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.

Extrasynovial ultrasound abnormalities in the psoriatic finger. Prospective comparative power-doppler study versus rheumatoid arthritis.

We prospectively compared power Doppler ultrasound findings in 25 fingers with rheumatoid arthritis (RA) and 25 fingers with psoriatic arthritis (PsA). Erosive synovitis and tenosynovitis were seen in both groups. Extrasynovial changes were found in 21/24 (84%) fingers with PsA versus none of the fingers with RA. Of the 21 PsA fingers exhibiting extrasynovial changes, 15 (15/25, 60%) also had synovial changes. The extrasynovial changes reflected enthesitis or soft tissue inflammation, with the main patterns being capsular enthesophyte, juxtaarticular periosteal reaction, enthesopathy at the site of deep flexor tendon insertion on the distal phalanx, and subcutaneous soft tissue thickening of the finger pad or entire finger. In four fingers, ultrasonograhy showed pseudotenosynovitis, an underrecognized abnormality characterized by diffuse inflammation of the digital soft tissues. Pseudotenosynovitis may play a pivotal role in dactylitis (sausage digit), which is defined as diffuse uniform swelling of the entire finger. Our findings suggest that inflammation of the fibrous skeleton of the finger may lead to the clinical and radiological features that distinguish PsA from RA of the finger.

Percutaneous catheterization of the long bones: experimental study.

The objective of this study was to develop a technique which would permit access to the entire contents of long bones using a minimally invasive approach. Vascular catheterization techniques were used to allow access to the entire marrow cavity through a minimal percutaneous approach. A new device was also developed to reach the epiphysis of the long bone. The study was performed on animal and human anatomical specimens. A percutaneous approach was made through the bone shaft from a remote entry site using principles from endoscopy in an ex vivo experiment. This method may become an alternative technique when a direct approach to lesional sites in long bones is dangerous or impossible. For example, it could be used in cases of preventive cement injections in weakened bones.