Fiber type morphometry and capillary geometry in free, vascularized muscle transfers

Abstract

In order to establish the relationship among intraoperative ischemia time, the recovery of contractile function, muscle fiber morphometry, and capillary geometry following free muscle transfer, 15 male dogs underwent unilateral, orthotopic free transfer of the left gracilis muscle with microneurovascular anastomosis. Intraoperative ischemia time varied from 0 to 4 hours. After a recovery period averaging 14 months, isometric contractile function was measured in the transfers and the contralateral, control muscles. Muscle fiber type composition, fiber size, and capillary geometry were quantified from histochemical sections. Transferred and control muscles had similar type I fiber percentages, type I fiber sizes, and capillary densities. Type II fiber sizes were reduced in transfers relative to controls. There was no significant effect of intraoperative ischemia on any morphometric variable. Although contractile function was generally reduced after free, vascularized transfer, there was only a weak correlation between the recovery of tetanic tension and type I fiber percentage (r = 0.53, P less than 0.05). It is concluded that free, vascularized muscle transfer results in minimal disturbance of muscle fiber type composition, fiber size, or capillary supply and that the diminished contractile function observed in this setting is still largely unexplained.

The Effect of Reinnervation on Force Production and Power Output in Skeletal Muscle

“…The CSA of all EDL muscles and all individual muscle fibers was determined using computerized planimetry (Bioquant, R and M Biometrics, Inc., Nashville, TN) in accordance with previously established methods [29,32]. From the muscle fiber-type distribution and fiber CSA data, the relative CSA fraction for Types SO, FOG, and FG fibers was computed [34].…”

Termino-lateral neurorrhaphy: The functional axonal anatomy

“…The muscles were stained with hematoxylin and eosin (H & E) and myosin ATPase (mATPase) at five different pH levels (10.4, 9.4, 4.5, 4.3, and 3.8). [17][18][19][20] Muscle fibers were classified as either slow oxidative (SO), fast oxidative glycolytic (FOG), or fast glycolytic (FG), based upon differential staining to mATPase. 21,22 Ten-micron thick cross sections of the epon-embedded tibial nerve graft were obtained using a microtome (DuPont, Wilmington, DE).…”

Neurovascular Transfer Does Not Cause Skeletal Muscle Fiber Degeneration

“…Because both capillary geometry and blood flow are largely unchanged after neurovascular muscle transfer, it is unlikely that changes in muscle perfusion account for the mechanical deficits observed in muscle transfers. 41,42 In contrast, available data suggest that, under many circumstances, denervation/reinnervation and tenotomy and repair can result in deficits in skeletal muscle contractile function. 16,18,26,[43][44][45] These factors must remain the prime independent variables in future studies of mechanical function in neurovascular muscle transfer.…”