Mandibular Reconstruction

Views:
 
Category: Education
     
 

Presentation Description

No description available.

Comments

Presentation Transcript

Mandibular Reconstruction:

Mandibular Reconstruction Special Considerations in Condyle and TMJ Reconstruction.

Outline:

Outline History Anatomy Classification Reconstructive Techniques Available TMJ reconstruction XRT and TMJ reconstruction

Importance of the Mandible:

Importance of the Mandible Airway Stability Speech Deglutition Mastication The mandible must be able to withstand a significant amount of force during mastication Maximal Molar Occlussal Forces of 4346N Shape and Contour of the Lower Face

Avoiding the “Andy Gump Deformity”:

Avoiding the “Andy Gump Deformity”

History:

History Before advanced surgical techniques and improved hardware, disappointing results Vascularized Bone Grafts disappointing as failures reached 50% Advances in free tissue transfer including osteocutaneous free flaps have revolutionized mandibular reconstruction Panje and colleagues introduced successful reconstruction in 1976 with free groin transfer opening the door to further advances Hardware initially composed of Vitallium (alloy containing cobalt, chromium, and molybdenum Initial combination of well- vascularized soft tissue reconstruction with recon plates significantly improved short-term results

History (continued):

History (continued) Long term results of soft tissue reconstruction with recon plates disappointing owing to plate extrusion, plate fracture, and screw loosening

Mandible Anatomy (continued):

Mandible Anatomy (continued) Strongest Facial Bone U-shaped with horizontal section (body) containing the alveolar process with 2 vertical segments (rami) which through the temporomandibular joints articulate with the skull Dense cortical structure with small core of spongiosa containing nerves, blood vessels, and lymphatic vessels

Mandible Anatomy:

Mandible Anatomy

Mandible Anatomy (continued):

Mandible Anatomy (continued) Alveolar Process contains dental sockets to support teeth Changes to alveolar process occur throughout adult life, especially after dental extractions Mental foramen found between inferior border and upper edge of alveolar process at the level of the second premolar tooth

Mandible Rami:

Mandible Rami Rami composed of broad, thin plates of dense bone Each joins with body to form angle of mandible Anteriorly ends in the coronoid and condylar processes Inferior Alveolar Nerve passes through the Mandibular Foramen into the Alveolar Canal

Mandibular Movement:

Mandibular Movement Dependent primarily on 2 groups of muscles Depressor-Retractor Group Geniohyoid Digastric Elevator Group Masseter Medial Pterygoid Temporalis

Masseteric-Pterygoid Sling:

Masseteric-Pterygoid Sling Medial Pterygoid inserts on inner surface at mandible angle while Masseter inserts on outer surface Angulation of attachment at the angle more favorable for the medial pterygoid Medial pterygoid overpowers masseter in segmental defects causing typical displacement patterns inward

Other Muscles Involved:

Other Muscles Involved Lateral Pterygoid and Mylohyoid have minor influences on the movement of the mandible. Lateral Pterygoid - attaches to the neck and pulls anteriorly and medially.

Indications for Resection:

Indications for Resection Ablative Surgery for Benign or Malignant Neoplastic tumors. Often associated with soft-tissue defect. Trauma. Osteoradionecrosis. Bisphosphonate-induced osteonecrosis. Osteomyelitis.

Classifications for Mandible Defects:

Classifications for Mandible Defects Various Classification Schemes HCL (Boyd and colleagues classification) H defects are lateral defects of any length up to midline including condyle L defects lateral excluding the condyle C defects involve central segment containing 4 incisors and 2 canines 3 lower case letters describe soft tissue component o – no skin or mucosa s – skin m – mucosa sm – skin and mucosa

Boyd and Colleagues Classification:

Boyd and Colleagues Classification

Classifications for Mandible Defects:

Classifications for Mandible Defects Urken et al Classification Based on functional considerations caused by detachment of different muscle groups and difficulties with cosmetic restoration C – condyle R – ramus B – body S – total symphysis SH – hemisymphysis

Urken et al Classification:

Urken et al Classification

Goals of Mandibular Reconstruction:

Goals of Mandibular Reconstruction Accurate Classification of defect and understanding of functional deficits Restore Form and Function Restore Bony Contour of native mandible Restoration of Mastication Greater then loss of tongue volume, greater negative impact on patient’s prognosis for recovery of oral function Deglutition Articulation Maintenance of adequate airway

Current Mandibular Reconstruction Techniques:

Current Mandibular Reconstruction Techniques Alloplastic implants Vascularized free tissue transfer Adjuvants to vascularized osseous free tissue transfer

Alloplastic implants:

Alloplastic implants Most commonly used are bone plates and screws Indicated in patients with poor performance status or where soft-tissue defects of the oral cavity/oropharynx are more extensive than bony mandibular defect. Innovation in self-drilling, self-tapping screws and locking miniplates assist in microvascular reconstruction

Titanium Hollow Screw Osseointegrating Reconstruction Plate (THORP) System:

Titanium Hollow Screw Osseointegrating Reconstruction Plate (THORP) System First reconstruction plate with mechanism for osseointegration at the bone-to-screw interface Locking mechanism at screw-to-plate interface Found to be superior to solid screw steel and titanium plates Recent studies comparing THORP to vascularized bone grafts show significant delayed complications of hardware extrusion

Vascularized Free Tissue Transfer:

Vascularized Free Tissue Transfer Fibular Free Flap Scapular Free Flap Iliac Crest Free Flap Radial Forearm Free Flap Double Flap Reconstruction

Fibular Free Flap:

Fibular Free Flap Workhorse of mandibular reconstruction Used to reconstruct bony defects as long as 30cm in length Vascular pedicle may be 6-10 cm in length Allows placement of osseointegrated dental implants Only donor site that allows reconstruction of total mandibular defects

Fibular Free Flap (continued):

Fibular Free Flap (continued) Based on the Peroneal Artery and Vein Harvested with the Flexor Hallucis Longus Muscle Skin Island can be used both intraoral and Externally Can harvest up to 27cm of bone Receives both segmental and intraosseous blood supplies allowing for multiple osteotomies Position allows for simultaneous dissection Small Defects (<5cm) can be primarily closed

Limitations of Fibular Free Flap:

Limitations of Fibular Free Flap Limited in amount of soft tissue that can be transferred Skin island thought to be “unreliable” Does not recreate alveolar height of native dentate mandible Donor site generally minimal IF 7-8cm of bone at ankle and 3-4 cm of bone at knee are preserved Most patients return to full ambulation in 2 months

Pre-operative Evaluation:

Pre-operative Evaluation Evaluation of lower extremity vasculature recommended to assess disease precluding transfer MR angiography recommended and has replaced conventional angiography

Fibular Free Flap (continued):

Fibular Free Flap (continued)

“Avoiding Secondary Skin Graft Donor Site Morbidity in the Fibula Free Flap Harvest” – Kim et al.:

“Avoiding Secondary Skin Graft Donor Site Morbidity in the Fibula Free Flap Harvest” – Kim et al. Cohort Study involving 30 patients Donor site closure remains somewhat controversial with most advocating split-thickness skin graft from secondary donor site STSG site often adds to pain and poses potential for addition morbidity Purposes of study to examine donor site morbidity in patients undergoing fibula free flap reconstruction where skin graft taken from cutaneous paddle of the fibula

Methods:

Methods September 1, 2006 to March 30, 2007 30 patients included in study from 2 institutions 15 men and 15 women with mean age of 58 (range 19-88 years) All underwent fibula free flap harvest with STSG (thickness 0.04cm)

Outcomes Measured:

Outcomes Measured Flap Failure Hardware complications Intraoral complications Need for additional surgery

Results:

Results 14 donor sites from the right leg 16 donor sites from the left leg Average STSG thickness 0.04 cm with area of 16x6cm 26 patients with viable skin grafts at follow up (87%) 4 (13%) with partial loss (range of 15-50% of graft) 0 were completely lost

Results (continued):

Results (continued) Primary Tumors composed of 20 squamous cell carcinoma (67%) 6 mucoepidermoid carincoma (20%) 2 osteosarcoma (7%) 1 mandibular osteoradionecrosis (3%) 1 osteomyelitis (3%)

Tumor Location:

Tumor Location 6 major sites of soft tissue defect Floor of mouth (12 tumors, 40%) Mandibular alveolar ridge (8 tumors, 27%) Base of tongue (3 tumors, 10%) Parotid (3 tumors, 10%) Oral tongue (2 tumors, 7%) Pharynx (2 tumors, 7%)

Results (continue):

Results (continue) Average flap ischemia time 2 hours, 38 minutes (range of 1 hour 45 minutes to 4 hours); did not contribute significantly to outcome measures One skin paddle necrosis requiring surgical debridement (patient seropositive for HIV with post-operative Streptococcus infection 2 patients with orocutaneous fistulas managed conservatively with dressing changes 1 patient with adhesion formation between base of tongue and tonsil defect requiring adhesion lysis with placement of STSG

Intra-operative and Post-operative .pictures:

Intra-operative and Post-operative . pictures

Discussion:

Discussion Post-operative minor fistula rate was 7% No major fistulas requiring flap or other surgical interventions 17 (57%) of patients in study required post-operative radiation therapy (1 of 2 patients in study with fistula formation) Complication of procedure involved patient with opposing defects, developing post-operative adhesions requiring additional surgery – authors recommend that in defects involving opposing surfaces, epithelialized tissue should be used

Postoperative photograph shows adhesion from the right side of the tongue to the right side of the pharynx.:

Postoperative photograph shows adhesion from the right side of the tongue to the right side of the pharynx .

Scapula Free Flap:

Scapula Free Flap Flap based on Circumflex Scapular Artery and Vein Vessels of good length and diameter Provides up to 14 cm of bone but of poor quality generally Large, well vascularized skin island with moderate bulk Can be osteotomized safely Cannot be performed simultaneously with ablative procedure

Scapular Free Flap:

Scapular Free Flap Good choice of through and through defects involving facial skin, bone, and mucosa Many recommend it’s use in recurrent parotid malignancies requiring cheek skin and ascending ramus resection Can accept Osseo integrated dental implants Especially useful in setting of salvage surgery after Chemo/XRT failure due to ability to include latissmus dorsi muscle used to cover major vasculature in neck Preferred by some for geriatric patient due to ability to ambulate early after surgical resection

Limitations of Scapular Free Flap:

Limitations of Scapular Free Flap Decreased range of motion of shoulder Difficult for 2 team approach Limited in amount of bone harvestable

Scapular Free Flap:

Scapular Free Flap

Iliac Crest Osseocutaneous Free Flap:

Iliac Crest Osseocutaneous Free Flap One time, workhorse of mandible reconstruction Blood supply based on Deep Circumflex Iliac Artery Vessels are generally short and of small diameter Can harvest large quantity of bicortical bone

Iliac Crest Osteocutaneous Free Flap (continued):

Iliac Crest Osteocutaneous Free Flap (continued) Supplies bone with height comparable to native dentate mandible Contoured to fit most segmental mandibular defects Can harvest internal oblique muscle by including ascending branch of DCIA

Iliac Crest Free Flap:

Iliac Crest Free Flap

Disadvantages of Iliac Crest:

Disadvantages of Iliac Crest Bone lacks segmental perforators Skin Island Unreliable and often provides too much bulk Donor Site Morbidity Numbness to Anterior Hip Region Complications include Hernia of the internal oblique muscle

Long-term follow-up for Free-flap Mandible Reconstruction:

Long-term follow-up for Free-flap Mandible Reconstruction Hidalgo et al completed 10-year follow up study Found acceptable aesthetic outcomes in 90% of patients 70% of patients were eating regular diet while rest of patients in study remained on soft diet More than 90% of bone height was preserved Study often cited most for efficacy of free-flap reconstruction of mandible defects

Adjuncts to Vascularized Osseous Free Tissue Transfer:

Adjuncts to Vascularized Osseous Free Tissue Transfer Temporary Intraoperative External Fixation Aids in maintaining the preoperative three-dimensional relationships Commonly done with bridging reconstruction bar or use of arch bars and intermaxillary fixation Periosteal Free Flaps Fascioperiosteal radial forearm free flap Used to enhance survival of iliac crest corticocancellous autograft Kelley et al (2003) found osteogenic capacity of periosteal tissues Osseointegrated Dental Implants Require bone height of approximately 6 to 7mm Found to work identically to implants on native bone Must delay placement for at least 6 months if receiving postoperative radiation

Nonvascularized Bone Grafts:

Nonvascularized Bone Grafts Used to reconstruct partial mandibular defects from small segmental resections Not used when soft tissue defects are present Advocated only in uses of small, partial or segmental mandibular defects Often cancellous bone chips Autogenous bone chips often taken from iliac crest No mucosal or soft-tissue defects Should never be used in patient’s undergoing radiation therapy as results have been poor with many complications

Posterior Mandible Defects:

Posterior Mandible Defects Reconstruction techniques involving the condyle are controversial Oral competence, tongue and laryngeal mobility not significantly affected Reconstruction of TMJ and condyle is usually disappointing

“A Prospective Analysis of Bony versus Soft-Tissue Reconstruction for Posterior Mandibular Defects” Hanasona et al. 2010:

“A Prospective Analysis of Bony versus Soft-Tissue Reconstruction for Posterior Mandibular Defects” Hanasona et al. 2010 Prospective Trial of 74 patients (45 men and 29 women) undergoing microvascular free flap reconstruction at UT Houston Compared outcomes between vascularized bone flap and soft tissue free flap reconstruction Posterior mandible defect defined as one that includes at least the condyle and ramus up to angle

Data Collected::

Data Collected: Age Tobacco Use Medical comorbities Dentition History of Preop or Postop Radiation and chemotherapy Details of defect and reconstruction Perioperative complications Post-operative diet Post-operative mouth opening ASA class Kaplan-Feinstein classification Mouth Opening Crossbite

Results:

Results

Results (continued):

Results (continued) Time to oral intake, postoperative diet and mouth opening similar between 2 groups Degree of cross-bite sole functional outcome difference (0 to 6mm in vascularized bone flap group and 0 to 16mm in soft-tissue free flap) Advanced age, higher ASA class, and Kaplan-Feinstein classification biased toward soft-tissue free flap reconstruction Oncologic prognosis did not affect reconstructive technique Presence of natural or prosthetic teeth influences ability to have regular mechanical vs. soft or pureed diet

Decision Algorithm:

Decision Algorithm

What to do with the condyle?:

What to do with the condyle? Disarticulation resection results in complex deformity that can affect facial appearance and oral function Options are limited Reconstruction plates with attached metallic condylar prostheses Autogenous rib grafting Cadaveric mandibles Vascularized Tissue Transfer

The Temporomandibular Joint:

The Temporomandibular Joint

Condylar Prostheses:

Condylar Prostheses Alloplastic materials first reported by Gordon in 1955 Rationale was to use implant to maintain functional mandibular ramus height, avoid malocclusion, and prevent hypomobility Condylectomy without reconstruction would result in facial deformity, pain, and limitation of movement

“Condylar Prostheses in Head and Neck Cancer Reconstruction” Patel A, 2001:

“ Condylar Prostheses in Head and Neck Cancer Reconstruction” Patel A, 2001 Case Series and Literature Review 4 patients from September 1989 to April 1995 Underwent condylar reconstruction with metallic condylar prostheses after hemimandibulectomy Three patients required reconstruction for retromolar trigone squamous cell carcinoma 1 received pre-operative radiation therapy 2 received post-operative radiation therapy One patient required reconstruction for Ewing’s sarcoma

Results:

Results Post-operative follow-up with special attention toward complications Mean follow-up of 23.3 months (5-37 months) Cross-bite deformity and malocclusion (n=1) Infection (n=2) Transient Facial Nerve Paralysis (n=1)

Migration of Prosthesis into Epitympanum:

Migration of Prosthesis into Epitympanum An axial computed tomogram of the temporal bones shows extension of a prosthesis into the epitympanum, abutting the ossicular chain. Also, bony destruction exists medially from the epitympanum to the cochlea. 1 patient with migration of prosthesis into epitympanum Caused otorrhea, Profound SNHL due to bony destruction of cochlea, and transient facial nerve paralysis

Radiation-Related Complications:

Radiation-Related Complications Patient with exposed bar 5 months after placement. Exposure or Extrusion of prosthesis in the 3 patients with radiation exposure

Conclusions of Case Series:

Conclusions of Case Series Metallic condylar prosthesis in settings of tumor resection and reconstruction involve significant risks and potential complications Do not offer satisfactory results Authors suggest vascularized bone grafting when possible

“Free-Flap Mandibular Reconstruction: A 10-Year Follow-Up Study” Hidalgo et al, 2001:

“Free-Flap Mandibular Reconstruction: A 10-Year Follow-Up Study” Hidalgo et al, 2001 Single Surgeon’s experience retrospectively reviewed 82 patients from January 1987 to December 1990 Mean length of follow-up of 11 years Mean patient age of 48 years Examined many aspects including aesthetics, return to diet

Condyles:

Condyles Condyle can be resected and fixed to the end of the free-flap bone graft These grafts can last for over a decade 2 patients where nonvascularized condyle failed Advocates the use of nonvascularized graft when specimen transection is planned at the midramus or higher Superior alternative to no reconstruction, shaping the end of the graft, or using a prosthetic condyle

Radiation Results:

Radiation Results 12 of 20 patients received full radiation therapy following mandible resection and primary reconstruction Shown to not delay healing of osteotomies or to compromise bone graft viability Osseointegrated dental implants were not placed in these patients

Materials Available:

Materials Available Metallic Implants Christensen implant Titanium-coated Hollow-screw Reconstruction Plate (THORP) Silicone Rubber (Silastic) Proplast Polytef (Teflon) Autogenous Materials Temporalis muscle/fascia flap Osteochondral rib grafts Vascularized bone grafts

Christensen prosthesis:

Christensen prosthesis In use for more than 25 years Comprises metal fossa and metal condyle with articulating dome of polymethylmethacrylate Has been successful in severe TMJ disorders Polymethylmethacrylate can cause fibrosis, neo-ossification or heterotrophic bone formation Can create patient-specific TMJ prosthesis

Christensen implant:

Christensen implant Courtesy TMJI, INC. accessed on http://www.tmj.com/products/tmj_total_custom.php on 8/29/2010

Titanium-Associated Hollow-Screw Reconstruction Plate:

Titanium-Associated Hollow-Screw Reconstruction Plate Raveh et al reported successful reconstruction in 2 patients Major advantages: Stable anchorage of carrier plate to mandible by hollow screws 3-dimensional adaptability of condylar prosthesis after fixation to mandible Allows condyle to articulate with glenoid fossa reproducing normal rotational and translational movement Advent of osteointegrating screws that lock to plate has reduced risk of loosening hardware

THORP:

THORP

THORP (continued):

THORP (continued) Kim and Donoff used reconstruction plates to reconstruct mandibular condyle and ramus in 13 patients 1 patient required revision or plate removal secondary to infection Majority of plate losses secondary to patients undergoing irradation which is often necessary in advanced stage cancers requiring mandibulectomy

“Erosion and heterotopic bone formation after alloplastic temporomandibular joint reconstruction” Lindqvist et al, J Oral Maxillofac Surg 1992:

“ Erosion and heterotopic bone formation after alloplastic temporomandibular joint reconstruction” Lindqvist et al, J Oral Maxillofac Surg 1992 23 TMJ arthroplasties using metallic condylar prostheses, 9 for malignant tumors Average follow-up of 25 months Clinical and Radiographic follow-up study Reconstruction plate including condyle (AO/ASIF reconstruction plate, Stratec Medical) Radiographic evaluation included Panorex and Towne view, also used other modalities when clinically relevant

Malignant Tumors:

Malignant Tumors 9 patients required reconstruction secondary to malignant tumors Three plates required removal secondary to infection (two cases) or necrosis of the pectoral flap (one case) Plate fractured in 1 patient requiring exchange Three patients died during follow-up (2 patients had functional alloplastic joint) Condyle displaced in 4 cases Two cases of bony erosion into the skull base Heterotrophic new bone formation in four joints

Malignant Tumors:

Malignant Tumors

Discussion:

Discussion Tumor patients can benefit from condylar prosthesis for reconstruction Special anatomic and functional conditions in the region of the TMJ articulation indicate using autogenous materials whenever possible

Complications of Condylar Reconstruction:

Complications of Condylar Reconstruction Temporary or Permanent Facial Nerve Weakness Middle Ear infections Temporary or Permanent hearing loss Tinnitus Disequilibrium Malocclusion Infection Extrusion or exposure of the prosthesis Adhesions or ankylosis within the joint space Heterotrophic bone formation Bony erosion of the skull base Foreign body reaction Rejection of the implant

Radiation Therapy:

Radiation Therapy Plate exposure is most common cause of reconstructive failure Increased incidence in patients requiring extensive soft tissue resection or radiation therapy Some authors have expressed concern with titanium plates as they potentionally can cause hot spots contributing to overlying skin breakdown

Implants:

Implants Proplast, polytef (Teflon), and Silastic known to cause severe foreign body giant cell reaction Can cause soft tissue and bony destruction Migration of microparticulate debris to other areas Implants no longer indicated in condylar reconstruction

Autogenous Materials:

Autogenous Materials Free bone grafts, especially the osteochondral rib graft, often susceptible to unpredictable resorption, and often insufficient for reconstruction of ramus and body Vascularized bone grafts effective Resistant to infection and extrusion Can survive in poor recipient bed from prior irradiation Fibular free flap and iliac crest have best functional and aesthetic results Can restore bony and soft tissue defects in one procedure

Fibular Free Flap and Reconstruction of Condyle:

Fibular Free Flap and Reconstruction of Condyle 3 techniques available Addition of condylar prosthesis to the flap Addition of resected condyle to the flap Placement of distal portion of flap directly into glenoid fossa Condylar prosthesis has many complications involved Addition of native condyle often not possible

Fibula flap reconstruction of the condyle in disarticulation resections of the mandible: A case report and review of the technique” Engroff, OOOOE, December 2005:

Fibula flap reconstruction of the condyle in disarticulation resections of the mandible: A case report and review of the technique” Engroff , OOOOE, December 2005 Case report of 33 y/o M with left odontogenic keratocyst Fibula free flap used to reconstruct condyle Distal end of the fibula free flap was rounded allowing it to seat passively against TMJ disc in glenoid fossa Masseter muscle sutured to angle of reconstruction plate to actively seat the “neocondyle” into the fossa

Application of fibula free flap to reconstruct the left mandible as seen on panorex 4 weeks postoperatively:

Application of fibula free flap to reconstruct the left mandible as seen on panorex 4 weeks postoperatively

Condyle Reconstruction :

Condyle Reconstruction Hidalgo shown that condyle as free graft to flap is a viable alternative Fibula well-suited for reconstruction of condyle Tubular in shape and densely cortical Narrow shape allows fit through the soft tissue tunnel avoiding dissection around the facial nerve Several studies have shown success in this technique Guyot et al reported 11 patients followed over 6 years, oral function was preserved with no cases of ankylosis

Conclusions:

Conclusions Mandibular Reconstruction poses a specific challenge in both functionality and aesthetics There are many options available, each with its own risks and benefits The fibula free flap has become the workhorse of mandible reconstruction The condyle and TMJ remain surgical challenges in tumor reconstruction Free tissue transfer has been proven to be the most beneficial

Conclusions (continued):

Conclusions (continued) Radiation, both pre-operatively and post-operatively, increases risks involved with mandibular reconstruction Limited evidence in radiation and TMJ reconstruction Metallic prostheses have many complications when involved in tumor reconstruction Further work remains in developing a standard reconstruction of the condyle and TMJ