Purpose: To delineate the normal magnetic resonance (MR) imaging anatomy of the lesser metatarsophalangeal (MTP) joints in a cadaveric model and compare the MR arthrographic and MR bursographic findings with the standard MR imaging findings.
Materials and methods: T1-weighted spin-echo MR imaging of 48 lesser MTP joints of 12 cadaveric feet was performed. The specimens were subsequently evaluated with MR arthrography, MR bursography, or both examinations. Musculoskeletal radiologists evaluated standard MR images to determine the normal appearances of the joint structures, especially the fibrous capsule, plantar plate, and collateral ligament complex (CLC). Signal intensity, morphology, joint thickness, relationships with adjacent structures, and best plane for analysis were analyzed. The contrast material-enhanced (ie, arthrographic and bursographic) MR imaging findings were compared with the standard MR imaging findings.
Results: The coronal plane was best for simultaneous depiction of the fibrous capsule, plantar plate, and collateral ligament complex and for assessment of the relationship between the CLC and the plantar plate. The sagittal plane was best for analysis of the bone attachments of the plantar plate and the transverse plane for evaluation of the CLC attachment sites in the phalanges. MR arthrography enabled identification of the bare areas and recesses of the joints, better delineation of the plantar plate articular surface, and better evaluation of the integrity of the soft-tissue components of the joints. Compared with the other examinations, MR bursography did not help improve these evaluations.
Conclusion: MR imaging is an excellent examination for delineating the anatomy of the lesser MTP joints. Compared with standard MR imaging, only MR arthrography helps improve visualization of the fibrous capsule, plantar plate, and CLC of the lesser MTP joints.