Tendons are commonly affected by MSU crystal deposition in patients with tophaceous gout. The patterns of MSU crystal deposition suggest that biomechanical strain or other local factors may contribute to deposition of MSU crystals.

MSU crystals are frequently present in joints affected by radiographic damage in gout. These findings support the concept that MSU crystals interact with articular tissues to influence the development of structural joint damage in this disease.

Paget's disease is a condition involving focal overactivity of bone cells (osteoblasts and osteoclasts), which can result in significant skeletal morbidity. It is unclear in which bone cells the causative lesion resides. It is managed effectively with potent bisphosphonates, but treatment is difficult if these drugs are contraindicated. We describe a 75-year-old woman with Paget's disease involving the skull who was intolerant of bisphosphonates, so was treated with denosumab. This intervention normalized serum alkaline phosphatase for 4-8 months after each injection and led to some symptomatic improvement. Scintigraphic activity in the lesion was improved but not normalized. We conclude that reduction in RANKL activity by denosumab only partially corrects pagetic activity, indicating that the osteoclast overactivity of Paget's disease is not wholly mediated by RANKL. Denosumab has some clinical utility in Paget's disease and may become a second-line agent in those with contraindications to intravenous bisphosphonates.

IntroductionDual-energy computed tomography (DECT) has potential for monitoring urate deposition in patients with gout. The aim of this prospective longitudinal study was to analyse measurement error of DECT urate volume measurement in clinically stable patients with tophaceous gout.MethodsSeventy-three patients with tophaceous gout on stable therapy attended study visits at baseline and twelve months. All patients had a comprehensive clinical assessment including serum urate testing and DECT scanning of both feet. Two readers analysed the DECT scans for the total urate volume in both feet. Analysis included inter-reader intraclass correlation coefficients (ICCs) and limits of agreement, and calculation of the smallest detectable change.ResultsMean (standard deviation) serum urate concentration over the study period was 0.38 (0.09) mmol/L. Urate-lowering therapy was prescribed in 70 (96%) patients. The median (interquartile range) baseline DECT urate volume was 0.49 (0.16, 2.18) cm3, and change in DECT urate volume was -0.01 (-0.40, 0.28) cm3. Inter-reader ICCs were 1.00 for baseline DECT volumes and 0.93 for change values. Inter-reader bias (standard deviation) for baseline volumes was -0.18 (0.63) cm3 and for change was -0.10 (0.93) cm3. The smallest detectable change was 0.91 cm3. There were 47 (64%) patients with baseline DECT urate volumes <0.91 cm3. Higher serum urate concentrations were observed in patients with increased DECT urate volumes above the smallest detectable change (P = 0.006). However, a relationship between changes in DECT urate volumes and serum urate concentrations was not observed in the entire group.ConclusionsIn patients with tophaceous gout on stable conventional urate-lowering therapy the measurement error for DECT urate volume assessment is substantially greater than the median baseline DECT volume. Analysis of patients commencing or intensifying urate-lowering therapy should clarify the optimal use of DECT as a potential outcome measure in studies of chronic gout.

The presentation of 3-D bone models during a medical consultation can modify cognitive and emotional representations relevant to treatment initiation among people with osteoporosis and might facilitate commencement of bisphosphonate treatment.

We have previously demonstrated that intravenous ibandronate produces high initial response rates in Paget's disease, but the durability of this effect is unknown. It might be expected to be short lived because ibandronate has a low affinity for bone. Here we report long-term follow-up (up to 14 years) of patients from that trial. Twenty-five patients with active Paget's disease [baseline serum total alkaline phosphatase (ALP) ~3 times the upper limit of normal] received either 6 or 12 mg intravenous ibandronate at baseline. There were prompt reductions in ALP following treatment, with normalization in 88%. ALP remained in the normal range in most patients for 20-30 months, but some subjects then showed gradual increases. Three years after ibandronate, before any patients had received additional treatment, ALP was normal in 61%. Six patients maintained normal ALP beyond 6 years without further intervention. Responses to 6 and 12 mg were similar. These results indicate that long-term remissions in Paget's disease can be achieved with bolus delivery of a potent bisphosphonate, even if the drug has a low affinity for bone. Therefore, bisphosphonate retention in bone might not be the only factor determining duration of remission. Intravenous bisphosphonates are likely to produce high drug concentrations within pagetic lesions which might result in cytotoxicity to the pagetic cells, leading to long durations of remission. These findings strengthen the evidence that potent bisphosphonates delivered in a single intravenous dose are a very efficient way to manage this condition.