Anatomical characterization of the too-long anterior process of the calcaneum: a computed tomography scan analysis of 69 feet.

Our work aims to identify and measure the morpho-anatomical characteristics of too-long anterior calcaneal process based on computed tomography scans done in patients with a history of pain and who have experienced repeated ankle sprains. The computed tomography scans of 69 feet were reviewed. These scans were used to calculate (1) the calcaneo-navicular distance; (2) the height, length, and width of the too-long anterior calcaneal process; (3) the length of the calcaneum; (4) the angle of the too-long anterior calcaneal process in the sagittal (anterior-superior angle), axial (anterior-medial angle), and frontal plane. Out of 69 feet, forty-nine were pathological (71%) with abnormalities of the too-long anterior calcaneal process, while the rest (29%) had no morphological abnormalities. The calcaneo-navicular distance was found to be <5 mm (mean: 2.8 ± 1.2 mm) in all pathological feet, which also had significantly reduced calcaneo-navicular distance ( P < 0.001) and longer bone portion distal to the calcaneocuboid tangent ( P < 0.001) in comparison to normal feet. In pathological feet, the mean too-long anterior calcaneal process length was 10.7 ± 1.9 mm; the mean anterior-superior angle was 29.6 ° ± 11.6, the mean angle anterior-medial angle was 40.7 ° ± 8.3, the mean angle frontal plane was 74.2 ° ± 14.1. Similar to a cone or a parallelepiped, the too-long anterior calcaneal process has a complex three-dimensional anatomy, with a superior, medial, and anterior direction. Using the measurements obtained, four different too-long anterior calcaneal process morphotypes could be identified: absence of TLACP, triangular shape, rectangular shape, and coalition (level of evidence III).

The too-long anterior process and osteochondral lesion of the talus: Is there an anatomical predisposition? A case-control study on 135 feet.

INTRODUCTION: The too-long anterior process (TLAP) increases mechanical stress on the hindfoot and could lead to osteochondral lesions of the talus (OLT) by localized hyper-pressure. The purpose of this study is to investigate an association between TLAP and OLT in children. METHODS: This is a retrospective, multicenter, case-control study conducted between 2010 and 2020. The OLT group was compared to a control group (CoG). TLAP is characterized by a distance between the anteromedial process of the calcaneus and the navicular bone (CN) of< 5 mm. RESULTS: Forty-three feets were included in the OLT group and 92 in the CoG. The OLT group had a lower CN distance on CT than the CoG, a median of 2.8 mm versus 3.75 mm (p = 0.002); 86% of patients (37 feet/43) in the OLT group had a CN distance of< 5 mm (OR=3.0 [1.1; 9.5], p = 0.023) compared to 67% in the CoG. DISCUSSION: The OLT group had an increased risk of developing TLAP compared to the CoG. LEVEL OF EVIDENCE: III.