gms | German Medical Science

Objectives/Interrogation: Most Galeazzi fractures can be treated adequately with ORIF of the radius alone, but some will remain unstable at the DRUJ and require repair of the TFCC. The purpose of this study was to define and measure DRUJ dislocation and instability associated with the sequential sectioning of the different bands in the interosseous membrane (IOM) and TFCC in a simulation of a Galeazzi fracture.

Methods: Twelve fresh-frozen cadaver forearms were dissected and the differents parts of the IOM were measured. Their were 6 men and 6 women with a mean age 74 years-old. We examine the anatomy and function of the forearm IOM and define the importance of anatomic divisions within IOM. Each forearm was them mounted into a wrist and forearm biomechanical device (Mecmesin AFG/AFTI Multitest-d ®, Virginia, USA). We simulated a radius fracture in all the specimens. A force of 25 N, 50 N and 75 N was applied. The load data (N) were correlated with the displacement data (cm). We sequential sectioning: 1) Central Band (CB); 2) CB plus Distal Oblique Bundle (DOB); and 3) CB plus DOB plus TFCC. The degree of displacement (cm) in DRUJ were measured in the three groups with the different loads. We evaluated differences in variables using Student's t-test and ANOVA for groups. We considered 2-tailed p values less than 0.05 to be statistically significant.

Results and Conclusions: In the specimens the average radial length was 23.38 cm and the average ulnar length was 25.5 cm. The average length of the radial origin was 13 cm and the ulnar origin was 5.7 cm. The CB has an average width of 2.5 cm. The CB of the IOM contributes 70% to the mechanical stiffness of the forearm, while the TFCC contributes 20% and the DOB contributes 10%. In-group 1 applying progressive loads (25/50/75 N) the average DRUJ displacement (cm) was 4.3, 5.9, and 7.9 cm respectively. In-group 2 was 5.2, 5.7, and 6.9 cm respectively. In-group 3 was 6.2, 8.1, and 9.9 cm respectively. Our study showed a correlation between the increase in applied load to the same injury and the degree of displacement (P=0.001). In-group 3 the degree of DRUJ displacement was statistically significant (p= 0.04).

CB is the crucial region within the IOM in restraining proximal migration. The TFCC also acts to resist proximal radial migration. Migration of the radius under loads implies disruption of both the CB and the TFCC. The DOB does not seem to have a relevant role in the displacement and in the transverse instability in forearm.