Bone contouring and fixation in functional, primary microvascular mandibular reconstruction

Complication rates and clinical outcomes of osseous free flaps: a retrospective comparison of CAD/CAM versus conventional fixation in 128 patients

Studies evaluating plate-related complications in patient-specific versus conventional fixation systems in free flap surgery are lacking. This was a retrospective study of 128 osseous free flaps with a minimum follow-up of 12 months. Wound healing disorders, plate exposure, fixation failure, and subtotal osseous union were recorded and evaluated statistically by univariate and regression analysis. Complication rates were as follows: wound healing disorders 33.6% (computer-aided design and computer-aided manufacturing (CAD/CAM) vs. conventional: 35.1% vs. 33.0%); plate exposure 21.9% (29.7% vs. 18.7%); fixation failure 7.0% (8.1% vs. 6.6%); subtotal osseous union 36.7% (45.9% vs. 33.0%). Radiotherapy (P<0.001) and more than two segments (P=0.026) were independent variables for the overall complication rate and were negatively correlated with the dental implantation rate. The time between diagnosis and ablative surgery was increased by 11.0days in the CAD/CAM group (34.2±16.2days vs. 23.2±12.0 days; P=0.002). Rates of dental rehabilitation were not significantly different (35.1% vs. 44.0%, P=0.358). On average, 3.2±1.7 dental implants were placed into flap segments. Plate-related complications were increased with radiotherapy and multisegment flaps. There was a non-significant trend towards increased complications with patient-specific plates in comparison to conventional reconstruction plates.

Navigation Guidance During Free Flap Mandibular Reconstruction: A Cadaveric Trial

Importance

Segmental mandibulectomy for tumors that distort the buccal surface of the mandible present a reconstructive challenge.

Objective

To determine whether mandible alignment after navigation-guided mandible reconstruction is better than alignment after non-template-assisted freehand reconstruction and as good as template-assisted reconstruction in a cadaveric trial.

Design, Setting, and Participants

A cadaveric trial using 10 specimens was conducted at a tertiary academic center. Fiducials were created on the ramus to compare alignment with each intervention. Segmental mandibulectomy was performed on each cadaver. Each cadaver underwent navigation-guided reconstruction, template-assisted reconstruction using a manually shaped plate, and non-template-assisted freehand reconstruction with plate contouring performed after mandibulectomy. The study was conducted from October 1, 2015, to January 1, 2016; data analysis was performed from February 1, 2016, to March 1, 2016.

Interventions

Segmental mandibulectomy, navigation-guided reconstruction, template-assisted reconstruction using a manually shaped plate, and non-template-assisted freehand reconstruction.

Main Outcomes and Measures

Ramus fiducial coordinates were recorded at baseline and after each intervention. Mandible dimensions were measured using cephalometric landmarks. Postintervention and baseline differences in ramus and mandible position were calculated.

Results

Ramus alignment was not significantly different between navigation-guided and template-assisted reconstruction, differing by 0.54 mm (98.3% CI, -0.38 to 1.47 mm). Non-template-assisted freehand reconstruction was associated with a 3.14-mm difference in alignment compared with template-assisted reconstruction (98.3% CI, 1.09 to 5.19 mm). Navigation-guided alignment resulted in a 3.69-mm improvement in alignment compared with non-template-assisted freehand reconstruction (98.3% CI, 1.79 to 5.58 mm). There was some improvement in the gonion-gonion and lingula mandibulae-lingula mandibulae (Lm-Lm) alignment for navigation-assisted compared with non-template-assisted freehand reconstruction by 1.97 mm (98.3% CI, -0.65 to 4.58 mm) and 1.39 mm (98.3% CI, -0.17 to 2.95 mm), respectively. There was marginal evidence of better Lm-Lm alignment for navigation-guided than template-assisted reconstruction (0.44 mm; 98.3% CI, -0.06 to 0.95 mm).

Conclusions and Relevance

Mandible alignment following navigation-guided reconstruction is similar to template-assisted reconstruction. Navigation-guided alignment is likely better than non-template-assisted freehand reconstruction, and navigation guidance offers a reliable technique for real-time adjustment when reconstructing complex surgical defects, such as tumors effacing the buccal cortex of the mandible.

Prosthesis Loading After Temporomandibular Joint Replacement Surgery: A Musculoskeletal Modeling Study

One of the most widely reported complications associated with temporomandibular joint (TMJ) prosthetic total joint replacement (TJR) surgery is condylar component screw loosening and instability. The objective of this study was to develop a musculoskeletal model of the human jaw to assess the influence of prosthetic condylar component orientation and screw placement on condylar component loading during mastication. A three-dimensional model of the jaw comprising the maxilla, mandible, masticatory muscles, articular cartilage, and articular disks was developed. Simulations of mastication and a maximum force bite were performed for the natural TMJ and the TMJ after prosthetic TJR surgery, including cases for mastication where the condylar component was rotated anteriorly by 0 deg, 5 deg, 10 deg, and 15 deg. Three clinically significant screw configurations were investigated: a complete, posterior, and minimal-posterior screw (MPS) configuration. Increases in condylar anterior rotation led to an increase in prosthetic condylar component contact stresses and substantial increases in condylar component screw stresses. The use of more screws in condylar fixation reduced screw stress magnitudes and maximum condylar component stresses. Screws placed superiorly experienced higher stresses than those of all other condylar fixation screws. The results of the present study have important implication for the way in which prosthetic components are placed during TMJ prosthetic TJR surgery.

Stabilization of mobile mandibular segments in mandibular reconstruction: use of spanning reconstruction plate

The fibular free flap is the gold standard for mandibular reconstruction. Accurate 3-dimensional contouring and precise alignment of the fibula is critical for reestablishing native occlusion and facial symmetry. Following segmental mandibulectomy, the remaining mandibular fragments become freely mobile. Various stabilization methods including external fixation, intermaxillary fixation, and preplating with reconstruction plate have been used. We describe a modification to the preplating technique. After wide resection of buccal squamous cell carcinoma, our patient had an 11-cm mandibular defect from the angle of the left mandible to the right midparasymphyseal region. A single 2.0-mm Unilock® (Synthes, Singapore) plate was used to span the defect. This was placed on the vestibular aspect of the superior border of the mandibular remnants before resection. Segmental mandibulectomy was then performed with the plate removed. The spanning plate was then reattached to provide rigid fixation. The fibular bone was contoured with a single osteotomy and reattached. The conventional technique involves molding of the plate at the inferior border of the mandible. This is time-consuming and not possible in patients with distorted mandibular contour. It is also difficult to fit the osteotomized fibula to the contoured plate. In comparison, the superiorly positioned spanning plate achieve rigid fixation of the mandible while leaving the defect completely free and unhampered by hardware, allowing space for planning osteotomies and easier fixation of the neomandible. Using this modified technique, we are able to recreate the original mandibular profile with ease.

Increased plate and osteosynthesis related complications associated with postoperative concurrent chemoradiotherapy in oral cancer

BACKGROUND

Plate osteosynthesis is a widely used technique in head and neck reconstructive surgery. The objective of this study was to determine whether postoperative chemoradiotherapy, which was recently introduced for high-risk head and neck cancer, affects plate and osteosynthesis related complications.

METHODS

Fifty-two consecutive patients, who had undergone plate osteosynthesis for mandibular reconstruction between October 2003 and September 2006, were included in the study. The patients were divided into 3 groups: (1) surgery alone (n = 19), (2) surgery with postoperative radiotherapy (n = 14), and (3) surgery with concurrent chemoradiotherapy (n = 19). Outcome measures included any bone or plate related complications.

RESULTS

The plate and osteosynthesis related complications occurred in 10.5% of patients in surgery-alone group, 28.6% in surgery with postoperative radiation group, and 63.2% in surgery with postoperative concurrent chemoradiotherapy group. The differences in the complication rates among these 3 groups were statistically significant (p = .003). In univariate analysis, postoperative radiation (p = .007) and concurrent chemotherapy (p = .003) were found to be significantly associated with complications. In multivariate analysis, only concurrent chemotherapy was found to be statistically significant (p = .002) with odds ratio of 7.72.

CONCLUSION

Postoperative concurrent chemoradiotherapy significantly increases plate and osteosynthesis related complications in oral cancer.

Use of an external fixator to stabilise the proximal mandibular segments during reconstruction

The main aims of mandibular reconstruction are to reproduce the three dimensional position of the patients' mandible with the condyles in the glenoid fossae. We describe a simple technique using an external fixator to stabilise the proximal mandibular segments during resection to aid reconstruction.

Mandibular reconstruction in 2004: an analysis of different techniques

PURPOSE OF REVIEW

The field of mandibular reconstruction has evolved dramatically over the past fifty years. Numerous advances in microsurgical technique, plating technology and instrumentation, and an understanding of donor site angiosomes have made consistent and reliable mandibular reconstruction possible. Refinements in technique continue to improve the functional and aesthetic outcomes of oromandibular reconstruction. This review discusses the current state-of-the-art techniques for mandibular reconstruction and highlights the latest innovations in technique.

RECENT FINDINGS

The most common indication for oromandibular reconstruction remains ablative surgery for advanced neoplastic processes of the oral cavity and oropharynx. Reconstruction of these complex three-dimensional composite bony and soft-tissue defects is paramount for rehabilitation of form and function. Vascularized osseous free tissue transfer is the state-of-the-art for mandibular reconstruction. The long-term excellent functional and aesthetic outcomes of this technique have recently been reported. The most commonly used free flaps for mandibular reconstruction are the fibula, iliac crest, and scapula. Each of these typically accepts endosseous implants improving functional outcomes. The use of mandibular reconstruction plates and coverage with a soft-tissue flap remains a reconstructive option for selected patients. The latest refinements in technique include temporary intraoperative external fixation, the use of periosteal free flaps, distraction osteogenesis, and development of biodegradable biopolymer scaffolds for mandibular defects.

SUMMARY

Oromandibular reconstruction, although a challenge for the head and neck reconstructive surgeon, is now reliable and highly successful with excellent long-term functional and aesthetic outcomes.

Temporary intraoperative external fixation in mandibular reconstruction

OBJECTIVES

To describe the use of a temporary intraoperative external fixation device to assist in the optimal bony reconstruction of the mandible in the setting of vascularized bone grafts.

STUDY DESIGN

A retrospective review of six patients who underwent composite resection of the mandible and subsequent reconstruction with osteocutaneous free tissue transfer in a tertiary care center.

METHODS

Six cases of mandibular reconstruction using an intraoperative external fixation system to assist the positioning of vascularized bone grafts are presented. All patients had composite resection of the mandible and subsequent reconstruction with either a scapula or fibula osteocutaneous flap. Follow-up ranged from 2 to 16 months.

RESULTS

Successful reconstruction as defined by acceptable contour, occlusion, and condylar position was achieved in all cases. Complications were limited to a postoperative cerebrovascular accident requiring anticoagulation and subsequent neck hematoma.

CONCLUSIONS

Use of intraoperative external fixation maintains the proper alignment of mandibular segments without the use of a bridging reconstruction plate. This technique is particularly valuable with tumors involving the outer cortex of the mandible.

The importance of mandibular position in microvascular mandibular reconstruction

The challenge of mandibular reconstruction rests in the difficulty of re-creating the intricate three-dimensional relationship of the oral cavity, thereby ensuring occlusal relationships, oral competence, and facial contour. Recent advances in microvascular surgery have made reliable transfer of autologous tissue possible, hut successful reconstruction depends on accurate insetting of the bone flap. The authors reviewed their five years of experience with mandibular reconstruction and found six patients with a poor reconstructive result secondary to improper insetting of the bone flap. Anteromedially rotated and free-floating proximal mandibular segments appeared to be the most significant contributor to incorrect placement of the bone flap. Based on their findings, the authors devised a simple technique for stabilizing proximal mandibular segments.

Free vascularized fascial flap in oral cavity reconstruction

Our experience with the free vascularized fascial flap based on the radial artery used for intraoral reconstruction is described. Thirteen patients underwent primary or secondary reconstruction following major resections for malignant disease. The osseofascial flap incorporating radial bone proved to be ideal when reconstruction of composite mandibular or maxillary defects was undertaken. The flaps rapidly underwent surface epithelialization, and submucosal fibrosis provided the ideal attached mucosal lining for prosthetic rehabilitation.

Fixation of vascularized bone grafts

In 24 patients, fixation of isolated or combined bone grafts has been performed exclusively with miniplates. Other than the lateral displacement of one osteomyocutaneous iliac crest graft, no complication occurred with regard to the fixation method chosen. In contrast to the clinical findings, our results of an animal experiment demonstrate less complications by fixation of vascularized bone grafts to mandibular angle defects (guinea pig) when THORP plates are used instead of miniplates. Whereas we consider miniplate fixation of vascularized bone grafts to be the method of choice, selected patients may require more stable fixation systems, especially when a high postoperative mobility may be expected or large amounts of the mandible including the condyle have to be reconstructed.

Mandibular reconstruction: experience with the free vascularized fibula transfer

Mandibular resection, following surgery for tumor or osteoradionecrosis, leaves a patient with a swallowing, speech, and cosmetic disability. Repair of the oromandibular defect is difficult and various prostheses and grafts have been used and reported. The most popular form of mandibular reconstruction is the use of the free, vascularized bone transfer. We report our experience with the free vascularized fibula bone transfer in eight patients.