First evidence of a bipartite medial cuneiform in the hominin fossil record: a case report from the Early Pleistocene site of Dmanisi

Tarsals from the Sima de los Huesos Middle Pleistocene site (Atapuerca, Burgos, Spain)

Here, we provide a complete, updated, and illustrated inventory, as well as a comprehensive study, of the tarsals (rearfoot) recovered from the Middle Pleistocene site of Sima de los Huesos (SH, Atapuerca, Spain) in comparison to other Homo comparative samples, both extant and fossil. The minimum number of individuals (MNI) estimated from the tarsals has been established as 15, which represents 51.7% of the 29 dental individuals identified within the SH sample. Within the SH hominin foot sample, an exclusive combination of primitive or plesiomorphic and derived or autapomorphic traits can be observed when compared with other Homo individuals/populations. Other characters are shared among SH hominins and Neandertals that might represent shared derived or autapomorphic traits for this evolutionary line, and most are likely related to robusticity (e.g., rectangular-like trochlea of the talus, broad calcanei, broad naviculars, and short lateral cuneiforms). Additionally, we observed some exclusive autapomorphic traits in the SH tarsal sample (e.g., narrow head of the talus and short intermediate cuneiforms). A few exclusive traits in SH tarsal remains are even more robust than in Neandertals (e.g., broad lateral malleolar facet in talus, more projected sustentaculum tali, and broad medial cuneiform). These traits could suggest a slightly higher level of gracilization in the tarsal bones of Neandertals compared to the SH sample that is also supported by other anatomical postcranial skeleton elements. Additionally, some paleobiological inferences are made in relation to body size (stature and body mass) and some associations are proposed within the SH sample. In conclusion, the morphology of the SH tarsi confirms an evolutionary relationship of sister groups between this population and Neandertals, probably representing a morphotype similar to the Neandertal ancestors.

Bipartite medial cuneiform: magnetic resonance imaging findings and prevalence of this rare anatomical variant

OBJECTIVE

To describe the imaging features of bipartite medial cuneiform and to determine the prevalence of this rare anatomical variant in a large group of patients that were evaluated by magnetic resonance imaging (MRI) of the foot.

MATERIALS AND METHOD

Seven hundred and fifty-one patients that underwent MRI of the foot from May 2016 to December 2018 were included in the study (mean age 49 years; 540 females; 211 males). All MRIs were retrospectively analyzed to identify bipartite medial cuneiform. For patients with bipartite medial cuneiform, we analyzed partial and complete bipartition, the type of articulation (synchondrosis, syndesmosis, or a combination of these two), and stress changes related to abnormal motion (i.e., subchondral cysts and sclerosis). Bone marrow edema-like signal, diastasis in the cleavage plane, concomitant fractures, and the presence of the E-sign were also evaluated.

RESULTS

Nine feet from six patients presented bipartite medial cuneiform on the MRI. Six and three feet exhibited complete and partial bipartition. All patients were referred for MRI because of midfoot pain, of which two had history of trauma prior to imaging. Stress changes related to abnormal motion were observed in three feet (34%), all with complete bipartition. Bone marrow edema-like signal was recorded in five feet (55%) and diastasis in one foot (11%). No fractures were present in the bipartite medial cuneiform. All patients had E-signs.

CONCLUSION

Bipartite medial cuneiform is a rare anatomical variant occurring in 0.79% of patients who underwent foot MRI in this study. It is important to be aware of this variant as it is a cause of midfoot pain. Being familiar with the E-sign helps identify and differentiate it from a fracture.

Symptomatic Bipartite Medial Cuneiform: Report of Five Cases and Review of the Literature

Bipartition of the medial cuneiform is a well-described but rarely seen anatomic variant. The majority of literature focuses on anatomic description and incidents based on studies of archeological collections. Symptomatic cases can be overlooked or misdiagnosed initially given the vague complaint of pain either chronic in nature or following an acute injury that could result in a myriad of foot conditions. Treatment ranges from orthotics, immobilization, injection therapy, and surgery. Presented here is a series of 5 cases treated successfully with conservative and surgical measures.

LEVELS OF EVIDENCE

Therapeutic, Level IV.

Bipartite Medial Cuneiform: Case Report and Retrospective Review of 1000 Magnetic Resonance (MR) Imaging Studies

Objective. To present a unique case report of a Lisfranc fracture in a patient with a bipartite medial cuneiform and to evaluate the prevalence of the bipartite medial cuneiform in a retrospective review of 1000 magnetic resonance (MR) imaging studies of the foot. Materials and Methods. Case report followed by a retrospective review of 1000 MR imaging studies of the foot for the presence or absence of a bipartite medial cuneiform. Results. The incidence of the bipartite medial cuneiform is 0.1%. Conclusion. A bipartite medial cuneiform is a rare finding but one with both clinical and surgical implications.