Volume-length impact of lateral jaw resections on complication rates

Finite element analysis of low-profile reconstruction plates for atrophic mandibles: a comparison of novel 3D grid and conventional plate designs

OBJECTIVES

This study aimed to compare the reconstruction with type 2.4 and three-dimensional (3D) grid plates relating the areas of weakness to anatomical regions of force incidence in atrophic mandibles with and without segmentation using finite element analysis (FEA).

MATERIALS AND METHODS

Strength and force quality in the mandible were also determined. The atrophic mandible models with and without segmentation were divided into four groups, and the behavior of each plate was analyzed using finite element analysis. In the atrophic mandible without segmentation using the type 2.4 reconstruction plate, the highest stress concentration in the plate was observed in the posterior region of the mandibular body and in the grid type 3D reconstruction plate was observed in the mandibular angle.

RESULTS

In the segmented atrophic mandible with the 2.4 reconstruction plate, higher stress concentration was observed in the mandibular segment defect. Analysis of the 3D grid-like reconstruction plate revealed that the geometry of the plate conferred greater stiffness to the assembly, as the most significant stress concentration was observed at the mandibular angle.

CONCLUSION

The width of the plate design may influence the strength, not the thickness.

A novel alloplastic grid reconstruction plate for the mandible - Retrospective comparative clinical analysis of failure rates and specific complications

PURPOSE

This study aimed to investigate the effect of three different osteosynthesis plate systems on failure rates and complications after continuity-interrupting mandibular resections with alloplastic reconstructions.

MATERIALS AND METHODS

Records of respective patients from 2010 to 2020 were analyzed retrospectively. The analyses included the osteosynthesis plate type (2.4 MANDIBULAR (RP1: MANDIBULAR [Medicon®, Tuttlingen, Germany]; RP2: Modus® Reco 2.5 [Medartis®, Basel, Switzerland]; and RP3: Modus 2 Mandible [Medartis®, Basel, Switzerland]), extent & location of the defect, age, sex, radiotherapy, and nicotine abuse. In case of failure, timepoint, and the problem, namely oral/extraoral dehiscence, screw loosening, and plate fractures that led to removal, were analyzed. Complications were classified according to Clavien-Dindo system.

RESULTS

A total of 136 patients were included. The mean follow-up time was 18 ± 26 months. Survival rates after 1, 2, and 5 years were 69.9%, 66.9%, and 64.7%, respectively. Although survival was not significantly associated with the reconstruction system, the most frequent complications were seen in cases of RP1 & RP2 when compared to RP3 (p = 0.033). In brief, dehiscences were seen significantly less often in cases of RP3 (12.5%) when compared to RP1 (44.7%) and RP2 (26.9%; p = 0.024). Fractures of the osteosynthesis systems occurred in 3 of 4 cases (75%) with RP1, in 1 of 4 cases (25%) using RP2, and in no single case using the RP3 system (p = 0.03). Most of the observed complications occurred up to 12 months postoperatively. A total plate survival rate of 64.7% and a total plate complication rate of 47.8% were seen.

CONCLUSION

In conclusion, it seems that RP3 should be preferred over RP1 and RP2 regarding failure rates and complications.

MRONJ of the Mandible—From Decortication to a Complex Jaw Reconstruction Using a CAD/CAM-Guided Bilateral Scapula Flap

Medication-related osteonecrosis of the jaw (MRONJ) has been an integral part of the maxillofacial patient population for some time. The therapeutic concept ranges from conservative approaches over less extended decortications to major jaw resections, which can result in a considerable loss of quality of life. Based on three case reports, this paper presents the long-term history of patients with MRONJ of the mandible, whose disease ultimately resulted in partial or total mandibular resection and subsequent multisegmental reconstruction using a microvascular anastomosed bone flap. Furthermore, a suitable alternative for complex mandibular reconstruction is demonstrated when using a free fibula flap is not possible. The options are limited, particularly when multisegmental restoration of mandibular continuity is required. One case presents a mandible reconstruction using a CAD/CAM-guided bilateral scapular free flap (CAD/CAM = Computer-Aided Design and Manufacturing), which has not been described for this purpose before. Due to the complexity, computer-assisted surgery and patient-specific implants seem reasonable, which is why a special focus was applied to this topic.

Plate-related complication and health-related quality of life after mandibular reconstruction by fibula flap with reconstruction plate or miniplate versus anterolateral thigh flap with reconstruction plate

BACKGROUND

Plate-related complications are major long-term complications in mandible reconstruction. There are controversies regarding the use of a reconstruction plate versus miniplates and a bone flap versus a soft tissue flap with a bridging plate. Direct comparisons of a fibula flap and an anterolateral thigh flap, the applicability between a reconstruction plate and miniplate, and the correlation between plate-related complications and quality of life remain unclarified. Therefore, this study aimed to the explore complications of different flaps and plates and how they impact the patients' quality of life.

METHODS

We retrospectively reviewed the medical records of a total of 205 patients aged >18 years who underwent segmental mandibulectomy and reconstruction using fibula flap with reconstruction plate (FR; n = 86), fibula flap with miniplate (FM; n = 61), and anterolateral thigh flap with reconstruction plate (AR; n = 58) due to cancer ablation, osteoradionecrosis, or benign tumor excision between August 2010 and December 2019. Data on characteristics, complications, and health-related quality of life were collected and analyzed.

RESULTS

The plate-related complication rate was the highest in the AR group (37.9%), then in the FR group (25.6%), and was the lowest in the FM group (13.1%; p = 0.0079). The plate exposure rate was the highest in the AR group (24.1%), then in the FR group (15.7%), and was the lowest in the FM group (4.9%; p = 0.0128). The plate fracture and dislodge rates for the AR group were both higher than those for the FR and FM groups (24.1% versus 9.3% versus 9.8%, respectively; p = 0.023). The AR group had worse complication-free survival (hazard ratio [HR]: 3.61, 95% CI: 1.99-6.56, and p < 0.0001) than the FR and FM groups. Osteoradionecrosis (HR: 6.19, 95% CI: 2.11-18.21, and p = 0.0009) and postoperative radiotherapy (HR: 2.87, 95% CI: 1.34-6.12, and p = 0.0402) were both independent adverse factors for complication-free survival, whereas patient treated primarily (HR: 0.35, 95% CI: 0.17-0.73, and p = 0.0048) was an independent protective factor. Plate-related complication negatively impacted the quality of life based on pain scores (β: -0.56, SE: 0.26, and p = 0.034).

CONCLUSIONS

Using a fibular flap fixed with miniplates and avoiding the use of a reconstruction plate may yield a reduced plate exposure rate and better health-related quality of life, particularly for patients with osteoradionecrosis or those who need postoperative radiotherapy.

Quantification of the Bimodal Plate-Specific Complication Profile Associated With Reconstruction of Segmental Mandibular Defects With Reconstruction Plate and Soft Tissue Flap: Evidence From Systematic Review

ABSTRACT

Reconstruction of segmental mandibular defects with a mandibular reconstruction plate and separate soft tissue flap can be indicated in certain patients. Whilst this technique can provide acceptable results, its exact longevity and timing of associated complications is poorly understood. This study was designed to quantify and plot in time the complication profile associated with this technique of mandibular reconstruction.A search of the Medline and PubMed Central databases was conducted using the terms "Mandibulectomy" and "Reconstruction Plate." Articles reporting total number of plate extrusions and fractures and their postoperative timing were included.Nine articles were included, representing 265 patients with mandibulectomy defects reconstructed using mandibular reconstruction plates. Of these, 135 were male (62%) and 82 were female (38%). The mean age was 59 years. The predominant pathology was oral cavity Squamous Cell Carcinoma (SCC) (80%). Seventy-three patients (28%) experienced complications (mean follow-up: 24 months), with median time to complication of 3 months. Forty-three plate extrusions (16%), 20 plate fractures (8%) and 10 cases of loosened screws (4%) were reported. A bimodal temporal distribution of complications was found.Overall, a plate-specific complication rate of 28% was found, confirming a higher incidence of complications in comparison to osseous free flap reconstruction. These occur over a bimodal time distribution, with extrusion occurring earlier than fracture. Interference with speech, swallow and dental rehabilitation, and delay of adjuvant therapy are potential consequences. These findings indicate that patients may be better served by more complex reconstructive procedures, to minimize exposure to a frequent and prolonged complication profile.

Biomechanical evaluation of caudally and buccally screwed customised reconstruction plates for lateral segmental defects of mandible

The aim of this study was to compare locking reconstruction plates with caudobuccally screwed custom mandibular reconstruction plates in bridging lateral mandibular segmental defects. The in vitro study was conducted on 13 polyurethane mandibles. A total of 7 mandibles with lateral segmental defects were bridged with locking reconstruction plates in group I, 6 mandibles with the same standard defect were bridged with caudobuccally screwed customised reconstruction plates in group II. Mean yield displacement, yield load, and displacement at 80 N (Newtons), 100 N, 200 N, 300 N loading were compared among the 2 groups. The mean (SD) displacement for Group I was 11.27 (3.6) mm, Group II was 21.08 (2.5) mm. Group II had significantly greater (p=0.0001) displacement when compared with Group I. The mean (SD) force before failure for Group I was 638.4 N (127.2), Group II was 1398. 3 N (162.7). Group II withstood significantly greater force than Group I (p=0.0001). The study reveals that the caudobuccally screwed custom reconstruction plates can significantly enhance yield load as preserving the preoperative shape of the face and mandible.

Evaluating the use of anterolateral thigh flaps to prevent reconstruction plate exposure in patients with oral cancer

OBJECTIVE

Plate exposure remains one of the most serious complications of oromandibular reconstruction. The purpose of this study was to investigate the effect of wrapping reconstruction plates with anterolateral thigh (ALT) free flaps as a way to prevent plate exposure.

STUDY DESIGN

A total of 91 patients with composite oromandibular defects who underwent surgical reconstruction using a reconstruction plate in conjunction with an ALT musculocutaneous flap were recruited. The participants were divided into 2 groups, based on whether the plate was wrapped with or covered by the ALT flap.

RESULTS

The incidence of plate exposure in the experimental group (17%) was significantly lower than that of the control group (43.1%; P < .0001). The mean time from reconstruction until plate exposure in the experimental group was 19.4 ± 23.6 months, whereas the mean time in the control group was 12.3 ± 9.1 months. In the logistic regression model for the occurrence of plate exposure, the only factor found to be associated with plate exposure was how the ALT flap was used (P = .026).

CONCLUSIONS

The results of the present study indicate that wrapping the reconstruction plate with an ALT flap decreased the incidence of plate exposure in patients with oromandibular defects.

Association of Plate Contouring With Hardware Complications Following Mandibular Reconstruction

OBJECTIVES/HYPOTHESIS

Despite considerable effort being dedicated to contouring reconstruction plates, there remains limited evidence demonstrating an association between contour and reconstructive outcomes. We sought to evaluate whether optimizing mandibular reconstruction plate contouring is associated with reduced postoperative hardware complications.

STUDY DESIGN

Retrospective cohort study.

METHODS

A cohort study was performed with adult patients (age ≥18 years) who underwent mandibulectomy and osseous free flap reconstruction following oncologic ablation at the University Health Network in Toronto, Canada, between January 1, 2003 and December 31, 2014. Patients with computed tomography scans performed within 1 year of reconstruction were included. Computer-based three-dimensional models were generated and used to calculate the mean plate-to-bone gap (mm). The primary outcome was plate exposure. Secondary outcome included a composite of plate exposure or intraoral dehiscence. Logistic regression models were fitted for each outcome accounting for other patient and surgical characteristics associated with the primary outcome.

RESULTS

Ninety-four patients met inclusion criteria, with a mean age of 60.4 (standard deviation [SD] 14.9). The mean follow-up time was 31.4 months (range 3-94). Reconstruction was performed with fibular (57%) and scapular free flaps (43%). In the multivariable model, small mean plate-to-bone gap (<1 mm) was independently associated with 86% reduced odds of plate exposure (odds ratio [OR] 0.12; 95% confidence interval [CI] 0.02-0.55). Mean plate-to-bone gap less than 1 mm was also independently associated with reduced odds of developing a composite of plate exposure or intraoral dehiscence (OR, 0.29; 95%CI, 0.11-0.75).

CONCLUSION

Optimizing plate contouring during mandibular reconstruction may decrease the development of postoperative hardware complications.

LEVEL OF EVIDENCE

IV Laryngoscope, 2021.

Biomechanical In Vitro Study on the Stability of Patient-Specific CAD/CAM Mandibular Reconstruction Plates: A Comparison Between Selective Laser Melted, Milled, and Hand-Bent Plates

Study Design

An experimental in vitro study.

Objective

Plate fractures are a recurrent problem in alloplastic mandibular reconstruction. Hypothetically it can be assumed that computer-aided design (CAD)/computer-aided manufacturing (CAM) reconstruction plates have a higher stability than conventional hand-bent plates. The aim of the study was to compare additive and subtractive fabricated CAD/CAM mandibular reconstruction plates as well as conventional plates with regard to their biomechanical properties.

Methods

In a chewing simulator, plates of 2 conventional locking plate systems and 2 CAD/CAM-fabricated plate systems were compared. The plates were loaded in a fatigue test. The maximum number of cycles until plate fracture and the plate stiffness were compared.

Results

While all conventional plates fractured at a maximum load between 150 and 210 N (Newton) after a number of cycles between 40 000 and 643 000, none of the CAD/CAM plates broke despite a nearly doubled load of 330 N and 2 million cycles. Both CAD/CAM systems proved to be significantly superior to the hand-bent plates. There was no difference between the 2 CAD/CAM systems.

Conclusions

Concerning the risk of plate fracture, patient-specific CAD/CAM reconstruction plates appear to have a significant advantage over conventional hand-bent plates in alloplastic mandibular reconstruction.

Complications After Soft Tissue With Plate vs Bony Mandibular Reconstruction: A Systematic Review and Meta-analysis

OBJECTIVE

Mandibular reconstruction for segmental defects is a well-studied topic. However, there are conflicting data on the risks of delayed plate-related complications. The objective of this systematic review and meta-analysis was to assess long-term plate-related complications following reconstruction of the mandible with soft tissue and a plate as compared with immediate vascularized bony reconstruction.

DATA SOURCES

A medical librarian created search strategies with a combination of keywords and controlled vocabulary in Ovid Medline (1946-), Embase (1947-), Scopus (1960-), Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews, and Clinicaltrials.gov.

REVIEW METHODS

Candidate articles were independently reviewed by 2 authors. Inclusion/exclusion criteria were uniformly applied. Articles were considered eligible if they included adequate reporting of plate extrusion and/or fracture and had follow-up ≥12 months.

RESULTS

A total of 2379 patients were included. The risk of plate fracture was low in cases of soft tissue with a plate (5%; 95% CI, 0.03-0.08) and osseous reconstruction (1%). The risk of extrusion following soft tissue and plate reconstruction was 20% (95% CI, 0.15-0.27). In the osseous reconstruction group, the risk of extrusion was 10% (95% CI, 0.06-0.18). Revision surgery was performed twice as often following soft tissue with a plate as compared with vascularized bony reconstruction (32% [95% CI, 0.25-0.40] vs 14% [95% CI, 0.09-0.21], respectively).

CONCLUSION

Delayed plate-related complications remain a significant problem following segmental defect reconstruction. Soft tissue and plate reconstruction techniques may increase the risk of plate removal and revision surgery.

Lateral segmental mandibulectomy reconstruction with bridging reconstruction plate and anterolateral thigh free flap: a case series of 30 consecutive patients

Lateral posterior segmental mandibular defects present a reconstructive challenge and an osseous flap would be the gold standard to reconstruct such a defect. However, combining a mandibular reconstruction plate (MRP) with a soft-tissue free flap (to restore mucosal integrity and provide durable coverage of the plate itself) offers an alternative option for posterior segmental mandibular defects in patients who are not suitable for osseous reconstruction, or do not choose it. We retrospectively reviewed 30 consecutive patients (19 male and 11 female) who underwent reconstruction of a segmental mandibulectomy defect using a bridging MRP and anterolateral thigh (ALT) free flap. The mean (range) age was 67 (31-87) years. The American Society of Anesthesiologists' (ASA) status of the study population comprised Grade 1 (n = 10), Grade 2 (n = 18), and Grade 3 (n = 2). The majority of patients had oral cavity squamous cell carcinoma (n = 26) involving the mandible, two had osteoradionecrosis, and two mucoepidermoid carcinoma. Four patients had complications specific to the reconstruction, and flap loss occurred in one (96.7% success rate). Metalwork infection occurred in three, including one plate extrusion and one plate fracture. The median length of stay was 10 days, and mean (range) duration of follow up 23.3 (1-96) months. This technique is an alternative reconstructive option for the non-tooth-bearing mandible. Reconstructing a posterolateral segmental mandibulectomy defect with a bridging MRP and ALT free flap offers a robust reconstructive alternative with a favourable complication profile.

Evaluation of a novel osteosynthesis plate system for mandibular defects

Continuity defects of the jaw can be reconstructed with titanium plates or microvascular bone flaps; osteosynthesis plates are necessary for both. In this study we performed a retrospective review of patients treated with Medartis MODUS® Mandible Trauma/Reco 2.0-2.5, TriLock bridging plates, mandibulectomy and soft tissue free flap or reconstruction with a bony free flap and TriLock mandibular plates from the same system from January 2015 to August 2019. The variables recorded were sex, age, diagnosis, radiotherapy, date of implantation, date of explantation or death of patient, size of mandibular defect, Jewer classification of defect, number of screws used, segments of bony reconstruction, screws per segment, plate exposure, plate breakage, and pseudarthrosis. The bridging plate group consisted of 41 patients, while the mandibular plate group consisted of 24 patients. The percentage of plate exposure was 17.07% for the bridging plate group and 4.17% for the mandibular plate group. Plate breakage was 0 in both groups. Pseudarthrosis was 4.17% in the mandibular plate group. In the bridging plate group, an anterolateral thigh flap covered all exposures. Of 7 plate exposures, 4 were found in a C defect. The complication rate of the investigated plates was lower than the complication rates of other plate systems.

Mandible handling in the surgical treatment of oral squamous cell carcinoma: lessons from clinical results after marginal and segmental mandibulectomy

OBJECTIVE

The aim of this retrospective, single-center study was to analyze long-term results after marginal and segmental mandibulectomies in patients with oral squamous cell carcinoma (OSCC).

STUDY DESIGN

The study included 259 patients treated for OSCC with mandibulectomy between 1996 and 2010. Data acquisition consisted of analysis of operation reports, re-evaluation of histologic bone specimens, and collection of clinical follow-up data.

RESULTS

Of the included patients, 86.5% had received segmental and 13.5% marginal mandibulectomies. Patients who received segmental mandibulectomy generally displayed a higher TNM (tumor-node-metastasis) stage; 47% of patients who received segmental mandibulectomy and 14% of those receiving marginal mandibulectomy showed bone infiltration (pT4 a). Of all patients with bone infiltration, 49% showed an invasive histologic infiltration pattern, and 35% showed an erosive histologic infiltration pattern. We found healthy residual crestal bone height in 43% of all segmental mandibulectomies. Only 8% of all patients were prosthodontically rehabilitated. With regard to prognostic parameters, there was no significant difference between patients receiving marginal mandibulectomy and those receiving segmental mandibulectomy.

CONCLUSIONS

Because healthy residual crestal bone height was found in 43% of all patients who had received segmental mandibulectomies, it is conceivable that a significant number of patients would profit from marginal mandibulectomy, at least in cases of absent or erosive bone infiltration pattern, because the residual crestal bone is functionally stable.

The effect of fixation plate use on bone healing during the reconstruction of mandibular defects

Objectives

This study sought to compare efficiency results between the use of a customized implant (CI) and a reconstruction plate (RP) in mandibular defect reconstruction in an animal model.

Materials and Methods

Fifteen rabbits underwent surgery to create a defect in the right side of the mandible and were randomly divided into two groups. For reconstruction of the mandibular defect, the RP group (n=5) received five-hole mini-plates without bone grafting and the CI group (n=10) received fabricated CIs based on the cone-beam computed tomography (CBCT) data taken preoperatively. The CI group was further divided into two subgroups depending on the time of CBCT performance preoperatively, as follows: a six-week CI (6WCI) group (n=5) and a one-week CI (1WCI) group (n=5). Daily food intake amount (DFIA) was measured to assess the recovery rate. Radiographic images were acquired to evaluate screw quantity. CBCT and histological examination were performed in the CI subgroup after sacrifice.

Results

The 1WCI group showed the highest value in peak average recovery rate and the fastest average recovery rate. In terms of reaching a 50% recovery rate, the 1WCI group required the least number of days as compared with the other groups (2.6±1.3 days), while the RP group required the least number of days to reach an 80% recovery rate (7.8±2.2 days). The 1WCI group showed the highest percentage of intact screws (94.3%). New bone formation was observed in the CI group during histological examination.

Conclusion

Rabbits with mandibular defects treated with CI showed higher and faster recovery rates and more favorable screw status as compared with those treated with a five-hole mini-plate without bone graft.

A small number of residual teeth after the mandibular resection of oral cancer is associated with titanium reconstruction plate exposure

Objective

Reconstruction plates are used to treat patients with a segmental mandibular defect after oral cancer surgery. Reconstruction plate failure analysis has rarely focused on occlusion, which conducts a mechanical force to the mandible and the plate. To determine the prognostic factors, we retrospectively evaluated patients who underwent reconstruction of a mandibular segmental defect with a reconstruction plate and assessed the number of residual paired teeth.

Material and Methods

From among 390 patients with oral cancer who visited University of Tsukuba Hospital (Tsukuba, Japan) between 2007 and 2017, we selected and analyzed the data of 37 patients who underwent segmental resection of the mandible and reconstruction with reconstruction plates. Prognostic factors evaluated were patient age, sex, TNM classification, plate manufacturer, treatment with radiotherapy or chemotherapy, whether the patient had diabetes or smoked, and whether the patient had a small number of residual paired teeth, plate length, and use of a fibular‐free flap. Among these 37 patients, eight reconstruction plates had intraoral or extraoral exposure and were removed in 5 years.

Results

Kaplan–Meier and log‐rank analyses revealed that the prognosis for the 5‐year plate exposure‐free rate was significantly poorer for patients with a small number of residual teeth than for patients with no teeth or those with a large number of residual teeth (.01). Univariate Cox regression analysis revealed that a small number of residual teeth was a significant prognostic factor in the loss of a reconstruction plate (hazard ratio: 5.63; 95% confidence interval [1.10, 25.85]; .04).

Conclusions

A small number of residual teeth after the segmental resection of oral cancer is significantly involved in reconstruction plate survival and may be important in predicting reconstruction plate prognosis.

Surgical site infections following oral cavity cancer resection and reconstruction is a risk factor for plate exposure

Background

Plate-related complications following head and neck cancer ablation and reconstruction remains a challenging problem often requiring further management and reconstructive surgeries. We aim to identify an association between surgical site infections (SSI) and plate exposure.

Methods

A retrospective study between 1997 and 2014 was performed to study the association between postoperative SSI and plate exposures. Eligible patients included those with a history of oral squamous cell carcinoma who underwent surgical resection, neck dissection, and free tissue reconstruction. Demographic and treatment related information was collected. SSI were classified based on CDC definition and previously published literature. Univariable analysis on demographic factors, smoking history, diabetes, radiation, surgical and hardware related factors; while multivariable analysis on SSI, plate height, segmental mandibulectomy defects and radiation were conducted such as using cox proportional hazard models.

Results

Three hundred sixty-five patients were identified and included in our study. The mean age of the study group was 59.2 (+/−13.8), with a predominance of male patients (61.9%). 10.7% of our patient cohort had diabetes, and another 63.8% had post-operative radiation therapy. Patients with SSI were more likely to have plate exposure (25 vs. 6.4%, p <0.001). Post-operative SSI, mandibulectomy defects, and plate profile/thickness were associated with plate exposure on univariable analysis (OR = 5.72, p < 0.001; OR = 2.56, p = 0.014; OR = 1.44, p = 0.003 respectively) and multivariable analysis (OR = 5.13, p < 0.001; OR = 1.36, p = 0.017; OR = 2.58, p = 0.02 respectively).

Conclusion

Surgical site infections are associated with higher rates of plate exposure. Plate exposure may require multiple procedures to manage and occasionally free flap reconstruction.

Biomechanical analysis of a curvilinear distractor device for correcting mandibular symphyseal defects

PURPOSE

The local mechanical environment is a determinant of successful transport disc distraction osteogenesis. This study assessed the biomechanics of a curvilinear distractor device for correcting mandibular symphyseal defects.

MATERIALS AND METHODS

The finite element method was used to analyze an intact mandible, mandibular distractor bodies with different rail thicknesses (4, 6, 8, and 10 mm), and mandibular distractor bodies with rails and auxiliary lingual brackets.

RESULTS

Rail thickness was positively correlated with maximum von Mises stress in the distractor and negatively correlated with maximum displacement of the mandibular distractor bodies. The maximum von Mises stress occurred at the junction of the rails and fixed arms. It also exceeded the yield strength of the titanium material. Compared with the maximum displacement of the intact mandible, that of the mandibular distractor bodies was visibly increased.

CONCLUSION

An auxiliary lingual bracket can effectively decrease stress in such devices and displacement of mandibular distractor bodies. Rail fixation alone cannot achieve stability for distraction osteogenesis. Using an auxiliary lingual bracket effectively prevents distractor breakage and exposure.

Hardware removal after osseous free flap reconstruction

OBJECTIVE

Identifying risk factors for hardware removal in patients undergoing mandibular reconstruction with vascularized osseous free flaps remains a challenge. The purpose of this study is to identify potential risk factors, including osteocutaneous radial forearm versus fibular flap, for need for removal and to describe the fate of implanted hardware.

STUDY DESIGN

Case series with chart review Setting Academic tertiary care medical center.

SUBJECTS AND METHODS

Two hundred thirteen patients undergoing 227 vascularized osseous mandibular reconstructions between the years 2004 and 2012. Data were compiled through a manual chart review, and patients incurring hardware removals were identified.

RESULTS

Thirty-four of 213 evaluable vascularized osseous free flaps (16%) underwent surgical removal of hardware. The average length of time to removal was 16.2 months (median 10 months), with the majority of removals occurring within the first year. Osteocutaneous radial forearm free flaps (OCRFFF) incurred a slightly higher percentage of hardware removals (9.9%) compared to fibula flaps (6.1%). Partial removal was performed in 8 of 34 cases, and approximately 38% of these required additional surgery for removal.

CONCLUSION

Hardware removal was associated with continued tobacco use after mandibular reconstruction (P = .03). Removal of the supporting hardware most commonly occurs from infection or exposure in the first year. In the majority of cases the bone is well healed and the problem resolves with removal.

Composite mandibulectomy: a novel animal model

OBJECTIVES

Segmental mandibular defects can result after the treatment of various pathologic processes, including osteoradionecrosis, tumor resection, or fracture nonunion with sequestration. The variety of etiologies and the frequency of occurrence make the reconstruction of segmental mandibular defects a topic of significant interest. Despite these incentives, a well-established small-animal model of the segmental mandibulectomy, including composite resection, does not exist. The objective of this study is the creation of a reliable animal model that can be used to study the reconstruction of en bloc mandibular defects. Surgical techniques and an array of reconstructive options are described.

STUDY DESIGN

Description of an animal model.

SETTING

Animal laboratory at a quaternary care university medical center.

METHODS

We present an Animal Research Oversight Committee-approved prospective analysis of survival operations in the rat model. A detailed, stepwise description of surgical technique and relevant intraoperative anatomy is presented. Postoperative management, early pitfalls, surgical complications, and future applications are discussed.

RESULTS

A total of 72 operations were performed by a single individual between July and October 2010. Two intraoperative and 9 postoperative complications were recognized. There were 6 orocutaneous fistulas, 2 abscesses, and 1 seroma. There were 4 fatalities, which were attributed to anesthetic complications (2, intraoperative), hematoma formation (1, postoperative), and foreign-body aspiration (1, postoperative).

CONCLUSION

This novel animal model reliably replicates the en bloc segmental mandibular defects seen in our patient population and can be manipulated to achieve a wide variety of research objectives.

Mandibular reconstruction using AO/ASIF stainless steel reconstruction plate: a retrospective study of 36 cases

AIM

The study was aimed at esthetic and functional results as well as patient tolerance after reconstruction with reconstruction plate. The follow-up ranged from 1 to 4 years.

MATERIALS AND METHODS

A retrospective study of 36 patients who had mandibular reconstruction with AO/ASIF stainless steel reconstruction plates after oncologic resection was evaluated. The indications and postoperative outcomes were studied.

RESULTS

At the end of study, 24 of 36 patients (67%) still had the plate in place. Around three (8%) plates were fractured. Nine (25%) plates got exposed leading to surgical intervention. Surgical results were satisfying, particularly when looking at delayed healing or long-term tolerance. Esthetic (79% rated results as good or acceptable) and functional results of this reconstruction were satisfying.

CONCLUSION

We conclude by saying that reconstruction plate provides a solution for safe and rapid mandibular reconstruction for patients with poor prognosis or poor condition. This method also preserves the possibility of secondary reconstruction.

CLINICAL SIGNIFICANCE

The reconstruction plate may be a good clinical choice for safe and rapid mandibular reconstruction.

Free flap reconstruction of lateral mandibular defects: indications and outcomes

OBJECTIVE

To compare outcomes following osteocutaneous radial forearm and fibula free flap reconstruction of lateral mandibular defects.

STUDY DESIGN

Retrospective case-controlled study.

SETTING

Historical cohort study.

SUBJECTS AND METHODS

All patients who underwent free flap reconstruction of lateral mandibular defects from 1999 to 2010 were included in this study. Patients were classified into 2 groups based on type of reconstruction: (1) osteocutaneous radial forearm (n = 73) and (2) fibula free flap reconstruction (n = 51). Patient characteristics, length of hospital stay, recipient and donor site complications, and long-term outcomes including postoperative diet were evaluated.

RESULTS

Most patients were male (68%) and presented with advanced T-stage (71%) squamous cell carcinoma (94%) involving the alveolus (21%), retromolar trigone (23%), or oral tongue (21%). Median length of hospital stay was 8 days (range, 4-22 days). The recipient site complication rate approached 27% and included infection (n = 11), mandibular malunion (n = 9), exposed bone or mandibular plates (n = 9), and flap failure (n = 5). Most patients demonstrated little to no trismus following reconstruction (94%) and were able to resume a regular or edentulous diet (73%). No difference in complication rates or postoperative outcomes was seen between osteocutaneous radial forearm and fibula free flap groups (P > .05). One patient underwent dental implantation following osteocutaneous radial forearm free flap reconstruction. No patients from the fibula free flap group underwent dental implantation.

CONCLUSION

The osteocutaneous radial forearm and fibula free flap provide equivalent wound healing and functional outcomes in patients undergoing lateral mandibular defect reconstruction.

Comparison of bone morphogenetic protein-2 and osteoactivin for mesenchymal cell differentiation: effects of bolus and continuous administration

Current osteoinductive protein therapy utilizes bolus administration of large doses of bone morphogenetic proteins (BMPs), which is costly, and may not replicate normal bone healing. The limited in vivo biologic activity of BMPs requires the investigation of growth factors that may enhance this activity. In this study, we utilized the C3H10T1/2 murine mesenchymal stem cell line to test the hypotheses that osteoactivin (OA) has comparable osteoinductive effects to bone morphogenetic protein-2 (BMP-2), and that sustained administration of either growth factor would result in increased osteoblastic differentiation as compared to bolus administration. Sustained release biodegradable hydrogels were designed, and C3H10T1/2 cells were grown on hydrogels loaded with BMP-2 or OA. Controls were grown on unloaded hydrogels, and positive controls were exposed to bolus growth factor administration. Cells were harvested at several time points to assess osteoblastic differentiation. Alkaline phosphatase (ALP) staining and activity, and gene expression of ALP and osteocalcin were assessed. Treatment with OA or BMP-2 resulted in comparable effects on osteoblastic marker expression. However, cells grown on hydrogels demonstrated osteoblastic differentiation that was not as robust as cells treated with bolus administration. This study shows that OA has comparable effects to BMP-2 on osteoblastic differentiation using both bolus administration and continuous release, and that bolus administration of OA has a more profound effect than administration using hydrogels for sustained release. This study will lead to a better understanding of appropriate delivery methods of osteogenic growth factors like OA for repair of fractures and segmental bone defects.

Free vascularized flaps for reconstruction of the mandible: complications, success, and dental rehabilitation

PURPOSE

To evaluate complications and success of mandibular reconstruction with free fibula flaps, iliac crest flaps, and forearm flaps with reconstruction plates and to evaluate dental rehabilitation after these reconstructions.

PATIENTS AND METHODS

Eighty-three patients with segmental mandibular defects were included. Correlation analyses were used to determine the relationship between reconstruction type and clinical parameters with recipient-site complications and success. The dental rehabilitation was evaluated in successfully reconstructed survivors.

RESULTS

Multivariate analyses showed significant correlations between flap type and success (P < .0001). Of the patients, 51 (61%) were alive 2 years after the reconstruction. Mandibular reconstruction with a free forearm flap and reconstruction plate was associated with higher complication rates at the recipient site and higher failure rates compared with reconstruction with free vascularized bone flaps. Of the 32 successfully reconstructed survivors, 14 (44%) had a complete dental rehabilitation, of which 10 had dental implants and 4 did not. Only 6 (29%) of the edentulous survivors ultimately had an implant-supported prosthesis.

CONCLUSIONS

Reconstruction of the mandible with a free vascularized bone flap is superior to reconstruction with a free forearm flap with a reconstruction plate. Complete dental rehabilitation was reached in fewer than half of the surviving patients.

Biomechanics of mandibular reconstruction: a review

Knowledge of the biomechanics of the mandible allows the surgeon to understand the forces acting on the mandible during function and the resulting deformation that can occur. This allows the appropriate selection and placement of osteosynthesis plates to neutralize these forces. Many methods have been proposed for mandibular reconstruction, each of which has strengths and weaknesses. Most papers evaluating these techniques have focused on survival rates and the quality of the grafted bones, and there have been few studies of the biomechanics (stress distribution and strength) of the various types of reconstructed mandibles. This paper reviews the biomechanics of the mandible and the various methods of reconstruction reported in past studies.

Adaquate fixation of plates for stability during mandibular reconstruction

PURPOSE

To determine the most appropriate plate fixation for dispersing the stress around screws in mandibular reconstruction.

MATERIAL AND METHODS

Forty-eight three-dimensional reconstructed mandibular models with Central (C) or right Lateral (L) defects were created and divided into three groups, fixed with: (1) two screws on each side, (2) three screws on the left side with the third (middle one) located distally, or (3) three screws on the left side with the third (middle one) located proximally. A 300N vertical load was applied to the left molar region. The maximum stress was calculated using a finite element method and statistically evaluated.

RESULTS

Stress was concentrated around the screw at the distal end of the mandibular halves on the loaded side ('crucial screw'). For the C defect, stress concentrated around the 'crucial screw' was greater when there were only two screws for fixation (20.55MPa) than when there were three screws (16.17MPa; p=0.022). No significant difference was found between the two groups with three screws for fixation. For the L defect on the other hand, stress on the 'crucial screw' was relatively greater when there were three screws for fixation (18.9MPa) than when there were only two screws for (12.83MPa; p=0.051). No significant difference was found between the two groups with three screws for fixation. As for the reconstruction plate, the stresses on the plates were not different among the various screw groups for fixation nor among the C and L defects.

CONCLUSION

This paradoxical result is explained by plate bowing. Thus in large defects screw positions should take into consideration the potential for plate bowing.

The Surgical Management of Oral Cancer

Oral cavity cancers represent an area of head and neck oncology with some unique and interesting management themes. In spite of a significant paradigm shift in the treatment of many head and neck cancers toward us-ing primary chemoradiation, this treatment is not frequently applied to the oral cavity. Small cancers of the oral cavity are usually managed by surgery alone. Larger cancers are usually treated with primary surgery followed by chemoradiation. Neck treatment is offered to patients who have a greater than 20% chance of having lymph node metastasis or who have neck disease at the time of presentation. Neck treatment may involve surgery, radiation therapy, or both. Reconstruction of surgical defects of the oral cavity runs the gamut of techniques from the most simple to the most complex three-dimensional microvascular composite flaps. A multidisciplinary setting with a tumor board and multiple supportive services provides the best care for patients who have advanced-stage cancers.

Mandibular reconstruction using the titanium functionally dynamic bridging plate system: a retrospective study of 34 cases

PURPOSE

We sought to examine the use of the Titanium Functionally Dynamic Bridging Plate System (Howmedica Leibinger, Freiburg, Germany) for mandibular reconstruction after oncologic resection in 34 patients.

PATIENTS AND METHODS

A retrospective study of 34 patients who had mandibular reconstruction using the titanium dynamic bridging plate system for mandibular reconstruction after oncologic resection were evaluated. The indications and postoperative outcomes were studied. Our evaluation focuses on the tolerance and aesthetic and functional results of this system.

RESULTS

The follow-up ranged from 1 to 4 years. At the end of the study, 18 of the 34 patients (53%) still had the plate in place. One plate fracture and 1 plate exposure requiring surgical management were found. Surgical results were satisfying, particularly when looking at healing delay or long-term tolerance. Aesthetic (79% rated the results as good or acceptable) and functional results of this reconstruction material were satisfying.

CONCLUSION

This reconstruction system provides a solution for a safe and rapid mandibular reconstruction for patients with a poor prognosis or poor general condition. This method also preserves the possibility of secondary reconstruction.

Microvascular flap reconstruction of the mandible: A comparison of bone grafts and bridging plates for restoration of mandibular continuity

OBJECTIVE: To compare the efficacy of vascularized bone grafts and bridging mandibular reconstruction plates for restoration of mandibular continuity in patients who undergo free flap reconstruction after segmental mandibulectomy.

STUDY DESIGN AND SETTING. A total of 210 patients underwent microvascular flap reconstruction after segmental mandibulectomy. The rate of successful restoration of mandibular continuity in 151 patients with vascularized bone grafts was compared to 59 patients with soft tissue free flaps combined with bridging plates.

RESULTS: Mandibular continuity was restored successfully for the duration of the follow-up period in 94% of patients who received bone grafts compared with 92% of patients with bridging mandibular reconstruction plates. This difference was not statistically significant. In patients who received bone grafts, most cases of reconstructive failure occurred during the perioperative period and were due to patient death or free flap thrombosis. In patients who received bridging plates, all instances of reconstructive failure were delayed for several months and were due to hardware extrusion or plate fracture.

CONCLUSIONS: Vascularized bone-containing free flaps are preferred for reconstruction of most segmental mandibulectomy defects in patients undergoing microvascular flap reconstruction. However, use of a soft tissue flap with a bridging mandibular reconstruction plate is a reasonable alternative in patients with lateral oromandibular defects when the nature of the defect favors use of a soft tissue free flap.

SIGNIFICANCE: Both bone grafts and bridging plates represent effective methods of restoring mandibular continuity following segmental mandibulectomy, with the former being the preferred technique for patients undergoing microvascular reconstruction.

The indications and outcomes in the use of osteocutaneous radial forearm free flap

INTRODUCTION

Whether secondary to cancer surgery ablation or trauma, surgeons are faced with defects of the mandible or maxilla that would be best reconstructed with a thin, pliable soft tissue component and vascularized bone. A subset of these challenging wounds do not require the bicortical bone necessary to reestablish structural integrity or to retain a dental prosthesis, because the soft tissue needs are more critical than the bony needs. It is this niche that the radial forearm osteofaciocutaneous free flap (RFOFF) fulfills well. In the past, potential and real donor site morbidity has precluded the routine use of this flap. New methods to reduce this morbidity have rekindled our use of this flap. PROCEDURES USED: A retrospective review of patients with defects of the mandible or maxilla treated with the RFOFF from July 1, 1997, to December 31, 2000, was performed. After flap harvest, the donor site was rigidly fixated. A skin graft was placed, and a volar splint was applied for 7 days. The arm was then fully mobilized. Parameters examined were defect location, donor site complications, flap survival, fistula occurrence, plate fracture, and/or extrusion.

RESULTS

Thirty-four patients were reconstructed with the RFOFF with a follow-up of 10-54 months. Seven patients had an anterior maxillectomy defect, and 27 patients had a lateral mandibulectomy defect with associated tongue/tonsillar fossa and/or palate defect. There were no cases of flap failure or donor site radius fracture. During the follow-up period, there were no plate fractures or intraoral exposures as evidenced by clinical and radiographic evaluation. Fistulas occurred in five patients; all healed without surgical intervention.

CONCLUSION

With rigid fixation of the residual radius, donor site morbidity has been minimized, and indications for this flap have expanded. Specifically the anterior maxillary arch and the ascending ramus, angle, and posterior body of the mandible (nontooth-bearing areas) are the sites most amenable to the thin bony stock of the harvested radius. The pliable forearm skin is ideal for the soft tissue defects. We believe that the RFOFF with bone has a definite role in the reconstruction of select head and neck defects.

Osseous reconstruction using a membrane barrier following marginal mandibulectomy: an animal pilot study

BACKGROUND

Invasive and malignant tumors of the oral soft tissues adjacent to the mandible are often treated with partial resection of the osseous structure adjacent to the lesion (marginal mandibulectomy). Autogenous bone graft and composite bone grafts are being used to fill the osseous defects with various degrees of success. The aim of the present study was to explore the utilization of membrane barriers and the principle of guided bone regeneration to negotiate these defects.

METHODS

Following the removal of P1, P2, and P3, experimental bilateral marginal mandibulectomy defects were created in 4 adult dogs. The bone segments (measuring 25 mm x 15 mm) were then removed. Each side was then randomly selected for either experimental (titanium-reinforced expanded polytetrafluoroethylene membrane, [ePTFE-TR]) or control (repositioning flaps) treatment. Postoperatively, the animals were put on soft diet, antibiotics, and analgesics. Sutures were removed under light sedation after 4 weeks, and the area was left to heal and mature for 4 to 6 months (mean 5.3 months). The animals were then sacrificed, and block sections of the mandible were obtained for macroscopic and histological evaluation.

RESULTS

The size of the residual defect (the vertical distance between the most apical depression in the ridge and the horizontal line connecting the free gingival margins of the proximal teeth) in the experimental sites (6.10 +/- 1.00 mm) was much smaller compared to the controls (10.65 +/- 0.82 mm), which was statistically significant (P = 0.0127). Histomorphometric measurements of new bone formation (NBF) revealed a similar pattern: for the experimental sites, NBF was 8.08 +/- 0.85 mm compared to 4.99 +/- 0.61 mm in the controls. These differences were also statistically significant (P = 0.0257).

CONCLUSIONS

A regenerative approach to large mandibular osseous defects has been described. If this new treatment modality is further substantiated in other independent studies, it might prove a useful tool in restoring the lost osseous structure associated with marginal mandibulectomy procedures.

Surgical management of head and neck cancer

Head and neck cancer surgery continues to evolve through the years and undergo improvement and refinement. In this article, the current state of head and neck cancer surgery is summarized in a site-by-site basis. The most important developments include organ-sparing surgery and microvascular free-tissue transfer for reconstruction.