Artikel
Trapezio-trapezoid (TT) hypermobility may increase range of thumb movement after trapezio-metacarpal (TMC) arthrodesis
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Autoren
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Shohei Omokawa
- Nara Meidcal University, Department of Hand Surgery, Kashihara, Japan
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Junya Hojyo
- Nara Meidcal University, Department of Orthopedic Surgery, Kashihara, Japan
| Veröffentlicht: | 6. Februar 2020 |
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Gliederung
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Objectives/Interrogation: We conducted kinematic analysis of the thumb using fresh cadaveric extremities to investigate the range of thumb circumduction after TMC arthrodesis with/without associated peri-trapezial resection procedure.
Methods: Eight upper arms were separated at the distal forearm and MCP joint. The hand and forearm other than the thumb ray were fixed to the laboratory table. We attached 3-D electromagnetic tracking sensors to the base and head of the 1st metacarpus. A 50-gf load was applied at a point 20 cm distal from the TMC joint to generate the thumb circumduction. We then measured the magnitude of angular and rotational displacement of the 1st metacarpus during the movement. Data were collected in normal thumb (stage0), thumb with simulated TMC fusion (stage1), that with subsequent resection of the TT joint (resection width in 2mm, stage2), and with further resection between the 2nd metacarpal base and trapezium (stage3). The 1-2 intermetacarpal and scapho-trapezial ligaments were left intact during the experiment.
Results and Conclusions: The average range of angular movement of the normal thumb (stage0) demonstrated 58° and 66° respectively, in radial and palmer abduction-adduction directions. After TMC arthrodesis (stage1), these angular movements showed significant reduction to 17° and 13°, respectively. Rotational movement of the normal thumb (42°and 34°) reduced significantly after the arthrodesis (8° and 5°). Following sequential T-T resection (stage2), the angular and rotational displacement increased significantly (37° and 25°, 22° and 13°, respectively) compared to the thumb with TMC fusion (stage1). These movements further increased in stage3 (49° and 39°, 34°and 25°, respectively), and demonstrated 71% and 78% of normal thumb motion.
TMC arthrodesis decreased the range of thumb circumduction; 24% (angulation) and 17% (rotation) of normal thumb motion. Hypermobility of TT and trapezio-2nd metacarpal joint contributed to remarkable increase of thumb movement without significant instability.
