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Dynamic Functioning of Latissimus Dorsi Muscle NeoSphincters Compared to Native Anal Sphincters in the Rat
Melanie G. Urbanchek^*1, Shiuhyang Kuo², Zhifa Wang², Jana D. Moon¹, Eve L. Bingham², Elizabeth A. Mays¹, Hyungjin (Myra) Kim³, Paul S. Cederna¹, Stephen E. Feinberg^2,1
1Surgery, University of Michigan, Ann Arbor, MI; ²Dental School, University of Michigan, Ann Arbor, MI; ³Public Health, University of Michigan, Ann Arbor, MI

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.
METHODS:
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.
RESULTS:
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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