Naviculo-cuneiform I coalition: Evidence of significant differences in tarsal coalition frequency

The relatively large number of naviculo-cuneiform I cases reported from Japan, and their rarity in American and European clinical literature, suggests that populations may vary in tarsal coalition frequency [Kumai T, Tanaka Y, Takakura Y, Tamai S. Isolated first naviculocuneiform joint coalition. Foot Ankle Int 1996;17:635-40]. Our objective is to test for significant differences in naviculo-cuneiform I coalition frequency between geographically distinct populations. Skeletal remains from one African sample and two samples of European ancestry were analyzed. Fisher's Exact tests [Uitenbroek DG. Fisher Exact [online]. 2000 [cited 2004 March 10]. Available from: URL: http://home.clara.net/sisa/fisher.htm] were employed to identify sample differences (α = 0.05). Six cases of naviculo-cuneiform I coalition were identified in the African sample; no cases were found in the Danish or American samples. Naviculo-cuneiform I coalition was significantly more prevalent in South African Bantu than in medieval Danes (p = 0.014; 1 − β = 0.70) or the combined sample of European ancestry (p = 0.003; 1 − β = 0.83). Given the sample sizes studied, a statistical difference was not found between the American and South African samples (p = 0.087; 1 − β = 0.52). Population differences in naviculo-cuneiform I coalition are clinically relevant since tarsal coalition may be symptomatic and associated with other abnormalities. Carpal coalition and transposition of the maxillary canine and first premolar were each found to be significantly associated with naviculo-cuneiform I coalition.