The role of the bone in complex regional pain syndrome 1-A systematic review

ObjectiveThe aim of this systematic review was to appraise and analyse the knowledge on bone-related biochemical and histological biomarkers in complex regional pain syndrome 1 (CRPS 1). DatabaseA total of 7 studies were included in the analysis (biochemical analyses n = 3, animal study n = 1, histological examination n = 3). ResultsTwo studies were classified as having a low risk of bias and five studies with a moderate risk of bias. Biochemical analysis indicated an increased bone turnover with increased bone resorption (elevated urinary levels of deoxypyridinoline) and bone formation (increased serum levels of calcitonin, osteoprotegerin and alkaline phosphatase). The animal study reported an increased signalling of proinflammatory tumour necrosis factor 4 weeks postfracture, which did, however, not contribute to local bone loss. Histological examination from biopsies revealed thinning and resorption of cortical bone, rarefication and reduction in trabecular bone and vascular modification in the bone marrow in acute CRPS 1, and replacement of the bone marrow by dystrophic vessels in chronic CRPS 1. ConclusionThe limited data reviewed revealed certain potential bone-related biomarkers in CRPS. Biomarkers hold the potential to identify patients who may benefit from treatments that influence bone turnover. Thus, this review identifies important areas for future research in CRPS1 patients.