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00001665-201209000-0001100001665_2012_23_1279_chung_osteogenesis_5article< 73_0_11_9 >Journal of Craniofacial Surgery© 2012 Mutaz B. Habal, MDVolume 23(5)September 2012p 1279–1282Utility of the Ultrasonic Scalpel in Mandibular Distraction Osteogenesis[Original Articles]Chung, Cyndi Uy MS*†; Yu, Jason W. DMD, MD‡; Bastidas, Nicholas MD*†; Bartlett, Scott P. MD*†; Taylor, Jesse Adam MD*†From the *Division of Plastic Surgery, Children’s Hospital of Philadelphia;†University of Pennsylvania Perelman School of Medicine; and ‡Department of Oral and Maxillofacial Surgery, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania.Received December 29, 2011.Accepted for publication February 21, 2012.Address correspondence and reprint requests to Jesse A. Taylor, MD, 3400 Spruce St, 10 Penn Tower, Philadelphia, PA 19104; E-mail: taylorj5@email.chop.eduThe authors report no conflicts of interest.AbstractAbstract: The purpose of this study was to describe our technique of bilateral mandibular distraction for micrognathia and to highlight the ultrasonic scalpel as an alternative to conventional saws in performing osteotomies for mandibular distraction osteogenesis. To do so, we retrospectively reviewed all patients who underwent mandibular distraction with an ultrasonic scalpel for tongue-based upper airway obstruction due to micrognathia between 2010 and 2011.Study outcome measures include operative blood loss, length of surgery, postoperative complications, and avoidance of a tracheostomy. Excel (Microsoft) was used to calculate averages, P values (2-tailed Student t test), and SDs for operative data, sleep studies, and cephalometric analysis.Nine patients—7 females and 2 males—were distracted for a mean distance of 17 ± 6 mm. Mean blood loss was 15 ± 7 mL, and the average length of surgery was 111 ± 27 minutes. One patient returned to the operating room for debridement/washout of a wound infection, but distraction was continued without sequelae. There were no other postoperative complications. Resolution of airway obstruction was evidenced by clinical examination and avoidance of a tracheostomy in all cases.Based on these data, we feel that mandibular distraction with univector, internal distractors, and ultrasonic osteotomies at the mandibular angle is safe and efficacious at relieving tongue-based upper airway obstruction and avoiding a tracheostomy.Mandibular distraction osteogenesis (MDO) is increasingly used as an alternative to tracheostomy and tongue-lip adhesion in those cases of tongue-based upper airway obstruction (TBUAO) that are refractory to conservative measures.1–3 While it is generally felt to be efficacious, there is significant variability in practice, including variable device selection, surgical approach, distraction rates, latency phase, consolidation phase, and complication rates.4,5 The purpose of this study is to describe our technique of bilateral MDO for TBUAO and to highlight the ultrasonic scalpel as an alternative instrument to perform osteotomies in mandibular distraction osteogenesis.What Is This Box?A QR Code is a matrix barcode readable by QR scanners, mobile phones with cameras, and smartphones. The QR Code links to the online version of the article.The ultrasonic scalpel uses a vibrating blade to disrupt tertiary hydrogen bonds and consequently denature proteins.6 Because it vibrates within a specific range of frequencies, the ultrasonic scalpel selectively cuts teeth and bone yet spares soft tissues, which oscillate at the same speed and amplitude as the blade.7 Theoretically, performing osteotomies with an ultrasonic scalpel would promote the preservation of periosteal blood supply and minimize damage to neighboring soft tissue. Consequently, osteogenesis would likely be improved, and complications minimized. This is a retrospective review of our experience with the ultrasonic scalpel in mandibular distraction at the Children’s Hospital of Philadelphia.MATERIALS AND METHODSData CollectionData were collected in concordance with the institutional review board of the Children’s Hospital of Philadelphia. We reviewed the medical records of all patients who underwent mandibular distraction using the piezoelectric scalpel between January 2010 and July 2011. Demographics, preoperative and postoperative cephalometrics, and sleep studies were analyzed. Figure 1 depicts a typical patient in this cohort.FIGURE 1. A, A 3-month-old with cat-eye syndrome who failed conservative measures for relieving tongue-based upper airway obstruction. The parents chose tongue-lip adhesion (TLA) over MDO to avoid a tracheostomy. However, after TLA, the patient required continued oxygen support and nasogastric feeding supplementation. Sleep studies showed severe sleep apnea and hypercapnia, as evidenced by an AHI of 37 and an ETCO2 maximum of 74 during wakefulness and sleep. In addition, the patient was hypoxic during sleep, with an SpO2 minimum of 56% during REM and non-REM sleep. Supplemental conservative measures—continuous positive airway pressure and nasopharyngeal airway—failed to correct the obstruction, and the family was offered MDO or a tracheostomy. They chose to undergo MDO. This is an anteroposterior photograph of the patient before undergoing bilateral MDO with an ultrasonic scalpel. B, Post–tongue-lip adhesion, pre-MDO. Lateral view.Accounting for the nonstandardization of the head position, the mandible of each cephalogram was traced on acetate paper and adjusted to near-centric relation. With these radiographs, we were able to determine the length of distraction of the mandible by comparing the distance between the distractor arms before and after activation. Using these values for the length of distraction, we constructed a preoperative mandible on acetate paper, placing it in almost the same position as the postoperative position. Finally, with these 2 mandibular positions, we were able to determine a preoperative and postoperative SNB to be compared with the fixed SNA.Surgical TechniqueThrough a modified Risdon approach, the inferior border of the angle of the mandible is approached via blunt dissection. A limited subperiosteal dissection is performed to allow placement of the distractor footplates on the proximal body of the mandible to establish a horizontal vector parallel to the occlusal plane (Figs. 2A, 2B). The piezoelectric scalpel (Synthes, Paoli, PA) is then used to create the superior and inferior thirds of the anterior and posterior corticotomies of our vertical body osteotomy (Fig. 2C). The distractor is then fixated with self-drilling, self-tapping screws on either side of the corticotomies, bringing the distractor arm through the skin posterior to the lobule of the ear via blunt dissection. After fixation, the midportions of the corticotomies are completed, and the device is activated to “greenstick” the medullary cavity of the bone. Great care is taken to avoid injury to the inferior alveolar nerve and tooth roots. Once completeness of the osteotomy is confirmed, the device is returned to its initial position, and the soft tissues are closed in layers.FIGURE 2. A, Using a Risdon approach, the mandible is marked for corticotomy. B, The piezoelectric scalpel is used for the superior and inferior thirds of the anterior and posterior corticotomies. C, The distractor is fixated with self-drilling screws to the site of the corticotomy, with the distractor arm piercing the skin posterior to the lobule of the ear. Once the distractor is rigidly fixated, corticotomies are completed, and the distractor is activated to ensure completeness of the osteotomy.Distraction ProtocolThe 2 primary surgeons used different distraction protocols. Both surgeons use a 48-hour latency. One surgeon (J.A.T.) then distracts 1 mm BID for 5 days followed by 1 mm/d until the end point is reached, whereas the second surgeon (S.P.B.) distracts at 1 mm/d throughout. Patients were followed up weekly with x-rays to confirm the device functionality and distance of distraction. The end point of distraction is determined by clinical examination, a slight overcorrection with 1 to 2 mm of underjet, and formal microlaryngoscopy/bronchoscopy by a pediatric otorhinolaryngology surgeon. After the end point is attained, a consolidation phase of either 2 months or twice the duration of the activation phase is undertaken, and the device is subsequently removed (Figs. 3–6).FIGURE 3. A, X-ray after distractor placement, during latency period. anteroposterior view. B, X-ray after distractor placement, during latency period. Lateral view.FIGURE 4. A, Anteroposterior photograph of the patient at the end of the activation phase of MDO. He underwent a 2-month consolidation period thereafter. Note the mild class III skeletal relationship. B, Lateral view at completion of the activation phase.FIGURE 5. A, X-ray from consolidation phase. Anteroposterior view. B, X-ray from consolidation phase. Lateral view.FIGURE 6. A, Anteroposterior photo of the same patient 6 months after removal of the distractor. B, After removal of distractor. Lateral view. C, Postdistractor removal anteroposterior x-ray. D, Postdistractor removal lateral x-ray.RESULTSNine patients were identified for this study—7 females and 2 males. All patients fit the clinical triad of Pierre Robin sequence: glossoptosis, micrognathia, and cleft palate. In addition, 2 patients had CHARGE syndrome, and 1 had cat-eye syndrome (Table 1). The indications for mandibular distraction osteogenesis included patients with airway obstruction secondary to micrognathia and glossoptosis who failed conservative management. These patients also had tongue-based upper airway obstruction and obstructive sleep apnea based on clinical examination; consensus by neonatology, otorhinolaryngology, and pediatric plastic surgery; and 16-lead polysomnograms read by a consistent group of pediatric pulmonologists specializing in sleep medicine.TABLE 1 Demographic Data and Preoperative Sleep Studies of Patients Undergoing MDOPreoperative 16-lead polysomnograms were obtained in 6 (66%) of 9 patients—2 patients were intubated, and one was not studied. The average Apnea-Hypopnea Index (AHI) was 23.1 ± 13.1 (normal <5). For total sleep, the average minimum SpO2 was 70.8% ± 16.5%. Of patients’ total sleep time, 23.0% ± 37.4% was spent in SpO2 of less than 90%. The sleep study results are further elaborated in Table 1.The perioperative record and postoperative complications are summarized in Table 2. Patients lost an average of 15 ± 7 mL of blood in surgery, and the average length of surgery was 111 ± 27 minutes. One patient returned to the operating room for washout and debridement of a wound infection, and distraction was continued without sequelae. There were no other postoperative complications. There was no evidence of marginal mandibular nerve palsy, tooth-bud injury, or sensory deficit.TABLE 2 Intraoperative Blood Loss, Length of Operation, Postoperative Complications, and Cephalometric ChangesAs shown in Table 2, the cephalometric analysis illustrated the changes in mandibular projection after distraction osteogenesis. The mean preoperative SNB value was 64 ± 5 degrees compared with a mean postoperative SNB value of 82 ± 8 degrees (reference range of SNB is 76–82 degrees), P < 0.05. The mean preoperative ANB was 10 ± 4 degrees, whereas the mean postoperative ANB was −6 ± 11 degrees (normal ANB values range from 1–5 degrees). Patients were distracted an average length of 17 ± 6 mm, which generally resulted in a mild skeletal class III relationship with 1 to 2 mm of underjet.DISCUSSIONIn his investigation into the optimal conditions for distraction osteogenesis, Ilizarov8 observed that bone regeneration was initiated by “fibroblast-like cells,” which congregated around sinusoidal capillaries. His work confirmed what was already widely suspected: the better preserved the endosteal and periosteal blood supply, the more robust the osteogenesis.8 This finding is frequently implicated in the debate between the use of internal and external mandibular distractors. Given that external distractors often require less periosteal stripping than internal distractors, it is believed that external distraction consequently provides better conditions for osteogenesis by maintaining a better blood supply,9 a fact highlighted by Gosain and colleagues10 in a recent publication on the importance of preservation of periosteum for improved blood supply during distraction.The importance of preserving the vascularity during the osteotomy and placement of the distractors cannot be understated. However, traditional instruments used in osteotomies such as oscillating saws and burrs are, by design, imprecise and emit thermal energy, which can damage surrounding soft tissue and bone.11 To improve conditions for osteogenesis following mandibular distraction, it would be beneficial to find a device that is precise, cuts bone while leaving soft tissues unharmed, and damages the cellular milieu required for osteogenesis the least.A common tool in orthopedics and neurosurgery, the ultrasonic scalpel surpasses drills and saws in avoiding soft tissue and thermal damage. Drills and saws provide minimal feedback on different tissue densities, and wide dissection must often be performed to minimize tissue damage during the osteotomy. Because the blade of the ultrasonic scalpel vibrates between 28 and 36 kHz—the frequency at which soft tissues such as nerves and blood vessels oscillate—the ultrasonic scalpel does not cut soft tissue. This feature is especially important in MDO, during which the surgeon must take care to avoid injury to the inferior alveolar nerve and tooth buds. The irrigation system for the piezoelectric system also removes bone debris, improves visualization, and controls temperature.7In practice, the ultrasonic scalpel has been shown to improve outcomes in numerous ways. Nordera11 observed that patients who received craniofacial osteotomies with ultrasound technology reported less discomfort and swelling postoperatively than did patients receiving traditional osteotomies. In cadaver studies of Le Fort osteotomies, Taylor et al12,13 found that the ultrasonic scalpel cut bone easily and rarely penetrated the periosteal sleeve. With this precision comes additional security in avoiding damage to surrounding vasculature, such that the authors also reported that the ultrasonic scalpel severed only the endosteal blood supply and minimally disrupted periosteal blood supply, preserving the anastomotic networks of the face.13 This finding is not surprising, as traditional saws damage wider areas of bone and consequently may damage neighboring tissue and delay osteogenesis and healing.8,12–14Other studies have affirmed the advantage of piezoelectric technology in minimizing blood loss. Sinha and Gallagher6 found that although steel and ultrasonic scalpels are comparable in rates of reossification and resolution of inflammation, the ultrasonic scalpel is superior in preserving hemostasis and maintaining control between tissue planes. Our estimated blood loss during surgery with the piezoelectric scalpel compares favorably to other reports in the literature. For example, Denny and Amm15 reported a blood loss of 30 mL using a conventional saw in MDO in neonates. Studying their use in conventional bimaxillary osteotomies, Landes et al16 found that piezoelectric osteotomy reduced average blood loss as compared with conventional saws by more than 200 mL. It would be useful to perform a prospective study in which we compare blood loss, swelling, and bone regeneration in this patient population.This small, retrospective case series is meant to highlight a new tool that is useful in performing osteotomies and is not meant to end the debates on internal versus external distraction, vertical versus horizontal vector, and various activation protocols. Although some surgeons prefer external distractors because of their flexibility and ability to advance in multiple vectors,9 for bilateral mandibular distraction to relieve tongue-based airway obstruction, we prefer internal distractors because of their greater rigidity and univector (horizontal) advancement. In our experience, increased rigidity allows for better vector control and osteogenesis. We also prefer a horizontal vector, as we believe it correlates with a greater airway clearance per millimeter advanced.There are several limitations to this retrospective chart review of our surgical technique. It is a small, heterogeneous cohort with limited follow-up. There is no established universal protocol for MDO in neonates. The protocol in this article was designed based on our experience: slower rates of distraction may lead to premature consolidation, whereas faster rates may lead to decreased quality ofthe regenerated bone. Although we are mainly reporting our surgical technique, we also present short-term follow-up. A longer period of follow-up is needed to adequately assess the technique’s ability to prevent recurrence of sleep apnea, dental complications, and mental nerve function. The short follow-up period also does not allow for commentary on mandibular growth—a key “fourth” dimension when operating at this early time point. And although we have seen drastic improvement in O2 saturation, we have not done postoperative polysomnograms on all patients in this cohort. Thus, our clinical assessment of “efficacy” may be overstated. Ideally, we would perform sleep studies postoperatively to further document functional improvement. Lastly, using neonatal cephalograms in the measurement of SNB and ANB values can be difficult and imprecise. Because of the difficulty of obtaining lateral cephalograms on young patients, the quality of the lateral cephalograms varied not only among patients but also among each patient’s serial cephalograms. In addition, the patients’ SNA and SNB values changed continually as their skulls and mandibles rapidly expanded. To eliminate as much variability as possible, an attempt was made to provide a complete data set over the shortest amount of time. Unfortunately, computed tomographic scans are difficult to obtain in patients this young, as they would likely require sedation—a risky proposition in patients with Pierre Robin sequence.CONCLUSIONSPiezoelectric technology is a useful adjunct in mandibular distraction osteogenesis, providing several advantages over traditional instruments. The ultrasonic scalpel’s ability to cut bone while minimizing trauma to soft tissues such as nerves and tooth buds is especially beneficial in the neonatal mandible.REFERENCES1. Kohan E, Hazany S, Roostaeian J, et al.. Economic advantages to a distraction decision tree model for management of neonatal upper airway obstruction. Plast Reconstr Surg 2010; 126: 1652–1664 [Context Link]2. Denny A, Talisman R, Hanson P, et al.. Mandibular distraction osteogenesis in very young patients to correct airway obstruction. Plast Reconstr Surg 2001; 108: 302–311 [Context Link]3. Genecov D, Barceló C, Steinberg D, et al.. Clinical experience with the application of distraction osteogenesis for airway obstruction. J Craniofac Surg 2009; 20: 1817–1821 [Context Link]4. Shetye P, Warren S, Brown D, et al.. Documentation of the incidents associated with mandibular distraction: introduction of a new stratification system. Plast Reconstr Surg 2009; 123: 627–634 [Context Link]5. Mofid M, Manson P, Robertson B, et al.. Craniofacial distraction osteogenesis: a review of 3278 cases. Plast Reconstr Surg 2001; 108: 1103–1114 [Context Link]6. Sinha UK, Gallagher LA. 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J Oral Maxillofac Surg 2008; 66: 657–674 [Context Link] Mandibular distraction osteogenesis; ultrasonic scalpel; tongue-based upper airway|00001665-201209000-00011#xpointer(id(R6-11))|11065213||ovftdb|00005537-200302000-00007SL00005537200311322811065213P51[CrossRef]|00001665-201209000-00011#xpointer(id(R6-11))|11065404||ovftdb|00005537-200302000-00007SL00005537200311322811065404P51[Full Text]|00001665-201209000-00011#xpointer(id(R6-11))|11065405||ovftdb|00005537-200302000-00007SL00005537200311322811065405P51[Medline Link]|00001665-201209000-00011#xpointer(id(R9-11))|11065213||ovftdb|00020840-200412000-00009SL0002084020041251311065213P54[CrossRef]|00001665-201209000-00011#xpointer(id(R9-11))|11065404||ovftdb|00020840-200412000-00009SL0002084020041251311065404P54[Full Text]|00001665-201209000-00011#xpointer(id(R9-11))|11065405||ovftdb|00020840-200412000-00009SL0002084020041251311065405P54[Medline Link]|00001665-201209000-00011#xpointer(id(R11-11))|11065213||ovftdb|00006534-200712000-00031SL000065342007120198911065213P56[CrossRef]|00001665-201209000-00011#xpointer(id(R11-11))|11065404||ovftdb|00006534-200712000-00031SL000065342007120198911065404P56[Full Text]|00001665-201209000-00011#xpointer(id(R11-11))|11065405||ovftdb|00006534-200712000-00031SL000065342007120198911065405P56[Medline Link]|00001665-201209000-00011#xpointer(id(R14-11))|11065213||ovftdb|00001665-201003000-00044SL0000166520102147911065213P59[CrossRef]|00001665-201209000-00011#xpointer(id(R14-11))|11065404||ovftdb|00001665-201003000-00044SL0000166520102147911065404P59[Full Text]|00001665-201209000-00011#xpointer(id(R14-11))|11065405||ovftdb|00001665-201003000-00044SL0000166520102147911065405P59[Medline Link]|00001665-201209000-00011#xpointer(id(R15-11))|11065213||ovftdb|00005186-200507000-00025SL0000518620051479711065213P60[CrossRef]|00001665-201209000-00011#xpointer(id(R15-11))|11065404||ovftdb|00005186-200507000-00025SL0000518620051479711065404P60[Full Text]|00001665-201209000-00011#xpointer(id(R15-11))|11065405||ovftdb|00005186-200507000-00025SL0000518620051479711065405P60[Medline Link]16027704Utility of the Ultrasonic Scalpel in Mandibular Distraction OsteogenesisChung, Cyndi Uy MS; Yu, Jason W. DMD, MD; Bastidas, Nicholas MD; Bartlett, Scott P. MD; Taylor, Jesse Adam MDOriginal Articles523