Enzymatic recontouring of auricular cartilage in a rabbit model.
OBJECTIVE
To evaluate the effectiveness of contouring auricular cartilage in a rabbit model using biologically active enzymes injected subcutaneously.


METHODS
The first phase determined the most effective volume and concentration required to affect the cartilage. To accomplish this task, we used ex vivo rabbit ears from a slaughterhouse. In the second phase, we injected 1 mL of hyaluronidase (150 U per milliliter of isotonic sodium chloride solution [saline]), elastase (1 mg per milliliter of saline), or saline into the ears of live rabbits. The study took place at the Madigan Army Medical Center (Tacoma, Wash), and included 10 animals. In each rabbit, we injected the test compound in one ear and saline in the other ear (control). We injected hyaluronidase in 5 ears and elastase in 5 ears. After injection, the ears were contoured and splinted for 4 weeks. In the third phase, we changed the injection pathway in 5 animals.


RESULTS
At 4 weeks, 4 (80%) of the 5 ears injected with hyaluronidase showed full response and 1 (20%) had a partial response. Of the 5 ears injected with elastase, 4 (80%) showed a full response while 1 (20%) demonstrated a partial response. There was a response in all 10 of the ears injected with a test compound. Of the 10 control ears, 3 (30%) showed a partial response. At 6 weeks, approximately 6 (30%) of the ears had maintained contour demonstrating a full response. The difference between the test ears and the control ears was statistically significant (P = .006). Compared with the control ears, the results were statistically significant for elastase (P = .004) and hyaluronidase (P = .02). Overall, both agents demonstrated a subjective and objective response compared with control ears.


CONCLUSIONS
This study demonstrates that bioactive enzymes and splinting can be effective in correcting ear deformities in a rabbit model.
Massengill
Phillip L
PL
Otolaryngology Service, Department of Surgery, Madigan Army Medical Center, Tacoma, Wash, USA. phillip.massengill@na.amedd.army.mil
Goco
Paulino E
PE
Norlund
L Layne
LL
Muir-Padilla
Jeanne
J
D000818:Animals; D016009:Chi-Square Distribution; D004425:Ear Cartilage / Q000601:surgery*; D004426:Ear Deformities, Acquired / Q000188:drug therapy*; D004431:Ear, External / Q000601:surgery*; D006821:Hyaluronoglucosaminidase / Q000008:administration & dosage / Q000494:pharmacology*; D007279:Injections, Subcutaneous; D010196:Pancreatic Elastase / Q000008:administration & dosage / Q000494:pharmacology*; D011817:Rabbits; D012965:Sodium Chloride / Q000008:administration & dosage; D018709:Statistics, Nonparametric; D013536:Suture Techniques
D012965:Sodium Chloride; D006821:Hyaluronoglucosaminidase; D010196:Pancreatic Elastase