Unilateral non-osseous calcaneonavicular coalition: report of a Portuguese archeological case

Abstract This paper details an unusual morphology detected in two right foot bones, the calcaneusand navicular bone, of an adult female skeleton exhumed from the Late Roman cemetery of Miroico(Sintra, Portugal). This anomaly seems to represent a case of unilateral non-osseous calcaneonavicularcoalition. Tarsal coalitions are anatomical anomalies occasionally described in clinical and rarely in ar-cheological samples. The present case appears to be the second earliest case reported of non-osseouscalcaneonavicular coalition for European osteological samples and adds to the very few archeologicalcase descriptions available.Key words:non-osseous calcaneonavicular coalition, Late Roman, Portugal Introduction Tarsal coalitions (TCs) are rare foot anomalies consistingof the bridging between two or more tarsal bones (Ruhli etal., 2003; Solomon et al., 2007). This union can further beclassified into fibrous (syndesmosis), cartilaginous (syn-chondrosis) or osseous (synostosis) coalitions (O’Rahilly,1953; Percy and Mann, 1988; Newman and Newberg, 2000;Ruhli et al., 2003). In osteoarcheological material it is diffi-cult to establish the differences between fibrous and cartilag-inous coalition, so usually they are join in non-osseous TC(Regan et al., 1999; Silva, 2005). Although most coalitionsare congenital, due to an unif actorial autosomal dominant in-heritance pattern with high or nearly full penetrance(Plotkin, 1996; Bohne, 2001; Newman and Newberg, 2000;Scheuer and Black, 2000; Ruhli et al., 2003), they also canoccur secondary to degenerativ e joint disease, inflammatoryarthritis, trauma, tumour, inf ection, and clubfoot deformities(Percy and Mann, 1988; Bohne, 2001). Calcaneonavicular coalitions (CNC) and talocalcaneal co-alitions are the most commonly reported TCs. Other TCs,such as talonavicular, cuneocuboid, cuneometatarsal, calca-neocuboid, and cubonavicular, are much rarer. The first au-thor to recognize TCs seems to be Buffon in 1769 (www.buffon.cnrs.fr). Some years later, Cruveilhier described ana-tomically osseous unions of several foot bones (http://jubil.upmc.fr/sdx/pl/doc-tdm.xsp? id=CH_00000060_d0e60f Gaynor, 1936; Jack, 1954; Brandt,1956; Ernsting, 1956; Heikel, 1962; Wray and Herndon,1963) but descriptions of pale opathological cases, especiallynon-osseous ones, are rare.In 1950, Harris and Beath described a bilateral osseoustalocalcaneal bridge from the Hunterian Collection of thePathological Museum of the Royal College of Surgeons ofEngland. These undated specimens were first prepared byJohn Hunter and most likely came from a dissection roomcadaver (Harris and Beath, 1950). According to Allen (per-sonal communication in Leonard, 1974) these specimensdate from 1760 to 1770. Con cerning paleopathological cases,Harris (1965, p. 1662) documented a complete medial non-osseous talocalcaneal bridge in the left foot of an adult indi-vidual from the Mayan civilization from Guatemala recov-ered by the Museum of the University of Pennsylvania. Acomplete osseous right and a non osseous left talocalcanealcoalition in a pre-Columbian male adult Indian skeletonfrom Ohio were described by Heiple and Lovejoy (1969). Both findings are dated around 900–950 AD. Calder andCalder (1977) described a unilateral osseous talocalcanealcoalition in the right foot of an adult male skeleton excavat-ed from an Anglo-Saxon cemetery at Updown in Kent (En-gland). Anderson (1995) published a case of bilateral non-osseous cubonavicular bridging associated with bilateralmetatarsal-cuneiform III defect in an adult male (SK31) ex-humed from an Iron Age site in Kent. Another rare TC, anaviculocuneiform I coalition in the right foot (left foot wasabsent) was described in a 14–17 year old individual of un-known sex from the prehistoric site of Farm Hamilton, Lim-poro River Valley, South African (Boshoff and Steyn,2000). Case (2000) reported seven CNCs (2%) detected in asample of 343 white individuals of the Terry Collection and