Computer-Assisted Microvascular Free Flap Reconstruction and Implant Rehabilitation of the Maxilla—Treatment of a Rare Post-orthognathic Complication

Abstract

Orthognathic surgery is generally a safe and predictable procedure. Major postoperative complications are rare and often non-life threatening. An example of a rare complication associated with the LeFort I osteotomy is avascular necrosis of the maxilla (ANM). While cases of ANM have been described in the literature, the majority involves only a portion or segment of the maxillary complex and is commonly treated with conservative measures such as strict oral hygiene, hyperbaric oxygen therapy and local debridement. Occasionally, larger segments of osteonecrosis may require extensive reconstruction such as bone grafting with local soft tissue flaps. Here, we present a patient that underwent a single-stage microvascular free tissue reconstruction with concomitant placement of dental implants and a patient-specific implant (PSI) for post-orthognathic ANM.

Introduction

While orthognathic surgery is generally safe, complications may arise perioperatively, with the non-life threatening complications occurring most frequently. Among the rare complications is avascular necrosis of the maxilla (ANM) following the LeFort osteotomy. Common risk factors associated with ANM include multiple segmental osteotomies, large anterior movements (> 9 mm) or transverse expansion, surgeon inexperience with unusual intraoperative surgical techniques and handling of soft tissues, and additional medical comorbidities [1–3]. Although there have been reports of ANM in the literature, most involve relatively small segments of the maxillary alveolus and are managed with conservative local therapy [2–11].

Here, we present a case of near-complete loss of the maxilla following ANM which resulted from a one-piece LeFort 1 advancement. The patient underwent staged surgical debridement that ultimately resulted in an infrastructure maxillectomy defect (Brown Class 2C). Utilizing the principles of orthognathic surgery including cephalometric prediction, reconstruction was planned using computer-assisted surgery (CAS) and a three-segment free vascularized fibula flap (FVFF), with simultaneous placement of implants for prosthetic rehabilitation. To our knowledge, this is the first case of catastrophic ANM following orthognathic surgery that underwent a one-staged microvascular free tissue reconstruction with the concomitant placement of dental implants and a patient-specific implant (PSI).

Case Report

We present a case of a 51-year-old female who underwent a LeFort 1 osteotomy with a 5 mm advancement 3 weeks prior for maxillary hypoplasia by an experienced maxillofacial surgeon. Her medical history included controlled essential hypertension. She was a non-smoker, social alcohol user, and denied illicit drug use. The patient reportedly had an uneventful surgery and perioperative course and was discharged home the morning following the surgery. Per the surgeon’s routine protocol, the descending palatine arteries were cauterized intraoperatively. At the one-week follow-up appointment, the palate and maxillary gingiva bilaterally were notably pale. Additionally, the patient endorsed bilateral maxillary vestibular and palatal pain, nasal speech, and midface paresthesia. ANM was diagnosed, and the patient was promptly referred for hyperbaric oxygen therapy (HBOT) and started on pentoxifylline and tocopherol (PENTO). The patient was planned for 5–10 consecutive days of HBOT of 2.0–2.4 atmospheres absolute (ATA) with the total number of days dependent on clinical response. After 7 consecutive days of HBOT and minimal improvement, she was referred to our clinic for further management. On examination, we noted pale palatal and maxillary gingival tissue with a posterior oro-nasal fistula, exposed maxillary bone, and mobile teeth (Fig. 1). These findings were consistent with the diagnosis of ANM. Initial workup of the patient included a panorex, computed tomography angiography (CTA) of the neck and face, hematology consultation to rule out hypercoagulable disorders and vasculitides and consultation with the maxillofacial prosthodontist to discuss dental rehabilitation. CTA demonstrated intact and patent ascending pharyngeal and ascending palatine arteries bilaterally, and hematologic workup was negative for any hematologic disorders, including hypercoagulable states or autoimmune vasculitides.

Fig. 1.

Clinical photograph showing the maxilla 3 weeks after LeFort 1 osteotomy with the presence of a posterior oro-nasal fistula (white circle), receding palatal soft tissue front (white dashed line and arrows), exposed necrotic bone of the left maxilla (yellow arrow) (a). Left maxillectomy specimen and teeth (b)

Despite one month of conservative therapy with local wound care, antibiotics, chlorhexidine gluconate irrigation, HBOT, and PENTO, there was progressive soft tissue necrosis, bone exposure and mobility of teeth. In order to assess the viability of the maxilla, the patient was examined under general anesthesia, where the left maxilla was determined to be non-viable and removed, resulting in a Brown Class 2A defect. Meanwhile, the overlying soft tissue of the right maxilla demonstrated some evidence of perfusion, which was confirmed using SPY Elite Fluorescence Imaging (Stryker Corp, Kalamazoo, Mich) (Fig. 2).

Fig. 2.

Intraoperative perfusion assessment using SPY Elite Fluorescence Imaging (Stryker Corp, Kalamazoo, Mich) of the right maxilla demonstrated adequate soft tissue perfusion (dashed yellow line, and yellow arrow) at the time of the left maxillectomy procedure

Over the following 2 months, there continued to be progressive gingival recession (2–3 mm), bone exposure, Grade III mobility of the remaining right maxillary dentition, and mobility of the alveolar segment. Given the guarded prognosis of the remaining dentition of the right maxilla, we decided, in conjunction with the patient, to remove the ailing right maxilla at the time of the definitive reconstruction. Using CAS, a three-segment FVFF with six dental implants and a patient-specific selective laser melted custom plate (KLS Martin KP, Jacksonville, FL) was planned and executed without complications (Fig. 3). Following orthognathic surgery, we deemed that the teeth and skeletal positions were in the ideal functional and aesthetic positions. As such, the position of the fibula was planned to maintain these positions. During the virtual surgical plan, the fibula was placed 15 mm cranial to the occlusal plane to allow adequate prosthetic space for a fixed-hybrid prosthesis. The fibula was also positioned to allow implants to emerge in the central fossa/cingulum of the maxillary dentition. On the day of surgery, patient-specific cutting guides were fabricated and used for the fibula osteotomies. The same cutting guide incorporated holes to facilitate fully guided dental implant placement. Therefore, the osteotomies of the fibula, placement of dental implants, and fixation of the fibula segments to the PSI were completed at the leg while still connected to the vascular pedicle. The neo-maxilla was then transferred to the oral cavity for fixation to the native maxilla and completion of the microvascular anastomosis. Adjunctive procedures including flap debulking and abutment placement were completed four months postoperatively. Finally, a fixed-hybrid dental prosthesis was then fabricated and delivered by the maxillofacial prosthodontist eight months postoperatively (Fig. 4).

Fig. 3.

Virtual surgical plan of the fibula flap, patient-specific selective laser melted plate and the prosthetically guided dental implant positions. The fibula position was adapted from the desired final maxillary position from the orthognathic surgical plan. The fibula was placed 15 mm cranial to the occlusal plane to allow adequate prosthetic space for a fixed-hybrid prosthesis

Fig. 4.

Postoperative photograph of the reconstructed maxilla with the fixed-hybrid prosthesis in place 8 months after implant placement (a), dental occlusion (b) and frontal view (c)

Discussion

Although rare, cases of post-orthognathic avascular necrosis of partial or total maxilla continue to be reported in the literature periodically [1, 8, 9]. Due to sufficient collateral vascular perfusion of the maxilla via the ascending pharyngeal arteries, ascending palatine arteries, and rich network of alveolar branches of the internal maxillary artery, even after the ligation of the descending palatine arteries and/or multiple osteotomies [12, 14–17], the incidence of vascular compromise of the osteotomized segments remains extremely low (< 1%). In 1990, Lanigan et al. sent a questionnaire to 5000 oral and maxillofacial surgeons throughout North America and received 800 responses in which 36 cases were described to have some degree of avascular necrosis of the maxilla after a LeFort 1 osteotomy [4]. In 2004, Kramer et al. evaluated intra- and postoperative complications in 1000 patients who underwent orthognathic surgery and reported 2 cases of bone necrosis limited to the alveolar process [2]. Ten years later, Robl et al. reviewed complications following orthognathic surgery in 1000 of their patients, and found that nearly all of the cases of bone necrosis resolved with local measures, while two cases required gingival grafting and one case resulted in the loss of two teeth [3]. More recently, Lin et al. reported no occurrence of avascular necrosis of any bony segments in 82 of their patients who underwent maxillo-mandibular advancement (MMA) for obstructive sleep apnea (OSA) [18]. Following these large sampled retrospective studies, there have been additional studies that report consistent findings of the low incidence of avascular necrosis of the maxilla following LeFort I osteotomy [3, 10, 18–22].

In addition, several studies have also identified potential risk factors associated with ANM such as variations in anatomy (i.e., vascular anomalies, and cranio-facial deformities), and medical comorbidities (i.e., tobacco smoking, hematological conditions, and autoimmune disease) [8]. Common reported intraoperative risk factors include large anterior movements greater than 9–10 mm, multiple segmental osteotomies, large transverse expansions, poor soft tissue handling or excessive soft tissue dissection resulting in shearing of the vascular supply, and concomitant or previous maxillary or palatal surgery [1–3]. Therefore, in order to decrease the risk and prevent vascular compromise following the LeFort 1 osteotomy, considerations for the formerly mentioned risk factors must be undertaken. A strong knowledge of the vascular supply to the maxilla must be understood in order to avoid shearing of the palatal vascular pedicle when manipulating the osteotomized bone segment(s). If possible, the surgeon should plan to (1) limit the amount of osteotomies used in order to achieve the best outcome, (2) limit the amount of advancement (< 10 mm) and/or transverse expansion, (3) conscientious handling of soft tissue, and (4) take into consideration if there was a history of previous palatal surgeries and design incisions accordingly to preserve the remaining vascular supply. In some cases, the addition of a mandibular setback to decrease the amount of maxillary advancement can help reduce the risk for vascular compromise in a patient without OSA.

Our case was truly unique in that the patient did not have any of the mentioned risk factors. The patient did not have a history or previous maxillary or palatal surgery and underwent an uncomplicated one-piece LeFort 1 osteotomy with a 5 mm advancement, and bilateral descending palatine artery ligation per the primary surgeon’s protocol. Postoperative CTA imaging revealed intact collateral blood supply from the ascending pharyngeal and ascending palatine arteries.

In patients with small regions of necrosis, conservative treatment with strict oral hygiene and HBOT can be rendered and result in satisfactory outcomes [4, 6]. This is due to the robust collateral vascular supply from the ascending pharyngeal arteries, ascending palatine arteries, and mucosal alveolar anastomotic network overlying the maxilla [12]. More extensive osteonecrosis is likely to require surgical debridement with autogenous or allogenic bone grafting [4, 8, 9]. In our case, nonsurgical measures such as strict oral hygiene, PENTO, and HBOT had minimal clinical response. As a result, a more extensive microvascular free flap reconstruction was used to re-establish the maxillary infrastructure and placement of dental implants to aid in dental rehabilitation. Fortunately, with the advantage and accuracy of computer-aided surgery, 3D-printed surgical guides, and patient-specific implants, we were able to plan and execute the aforementioned procedure in a single stage without complications [13]. When planning for a complex total jaw reconstruction in conjunction with osseointegrated implant placement, the use of computer-assisted surgery (CAS) helps improve the accuracy of the osteotomies, predictability of the final reconstruction, and decreases the intraoperative time [23]. Furthermore, only recently was CAS utilized by surgeons for complex jaw reconstruction with immediate implant-supported prosthetic rehabilitation (i.e., Jaw in a Day), [24–27]. Of utmost importance is the proper patient selection for the Jaw in a Day procedure. In a recent review of the Jaw in a Day technique, Patel et al. reported that the technique is ideally limited to patients with minimal soft tissue defects as the presence of a large skin paddle is difficult to manage in relation to the prosthesis and not an ideal peri-implant tissue [28]. As such, this technique is typically reserved for benign pathology as there often less need for extensive soft tissue resection and no need for adjuvant radiotherapy [23, 24]. Workup for CAS will involve the need for high-resolution CT imaging of the maxillofacial region and dental models (obtained digitally or with traditional alginate impressions), and CT angiogram of the bilateral lower extremities. These images are then imported into a surgical planning software where virtual surgery is performed with the aid of a biomedical engineer. Upon the completion of the virtual surgical plan, patient-specific cutting guides, and a patient-specific plate can be designed and fabricated [28, 29].

In the present case, CAS was utilized to facilitate the preplanned osteotomies at the fibula, placement of prosthetically guided dental implants, and fixation of the fibular construct to the native maxilla in the optimal functional and aesthetic position. Since the same fibula cutting guide incorporated predictive holes for the custom plate and dental implants, the entire neo-maxilla fibula construct including the plate could be assembled at the leg while being perfused by the vascular pedicle decreasing the total ischemia time. Unfortunately, due to the large soft tissue defect present, an osteoseptocutaneous flap was required. As a result, the Jaw in a Day technique could not be employed in this instance. Nonetheless, CAS facilitated an accurate and efficient reconstruction in a staged approach with secondary delivery of the implant-supported prosthesis.

Conclusion

Extensive near-total avascular necrosis of the maxilla following Lefort 1 osteotomy remains a rare post-surgical complication. When failed attempts at conservative nonsurgical measures cannot achieve clinical improvement, more complex reconstructive surgery is considered. To date, this represents the first report of reconstruction following ANM utilizing CAS to facilitate FVFF reconstruction with a PSI, and concomitant prosthetically driven implant placement in a single stage.

Funding

No funding source.

Compliance with Ethical Standards

Conflict of interest

The authors declare that they have no competing interests.