as measured by pain scores and consumption of analgesics.

METHODS

Between November 2021 and December 2021, we treated 154 patients for clavicle fractures. A total of 122 were potentially eligible, 91 of whom agreed to participate in this study. Twenty-nine patients were excluded because the patients chose general anesthesia or declined to undergo surgery. Ultimately, 62 patients were randomly allocated into the C3, 4, and 5 group or ISB + ICPB group, with 31 patients in each group; there were no dropouts. All patients were analyzed in the group they were randomized to under intention-to-treat principles. The assessor and patients were blinded to randomization throughout the trial. The two groups did not differ in any important ways, including age, gender, BMI, American Society of Anesthesiologists classification, and type of clavicle fracture. The two groups received either an ultrasound-guided C3, 4, and 5 nerve root block with 2, 3, and 5 mL of 0.5% ropivacaine or ultrasound-guided ISB with ICPB with 20 mL of 0.5% ropivacaine. The primary outcome was the proportion of patients in each group with a successful nerveba block who did not receive general anesthesia; this was defined as nerve block success. Secondary outcomes included the onset time and duration of the sensory block, defined as the onset to the moment when the patients felt pain and sought rescue analgesia; pain assessment in terms of the numeric rating scale (NRS) score (range 0 to 10) for pain after nerve block before and during surgery; and the median amount of sufentanil consumed intraoperatively and postoperatively in the recovery room. The dosing of sufentanil was determined by the assessor when the NRS score was 1 to 3 points. If the NRS score was more than 3 points, general anesthesia was administered as a rescue method. Complications after the two inventions such as toxic reaction, dyspnea, hoarseness, pneumothorax, and Horner syndrome were also recorded in this study.

RESULTS

A higher proportion of patients in the C3, 4, and 5 group had a successful nerve block than in the ISB + ICPB group (97% [30 of 31] versus 68% [21 of 31], risk ratio 6 [95% CI 1.5 to 37]; p < 0.01). The median onset time was 2.5 minutes (range 2.0 to 3.0 minutes) in the C3, 4, and 5 group and 12 minutes (range 9 to 16 minutes) in the ISB + ICPB group (difference of medians 10 minutes; p < 0.001). The sensory block duration was 10 ± 2 hours in the C3, 4, and 5 group and 8 ± 2 hours in the ISB + ICPB group (mean difference 2 hours [95% CI 1 to 3 hours]; p < 0.001). The median sufentanil consumption was lower in the C3, 4, 5 group than in the ISB + ICPB (median 5 µg [range 0.0 to 5.0 µg] versus median 0 µg [range 0.0 to 0.0 µg]; difference of medians 5.0 µg; p < 0.001). There were no differences between the two groups regarding NRS scores after nerve blocks and NRS score for incision and periosteum separation, with the minimum clinically important difference set at a 2-point difference (of 10). There were no severe complications in this study.

CONCLUSION

Based on our analysis of the data, a C3, 4, and 5 nerve root block was better than ISB combined with ICPB for surgery to treat medial shaft and medial clavicle fractures. When choosing the anesthesia method, however, the patient's basic physiologic condition and possible complications should be considered.

LEVEL OF EVIDENCE

Level I, therapeutic study.

Educational Curriculum for Peripheral Nerve Stimulation Developed by the North American Neuromodulation Society

BACKGROUND

Peripheral nerve stimulation (PNS) is an effective neuromodulation therapy for chronic neuropathic and nociceptive pain. Although the total number of PNS implantations has increased over the last decade, no curriculum exists to guide training and learning of this therapy. The goal of the North American Neuromodulation Society (NANS) education committee is to develop a series of competency-based curriculums for neuromodulation therapies. The PNS curriculum is the latest part of such series, following the curriculums for spinal cord stimulation and intrathecal drug delivery system.

MATERIALS AND METHODS

A multidisciplinary task force (anesthesiology, physical medicine and rehabilitation, neurosurgery, preventive medicine and public health, and neurology) was created by the educational committee of NANS to develop a PNS curriculum in accordance with the Accreditation Council for Graduate Medical Education (ACGME) milestones. The curriculum was created based on the best available evidence and expert knowledge (from our task force members) of available PNS systems. The final PNS curriculum was approved by the NANS board.

RESULTS

A PNS curriculum was developed by the task force. Milestones included professionalism, practice-based learning, interpersonal communication, medical knowledge, systems-based practice, procedural skills, and patient care. Each milestone was defined into three categories: early learner, advanced learner, and practitioner.

CONCLUSIONS

This manuscript provides a PNS training curriculum developed by a multidisciplinary task force of the NANS educational committee in accordance with the milestones described by ACGME for basic learners, advanced learners, and practitioners. This curriculum will help provide a structured training and evaluation process for obtaining proficiency in PNS treatment(s).

Randomised comparison between superior trunk and costoclavicular blocks for arthroscopic shoulder surgery: A noninferiority study

BACKGROUND

Superior trunk block (STB) provides noninferior analgesia to the interscalene block and reduces the risk of hemidiaphragmatic paralysis (HDP). Recently, supraclavicular spreading has also been shown to occur during costoclavicular block (CCB), presenting as an alternative analgesic technique for shoulder surgery.

OBJECTIVE

The aim of this study was to determine whether there is a difference in postoperative pain scores and HDP incidence between STB and CCB.

DESIGN

Prospective randomised controlled trial.

SETTING

Chungnam National University Hospital in Daejeon from January to July 2021.

PATIENTS

Seventy patients, aged 20 to 70 years with ASA Physical Status classifications I to III and scheduled for elective arthroscopic rotator cuff repair were recruited.

INTERVENTION

Ultrasound-guided STB or CCB was performed with 20 ml 0.5% ropivacaine.

MAIN OUTCOME MEASURES

The primary outcome was the pain score (numeric rating scale, NRS) at 1 h postsurgery. A 1.4 (NRS) noninferiority margin was set a priori . The incidence of HDP, postoperative change of pulmonary function and postoperative opioid use were included as secondary outcomes.

RESULTS

The pain score was higher in the CCB group compared with the STB group at 1 h postoperatively (median difference, 2; 95% confidence interval (CI), 1 to 3; noninferiority was not demonstrated). Two patients in the CCB group received a rescue interscalene block due to severe postoperative pain. The incidence of complete HDP was lower in the CCB group (risk difference, -26%; 95% CI, -6 to -45%; P  < 0.001). The median reduction in forced vital capacity and forced expiratory volume in 1 s were also significantly lower in the CCB group.

CONCLUSION

Although the incidence of HDP was lower, CCB did not show noninferiority in immediate postoperative analgesia compared with STB in arthroscopic shoulder surgery.

CLINICAL TRIAL REGISTRATION

Clinical Trial Registry of Korea (KCT0005822, principal investigator: Boohwi Hong) on 25 January 2021 ( https://cris.nih.go.kr ).

Cryoanalgesia for shoulder pain: a motor-sparing approach to rotator cuff disease

Introduction

Rotator cuff disease is a common cause of musculoskeletal pain and disability, and the management can be challenging. Joint denervation emerges as a new technique, but the literature on shoulder neural ablation procedure is largely limited to pulsed radiofrequency due to the concern of motor impairment. We described a novel motor-sparing approach of cryoablation for the management of shoulder pain based on the recent literature on the innervation of shoulder.

Methods

Four patients with a history of rotator cuff disease refractory to conservative therapy and not amenable to surgery underwent a ultrasound-guided cryoablation of the capsular branches of the shoulder joint after a positive diagnostic injection. The target articular branches were based on the anatomical landmarks described in recent publication. They were the acromial, superior and inferior branches of the suprascapular nerve, the anterior branch of the axillary nerve, the nerve to the subscapularis, which were all located around the superior, posterior and anterior glenoid. The lateral pectoral nerve articular branch was targeted at the coracoclavicular space.

Results

All four patients experienced at least 60% pain relief with improvement in function for 6–12 months following the procedure without any clinical evidence of motor impairment. No adverse effect was observed.

Discussion

Based on the current understanding of the glenohumeral joint articular branches and their relationship to the bony landmark, targeting the articular branches only was feasible and led to good outcomes. Further large prospective cohort study is needed.

Pilot study for treatment of symptomatic shoulder arthritis utilizing cooled radiofrequency ablation: a novel technique

OBJECTIVE

To introduce cooled radiofrequency nerve ablation (C-RFA) as an alternative to managing symptomatically moderate to severe glenohumeral osteoarthritis (OA) in patients who have failed other conservative treatments and who are not surgical candidates or refuse surgery.

MATERIAL AND METHODS

This prospective pilot study includes a total of 12 patients experiencing chronic shoulder pain from moderate to severe glenohumeral OA. Patients underwent anesthetic blocks of the axillary, lateral pectoral, and suprascapular nerves to determine candidacy for C-RFA treatment. Adequate response after anesthetic block was over 50% immediate pain relief. Once patients were deemed candidates, they underwent C-RFA of the three nerves 2-3 weeks later. Treatment response was evaluated using the clinically validated American Shoulder and Elbow Surgeons (ASES) score and visual analog scale (VAS) to assess pain, stiffness, and functional activities of daily living. Follow-up outcome scores were collected up to 6 months after C-RFA procedure.

RESULTS

Twelve patients underwent C-RFA procedure for shoulder OA. VAS scores significantly improved from 8.8 ± 0.6 to 2.2 ± 0.4 6 months after the C-RFA treatment (p < 0.001). Patient's ASES score results significantly improved in total ASES from 17.2 ± 6.6 to 65.7 ± 5.9 (p < 0.0005). No major complications arose. No patients received re-treatment or underwent shoulder arthroplasty.

CONCLUSION

Image-guided axillary, lateral pectoral, and suprascapular nerve C-RFA has minimal complications and is a promising alternative to treat chronic shoulder pain and stiffness from glenohumeral arthritis.

The painful shoulder arthroplasty: appropriate work-up and review of interventional pain treatments

Shoulder arthroplasty is a successful surgical procedure for several conditions when patients become refractory to conservative management modalities. Unfortunately, some patients experience persistent chronic pain after shoulder arthroplasty. These individuals should undergo a comprehensive evaluation by an orthopedic surgeon to determine whether structural pathology is responsible for the pain and to decide whether reoperation is indicated. At times, a surgical solution does not exist. In these circumstances, a thorough and specific plan for the management of persistent chronic pain should be developed and instituted. In this article, we review common reasons for persistent pain after shoulder arthroplasty and outline the evaluation of the painful shoulder arthroplasty. We then provide a thorough review of interventional pain management strategies. Finally, we hypothesize developments in our field that might provide better outcomes in the future for patients suffering with chronic intractable pain after shoulder arthroplasty.

Clinical implications of the distinct anatomy and innervation of the long head biceps tendon

The proximal long head of the biceps tendon (LHBT) has been recognized as a well-known cause of anterior shoulder pain. Previous studies have identified a heterogeneous distribution of nerve fibers in the tendon, with a higher abundance of fibers in the proximal and distal thirds of the tendon. This suggests that the proximal portion of the long head biceps tendon may have a different source of innervation than the distal portion. The purpose of this study was to review the innervation of the superior shoulder and identify the proximal source of sensory innervation of the LHBT. The relevant hypothesis was that the suprascapular nerve (SSN) was the proximal source of sensory innervation to the LHBT. Gross and microdissection of eight fresh human cadaver shoulders were performed, with a focus on the distal articular branches of suprascapular nerve (SSN). Utilizing 3.5× magnification loupes, the medial subacromial branch (MSAb), lateral subacromial branch (LSAb), and posterior glenohumeral branch (PGHb) were identified and followed distally to their terminal branches. In all specimens, terminal branches of the lateral subacromial branch supplied the proximal LHBT and the superior labrum. Terminal branches of the posterior glenohumeral branch supplied the posterosuperior labrum and, to a lesser extent, the labral attachment of the LHBT. These findings confirm branches of the suprascapular nerve as the proximal source of sensory innervation to the LHBT. Identification of the suprascapular nerve as a source of proximal innervation of the LHBT may influence clinical decisions related to nonsurgical and surgical intervention, nerve blocks, and nerve ablation procedures.

CT-Guided Cooled Radiofrequency Denervation for Chronic Arthritis Pain of the Hip and Shoulder

The paradigm in the treatment of arthritis pain is shifting for previously open surgical denervations of the hip and shoulder, as it already has for the geniculate nerves in knee arthritis. Interventional radiology is poised to contribute to this space with the use of CT guidance to provide safe, fast, and effective targeting of the target nerves for unequivocal diagnostic nerve block and definitive cooled radiofrequency denervation. The authors provide the background of which nerves are targeted for hip and shoulder denervation and the normal CT appearance of these blocks.

Low volume proximal suprascapular nerve block after arthroscopic shoulder surgery - A randomised, controlled trial

BACKGROUND

A proximal suprascapular nerve block has been suggested as an alternative to an interscalene brachial plexus block after arthroscopic shoulder surgery. The aim of this randomised controlled trial was to compare the analgesic and opioid-sparing effect of a low volume proximal suprascapular nerve block with placebo in patients with moderate-to-severe pain after arthroscopic shoulder surgery.

METHODS

Patients with a VAS score equal to or above 50 during the first postoperative hour after planned arthroscopic shoulder surgery were included in the study. They were randomised to an ultrasound-guided proximal suprascapular nerve block with either 5 ml ropivacaine 7.5 mg/ml or 5 ml isotonic NaCl. Primary outcome was change in VAS score at rest from baseline to 30 min after the block procedure (T30). Secondary outcomes included total morphine consumption from 0-6 h after block procedure.

RESULTS

There was a significant difference in mean VAS reductions at T30 between the two groups favouring the ropivacaine group (-50.2 vs -26.8, p < .001). Total intravenous morphine consumption from 0-6 h after block procedure was significantly lower in the ropivacaine group compared to the placebo group (8.5 mg vs 18.5 mg, p < .01).

CONCLUSION

In this study, a proximal suprascapular nerve block with only 5 ml ropivacaine resulted in a substantial pain reduction and opioid-sparing effect in patients with VAS of 50 or more after arthroscopic shoulder surgery.

Anesthesia for the Patient Undergoing Shoulder Surgery

Shoulder surgery introduces important anesthesia considerations. The interscalene nerve block is considered the gold standard regional anesthetic technique and can serve as the primary anesthetic or can be used for postoperative analgesia. Phrenic nerve blockade is a limitation of the interscalene block and various phrenic-sparing strategies and techniques have been described. Patient positioning is another important anesthetic consideration and can be associated with significant hemodynamic effects and position-related injuries.

Cooled Radiofrequency Ablation for Chronic Joint Pain Secondary to Hip and Shoulder Osteoarthritis

Osteoarthritis (OA) of the shoulder and hip is a leading cause of physical disability and mental distress. Traditional nonsurgical management alone is often unable to completely address the associated chronic joint pain. Moreover, a large number of patients are not eligible for joint replacement surgery owing to comorbidities or cost. Radiofrequency ablation (RFA) of articular sensory nerve fibers can disrupt the transmission of nociceptive signals by neurolysis, thereby providing long-term pain relief. A subtype of RFA, cooled RFA (CRFA), utilizes internally cooled electrodes to generate larger ablative zones compared with standard RFA techniques. Given the complex variable innervation of large joints such as the glenohumeral and hip joints, a larger ablative treatment zone, such as that provided by CRFA, is desired to capture a greater number of afferent nociceptive fibers. The suprascapular, axillary, and lateral pectoral nerve articular sensory branches are targeted during CRFA of the glenohumeral joint. The obturator and femoral nerve articular sensory branches are targeted during CRFA of the hip. CRFA is a promising tool in the interventionalist's arsenal for management of OA-related pain and symptoms, particularly in patients who cannot undergo, have long wait times until, or have persistent pain following joint replacement surgery. An invited commentary by Tomasian is available online. ^©RSNA, 2022.

Review of Extraosseous Applications of Thermal Ablation in the Treatment of Moderate to Severe Large Joint Osteoarthritis

Osteoarthritis (OA) is the most common joint disease worldwide, leading to significant pain, restricted range of motion, and disability. A gap exists between short- and long-term symptom-relieving therapies. Although arthroplasty is an effective treatment for symptomatic end-stage disease, most patients ultimately do not receive a joint replacement due to suboptimal surgical qualifications, comorbidities, or an aversion to surgery. The lack of additional treatment options in this setting makes opioid agonists a commonly used pharmacologic agent, contributing to the addiction epidemic that greatly afflicts our communities. Cooled radiofrequency ablation (CRFA) has arisen as a treatment modality in the setting of moderate to severe OA among patients refractory to conservative management, generally showing greater efficacy compared with other existing strategies. This review focuses on the benefits of CRFA and its technical feasibility as a management option among patients experiencing debilitating large joint OA with limited clinical options.

Overview of Innervation of Shoulder and Acromioclavicular Joints

Detailed understanding of the course and location of articular nerves supplying the shoulder joint is paramount to the successful utilization of image-guided radiofrequency ablation to manage chronic shoulder pain. In this article, the origin, course, and relationship to anatomic landmarks of articular nerves supplying the shoulder and acromioclavicular joints are discussed. The shoulder joint capsule was consistently reported to receive innervation from multiple sources including the suprascapular, axillary, subscapular, and lateral pectoral nerves. The acromioclavicular joint received innervation from suprascapular and lateral pectoral nerves. The consistent relationship of articular branches to anatomic landmarks provides the basis for specific image-guided targeting.

Shoulder Ablation Approaches

The shoulder is structurally and functionally complex. Shoulder pain may be refractory to conventional treatments, such as physical therapy, pharmacotherapy, and corticosteroid injections. In such cases, radiofrequency ablation may serve as an alternative treatment plan. Current literature has demonstrated 4 target nerves for ablative therapy: the suprascapular nerve, axillary nerve, lateral pectoral nerve, and subscapular nerve. Special caution is needed when targeting these nerves in order to avoid motor denervation. This article summarizes the current evidence for radiofrequency ablation as a useful treatment option for chronic shoulder pain as well as the described techniques for performing this promising procedure.

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

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

Putting Our Shoulder to the Wheel: Current Understanding and Gaps in Nerve Ablation for Chronic Shoulder Pain

Shoulder pain is prevalent, burdensome, and functionally limiting, with diverse pathology and associated treatments. This narrative review provides a summary of relevant neuroanatomy, proposed ablation targets, safety and efficacy concerns for ablation targets, and current research gaps. Radiofrequency ablation (RFA) of peripheral sensory nerves is a well-established treatment for chronic joint and spine pain, but it is relatively nascent for shoulder pain. Cadaveric studies demonstrate the shoulder joint is innervated by articular branches of the suprascapular nerve, axillary nerve, lateral pectoral nerve, and upper and lower subscapular nerves. Shoulder articular branch RFA appears to be a safe and effective treatment for chronic shoulder pain, but there are currently no widely accepted protocols for ablation targets. There are also no randomized controlled trials (RCT) assessing safety and efficacy of proposed targets or the prognostic value of articular blocks. Future research studies should prioritize categorical data, use appropriate functional measures as primary endpoints, and would ideally include a large-scale RCT.

Quantitative Ultrasonographic Analysis of Changes of the Suprascapular Nerve in the Aging Population With Shoulder Pain

Background

Older people are vulnerable to painful shoulder syndromes, the majority of which are derived from degenerative rotator cuff pathologies. The suprascapular nerve (SSN) is closely related to the rotator cuff complex, and its role in shoulder pain has recently been highlighted. This study aimed to explore the differences in SSN among older people with and without shoulder pain, and to investigate the potential factors influencing the nerve size using ultrasound (US) imaging.

Methods

Participants aged ≥60 years were enrolled in the study. A systematic and bilateral US examination of the rotator cuff tendons was performed. The SSN was examined from its origin in the brachial plexus to the spinoglenoid notch of the infraspinatus fossa. The association between the nerve’s cross-sectional area (CSA) and rotator cuff lesions was analyzed using the generalized estimation equation.

Results

Among the 94 participants, 45 (with bilaterally asymptomatic shoulders) were classified into the control group, whereas 49 (with at least one-sided shoulder pain) were classified into the group with shoulder pain. The average CSAs of the SSN at the level of the brachial plexus, supraspinatus fossa, and infraspinatus fossa were comparable between the patients in the control group and those with shoulder pain. There was a higher prevalence of rotator cuff lesions and enlarged distal SSNs in the painful shoulders than in the asymptomatic shoulders of patients with unilateral involvement. A full-thickness tear of the supraspinatus tendon was associated with swelling of the SSN in the supraspinatus fossa (β coefficient = 4.068 mm², p < 0.001).

Conclusion

In the older population, full-thickness tears of the supraspinatus tendon are independently associated with enlargement of the distal SSN. In cases with large rotator cuff tendon tears with poor response to conservative treatments, possible SSN entrapment should be considered and managed accordingly.

Diagnostic block and radiofrequency ablation of the acromial branches of the lateral pectoral and suprascapular nerves for shoulder pain: a 3D cadaveric study

BACKGROUND AND OBJECTIVES

Acromial branches of the lateral pectoral and suprascapular nerves have been proposed as targets for diagnostic block and radiofrequency ablation to treat superior shoulder pain; however, the nerve capture rates of these procedures have not been investigated. The objectives of this study were to use dissection and 3D modeling technology to determine the course of these acromial branches, relative to anatomical landmarks, and to evaluate nerve capture rates using ultrasound-guided dye injection and lesion simulation.

METHODS

Ultrasound-guided dye injections, targeting the superior surface of coracoid process and floor of supraspinous fossa, were performed (n=5). Furthermore, needles targeting the superior and posterior surfaces of the coracoid process were placed under ultrasound guidance to simulate needle electrode position (n=5). Specimens were dissected, digitized, and modeled to determine capture rates of acromial branches of lateral pectoral and suprascapular nerves.

RESULTS

The course of acromial branches of lateral pectoral and suprascapular nerves were documented. Dye spread capture rates: acromial branches of lateral pectoral and suprascapular nerves were captured in all specimens. Lesion simulation capture rates: (1) when targeting superior surface of coracoid process, the entire acromial branch of lateral pectoral nerve was captured in all specimens and (2) when targeting posterior surface of coracoid process, the acromioclavicular and bursal branches of acromial branch of suprascapular nerve were captured in all specimens; coracoclavicular branch was captured in 3/5 specimens.

CONCLUSIONS

This study supports the anatomical feasibility of ultrasound-guided targeting of the acromial branches of lateral pectoral and suprascapular nerves. Further clinical investigation is required.

Sensory innervation of the human shoulder joint: the three bridges to break

BACKGROUND

Painful shoulders create a substantial socioeconomic burden and significant diagnostic challenge for shoulder surgeons. Consensus with respect to the anatomic location of sensory nerve branches is lacking. The aim of this literature review was to establish consensus with respect to the anatomic features of the articular branches (ABs) (1) innervating the shoulder joint and (2) the distribution of sensory receptors about its capsule and bursae.

MATERIALS AND METHODS

Four electronic databases were queried, between January 1945 and June 2019. Thirty original articles providing a detailed description of the distribution of sensory receptors about the shoulder joint capsule (13) and its ABs (22) were reviewed.

RESULTS

The suprascapular, lateral pectoral, axillary, and lower subscapular nerves were found to provide ABs to the shoulder joint. The highest density of nociceptors was found in the subacromial bursa. The highest density of mechanoreceptors was identified within the insertion of the glenohumeral ligaments. The most frequently identified innervation pattern comprised 3 nerve bridges (consisting of ABs from suprascapular, axillary, and lateral pectoral nerves) connecting the trigger and the identified pain generator areas rich in nociceptors.

CONCLUSION

Current literature supports the presence of a common sensory innervation pattern for the human shoulder joint. Anatomic studies have demonstrated that the most common parent nerves supplying ABs to the shoulder joint are the suprascapular, lateral pectoral, and axillary nerves. Further studies are needed to assess both the safety and efficacy of selective denervation of the painful shoulders, while limiting the loss of proprioceptive function.

Effectiveness of new nerve blocks method on the articular branches of the suprascapular and subscapular nerves to treat shoulder pain

To evaluate the effectiveness and safety of performing nerve blocks on the articular branches of the suprascapular and subscapular nerves for the treatment of shoulder pain caused by various pathologies.Fifty-two patients with shoulder pain were included in this study. Suprascapular and subscapular nerve blocks were performed with 2.5 mL anesthetic solution (2 mL of 0.5% bupivacaine and 0.5 mL of 2 mg/mL dexamethasone). The subjects were evaluated before the procedure and 1, 3, and 6 months afterward by means of the numeric rating scale and the shoulder pain and disability index. A post-injection pain reduction of >50% and <50% was considered a positive and negative response to the blocks, respectively.After nerve blocks, the mean numeric rating scale and shoulder pain and disability index scores were significantly reduced from pre-injection values, and this effect persisted for 6 months after injection. The positive and negative response groups consisted of 31 (60%) and 21 (40%) patients, respectively. The positive response group showed significantly better outcomes on the numeric rating scale and shoulder pain and disability index compared with the negative response group. No patients reported adverse effects either during or after the procedure.Performing nerve blocks on the articular branches of the suprascapular and subscapular nerves resulted in positive outcomes for shoulder pain patients. Regardless of shoulder pathology, this new injection method can be safely used in shoulder pain patients.

Adaptation of an Ultrasound-Guided Technique for Pulsed Radiofrequency on Axillary and Suprascapular Nerves in the Treatment of Shoulder Pain

BACKGROUND

It has been estimated that 20% of the general population will suffer shoulder pain throughout their lives, with a prevalence that can reach up to 50%. The suprascapular nerve (SSN) provides sensation for the posterior and superior regions of the glenohumeral joint, whereas the anterior and inferior zones and the skin are innervated mostly by the axillary nerve. Pulsed radiofrequency on the SSN has been proposed as a therapeutic option in chronic shoulder pain. Axillary nerve block has been proposed in the context of surgical analgesia as an adjuvant to SSN block.

INTERVENTIONS

Ultrasound (US)-guided techniques target the nerve selectively, minimizing patients' and physicians' exposure to harmful radiation while increasing success rates by better needle placement. We perform both US-guided techniques with the patient in a lateral decubitus position with the affected shoulder on the upper side.

OBJECTIVE

The aim of this report is to describe the adaptation of a US-guided technique that targets both the suprascapular and axillary nerves for the treatment of painful shoulder syndrome. The simultaneous pulsed radiofrequency on the suprascapular and axillary nerves for the treatment of the chronic condition of shoulder pain has been scarcely studied, with very few references in the literature.

CONCLUSIONS

By adapting an approach developed in acute pain management, we can safely deliver pulsed radiofrequency to the suprascapular and axillary nerves for the treatment of shoulder pain.

Subomohyoid Anterior Suprascapular Block versus Interscalene Block for Arthroscopic Shoulder Surgery

Background

Interscalene brachial plexus block, the pain relief standard for shoulder surgery, is an invasive technique associated with important complications. The subomohyoid anterior suprascapular block is a potential alternative, but evidence of its comparative analgesic effect is sparse. The authors tested the hypothesis that anterior suprascapular block is noninferior to interscalene block for improving pain control after shoulder surgery. As a secondary objective, the authors evaluated the success of superior trunk (C5–C6 dermatomes) block with suprascapular block.

Methods

In this multicenter double-blind noninferiority randomized trial, 140 patients undergoing shoulder surgery were randomized to either interscalene or anterior suprascapular block with 15 ml of ropivacaine 0.5% and epinephrine. The primary outcome was area under the curve of postoperative visual analog scale pain scores during the first 24 h postoperatively. The 90% CI for the difference (interscalene-suprascapular) was compared against a –4.4-U noninferiority margin. Secondary outcomes included presence of superior trunk blockade, pain scores at individual time points, opioid consumption, time to first analgesic request, opioid-related side-effects, and quality of recovery.

Results

A total of 136 patients were included in the analysis. The mean difference (90% CI) in area under the curve of pain scores for the (interscalene-suprascapular) comparison was –0.3 U (–0.8 to 0.12), exceeding the noninferiority margin of –4.4 U and demonstrating noninferiority of suprascapular block. The risk ratio (95% CI) of combined superior trunk (C5–C6 dermatomes) blockade was 0.98 (0.92 to 1.01), excluding any meaningful difference in superior trunk block success rates between the two groups. When differences in other analgesic outcomes existed, they were not clinically important.

Conclusions

The suprascapular block was noninferior to interscalene block with respect to improvement of postoperative pain control, and also for blockade of the superior trunk. These findings suggest that the suprascapular block consistently blocks the superior trunk and qualify it as an effective interscalene block alternative.

Editor’s Perspective

What We Already Know about This Topic

What This Article Tells Us That Is New

Evaluation of suprascapular nerve radiofrequency ablation protocols: 3D cadaveric needle placement study

BACKGROUND AND OBJECTIVES

Image-guided intervention of the suprascapular nerve is a reported treatment to manage chronic shoulder joint pain. The suprascapular nerve is conventionally targeted at the suprascapular notch; however, targeting of its branches, the medial and lateral trunks, which are given off just posterior to the notch has not been considered. Since the lateral trunk supplies the posterior supraspinatus and articular branches to the glenohumeral joint capsule, while the medial trunk provides motor innervation to the anterior region, it may be possible to preserve some supraspinatus activation if the medial trunk is spared. The main objective was to investigate whether midpoint between suprascapular and spinoglenoid notches is the optimal target to capture articular branches of lateral trunk while sparing medial trunk.

METHODS

In 10 specimens, using ultrasound guidance, one 17 G needle was placed at the suprascapular notch and a second at midpoint between suprascapular and spinoglenoid notches. The trunks and needles were exposed in the supraspinous fossa, digitized and modeled in 3D. Lesion volumes were added to the models to asses medial and lateral trunk capture rates. Mean distance of needle tips to origin of medial trunk was compared.

RESULTS

Conventional notch technique captured both lateral and medial trunks, whereas a midpoint technique captured only lateral trunk. Mean distance of needles from the origin of medial trunk was 5.10±1.41 mm (notch technique) and 14.99±5.53 mm (midpoint technique).

CONCLUSIONS

The findings suggest that the midpoint technique could spare medial trunk of suprascapular nerve, while capturing lateral trunk and articular branches. Further clinical investigation is required.

Sensory innervation of the subacromial bursa by the distal suprascapular nerve: a new description of its anatomic distribution

BACKGROUND

Sensory innervation to the shoulder provided by the distal suprascapular nerve (dSSN) remains the subject of debate. The purpose of this study was to establish consensus with respect to the anatomic features of the sensory branches of the dSSN. The relevant hypothesis was that the dSSN would give off 3 sensory branches providing innervation to the posterior glenohumeral (PGH) capsule, the subacromial bursa, in addition to the coracoclavicular and acromioclavicular ligaments.

METHODS

The division, course, and distribution of the sensory branches that originated from the dSSN and innervated structures around the shoulder joint were examined macroscopically by dissecting 37 shoulders of 19 fresh-frozen cadavers aged of 83.0 years (range, 74-98 years).

RESULTS

The 37 dSSN provided 1 medial subacromial branch (MSAb), 1 lateral subacromial branch (LSAb), and 1 PGH branch (PGHb) to the shoulder joint. This arrangement allowed for bipolar-MSAb and LSAb-innervation of the subacromial bursa, acromioclavicular (MSAb and LSAb) and coracoclavicular (MSAb) ligaments, as well as the PGH capsule (PGHb).

CONCLUSIONS

The dSSN provided 2 subacromial branches and 1 PGHb to the shoulder joint. This arrangement allowed for bipolar-MSAb and LSAb-innervation of the subacromial bursa, acromioclavicular and coracoclavicular ligaments, as well as the PGH capsule.

Ultrasound-Guided Versus Landmark-Based Approach to the Distal Suprascapular Nerve Block: A Comparative Cadaveric Study

PURPOSE

To compare the accuracy of distal suprascapular nerve (dSSN) blockade performed with the use of ultrasound-guided regional anesthesia (USRA) versus with a landmark-based approach (LBA). A secondary aim was to describe the anatomic features of the sensory branches of the dSSN.

METHODS

USRA and LBA were performed in 15 shoulders each from 15 cadavers (total of 30 shoulders). Then, 10 mL of methylene blue‒infused ropivacaine 0.75% was injected into the dSSN. Simultaneously, 2.5 mL of red latex solution was injected to identify the position of the needle tip. The division and distribution of the sensory branches originating from the SSN were described.

RESULTS

The tip of the needle was identified at 1.3 cm (range, 0-5.2 cm) and 1.5 cm (range, 0-4.5 cm) with USRA and the LBA, respectively (P = .90). Staining diffused past the origin of the most proximal sensory branch in 27 cases. The most proximal sensory branch arose 2.5 cm from the suprascapular notch. Among the 3 failures that occurred in the USRA group, the sensory branches also failed to be marked. All 30 dSSNs gave off 3 sensory branches, which innervated the posterior glenohumeral capsule, the subacromial bursa, and the coracoclavicular and acromioclavicular ligaments.

CONCLUSIONS

An LBA is as reliable and accurate as US guidance for anesthetic blockade of the dSSN. Marking of the suprascapular nerve must be proximal to the suprascapular notch to involve the 3 sensory branches in the anesthetic blockade.

CLINICAL RELEVANCE

The present study demonstrates that a landmark-based approach to anesthetic blockade of the distal suprascapular nerve is accurate and can be performed by orthopaedic surgeons lacking experience in ultrasound-guided anesthetic techniques.

Ultrasound-Guided Proximal and Distal Suprascapular Nerve Blocks: A Comparative Cadaveric Study

Objectives

The primary aim of our study was to evaluate and compare the accuracy of ultrasound (US)-guided distal suprascapular nerve (dSSN) and proximal SSN (pSSN) blocks. Secondary aims were to compare the phrenic nerve involvement between groups and to describe the anatomical features of the sensory branches of the dSSN.

Methods

pSSN and dSSN blocks were performed in 14 cadavers (28 shoulders). Ten mL of 0.2% ropivacaine colored with methylene blue was injected under US guidance. Accuracy was determined using SSN staining and the distance between predefined anatomical landmarks and the targeted SSN. The phrenic nerve (PN) was judged to be colored or not. The distribution of the sensory branches that originate from the 14 dSSNs is described. Quantitative data are expressed as median (range).

Results

The pSSN was dyed more frequently than the dSSN (13 vs 11, P = 0.59). The targeted SSN was close to the suprascapular notch (1.3 [0–5.2] cm) and the origin of the SSN (1.4 [0.2–4.5] cm) for dSSN and pSSN blocks, respectively (P = 0.62). For dSSN blocks, the most frequent injection site was the supraspinous fossa. Three PNs were marked in pSSN blocks, compared with none in dSSN blocks (P = 0.22). Three sensory branches were identified for all 14 dSSNs: the medial subacromial branch, the lateral subacromial branch, and the posterior glenohumeral branch.

Conclusions

US-guided pSSN and dSSN blocks can be realized with accuracy. A distal approach to the SSN could be an alternative to interscalene brachial plexus block for the management of postoperative pain after shoulder surgery in high–respiratory risk patients.

Peripheral nerve catheters: A critical review of the efficacy

Continuous peripheral nerve blocks are commonly used for postoperative analgesia after surgery. However, catheter failure may occur due to either primary (incorrect insertion) or secondary reasons (displacement, obstruction, disconnection). Catheter failure results in unanticipated pain, need for opioid use, and risk of readmission or delay in hospital discharge. This review aimed to assess definition and frequency of catheter failure, and discuss the alternatives to prolong duration of single-shot nerve blocks. A literature search was performed on peripheral catheters reporting failure as the main outcome measure. Thirty-three studies met the selection criteria, comprising 2711 catheters. Literature review suggests that peripheral nerve catheters have clinically significant failure rate when the assessment is performed using an objective (imaging) method. Subjective methods of assessment (without imaging) may underestimate the incidence of catheter failure.

Quantitative analysis of the distal, lateral, and posterior articular branches of the axillary nerve to the shoulder: implications for intervention

INTRODUCTION

The terminal sensory branches innervating the shoulder joint are potential therapeutic targets for the treatment of shoulder pain. This cadaveric study investigated in detail the anatomic pathway of the posterior terminal sensory branch of the axillary nerve (AN) and its relationship to nearby anatomic structures for applications, such as nerve block or ablation of the shoulder joint.

METHODS

For this study, nine shoulders were dissected. Following dissection, methylene blue was used to stain the pathway of the terminal sensory branches of the AN to provide a visual relationship to the nearby bony structures. A transparent grid was overlaid on the humeral head to provide further detailed information regarding the innervation to the shoulder joint.

RESULTS

Eight of the nine shoulders displayed terminal sensory branches of the AN. The terminal sensory branches of the AN innervated the posterolateral head of the humerus and shoulder capsule and were deep and distal to the motor branches innervating the deltoid muscle and teres minor muscle. All terminal branches dissected innervated the shoulder capsule at the posteroinferior-lateral aspect of the greater tuberosity of the humerus. All specimens displayed innervation to the shoulder joint in the lateral most 25% and inferior most 37.5% before methylene blue staining.

CONCLUSION

The terminal sensory branches of the AN consistently innervate the inferior and lateral aspects of the posterior humeral head and shoulder capsule. These nerves are easily accessible and would provide a practical target for nerve block or ablation to relieve shoulder pain without compromising motor integrity.

Distal suprascapular nerve block-do it yourself: cadaveric feasibility study

BACKGROUND

A bone landmark-based approach (LBA) to the distal suprascapular nerve (dSSN) block is an attractive "low-tech" method available to physicians with no advanced training in regional anesthesia or ultrasound guidance. The primary aim of this study was to validate the feasibility of an LBA to blockade of the dSSN by orthopedic surgeons using anatomic analysis. The secondary aim was to describe the anatomic features of the sensory branches of the dSSN.

MATERIALS AND METHODS

An LBA was performed in 15 cadaver shoulders by an orthopedic resident. Then, 10 mL of methylene blue-infused 0.75% ropivacaine was injected around the dSSN; 2.5mL of red latex solution was also injected to identify the position of the needle tip. The division and distribution of the sensory branches that originate from the suprascapular nerve were described.

RESULTS

The median distance between the dSSN and the site of injection was 1.5 cm (0-4.5 cm). The most common injection site was at the proximal third of the scapular neck (n = 8). Fifteen dSSNs were stained proximal to the origin of the most proximal sensory branch. All 15 dSSNs gave off 3 sensory branches that innervated the posterior glenohumeral capsule, the subacromial bursa, and the coracoclavicular and acromioclavicular ligaments.

CONCLUSIONS

An LBA for anesthetic blockade of the dSSN by an orthopedic surgeon is a simple, reliable, and accurate method. Injection close to the suprascapular notch is recommended to involve the dSSN proximally and its 3 sensory branches.

Ultrasonography-guided anterior approach for axillary nerve blockade: An anatomical study

Combined ultrasound (US)-guided blockade of the suprascapular and axillary nerves (ANs) has been proposed as an alternative to interscalene blockade for pain control in shoulder joint pathology or postsurgical care. This technique could help avoid respiratory complications and/or almost total upper limb palsy. Nowadays, the AN blockade is mostly performed using an in-plane caudal-to-cephalic approach from the posterior surface of the shoulder, reaching the nerve immediately after it exits the neurovascular quadrangular space (part of the spatium axillare). Despite precluding most respiratory complications, this approach has not made postsurgical pain relief any better than an interscalene blockade, probably because articular branches of the AN are not blocked.Cephalic-to-caudal methylene blue injections were placed in the first segment of the AN of six Thiel-embalmed cadavers using an US-guided anterior approach in order to compare the distribution with that produced by a posterior approach to the contralateral AN in the same cadaver. Another 21 formalin-fixed cadavers were bilaterally dissected to identify the articular branches of the AN.We found a good spread of the dye on the AN and a constant relationship of this nerve with the subscapularis muscle. The dye reached the musculocutaneous nerve, which also contributes to shoulder joint innervation. We describe the anatomical landmarks for an ultrasonography-guided anterior AN blockade and hypothesize that this anterior approach will provide better pain control than the posterior approach owing to complete blocking of the joint nerve. Clin. Anat. 33:488-499, 2020. © 2019 Wiley Periodicals, Inc.

Anatomical study of the innervation of glenohumeral and acromioclavicular joint capsules: implications for image-guided intervention

BACKGROUND AND OBJECTIVES

In 2011, chronic shoulder joint pain was reported by 18.7 million Americans. Image-guided radiofrequency ablation has emerged as an alternative intervention to manage chronic shoulder joint pain. To optimize the effectiveness of shoulder denervation, it requires a detailed understanding of the nerve supply to the glenohumeral and acromioclavicular joints relative to landmarks visible with image guidance. The purpose of this cadaveric study was to determine the origin, course, relationships to bony landmarks, and frequency of articular branches innervating the glenohumeral and acromioclavicular joints.

METHODS

Fifteen cadaveric specimens were meticulously dissected. The origin, course, and termination of articular branches supplying the glenohumeral and acromioclavicular joints were documented. The frequency of each branch was determined and used to generate a frequency map that included their relationships to bony and soft tissue landmarks.

RESULTS

In all specimens, the posterosuperior quadrant of the glenohumeral joint was supplied by suprascapular nerve; posteroinferior by posterior division of axillary nerve; anterosuperior by superior nerve to subscapularis; and anteroinferior by main trunk of axillary nerve. Less frequent innervation was found from lateral pectoral nerve and posterior cord. The acromioclavicular joint was found to be innervated by the lateral pectoral and acromial branch of suprascapular nerves in all specimens. Bony and soft tissue landmarks were identified to localize each nerve.

CONCLUSIONS

The frequency map of the articular branches supplying the glenohumeral and acromioclavicular joints, as well as their relationship to bony and soft tissue landmarks, provide an anatomical foundation to develop novel shoulder denervation and perioperative pain management protocols.