Mandibular Reconstruction: Special Considerations in Condyle and ...

Benjamin Walton, MD Faculty Advisor: Vicente Resto, MD, PhD

The University of Texas Medical Branch at Galveston Department of Otolaryngology

Grand Rounds Presentation August 31, 2010

History

Anatomy

Classification

Reconstructive Techniques Available

TMJ reconstruction

XRT and TMJ reconstruction

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

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

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

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 Flint: Cummings Otolaryngology:

Head & Neck Surgery, 5th ed.

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 Anatomy Flint: Cummings Otolaryngology:

Head & Neck Surgery, 5th ed.

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

Mandible Anatomy Flint: Cummings Otolaryngology:

Head & Neck Surgery, 5th ed.

Dependent primarily on 2 groups of muscles Depressor-Retractor Group

Geniohyoid

Digastric

Elevator Group

Masseter

Medial Pterygoid

Temporalis

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

Lateral Pterygoid and Mylohyoid have minor influences on the movement of the mandible

Lateral Pterygoid- attaches to the neck and pulls anteriorly and medially

Ablative Surgery for Benign or Malignant Neoplastic tumors Often associated with soft-tissue defect

Trauma

Osteoradionecrosis

Bisphosphonate-induced osteonecrosis

Osteomyelitis

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

P. Maurer et al. / British Journal of Oral and Maxillofacial Surgery 48

(2010) 100–104

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 Mehta and Deschler

Mandibular reconstruction in 2004 289

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

Alloplastic implants

Vascularized free tissue transfer

Adjuvants to vascularized osseous free tissue transfer

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

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

Fibular Free Flap

Scapular Free Flap

Iliac Crest Free Flap

Radial Forearm Free Flap

Double Flap Reconstruction

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

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

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

Evaluation of lower extremity vasculature recommended to assess disease precluding transfer

MR angiography recommended and has replaced conventional angiography

Fibular Free Flap (continued) M. Bak et al. / Oral Oncology 46

(2010) 71–76

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

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)

Flap Failure

Hardware complications

Intraoral complications

Need for additional surgery

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

Primary Tumors composed of 20 squamous cell carcinoma (67%)

6 mucoepidermoid carincoma (20%)

2 osteosarcoma (7%)

1 mandibular osteoradionecrosis (3%)

1 osteomyelitis (3%)

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%)

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

Inraoperative and Post-operative pictures

Kim et al, Arch Otolaryngol Head Neck Surg/Vol 134 (No12), Dec 2008

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. Kim et al, Arch Otolaryngol Head

Neck Surg/Vol 134 (No12), Dec 2008

Flap based on Circumflex Scaplular 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

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 osseointegrated 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

Decreased range of motion of shoulder

Difficult for 2 team approach

Limited in amount of bone harvestable

Scapular Free Flap M. Bak et al. / Oral Oncology 46

(2010) 71–76

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

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 M. Bak et al. / Oral Oncology 46

(2010) 71–76

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

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

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

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

Reconstruction techniques involving the condyle are controversial

Oral competence, tongue and laryngeal mobility not significantly affected

Reconstruction of TMJ and condyle is usually disappointing

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

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

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

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

Components of the temporomandibular joint. AE, articular eminence and disc attachment; APF, attachment to the pterygotympanic fissure; CPW, capsule, posterior wall, D, disc; F, fascia; ILT, inferior head of the lateral pterygoid muscle; LPP, lateral pterygoid plate, PCA, posterior condylar attachment; SLT, superior head of the lateral pterygoid muscle.

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

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

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)

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

Patient with exposed bar 5 months after placement.

Exposure or Extrusion of prosthesis in the 3 patients with radiation exposure

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

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

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

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

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

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 Courtesy TMJI, INC. accessed on

http://www.tmj.com/products/tmj_total_custom.php

on 8/29/2010

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

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

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

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

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

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

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

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

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

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

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

Engroff, OOOOE, December 2005,663

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

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

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

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