Orthopedics

Case Report 

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

Chad B. Willis, MD; Shahryar Ahmadi, MD, FRCSC

Abstract

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.]

Abstract

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.]

Proximal humerus fractures are a common injury, representing 4% to 5% of all fractures.1 Older patients tend to sustain more complicated fracture patterns of the proximal humerus than their younger counterparts.2 Elderly patients are also more likely to sustain a nerve palsy, with the axillary nerve commonly implicated.3 These fractures in elderly patients, in combination with nerve injury, can make treatment complex.4

Hemiarthroplasty is an attractive option for 3- and 4-part fractures in elderly patients.4 However, functional results are poorer with concomitant nerve injury. In this scenario, nerve transfer is an option to salvage function. The current authors describe a patient of the classic demographic for a complex fracture-dislocation of the proximal humerus with an associated axillary nerve palsy who was treated with hemiarthroplasty followed by radial-to-axillary nerve transfer and had satisfactory return of function. The technique has been described by Salazar et al5 in reverse shoulder arthroplasty for chronic axillary palsy. To the current authors' knowledge, this technique has not been demonstrated for hemiarthroplasty. The authors present the clinical presentation, surgical technique, and final clinical results.

Case Report

A 69-year-old right-hand–dominant woman fell backward onto her outstretched arm as she lost her footing on a boat deck. She had no previous injury to the shoulder and her medical history was noncontributory to her condition. She was evaluated by an on-board physician who diagnosed a fracture-dislocation of her shoulder and attempted closed reduction without success. Unfortunately, pre- and post-reduction radiographs were unavailable. She was placed in a sling and was flown to land for management of her injury.

She presented to the authors' institution's emergency department 4 days after injury. On initial examination by the orthopedic resident, she was noted to be intact neurovascularly to the hand with paresthesias in the axillary distribution. At this point, her diagnosis of 4-part proximal humerus fracture with inferior head dislocation was confirmed. An attempted closed reduction performed in the emergency department under sedation failed (Figure 1).

Anteroposterior (A) and axillary lateral (B) radiographs of the patient's proximal humerus fracture-dislocation at initial presentation to the academic institution. Axillary lateral radiograph obtained after attempted closed reduction under sedation in the emergency department at initial presentation (C).

Figure 1:

Anteroposterior (A) and axillary lateral (B) radiographs of the patient's proximal humerus fracture-dislocation at initial presentation to the academic institution. Axillary lateral radiograph obtained after attempted closed reduction under sedation in the emergency department at initial presentation (C).

She was evaluated by the senior author (S.A.) and treatment options were explained. She was offered hemiarthroplasty for her injury. A preoperative computed tomography scan was ordered for surgical planning, illustrating the humeral head lodged in the axilla within the margins of the coracobrachialis, subscapularis, and teres major. No other bony injuries were identified.

She underwent surgery 2 days after presentation. Cemented hemiarthroplasty was performed using the Shoulder Arthroplasty System (Zimmer Biomet, Warsaw, Indiana). Intraoperatively, a hole in the glenohumeral joint capsule was identified that allowed the head to be extracted. After retrieval of the fragment, implantation of arthroplasty components was uneventful. Prior to wound closure, the axillary nerve was noted to be in continuity by palpation under the deltoid distally and the medial portion of subscapularis proximally. Review of intraoperative fluoroscopy and postoperative radiographs revealed the components to be in good position with appropriate position of the tuberosities.

At her first postoperative visit, she was noted to have inferior subluxation of the humeral component with numbness over her lateral deltoid and absent motor function (Figure 2). Her subluxation was attributed to an incompetent deltoid secondary to axillary nerve palsy. At that time, it was elected to continue to observe for signs of improvement before further diagnostic studies were performed.

Follow-up anteroposterior (A) and axillary lateral (B) radiographs of the affected shoulder obtained 2 weeks following implantation, illustrating subluxation of the humerus on the glenoid.

Figure 2:

Follow-up anteroposterior (A) and axillary lateral (B) radiographs of the affected shoulder obtained 2 weeks following implantation, illustrating subluxation of the humerus on the glenoid.

At 4-month follow-up, no improvement in axillary nerve function was observed. Nerve conduction studies were completed at 6 months from injury, revealing subacute denervation of the deltoid. This finding was observed for another 6 weeks without signs of improvement despite physical therapy. Her active forward flexion and abduction were 60° and 45°, respectively, at 8 months from the index surgery, with persistent inferior subluxation of her hemiarthroplasty. Functional scores documented an American Shoulder and Elbow Surgeons score of 15.03 and a Disabilities of the Arm, Shoulder and Hand score of 83.6, with a work module score of 75.0.

At 11 months from the time of hemiarthroplasty, the patient returned to the operating room for radial-to-axillary nerve transfer. A posterior approach was used to access the quadrangular space to identify the axillary nerve. A nerve stimulator was used and confirmed no muscular contraction to be present. The medial branch of the radial nerve innervating the triceps was identified and dissected to provide appropriate length for transfer. The axillary nerve was dissected out in a similar fashion. The 2 nerve endings were approximated within the surgical field, and epineural sutures were used for transfer. This repair was then wrapped with a NeuraGen tube (Integra LifeSciences, Plainsboro Township, New Jersey). A standard postoperative protocol was instituted consisting of non–weight bearing in a sling until her first follow-up appointment 2 weeks postoperatively.

At 3 months postoperative from nerve transfer, deltoid contraction was observed with significant strength. At 6 months postoperatively, radiographs showed marked improvement without inferior subluxation of the humeral head (Figure 3). Her active forward flexion and external rotation at 6 months following nerve transfer were 130° and 45°, respectively. Follow-up questionnaires at 18 months after her nerve transfer documented an American Shoulder and Elbow Surgeons score of 84.9 and a Disabilities of the Arm, Shoulder and Hand score of 8.6.

Follow-up anteroposterior (A) and axillary lateral (B) radiographs obtained 6 months following radial-to-axillary nerve transfer, illustrating reduction of the humerus into the glenoid.

Figure 3:

Follow-up anteroposterior (A) and axillary lateral (B) radiographs obtained 6 months following radial-to-axillary nerve transfer, illustrating reduction of the humerus into the glenoid.

Discussion

Axillary nerve injury limits shoulder abduction and hinders patients' abilities to perform activities of daily living that require overhead activity, as well as affects shoulder stability.6 Nonoperative treatment is the mainstay, with focus on physical therapy to maintain joint mobility and avoid contracture.7

For patients who fail to recover function, surgical options include nerve grafting, nerve transfer, and muscle transfers.7–9 Data remain conflicted on which procedure provides better functional outcomes, but nerve grafting and transfer are the most documented in the literature.6,10 Those supporting grafting theorize a higher concentration of axons available for regeneration.6 Advocates of radial-to-axillary nerve transfer cite the relative simplicity of the procedure, earlier regeneration secondary to closer proximity to the motor endplate, bypass of the zone of injury, and avoidance of donor site morbidity.6,11

Previously, nerve transfer has been described in the setting of isolated axillary nerve injury,6 upper brachial plexus injury,12 and rotator cuff arthropathy,5 all of which rely on a functioning deltoid for shoulder abduction with good-to-excellent results reported. Two techniques have been described, with Witoonchart et al13 using the nerve to the long head of the triceps and Mackinnon et el14 using the medial triceps branch, citing an easier dissection and longer length.

Desai et al15 presented a series of 27 patients with axillary nerve injuries treated with radial-to-axillary transfer, with 3 patients experiencing palsy following shoulder hemiarthroplasty and 7 patients demonstrating no axillary nerve function following some variation of an arthroplasty procedure. Although this may seem analogous to the current patient, it is noteworthy that the reason arthroplasty was performed is not stated and preoperative palsy is unknown in that series of patients. Given the history of the current authors' patient with dislocation of the humeral head into the axillary space, her palsy was most likely secondary to her trauma rather than iatrogenic, as described in the series presented by Desai et al.15

Currently, no data exist regarding information on the time of presentation and subsequent axillary nerve dysfunction. However, the literature cites rates of axillary nerve injury with glenohumeral dislocation in the range of 13.5% to 48%, with increased susceptibility in elderly patients and those with fractures.3,16 This resolves within 6 to 12 months in a majority of patients, although a subset of patients have a permanent deficit.16 In the current authors' patient, nerve studies 6 months from injury demonstrated denervation and there was no clinical return of function at 11 months, thus the decision was made to proceed with nerve transfer.

Thus far, no cases of radial-to-axillary nerve transfer following hemiarthroplasty with traumatic axillary nerve palsy and glenohumeral subluxation have been reported. Both hemiarthroplasty and reverse-total shoulder are frequent treatment options offered to older patients with 3- to 4-part proximal humerus fractures. Hemiarthroplasty remains a viable option for proximal humerus fractures with reducible tuberosities and a functioning rotator cuff. However, inferior subluxation poses a significant problem, indicating that the rotator cuff is struggling to maintain congruency of the shoulder and that the deltoid is not providing sufficient assistance. Unfortunately, a functioning deltoid is a requisite for reverse total shoulder arthroplasty as well. By restoring deltoid function using radial-to-axillary nerve transfer, the authors illustrate resolution of an inferior subluxation. Functional outcomes improved markedly after nerve transfer surgery, with an increase in the American Shoulder and Elbow Surgeons score from 15.0 to 84.9 and a decrease in the Disabilities of the Arm, Shoulder and Hand score from 83.6 to 8.6.

Conclusion

Axillary nerve function is crucial to functionality of native shoulders, as well as arthroplasties. Inferior subluxation of the shoulder, a consequence of axillary nerve dysfunction, poses a difficult problem that causes both pain and functional deficits. The current patient demonstrated excellent results following radial-to-axillary nerve transfer in the setting of hemiarthroplasty with axillary nerve palsy. This technique is a viable option for patients with native and replacement joints.

References

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Authors

The authors are from the Department of Orthopaedic Surgery, University of Arkansas–Medical Sciences, Little Rock, Arkansas.

The authors have no relevant financial relationships to disclose.

Correspondence should be addressed to: Chad B. Willis, MD, Department of Orthopaedic Surgery, University of Arkansas–Medical Sciences, 4301 W Markham St, Slot 531, Little Rock, AR 72205 ( cbwillis@uams.edu).

Received: December 22, 2018
Accepted: February 14, 2019

10.3928/01477447-20190624-07

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