Saving Face with Innovative Surgical Techniques

With a large number of mandibular reconstruction patients presenting as children, there is great incentive to develop approaches and techniques that decrease morbidity. According to Dr. Kaban, approximately eighty-five percent of pediatric mandibular reconstruction patients require skeletal expansion, traditionally achieved with bone grafts or soft-tissue flaps harvested from an autologous donor site—typically the patient’s hip, skull, or ribs.

In addition to the obvious risks—donor sites require a second operation to harvest bone—the fact that they are children poses other drawbacks. There may be inadequate bone to harvest, leading to multiple donor sites, and bone resorption is unpredictable, which may result in an undesired loss of volume. “We are actively seeking novel ways to create new bone to avoid donor-site harvesting,” explains Dr. Kaban.

Established by Dr. Kaban in 1996, the Skeletal Biology Research Center (SBRC) focuses on developmental skeletal biology for the purpose of advancing leading edge reconstructive techniques and adapting them to clinical practice. Currently under the direction of Dr. Troulis, the team has taken great strides toward decreasing morbidity for patients. “Our research is eclectic but with a single goal: to decrease morbidity for patient,” emphasizes Dr. Troulis.

Distraction Osteogenesis

One of the most promising new techniques is distraction osteogenesis (DO), the gradual lengthening of bone using a specialized appliance (a “distractor”) to place tension forces across an osteotomy. Candidates for this procedure are children with micrognathia, midface hyperplasia (cleft lip/palate, Cruozon or Apert syndrome), and those with acquired conditions resulting from trauma, tumor resection, or radiation therapy.

The benefits of DO can be numerous. In addition to avoiding donor-site morbidity, the procedure can be performed using minimally invasive techniques, sometimes endoscopically. In micrognathic patients, studies show that DO permits the jaw to be moved greater distances than with conventional surgery and that the newly created bone appears to be more stable.

The journey from bench to bedside is multidisciplinary and multifaceted. The SBRC is focused on studying the biology of bone-wound healing and muscle response, minimally invasive access, distractor device design, and 3-D treatment planning.

One of the greatest innovations to emerge from this work is a semi-buried, miniature distraction device that is capable of accurate 3-D movements along a curvilinear path. The goal is to develop a totally buried device driven by a micromotor that moves automatically. In partnership with industry, the SBRC has several grants to pursue this development, leading toward a complete approach including a 3-D treatment planning system that incorporates software developed in the Harvard Surgical Planning Laboratory.

“In the future, skeletal expansion in the craniomaxillofacial region will be achieved with far less morbidity, greater patient comfort, and more predictable, higher quality outcomes,” notes Dr. Kaban.

Bibliography

Steinbacher DM, Kaban LB, Troulis MJ. Mandibular advancement by distraction osteogenesis for tracheostomy-dependant children with severe micrognathia. J Oral Maxillofac Surg 63(8):1072-1079, 2005.

Yeshwant K, Seldin EB, Gateno J, Everett P, White CL, Kikinis R, Kaban LB, Troulis MJ. Analysis of skeletal movements in mandibular distraction osteogenesis. J Oral Maxillofac Surg 63:335-340, 2005.

Thurmueller P, Troulis MJ, Rosenberg A, Chuang SK, Kaban LB. Microscopic changes in the condyle and disc in response to distraction osteogenesis of the minipig mandible. Int J Oral Maxillofac Surg (in press)

Yeshwant K, Seldin EB, Kikinis R, Kaban LB. A computer-assisted approach to planning multidimensional distraction osteogenesis. Atlas Oral Maxillofac Surg Clin N Am 2005;13:1-12.