The Effect of Specimen Preparation on Post-Excision and Post-Fixation Dimensions, Translation, and Distortion of Canine Cadaver Skin-Muscle-Fascia Specimens.

Abstract

OBJECTIVE: To assess the effect of various tissue apposition techniques on specimens after formalin fixation, and to assess canine cadaveric composite skin-muscle-fascia specimen changes after excision without and with addition of a tumor model. STUDY DESIGN: Canine cadaveric study; unbalanced paired design. ANIMALS: Fresh canine cadavers (n = 30) METHODS: Experiment 1: Paired 7 cm diameter, circular skin-muscle-fascia specimens were harvested bilaterally from three sites (thorax, abdomen, and thigh) on 10 cadavers. For each pair, the skin-to-fascia was sutured with a circumferential continuous pattern in one specimen and left unsutured in the other during excision. Specimen length and width were measured post-excision and post-fixation. Specimen rotation, translation, and distortion was measured post-fixation. Experiment 2: A subcutaneous tumor model was implanted at 2 sites (neck, thorax) on 20 cadavers and specimens were then excised with 2 cm lateral margins and a deep fascial plane. Three suturing techniques of the skin-to-fascia at both sites were performed during excision: unsutured versus circumferential continuous suture (10 pairs) or circumferential versus 4 interrupted quadrant sutures (10 pairs). Lateral margins were compared post-excision and post-fixation. RESULTS: Experiment 1: There was significant reduction in the length and width of the fascia and skin post-excision, but no further reduction after fixation. The circumferential suture decreased rotation and translation of the tissue layers but did not significantly affect specimen shrinkage or distortion compared with the unsutured specimen. Experiment 2: All 4 lateral margins decreased significantly post-excision and post-fixation compared with the planned pre-excision margins. No difference was found between any of the 4 lateral margins for any skin-to-fascia suture technique. CONCLUSION: Canine skin-muscle-fascia specimens significantly decrease in size from gross pre-excision dimensions after removal. Suturing the specimen during surgery before excision will significantly improve alignment of tissue planes without creating distortion of the sample, but may alter the length, width, and lateral margins of the specimen.