Rheumatoid Arthritis and Tenosynovitis at the Metatarsophalangeal Joints: An Anatomic and MRI Study of the Forefoot Tendon Sheaths

Abstract

Background Although tenosynovitis in the hands is associated with rheumatoid arthritis (RA), it is unknown whether tenosynovitis of the forefoot is associated with RA. Purpose To determine the anatomy of tendon sheaths of the forefoot and the relationship between MRI-detected tenosynovitis at metatarsophalangeal (MTP) joints and RA. Materials and Methods Fourteen forefeet of donated bodies were examined at flexor tendons and extensor tendons for the presence and course of tendon sheaths. In the prospective study between June 2013 and March 2016, newly presenting patients with RA, patients with other early arthritides, and healthy control participants all underwent MRI of unilateral MTP joints 1-5. MRI studies were scored by two independent readers for tenosynovitis, synovitis, and bone marrow edema. The association between the presence of these features and RA was examined by using logistic regression. Results Macroscopically, all extensor and flexor tendons crossing MTP joints demonstrated sheaths surrounding tendons. Microscopically, a synovial sheath was present. MRI evaluation was performed in 634 participants: 157 newly presenting patients with RA (109 women; mean age, 59 years ± 11 [standard deviation]), 284 patients with other early arthritides (158 women; mean age, 56 years ± 17), and 193 healthy control participants (136 women; mean age, 50 years ± 16). MRI-detected tenosynovitis was associated with RA, both when compared with patients with other arthritides (odds ratio [OR], 2.5; 95% confidence interval [CI]: 1.7, 3.9; P < .001) and healthy control participants (OR, 46; 95% CI: 14, 151; P < .001). The association was OR of 2.4 (95% CI: 1.5, 3.8; P < .001) for flexor tendons and OR of 3.1 (95% CI: 1.9, 5.2; P < .001) for extensor tendons. The sensitivity of tenosynovitis in RA was 65 of 157 (41%; 95% CI: 35%, 50%). The specificity for RA was 63 of 284 (78%; 95% CI: 72%, 82%) compared with other arthritides, and three of 193 (98%; 95% CI: 96%, 99%) compared with healthy control participants. Conclusion Tendons at metatarsophalangeal joints are surrounded by tenosynovium. MRI-detected tenosynovitis at metatarsophalangeal joints was specific for rheumatoid arthritis when compared with findings in patients with other arthritides and findings in healthy control participants. © RSNA, 2020 Online supplemental material is available for this article.

Conflict of interest statement

Disclosure of Conflics of Interest

The authors YJD, FPJ, MdR, MR and AHMvdHvM disclosed no relevant relationships.

Figures

Figure 1. Macroscopic images and schematic drawings of tendon sheaths in the forefeet.

Drawn red lines represent the level of the MTP-joints. Sheaths are in blue. A. Plantar view of a foot with resin in the flexor tendon sheaths, extending proximal and distal of the MTP joints; B: Schematic: tendon sheaths of the m. flexor hallucis longus tendon (FHL) (1) and the common mm. flexor digitorum longus (FDL) and common flexor digitorum brevis (FDB) tendons (–5). Proximally the four tendons of the FDL run deep of the FDB muscle (6) and extend distally with a common tendon sheath for the FDL and FDB tendons. The tendons of the FDB split to course in a more dorsal position before inserting into the middle phalanx; the tendon of the FDL continue in a straight course and attach to the base of the distal phalanx. The tendon of the FHL (1) proximally runs deep from the musculus abductor hallucis (7) and FDB and inserts at the base of the distal phalanx. C. Dorsal view of a foot with silicone in extensor tendon sheaths, extending from the anterior ankle to distal of the MTP joints; D: Schematic: tendon sheaths of the extensor hallucis longus (EHL) (I) and extensor digitorum longus tendons (EDL) (II-V), forming a common sheath from proximal of the metatarsals to the anterior ankle. The EHL and EDL insert at the dorsal aspect of the distal phalanges. The extensor digitorum brevis (EDB) tendons insert into the EDL II-IV tendons at the MTP-joints and are not portrayed.

Figure 2. Histology of HE-stained, transversely sectioned tendon sheath of the flexor hallucis longus tendon (A, B and C) and of the extensor hallucis longus tendon (D, E and F).

A. Overview of tendon sheath surrounding flexor hallucis longus tendon. B. Overlay with 1. tendon; 2. artery in vinculum; 3. parietal layer of tendon sheath; 4. visceral layer of tendon sheath; 5. cul-de-sac of tendon sheath. C. detail of fig. B. with visible synoviocytes (arrows). D. Overview of tendon sheath surrounding extensor hallucis longus tendon. E. Overlay with 1. tendon; 2. vessels in vinculum; 3. parietal layer of tendon sheath; 4. visceral layer of tendon sheath; 5. cul-de-sac of tendon sheath. F. detail of fig. E. with visible synoviocytes (arrows).

Figure 3. Flow chart of participant selection.

EAC: early arthritis cohort; MRI: magnetic resonance imaging. RA was defined according to clinical diagnosis plus fulfilment of the 2010 classification criteria. The ‘other early arthritides’ included the following diagnoses: unclassified arthritis (n=148), psoriatic arthritis or spondyloarthritis (n=45), inflammatory osteoarthritis (n=23), reactive arthritis (n=7), crystal arthropathy (n=21), remitting seronegative symmetrical synovitis with pitting edema (n=12) and other diagnoses (n=28).

Figure 4. Frequencies of the presence of (A) flexor and (B) extensor tenosynovitis per MTP-joint of patients newly presenting with rheumatoid arthritis, patients presenting with other early arthritides and of healthy controls.

MTP: metatarsophalangeal joints. *P

Figure 5. Contrast-enhanced 1.5T MRI of the forefoot in three different patients in corresponding axial (A, C and E) and coronal (B, D and F) planes showing extensor tenosynovitis at MTP 1 (A, B, C, D) and flexor tenosynovitis at MTP 1, 3, 4, 5 (E, F).

All images are T1-weighted fast spin-echo (FSE) with fat suppression after intravenous contrast administration. In A and B circular enhancement is seen of the extensor hallucis longus tendon, shown from the level of MTP 1 to the base of MT1, consistent with tenosynovitis (arrowheads). Synovitis of MTP 1 is visualized and edema of the skin and subcutis medially (arrow). The axial sequences (A) illustrate that the tenosynovitis is ‘sheath-like’ and continues distally to the MTP-joints (arrowheads). In C andD circular enhancement is present at the extensor hallucis longus tendon without concomitant synovitis of MTP 1 (arrowhead). In E and F circular enhancement is present at the tendons of the flexor hallucis and common flexor digitorum of MTP 1, 4 and 5 (arrowheads). There is coexisting synovitis at MTP 5 (arrow).