Stress distribution pattern in the distal radioulnar joint before and after ulnar shortening osteotomy in patients with ulnar impaction syndrome

Kazutoshi Hontani,Norimasa Iwasaki,Yuichiro Matsui,Daisuke Kawamura,Atsushi Urita,Hiroki Hamano,Daisuke Momma

doi:10.1038/s41598-021-97398-x

Kazutoshi Hontani, Norimasa Iwasaki + Show 5 more

Open Access

https://doi.org/10.1038/s41598-021-97398-x

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Abstract

Ulnar shortening osteotomy (USO) for ulnar impaction syndrome potentially leads to degenerative changes of the distal radioulnar joint (DRUJ). This study was performed to evaluate the effect of the sigmoid notch morphology on the stress distribution pattern of the DRUJ using computed tomography (CT) osteoabsorptiometry (CT-OAM). We reviewed the pre- and postoperative transverse CT images of 15 wrists that had undergone USO. The examined wrists were classified into two groups based on the sigmoid notch morphology: the linear-type notch (type L) and the curved-type notch (type C). We calculated and statistically compared the percentage of the high-density area (%HDA) in each divided region of the sigmoid notch. In type L, %HDA was significantly larger in the distal-dorsal region of the sigmoid notch before USO. Postoperatively, in type L, no specific regions showed a significantly different %HDA. In type C, %HDA was significantly larger in the distal-volar region of the sigmoid notch before USO. Postoperatively, %HDA of type C was significantly larger in the proximal-volar region. Our results suggest that in patients with ulnar impaction syndrome, morphological evaluation of the sigmoid notch can serve as a predictor of osteoarthritis in the DRUJ with or without USO.

Highlights

Ulnar shortening osteotomy (USO) for ulnar impaction syndrome potentially leads to degenerative changes of the distal radioulnar joint (DRUJ)
Osteoarthritis of the DRUJ has been reported as a complication after USO16,19
The bone morphology of the DRUJ and alterations of the stress distribution pattern within it are two factors that result in o steoarthritis[5,20,21]

Summary

Introduction

Ulnar shortening osteotomy (USO) for ulnar impaction syndrome potentially leads to degenerative changes of the distal radioulnar joint (DRUJ). In type L, %HDA was significantly larger in the distal-dorsal region of the sigmoid notch before USO. In type C, %HDA was significantly larger in the distal-volar region of the sigmoid notch before USO. Our results suggest that in patients with ulnar impaction syndrome, morphological evaluation of the sigmoid notch can serve as a predictor of osteoarthritis in the DRUJ with or without USO. Radiographic findings in patients with ulnar impaction syndrome frequently show positive ulnar v ariance[1], but can include neutral or negative ulnar variance with a thickened TFCC2. Ulnar shortening osteotomy (USO) is widely performed as a surgical treatment for ulnar impaction syndrome, several researchers have reported the occurrence of radiologic osteoarthritic changes in the distal radioulnar joint (DRUJ) after U SO3,4. Because of these dynamic and morphologic features of the sigmoid notch, it is difficult to determine the changes in the stress distribution pattern at the sigmoid notch after USO in the living body using the conventional biomechanical method

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