Dynamic Functioning of Latissimus Dorsi Muscle Flap NeoSphincters Compared to Native Anal Sphincters in the Rat
Elizabeth A. Mays, MSE, Eve L. Bingham, MS, Jana D. Moon, BS, Zhifa Wang, DDS, Shiuhyang Kuo, DDS, Hyungjin (Myra) Kim, PhD, Randal S. Smith, HS, Paul S. Cederna, MD, Steven E. Feinberg, DDS, PhD, Melanie G. Urbanchek, PhD.
Universitiiy of Michigan, Ann Arbor, MI, USA.
PURPOSE: Patients with fecal incontinence from oncologic resection, trauma, extensive sphincter defect, or infection require surgery to maintain health and hygiene. Pedicled flaps are a reconstruction mainstay. This study compares dynamic functions of anal sphincters constructed using neurovascular pedicled latissimus dorsi muscle (LDM) free flaps with those of native anal sphincters.
Neo sphincters were constructed off one shoulder of athymic rats. Native sphincters (NativeS, n=16) were controls. Experimental surgeries all began with elevation of the LDM and eventual formation into a neosphincter with a lumen. Groups were: a) LDM only (NeoS, n= 7), acellular dermal matrix (ADM) lining the neosphincter lumen (NeoS-ADM, n=4), and ADM prelaminated during tissue culture with human oral muco-epithelial cells (NeoS-Mucosa, n=10). Recovery was 14 days when manometric pressures were measured.
All neosphincters were well vascularized and healthy. Resting pressures after accommodation for manometer balloon inflation were all similar: 110, 100, 127, and 130 mmHg for NativeS, NeoS , NeoS-ADM, and NeoS-Mucosa groups respectively. Maximal evoked pressures also were very similar (Fig 1). The muco-epithelial layer increased in thickness while in vivo (Fig 2).
CONCLUSIONS: Viable neosphincters with a human muco-epithelial lining provided pressures similar to the native anal sphincter in the rat.
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