Mandibular reconstruction

FCPS,MOMS,MRCS, FDS STUDENTS

1. Mandibular Reconstruction Dr Jameel kifayatullah Senior lecturer Khyber college of dentistry ,Peshawar ,Pakistan

2. Goals of mandible reconstruction 1)Restore mandibular continuity 2) Restore alveolar bone height 3) Restore osseous bulk 4) Reconstruct the lower facial contours 5) Preserve the TMJ and its relationship within glenoid fossa 6)Create a neomandible that is suitable for dental prosthetic rehabilitation 7) Anatomically and functionally restore adjacent soft tissue defects( i.e tongue,cheek.lips )

3. Rationale for reconstruction  Large complex defects can be created during resection Without reconstruction, patients may have functional and cosmetic impairments. The surgeon redefine the preoperative functions and facial aesthetic units to allow the patient to return to a normal family and social life The approach includes the placement of dentures or osseointegrated implants to help shape the face and to assist with mastication and verbalization.

4. Criteria for a successful mandibular bone reconstruction Restoration of mandibular continuity Restoration of alveolar bone height Restoration of osseous bulk Maintenance of osseous content for atleast 18 months Restoration of acceptable facial form Acceptability of endosseous implants Recoverable ,non debilitating donor site surgery

5. How To achieve optimal functional and aesthetic results replace the skeletal buttresses restore the external/internal soft tissue envelope eliminate fistulas provide a foundation for dental rehabilitation.

6. JEWER etal Classification Central defects including both canines are designated “C” Lateral segments that exclude the condyle are designated “L” When the condyle is resected together with the lateral mandible, the defect is designated “H”, or hemi mandibular .

7. Jewer Etal classification Eight permutations of these capital letters—C, L, H, LC, HC, LCL, HCL, and HH—are encountered for mandibular defects. The significance of this is that a lateral defect can be reconstructed with a straight segment of bone, whereas a central defect would require osteotomies

8. CLASSIFICATION ACCORDING TO TYPE OF DEFECT

9. Jason k potter classification Classification of mandibular defects Alveolar defects :Loss of alveolar segment without loss of mandibular continuity Anterior defects : Segmental defect incorporating the region of mandibular symphysis or extending from cuspid to cuspid Lateral defects :segmental defects involving the mandibular body region or extending from mandibular cuspid to the retromolar region Posterior defects: segmental defects involving the ramus and mandibular angle with or without loss of condylar process

10. Timing of reconstruction Primary/Immediate :Reconstruction may be primary (performed at the time of resection of the tumor) Secondary (performed as a separate procedure after resection

11. ARGUMENTS AGAINST DELAYED RECONSTRUCTION unique challenge for the surgeons due to the presence of soft tissue scarring and the contracture of the resected end of the mandibular tissue. This often hinders the surgeon’s ability to predict the length and the amount of mucosa required intraorally .

12. ARGUMENTS IN FAVOR OF DELAYED RECONSTRUCTION immediate reconstruction covers the primary site, decreasing the ability to detect recurrence. extended length of surgery required for primary reconstruction possibility of seeding cancer cells in newly dissected tissue planes presumed increased risk of infection from salivary contamination.   Oncologic margins, especially the bony margins, are cleared by means of permanent sectioning before safe restoration can be achieved. Frozen sections are fairly reliable for soft tissues, but they are less suitable for mandibular margins.

13. IMMEDIATE RECONSTRUCTION reduction in the number of surgical procedures and hospital stays A shorter time during which the patient has deformity and morbidity from lack of function the protection and preservation of vital structures a reduced cost of treatment, the rapid oral rehabilitation with a timely return to a normal social lifestyle offers significant advantage over secondary repair by preventing the wound from scarring while obtaining optimal functional and aesthetic results for the patient. Immediate reconstruction significantly improves QOL and that most patients prefer immediate reconstruction 

14. Reconstructive options Alloplastics ( Alloplastic implants) Nonvascularized Bone Grafts (Free Bone) Revascularized Bone (Free tissue transfer) Distraction Osteogenesis

15. ALLOPLASTS Plates are used if the prognosis is thought to be poor, or if the patient was medically or surgically unsuitable for vascularised bone reconstruction

16. Reconstruction plates Reconstruction plates are rigid plates that are applied along the lower border of mandible Made with the intention of bridging a defect Stabilizing remaining segments Maintaining occlusion and facial contour Frequently used to fix corticocancellous blocks or vascualrised bone grafts to remaining mandible

17. Reconstruction Plates titanium plates more popular because of biocompatibility overriding principle is to have one single plate of sufficient thickness and width to hold the fragments in place. This implies plates approximately 3 mm thick and 5 mm wide A special feature of the modern types is the locking screw which minimize compression between the plate and the underlying bone, thereby optimizing the vascularity surrounding the graft Locking plates are associated with significantly fewer complications than non-locking plates when used in the symphyseal region.

18. Reconstruction plates Complications associated with plates: wound dehiscence with plate exposure, infection from loosening and breakage of screws, plate fracture and unsatisfactory facial contour. Radiography and computed tomography scans in particular show backscattering which causes diagnostic problems. Irradiation therapy is equally hampered by the plates. It has been shown that titanium causes the least amount of artefacts in magnetic resonance imaging compared to stainless steel and vitallium

19. Reconstruction plates   Indications for plate : a patient whose medical condition precludes a prolonged operation time to carry out a microsurgically anastomosed flap, or in whom the vascular system does not allow for a microvascularanastomosis . reconstruction plates should be used only in those selected patients with a small (<6 cm) lateral mandibular defect. Some surgeons prefer plate fixation as a first means to stabilize the mandible and will carry out a secondary reconstruction a year later.

20. Non- vascularised bone grafts Used to reconstruct defects that are less than 6 cm in length provided that the soft tissues are in good condition(not irradiated) and in medically compromised patients who cannot tolerate free tissue transfer Non vascular bone grafts should be reserved for lateral or posterior lateral defects smaller than 6 cm without extensive soft tissue loss in patients who have not or will not receive radiotherapy Donor sites : intraoral and extraoral Extraoral donor sites: cranium,ilium,tibia or femur Intraoral donor sites: symphysis,ramus,body or zygomatic bone  

21. Schema of the bare bone graft with a vascularised iliac crest. The vascularised iliac crest is transferred intraorally to the position of the osteotomized stump upwardly. Suture is placed through the lingual and buccal sides of the mucosal stump and the bone. Next, the bone graft stump is covered with a collagen sheet and ointment gauze

22. Microvascular free flaps/free tissue transfer Vascularised bone flaps are treatment of choice for defects greater than 6 cm and in presence of irradiated tissues Vascularised bone flaps achieve a higer incidence of primary bone union and implant success rate Vascularised bone flaps have shorter healing time and complications like resorption and infection are greatly reduced The donor sites used most commonly for mandibular reconstruction are radial forearm,scapula ,iliac crest and fibula.

23. FACTORS AFFECTING THE OUTCOME OF MANDIBULAR RECONSTRUCTION (august) Length of mandibular defect Timing of reconstruction Radiotherapy Postoperative recipient site complications Malignant diagnosis Intraoral communication

24. Radial forearm flap  ARTERY : based on radal forearm artery VEINS ;vena comitanta or subcutaneous forearm veins LENGTH OF BONE HARVESTED :10-12 cm Advantages : 1) excellent pedicle length and diameter 2) reliable skin paddle which large,thin and pliable ideal for intraoral lining Complication: Fracture of radius at donor site Disadvantages: the transplanted bone is thin not allowing multiple osteotomies to adapt to the shape the mandible the height doesnot favor the placement of implants

25. RADIAL FOREARM FLAP

26. Anterior mandibular defects Anterior mandibular (C) defects will typically constitute an absolute indication for reconstruction using vascularized bone. Due to multiple osteotomies required to contour the bone, fibula should be considered the first choice for reconstruction of anterior or large defects.

27. Lateral Defects Lateral defects smaller than 6 cm and associated with benign disease—non vascular bone grafting in patients not desiring immediate reconstruction Lateral defects 6cm and larger associated with larger soft tissue loss and having a History or need for RT ---reconstruct with vascularised bone graft

28. Scapular flap Osseous defects of mandible upto 14 cm in conjunction with large cutaneous or intraoral mucosal defects reconstructed with this flap Through and through oromandibular defects of cheek combined with sagittal mandibular defects reconstructed with this flap Disadvantages: need for repositioning the patient Lack of sensation in the flap Limited bone stock for osseointegration esp in females

29. Scapular flap

30. Deep Circumflex Iliac Artery Flap Ideal flap to restore the width and vertical dimension of the mandible Provide an appropriate bed for placement of dental implants The internal oblique muscle is harvested along with ileac crest and is allowed to epithelialize to serve as soft tissue coverage for the graft intraorally Skin paddle can be taken with this flap Disadvantages : Relatively short 4-5 cm vascular pedicle,higher potential donor site morbidity and bulk the lack of segmental perforating vessels which limits its use for osteotomies . Patients may be slow to ambulate after surgery and permanent gait disturbance may occasionally occur

31. DCIA FLAP SURGICAL LANDMARKS: ASIS,Pubic tubercle and ileac crest Skin paddle:12×6 cm Bone segment 8×18 cm may be harvested

32. DCIA FLAP

33. Fibula free flap ARTERY : peroneal artery VEINS ;peroneal vein LENGTH OF BONE HARVESTED : upto 25 cm Standard landmarks: fibula head,lateral malloelus , posterolateral intermuscular septum Advantages : 1)The width and height of the flap are well suited for mandibular reconstruction 2 ) better suited for placement of dental implants 3) The fibula free flap remains the first choice for the edentulous mandible or for extensive mandibular resections Disadvantages: Donor site morbidity is relatively mild but pre-existing peripheral vascular disease will preclude use of this flap The height of bone is inadequate relative to a dentate mandible which can be a problem when dental implants are planned for occlusal rehabilitation

34. Distraction osteogenesis Distraction osteogenesis is a process in which new bone formation is gradually induced by an opening (distraction) device between two bony surfaces. For mandibular reconstruction, a technique known as transport disc distractionosteogenesis (TDDO) used. A segment of bone is cut adjacent to the defect and moved gradually across the defect by a mechanical device. New bone fills in between the two bone segments. The pieceof bone being moved or transported is referred to as the transport disc

35. DISTRACTION OSTEOGENESIS

36. Distraction Osteogenesis External devices were employed in early cases but these caused problems of facial scarring along the pintracks . To overcome this problem, an internal plate-guided distraction device was described by Herford in 2004 ADVANTAGES : Obviates the need for harvesting bone from a donor site It offers the potential of growing bone and soft tissue from the native site and placement of dental implants is possible

37. DEFECT WISE RECONSTRUCTION Anterior Defects Anterior defects( symphysis ) reconstructed with reconstruction plates and soft tissue flaps are at high risk of failure Vascularised bone flaps procedure of choice for anterior region The one drawback is that they are difficult to contour

38. Lateral Defects Lateral defects smaller than 6 cm and associated with benign disease—non vascular bone grafting in patients not desiring immediate reconstruction Lateral defects 6cm and larger associated with larger soft tissue loss and having a History or need for RT ---reconstruct with vascularised bone graft

39. Free iliac crest bone graft.

40. Free bone graft placed in the segmental defect.

41. Posterior defects Less complicated to reconstruct unless involving condylar process Posterior defects can impact facial form,including posterior vertical height of the mandible Create a more significant impact on mandibular range of motion because of relationship with TMJ and muscles of mastication

42. Posterior defects Can allow Collapse of defect without reconstruction dictated by patients clinical condition The local and patient factors which determine the type of graft for reconstruction of posterior defects are: volume of tissue loss,disease process,status of temporomandibular joint and RT The type of graft used dependent on above factors are costochondral / corticocancellous grafts,alloplastic prosthesis,or vascular bone flaps

43. Posterior defects Preservation of condylar process when oncologically feasible may be stabilised to graft with plates when adequate condylar structure is present or with wire fixation for smaller segments

44. Tissue-engineered transplants The engineered graft allowed to heal in the trapezius muscle and subsequently transplanted to the recipient side using microvascular anastomosis .

45. MODULAR ENDOPROSTHESIS An endoprosthesis is a metallic device that replaces diseased bone in long bones and is fixed internally with bone cement within the medullary space of the remaining healthy bone. There is no need for screw fixation. The variable length of the bone gap can be bridged by using modules that allow for accurate three-dimensional reconstructions . The modules are connected by a locking system.

46. Mandibular endoprosthesis