title: Occult posterolateral rotatory dislocation of the elbow with olecranon fracture in a child: a case report.
abstract: BACKGROUND
  Acute posterolateral rotator elbow dislocation in a child is rare and can be easily misdiagnosed due to immaturity of the epiphysis. This is the first case of occult posterolateral rotator elbow dislocation in combination with an olecranon fracture. We report our experience with this case, which was not diagnosed correctly by plain radiographs.
  
  
  METHODS
  An 11-year-old Asian boy suffered severe pain and swelling of his right elbow after his outstretched arm hit a car dashboard in a motor vehicle accident. Plain radiographs showed only a minimally displaced olecranon fracture and a tiny lateral epicondylar avulsion fracture. However, stress radiographs under general anesthesia revealed severe posterolateral rotatory instability. During surgery, we found that the cartilaginous lateral epicondylar apophysis was much larger than the epicondylar fragment on the radiographs. After the lateral epicondylar osteochondral fragment and lateral collateral ligament complex were fixed, the instability disappeared.
  
  
  CONCLUSIONS
  Our experience with this case shows that it is important to check for instability with pediatric elbow fractures, because a tiny avulsion fracture was able to cause severe posterolateral rotatory instability in a child.
authors.affiliation: Department of Orthopedic Surgery, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka, 565-0871, Japan. takahito-f@hotmail.co.jp.
authors.forename: Takahito
authors.initials: T
authors.lastname: Fujimori
authors.forename: Kohji
authors.initials: K
authors.lastname: Kuriyama
authors.forename: Koji
authors.initials: K
authors.lastname: Yamamoto
authors.forename: Hisao
authors.initials: H
authors.lastname: Moritomo
authors.forename: Hideki
authors.initials: H
authors.lastname: Yoshikawa