ECTS Abstracts (2015) 1 P72

Early changes in micro-architectural bone parameters in the development of complex regional pain syndrome type 1 after a distal radius fracture

Frans Heyer1,2, Joost de Jong1,3, Paul Willems4, Rob Smeets5,6, Jacobus Arts4,5, Martijn Poeze1,2, Piet Geusens3,7, Bert van Rietbergen8 & Joop van den Bergh1,9

1Research School NUTRIM, Maastricht University, Maastricht, The Netherlands; 2Department of Surgery, Maastricht University Medical Center, Maastricht, The Netherlands; 3Department of Rheumatology, Maastricht University Medical Center, Maastricht, The Netherlands; 4Department of Orthopedic Surgery, Maastricht University Medical Center, Maastricht, The Netherlands; 5Research school CAPHRI, Maastricht University, Maastricht, The Netherlands; 6Department of Rehabilitation Medicine, Maastricht University Medical Center, Maastricht, The Netherlands; 7Faculty of Medicine and Life Sciences, Hasselt University, Hasselt, Belgium; 8Faculty of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands; 9Department of Internal Medicine, VieCuri Medical Center Venlo, Venlo, The Netherlands.

Complex regional pain syndrome type 1 (CRPS-1) is a clinical syndrome characterised by pain that is disproportionate to the inciting event (e.g. a fracture), oedema, decreased function, changes in skin colour and bone loss. Although Südeck proposed an inflammatory origin over a century ago, the pathophysiology is still unknown. Current hypotheses include neurological, vasomotor and immune dysfunctions. In two recently published papers we reported that the healing process of stable distal radius fractures can be assessed using high-resolution peripheral quantitative computed tomography (HR-pQCT) in combination with finite element analysis (FEA). A 54-year old postmenopausal patient who was included in this study developed CRPS-1 during fracture healing. HR-pQCT scans of the fractured wrist of this patient were performed at 12, 23, 45 and 86 days and 26 months post-fracture according to the study protocol and showed a remarkable decrease in trabecular density, first detected six weeks post-fracture (fifth percentile), along with a decrease in trabecular number, which persisted at 26 months. There was an initial temporary strong increase in markers of bone formation and resorption. Surprisingly, the coronal cross-sections revealed dramatic resorption of trabecular bone proximal, but not distal of the fracture line. In contrast, the cortical region healed normally as the fracture gaps were bridged and cortical thickness increased. This resulted in restoration of bone stiffness as estimated with FEA at 26 months similar to patients without CRPS-1. These results, though from a single patient, illustrate the possible role of HR-pQCT in the early identification of CRPS-1 related bone loss and could identify patients at risk for developing CRPS-1. The anatomical localisation of trabecular bone changes in the diaphysis and proximal of the fracture site suggests involvement of the vasculature of the nutrient artery in the resorption process.

Disclosure: P.C. Willems is a board member of the Dutch Spine Society (association of spine surgeons). J.J. Arts is a board member of workgroup Biotechnology of the Dutch Orthopedic Association (NOV). B. van Rietbergen is a consultant for Scanco Medical AG. This work was supported by the Weijerhorst Foundation (grant number WH2).