The carpometacarpal joint of the thumb: MR appearance in asymptomatic volunteers

Abstract

PURPOSE: To prospectively characterize the MR appearance of the carpometacarpal (CMC) joint of the thumb in asymptomatic volunteers. MATERIALS AND METHODS: Thirty-four asymptomatic volunteers (17 women, 17 men, mean age, 33.9 ± 9.2 years) underwent MR imaging of the thumb after approval by the local ethical committee. Two musculoskeletal radiologists independently classified visibility and signal intensity (SI) characteristics of the anterior oblique (AOL/beak ligament), the posterior oblique (POL), the intermetacarpal (IML), and the dorsoradial ligaments (DRL) on a threepoint Likert scale. The thickness of all ligaments, cartilage integrity, and presence of joint fluid were assessed. The alignment of the first metacarpal base with the trapezium was quantified on sagittal and coronal planes. RESULTS: The ligaments of the CMC joint were constantly visible in all volunteers for the POL and IML, and in all but one for the AOL and DRL. On intermediate-weighted fat-saturated images the POL (65 %/74 % reader 1/reader 2) and DRL (58 %/64 %) were commonly of increased SI, while the IML had a striated appearance in 91 %/76 % of subjects. The AOL showed a variable SI (36 %/42 % low, 27 %/27 % increased, 36 %/30 % striated). The IML was the thickest ligament with a mean of 2.9 mm/3.1 mm and the DRL the thinnest (1.2 mm/1.4 mm). There was a mean dorsal subluxation of 1.8 mm/2.0 mm and radial subluxation of 2.8 mm/3.4 mm of the metacarpal base. The AOL was significantly thicker in men (1.7 mm) than in women (1.2 mm; p = 0.02). Radial subluxation was significantly larger in men (3.4 mm) than in women (2.2 mm; p = 0.02). No subluxation in palmar or ulnar direction was seen. CONCLUSIONS: Radial and dorsal subluxation of the CMC joint can be a normal finding in a resting position at MR imaging. The CMC ligaments showed a considerable variability of signal intensity with a typically striated IML; thickness of the AOL is typically less than 2.2 mm, of the POL typically less than 2.9 mm. Abstract Purpose To prospectively characterize the MR appearance of the carpometacarpal (CMC) joint of the thumb in asymptomatic volunteers. Materials and methods Thirty-four asymptomatic volunteers (17 women, 17 men, mean age, 33.9 ± 9.2 years) underwent MR imaging of the thumb after approval by the local ethical committee. Two musculoskeletal radiologists independently classified visibility and signal intensity (SI) characteristics of the anterior oblique (AOL/beak ligament), the posterior oblique (POL), the intermetacarpal (IML), and the dorsoradial ligaments (DRL) on a three-point Likert scale. The thickness of all ligaments, cartilage integrity, and presence of joint fluid were assessed. The alignment of the first metacarpal base with the trapezium was quantified on sagittal and coronal planes. Results The ligaments of the CMC joint were constantly visible in all volunteers for the POL and IML, and in all but one for the AOL and DRL. On intermediate-weighted fat-saturated images the POL (65 %/74 % reader 1/reader 2) and DRL (58 %/64 ...

Ultrasound of Normal and Injured Ligaments and Retinacula of the Hand

“…44,46 The AOL was shown to be thicker in men (1.7 mm) than women (1.2 mm) on MRI. 47 Dynamic stress imaging of the AOL is performed by applying dorsally directed pressure to the volar base of the first metacarpal. 11…”

“…It is more often combined with a fracture of the first metacarpal base. 47 With Bennett fracture dislocation injuries, the deep AOL maintains its articular surface attachment to the proximal ulnar metacarpal fragment, whereas the remainder of the metacarpal is pulled in a radial direction by the abductor pollicis longus, frequently resulting in wide diastasis of the articular surface. Less frequently, injury is due to a direct blow into the first web space of the thumb, such as may be produced by a motorcycle handlebar at impact.…”

“…Incongruity of the articular surfaces seen with US may support clinical suspicion of joint instability. Because the TMC joint is not congruent at rest, 47 it may be difficult to recognize pathologic subluxation, and comparison with the contralateral asymptomatic side is often useful. Dorsally directed stress on the base of the first metacarpal may demonstrate increased joint incongruity and widening of volar TMC joint space secondary to metacarpal translation.…”

High-Resolution MR Imaging and US Anatomy of the Thumb

“…The AOL is much thinner than the dorsal ligament complex but still functionally important. The term beak ligament is frequently used to refer to either the total AOL complex or the deep portion specifically (7). With Bennett fracture-dislocation injuries, the deep AOL maintains its articular surface attachment to the proximal ulnar metacarpal fragment, whereas the remainder of the metacarpal is pulled in a radial direction by the APL, frequently resulting in wide diastasis of the articular surface (4).…”

“…The dorsal radial ligament and posterior oblique ligament together form the dorsal ligament complex, which acts as the primary restraint to dorsal radial metacarpal dislocation (1,4). The ligaments of the dorsal ligament complex may demonstrate internal intermediate signal intensity on images obtained in asymptomatic patients (7).…”