Mandible Reconstruction

Mandibular reconstruction after tumor resection is performed to replace any excised section of mandible with vascularized bone. Soft tissue defects can be filled with skin and subcutaneous tissue based on perforators from the vascular pedicle accompanying the bone graft.  Vascularized bone reconstruction promotes primary healing and increased resistence to infection and resistance to adjuvant radiation therapy necrosis.  It also lends itself to osseointegrated implant dental restoration. Often, patients can begin early range of motion exercises and minimize stiffness in the temperomandibular joint.

Options for vascularized bone microvascular reconstruction most commonly include:

• Circumflex iliac artery osteocutaneous flap

• Radial forearm osteocutaneous flap

• Serratus with rib flap

• Scapular bone osteocutaneous flap

• Fibula osteocutaneous flap

The fibula is an ideal bone for mandibular reconstruction and most commonly used.  In cases where the fibula is not available or only a small piece of bone is required, other options are considered.

Free Fibula Mandible Reconstruction

The fibula is a slender long bone of the lower lateral leg (click here for a body map).  It begins just below the level of the knee joint and descends to the lateral malleolus of the ankle, where it helps provide stability to the ankle joint.  the distal aspect of the bone is left behind to maintain ankle stability.  The very proximal fibula is likewise not removed in order to avoid injury to the peroneal nerve which courses over the neck of the fibula. 

The peroneal artery and its venae course the inner aspect of the fibula bone in the deep posterior compartment.  The artery provides vessels nourishing the bone and supporting its blood flow.  Muscle attachments to the fibula are many and include the extensor digitorum longus, extensor hallucis longus, peroneus longus and brevis, peroneus tertius, tibialis posterior, flexor hallucis longus and soleus.  In practice, the muscles are repaired to maintain length after bone harvest and do not usually cause any significant donor muscular disturbance.

The mandible is a horseshoe shaped bone anatomically divided into a body, angle and ramus.  The ramus is vertically placed and carries the condylar process and the coronoid process.  The condylar process abuts the mandibular fossa and forms the temporomandibular joint.  The coronoid process is insertion point for the temporalis muscle, one of the muscles of mastication.  The vertical ramus is inferiorly connected to the body at the angle.  The body is transverse, connected to the mandibular body on the other side by the mentum.  In reconstruction of the mandible, multiple osteotomies of the fibula are often necessary to reconstruct the ramus, body and mentum.

Preoperative Evaluation

Any head and neck tumor requires a thorough preoperative evaluation by a head and neck surgeon for staging and tumor treatment recommendations.  If surgical resection is recommended and reconstruction is required, a thorough history and physical examination is essential before developing the most appropriate treatment regimen.  The following are of critical interest to the microsurgeon

• Tumor histology and staging with physical examination of the tumor or tumor defect

• Skeletal examination – both upper and lower extremities and mandible are asessed.

• Vascular assessment - the presence of injury – surgical, radiation or otherwise - to the vascular system of the head and neck or donor area will often dictate the choice of flap and design.

• Neurological evaluation – lack of function to facial muscles with injury to the facial nerves, lingual and swallowing function are assessed.  Any history of stroke or transient ischemic attacks would point to possible carotid system disease. 

The physician may require angiography of the carotid and/or lower extremities to complete the vascular assessment.  If not already performed, a CT scan or panorex of the mandible is obtained.

Clinical Example and Surgical Technique

The majority of the length of of the fibula is removed, sparing the proximal end and the distal component involved in ankle stability.  The bone is isolated on the peroneal artery and the accompanying veins, sometimes with a skin paddle, depending on the need for soft tissue reconstruction.  The fibula is pictured below on the right after an osteotomy (bone cut) distally and proximally.

The illustration below depicts the portion of the mandible, in this case, that was removed in order to resect the tumor.  The piece extends from the angle on the right to the body on the left.

The fibula is marked preoperatively on the lower leg.  The skin paddle was used to reconstruct a soft tissue defect inside the mouth.  The peroneal nerve course is marked on the skin to avoid injury. 

The fibula has been dissected free and is still attached on its artery and vein, seen with the blue background.

After the bone is removed, appropriate osteotomies are made to shape the bone into the mandibular defect.  In this case, a single osteotomy was required as illustrated below.

The fibula is seen below after fixation of the osteotomy with a reconstruction plate.  The skin paddle faces the other way against the blue towel background.   

The plate is fixed to the native mandible.  The blood vessels to the bone are then microsurgically repaired to the facial vessels.  

The panorex x-ray of the patient obtained approximately six months after surgery shows that the osteotomy sites are well healed and there is good bony alignment.