Axillary nerve lesions after open reduction and internal fixation of proximal humeral fractures through an extended lateral deltoid-split approach: electrophysiological findings

[Translated article] Electromyographic axillary nerve injury in fractures of the proximal humerus: Prospective, observational study, analysing the fracture pattern

OBJECTIVE

Description and analysis of the relation between the proximal humerus fracture patterns and the traumatic injury of the axillary nerve.

MATERIAL AND METHOD

Prospective, observational study of a consecutive case series that analysed proximal humerus fractures. Radiographic evaluation was performed, and AO (Arbeitsgemeinshaft für Osteosynsthesefragen) system was used to classify the fractures. Electromyography was used to diagnose the axillary nerve injury.

RESULTS

Thirty-one patients on 105 who had a proximal humerus fracture met inclusion criteria. Eighty-six percent of the patients included were women and 14% men. The mean age was 71.8 years (30-96 years). Of the patients included in the study, 58% had normal or mild axonotmesis EMG, 23% had axillary nerve neuropathy without muscle denervation and 19% had injury with axillary nerve denervation. Patients who suffered complex fractures of the proximal humerus (AO11B and AO11C) had a higher risk of presenting axillary neuropathy type lesions with muscle denervation in the EMG, this relationship being statistically significant (p<0.001).

CONCLUSION

Patients who have more risk on presenting axillary nerve neuropathy with muscle denervation in electromyography are those who present complex proximal humerus fractures AO11B and AO11C (p<0.001).

Electromyographic axillary nerve injury in fractures of the proximal humerus: Prospective, observational study, analysing the fracture pattern

OBJECTIVE

Description and analysis of the relation between the proximal humerus fracture patterns and the traumatic injury of the axillary nerve.

MATERIAL AND METHOD

Prospective, observational study of a consecutive case series that analyzed proximal humerus fractures. Radiographic evaluation was performed, and AO (Arbeitsgemeinshaft für Osteosynsthesefragen) system was used to classify the fractures. Electromyography was used to diagnose the axillary nerve injury.

RESULTS

Thirty-one patients on 105 who had a proximal humerus fracture met inclusion criteria. Eighty-six percent of the patients included were women and 14% men. The mean age was 71.8 years (30-96 years). Of the patients included in the study, 58% had normal or mild axonotmesis EMG, 23% had axillary nerve neuropathy without muscle denervation and 19% had injury with axillary nerve denervation. Patients who suffered complex fractures of the proximal humerus (AO11B and AO11C) had a higher risk of presenting axillary neuropathy type lesions with muscle denervation in the EMG, this relationship being statistically significant (p<0.001).

CONCLUSION

Patients who have more risk on presenting axillary nerve neuropathy with muscle denervation in electromyography are those who present complex proximal humerus fractures AO11B and AO11C (p<0.001).

Stabilization of Comminuted Fractures of the Proximal Humerus with Intramedullary Nails and Angularly Stable Locking Plates—Functional Results before and during the SARS-COVID-19 Pandemics

Background and Objectives: Intramedullary nailing (IMN) and angularly stable plating (ASP) are the most popular techniques for the stabilization of comminuted fractures of the proximal humerus, without either one being obviously superior. The aim of the study was to validate the functional outcomes of both stabilization techniques in the COVID-19 pandemic by comparing them with data obtained just before the pandemic, because the limitations of the COVID-19 pandemic are affecting several aspects of social and medical life—being afraid of the transmission of the infection, patients reduce their exposure to healthcare to absolutely essential emergencies. Moreover, working conditions in the operating theater have also become more restrictive. Materials and Methods: Investigations were performed on 112 adult patients with Neer’s three- and four-fragment fractures stabilized with IMN (64) and ASP (48). Treatment effects were validated six months after surgery based on radiographs for evidence of bone union, humeral neck–shaft angle (NSA) and implant placement. Limb function was assessed with the QuickDash and Constant–Murley scores. Data obtained from patients treated in the COVID-19 pandemic were compared with those obtained before the pandemic. Results: The healing of all fractures was satisfactory, but complications developed in six cases. Three patients required secondary interventions due to inadequate repositioning: one after IMN and two after ASP. Additionally, one ASP was complicated by the secondary destabilization of a primarily properly stabilized major tubercle, and in two cases by conflict of the protruding implant with the acromion. ASP was noted to provide better functional results during the COVID-19 pandemic according to the Constant–Murley score (p = 0.0048; Student’s t-test). No significant differences were observed in the pre-COVID-19 pandemic. Conclusions: Our results suggest that ASP is more beneficial for the stabilization of comminuted fractures of the proximal humerus during the COVID-19 pandemic.

The use of medial support screw was associated with axillary nerve injury after plate fixation of proximal humeral fracture using minimal invasive deltoid-splitting approach

BACKGROUND

The purpose of this study was to evaluate the incidence and risk factors for axillary nerve injury after plate fixation of humeral fractures using minimal invasive deltoid-splitting approach. We hypothesized that the use of medial support screw (MSS) would be associated with the outcome of axillary nerve injury.

METHODS

This study retrospectively evaluated consecutive 32 patients who underwent surgical treatments for proximal or midshaft humeral fractures. Of them, we included 26 patients who were examined by electromyography/nerve conduction (EMG/NCV) study at 3-4 weeks postoperatively. We excluded 6 patients because two of them were not compliant to EMG/NCV and the remaining two died due to unrelated medical illness. Outcome assessments included pain, functional scores, range of motion, and radiographic results.

RESULTS

There were 8 male and 18 female patients with mean age of 67 ± 15 years. Mean duration of follow-up period was 31 ± 11 months. The mean time to EMG/NCS after surgery was 3.5 ± 0.6 weeks. EMG/NCS examinations revealed incomplete axillary nerve injury in 8 patients (31%) without complete nerve injury. Active forward elevation at 3 months postoperatively was significantly lower in patients with axillary nerve injury than in those without it (99° ± 12 and 123° ± 37, respectively, p = 0.047), although final clinical outcomes were not different. At surgery, MSS was used in 17 patients (65%), and 8 of them were associated with nerve injury. The use of MSS was only correlated with the outcome of axillary nerve injury, because the axillary nerve injury developed only in MSS group (p = 0.047). The MMT grade 4 in abduction strength was more common in patients with axillary nerve injury than in those without (p = 0.037).

CONCLUSIONS

Axillary nerve injury was a concern after plate fixation of proximal humeral fracture using minimal invasive deltoid-splitting approach. The use of medial support screw to improve the stability could increase a risk of axillary nerve injury when used with this approach.

Is there any clinical significance of axillary nerve electrophysiological changes in the deltoid split approach?

Purpose

The clinical effects of axillary nerve injury in the deltoid splitting approach are controversial. This study investigated the axillary nerve function with clinical and electrophysiologically in proximal humeral fracture patients with internal fixation using the deltoid split approach. We also aimed to investigate the effects of this damage on deltoid muscle volume and discuss the effects of volumetric changes and nerve damage on patients' clinical outcomes.

Methods

study designed prospectively with 25 consecutive patients who received open reduction and internal fixation of proximal humerus fracture through a deltoid splitting approach. We performed clinical, electrophysiological, and radiological examinations during minimum follow-up time of 24 months. Electrophysiological examination comprised electromyoneurography (EMNG). Functional results followed by Constant-Murley and Disabilities of the Arm, Shoulder, and Hand scores. Deltoid volumes were evaluated with magnetic resonance imaging.

Results

Twenty-five patients operated on with open reduction internal fixation were prospectively observed. In the EMNG measurements of the patients on the 45th postoperative day, partial degeneration was observed in the anterior part of the axillary nerve in all cases (100%). In the control EMNG measurements performed at the 12th month, normal values were obtained for 15 (60%) of the patients, while findings of ongoing regeneration were detected for 10 (40%) of the patients and normal values at all patients at the 24th month. The difference between abnormal and normal EMNG groups' on 12th month Constant-Murley scores was not statistically significant in any period. Only anterior muscle thickness was statistically higher in the normal patient group than with abnormal EMNG results.

Conclusions

In proximal humeral fractures treated with the deltoid split approach, there may be iatrogenic damage of the anterior branch of the axillary nerve. Axillary nerve damage does not affect the patients' clinical scores in the early and mid-terms.

Level of evidence

LEVEL III.

The Relationship Between Arm Abduction Position and the Risk of Iatrogenic Anterior Branch of the Axillary Nerve Injuries: A Cadaveric Study

Background:

The axillary nerve is at risk for iatrogenic injuries in surgical procedures involving the lateral aspect of the shoulder joint. To date and to our knowledge, there have been no studies that have compared the relevant distances in the common arm abduction positions used in these types of surgery as well as the relative risks of each position.

Purpose:

To evaluate the effect of arm abduction position on the distance from the acromion process to the axillary nerve in the common abducted arm positions.

Study Design:

Descriptive laboratory study.

Methods:

The shoulders of 10 fresh-frozen, full-body cadaveric specimens were used. A saber incision was made at the anterolateral edge of the acromion, and the anterior branch of the axillary nerve was identified. The distance between the anterolateral edge of the acromion process and the axillary nerve was measured 3 times in each of 4 positions: with the arm at the side as well as at 30°, 60°, and 90° of abduction. Then, the same procedure was performed from the midlateral and the posterolateral edges of the acromion process. The distances of the acromion process to the axillary nerve in the 4 positions were compared using 2-way analysis of variance.

Results:

The mean distances from the anterolateral edge of the acromion process to the anterior branch of the axillary nerve were 52.76 ± 4.64 mm with the arm at the side, 49.48 ± 4.77 mm at 30° of abduction, 46.00 ± 4.75 mm at 60° of abduction, and 42.88 ± 4.59 mm at 90° of abduction. There was a significant decrease in the distance from the anterolateral edge of the acromion process to the axillary nerve as the abduction angle of the arm increased from 0° to 60°, 0° to 90°, and 30° to 90° (P < .05).

Conclusion:

The distances from the acromion process to the axillary nerve were shorter in all abducted arm positions than with the arm at the side.

Clinical Relevance:

To avoid iatrogenic axillary nerve injuries, surgeons should be aware of the safe zone based on the shortest distance from the acromion process to the axillary nerve to ensure no accidental damage to this structure instead of using the mean distance of 5 cm.

MRI evaluation of axillary neurovascular bundle: Implications for minimally invasive proximal humerus fracture fixation

Background

Percutaneous fixation of proximal humeral fractures places the axillary nerve and posterior humeral circumflex artery at risk for injury. Safe operative zones for the axillary nerve are described based on external measurements from anatomic landmarks, but no study to date has incorporated advanced imaging to help guide surgical procedures in the region of the axillary neurovascular bundle (ANVB). We sought to define the location and trajectory of the ANVB in relation to osseous landmarks using magnetic resonance imaging (MRI) measurements.

Methods

Retrospective review of 750 consecutive MRI studies was performed with 55 imaging studies meeting inclusion criteria for patient positioning, image alignment, and quality. Five measurements were performed including the distance from mid-lateral acromion to lateral ANVB, mid-lateral acromion to medial ANVB, greater tuberosity to lateral ANVB, vertical distance between inferior anatomic neck and lateral ANVB, and angle the ANVB crosses the humerus. Height, gender, and age were recorded. Analysis was performed using ANOVA and Pearson correlation tests.

Results

The lateral ANVB was below the inferior articular margin of the humeral head by an average of 12.9 ± 3.9 mm and within a 22 mm window. It was an average of 57.4 ± 5.1 mm from the lateral mid-acromion, and 34.7 ± 4.3 mm below the greater tuberosity. The angle formed by the ANVB crossing the humerus averaged 19.5 ± 3.9 degrees upward from medial to lateral. Height and gender directly impacted measurements.

Conclusions

The use of the inferior humeral head articular margin provides a radiographic landmark to aid intraoperative lateral ANVB assessment which may be helpful during percutaneous fracture fixation.

Increased Medial Displacement of the Humeral Shaft of at Least 40% Correlates With an Increased Incidence of Nerve Injury in Proximal Humerus Fractures

BACKGROUND

Peripheral nerve and infraclavicular brachial plexus injury following proximal humerus fractures are commonplace, but diagnosing a concomitant nerve injury in the acute setting is challenging. Fracture displacement has been identified as a qualitative risk factor for nerve injury, and additional attention should be paid to the neurologic exams of patients with proximal humerus fractures with significant medial shaft displacement. However, a quantitative relationship between the risk of nerve injury and medialization of the humeral shaft has not been shown, and additional risk factors for this complication have not been assessed. The aim of this study was to identify the risk factors for a neurologic deficit following a proximal humerus fracture, with particular interest in the utility of the magnitude of medial shaft displacement as a predictor of neurologic dysfunction.

METHODS

A retrospective chart review was performed on all proximal humerus fractures in a 3-year period (2012-2015) at a level one trauma center. Isolated greater tuberosity fractures (OTA 11-A1) were excluded. Fracture displacement was measured on initial injury AP shoulder radiograph and expressed as a percentage of humeral diaphyseal width. All orthopedic inpatient documentation was assessed to identify clinical neurologic deficits.

RESULTS

We identified 139 patients for inclusion. There were 22 patients (16%) with new neurologic deficits at presentation (8 axillary nerve, 2 radial nerve, 12 infraclavicular brachial plexus or multiple nerve injuries). The average shaft medial displacement in patients with neurologic injuries was 59% vs. 21% without nerve deficits (p=0.03). Using a 40% medial displacement threshold, the odds ratio for a nerve injury was 5.24 (95% CI 1.54 - 17.77, p=.008).

CONCLUSION

Increased medial displacement of the humeral shaft following proximal humerus fracture is associated with an increased incidence of nerve injury at the time of initial presentation. This finding is not meant to be a surrogate for a high-quality neurologic exam in all patients with proximal humerus fractures. However, improved knowledge of the specific risk factors for an occult neurologic injury will improve the clinician's ability to accurately diagnose and properly treat proximal humerus fractures and their sequelae.Level of Evidence: III.

Effect of surgical approaches on deltoid innervation and clinical outcomes in the treatment of proximal humeral fractures

Objectives

This study aims to investigate the effects of deltopectoral and anterolateral acromial approaches commonly used in open reduction-internal fixation of proximal humeral fractures on the clinical outcomes, and axillary nerve damage through electrophysiological assessment.

Patients and methods

Forty-eight patients (22 males, 26 females; mean age 47.9±13.2 years; range, 22 to 73 years) diagnosed with Arbeitsgemeinschaft für Osteosynthesefragen (AO)/Orthopaedic Trauma Association (OTA) type 11 proximal humeral fractures who underwent osteosynthesis with anatomical locking plates in our hospital between January 2015 and June 2016 were prospectively examined. The patients were divided into two groups according to either the deltopectoral or anterolateral deltoid-split surgical approach used. Clinical outcomes were evaluated using the Disabilities of the Arm, Shoulder, and Hand (DASH) scores and Constant-Murley scores (CMS) obtained at three- and 12-month follow-up visits. Needle electromyography (EMG) was performed for the electrophysiological assessment of the deltoid muscle.

Results

There were no significant differences between the groups in terms of demographic data, follow-up times, and complications. DASH scores and CMS obtained postoperatively at three months (p=0.327 and p=0.531, respectively) and 12 months (p=0.324 and p=0.648, respectively) revealed no significant differences. In addition, the two groups did not significantly differ with respect to the presence of EMG abnormalities (p=0.792). Avascular necrosis of the humeral head was detected in only two patients from the deltopectoral group.

Conclusion

Deltopectoral and anterolateral approaches do not differ regarding the presence of postoperative EMG abnormalities and functional outcomes. Surgeons can thus adopt either approach. However, dissection without damaging the soft tissue should be performed in both approaches.

Deltopectoral Approach for Arthroplasty After Early Failed Proximal Humerus Fixation Via Deltoid Split Heals Uneventfully: A Case Report

CASE

A 57-year-old male carpenter sustained a 2-part displaced proximal humerus fracture of his nondominant arm with varus angulation after a fall down the stairs. Fifteen days postinjury, the patient underwent direct reduction and surgical fixation with an intramedullary cage implant via a deltoid split approach. Nine days postsurgery, the patient presented to the emergency department after another fall with failed fixation. Two weeks after index surgery, he was revised to a reverse total shoulder arthroplasty via a deltopectoral approach and healed both incisions uneventfully.

CONCLUSION

A deltopectoral approach performed acutely after a deltoid split approach for fracture can heal uneventfully.

Modified minimally invasive approach and intra-osseous portal for three-part proximal humeral fractures: a comparative study

BACKGROUND

Proximal humeral fracture is a common fracture. Different approaches have been utilized in the surgical intervention of three-part fractures. Our study is to evaluate the clinical outcomes and effectiveness of a modified anterolateral approach and intra-osseous portal in minimally invasive treatment for three-part proximal humeral fractures in comparison to the traditional deltopectoral approach.

METHODS

From March 2015 to September 2016, 13 patients with three-part proximal humeral fractures were treated with internal fixation through the modified anterolateral minimally invasive approach (MIPO). These cases were compared to 20 additional cases using the deltopectoral approach (DP). Clinical and radiographic evaluations were performed, including the constant score (CS) and range of motion in abduction, flexion/extension and external/internal rotation. Complications were recorded as well.

RESULTS

All patients were followed up for a mean time of 12.12 ± 4.01 months. At the latest follow-up, no significant differences (p < 0.05) were observed in terms of length of stay, range of motion for abduction, flexion or internal/external rotation of the shoulder, Constant score or visual analog scors (VAS) for pain. Elbow flexion (142.31 ± 8.32 vs. 123.00 ± 10.18), posterior shoulder extension (41.92 ± 5.22 vs. 35.50 ± 5.83) and postoperative VAS (4.38 ± 1.04 vs. 6.15 ± 0.99) were significantly better in the MIPO group than in the DP group (p < 0.05). No significant differences were detected in the radiographic evaluation, and complications including axillary nerve injury were not present.

CONCLUSION

The use of the modified anterolateral approach and intra-osseous portal is safe and effective for minimally invasive reduction and plating treatment for three-part proximal humeral fractures.