Isolated lateral radial head dislocation in a child: A case report and literature review

Abstract

Introduction

Radial head dislocations in children can result from congenital anomalies, traumatic events, or as part of more complex injuries like Monteggia fractures. These dislocations are rare and may be overlooked unless considered in differential diagnoses.

Case presentation

We describe a unique instance of a post-traumatic isolated lateral radial head dislocation in a 5-year-old boy with no previous medical concerns. The child presented with persistent pain and limited mobility in the left elbow following an unwitnessed fall at home. Diagnosis was confirmed via radiographs showing the dislocation without associated fractures. Closed reduction under anesthesia was successfully performed.

Clinical discussion

This case underscores the importance of a high index of suspicion and thorough imaging in diagnosing pediatric radial head dislocations. Our discussion includes a review of the literature and the clinical approach for managing such injuries, highlighting the specifics of the closed reduction technique used.

Conclusion

Isolated lateral radial head dislocations, although rare, can occur and are amenable to closed reduction. This case contributes to the limited reports of such dislocations in pediatric patients, emphasizing the need for awareness and precise management strategies to prevent long-term complications.

Highlights

• •First case of child's isolated lateral radial head dislocation documented.
• •Closed reduction under anesthesia effectively managed the dislocation.
• •Described practical reduction techniques for similar pediatric cases.
• •Successful long-term outcome underscores importance of continuous monitoring.

1. Introduction

Isolated radial head dislocation in the pediatric population is a relatively rare condition. It is most commonly associated with congenital anomalies such as Ehlers-Danlos syndrome and trisomy 8 [1]. Additionally, it may occur as part of a complex elbow dislocation or fracture, as seen in Monteggia fractures [2]. While traumatic radial head dislocation is more common in adults, it can be particularly challenging to identify in children, often requiring a high level of clinical suspicion [3].

If left undiagnosed and untreated, chronic radial head dislocation can lead to persistent elbow pain, stiffness, and a limited range of motion. This can result in secondary degenerative arthritis affecting both the elbow and the distal radioulnar joint [4]. Consequently, this necessitates complex interventions in the future, usually requiring open rather than closed reduction. To preserve normal elbow function, maintaining elbow joint congruency and achieving proper radial head reduction are crucial.

The specific mechanism behind isolated radial head dislocation remains unclear [5]. To our knowledge, there have been no previous reports in the literature of isolated lateral radial head dislocation. This case report has been conducted following the SCARE 2023 updated guidelines [6].

2. Case presentation

A 5-year-old boy presented to the emergency department after an unwitnessed fall onto his left hand at home. His parents were concerned about his persistent pain, swelling at the left elbow, and his reduced ability to move the elbow 3 hours post-injury. The child had no history of similar incidents or other injuries.

Upon physical examination, mild swelling was observed around the left elbow, with no pinpoint tenderness over the forearm or wrist (Fig. 1). His elbow movement was limited during pronation and supination, and he was unable to flex or extend his elbow due to pain. Neurological examination revealed intact anterior and posterior interosseous, ulnar, and median nerves. The patient's peripheral pulses were palpable, and he could move his fingers. Additionally, he has no known congenital abnormalities, including collagen defects or genetic mutations.

Fig. 1.

Photograph illustrating pronounced swelling and visible deformity of the left elbow post-traumatic injury.

Radiographs of the elbow from various angles revealed an isolated lateral radial head dislocation without fractures in the olecranon, coracoid, or supracondylar areas. The radius and ulna appeared intact (Fig. 2A, B, C). The proximal and distal radioulnar joints showed no signs of instability, and the ulnar bow sign was negative.

Fig. 2.

A, B, C: X-ray images of the left elbow in anteroposterior (A and C) and lateral (B) views displaying isolated lateral dislocation of the radial head, with integrity of the olecranon, coracoid, and supracondylar regions and no accompanying fractures of the radius and ulna with minimal overlying soft tissue swelling.

After discussing treatment options with the caregivers, including the possibility of open reduction should closed reduction fail, we decided to perform a closed reduction under anesthesia, with written informed consent obtained from the patient's father.

The closed reduction was successfully achieved by applying simple traction along the radius' axis, slight supination, a small valgus force at the elbow joint, and pressure on the radial head. Serial fluoroscopy images post-reduction showed proper alignment with no signs of instability under valgus and varus stresses, nor during flexion and extension. Full active range of motion was restored, though mild residual swelling remained. A long-arm cast was placed in supination, 10 degrees of flexion, and valgus molding to insure stability of reduction and prevention of re-dislocation.

Following the successful reduction of the dislocation, confirmed by fluoroscopy imaging (Fig. 3), the patient's recovery was carefully monitored through a series of follow-up X-rays. One-week post-operation, these images indicated that the reduction of the radial head was still well-maintained, prompting continuous observation. By the three-week follow-up, X-rays continued to show a stable position of the radial head, allowing for the removal of the cast and the initiation of range of motion exercises.

Fig. 3.

Post-reduction fluoroscopy images of the left elbow in anteroposterior (A) and lateral (B) views showing correct alignment of the radial head with cast immobilization.

At the fourth-week follow-up, the patient demonstrated improved elbow mobility, achieving a flexion range of motion from 5 to 50 degrees and full pronation/supination capabilities. Subsequently, targeted physical therapy sessions were initiated and aimed at further enhancing joint function and strength. The therapy proved effective, and by six weeks post-operation, the patient had achieved full range of motion.

At the final 12-week follow-up, the patient had successfully maintained full range of motion and had resumed normal activity levels without any functional limitations. There were no complaints of pain nor discomfort, and the patient experienced no subsequent episodes of dislocation. The successful recovery highlighted the efficacy of the surgical intervention and post-operative rehabilitation plan, resulting in optimal functional restoration of the left elbow.

3. Discussion

To our knowledge, this case represents the first instance of a “pure post-traumatic isolated lateral radial head dislocation”. In 2014, Bradley et al. described an irreducible post-traumatic anteromedial radial head dislocation in a 5-year-old girl that could not be corrected through closed reduction, necessitating successful open reduction [7].

Accurate diagnosis of acute radial head dislocation hinges on precise history-taking, thorough physical examination, and plain radiographic films. Patients typically present with elbow pain and an unwillingness to move it following a fall. While physical examination at this young age group might not always be practical, these patients often exhibit elbow swelling and limited range of motion. Elbow plain radiographs with appropriate views are crucial in cases of suspected elbow or forearm injury. Differentiating between various radial head injuries such as congenital dislocation, chronic dislocation, or acute subluxation is essential [7]. For instance, congenital radial head dislocation typically shows a convex radial head and a hypoplastic, flattened capitellum on radiographs, indicative of dysmorphic changes [8].

A high index of suspicion and careful examination of radiographs are mandatory, as these injuries can be easily missed or misdiagnosed. In a 1999 study by Weisman et al., involving 110 children, the diagnosis of radial head dislocation was delayed in 10 cases [9]. Eight of these cases were initially missed, and in two instances, the dislocation recurred days after a successful initial reduction. These delayed diagnoses were attributed to the spontaneous reduction and subsequent redislocation of the radial head [9]. Studies have demonstrated that the presence of a fat-pad sign on radiographs in children with elbow injuries is indicative of occult intracapsular fractures of the humerus, radius, or ulna [[10], [11], [12]]. Weissman et al. [9] and Kohn et al. [10] further noted that both spontaneous and manipulative reductions of dislocations could also be associated with the fat-pad sign. Consequently, a thorough radiographic assessment of the radiocapitellar joint, utilizing the radiocapitellar line, is recommended for children presenting with elbow and forearm injuries, both initially and after the successful removal of the cast [9]. This highlights the crucial role of proper assessment through adequate radiographs at both the initial presentation and during follow-up. In our case, a prompt diagnosis was achieved through radiographic assessment at the initial presentation, after reduction, and during serial follow-ups.

The commonly used maneuver for reducing anterior radial head dislocation is supination with flexion, where a click indicates successful reduction into the annular ligament [13]. Sometimes, simple positioning of the patient's arm during imaging can lead to reduction. However, the specific mechanism of injury and dislocation pattern dictates the required maneuver. In our case, to reduce lateral radial head dislocation, simple traction along the radius's axis, slight supination, and a valgus force at the elbow joint were necessary. Sometimes, mild pressure over the radial head aids in reduction.

The injury mechanism ranges from partial annular ligament tear to temporary radiocapitellar joint distraction during extreme pronation. Typically, acute traumatic radial head dislocations indicate direct elbow injury causing annular ligament damage [13]. In our case, the unwitnessed home fall led us to hypothesize an annular ligament tear due to a pronated forearm, causing lateral radial head dislocation.

Yasuwaki et al. reported a case of an isolated lateral radial head dislocation in a 9-year-old boy, notable for its lack of an associated ulna fracture. The patient had a pre-existing condition of approximately 7 degrees of cubitus varus from an old supracondylar fracture incurred at the age of 2, which the authors identified as a contributing factor to the dislocation [14]. In this case, the dislocation was addressed with a closed reduction, positioning the forearm in flexion and supination, and subsequently immobilizing it at 90 degrees of both flexion and supination using a plaster cast [14]. By contrast, in our case report, we detail an isolated radial head dislocation that was managed with a reduction maneuver involving extension of the extremity, and notably, there were no pre-existing anatomical variations that could predispose to such a dislocation.

Moreover, Takami et al. detailed a case involving an isolated pediatric posterolateral dislocation of the radial head, which was treated using a technique involving flexion and supination of the forearm, combined with direct pressure over the radial head. The forearm was then immobilized at 90 degrees of flexion and supination. The underlying pathophysiology of this dislocation remains unclear; it is speculated that it might be due to the inherent flexibility of a child's ulna, which allows for bending without fracturing – a characteristic not observed in our case [15].

Shelton et al. reported a case of isolated medial head dislocation requiring open reduction due to a bony block of the closed reduction by the coronoid, highlighting potential impediments to closed reduction like the biceps tendon, joint capsule, brachialis muscle and/or annular ligament [16,17]. In our case, the closed reduction was performed smoothly and did not necessitate an open procedure. Sasaki et al. described an anterior head dislocation, the most common type of isolated radial head dislocation, associated with a transposed biceps tendon [18]. Therefore, if an increase in the radiocapitellar distance is observed following an attempted closed reduction, it should prompt the use of an MRI to investigate the possibility of any transposed soft tissue structures.

4. Conclusion

In conclusion, when evaluating an isolated post-traumatic radial head dislocation, it's crucial to thoroughly analyze both radiological and clinical parameters. If there's any indication of suboptimal reduction due to transposed bony or soft tissue structures, additional imaging and consideration for open exploration and reduction are warranted. This case documents the first instance of a lateral isolated radial head dislocation, a phenomenon previously unreported. Closed reduction remains the preferred treatment method, provided there are no obstructions from bone or soft tissue.

Consent for publication

Written informed consent was obtained from the patient's parents/legal guardian for publication and any accompanying images. A copy of the written consent is available for review by the Editor-in-Chief of this journal on request.

Ethical approval

This is a case report. Our institutional Review Board has confirmed that no ethical approval is required.

Funding

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

Author contribution

All authors have significantly contributed to the design, execution, and writing of the study. They have reviewed and confirmed the accuracy of the entire manuscript, and have agreed to its submitted form.

Guarantor

Dr. Rachid Haidar.

Research registration number

Not applicable.

Conflict of interest statement

None.