title: Van neck disease: osteochondrosis of the ischiopubic synchondrosis.
abstract: BACKGROUND
  Van Neck disease (VND) is a benign skeletal abnormality of children involving a hyperostosis of the ischiopubic synchondrosis (IPS) seen on radiographs. Patients typically complain of vague groin or buttock pain. Few descriptions of this disorder exist and it easily can be mistaken for other entities, particularly osteomyelitis or tumor. It is often considered a diagnosis of exclusion as laboratory values are usually normal and routine radiographic workup may be nonspecific. We present a series of patients with VND and we compare them with a similar cohort of patients with acute hematogenous ischiopubic osteomyelitis (IPOM). We also draw attention to a new magnetic resonance imaging (MRI) finding that seems to support the theory that VND results from an excessive pull of the hamstring tendon on the ischial tuberosity.
  
  
  METHODS
  All patients presenting to our institution for the evaluation of groin or buttock pain during an 8-year period (August 2001 to May 2009) were retrospectively identified. Twenty-five patients demonstrated enhancement of the ischiopubic area on MRI. Five patients were excluded for lack of sufficient laboratory data. Ten patients were diagnosed and treated with culture proven IPOM and 10 patients were diagnosed with VND and treated with observation. History, physical examination, laboratory values, plain films, and MRI were compared to identify the diagnostic differences between these 2 entities.
  
  
  RESULTS
  The age range for both groups was between 4 and 12 years old. The mean age was 7 years for the VND group and 7.6 years for the IPOM group. The VND group tended to have more distinct hyperostosis of the IPS on radiographs. The factors that were characteristic of IPOM were: fever, limp, pain with rotation of the hip, elevated erythrocyte sedimentation rate, elevated C-reactive protein (CRP), and positive blood culture. MRI showed obvious myositis, abscess, and free fluid surrounding the IPS in all patients with IPOM, but not in the VND patients. Enhancement was seen in the ischial tuberosity, near the hamstring origin, in nearly all Van Neck patients; this pattern of edema may support stress reaction and callus formation as a mechanism for IPS hypertrophy.
  
  
  CONCLUSIONS
  VND is a little-known entity characterized by enlargement of the IPS and should be in the differential of groin or buttock pain in children from the age of 4 to 12 years. IPOM may present similar to VND. Absence of fever, limp, pain with rotation of the hip, elevated C-reactive protein/erythrocyte sedimentation rate, and negative blood culture can help to differentiate VND from IPOM. Presence of marrow edema around the IPS and in the ischial tuberosity, along with absence of surrounding myositis, abscess, and free fluid on MRI are reliable findings that can confirm the diagnosis of VND. The absence of these characteristics can eliminate the need for admission, aspiration, or biopsy. The treatment for VND is observation and the symptoms should abate over time with expectant management.
  
  
  METHODS
  Comparative Diagnostic, Level IV.
authors.affiliation: Department of Orthopaedic Surgery, Pinnacle Health System, Harrisburg, PA, USA. wait.adam@yahoo.com
authors.forename: Adam
authors.initials: A
authors.lastname: Wait
authors.forename: Trevor
authors.initials: T
authors.lastname: Gaskill
authors.forename: Zahir
authors.initials: Z
authors.lastname: Sarwar
authors.forename: Michael
authors.initials: M
authors.lastname: Busch
mesh_terms: D002648:Child; D002675:Child, Preschool; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D007512:Ischium / Q000002:abnormalities*; D007596:Joints / Q000002:abnormalities*; D008279:Magnetic Resonance Imaging; D008297:Male; D055034:Osteochondrosis / Q000151:congenital* / Q000175:diagnosis; D011630:Pubic Bone / Q000002:abnormalities*