Dynamic in vivo evaluation of radiocarpal contact after a 4-corner arthrodesis.

ABSTRACT

PURPOSE: To understand the mechanisms that preserve joint integrity after 4-corner arthrodesis (FCA). METHODS: We investigated the long-term changes of the radiolunate articulation after an FCA for different motions of the wrist in a cross-sectional study that included wrists of 10 healthy participants and both operated and nonoperated wrists of 8 individuals who had undergone FCA on 1 side. The average postoperative follow-up period of the FCA group was 5.7 years. The radiolunate articulation was assessed from dynamic 3-dimensional distance maps during wrist motion. Contact surface area, centroid position of the articular area, and distance between radiolunate articular surfaces were measured and compared between healthy subjects and operated and nonoperated wrists of FCA patients. RESULTS: The total radiolunate articulation area was larger in patients with FCA. The average radiolunate joint space thickness was preserved in the operated FCA wrists. The centroid of the articulation area was shifted radially and dorsally in FCA wrists. CONCLUSIONS: Changes of the motion pattern of the lunate during radioulnar deviation and flexion-extension of the wrist after FCA can explain the shift of the centroid radially and dorsally. TYPE OF STUDY/LEVEL OF EVIDENCE Diagnostic IV.