Isolated Ring Finger Flexor Digitorum Profundus Entrapment After Closed Reduction and Intramedullary Fixation of Both-bone Forearm Fracture

Abstract

Flexor tendon entrapment after a pediatric forearm fracture is a rarely reported complication that is often diagnosed late. Flexor tendon entrapment is more frequently reported after distal forearm fractures, and possible etiologies include fibrosis secondary to hemorrhage at the fracture site and simple entrapment of the muscle belly.This article describes a case of ring finger flexor digitorum profundus entrapment in a 12-year-old boy with a closed both-bone forearm fracture that was treated with closed reduction and intramedullary nail fixation. Preoperatively, the patient had full flexion and extension of all fingers. The entrapment was noted at the first postoperative follow-up when the patient could fully extend the ring finger proximal interphalangeal joint but was unable to concomitantly extend the metacarpal phalangeal joint. Magnetic resonance imaging and ultrasound were obtained to identify the entrapment site. Intraoperatively, a portion of the flexor digitorum profundus musculotendinous junction was entrapped in the fracture site. After release of the entrapment, the patient gained immediate passive range of motion. Subsequently, the hardware was removed, and the patient healed and regained full ring finger function. To the authors' knowledge, this is the only report of isolated ring finger flexor digitorum profundus entrapment after closed reduction and intramedullary fixation of a pediatric forearm fracture. The authors recommend vigilant physical examination of passive and active range of motion of all digital joints with the wrist in flexion and extension before and after bony manipulation.

Tenodesis Effect Mimicked by Flexor Tendon Entrapment in a Paediatric Midshaft Forearm Fracture: a Case Report and Review of the Literature

“…Flexor tendon entrapment has been reported at different anatomical sites including the phalangeal bones [11,12] and is more commonly reported in distal forearm fractures [6,13,14], compared to MRU fractures. In the case report by Kitridis [14], a similar case is discussed with a more proximal metaphyseal fracture site.…”

“…The ring finger is at increased risk as its muscle fibres arise from the midshaft of the ulna and is therefore intimately associated with a midshaft fracture [15]. Isolated FDS tendon entrapment has been reported after closed reduction and intramedullary fixation, but this is extremely rare as it lies superficial to FDP [6]. Flexor pollicis longus entrapment has also been reported [8].…”

“…8 Plain radiograph at 15 months post-revision surgery associated with high-energy trauma [4] with a number of mechanisms proposed. These include entrapment of the muscle belly with muscle fibrosis secondary to haemorrhage at the fracture site causing progressive contracture until the fracture has healed [3,5]; secondly, entrapment during reduction from a sharp fracture fragment [5]; or thirdly, having the hand in a flexed or closed-fist position at the time of injury [6]. A characteristic fracture pattern has been hypothesized as a short oblique ulna fracture with a spike of the proximal fragment on the anterior cortex [7].…”

Entrapment of the Flexor Digitorum Profundus in the Callus after a Closed Distal Radial Fracture

“…Flexor digitorum profundus tendon entrapment is a rarer reported complication after distal radius fractures; it is more frequently reported after distal forearm fractures, and possible etiologies include fibrosis secondary to hemorrhage at the fracture site and simple entrapment of the muscle belly. 1 , 5 , 6…”

“…Other known complications of the closed reduction of forearm fractures include malunion, refracture, heterotopic ossification, neurovascular insult, compartment syndrome, infection, and soft tissue/nerve entrapment. 5 , 6…”