High-resolution ultrasound anatomy of extrinsic carpal ligaments

Carpal ligaments can be classified as intrinsic and extrinsic. Extrinsic ligaments are often involved in carpal instability. The purpose of this article is to describe the sonographic appearance of extrinsic carpal ligaments on high-resolution ultrasound (HRUS) using magnetic resonance arthrography (MR arthrography) as a reference standard.

We studied both wrists in 18 healthy volunteers (ten men, eight women, age range 18-58 years, mean age 34 years) with a Philips iU22 US scanner equipped with a high-resolution linear-array broadband transducer (5-17 MHz). The scans were performed along the long axis of the extrinsic dorsal and ventral ligaments to assess their course, thickness and structure. Ten subjects were also studied with MR arthrography of the wrist.

In all patients, the ligament components could be appreciated as thin fibrillar hyperechoic structures. The course of seven extrinsic carpal ligaments and their relationships with surrounding articular structures could be studied. The radioscapholunate and the ulnar collateral ligaments were not visible on US. MR arthrography depicted all ligaments except for the ulnar collateral, which was never visualised.

The results obtained are consistent with those reported in the literature. HRUS provides good anatomical detail of the extrinsic carpal ligaments, but the role of US in planning the treatment of carpal instability disorders is yet to be demonstrated.