Bifascicular nature of the flexor digitorum profundus and flexor pollicis longus tendons: forgotten anatomical characteristics rediscovered with US imaging.

OBJECTIVES: To demonstrate the bifid configuration of the flexor digitorum profundus (FDP) and flexor pollicis longus (FPL). METHODS: In the first part of this study, 20 digits from 4 cadaver hands were dissected and analyzed using anatomical and histological slices. The second part of the study was carried out over a 12-month period starting in August 2018. It was a prospective US imaging study of 300 digits from 30 healthy participants performed by two radiologists in a double-blinded manner. This study focused on two items: tendon shape and whether a central septum separated the two hemitendons. Descriptive statistics were calculated along with the inter-rater reliability. RESULTS: In 100% (300/300) of fingers and thumbs, the FDP and FPL tendons were made up of two parallel bundles arranged side by side, with a central vertical septum between these two hemitendons, starting at the head of the proximal phalanx (PP) and continuing distally. This central septum was always present starting at the proximal third of PP for the FDP of the index, middle, and ring fingers. The septum was more difficult to identify in the thumb and little finger. Cohen's kappa indicated near perfect agreement when all digits were considered together (≥ 0.9), and substantial agreement for the thumb (0.71) and for the little finger (0.82). CONCLUSIONS: With US imaging, the bifascicular nature of the FDP and FPL tendons is easy to see, as these tendons have a double-barreled configuration starting at the head of the proximal phalanx. KEY POINTS: •Analysis of anatomical slices of the hand tendons found a bifascicular appearance of the flexor digitorum profundus and flexor pollicis longus tendons starting at the head of the proximal phalanx. •This distinct feature of two hemitendons arranged side by side was seen in 100% of tendons we examined with US. It is associated with a vertical central septum that causes anisotropy. •Awareness of this "forgotten" anatomical detail has practical implications when interpreting images generated by latest-generation US systems and during surgery on hand flexor tendons.

Bone age estimation based on multislice computed tomography study of the scapula.

Progress in medical imaging has opened new areas of research in forensic anthropology, especially in the context of the study of bone age assessment. The study of bone age has become a useful tool for age estimation at death or age of young adult migrants in an anthropological context. We retrospectively evaluated multislice computed tomography (MSCT) explorations focused on scapulae of 232 individuals (123 males; 109 females) aged between 8 and 30 years old. Computed tomography (CT) scans were viewed in axial and multiplanar reconstructed images using OsiriX 5.9 (64 bit)®. The ossification centers of the scapula studied were as follows: acromial, sub-coracoid, glenoid, coracoid, coracoid apex, and inferior angle epiphyses. Fusion status was scored based on a five-stage system (stage 1: no ossification, stage 2: visualization of an ossification center, stage 3: partial ossification, stage 4: full ossification associated to an epiphyseal scar, and stage 5: full ossification without epiphyseal scar). Intra-observer variability was excellent, and inter-observer variability was good, demonstrating the reliability of this MSCT staging system. The fusion of scapular ossification centers was statistically associated with age (p < 0.001) but not with sex (p > 0.05). In conclusion, MSCT of the scapula is an efficient method for age assessment, which is complementary to preexisting methods particularly for specifying the 18-year threshold. Further studies with larger groups are needed to support our results.