Do Dang-Huy, Heineman Nathan, Crook Jennifer L, Ahn Junho, Sammer Douglas M, Koehler Daniel M
Department of Orthopaedic Surgery, University of Texas Southwestern Medical Center, Dallas, TX.
Department of Plastic Surgery, University of Texas Southwestern Medical Center, Dallas, TX; University of Tennessee Health Science Center, Memphis, TN.
J Hand Surg Am. 2025 Jun;50(6):756.e1-756.e7. doi: 10.1016/j.jhsa.2024.03.016. Epub 2024 May 3.
Multiple procedures have been described for wrist and finger flexion contractures and spasticity. Fractional lengthening of forearm flexor tendons involves making parallel transverse tenotomies at the musculotendinous junction to elongate the muscle. Currently, there is limited literature to define the biomechanical consequences of this lengthening technique.
Forty-eight flexor tendons were harvested from eight paired upper limbs including flexor carpi radialis, flexor carpi ulnaris, flexor pollicis longus, and flexor digitorum superficialis tendons. Each tendon that was lengthened was paired with the contralateral tendon as a control. A pair of transverse tenotomies were completed for the fractional lengthening. The first tenotomy was performed at the musculotendinous junction where the tendon narrowed to 75% of its maximal width. The second tenotomy was made 1 cm distal to the first. Tendon length was measured before and after fractional lengthening at a constant resting tension of 1 N. The maximum load at failure of each tendon and the mechanism of failure were each measured and compared with the contralateral side.
After fractional lengthening, the mean increase in resting tendon length was 4 mm. When loaded to failure, the mean maximum load of fractionally lengthened tendons was 42% of the mean maximum load of intact tendons. All lengthened tendons failed at the distal tenotomy site.
Fractional lengthening resulted in an increase of 3-6 mm (mean: 4 mm) in tendon length at resting tension. There was a significant loss in tensile strength and load to failure following fractional lengthening compared with an intact musculotendinous unit.
The reduction in tensile strength following fractional lengthening results in loads at failure that are, in some cases, lower than the estimated forces required to perform basic tasks. Caution during the healing and rehabilitation period is warranted.
针对手腕和手指屈曲挛缩及痉挛，已有多种手术方法被描述。前臂屈肌腱的分次延长术是在肌腱肌肉结合处进行平行横向腱切断术以延长肌肉。目前，关于这种延长技术的生物力学后果的文献有限。
从八对上肢中获取48条屈肌腱，包括桡侧腕屈肌、尺侧腕屈肌、拇长屈肌和指浅屈肌腱。每条被延长的肌腱都与对侧肌腱配对作为对照。完成一对横向腱切断术以进行分次延长。第一次腱切断术在肌腱肌肉结合处进行，此处肌腱变窄至其最大宽度的75%。第二次腱切断术在第一次腱切断术远端1厘米处进行。在1 N的恒定静息张力下测量分次延长前后的肌腱长度。测量每条肌腱的最大破坏载荷及破坏机制，并与对侧进行比较。
分次延长后，静息肌腱长度平均增加4毫米。加载至破坏时，分次延长肌腱的平均最大载荷为完整肌腱平均最大载荷的42%。所有延长的肌腱均在远端腱切断术部位发生断裂。
分次延长导致静息张力下肌腱长度增加3 - 6毫米（平均：4毫米）。与完整的肌腱肌肉单元相比，分次延长后肌腱的抗张强度和破坏载荷显著降低。
分次延长后抗张强度的降低导致破坏时的载荷在某些情况下低于执行基本任务所需的估计力。在愈合和康复期间需谨慎。
