Rigmor Myran*, Knut Hagen, Sven Svebak, Oystein Nygaard and John-Anker Zwart
* Corresponding author: Rigmor Myran rigmor.myran@ntnu.no
BMC Musculoskeletal Disorders 2011, 12:129 doi:10.1186/1471-2474-12-129