SAT0439 POWER DOPPLER ULTRASOUND ASSESSMENT OF A1 PULLEY. A NEW TARGET IN PSORIATIC ARTHRITIS?

Background:In the last few years annular pulleys inflammation has been highlighted as a possible key pathogenetic factor in psoriatic dactylitis, first with magnetic resonance imaging (MRI)1, then, in a very recent paper2, with power Doppler (PD) ultrasound (US). However, the prevalence of PD US inflammation of annular pulleys in psoriatic arthritis (PsA) patients compared to rheumatoid arthritis (RA) patients has not been investigated yet.Objectives:To determine the prevalence of PD US findings indicative of A1 pulley inflammation in PsA patients and in controls with RA and to preliminarily investigate the correlation between A1 pulley inflammation and disease activity (DAPSA).Methods:Consecutive patients with PsA and RA were included in this cross-sectional single-centre study. A rheumatologist recorded demographic and clinical data and in the same day another rheumatologist performed the US examination using a MyLab ClassC (Esaote, Genova, Italy) equipped with a 10-22 MHz linear probe. A1 pulleys of fingers 2ndto 5thwere assessed bilaterally adopting longitudinal and transverse scans. The following pathological US findings were recorded: inflammation of the pulley (defined as the presence of PD signal within a thickened pulley) and tenosynovitis of the digital flexor tendons at finger level according to OMERACT definition.Results:Sixty patients were enrolled: 30 with PsA and 30 with RA. Inflammation of A1 pulley was found in 15 out 240 fingers (6.3%) of 8 (26.7%) PsA patients and in 1 out of 240 fingers (0.4%) of 1 (3.3%) RA patients (p<0.01 and p=0.03 respectively). Both pulley inflammation and tenosynovitis were correlated with DAPSA (Rpb=0.56, p<0.01 and Rpb=0.48, p<0.01). In fact, 7 out 8 (88%) PsA patients with at least one inflamed A1 pulley had a moderate/high disease activity score. The regression linear analysis (R2=0.36, adjusted R2=0.31) showed that A1 pulley inflammation was correlated with higher DAPSA scores (β=0.43, p=0.03). No significant association was reported between A1 pulley inflammation and past or current episodes of dactylitis (p=0.09). However, the only current dactylitis assessed showed A1 pulley inflammation.Conclusion:This pilot study demonstrated that ultrasound A1 pulley inflammation, defined as the presence of power Doppler signal within a thickened pulley, is relatively common at patient level in psoriatic arthritis and seems to be characteristic of PsA compared to RA. In psoriatic arthritis patients, a positive significant correlation was found between ultrasound A1 pulley inflammation and disease activity.References:[1]Tan AL, Fukuba E, Halliday NA, Tanner SF, Emery P, McGonagle D. High-resolution MRI assessment of dactylitis in psoriatic arthritis shows flexor tendon pulley and sheath-related enthesitis. Ann Rheum Dis 2015; 74: 185-9.[2]Tinazzi I, McGonagle D, Macchioni P, Aydin SZ. Power Doppler enhancement of accessory pulleys confirming disease localization in psoriatic dactylitis. Rheumatology (Oxford) 2019 [Epub ahead of print].Disclosure of Interests:Gianluca Smerilli: None declared, Edoardo Cipolletta: None declared, Marco Di Carlo: None declared, Andrea Di Matteo Grant/research support from: the publication was conducted while Dr. Di Matteo was an ARTICULUM fellow, Walter Grassi Speakers bureau: Prof. Grassi reports personal fees from AbbVie, personal fees from Celgene, personal fees from Grünenthal, personal fees from Pfizer, personal fees from Union Chimique Belge Pharma, outside the submitted work., Emilio Filippucci Speakers bureau: Dr. Filippucci reports personal fees from AbbVie, personal fees from Bristol-Myers Squibb, personal fees from Celgene, personal fees from Roche, personal fees from Union Chimique Belge Pharma, personal fees from Pfizer, outside the submitted work.

Ultrasonography: the third eye of hand surgeons

High-resolution ultrasonography is an important tool used for the diagnosis and management of inflammatory arthritis of the hand and wrist. This imaging modality has also proven its utility in the evaluation of traumatic lesions of tendons, nerves, annular pulleys, ligaments, and carpal and digital injuries and for detecting foreign bodies and causes of joint locking. One of the great advantages is the possibility of getting an internal image of the involved anatomical structure in axial, coronal, and transversal planes, as well as the option for observing dynamic changes during motion. Examiners may view the structures in the way it suits them best. The objective of this article is to summarize the author’s own experience, to point out the advantage of ultrasonography in diagnosing some selective traumatic and non-traumatic lesions, and to highlight its role in these conditions.

Ultrasonography in the diagnosis and management of non inflammatory conditions of the hand and wrist

High resolution ultrasonography has already become an important tool in the diagnosis and management of inflammatory arthritis of the hand and wrist but lately it has been proven to be the method of choice in the evaluation of traumatic lesions of tendons, annular pulleys, nerves, and ligaments and at the same time in detecting foreign bodies. The objective of this paper is to review and describe the current knowledge on these US findings and to highlight the ultrasonography role in the evaluation of non-inflammatory conditions of the hand and wrist.

Experimental Verification of a Dynamic Finger Model Using Real-Time Data Acquisition

The purpose of this experiment is to create a mathematical model for the function of the annular pulleys of the human finger in flexion. We have assumed that the flexion moment of the middle and proximal phalanges occurs at the proximal and distal ends of the A-2 and A-4 pulleys. The amount of force generated is dependent on the angle of flexion at the adjacent joint, the tension in the tendon and the stiffness constant of the pulley.

Closed Traumatic Rupture of the Flexor Pulleys of a Long Finger Associated with Avulsion of the Flexor Digitorum Superficialis

We report a closed rupture of the second, third and fourth annular pulleys associated with avulsion of the flexor digitorum superficialis tendon in the ring finger of a healthy, 48-year-old patient. It was caused by sudden and violent flexion of the finger and led to a serious impairment of the proximal interphalangeal joint motion, despite physiotherapy and dynamic splinting. The patient was treated surgically, 3 months after the injury, with reconstruction of the second (A2) and fourth (A4) annular pulleys and excision of the distal portion of the superficialis tendon. The final functional result was satisfactory.

Comparative Histology of the Annular and Cruciform Pulleys

Twenty annular and 12 cruciform pulleys were dissected from four unembalmed fresh cadaveric fingers and stained with haematoxylin and eosin, Verhoeff-van Gieson stain for elastin, alcian blue stain for hyaluronic acid, and a separate stain for S-100 to identify chondroid cells. Three distinct layers were identified in both annular and cruciform pulleys: an outer layer of fibrofatty tissue with vascular channels outermost, an inner layer of hyaluronic acid-secreting cells, and a collagen-rich layer in between. Chondroid metaplasia was noted in the inner layer of both types of pulleys. Minimal differences were noted in regard to the elastin fibre content of the pulleys, with slightly more elastin in the annular pulleys, but no other differences were noted.

The Fate of Tendon Grafts Used to Reconstruct the Digital Annular Pulleys

An experimental morphological study on the reconstruction of the digital annular pulleys has been carried out in dogs. The segment corresponding to zones 1 and 2 of the flexor apparatus of the 2nd and 5th digits of the left forepaw was chosen for the experiment. The whole flexor apparatus was resected and a single digital pulley (A 2) was reconstructed, using segments of the animals own deep flexor tendon. A length of silicone rubber tube was used as tendon spacer. The new pulleys showed marked degeneration of the collagen fibres and thinning which increased with time and may be the cause of decrease in strength. A layer of mesothelial cells with secretory properties developed at the interface between the tendon graft and the spacer.

Functional Anatomy of the Vagina Fibrosa of the Flexors of the Fingers

The flexor tendon sheaths of 40 fingers were investigated to determine which classification of the annular and cruciform pulleys seems to be justified. The classification of Kleinert et al. (1981) into five annular and four cruciform pulleys was the most consistent with our results. The constant presence of the mid-phalangeal annular pulleys in zones III and VII shows their major role in preventing the tendons from bow-stringing. The cruciform pulleys seem to allow the tendon sheath to deform during flexion.

Strength of Human Pulleys

The length, breaking strength, and tensile strength of each of the annular fibro-osseous pulleys of digital flexor sheath in ten fresh human cadaver specimens were measured. The first annular pulley and the fourth annular pulley were found to be the strongest, while the second annular pulley was the weakest. The design of artificial pulleys should reproduce the strength of the first annular and fourth annular pulleys. Suggested minimum requirements for the breaking strength of artificial implant pulleys may be made based on these studies.