Mandibular Reconstruction: Graft? Flap?

While this is an old topic, the article¹ sheds new light on the interpretation of invasiveness.

Summary of the article

The decision of whether to use vascularized versus nonvascularized reconstructions for mandibular defects is a complex one, relying on a multitude of considerations unique to a patient’s clinical presentation, anatomy, systemic health, and overall treatment goals. There is still significant debate on this topic within the field of oral and maxillofacial surgery.

Key factors that should be considered when making this reconstructive decision include:

• The type and size of the mandibular defect.
• The underlying pathology (benign vs. malignant).
• Soft tissue requirements and the ability to achieve primary mucosal closure.
• The need for or history of radiation exposure.
• Comorbid disease burden.
• The anticipated timescale of reconstruction.
• The predictability and reliability of the reconstruction method.

Nonvascularized Bone Grafts:

• These grafts have a long history and remain a cornerstone of contemporary mandibular reconstruction practice.
• They are generally considered best suited for small subsegmental mandibular defects, specifically where the inferior border is preserved (marginal mandibulectomy defects).
• Success is more likely when there is adequate native soft tissue available to allow for primary mucosal closure of the defect.
• They are most often associated with benign pathology, as treatment for benign lesions frequently allows for soft tissue preservation and primary closure.
• For segmental defects, the highest probability of success with nonvascularized grafts is in scenarios where primary closure of oral mucosal tissues is possible and a delayed second-staged grafting procedure is performed via a sterile (transcervical) approach after adequate mucosal healing.
• However, even with refined techniques and appropriate case selection, defect length can still remain a risk factor for failure, although modern studies show success even in traditionally considered "long span" defects (6-10 cm) under specific conditions.
• Crucially, a prior history of head and neck radiation treatment or an expected need for adjuvant radiation therapy should strongly select against nonvascularized reconstructions. This is because nonvascularized grafts depend on neovascularization and capillary ingrowth from the surrounding tissue bed to remain viable. Radiated tissue beds have reduced vascularity, increased scarring/fibrosis, and compromised healing, which greatly diminishes their ability to support nonvascularized grafts, leading to a higher risk of resorption, necrosis, and failure.
• Nonvascularized reconstructions generally require significantly extended timeframes to achieve functional reconstruction and the insertion of a final prosthesis. As detailed in the source’s workflow table (Table 1/Fig 8), even the "accelerated" pathway for nonvascularized grafts can take around 11 months from index surgery to final prosthesis insertion. The "non-accelerated" pathway can extend to 18 months or more. Patients may feel "incomplete" for approximately a year even in the accelerated pathway.
• While sometimes considered "less invasive" in terms of the initial surgery, nonvascularized grafts can be "highly invasive to a patient’s time and quality of life" due to the extended treatment timeframes and potential need for multiple procedures.

Vascularized Bone Grafts (Free Flaps):

• With increased training in microvascular surgery, the availability and reliance on free tissue transfer for complex mandibular reconstruction have significantly increased.
• They are often indicated for segmental mandibulectomy defects, particularly in cases of primary intraosseous malignant pathology, epithelial carcinomas invading bone, or when marginal mandibulectomy is not feasible for benign disease extending to the inferior border.
• They are considered more suitable for malignant disease, largely because such treatment frequently necessitates adjuvant radiation therapy.
• They are necessary when the anticipated defect does not allow for passive primary closure of the soft tissues without distortion or contracture, as they can augment the surrounding soft tissue envelope simultaneously with bone reconstruction.
• Vascularized reconstructions have become the standard of care for reconstructing compromised and radiated tissue beds. This is because their survival does not rely on the diminished vascularity of the surrounding radiated tissue.
• Vascularized reconstructions will generally enable significantly shortened timescales for the completion of functional reconstructions compared to nonvascularized grafts. As shown in Table 1/Fig 8, the "non-accelerated" pathway for vascularized grafts can result in final prosthesis insertion around 4 months from index surgery, while the "jaw-in-a-day" accelerated approach can achieve this in just 3 months. Patients feel "complete" (with a provisional prosthesis) much sooner, sometimes at 3 months or even at the index surgery.
• They offer greater predictability, reliability, and speed in achieving functional rehabilitation, even in challenging scenarios.

The Time-Sensitive Nature of Adjuvant Radiation Therapy:

• This is a critical factor when selecting reconstructive options, particularly in cases of malignant disease.
• To maximize therapeutic benefit in an adjuvant setting, radiation therapy must generally be initiated within 5 to 6 weeks following primary tumor resection.
• If radiation therapy is initiated outside of this optimal 5-6 week window, it becomes less effective for oncologic control, yet the negative side effect profile remains unchanged.
• Therefore, any reconstructive or surgical complications that cause delays in the timely initiation of adjuvant radiation therapy result in reduced therapeutic benefit while still exposing the patient to detrimental side effects.
• Surgeons must choose reconstructive options that are not only reliable but also allow for adequate healing by the time adjuvant therapy needs to start so that treatment is not delayed or, in severe cases, omitted.
• Vascularized grafts offer faster, more predictable healing timelines. This makes them inherently better suited to avoid delays in initiating time-sensitive adjuvant radiation therapy compared to the protracted timelines associated with non-vascularized grafts.

Other Considerations:

• Soft tissue needs are paramount; if the expected defect requires significant soft tissue replacement beyond primary closure capabilities, vascularized free tissue transfer is almost always necessary, regardless of whether the pathology is benign or malignant.
• While non-vascularized grafts can have high success rates in specific, favorable scenarios (short span, lateral defects, non-radiated, primary closure, delayed grafting), straying from these specific parameters leads to greater risk of complications and suboptimal outcomes. Vascularized grafts maintain higher predictability and reliability across a wider range of defect types and patient conditions.
• In certain extreme circumstances, particularly with significant patient comorbidities and prior extensive treatment like chemoradiation, a patient may not be a candidate for either vascularized or nonvascularized bone reconstruction. In these cases, simply placing a reconstruction plate with soft tissue coverage (like a regional flap) might be the "least bad option" to achieve oncologic clearance and maintain some structural support, though it is understood this often leads to future complications like hardware exposure.

In conclusion, while non-vascularized grafts retain a role in selected, favorable cases characterized by small, non-radiated defects with ample soft tissue allowing for primary closure, their limitations in complex defects, compromised tissue beds (especially from radiation), and the significantly longer timeframe for functional recovery make them less ideal in many modern reconstructive scenarios. The increased predictability, reliability, versatility, and significantly shorter time to functional recovery offered by vascularized free flaps make them the preferred choice for reconstructing radiated fields, complex defects requiring significant soft tissue, or when adjuvant radiation is anticipated, critically enabling timely oncologic treatment within the optimal window for maximum benefit.

More about invasiveness

Surgeons commonly discuss procedural invasiveness—surgical incisions, dissection extent, post-operative pain, complication risks, hospital stay length, etc.—with patients. Yet we rarely address how treatment invades their lives and time.

The authors argue that most surgeons view vascularized free flaps as more invasive than traditional nonvascularized grafts when selecting donor sites—based on historical definitions of ‘invasiveness.’ However, this perspective focuses solely on the initial procedure, overlooking both the flap’s reliability in providing immediate, functional bone volume for implantation and the multi-stage requirements of traditional reconstruction.

The authors give us a summary of general timing of workflow for reconstructive stages compared between vascularized (ie, fibular free flap) and non-vascularized bone grafts (ie, anterior iliac crest bone graft tissue engineering) for a routine segmental mandibular defect, which I think is of great reference value for our daily work：

Table 1: General Timing of Workflow for Reconstructive Stages Compared Between Vascularized and Non-Vascularized Bone Grafts for a Routine Segmental Mandibular Defect

Reconstructive Stages	Vascularized Bone Graft	Nonvascularized Bone Graft
Tumor Resection	Index Surgery	Index Surgery
Defect reconstruction	Simultaneous	Delayed 6-8 wk after index surgery (accelerated workflow) -or- Delayed 3-6 mo after index surgery (non-accelerated)
Implant placement	Simultaneous	Staged 6 mo after defect reconstruction (accelerated) -or- Staged 6-9 mo after defect reconstruction (non-accelerated)
Implant uncovering	Simultaneous ("jaw-in-a-day" application) -or- Staged 3 mo after index surgery (non-accelerated workflow)	Staged 4 mo after implant placement (accelerated) -or- Staged 6 mo after implant placement (non-accelerated)
Insertion provisional prosthesis	Simultaneous ("jaw-in-a-day" application) -or- Staged 3 mo after index surgery (non-accelerated workflow)	Staged 4 mo after implant placement (accelerated) -or- Staged 6 mo after implant placement (non-accelerated)
Insertion final prosthesis	Staged 3 mo after index procedure ("jaw-in-a-day" application) -or- Staged 1 mo post-insertion of provisional prosthesis (non-accelerated workflow)	Staged 1-3 mo after insertion of provisional prosthesis (accelerated and non-accelerated workflows)
Duration of treatment (index surgery to insertion final prosthesis)	3 mo ("jaw-in-a-day") -or- 4 mo (non-accelerated)	11 mo (accelerated) -or- 18+ months (non-accelerated)

Notes from the Source:

• For vascularized bone grafts, the accelerated workflow is the "jaw-in-a-day" application, where osseous free flap reconstruction, immediate implant placement, immediate implant loading, and provisional prosthesis insertion happen simultaneously with tumor resection.
• For nonvascularized bone grafts, the accelerated workflow involves a minimal delay of 6-8 weeks between tumor resection and bone grafting to achieve oral mucosal seal, followed by secondary bone grafting transcervically. This is the earliest reported time to consider secondary grafting in the literature, though 3 months is often considered more ideal even in an accelerated pathway for longer defects.
• In the accelerated nonvascularized pathway, there is a 6-month consolidation phase for the graft before implant placement.
• For both nonvascularized pathways, there is a minimum 4-month period (accelerated) or 6-month period (non-accelerated) for implant osseointegration before second stage uncovering and provisional prosthesis placement.
• Typically, providers with experience in nonvascularized grafting do not perform immediate loading of implants due to the softness of the graft even after consolidation.
• Patients generally feel "completely" reconstructed when they receive their provisional prosthesis. For vascularized grafts, this is at 3 months (non-accelerated) or index surgery ("jaw-in-a-day"). For nonvascularized grafts, even in the accelerated pathway, this point is reached about a year after the index procedure.

1. Ettinger KS, Arce K, Bunnell AM, Nedrud SM. Mandibular Reconstruction: When to Graft, When to Flap, and When to Say No. Atlas Oral Maxillofac Surg Clin North Am. 2023 Sep;31(2):91-104. doi: 10.1016/j.cxom.2023.03.002. Epub 2023 May 12. PMID: 37500204. ↩