Kawano Y, Nakamura T, Tada M, Nagura T, Matsumoto M, Nakamura M, Sato K
Department of Orthopaedic Surgery, School of Medicine, Keio University, Tokyo, Japan.
Department of Orthopaedic Surgery, School of Medicine, International University of Health and Welfare, Tokyo, Japan.
Clin Biomech (Bristol). 2019 Jul;67:8-14. doi: 10.1016/j.clinbiomech.2019.04.013. Epub 2019 Apr 24.
Trapeziometacarpal (TMC) arthrodesis provides stability and strength of the thumb, whereas fixation of the TMC joint restricts motion of the thumb, which may consequently impair the activity of daily living. The objective of our study was to investigate how length and area of the thumb-tip trajectory were reduced after the TMC joint fusion.
Six fresh, frozen cadavers were used for this study. Tension was applied to the distal tendons of 4 extrinsic thumb muscles (extensor pollicis longus, flexor pollicis longus, abductor pollicis longus, and extensor pollicis brevis) by servomotor, whereas tension was applied to 4 intrinsic muscles (abductor pollicis brevis, opponens pollicis, flexor pollicis brevis, and adductor pollicis) using static weights. The thumb-tip trajectory was examined using a motion capture system without tension and with 5 different weights to induce intrinsic muscle tension before and after the TMC joint fusion.
When tension was applied to the intrinsic muscles, the length of the thumb-tip trajectory decreased in all conditions compared with that before the TMC joint fusion, whereas the trajectory decreased only when the abductor pollicis longus was pulled. The overall thumb-tip trajectory area was reduced to approximately 30% compared with that before the TMC joint fusion.
Thumb-tip trajectory was restricted by the TMC joint fusion to approximately 30%. However, the reduced area was found tolerable for performing daily activities. Thus, arthrodesis can be the first-line treatment in patients who wish to engage in activities of daily living without difficulties.
大多角骨-第一掌骨（TMC）关节融合术可提供拇指的稳定性和力量，而TMC关节固定会限制拇指活动，进而可能影响日常生活活动。我们研究的目的是调查TMC关节融合术后拇指尖轨迹的长度和面积如何减小。
本研究使用6具新鲜冷冻尸体。通过伺服电机向4块拇指外在肌（拇长伸肌、拇长屈肌、拇长展肌和拇短伸肌）的远端肌腱施加张力，而使用静态重物向4块内在肌（拇短展肌、拇对掌肌、拇短屈肌和拇收肌）施加张力。在TMC关节融合术前和术后，使用运动捕捉系统在无张力和施加5种不同重量以诱导内在肌紧张的情况下检查拇指尖轨迹。
当向内在肌施加张力时，与TMC关节融合术前相比，在所有情况下拇指尖轨迹的长度均减小，而仅在拇长展肌被牵拉时轨迹减小。与TMC关节融合术前相比，拇指尖轨迹的总面积减少至约30%。
TMC关节融合术使拇指尖轨迹受限至约30%。然而，发现减小的面积对于进行日常活动是可耐受的。因此，关节融合术可以作为希望无障碍地进行日常生活活动的患者的一线治疗方法。
