Klinische Untersuchung und erweiterte MRT-Diagnostik des Daumensattelgelenks (DSG) bei Patienten mit Rhizarthrose im Vergleich zu symptomfreien Probanden

Abstract

Introduction Nearly every third woman beyond menopause presents signs of osteoarthritis of the carpometacarpal joint of the thumb (CMC I) on conventional x-rays. These signs include primarily joint space narrowing, subcortical sclerosis and the presence of osteophytes. It is also one of the most frequently surgically treated osteoarthritis of the upper extremity. But until now, there has existed neither consent nor a guideline on the basis of which to decide on the optimal surgical treatment in symptomatic osteoarthritis of CMC I. Purpose In this clinical study the CMC I of asymptomatic volunteers were compared with those of patients with osteoarthritis using an advanced magnetic resonance imaging (MRI) in four functional end-range positions (extension, flexion, abduction, adduction). Within these acquisitions the first objective was to assess differences in the frequency and location of ligament lesions of CMC I. The second objective was to analyze and quantify dorsal and radial subluxation of metacarpal I (MC I) using a 3D-approach. The angle of inclination of the proximal articular surface of MC I (MR volar tilt) as well as changes affected by osteoarthritis were also evaluated, and the results were compared between patients and asymptomatic volunteers. Methods The study included 20 carpometacarpal joints of the thumb of 14 asymptomatic volunteers (6x both sides), mean age 42 years (23-57 years) and 28 carpometacarpal joints of the thumb of 22 patients (6x both sides), mean age 53 years (28-73 years) with symptomatic osteoarthritis of CMC I. Each CMC I was examined in four different thumb positions using a custom-made hand orthesis. We used a flexible standard ring coil in a 3-T MRI system (Siemens, Magnetom Trio). Two reconstructed standard imaging planes were necessary for a comprehensive evaluation of the following major ligaments in the four thumb positions: anterior oblique (AOL), dorsal radial (DRL), intermetacarpal (IML) and posterior oblique ligament (POL). Dorsal and radial translation of MC I and the MR volar tilt were assessed in paracoronal and parasagittal planes using multiplanar reconstruction. In addition to MR-imaging a standardized clinical examination was performed in both groups. Results In asymptomatic volunteers, the AOL was ruptured in 5 % and the IML in 15 %. Neither combined ligament lesions nor dorsal ligament lesions were observed. In patients, isolated rupture of AOL was found in 21 %, isolated IML rupture was found in 14 %, combined rupture of AOL and IML was found in 18 %. Dorsal ligament lesions were found in 18 %. In contrast to asymptomatic volunteers, dorsal translation of MC I during flexion of CMC I in patients was not corrected to normal values but remained in pathological subluxation. MR volar tilt measured in sagittal plane was greater in patients than in asymptomatic volunteers. For the radial translation of MC I only minimal differences between the two groups were found. Conclusion Patients with symptomatic osteoarthritis of CMC I present with combined ligament ruptures that most often involve the AOL. In these patients, the dorsal translation of MC I is more pronounced and MR volar tilt angle is increased. In addition to conventional x-rays, MR imaging should be taken into account when ligament reconstruction, osteotomy or prosthetic replacement of CMC I is intended.