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The aim of this study was to identify the prevalence and distribution of sesamoid bones in the hand using digital tomosynthesis (DTS) in comparison to previous studies. Using conventional radiography (CR) and DTS, hand images (81 left and 100 right) taken at a tertiary hospital were retrospectively reviewed. The sesamoid bones were identified in the interphalangeal (IP) and metacarpophalangeal (MCP) joints of the thumb (I), and in the distal interphalangeal (DIP) and metacarpophalangeal (MCP) of index (II), middle (III), ring (IV), and little (V) fingers. Differences in number of sesamoid bones detected on CR and DTS were analyzed. Sesamoid bones were observed in MCP I (100%), MCP II (46%), MCP III (2%), MCP IV (2%), MCP V (53%), and IP I (53%) on CR. Using DTS, sesamoid bones were found more often in MCP I (100%), MCP II (54%), MCP III (2%), MCP IV (1%), MCP V (59%), and IP I (75%). Differences in the mean number of sesamoid bones detected on CR and DTS were statistically significant. Sesamoid bones in DIP joints were frequently observed on DTS, but rarely found on CR. Most sesamoid bones in the hand were detected in MCP I, II, V, and IP I joints, and were more often detected on DTS than CR. DTS is a reliable tool to evaluate bony structures in the hand. Clin. Anat. 30:608-613, 2017. © 2017 Wiley Periodicals, Inc.

In many studies, interest lies in determining whether members of the study population will undergo a particular event of interest. Such scenarios are often termed 'mover-stayer' scenarios, and interest lies in modelling two sub-populations of 'movers' (those who have a propensity to undergo the event of interest) and 'stayers' (those who do not). In general, mover-stayer scenarios within data sets are accounted for through the use of mixture distributions, and in this paper, we investigate the use of various random effects distributions for this purpose. Using data from the University of Toronto psoriatic arthritis clinic, we present a multi-state model to describe the progression of clinical damage in hand joints of patients with psoriatic arthritis. We consider the use of mover-stayer gamma, inverse Gaussian and compound Poisson distributions to account for both the correlation amongst joint locations and the possible mover-stayer situation with regard to clinical hand joint damage. We compare the fits obtained from these models and discuss the extent to which a mover-stayer scenario exists in these data. Furthermore, we fit a mover-stayer model that allows a dependence of the probability of a patient being a stayer on a patient-level explanatory variable.