Artikel
Stability of the distal radio-ulnar joint provided by the remnant distal radio-ulnar ligaments following ulnar styloid fracture including the fovea: A cadaveric biomechanical study
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Autoren
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Mauro Maniglio
- Inselspital Bern, University Hospital, Bern, Switzerland
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Il Jung Park
- Tibor Rubin VA Medical Center, Long Beach, United States
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Victor Truong
- Tibor Rubin VA Medical Center, Long Beach, United States
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Remy Flueckiger
- Inselspital Bern, University Hospital, Bern, Switzerland
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David Wright
- Tibor Rubin VA Medical Center, Depart of Orthopaedic Surgery, Univ of CA, Irvine, Long Beach, United States
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Michael Kuenzler
- Inselspital Bern, University Hospital, Bern, Switzerland
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Lilianna Bollinger
- Inselspital Bern, University Hospital, Bern, Switzerland
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Matthias Zumstein
- Inselspital Bern, University Hospital, Bern, Switzerland
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Michelle McGarry
- Tibor Rubin VA Medical Center, Congress Medical Foundation, Pasadena, CA, Long Beach, United States
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Thay Lee
- Orthopaedic Biomechanics Laboratory, Congress Medical Foundation, Pasadena, CA, Long Beach, United States
| Veröffentlicht: | 6. Februar 2020 |
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Gliederung
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Objectives/Interrogation: Clinical studies suggest that untreated ulnar styloid fractures (USF) and ulnar styloid non-unions do not affect patient outcomes. This may be due to the contribution of remaining soft tissues providing sufficient residual stability following USF. However, basal USF that include the fovea have a risk of causing distal radio-ulnar joint (DRUJ) instability, because they include deep portion of the distal radio-ulnar ligament (DRUL) insertions. This study investigated the importance of the remaining soft tissue attachment of the DRUL in USF involving the fovea for the stability of the DRUJ.
Methods: Seventeen cadaver forearm specimens (7 male; mean age 64.5) were tested in a custom DRUJ testing system. Soft tissue was carefully removed preserving the interosseous membrane, extensor carpi ulnaris, pronator quadratus, and triangular fibrocartilage complex. The positional change of the DRUJ was measured with a MicroScribe. DP-translation was quantified in neutral, full pronation and 90° supination applying 15 N of translational load. Pronosupination was measured with 1Nm of torque. All specimens were sequentially tested in intact condition, after an ulnar styloid fracture including the fovea, followed by transection of the remaining portions of the DRUL where in eight specimens the remaining dorsal ligaments were transected first and in 9 specimens the palmar ligaments first. Finally stability was tested with both portions of the ligaments transected. Differences were compared using ANOVA and Tukey post hoc tests.
Results and Conclusions: The pronosupination increased significantly compared to the foveal fracture (mean: 205.8°) after transection of both the palmar and the dorsal remaining soft tissue (mean 217.0°; dorsal first: p=0.010; palmar first: p=0.031). The DP-translation significantly increased after transection of both parts of the remaining soft tissue in neutral (dorsal first: p=0.019; palmar first: p=0.018) and supination (dorsal first: p=0.012; palmar first: p<0.001). Transection of one portion of the ligaments did not significantly increase translation; however, the percent increase in dorso-palmar translation was larger for the dorsal tear both when it was transected first or second.
In an USF including the fovea, there are still soft tissues attached to the ulnar head, giving residual stability to the DRUJ. The remaining dorsal portion of the ligaments may have a more important role in the DP-stability.
