Inveterate Section of Deep Flexor in Pediatric Hand, Periosteum Clues.

Diagnostic delay in flexor tendon injuries is common in pediatric patients, and age influences both recovery and postoperative management. We report the case of a three-year-old girl who presented with the inability to flex the distal interphalangeal joint of the left third finger, two months after the digit became entrapped in a chair. Ultrasonography revealed cortical ossification of the middle phalanx compressing the flexor tendon, without clear evidence of discontinuity. Surgical exploration was undertaken due to a strong clinical suspicion of flexor digitorum profundus rupture, revealing an old laceration with fibrotic changes. The proximal tendon stump was reattached to the distal phalanx using a pull-out suture; the bone lesion was left untreated. At six weeks, radiographs demonstrated ossification consolidation, consistent with periosteal injury secondary to a middle phalanx fracture. This case highlights the importance of examination under sedation for pediatric hand injuries. Periosteal injury can result in callus formation, and after tendon repair, postoperative immobilization may need to be prolonged compared with adult patients.