1. Anthony Perugini Dr – OhioHealth Orthopedic Surgery Residency
2. Braden Passias Dr. – OhioHealth Orthopedic Surgery Residency
3. Satvam Mehta Mr. – Lewis Katz School of Medicine
4. James Iandoli Dr. – OhioHealth Orthopedic Surgery Residency
5. Anthony Wing Dr. – OhioHealth Orthopedic Surgery Residency
6. Sanjay Mehta Dr. – OhioHealth Grant Medical Center

Abstract
Introduction: Femoral neck fractures are common injuries that typically occur in an aging population. Compared to older patients, young patients sustaining femoral neck fractures should undergo prompt intervention with anatomic reduction for optimal outcomes. Although rare, there have been case reports of bilateral femoral neck fractures in younger patients with underlying metabolic pathology.

Methods
A 28-year-old male with a known history of multilevel lumbar compression fractures and disc herniations presented with low back pain and bilateral leg pain after being tased during a training exercise at work. After initial evaluation, including the patient ambulating for several days, secondary survey revealed bilateral sub-capital femoral neck fractures.

Results
Intraoperative specimens sent for pathologic analysis revealed changes consistent with avascular necrosis of the femoral neck.

Conclusions
This case highlights the importance of a secondary survey in the evaluation and clinical monitoring of a patient, and suggests radiographic examination should be considered in patients after an electrical injury with subsequent difficulty ambulating.

Keywords: bilateral femoral neck fracture, orthopedics, taser gun, electrical injury, femoral neck avascular necrosis

Introduction
Femoral neck fractures are common injuries that typically occur in an aging population. With an increase in the elderly population, the incidence of hip fractures is also on the rise(1). Certain risk factors such as female gender, decreased mobility, endocrine disorders, medications, and low bone density can predispose patients to femoral neck fractures(2, 3). Economically, hip fractures and subsequent management are a significant burden to the medical system(4) and are associated with an increase in morbidity and mortality.

Contrary to fragility fractures in elderly, femoral neck fractures in younger patient populations are classically associated with high-energy traumatic mechanism; this subsection of the bimodal distribution seen in femoral neck injuries represents less than 5% of all hip fractures(5). In younger patients there is significant risk of avascular necrosis and fracture nonunion, which is secondary to the tenuous intracapsular blood supply of the femoral neck(6, 7); subsequently prompt intervention with anatomic reduction is warranted for optimal outcomes(8). Although rare, there have been case reports of bilateral femoral neck fractures in the setting of metabolic bone diseases such as osteodystrophy, rickets/osteomalacia, and osteoporosis(9-11). In the younger population, surgical management typically consists of fracture fixation, with total hip arthroplasty being indicated in the elderly or unique cases(12).

To date, no manuscript has discussed the implications of a taser gun as a possible mechanism of femoral neck fractures. The purpose of this study is to report a unique presentation of atraumatic taser-induced bilateral femoral neck fractures in a young patient.

Statement of Informed Consent: Verbal consent was obtained from the patient with knowledge that details, data, and surgical intraoperative photos of this case would be submitted for publication and deidentified to the best of our ability and the patient agreed.

Case Presentation
A 28-year-old male security guard with a known history of lumbar compression fractures and disc herniations presented as a transfer to our emergency department from an outside hospital with low back pain and bilateral leg pain after a taser incident earlier that day. As part of a work training exercise, the patient volunteered to be tased by two tasers simultaneously. During the demonstration, he was standing with arms interlocked and held by coworkers as the tasers were deployed, striking his right scapular area, low back, buttocks, and right posterior thigh. After deployment, he was lowered to his knees by coworkers as to not fall to the ground. He then transferred to a chair. After rising from a chair, he reported hearing a loud pop and immediately fell to the ground.  

Initially, he was seen at an outside hospital before transfer to our facility secondary to difficulty with ambulation. Upon presentation to an urban, level-1 trauma center, he ambulated into the emergency department without assistance. Despite his independent ambulatory status, he continued to endorse low back pain with bilateral lower extremity weakness. On initial survey the patient had intact rectal tone, the presence of saddle anesthesia, and right greater than left lower extremity weakness. He had bilateral atraumatic lower extremities with full active and passive range of motion and negative log roll tests. Upon further questioning, the patient endorsed sustaining lumbar compression fractures and disc herniations from prior remote weightlifting events. He denied any past medical history, was not currently taking any medications, had no history of steroid or alcohol abuse. He further denied any recreational, illicit, or performance-enhancing drug use.

Due to his known history of lumbar disease and clinical saddle anesthesia, in the emergency department the patient acutely underwent dedicated computed tomography (CT) scanning of the thoracic and lumbar spine which revealed no acute pathology or deviation from previous imaging. A trial of a muscle relaxant resulted in minimal improvement symptomatology, and the patient was then admitted for observation and formal neurosurgical evaluation.

With a normal neurologic exam and benign advanced imaging of the thoracic and lumbar spine, the patient was cleared by neurosurgery the subsequent day. He was to work with occupational and physical therapy teams to address ambulation and self-care needs. Four days after admission, he was not progressing with therapies and began complaining of anterior pelvic pain and persistent leg pain, at which point the primary team ordered plain films and a computed tomography scan of the pelvis which revealed right comminuted sub-capital and left segmental femoral neck fractures (Figures 1 and 2, respectively). Subsequently, orthopedic surgery was consulted. Due to the delayed presentation and risk of femoral head avascular necrosis, the patient was subsequently taken for staged bilateral total hip arthroplasty.

During both operations, a standard anterolateral approach was used. In the initial right total hip arthroplasty surgery, upon dissection of the right hip, it was noted that the patient had a stout ligamentum teres which presented difficulty with femoral head extraction. Four days later, the patient underwent left total hip arthroplasty. Upon evaluation of the left femoral neck fracture, the segmental fracture appeared to have smooth edges despite the acuteness of the mechanism of injury. During both operations, a Biomet G7 OsseoTi acetabular component (56 mm shell, F liner), a Biomet TaperLock complete micro primary femoral porous coated stem (13 x 111 mm high offset type 1 taper) stem, and Biolox Delta modular ceramic head (36 mm) were utilized during total hip arthroplasties. Both femoral head intraoperative specimens were sent for pathology (Figure 3). Pathologic analysis revealed avascular necrosis of the femoral necks at the fracture site.

Following his bilateral hip replacements, he was discharged from the hospital on post operative day three (from his stage two operation) without any complications. Postoperative imaging revealed that prostheses were well aligned (Figure 4). The patient has been seen for follow up most recently at his 3 month post-operative visit. Hardware is in good alignment without complication. Clinically, he has currently returned to work without restriction. Hs is able to perform all activities of daily living without reservation and ambulates with a cane as precautionary measure.

Discussion
This report presents a unique case of a young gentleman that suffered bilateral femoral neck fractures induced by an electrical shock injury. This case poses unique considerations, as the fractures were not discovered until nearly four days after the original injury. Diagnostic buriers for this injury lie in the unusual mechanism of injury being a taser gun and the patient’s benign clinical examination with independent ambulatory status upon arrival to our facility.

Electrical shock can cause various types of injuries to different organ systems of the body. Orthopedically, electrical shock injuries can most commonly cause joint dislocations or fractures secondary to the subsequent overpowering muscular force that is stimulated. Classically this can result in posterior glenohumeral dislocations, scapular fractures, and thoracic compression fractures(13-15). Associated fractures with an acute electrical shock often result from a fall at the initial time of injury, contrary to this unique case presentation.

This clinical case presents an outside source of electrical stimulation and the resulting orthopedic injuries. One such case from Ritchie et al.(16) describes a patient sustaining bilateral sub-capital femoral neck fractures and thoracic vertebral body fractures after dropping a blender into a bathtub during a suicide attempt. This case highlighted the implications of underlying chronic renal disease and metabolic conditions resulting in fracture from a low voltage electrical current. Similar incidences of traumatic injuries have been described in the setting of tonic-clonic seizure activity(17). It has been described that tonic-clonic seizure activity can induce a femoral neck fracture in an elderly patient(17). Similarly, historically there have been few reports of femoral neck fractures associated with electroconvulsive therapy(18). Contrary to the aforementioned literature, this clinical scenario presents that of a similar injury, however bilateral in presentation, in healthy, non-osteoporotic bone.

Given the patient’s history of lumbar compression fractures and disc herniations, one could certainly postulate these injuries mark a predisposition for fracture. After discussion with the patient, these injuries were sustained during weight lifting competitions years prior and had clinically resolved. Nonetheless, the patient has no prior evidence of metabolic derangement such as osteodystrophy or renal disease. Further, he has no additional preceding factors that would otherwise place him at risk such as recreational or medical steroid use.

The histopathology of intraoperative bone biopsies further complicates this case. Pathologic analysis demonstrated “avascular necrosis” of the level of the femoral neck. Grossly, the specimen measured 3.5 cm x 2.7 cm x 1.5 cm appeared to have “smooth texture that is tan with trabecular bone” as opposed to the rest of the specimen that had “red-brown, ragged, hemorrhagic, trabecular bone.” Given the results from pathology, one can surmise there may be some contribution to a prior injury. With smooth surfaces, a more chronic non-united SCFE or other prior fracture could have predisposed this patient to his injury.

The clinical diagnosis of bilateral femoral neck fractures in a young ambulatory patient who suffered an electrical injury poses not only a diagnostic challenge, but also a treatment challenge. Traditional traumatic treatment algorithm using the Garden classification dictates whether or not to “fix” or “replace,” with advantages and disadvantages to each(19). With a completely displaced fracture pattern, that presented more than 72 hours after the injury to the orthopedic team, the attending physician elected to treat with a total hip arthroplasty. Urgent reduction and fracture fixation can lead to intracapsular decompression and unkinking of vessels to the femoral head reducing the risk of osteonecrosis and non-union(20). Femoral neck fractures with injury occurring greater than 24-72 hours of intervention have a decreased likelihood of union(21), albeit highly controversial(22). Replacement however comes with several disadvantages as subsequent revision rate for these patients is not insignificant with some studies reporting as high as 13%(23). Furthermore, the etiology of revision total hip arthroplasty in younger patients is typically due to acetabular loosening, femoral loosening, or polyethylene wear, which is more prevalent compared to older patient counterparts(24).

We present a unique and challenging case in a patient with bilateral femoral neck fractures; delayed presentation, independent ambulatory status, and an electrical shock injury mechanism posed as both diagnostic and treatment challenges.

Figure 1 | Figure 2 | Figure 3 | Figure 4

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