Laryngeal reconstruction following vertical partial laryngectomy (VPL) with arytenoidectomy was studied in 30 dogs. Variations of a superiorly based thyroid cartilage flap (TCF) were used for reconstruction. In addition, sternohyoid muscle reconstruction and endolaryngeal muscle coverage were studied. Larynges were recovered after a 6-month period in 28 surviving dogs and were analyzed by endoscopic photographs and axial whole-organ sections. Endoscopic assessment (n = 18) demonstrated good results for arytenoid replacement (100%), pseudocord position (94%), pseudocord development (94%), and airway patency (100%). Arytenoid replacement was judged as completely (78%) or partially (22%) replaced. This was accomplished by a pseudocord extending to the cricoid in the horizontal plane. Pseudocord position was judged as normal (83%) or paramedian (11%), with the remainder lateralized (6%). Pseudocord development was judged as complete (72%) or partial (22%), with the remainder poor (6%). Reviewing both endoscopic photographs and gross sections (n = 28), airways were all normal without laryngeal or tracheal stenosis. Histologic assessment (n = 24) also demonstrated good results for arytenoid replacement (79%), pseudocord position (87%), and TCF survival in the glottic plane (79%). Arytenoid replacement was judged as complete (62%) or partial (17%), with the remainder poor (21%). Pseudocord position was judged as normal (50%) or paramedian (37%), with the remainder lateralized (13%). TCF survival was judged as total (63%) or partial (16%). Although not present in the glottic plane in the remaining cases (21%), a portion of the TCF was always present in the supraglottic region. The TCF was largely replaced by bone in the region of the pseudocord, and was covered by nonkeratinizing stratified squamous epithelium and a thick fibrous layer. Breakdown over the TCF was infrequent, with a small focus of granulation tissue over cartilage present in 1 (4%) of 24 cases. Clinically insignificant granulation tissue was present in a total of 6 (25%) cases. In the other 5 cases, this was over muscle or over permanent sutures. Focal cartilage necrosis was present in 2 (8%) of 24 cases, and was localized, self limiting, and deep to the endolaryngeal surface. When the TCF failed to survive histologically, poorer results for arytenoid replacement and pseudocord position generally resulted. However, this apparent difference was not statistically significant due to small sample sizes and variability in results. Other factors that may have kept this difference from becoming larger were thought to be contraction of the normal cord towards the operated side with foreshortening of the glottis, and medial rotation and ossification of the posterior thyroid ala remnant. Sternohyoid muscle flap reconstruction and endolaryngeal muscle coverage were also investigated. Bipedicled sternohyoid flaps exhibited no loss as compared to the contralateral bipedicled sternohyoid muscle used as a control. Unipedicled flaps lost 23% in cross-sectional area in the axial plane as compared to the bipedicled flaps used for reconstruction (P = .0423) and the contralateral bipedicled sternohyoid control (P = .0341). Three types of endolaryngeal muscle coverage were used: perichondrium, mucosa, and no coverage. The no-coverage group showed 16% less underlying sternohyoid muscle area than the perichondrium or mucosa groups, but this difference was not statistically significant. Nonkeratinizing stratified squamous epithelium was present over the muscle, but there were no differences in cell-layer thickness between perichondrium (5.8), mucosa (5.9), and no coverage (6.0). Cell-layer thickness over the opposite normal control mucosa (7.6) was significantly greater than either mucosa over muscle (5.9, P<.0001) or mucosa over the bony pseudocord (5.6, P = .0005).
