Ultrasonography of the Hand in Rheumatology by Peter Vince Balint & Peter Mandl

Author:Peter Vince Balint & Peter Mandl
Language: eng
Format: epub
Publisher: Springer International Publishing, Cham

Fig. 4.8Coronal CT image with grooves on the radial aspect of the capitate (arrow) and the ulnar aspect of the distal scaphoid (arrow head) representing characteristic pseudoerosions, the latter with slightly overhanging edges. Undulating shallow grooves on the radial aspect of the scaphoid (small arrows) represent insertions of innominate mucosal folds

A groove may be observed at a non-apophyseal direct tendon or ligament attachment, at an apophysis with overhanging edges of the bone or at the indirect attachments of a tendon or ligament with tangential transition into t he periosteum. The latter are incompletely formed apophyseal structures and present rather as jutties than as real grooves. Many such grooves exist in the hand, mainly at ligament insertions. A great variety of such grooves may be observed, particularly around the capitate and at its neighboring bones, not only at the strong “V”-ligament insertions but also at small intrinsic ligaments insertions [69]. On its radial surface, the capitate may have a prominent groove of varying size which forms an asymmetric capitate waist. At the carpometacarpal, the MCP and the finger joints, grooves occur at the bases of the metacarpal bones or at the phalangeal bases in the form of small round or oval subcapsular notches. The nonspherical form of metacarpal and metatarsal heads can be explained by t he collateral ligament complexes with smoothly outlined shallow metacarpal grooves containing these structures [44]. At the metacarpals, these grooves are bordered by little tubercles for the proximal attachment of the collateral ligaments [44]. A focal decalcification on projection radiographs or CT images with hazy borders should not be assessed as a pseudoerosion but rather as a “pre-erosion” with increased focal osteoclast activity.

The roof of a bony sulcus is formed by a ligament, fascia or other fibrous tissue, thus forming an osteofibrous ch annel for a tendon within a synovial sheath. Pseudoerosions due to such a tangentially displayed channel may be typically observed at the waist of the scaphoid under the flexor pollicis longus and the flexor carpi radialis tendons.

A surface roughness is an area of bone, not covered by periosteum or cartilage. It is located adjacent to often innominate ligaments or synovial folds, to tendons or to nutritional vessels. A differentiation from shallow and in most cases chronic forms of erosions or from severe cartilage degeneration may be difficult. Some of them may be specified as crests or ridges that corresp ond to attachment sites for a redundant joint capsule. Nutritional channels of bone vessels may open to the surface of a bone with their orifice appearing hyp erintense on T2-weighted MR images [65, 70].

Conclusion

Precise and detailed anatomical concepts and terms are necessary to meet today’s requirement of diagnosing arthritis in its early, clinically suspected and preclinical stages. Especially with MRI, a continuous overlap is observed between normal osseous concavities and erosions as well as between synovitis due to overuse, degeneration or clinically suspected arthritis. A combined biomechanical and immunologic concept in understanding the origins and pathways of inflammation and degeneration might help improve the diagnostic accuracy and precision.

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