Artikel
Biomechanical effects of ulnar styloid fracture repair techniques on distal radio-ulnar joint stability
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Veröffentlicht: | 6. Februar 2020 |
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Gliederung
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Objectives/Interrogation: Ulnar styloid fractures (USF) accompany up to 65% of distal radius fractures; however, the cases in which fixation of an USF are indicated is not conclusively defined. Approximatley 10% of USF fractures are addressed surgically but there is no consensus as to the optimum fixation technique to restore stability. Therefore the objective of this study was to compare the pronosupination and the dorso-palmar (DP) translational stability of the distal radioulnar joint (DRUJ) following the repair of USF using four different surgical techniques.
Methods: 9 forearm specimens (1 male; mean age 64.0) were mounted on a custom jig, preserving the interosseous membrane, extensor carpi ulnaris, pronator quadratus, and TFCC. The positional change of the DRUJ was recorded with a MicroScribe. 1Nm torque was applied to measure Pronosupination. DP-translation was measured in neutral, full pronation and 90° supination with 15 N. Six sequential conditions were tested in the same specimen: intact, USF including the fovea and 4 repair techniques (2 K-wire, tension band wiring (TBW), headless compression screw (HCS), and suture anchor).
Results and Conclusions: The pronosupination increased significantly after the foveal fracture from an average of 202.5° for intact to 219.4° (p<0.001) and the DP-Translation in neutral from an average of 8.1 mm for intact to 10.5 mm (p<0.001). The DP-translation in neutral was reduced significantly with all 4 techniques (range: 7.2-8.9 mm; K-wire p=0.006; the other techniques p<0.001). In supination the TBW and suture anchor significantly decreased DP Translation. In neutral rotation the TBW and suture anchor reduced the DP translation even below the intact condition. Only the K-wire fixation (215.1°; p=0.118) and the TBW (to 212.2°; p=0.657) restored the rotation to the intact condition.
All four ulnar styloid fracture repair techniques were effective in restoring DP translation in neutral rotation; however, only K-wire fixation and TBW techniques restored rotational stability. The TBW technique may be biomechanically superior to the other techniques as it was able to restore translational stability in different forearm rotations and also rotational stability.