Radial neck fracture or Monteggia equivalent lesion: delayed radial head subluxation in an adolescent and review of literature

BACKGROUND: Monteggia equivalent lesion represents a series of combined elbow and forearm injuries that resemble typical Monteggia fracture either in presentation or mechanism. The term has gradually evolved since its introduction, as sporadic case reports continued to complement it. The aim of this study was to present a furthermore type of that lesion which no previous study had reported and arouse pediatric orthopedists’ additional awareness of it. CASE PRESENTATION: A 11-year-old girl, whose injury pattern initially appeared to be a mild radial neck fracture with undisplaced proximal ulnar fracture, and without radial head dislocation, was treated with closed reduction and long-arm splint immobilization. Acceptable results were acquired at first-week follow-up, yet dramatic changes turned up 2 weeks later when the dislocated radial head was found. A further reduction to the fracture and joint site only resulted in a subluxated and incongruous radiocapitellar joint on the three-dimensional computed tomography (3D-CT). Then a definitive operation was performed, which involved a Boyd incision, correction of radial head tilting, opening wedge osteotomy of the proximal ulna and proper fixation respectively. And acceptable results were achieved 1 year later. CONCLUSIONS: This case, with occult proximal ulna fracture, angulated radial neck fracture, subsequent radiocapitellar dislocation, and articular incongruity, was deemed as a rare Monteggia type-one equivalent fracture-dislocation variant rather than an ordinary radial neck fracture and it facilitates further understanding and management of the Monteggia fracture.