Martin B. Steed

The Accuracy of Virtual Surgical Planning in Free Fibula Mandibular Reconstruction: Comparison of Planned and Final Results

PURPOSE The concept of virtual surgery uses surgical simulation rather than relying exclusively on intraoperative manual approximation of facial reconstruction. The purpose of this study was to evaluate the degree to which surgical outcomes in free fibula mandibular reconstructions planned with virtual surgery and carried out with prefabricated surgical plate templates and cutting guides correlated to the virtual surgical plan in a series of 11 patients. MATERIALS AND METHODS This retrospective study evaluated 11 consecutive patients (6 males and 5 females) with an average age of 50.73 years (range, 23-72 years) who required mandibular reconstruction for aggressive benign or malignant disease with a free fibula osseomyocutaneous flap at Emory University Hospital (Atlanta, GA) between January 1, 2009 and December 31, 2009. In each case, a high-resolution helical computed tomography (CT) scan of the maxillofacial region and mandible was obtained prior to surgery. The CT data was sent on a CD to a modeling company (Medical Modeling Inc, Golden, CO). The scans were then converted into 3-dimensional models of the maxillofacial skeleton utilizing both automatic and manual segmentation techniques in the SurgiCase CMF software (Materialise NV, Leuven, Belgium). A virtual surgery planning session was held via a Web meeting between the surgeons and the modeling company, at which the resection planes of the mandible, positioning of the plate, and fibula lengths/osteotomy angles were established. The surgery was then carried out using prefabricated cutting guides and manual bending of a reconstruction plate using a prefabricated plate template. A postoperative CT scan of each patient was obtained within the first 7 postoperative days on the same scanner. Three-dimensional computer models of the final reconstruction were obtained for comparison with the preoperative virtual plan. To make the desired comparisons, the 3-dimensional objects representing the postoperative surgical outcome were superimposed onto the preoperative virtual plan using manual alignment techniques. These objects were then compared by 1-to-1 magnification for measurements of fibular bone volume, location of mandibular osteotomies, location of fibular osteotomies, plate contour, plate position on fibula, and plate position on mandible. Comparison was made between the virtual and final plates with regard to contour and position through superimposition overlays of the 3-dimensional models that are registered in the same coordinate system. RESULTS A total of 19 mandibular osteotomies were carried out. The mean distance of the actual mandibular osteotomy when compared to the virtual mandibular osteotomy was 2.00 ± 1.12 mm. The mean volume determined by the software program of the 11 virtual fibulas was 13,669.45 ± 3,874.15 mm(3) (range, 9,568 to 22,860 mm(3)), and the mean volume of the 11 actual postoperative fibulas was 12,361.09 ± 4,161.80 mm(3) (range, 7,142 to 22,294 mm(3)). The mean percentage volumes of the actual postoperative fibula compared to the planned fibula were 90.93 ± 18.03%. A total of 22 fibular segments were involved in the study created by 44 separate fibula osteotomies. The mean distance of the actual fibula osteotomy when compared to the virtual fibula osteotomy was 1.30 ± 0.59 mm. The mean percentage overlap of the actual plate to the virtual plate was 58.73% ± 8.96%. CONCLUSIONS Virtual surgical planning appears to have a positive impact on the reconstruction of major mandibular defects through the provision of accuracy difficult to achieve through manual placement of the graft, even in the hands of experienced surgeons. Although a reasonably high level of accuracy was achieved in the mandibular and fibula osteotomies through use of the surgical cutting guides, the limited ability to correctly contour the plate by hand to replicate the plate template is reflected in our findings.

Microsurgical Repair of the Inferior Alveolar Nerve: Success Rate and Factors That Adversely Affect Outcome

PURPOSE The objectives of this study were to determine the likelihood of regaining functional sensory recovery (FSR) after microsurgical repair of the inferior alveolar nerve (IAN), and which variables significantly affected the outcome of that surgery in a large series of patients. MATERIALS AND METHODS This was a retrospective cohort study that evaluated all patients who had undergone microsurgical repair of the IAN by 1 of the senior surgeons (R.A.M.) from March 1986 through December 2005. The requirements for inclusion of a patient in the study included the availability of a complete chart record and a final follow-up visit at least 12 months after surgery. All other patients were excluded. The predictor variables were categorized as demographic, etiologic, and operative. The final outcome variable was the level of recovery of sensory function as determined by standardized neurosensory testing at the last postoperative visit of each patient and based on guidelines established by the Medical Research Council Scale. Risk factors for surgical failure to achieve useful sensory function were determined from analysis of descriptive statistics, including patient age, patient gender, etiology of nerve injury, chief sensory complaint (numbness, pain, or both), time from injury to surgical intervention (in months), intraoperative findings, and surgical procedure. Logistic regression methods and associated odds ratios were used to quantify the association between the risk factors and improvement. Receiver operator characteristic curve analysis was used to find the threshold of those variables that significantly affected patient outcome. RESULTS In total, 167 patients (41 male and 126 female patients; mean age, 38.7 years [range, 15-75 years]) underwent 186 IAN repairs (19 patients sustained bilateral IAN injuries). The mean time from injury until surgery was 10.7 months (range, 0-72 months). Successful recovery from neurosensory dysfunction (FSR, defined by the Medical Research Council Scale as ranging from useful sensory function to complete sensory recovery) was observed in 152 repaired IANs (81.7%). With increasing duration from date of injury to IAN repair, the likelihood of FSR decreased (odds ratio, 0.898; P < .001). The odds of achieving FSR exhibited a linear decline between the date of nerve injury and its repair, with a significant drop in rate of successful outcome (FSR) occurring beginning at 12 months after injury. There was also a significant negative relationship between increasing patient age and improvement (odds ratio, 0.97; P = .015), with a threshold drop of achieving FSR at 51 years of age. The cause of the injury, the operative findings, and the type of operation performed to repair the nerve had no significant effect on the likelihood of the patient regaining FSR. The presence of pain after nerve injury did not affect the likelihood of achieving FSR after repair in a statistically significant manner (P = .08). In those patients who did not have pain as a major complaint before nerve repair, pain did not develop after microneurosurgery. CONCLUSIONS Microsurgical repair of an IAN injury resulted in successful restoration of an acceptable level of neurosensory function (FSR) in most patients (152 of 186 repairs [81.7%]) in this study. The likelihood of regaining FSR was inversely related to both time between the injury and its repair and increasing patient age, with significant threshold drops at 12 months after nerve injury and at 51 years of age, respectively.

Advances in Bioengineered Conduits for Peripheral Nerve Regeneration

Although resorbable NGCs have been developed for peripheral nerve grafting, there has been little published on their use as a material for trigeminal nerve repair. Advances in engineered guidance channels and modifications to the single-lumen conduit with growth-permissive substrates, ECM proteins, neurotrophic factors, and supportive Schwann or stem cells, and anisotropic placement of these within the NGC may translate from animal models to clinical human use in the future. A great deal of research is still needed to optimize the presently available NGCs, and their use in peripheral trigeminal nerve repair and regeneration remains yet to be explored. Bioengineered NGCs and additives remain promising alternatives to autogenous nerve grafting in the future. They can incorporate all of the developing strategies for peripheral nerve regeneration that develop in concert with the ever-increasing understanding of regenerative mechanisms. The use of nanomaterials also may resolve the numerous problems associated with traditional conduit limitations by better mimicking the properties of natural tissues. Since cells directly interact with nanostructured ECM proteins, the biomimetic features of anisotropic-designed nanomaterials coupled with luminal additive ECMs, neurotrophic factors, and Schwann cells may provide for great progress in peripheral nerve regeneration.

Facial Trauma Coverage Among Level-1 Trauma Centers of the United States

PURPOSE A large portion of patients admitted to trauma centers present with isolated or concomitant facial injuries. Multiple surgical specialties including oral and maxillofacial, plastic, and otolaryngology/head and neck surgeons are trained and involved in the management of oral and maxillofacial trauma. The purpose of this study is to evaluate the current distribution of different specialties that cover facial trauma among the leading trauma centers in the United States. MATERIALS AND METHODS Based on the number of emergency department admissions, the 5 busiest hospitals for each state within the United States were determined from the American Hospital Association, representing a total of 255 hospital emergency rooms. Seventy-six (N = 76) level-1 trauma centers were identified by directly contacting the hospital facility. Information was requested by mail from the chief of surgery and emergency medicine department regarding the percentage of facial trauma coverage by the different surgical specialties. In addition, the professional societies representing the 3 main specialties: American Association of Oral and Maxillofacial Surgeons (AAOMS), American Association of Plastic Surgeons (AAPS), and the American Academy of Otolaryngologists/Head and Neck Surgeons (AAO-HNS) were contacted to determine an estimate of the number of active members within each specialty. RESULTS Information was obtained from 57 (75%) level-1 trauma hospitals. The remaining 19 (25%) hospitals failed to respond to our survey. The distribution of facial trauma coverage by the different specialties was as follows: plastic surgeons, 39.6%; oral and maxillofacial surgeons, 36.6%; otolaryngologists/head and neck surgeons, 23.3%; and other services (general surgery and oculoplastics), 0.5%. According to the respective professional societies contacted, there are approximately 7,003 plastic surgeons, 6,377 oral and maxillofacial surgeons, and 7,720 head and neck surgeons that are practicing members of their respective societies. CONCLUSION Treatment of facial trauma is an essential and demanding aspect of all the surgical specialties that provide this service. All major trauma centers require the support of facial trauma specialists for management of these injuries. When considering the ratio of surgeons per specialty and the percentage of facial trauma coverage provided by each specialty, oral and maxillofacial surgeons and plastic surgeons provide the greatest proportion of facial trauma coverage among the level-1 trauma centers that participated in the survey.

Bullet Embolus to the Pulmonary Artery After Gunshot Wound to the Face: Case Report and Review of Literature

Gunshot wounds to the face can have devastating effects on local and distant tissues. The amount of local damage is directly proportional to the kinetic energy transmitted by the missile. Distant injuries, not in the path of the bullet, can be incurred by a pressure wave created by the temporary cavity, a secondary projectile, aspiration of the missile or bony fragments, and embolization of the bullet, which is a rare phenomenon. Embolization, aspiration, and ingestion of the missile should be suspected when there is an entry wound but no exit wound and no missile is found on x-ray in the expected area after a gunshot wound to the head and neck. Bullet embolism to the heart after gunshot wound of the mandible has been reported in the literature. There are several case reports of bullet embolization to the pulmonary artery after sustaining gunshot wounds to the chest, abdomen, and/or extremities. The purpose of this article is to present a case of bullet embolization to the pulmonary artery after a gunshot wound to the face, fracturing the mandible along its course, to review the literature, and to offer a strategy for managing such injuries.

Peripheral Nerve Response to Injury

Oral and maxillofacial surgeons caring for patients who have sustained a nerve injury to a branch of the peripheral trigeminal nerve must possess a basic understanding of the response of the peripheral nerves to trauma. The series of events that subsequently take place are largely dependent on the injury type and severity. Regeneration of the peripheral nerve is possible in many instances and future manipulation of the regenerative microenvironment will lead to advances in the management of these difficult injuries.

Nerve Injury and Regeneration

Peripheral nerve injuries vary widely in extent and severity. In the peripheral trigeminal nerve, these injuries may result from extraction of teeth, placement of dental implants, benign and malignant tumor removal, maxillofacial trauma, endodontic procedures, orthognathic procedures, and even local anesthetic injections. Each form of insult results in various extent and type of nerve fiber injury with differing abilities for the nerve to regenerate spontaneously.

Perineurioma of the Tongue: A Case Report and Review of the Literature

A perineurioma (PN) is a rare benign peripheral nerve sheath tumor derived from perineurial cells. Based on clinical and pathologic features, PNs can be classified into 2 major subtypes: intraneural PN (IPN) and the more common extraneural PN (EPN). EPNs and IPNs are extremely rare in the oral cavity, and there have been only 38 reported cases (21 EPNs, 17 IPNs). In the present case, a 20-year-old man presented with a painless left dorsal tongue mass. Excisional biopsy examination indicated a diagnosis of EPN based on microscopic examination with immunohistochemical analysis. Twenty-eight months later the patient presented again with concern for a recurrent lesion. Intraoral examination showed a firm nonulcerated left dorsal tongue mass. Re-excision and microscopic examination with immunohistochemical analysis confirmed the diagnosis of an EPN. This report presents an unusual case of EPN that arose in the tongue and potentially recurred, although the possibility of persistence versus true recurrence exists. In addition, the clinicopathologic characteristics of previously reported cases of oral PN are reviewed.

Surgical Ophthalmologic Examination

Maxillofacial trauma involving injury to the eye and periorbital structures is not uncommon. Oral and maxillofacial surgeons are frequently called on to assess and operate in and around the orbit; it is thus critical to be proficient around the eye because surgical interventions and even physical examinations can cause injury and loss of vision. This article reviews the systematic and accurate assessment of the eye and adnexal structures in a manner appropriate for the oral and maxillofacial surgeon, with a focus on proper examination technique and a high sensitivity for potentially critical abnormalities. A practical approach to performing and recording a detailed ophthalmologic examination is presented, including the assessment of vision, pupillary function, intraocular pressure, and ocular motility, as well as the slit lamp and direct fundoscopic examinations.