Axillary nerve injury: diagnosis and treatment

Distal nerve transfers for peripheral nerve injuries: indications and outcomes

Distal nerve transfer is a refined surgical technique involving the redirection of healthy sacrificable nerves from one part of the body to reinstate function in another area afflicted by paralysis or injury. This approach is particularly valuable when the original nerves are extensively damaged and standard repair methods, such as direct suturing or grafting, may be insufficient. As the nerve coaptation is close to the recipient muscles or skin, distal nerve transfers reduce the time to reinnervation. The harvesting of nerves for transfer should usually result in minimal or no donor morbidity, as any anticipated loss of function is compensated for by adjacent muscles or overlapping cutaneous territory. Recent years have witnessed notable progress in nerve transfer procedures, markedly enhancing the outcomes of upper limb reconstruction for conditions encompassing peripheral nerve, brachial plexus and spinal cord injuries.

Anatomical considerations for nerve transfer in axillary nerve injury

This study investigated the anatomical details of the axillary and radial nerves in 50 upper limbs from 29 adult formalin-embalmed cadavers, and ten fresh upper limbs. The focus was on understanding the course, division, and ramifications of these nerves to improve treatment of shoulder dysfunction caused by axillary nerve damage. The axillary nerve divided anteriorly and posteriorly before passing the quadrangular space in all specimens, with specific distances to the first ramifications. It was found that the deltoid muscle's clavicular and acromial parts were always innervated by the anterior division of the axillary nerve, whereas the spinous part was variably innervated. The longest and thickest branches of the radial nerve to the triceps muscles were identified, with no statistically significant differences in fiber numbers among triceps branches. The study concludes that nerve transfer to the anterior division of the axillary nerve can restore the deltoid muscle in about 86% of shoulders, and the teres minor muscle can be restored by nerve transfer to the posterior division. The medial head branch and long head branch of radial nerve were identified as the best donor options.

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.

Human Motor Endplate Survival after Chronic Peripheral Nerve Injury

Objective

Degeneration of motor endplates (MEPs) in denervated muscle is thought to be a key factor limiting functional regeneration after peripheral nerve injury (PNI) in humans. However, there is currently no paradigm to determine MEP status in denervated human muscle to estimate likelihood of reinnervation success. Here, we present a quantitative analysis of MEP status in biopsies of denervated muscles taken during nerve repair surgery and ensuing functional recovery.

Methods

This is a retrospective single-surgeon cohort study of patients (n=22) with upper extremity PNI confirmed with electromyography (EMG), treated with nerve transfers. Muscle biopsies were obtained intra-operatively from 10 patients for MEP morphometric analysis. Age at time of surgery ranged from 22-77 years and time from injury to surgery ranged from 2.5-163 months. Shoulder range of motion (ROM) and Medical Research Council (MRC) scores were recorded pre-op and at final follow-up.

Results

Surviving MEPs were observed in biopsies of denervated muscles from all patients, even those greater than six months from injury. Average postoperative ROM improvement (assessed between 6-9 months post-surgery) was: forward flexion 84.3 ± 51.8°, abduction 62.5 ± 47.9°, and external rotation 25.3 ± 28.0°.

Interpretation

While it is believed that MEP degeneration 6 months post-injury prevents reinnervation, this data details MEP persistence beyond this timepoint along with significant functional recovery after nerve surgery. Accordingly, persistence of MEPs in denervated muscles may predict the extent of functional recovery from nerve repair surgery.

A Surgical Framework for the Management of Incomplete Axillary Nerve Injuries

BACKGROUND

 Axillary nerve injury is the most common nerve injury affecting shoulder function. Nerve repair, grafting, and/or end-to-end nerve transfers are used to reconstruct complete neurotmetic axillary nerve injuries. While many incomplete axillary nerve injuries self-resolve, axonotmetic injuries are unpredictable, and incomplete recovery occurs. Similarly, recovery may be further inhibited by superimposed compression neuropathy at the quadrangular space. The current framework for managing incomplete axillary injuries typically does not include surgery.

METHODS

 This study is a retrospective analysis of 23 consecutive patients with incomplete axillary nerve palsy who underwent quadrangular space decompression with additional selective medial triceps to axillary end-to-side nerve transfers in 7 patients between 2015 and 2019. Primary outcome variables included the proportion of patients with shoulder abduction M3 or greater as measured on the Medical Research Council (MRC) scale, and shoulder pain measured on a Visual Analogue Scale (VAS). Secondary outcome variables included pre- and postoperative Disabilities of the Arm, Shoulder, and Hand Questionnaire (DASH) scores.

RESULTS

 A total of 23 patients met the inclusion criteria and underwent nerve surgery a mean 10.7 months after injury. Nineteen (83%) patients achieved MRC grade 3 shoulder abduction or greater after intervention, compared with only 4 (17%) patients preoperatively (p = 0.001). There was a significant decrease in VAS shoulder pain scores of 4.2 ± 2.5 preoperatively to 1.9 ± 2.4 postoperatively (p < 0.001). The DASH scores also decreased significantly from 48.8 ± 19.0 preoperatively to 30.7 ± 20.4 postoperatively (p < 0.001). Total follow-up was 17.3 ± 4.3 months.

CONCLUSION

 A surgical framework is presented for the appropriate diagnosis and surgical management of incomplete axillary nerve injury. Quadrangular space decompression with or without selective medial triceps to axillary end-to-side nerve transfers is associated with improvement in shoulder abduction strength, pain, and DASH scores in patients with incomplete axillary nerve palsy.

Posttraumatic Ruptured Axillary Mononeuropathy Without Shoulder Dislocation in an American Football Player: A Case Report and Review of the Literature

ABSTRACT

A high school-aged right-handed adolescent boy presented with a 5-mo history of persistent proximal right arm weakness and numbness after an American football stinger injury without a documented history of a shoulder dislocation or humeral fracture. He developed diffuse deltoid muscle atrophy, persistent shoulder abduction weakness, and reduced pinprick sensation confined to the axillary distribution over 5 mos. Needle electromyography demonstrated dense fibrillation potentials and no voluntary activation in all three deltoid muscle heads, indicating a severe posttraumatic ruptured axillary mononeuropathy. The patient then underwent a complex three-cable sural nerve graft repair for attempted reinnervation of the axillary-innervated muscles. Isolated axillary nerve injuries are usually associated with anterior shoulder dislocations; however, a severe isolated persistent axillary mononeuropathy from a ruptured axillary nerve may occur in trauma patients without a clear history of shoulder dislocation. These patients may present with only mild persistent weakness of shoulder abduction. Electrodiagnostic testing to fully assess axillary nerve function should still be considered to identify patients with high-grade nerve injuries that may benefit from sural nerve grafting. The rapid recovery of our patient's initial symptoms with persistent severe axillary injury suggests a unique vulnerability of the nerve due to the neuroanatomy and possibly other factors.

Rare finding of axillary artery dissection secondary to a proximal humerus fracture-dislocation: A case report

Case

Proximal humerus fractures are a relatively common injury, making up approximately 5 % of all extremity fractures. Concurrent damage to the axillary artery, however, is not a commonly associated trauma. We present a unique case of a proximal humerus fracture-dislocation resulting in an axillary artery dissection and upper extremity ischemia, requiring emergent vascular intervention.

Conclusion

Axillary artery injury secondary to a proximal humerus fracture-dislocation is a rare, but possibly devastating complication. A thorough physical examination to identify any neurovascular deficits is critical in determining an optimal and timely resolution.

Avascular Necrosis and Posttraumatic Arthritis After Proximal Humerus Fracture Internal Fixation: Evaluation and Management

PURPOSE OF REVIEW

Avascular necrosis (AVN) and posttraumatic arthritis (PTA) are common complications following both conservative treatment and open reduction and internal fixation (ORIF) of proximal humerus fractures (PHFs). Despite the frequent utilization of ORIF, information regarding these leading causes of failure is limited. This review includes a discussion of incidence, risk factors, and evaluation of AVN and PTA following PHF. The mechanisms of treatment options and associated outcomes are also reviewed.

RECENT FINDINGS

Recent best available evidence demonstrates significant rates of AVN and PTA following ORIF of PHF. This is particularly true of complex fracture patterns. A thorough workup is required in the setting of failure caused by AVN and PTA. This includes a careful patient history, clinical exam, plain film radiographs, and CT scans. EMG and/or aspiration may also be indicated. Special consideration is given to the examination of the deltoid muscle, neurovascular status, rotator cuff function, and the possibility of infection. Biological supplementation, anatomic total shoulder replacement (aTSA), and fusion are rarely employed in the treatment of AVN and/or PTA. Due to satisfactory patient outcomes, reverse total shoulder replacement (rTSA) has increased in popularity for the elderly population, while hemiarthroplasty (HA) may be appropriate for some young, active patients. With careful patient selection and meticulous surgical technique, AVN and PTA can be mitigated. Careful indications for ORIF may decrease the frequency of these complications. For most patients, rTSA is the optimal treatment option. Given the frequent utilization of ORIF and the higher than acceptable complication and failure rates, AVN and PTA warrant our attention.

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.

Iatrogenic Nerve Injuries of the Upper Extremity: A Critical Analysis Review

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Iatrogenic nerve injuries may occur after any intervention of the upper extremity.

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Causes of iatrogenic nerve lesions include direct sharp or thermal injury, retraction, compression from implants or compartment syndrome, injection, patient positioning, radiation, and cast/splint application, among others.

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Optimal treatment of iatrogenic peripheral nerve lesions relies on early and accurate diagnosis.

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Advanced imaging modalities (e.g., ultrasound and magnetic resonance imaging) and electrodiagnostic studies aid and assist in preoperative planning.

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Optimal treatment of iatrogenic injuries is situation-dependent and depends on the feasibility of direct repair, grafting, and functional transfers.

Preoperative Muscle Biopsy to Assess Motor End Plate Integrity as a Predictor for Successful Nerve Transfer: A Case Report

CASE

A 60-year-old right-hand-dominant man was referred for persistent right deltoid weakness, lateral shoulder numbness, and severe functional deficit 3 months after undergoing proximal humerus open reduction and internal fixation with plate and fibular strut allograft. Deltoid muscle biopsy demonstrated motor end plate (MEP) degeneration. After partial radial-to-axillary nerve transfer, repeat deltoid muscle biopsy revealed successful regeneration of MEPs with reinnervation of deltoid confirmed with postnerve transfer electromyography.

CONCLUSION

Selective nerve transfer can successfully rescue a denervated target muscle from further degeneration by restoration of healthy MEPs.

Transdeltoid Approach to Axillary Nerve Repair: Anatomical Study and Case Series

PURPOSE

In cases of isolated paralysis of the axillary nerve, dissection of the distal stump at the posterior deltoid border can be difficult because of scarring from an injury or previous surgery. To overcome this, we propose dissecting the anterior division of the axillary nerve (ADAN) using a deltoid-splitting approach. We investigated the anatomy of the ADAN as it pertains to the transdeltoid approach and report the clinical application of this approach in 9 patients with isolated axillary nerve injury.

METHODS

The axillary nerve and its branches were dissected in 9 fresh cadaver specimens. In the clinical series, 1 patient with a lesion confined to the ADAN underwent nerve grafting. In the remaining 8 patients, the ADAN was repaired by transferring the triceps lower medial head and anconeus (TLMA) motor branch via a single-incision or double-incision posterior arm approach.

RESULTS

The posterior division of the axillary nerve does not travel around the humerus. It innervated the posterior deltoid and teres minor muscles. At the posterior margin of the humerus, the ADAN ran adjacent to the teres minor tendon. The ADAN's trajectory on the lateral side of the humerus was 65 mm (SD ± 8 mm) from the midpoint of the acromion. One centimeter from the origin, the ADAN offered a prominent branch to the middle deltoid and wound around the humerus anteriorly at the surgical neck just distal to the infraspinatus tendon. A transdeltoid approach was feasible in all our patients. The TLMA was reached without any tension in the ADAN. Middle deltoid strength in 1 patient who had received a graft scored M3, while anterior and middle deltoid strength in the remaining patients who underwent nerve transfers scored M4.

CONCLUSIONS

With axillary nerve lesions, reinnervation of the ADAN is a priority. The transdeltoid approach between the posterior and middle deltoid offers a direct and feasible approach to the ADAN.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic V.

Elevated Body Mass Index Negatively Impacts Recovery of Shoulder Abduction Strength in Triceps Motor Branch to Axillary Nerve Transfers

BACKGROUND

The purpose of this work was to evaluate the clinical outcomes of triceps motor branch to axillary nerve transfers and to identify prognostic factors which may influence these outcomes.

METHODS

A retrospective cohort included all patients who underwent a triceps motor branch to axillary nerve transfer (2010-2019) with at least 12 months of follow-up. The primary outcome measure was shoulder abduction strength assessed with British Medical Research Council (MRC) grade.

RESULTS

Ten patients were included with a mean follow-up of 19.1 (SD 5.9) months. Compared with preoperative MRC shoulder abduction strength (0.2 SD 0.4), patients significantly improved postoperatively (2.8 SD 1.6; P = .005). Increased body mass index (BMI) was significantly associated with worse postoperative MRC (P = .014).

CONCLUSION

Triceps motor branch to axillary nerve transfer is a beneficial procedure for restoring shoulder function in patients presenting with either isolated axillary nerve or brachial plexus pathology. Patients with elevated BMI may not have as robust strength recovery and should be counseled carefully regarding prognosis.

Isolated axillary nerve palsy after liposuction, an exceptional complication

Isolated injury to the axillary nerve associated with the patient's surgical position is a very rare complication, and in most cases it is associated with the prone during spinal surgery. The presentation of this pathology in relation to surgeries of another nature is exceptional, with only a few cases in the scientific literature. We present the case of a patient who developed symptoms of isolated left axillary nerve palsy after undergoing lipoabdominoplasty and breast reduction, in which the prone and supine positions were alternated. The use of an infiltration solution with lidocaine and epinephrine could have contributed to the appearance of the lesion in this unique case. Finally, the clinical picture was fully resolved thanks to conservative treatment.

The Axillary Nerve Danger Zone in Percutaneous Fixation in the Pediatric Shoulder: The "1-Mountain-3-Valleys" Principle

BACKGROUND

Adult literature cites an axillary nerve danger zone of 5 to 7 cm distal to the acromion tip for open or percutaneous shoulder surgery, but that may not be valid for younger patients. This study sought to quantify the course of the axillary nerve in adolescent patients with reference to easily identifiable intraoperative anatomic and radiographic parameters.

METHODS

A single-institution hospital database was reviewed for shoulder magnetic resonance images (MRIs) in patients 10 to 17 years old. One hundred and one MRIs from patients with a mean age of 15.6 ± 1.2 years (range, 10 to 17 years) were included. Axillary nerve branches were identified in the coronal plane as they passed lateral to the proximal humerus and were measured in relation to identifiable intraoperative surface and radiographic landmarks, including the acromion tip, apex of the humeral head, lateral physis, and central apex of the physis. The physeal apex height (i.e., 1 "mountain") was defined as the vertical distance between the most lateral point of the humeral physis (LPHP) and the central intraosseous apex of the physis.

RESULTS

Axillary nerve branches were found in all specimens, adjacent to the lateral cortex of the proximal humerus. A mean of 3.7 branches (range, 2 to 6) were found. The mean distance from the most proximal branch (BR1) to the most distal branch (BR2) was 11.7 mm. The pediatric danger zone for the axillary nerve branches ranged from 6.6 mm proximal to 33.1 mm distal to the LPHP. The danger zone in relation to percent of physeal apex height included from 62% proximal to 242% distal to the LPHP.

CONCLUSIONS

All branches were found distal to the apex of the physis (1 "mountain" height proximal to the LPHP). Distal to the LPHP, no branches were found beyond a distance of 3 times the physeal apex height (3 "valleys"). In children and adolescents, percutaneous fixation of the proximal humerus should be performed with cortical penetration outside of this range. These parameters serve as readily identifiable intraoperative radiographic landmarks to minimize iatrogenic nerve injury.

CLINICAL RELEVANCE

This study provides valuable landmarks for percutaneous approaches to the proximal humerus. The surgical approach for the placement of percutaneous implants should be adjusted accordingly (i.e., performed at least 1 mountain proximal or 3 valleys distal to the LPHP) in order to prevent iatrogenic injury to the axillary nerve.

The humeral suspension technique: a novel operation for deltoid paralysis

Isolated deltoid paralysis is a rare pathology that can occur after axillary nerve injury due to shoulder trauma or infection. This condition leads to loss of deltoid function that can cause glenohumeral instability and inferior subluxation, resulting in rotator cuff muscle fatigue and pain. To establish dynamic glenohumeral stability, a novel technique was invented. Humeral suspension is achieved using a double button implant with non-resorbable high strength cords between the acromion and humeral head. This novel technique was used in two patients with isolated deltoid paralysis due to axillary nerve injury. The results indicate that the humeral suspension technique is a method that supports centralizing the humeral head and simultaneously dynamically stabilizes the glenohumeral joint. This approach yielded high patient satisfaction and reduced pain. Glenohumeral alignment was improved and remained intact 5 years postoperative. The humeral suspension technique is a promising surgical method for subluxated glenohumeral joint instability due to isolated deltoid paralysis.

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.

Electrodiagnostic Assessment of Uncommon Mononeuropathies

Carpal tunnel syndrome, ulnar neuropathy at the elbow, and peroneal neuropathy are the most common mononeuropathies; however, other individual nerves may also be injured by various processes. These uncommon mononeuropathies may be less readily diagnosed owing to unfamiliarity with the presentations and vague symptoms. Electrodiagnostic studies are essential in the evaluation of uncommon mononeuropathies and can assist in localization and prognostication. However, they can also be challenging; stimulation at the proximal sites is difficult and well-validated reference values are not available. This article reviews the electrodiagnostic assessment of several uncommon upper and lower extremities mononeuropathies.

Isolated axillary nerve palsy after liposuction, an exceptional complication

Isolated injury to the axillary nerve associated with the patient́s surgical position is a very rare complication, and in most cases it is associated with the prone during spinal surgery. The presentation of this pathology in relation to surgeries of another nature is exceptional, with only a few cases in the scientific literature. We present the case of a patient who developed symptoms of isolated left axillary nerve palsy after undergoing lipoabdominoplasty and breast reduction, in which the prone and supine positions were alternated. The use of an infiltration solution with lidocaine and epinephrine could have contributed to the appearance of the lesion in this unique case. Finally, the clinical picture was fully resolved thanks to conservative treatment.

Prevention and Treatment of Nerve Injuries in Shoulder Arthroplasty

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Nerve injuries during shoulder arthroplasty have traditionally been considered rare events, but recent electrodiagnostic studies have shown that intraoperative nerve trauma is relatively common.

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The brachial plexus and axillary and suprascapular nerves are the most commonly injured neurologic structures, with the radial and musculocutaneous nerves being less common sites of injury.

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Specific measures taken during the surgical approach, component implantation, and revision surgery may help to prevent direct nerve injury. Intraoperative positioning maneuvers and arm lengthening warrant consideration to minimize indirect injuries.

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Suspected nerve injuries should be investigated with electromyography preferably at 6 weeks and no later than 3 months postoperatively, allowing for primary reconstruction within 3 to 6 months of injury when indicated. Primary reconstructive options include neurolysis, direct nerve repair, nerve grafting, and nerve transfers.

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Secondary reconstruction is preferred for injuries presenting >12 months after surgery. Secondary reconstructive options with favorable outcomes include tendon transfers and free functioning muscle transfers.

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.

Neurotization of isolated axillary nerve palsy in a teenage patient

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Isolated axillary nerve palsy is a very rare condition, resulting most often from shoulder dislocation, motor vehicle accidents or iatrogenic injury.

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Loss of shoulder sensibility and abduction are the mean symptoms. And Electromyography (EMG) test helps to confirm the diagnoses.

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Long head triceps branch transfer to the axillary nerve is a good surgical procedure.

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Favorable results are associated with young age, early intervention time and adequate rehabilitation.

Background and aim

The aim of this article was to study isolated axillary nerve injury, his etiologies, symptomatology and treatment via nerve transfer or neurotization.

Methods

We describe the procedure of long head triceps radial branch transfer to the axillary nerve motor branch in adolescent patient with right deltoid muscle palsy and shoulder anesthesia following a motorcycle crush six months ago.

Results

Total recovery of the shoulder sensibility, abduction and extension at one-year follow-up, and patient returned progressively to his normal live and sports activities without any functional effect on the donor muscle.

Conclusion

The advantages of the axillary nerve transfer are demonstrated through many publications. It is a good therapeutic option if it concerned a young patient and practiced at early time followed by adequate rehabilitation.

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.

Shoulder Terrible Triad: Classification, Functional Results, and Prognostic Factors

INTRODUCTION

The shoulder terrible triad (STT) is a traumatic anterior shoulder dislocation, associated with rotator cuff (RC) tear and nerve injury from the brachial plexus. This study aimed to describe the functional results and prognostic factors of surgery in patients with STT.

METHODS

Thirty consecutive patients with acute STT were included at the same institution. All patients were examined with x-rays, MRI, and electromyography. Surgical treatment in the acute setting was indicated to address an RC injury or a displaced greater tuberosity fracture. Variables registered on the day of surgery were preoperative Constant and Western Ontario Rotator Cuff (WORC) scores and injury pattern. At final discharge, Constant, American Shoulder and Elbow Surgeons (ASES), WORC, and subjective shoulder value scores were recorded by an independent evaluator.

RESULTS

Twenty-seven patients underwent a complete follow-up. The dominant arm was affected in 50% of cases. The mean follow-up was 27 (12 to 43) months. The mean WORC and Constant scores improved from 1,543 to 1,093 (P = 0.015) and 31 to 54 (P = 0.003), respectively. The ASES and subjective shoulder value scores at the end of the follow-up were 60 and 56 points, respectively. RC tears and nerve injuries that did not involve the axillary or suprascapular nerves were associated to better results than greater tuberosity fractures and injuries to the axillary or suprascapular nerves, respectively, in WORC (P = 0.028), Constant (P = 0.024), and ASES scores (P = 0.035). Preoperative WORC and Constant scores were independent prognostic factors.

CONCLUSIONS

The most frequent patterns include complete RC tears, anterior capsular injuries, and an axillary nerve injury. Patients had improved functional scores at the end of follow-up after surgery. Better functional results were correlated to RC tears, injuries to nerves with innervation distal to the shoulder, and higher preoperative Constant and WORC scores.

Isolated Axillary Nerve Injury in an Elite High School American Football Player: A Case Report

An elite high school American football athlete sustained a traumatic, isolated, axillary nerve injury. Axillary nerve injuries are uncommon, but serious injuries in American football. With the advent of nerve transfers and grafts, these injuries, if diagnosed in a timely manner, are treatable. This case report discusses the multidisciplinary approach necessary for the diagnosis and treatment of an elite high school American football player who presented with marked deltoid atrophy. The athlete's injury was diagnosed via electrodiagnostic testing and he underwent a medial triceps nerve to axillary nerve transfer. After appropriate postsurgical therapy, the athlete was able to return to American football the subsequent season and continue performing at an elite level. This case report reviews the evaluation and modern treatment for axillary nerve injuries in the athlete, including nerve transfers, nerve grafts, and return to play.

Radial-to-Axillary Nerve Transfer Resolves Symptoms of Axillary Nerve Injury Due to Proximal Humerus Fracture-Dislocation in an Elderly Patient Treated With Hemiarthroplasty

Proximal humerus fractures in elderly patients are a common injury that can often be treated nonoperatively. However, surgery is indicated with some fracture patterns. Arthroplasty is an attractive option with poor bone quality, when there is a low likelihood of success with open reduction and internal fixation, and due to a timely return to function and weight bearing of the extremity in this patient population. A prerequisite for shoulder function for both native and replacement joints is a functional deltoid. Unfortunately, elderly patients with complex fracture patterns can sustain axillary nerve palsies that make management more difficult. The authors present a case of an elderly patient with a complex fracture-dislocation of the proximal humerus with traumatic axillary nerve palsy treated with hemiarthroplasty, followed by radial-to-axillary nerve transfer after the deltoid failed to improve. Congruency of the joint was restored and significant improvement in objective scoring metrics was achieved, making nerve transfer in this clinical scenario a viable option. [Orthopedics. 2019; 42(4):e395-e398.].

Risk of Axillary Nerve Injury in Standard Anterolateral Approach of Shoulder: Cadaveric Study

Introduction: The anterolateral acromion approach of the shoulder is popular for minimally invasive plate osteosynthesis (MIPO) technique. However, there are literatures describing the specific risks of injury of the axillary nerve using this approach. Nevertheless, most of the studies were done with Caucasian cadavers. So, the purpose of this study was to evaluate the risk of iatrogenic axillary nerve injury from using the anterolateral shoulder approach and further investigate the location of the axillary nerve, associated with its location and arm length in the Asian population that have shorter arm length compared to the Caucasian population.

Materials and Methods: Seventy-nine shoulders in fourty-two embalmed cadavers were evaluated. The bony landmarks were drawn, and a vertical straight incision was made 5cm from tip of the acromion (anterolateral approach), to the bone. The iatrogenic nerve injury status and the distance between the anterolateral edge of the acromion to the axillary nerve was measured and recorded.

Results: In ten of the seventy-nine shoulders, the axillary nerve were iatrogenically injured. The average anterior distance was 6.4cm and the average arm length was 30.2cm. The anterior distance and arm length ratio was 0.2.

Conclusion: Our results demonstrated that the recommended safe zone at 5cm from tip of acromion was not suitable with Asian population due to shorter arm length, compared to Caucasian population. The location of axillary nerve could be predicted by 20% of the total arm-length.

Triceps motor branch transfer for isolated axillary nerve injury: Outcomes in 9 patients

INTRODUCTION

Triceps motor branch transfer has been used for more than ten years to restore deltoid function after axillary nerve injury. However, there have been few reports of the outcome of this procedure in isolated axillary nerve injury.

HYPOTHESIS

Triceps motor branch transfer could be an effective method to restore deltoid function for patients with isolated axillary nerve injury.

MATERIALS AND METHODS

Nine patients who underwent triceps motor branch transfer for treatment of isolated axillary nerve injury were followed up for at least 22 months. Shoulder abduction was assessed for all patients. The DASH outcome questionnaire was completed by every patient. Electrophysiological study was performed on 7 patients.

RESULTS

All patients regained≥90° (mean, 137°) shoulder abduction. Mean DASH score decreased from 35.2 before surgery to 13.1 at the last follow-up. There was no noticeable weakness of elbow extension in any patient.

DISCUSSION

Triceps motor branch transfer provided good results and may be a feasible alternative to nerve grafting for the treatment of complete isolated axillary nerve injury.

TYPE OF STUDY

IV, retrospective cohort study.

Shoulder function in patients with deltoid paralysis and intact rotator cuff

INTRODUCTION/HYPOTHESIS

The purpose of this study is to determine the mid/long term shoulder function in patients with complete deltoid paralysis and intact rotator cuff. 27 patients with at least 2-years FU were included.

MATERIALS AND METHODS

Outcome measures included pain, range of motion (including the swallowtail test STT), deltoid extension lag test DELT and Bertelli test), subjective fatigability using the injured shoulder and postoperative modified Neer ratings.

RESULTS

At an average 68 months FU, mean shoulder abduction was 131°, flexion 153°, external rotation with the arm at the side 58° and 58° with the arm abducted. All patients reported quick fatiguability with repetitive use of the injured arm which did not change over time. Average pain score was 2. Eighteen patients had positive STT and DELT tests and all patients had positive Bertelli test.

DISCUSSION

This study demonstrates that patients with deltoid paralysis and intact rotator cuff do maintain most of their shoulder function and this is sustained over time.

LEVEL OF EVIDENCE

Level IV; prognostic Study: case series.

Change in the Distance From the Axillary Nerve to the Glenohumeral Joint With Shoulder External Rotation or Abduction Position

BACKGROUND

This study investigated whether axillary nerve (AN) distance to the inferior border of the humeral head and inferior glenoid would change while placing the glenohumeral joint in different degrees of external rotation and abduction.

METHODS

A standard deltopectoral approach was performed on 10 fresh-frozen cadaveric specimens. The distance between AN and the inferior border of the humeral head and inferior glenoid while placing the shoulder in 0°, 45°, and 90° of external rotation or abduction was measured. Continuous variables for changes in AN position were compared with paired 2-tailed Student t test.

RESULTS

The mean distance between the AN and the humeral head with the shoulder in 0°, 45°, and 90° of external rotation and 0° of abduction was 13.77 mm (SD 4.31), 13.99 mm (SD 4.12), and 16.28 mm (SD 5.40), respectively. The mean distance between the AN and glenoid with the shoulder in 0°, 45°, and 90° of external rotation was 16.33 mm (SD 3.60), 15.60 mm (SD 4.19), and 16.43 (SD 5.35), respectively. The mean distance between the AN and the humeral head with the shoulder in 0°, 45°, and 90° of abduction and 0° of external rotation was 13.76 mm (SD 4.31), 10.68 mm (SD 4.19), and 3.81 mm (SD 3.08), respectively. The mean distance between the AN and glenoid with the shoulder in 0°, 45°, and 90° of abduction was 16.33 mm (SD 3.60), 17.66 mm (SD 5.80), and 12.44 mm (SD 5.57), respectively.

CONCLUSIONS

The AN position relative to the inferior aspect of the glenohumeral joint does not significantly change despite position of external rotation. Increasing shoulder abduction over 45° decreases the distance from the glenohumeral joint to the AN and should be avoided.

Axon Counts Yield Multiple Options for Triceps Fascicular Nerve to Axillary Nerve Transfer

PURPOSE

To evaluate the relative axonal match between potential donor and recipient nerves, so that maximal reinnervation potential may be reached with the least chance of donor site morbidity.

METHODS

In 10 fresh-frozen cadaveric specimens, the main trunk and anterior, posterior, sensory and teres minor branches of the axillary nerve were identified, as were the radial nerve branches to the long, medial, and lateral heads of the triceps. The swing distances of the triceps fascicular nerve branches and the axillary nerve branches relative to the inferior border of the teres major muscle were recorded. Histomorphological analysis and axon counts were performed on sections of each branch.

RESULTS

The median number of axons in the main axillary trunk was 7,887, with 4,052, 1,242, and 1,161 axons in the anterior, posterior, and teres minor branches, respectively. All specimens had a single long head triceps branch (median, 2,302 axons), a range of 1 to 3 branches to the medial head of the triceps (composite axon count, 2,198 axons), and 1 to 3 branches to the lateral head of the triceps (composite average, 1,462 axons). The medial and lateral head branches had sufficient swing distance to reach the anterior branch of the axillary nerve in all 10 specimens, with only 4 specimens having adequate long head branch swing distances.

CONCLUSIONS

It is anatomically feasible to transfer multiple branches of the radial nerve supplying the medial, lateral, and sometimes, long head of the triceps to all branches of the axillary nerve in an attempt to reinnervate the deltoid and teres minor muscles.

CLINICAL RELEVANCE

Understanding the axon counts of the different possible transfer combinations will improve operative flexibility and enable peripheral nerve surgeons to reinnervate for both abduction and external rotation with the highest donor/recipient axon count ratios.

Beyond the Cuff: MR Imaging of Labroligamentous Injuries in the Athletic Shoulder

Shoulder disease is common in the athletic population and may arise as a consequence of a single traumatic episode or multiple repeated events. Associated labroligamentous injuries can result in substantial disability. Specific athletic and occupational activities result in predictable injury patterns. Imaging in general and magnetic resonance (MR) imaging, in particular, are vital in establishing the correct diagnosis and excluding common mimicking conditions, to ensure timely and appropriate management. In this review, the utility of MR imaging and MR arthrography will be explored in evaluation of shoulder disease, taking into account normal variants of the labroligamentous complex. Subsequently, broad categories of labral lesions and instability, external and internal impingement, as well as nerve entrapment syndromes, will be discussed, while emphasizing their imaging findings in the clinical context and illustrating key features. More recent concepts of internal impingement and secondary subacromial impingement will also be clarified.

Nerve Transfers to Restore Shoulder Function

The restoration of shoulder function after brachial plexus injury represents a significant challenge facing the peripheral nerve surgeons. This is owing to a combination of the complex biomechanics of the shoulder girdle, the multitude of muscles and nerves that could be potentially injured, and a limited number of donor options. In general, nerve transfer is favored over tendon transfer, because the biomechanics of the musculotendinous units are not altered. This article summarizes the surgical techniques and clinical results of nerve transfers for restoration of shoulder function.

Nerve transfers and neurotization in peripheral nerve injury, from surgery to rehabilitation

Peripheral nerve injury (PNI) and recent advances in nerve reconstruction (such as neurotization with nerve transfers) have improved outcomes for patients suffering peripheral nerve trauma. The purpose of this paper is to bridge the gap between the electromyographer/clinical neurophysiologist and the peripheral nerve surgeon. Whereas the preceding literature focuses on either the basic science behind nerve injury and reconstruction, or the surgical options and algorithms, this paper demonstrates how electromyography is not just a 'decision tool' when deciding whether to operate but is also essential to all phases of PNI management including surgery and rehabilitation. The recent advances in the reconstruction and rehabilitation of PNI is demonstrated using case examples to assist the electromyographer to understand modern surgical techniques and the unique demands they ask from electrodiagnostic testing.

Axillary Nerve Reconstruction: Anterior-Posterior Exposure With Sural Nerve Cable Graft Pull-Through Technique

Deltoid paralysis after axillary nerve injury results in limitations in shoulder function and stability. In the setting of an isolated axillary nerve injury with no clinical or electromyographic evidence of recovery that is within 6 to 9 months postinjury, the authors' preferred technique to reinnervate the deltoid is to reconstruct the axillary nerve with sural nerve grafting. Intraoperative neuromuscular electrophysiology is critical to determine the continuity of the axillary nerve before proceeding with reconstruction. The majority of the time, both an anterior and posterior incision and dissection of the axillary nerve is required to adequately delineate the zone of injury. This also ensures that both proximally and distally, uninjured axillary nerve is present before graft inset and also facilitates the ability to perform a meticulous microsurgical inset of the nerve graft posteriorly. The nerve graft must be pulled through from posterior to anterior to span the zone of injury and reconstruct the axillary nerve. Careful infraclavicular brachial plexus dissection is necessary to prevent further injury to components of the brachial plexus in the setting of a scarred bed. Patients will require postoperative therapy to prevent limitations in shoulder range of motion secondary to postoperative stiffness. This paper presents a detailed surgical technique for axillary nerve reconstruction by an anterior-posterior approach with a pull-through technique of a sural nerve cable graft.

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

Quadrilateral space syndrome (QSS) arises from compression or mechanical injury to the axillary nerve or the posterior circumflex humeral artery (PCHA) as they pass through the quadrilateral space (QS). Quadrilateral space syndrome is an uncommon cause of paresthesia and an underdiagnosed cause of digital ischemia in overhead athletes. Quadrilateral space syndrome can present with neurogenic symptoms (pain and weakness) secondary to axillary nerve compression. In addition, repeated abduction and external rotation of the arm is felt to lead to injury of the PCHA within the QSS. This often results in PCHA thrombosis and aneurysm formation, with distal emboli. Because of relative infrequency, QSS is rarely diagnosed on evaluation of athletes with such symptoms. We report on 9 patients who presented at Mayo Clinic with QSS. Differential diagnosis, a new classification system, and the management of QSS are discussed, with a comprehensive literature review. The following search terms were used on PubMed: axillary nerve, posterior circumflex humeral artery, quadrilateral space, and quadrangular space. Articles were selected if they described patients with symptoms from axillary nerve entrapment or PCHA thrombosis, or if related screening or imaging methods were assessed. References available within the obtained articles were also pursued. There was no date or language restriction for article inclusion; 5 studies in languages besides English were reported in German, French, Spanish, Turkish, and Chinese.

Radial to axillary nerve neurotization for brachial plexus injury in children: a combined case series

OBJECT

Axillary nerve palsy, isolated or as part of a more complex brachial plexus injury, can have profound effects on upper-extremity function. Radial to axillary nerve neurotization is a useful technique for regaining shoulder abduction with little compromise of other neurological function. A combined experience of this procedure used in children is reviewed.

METHODS

A retrospective review of the authors' experience across 3 tertiary care centers with brachial plexus and peripheral nerve injury in children (younger than 18 years) revealed 7 cases involving patients with axillary nerve injury as part of an overall brachial plexus injury with persistent shoulder abduction deficits. Two surgical approaches to the region were used.

RESULTS

Four infants (ages 0.6, 0.8, 0.8, and 0.6 years) and 3 older children (ages 8, 15, and 17 years) underwent surgical intervention. No patient had significant shoulder abduction past 15° preoperatively. In 3 cases, additional neurotization was performed in conjunction with the procedure of interest. Two surgical approaches were used: posterior and transaxillary. All patients displayed improvement in shoulder abduction. All were able to activate their deltoid muscle to raise their arm against gravity and 4 of 7 were able to abduct against resistance. The median duration of follow-up was 15 months (range 8 months to 5.9 years).

CONCLUSIONS

Radial to axillary nerve neurotization improved shoulder abduction in this series of patients treated at 3 institutions. While rarely used in children, this neurotization procedure is an excellent option to restore deltoid function in children with brachial plexus injury due to birth or accidental trauma.

Nerve transfer from triceps medial head and anconeus to deltoid for axillary nerve palsy

PURPOSE

To report our results with reconstruction of the axillary nerve by transferring the branch to the triceps lower medial head and anconeus to the anterior division of the axillary nerve.

METHODS

This study included 9 patients with isolated injury of the axillary nerve. Their average age ± SD was 35 ± 9 years, and the mean interval ± SD between injury and surgery was 6.6 ± 2.6 months. Through a posterior arm approach, the radial nerve branch to the lower triceps medial head and anconeus was transferred to the anterior division of the axillary nerve. We observed patients for a mean of 34 ± 7 months. At final evaluation, we measured range of shoulder motion, shoulder abduction and elbow extension strength, and abduction endurance. Patients were assessed via the deltoid extension lag test and abduction-in-internal-rotation test.

RESULTS

All patients recovered deltoid function and maintained full active elbow extension. Seven of 9 patients recovered from lagging abduction in internal rotation. Abduction strength improved from approximately 40% that of the normal side at 90° of abduction preoperatively to 60% of normal strength postoperatively. There was improved endurance in abduction from approximately 25% to 65% that of the normal side, which was sufficient to eliminate all reports of shoulder pain or fatigability.

CONCLUSIONS

Transfer of the radial nerve branch for the lower triceps medial head and anconeus to the anterior division of the axillary nerve proved to be an effective method of deltoid reinnervation.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic IV.

The deltoid, a forgotten muscle of the shoulder

The deltoid is a fascinating muscle with a significant role in shoulder function. It is comprised of three distinct portions (anterior or clavicular, middle or acromial, and posterior or spinal) and acts mainly as an abductor of the shoulder and stabilizer of the humeral head. Deltoid tears are not infrequently associated with large or massive rotator cuff tears and may further jeopardize shoulder function. A variety of other pathologies may affect the deltoid muscle including enthesitis, calcific tendinitis, myositis, infection, tumors, and chronic avulsion injury. Contracture of the deltoid following repeated intramuscular injections could present with progressive abduction deformity and winging of the scapula. The deltoid muscle and its innervating axillary nerve may be injured during shoulder surgery, which may have disastrous functional consequences. Axillary neuropathies leading to deltoid muscle dysfunction include traumatic injuries, quadrilateral space and Parsonage-Turner syndromes, and cause denervation of the deltoid muscle. Finally, abnormalities of the deltoid may originate from nearby pathologies of subdeltoid bursa, acromion, and distal clavicle.

Evaluation and treatment of upper extremity nerve entrapment syndromes

Nerve entrapment syndromes in the upper extremity are being recognized with increasing frequency. Prompt and correct diagnosis of these injuries is important. This article is a review of the common entrapment nerve injuries seen in the upper extremity. Each of these clinical syndromes is discussed independently, reviewing the anatomy, compression sites, patient presentation (history and examination), the role of additional diagnostic studies, and management.

An association between the inferior humeral head osteophyte and teres minor fatty infiltration: evidence for axillary nerve entrapment in glenohumeral osteoarthritis

BACKGROUND

Glenohumeral osteoarthritis often results in inferior humeral osteophytes. Anatomic studies suggest that the axillary neurovascular bundle is in close proximity to the glenohumeral capsule. We therefore hypothesize that an inferior humeral osteophyte of sufficient magnitude could encroach on the axillary nerve and result in measurable fatty infiltration of the teres minor muscle.

MATERIALS AND METHODS

Preoperative magnetic resonance imaging studies of 91 consecutive arthritic shoulders were retrospectively reviewed. Two cohorts were established based on the presence of a humeral osteophyte. The distances from the axillary neurovascular bundle to various osseous structures were measured using calibrated software. Objective quantitative measurements of the degree of fatty infiltration of the teres minor muscles were obtained with image analysis software. Results were compared between cohorts.

RESULTS

The distance between the inferior humerus and axillary neurovascular bundle was inversely correlated to the size of the inferior humeral osteophyte (ρ = -0.631, P < .001). Fatty infiltration of the teres minor was greater when an inferior osteophyte was present (11.9%) than when an osteophyte was not present (4.4%) (P = .004). A statistically significant correlation between the size of the humeral head spur and quantity of fat in the teres minor muscle belly (ρ = 0.297, P = .005) was identified.

CONCLUSION

These data are consistent with our hypothesis that the axillary nerve may be entrapped by the inferior humeral osteophyte often presenting with glenohumeral osteoarthritis. Entrapment may affect axillary nerve function and lead to changes in the teres minor muscle. Axillary neuropathy from an inferior humeral osteophyte may represent a contributing and treatable cause of pain in patients with glenohumeral osteoarthritis.

Axillary nerve injury in young adults--an overlooked diagnosis? Early results of nerve reconstruction and nerve transfers

An injury to the axillary nerve from a shoulder trauma can easily be overlooked. Spontaneous functional recovery may occur, but occasionally reconstructive surgery is required. The time frame for nerve reconstruction procedures is from a neurobiological view crucial for a good functional outcome. This study presents a group of operatively and non-operatively treated young adults with axillary nerve injuries caused by motorcycle accidents, where the diagnosis was set late. Ten young men (median age at trauma 13 years, range 9-24) with an axillary nerve injury were diagnosed by examination of shoulder function and electromyography (EMG). The patients had either a nerve reconstruction procedure or were treated conservatively and their recovery was monitored. The axillary nerve was explored and reconstructed at a median of 8 months (range 1-22 months) after trauma in 8/10 patients. Two patients were treated non-operatively. In 4/8 cases, a reconstruction with sural nerve graft was performed and in 1/8 case only exploration of the nerve was made (minor neuroma). In 3/8 cases a radial nerve branch transfer to the axillary nerve was chosen as the procedure. The shoulder was mobilised after 3 weeks with physiotherapy and the patients were monitored regularly. Functional recovery was observed in 9/10 cases (median follow up 11 months, range 7-64) with EMG signs of reinnervation in seven patients. Axillary nerve function should not be overlooked in young patients with a minor shoulder trauma. Nerve reconstruction can successfully recreate function.