Sesamoid and accessory bones of the hand--an epidemiologic survey in a Mediterranean population.

The prevalence and distribution of sesamoid and accessory bones in the hands is quite variable between different populations and ethnic groups. However, there are no published data on their distribution in Mediterranean populations. Studies on the validity of radiographic assessment for the presence of these bones are also lacking. A retrospective review of 442 radiographs of adult patients was performed in order to assess the incidence of sesamoid and accessory bones in the hands of a Mediterranean population. Additionally, two independent observers reviewed 174 radiographs and used the Kappa parameter in order to assess the validity of radiographic interpretation of radiographs for the presence of those bones. There was an incidence of 99.5% sesamoid bones (n = 440) in the 1st metacarpophalangeal (MCP) joint, 42.3% in the 2nd MCP joint (n = 187), and 41.1% (n = 182) in the 5th MCP joint. The incidence in the 1st interphalangeal joints was 26.2% (n = 116). The incidence of sesamoid bones in the 1st, 2nd, and 5th metacarpophalangeal joints in a Mediterranean population was found to be similar to that of Arab and Caucasian populations, whereas their prevalence in the 1st interphalageal joint coincided more with Arab populations. Interobserver reliability of the interpretation of radiographs for the presence of sesamoid bones in the hand was good (Kappa > 0.68) in all locations, except for the 1st MCP joint. Further research is warranted to further elucidate the genetic and/or environmental reasons for the differences between those populations.