Entrapment of the flexor digitorum profundus (FDP) tendon following radius and ulna midshaft paediatric forearm fractures has been reported rarely in the literature. To date, 19 cases have been described. A characteristic fracture pattern, persistent cortical defect at the fracture site and flexion contracture not responsive to hand therapy are all hallmarks of the condition. We present a case along with a review of the literature. A 12-year-old boy underwent exploration of a primary right open radius and ulna fracture site 22 months following initial open reduction and titanium elastic nail system (TENS) fixation. The little finger FDP tendon was found interposed between the ulna bone with a significant defect in the cortical surface of the ulna, correlating with a lucency identified on plain radiograph preoperatively. Removal of all interposed tissue, debridement of the bone edges and Pulvertaft tendon weave of the FDP of the little finger to the ring finger were performed. The patient recovered full upper limb function. Clinicians should be vigilant to identify this complication when managing patients with forearm fractures. A thorough clinical examination pre-and post-open or closed forearm fracture reduction should be performed to ensure early recognition of this rare complication. If the tenodesis effect and post-operative adhesions cannot be adequately released by therapy, interposition of the tendon at the fracture site should be considered as a differential diagnosis. If the complication is suspected, early operative intervention should be performed to ensure optimal fracture healing and restoration of function.