title: Abnormal triangular epiphysis causing angular deformity of the thumb.
abstract: OBJECTIVE
  To present a triangular-shaped abnormal secondary ossification center of the distal phalanx causing angular deformity of the thumb and the surgical outcome of corrective closing-wedge osteotomy for this deformity.
  
  
  METHODS
  We treated 6 patients with abnormal triangular epiphysis in the distal phalanx of the thumb, including 3 bilateral cases. The average age was 43 months and there were 2 boys and 4 girls. Of the 9 thumbs intraepiphyseal closing-wedge osteotomy was performed in 5 and proximal phalangeal closing-wedge osteotomy was performed in 4. We measured the deformities in degrees of angulation and the range of motion of the interphalangeal (IP) joint. The average duration of the follow-up period was 27 months after the surgery.
  
  
  RESULTS
  Preoperative angular deformity of ulnar deviation averaged 30 degrees , which was reduced to an average of 12 degrees after osteotomy at the last follow-up assessment. All osteotomies healed and there was no evidence of physeal or articular damage. Interphalangeal joint range of motion did not decrease after surgery in all cases. Patients and parents were satisfied with the results of the surgery, although mild deformity persisted in the interphalangeal joint when in the flexed position after proximal phalangeal osteotomy.
  
  
  CONCLUSIONS
  Abnormal triangular epiphysis causing angled thumb is different from delta bone and can be treated with either intraepiphyseal or proximal phalangeal closing-wedge osteotomy. The intraepiphyseal procedure, however, could achieve better deformity correction regardless of the interphalangeal joint position.
  
  
  METHODS
  Therapeutic, Level IV.
authors.affiliation: Department of Orthopedic Surgery, Seoul National University College of Medicine, Chongno-gu, Seoul, Korea. ghbaek@snu.ac.kr
authors.forename: Goo Hyun
authors.initials: GH
authors.lastname: Baek
authors.forename: Moon Sang
authors.initials: MS
authors.lastname: Chung
authors.forename: Hyun Sik
authors.initials: HS
authors.lastname: Gong
authors.forename: Sanglim
authors.initials: S
authors.lastname: Lee
authors.forename: Young Ho
authors.initials: YH
authors.lastname: Lee
authors.forename: Hyoung Ho
authors.initials: HH
authors.lastname: Kim
mesh_terms: D002675:Child, Preschool; D004838:Epiphyses / Q000002:abnormalities* / Q000601:surgery; D005260:Female; D005384:Finger Joint / Q000502:physiology; D006228:Hand Deformities, Congenital / Q000601:surgery; D006801:Humans; D007223:Infant; D008297:Male; D010027:Osteotomy / Q000379:methods; D016059:Range of Motion, Articular; D013933:Thumb / Q000002:abnormalities* / Q000601:surgery