Jan 24 2005
Results from a Mayo Clinic laboratory study in animals suggest that using distraction osteogenesis, a procedure that uses the mechanical force of an appliance to lengthen soft tissue and bone, may be a feasible and effective method to repair cleft palate in the future.
Oral facial clefts are birth defects in which the tissues of the mouth or lip don't form properly during fetal development. In the United States, clefts occur in 1 in 700 to 1,000 births, making it the fourth most common major birth defect.
"Right now, nobody tries to close cleft palate with distraction osteogenesis," says Eric Moore, M.D., Mayo Clinic otorhinolaryngologist and one of the study's investigators. "It's used in other areas of the body and other craniofacial problems, but not in cleft palate. Before taking it to the clinic to use in people, we wanted to try it in an animal model. This study tells us that it is possible to close cleft palate with distraction osteogenesis."
The Mayo Clinic researchers conducted this study in animals in order to find a method of repairing a child's cleft palate that would be even better than the current standard surgery. The distraction osteogenesis method is designed to gradually lengthen the bone of the palate through tension. An appliance made of a central body piece, four plates and screws is surgically inserted with the patient under anesthesia. After a rest period of 10 days, a key in the appliance is turned slightly each day for four weeks to slowly lengthen the bone and soft tissue. Finally, the device is surgically removed.
"This method of repairing a cleft palate is potentially superior to standard surgery because it brings in bone and soft tissue to cover the opening," says Bob Tibesar, M.D., chief resident in Mayo Clinic Department of Otorhinolaryngology and a study investigator. "This has positive implications for the shape of the palate and for speech later."
Currently, standard treatment for cleft palate repair involves surgery in which the mucosal flaps of the roof of the mouth are sewn together over the cleft. The actual missing bone is not repaired. Some of the potential downsides of this repair method, according to Dr. Moore, can include leaving exposed areas of hard palate bone, producing scars that sometimes interfere with the child's later midfacial growth. This growth impairment can lead not only to a poor cosmetic appearance, but also can lead to poor contact between lower and upper teeth when the child's mouth is closed. The lack of actual bony repair of the cleft, in addition to the tension placed on the mucosal flaps on the roof of the mouth during traditional cleft palate repair surgery, also increases risk of the wound splitting open or the creation of an abnormal passage between the mouth and nose. The current repair method also may shorten and scar the soft palate, which can impair speech.
The study of this method of cleft palate repair was conducted on 10 adult hounds, due to similarities to the human mouth. Two hounds served as study controls and had a surgically created cleft palate, but no subsequent repair. In the other eight hounds, the distraction osteogenesis device was used to close the cleft palate. In seven of the eight hounds that were treated, the researchers observed some degree of bony closure of the cleft; in five of them the cleft was closed completely with no side effects.
The Mayo Clinic researchers are currently working on perfecting the technique through study of the hounds with incomplete closure. The researchers also felt that the distraction osteogenesis device used in this study was too bulky, so they are now testing another more agile apparatus, says Dr. Moore.
"We continue to work on improving this procedure in the laboratory," says Dr. Tibesar. "We are not ready to perform this yet on human patients, but we are hopeful that day will come soon."
Uldis Bite, M.D., Mayo Clinic plastic surgeon, co-director of Mayo's Cleft Palate/Craniofacial Clinic and co-investigator in this research project, echoes this sentiment. "While this study shows great promise, it cannot currently be applied to the treatment of children with clefts of the lip and palate. We are still honing this technique in the laboratory. Meanwhile, it is important to know that in most children, the standard techniques of cleft lip and palate repair and careful multidisciplinary follow-up through our Cleft Palate/Craniofacial Clinic give excellent results."