Spine (Phila Pa 1976). 2014 Apr 8. [Epub ahead of print]
11Department of Orthopaedics, Sundsvall and Härnösand County Hospital, Sundsvall, Sweden 2Department of Clinical Sciences, Intervention and Technology, Karolinska Institutet, Stockholm, Sweden 3Department of Orthopaedics, Karolinska University Hospital, Stockholm, Sweden. 4Department of Orthopaedics and Clinical Sciences, Lund University, Skane University Hospital, Malmö, Sweden 5Department of Orthopaedics, Sahlgrenska University Hospital, Gothenburg, Sweden.