Delayed Extensor Pollicis Longus Rupture after Distal Radius Fracture in a Pediatric Patient

Within the adult population, rupture of the extensor pollicis longus (EPL) is a well-described complication after distal radius fractures, with an estimated frequency of 0.9 to 5%,[1] [2] [3] and most commonly occurs between 3 and 12 weeks after the fracture.[2] Distal radius fractures are the most common fracture in the pediatric population, accounting for 25 to 43% of all pediatric fractures,[4] and are primarily treated nonoperatively with minimal complications.[4] Despite the high incidence of these fractures in the pediatric population, rupture of the EPL is very rare in this patient cohort. Case reports in pediatric patients have described EPL rupture in significantly displaced fractures.[1] [5] In this report, we describe the first case report to our knowledge of a delayed EPL tendon rupture in a pediatric patient following a minimally displaced distal radius fracture.

A 14-year-old male patient presented with a closed injury to his bilateral wrists following a fall while playing basketball. Radiographs were obtained that revealed nondisplaced bilateral distal radius fractures. He was treated in a cast bilaterally for 6 weeks by his local orthopaedist. After the casts were removed, the patient returned to his regular activities. Three weeks later, the patient noted the inability to extend his left thumb. He did not describe pain with the incident and denied repeated trauma to the wrist. A radiograph was obtained that showed a well-healed distal radius fracture with increased callus formation dorsally ([Fig. 1]). EPL tendon rupture was confirmed clinically, and with ultrasound. Surgical exploration was performed that revealed an attritional rupture of the EPL tendon. Fracture callus and bony spicules were present within the floor of the third extensor compartment.

Fig. 1 Anteroposterior and lateral radiographs after extensor pollicis longus rupture revealing extensive dorsal callus overlying the healed fracture site.

As previously stated, delayed rupture of the EPL tendon is a known complication after distal radius fractures in adults, with an estimated frequency of 0.9 to 5% in adults.[1] [2] [3] However, delayed EPL rupture after minimally displaced distal radius fractures is rare in children.[1]

The exact mechanism of EPL rupture after distal radius fracture is speculative. Multiple etiologies have been suggested, including mechanical irritation and local ischemia to the tendon. Other reports have suggested the tendon may be injured directly on the fracture fragment or during reduction, although this is not likely in the case of a minimally displaced fracture without a reduction being performed. Attritional rupture in this case is more likely due to a relatively avascular portion of the EPL near Lister's tubercle. Previous studies have shown bleeding inside the tendon sheath can cause significant effusion leading to microvascular disruption of the tendon after minimally displaced distal radius fractures. Additionally, a bony prominence of fracture callus was noted in the floor of the third extensor compartment that likely caused mechanical irritation. Therefore, we propose EPL rupture in this patient was secondary to microvascular disruption of the tendon combined with mechanical irritation from fracture callus.

In conclusion, EPL rupture after distal radius fractures in adults is an infrequent, but well described, complication. To our knowledge, this is the first case report of an EPL rupture after a minimally displaced distal radius fracture in a pediatric patient. Therefore, this requires a high clinical index of suspicion to diagnose but should not be missed.

Publication History

Article published online:
13 April 2021

• References

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