Type III intra-articular entrapment of the median nerve following elbow dislocation in an adult patient: A case report

Abstract

Introduction

Traumatic entrapment of the median nerve within the elbow joint is a rare condition and primarily affects children and adolescents. It may occur following elbow dislocations or fracture-dislocations.

Presentation of case

A 33-year-old woman presented one week after sustaining an elbow dislocation, reporting severe pain and symptoms of median nerve dysfunction. After the failure of conservative treatment, surgical exploration, performed the following week, revealed a type III intra-articular entrapment (neve looped inside the joint). Nerve decompression was successfully executed, and no postoperative complications were observed. At the two-year follow-up, the patient reported no pain and had returned to work with minimal functional limitations.

Discussion

To date, just over 50 cases of traumatic median nerve entrapment have been documented in the literature. It is typically classified into four anatomical types, with types I and II being the most prevalent. In a literature review, we found only seven reported cases of type III entrapment in patients between 4 and 18 years of age. Therefore, this may represent the first reported case of type III entrapment in a patient older than 18 years.

Conclusion

This report describes a rare case and highlights that achieving a favorable outcome in cases of intra-articular nerve entrapment depends on early clinical suspicion, timely diagnosis, and prompt surgical intervention.

Highlights

• •Traumatic nerve entrapments are rare pathological conditions in medical practice.
• •The median nerve can become entrapped after elbow dislocations and fracture-dislocations.
• •A high degree of suspicion is necessary to distinguish nerve entrapment from neurapraxia or section.
• •Prompt surgical treatment is warranted in nerve entrapment suspicious cases to improve prognosis.

1. Introduction

While chronic entrapments, such as carpal tunnel syndrome, and traumatic injuries to peripheral nerves are relatively common in daily medical practice [1,2], traumatic intra-articular entrapments are extremely rare pathological conditions [3,4].

Elbow dislocations and fracture-dislocations are a frequent reason for consultation in orthopaedic emergency settings among all age groups – children, adolescents, and adults [3]. Fortunately, adjacent vascular and nerve involvement occurs in a small percentage of cases, reaching up to only 5 % following an elbow dislocation [3].

We present an unusual case of median nerve entrapment within the elbow joint in an adult patient, emphasizing the critical role of clinical suspicion in diagnosis and treatment.

This case report has been reported in line with the updated SCARE criteria [5]. No Artificial Intelligence was used in the research and manuscript development. The patient was informed that data of her case would be submitted for publication, and the appropriate consent form was signed.

2. Case report

A 33-year-old right-handed woman employed in private security, with no relevant medical history, sustained an isolated posterior dislocation of the right elbow after falling off a horse (Fig. 1A and B). Closed reduction was performed under general anesthesia at another facility, followed by immobilization with a plaster splint at 90° of elbow flexion on the same day of the injury.

Fig. 1.

Initial anteroposterior (A) and lateral (B) radiographs showing posterior dislocation of the right elbow. Follow-up anteroposterior (C) and lateral (D) radiographs taken 1 week later.

One week later, the patient came to our hospital due to persistent severe pain, unrelieved by medication, accompanied by hypoesthesia of the right elbow, forearm, and hand. A tightly applied bandage was found and removed along with the splint. Physical examination revealed significant swelling of the elbow and proximal forearm, extensive ecchymosis, severe pain upon attempted elbow movement, and near-complete loss of sensory and motor function in the median nerve distribution. Muscle strength was graded 1/5 in the flexor pollicis longus and the flexor digitorum profundus of the index finger, and 2/5 in the flexor carpi radialis. Two-point discrimination exceeded 15 mm on the volar surface of the thumb, index, and middle fingers, as well as the radial half of the palm. Strength was preserved (5/5) in muscles innervated by the radial and ulnar nerves, and sensation was normal in their respective cutaneous territories. A positive Tinel's sign was present on the volar aspect of the elbow and proximal forearm.

Radiographs were obtained, confirming a reduced joint and absence of fractures (Fig. 1C and D). After ruling out compartment syndrome, the patient was managed conservatively with a sling, pain medication, and physical therapy involving passive and assisted mobilization.

After one week without improvement, a dynamic ultrasound was performed, which revealed the absence of a segment of the median nerve at the level of the elbow (Fig. 2), prompting the decision for immediate surgical exploration.

Fig. 2.

Ultrasound images. Longitudinal view of the median nerve (measurement lines) in the forearm (A), and transverse view at the elbow showing disappearance of a segment of the median nerve (B).

The patient was taken to the operating room and positioned supine with a lateral support table. Under general anesthesia and with a pneumatic tourniquet inflated to 250 mmHg on the upper arm, an anteromedial approach to the elbow was performed. The origin of the flexor-pronator muscle group and the insertion of the brachialis muscle were exposed. The median nerve was clearly identified a few centimeters proximal and distal to the joint. Dissection was carried out toward the center of the incision and the nerve was found forming a loop within the humeroulnar joint through a capsular tear caused by the dislocation, corresponding to a type III entrapment (Fig. 3A and B) [3].

Fig. 3.

Intraoperative photographs of the right elbow, proximal = right, distal = left. (A) Exposure of the median nerve (*), which loops into the humeroulnar joint (solid black arrow). (B) Defect in the joint capsule through which the joint is visible after nerve extraction (outlined arrow). (C) Nerve following micro-neurolysis and capsule after repair.

By manually subluxating the joint, the nerve was carefully dissected and released. It appeared contused and surrounded by fibrous tissue, but continuity was preserved. Under magnification, both epineural and fascicular neurolysis were performed and no significant damage to the nerve was observed. The joint capsule was repaired using absorbable sutures and final intraoperative assessment showed no evidence of impingement during flexion-extension of the elbow (Fig. 3C). The incision was closed in layers in a standard fashion.

The limb was not immobilized in a splint; instead the wound was covered with a gauze dressing, and movement was allowed as tolerated from the beginning. During the first postoperative days, the patient experienced moderate pain and dysesthesias, which were successfully managed with medications including etoricoxib, acetaminophen, tramadol, and pregabalin. Cutaneous sutures were removed in the office at two weeks, and the wound healed without complications. Physical therapy was started at that time, three times per week, and included range-of-motion exercises, gradual strengthening, and sensory re-education.

Over the following months, the patient demonstrated steady neurological improvement, with gradual recovery of motor and sensory function in the median nerve distribution.

At the 6-month follow-up visit, although some pain persisted (VAS 3/10), muscle strength had improved to 3/5 in the wrist and hand muscles innervated by the median nerve. Elbow range of motion was 45°–100°. The patient had not yet returned to previous work and was still on pregabalin treatment. At one year after surgery, pain had nearly resolved, occurring only occasionally at night, and muscle strength continued to improve.

At the 2-year follow-up after surgery, muscle strength had improved to 4+/5 in the flexor pollicis longus, flexor digitorum profundus of the index finger, and flexor carpi radialis (Fig. 4A). Two-point discrimination measured 4 mm on the thumb, index, and middle fingers, and 10 mm on the radial half of the palm. Final elbow range of motion was 25°–125° (Fig. 4B). The patient resumed occupational and daily activities with few to no difficulties (DASH score 5/100), and no pain. Final follow-up radiographs were normal.

Fig. 4.

Clinical photographs showing recovery of hand function (A) and elbow range of motion (B) at the patient's final follow-up.

3. Discussion

Traumatic entrapment of the median nerve within the elbow joint is an exceedingly rare injury, predominantly observed in children and adolescents [3,6], with only anecdotal reports in adults [7]. The first documented case was reported by Gurdjian and Smathers in 1945 in a 7-year-old boy who underwent surgery 5.5 months post-injury [8]. Since then, just over 50 cases have been described [3,4,[9], [10], [11], [12], [13], [14], [15]].

This condition typically arises following an elbow dislocation or subluxation accompanied by ligamentous injury, detachment of the flexor muscle origin, or fractures of the epicondyles [3,7,16]. During the reduction of the injury, the median nerve may become interposed within the joint or trapped inside the fracture site.

The most widely used classification is that proposed by Fourrier et al. in 1977 (Fig. 5) [16,17]. In Type I, an avulsion fracture of the medial epicondyle or a tear at the origin of the flexor muscles allows the nerve to displace posteriorly along the medial aspect and become lodged within the joint. In Type II, the nerve becomes entrapped within a medial epicondyle fracture that subsequently consolidates around it. Notably, Type III is characterized by the nerve forming a loop that becomes captured between the humerus and the coronoid process. Furthermore, Type IV, proposed by Al-Qattan et al. in 1994, represents a combination of Types I and II [18]. In 2018, McCarthy et al. proposed Type V – entrapment of the nerve within a fracture of an unossified medial epicondyle [9], essentially a variant of Type II seen in younger children.

Fig. 5.

Modified Fourier classification of intra-articular median nerve entrapment at the elbow.

(Reproduced from Montanari et al. [3] with permission from Elsevier.)

Two recent literature reviews by Montanari et al. [3] and Domingue et al. [4] identified 44 published cases in patients aged 4 to 18 years. The most common pattern was Type I (32.5 %), followed by Type II (27.5 %), Type IV (22.5 %), and Type III (17.5 %) [3,4]. We identified nine additional cases in the English literature involving patients aged 2.5 to 30 years [7,9,[11], [12], [13], [14], [15]].

Most cases showed a significant delay in diagnosis and treatment, sometimes extending to several years. Therefore, a high index of clinical suspicion is essential, as these injuries can easily be mistaken for post-traumatic pain or neurapraxia.

Ultrasound is an excellent diagnostic tool in these scenarios: it is widely available, quick to perform, cost-effective, well-tolerated by children, allows for dynamic evaluation of nerve mobility, and facilitates easy comparison with the contralateral side [3,10,19].

Magnetic resonance imaging (MRI) has also proven useful, although its interpretation is more complex and may require sedation or anesthesia in pediatric patients [4,10,13,19]. Nerve conduction studies are typically reserved for chronic cases, particularly beyond four weeks post-injury [3,6,15].

The ideal treatment consists of early surgical decompression, generally accompanied by neurolysis [11]. In neglected cases, it is often necessary to resect the damaged segment and perform end-to-end nerve anastomosis or grafting [3]. In the absence of recovery after primary surgery or long-standing chronic cases, tendon or nerve transfers should be considered [15]. It is worth emphasizing that prognosis is directly impacted by delays in diagnosis and intervention [3,4].

To the best of our knowledge, this is the first published case of a Type III median nerve entrapment in an adult patient (33 years old), as a comprehensive literature review revealed only seven reported cases of type III entrapment in patients between 4 and 18 years of age [3,4,9,[11], [12], [13], [14], [15]]. The only other case documented to date in an adult describes a different entrapment type in a 30-year-old woman, in whom the nerve was entrapped within the site of a dislocation associated with a lateral epicondyle fracture [7].

4. Conclusion

Intra-articular median nerve entrapment, though exceptional, should be suspected when neurological deficits persist or emerge after reduction of an elbow dislocation, especially in children and adolescents. Moreover, physicians should be aware that nerve entrapment in fractures or dislocations, although rare, may also occur in other joints or fracture sites. Once compartment syndrome has been ruled out, careful and repeated neurological examination, comparison with the contralateral limb, and early use of ultrasound or MRI are essential to distinguish this complication from more common nerve injuries. If entrapment is confirmed or strongly suspected, timely surgical exploration is warranted to prevent permanent deficits.

CRediT authorship contribution statement

• Marco Carrion-Monsalve (mcarrion2@gmail.com): Surgeon. Follow-up care. Conceptualization. Data curation. Supervision. Validation. Visualization. Writing – original draft. Writing – review & editing.

• Fulvio Zuñiga-Cabrera (fulviozc@hotmail.com): Surgeon. Conceptualization. Supervision. Validation. Writing – review & editing.

• Maritza Guillen-Vanegas (maritzag40@hotmail.com): Data curation. Methodology. Validation. Writing – original draft. Writing – review & editing.

• Fernando Carrion-Torres (fcarriontorres@icloud.com): Investigation. Methodology. Validation. Writing – original draft. Writing – review & editing.

Consent

Written informed consent was obtained from the patient for publication of this case report and accompanying images, while maintaining the patient's anonymity.

Ethical approval

In compliance with current legal regulations and institutional research guidelines, this project is considered exempt from review by the Human Research Ethics Committee of the authors' institution, as it involves a properly anonymized single-patient case report.

Guarantor

Marco Carrion-Monsalve.

Funding

This research did not receive any specific grant from funding agencies in the public, commercial, or non-for-profit sectors.

Declaration of competing interest

The authors declare that they have no conflicts of interest related to the preparation of this article.

Data availability

All data pertaining to this case is available from the corresponding author upon reasonable request.