Maxillofacial Implants for oral & maxillofacial surgery.pptx

implants

1. Maxillofacial Implants Moderated By: Presented By: Dr. G.K Thapliyal Dr. Nakul Chaudhary Dr. Ashish Sharma PG 2 nd year Dr. Himanshu Bhutani

2. Introduction Preoperative virtual planning and the use of patient specific implants enable exact reconstruction of orbital fractures. Results and experience of reconstruction of isolated orbital fractures with patient- specific implants, according to the Helsinki protocol. In the surgical management of such fractures, dissection to the posterior margin and reconstruction of the slope of the orbital floor are key factors in the prevention of residual enophthalmos and recurrent diplopia . Since the anatomy of human orbits is not identical, and the morphology of fractures differs ; stock meshes are therefore need to be cut and shaped at the time of operation .

3. 15-Isolated orbital fractures - presented between 1 st Jan -30 th Nov 2017. Exclusion criteria : Extension of the orbital fracture to the orbital rim Secondary reconstruction Reconstruction associated with treatment of a tumour . Reconstructions with a non- customised titanium mesh. Virtual planning : Patient-specific implants were designed preoperatively and engineered using the CAD of the Planmeca ProModel ™ system ( Planmeca Ltd). They used mirroring of the unaffected contralateral side as reference for the virtual reconstruction .

4. The borders of the fractures were localised and implants designed to rely on at least three intact shelf structures of the orbit : Anteromedial Anterolateral Posterior Anteriorly it was supported on the inner surface of the anterior orbital rim. The lateral side of the implant was extended to the infraorbital groove, but not in it or over it. The implants were designed to rely on the bony support points and orbital shape with sufficient stability, eliminating the need for further fixation .

5. The virtually planned design and fit of the implant was confirmed on a 3-D model of the skull by the surgeon before the operation. Manufacture of the implant: The patient specific implants were CNC(Computer Numerical Control) milled from titanium alloy blocks to a thickness of 0.3–0.4mm. Apertures of 2.0–3.0mm with 1mm spaces were used for reconstruction of the frame. A small eminence on the anteromedial side of the plate next to the lacrimal foramen(arrow) was designed for better orientation during the operation .

6. Measurements of the orbital volume : The one-click method developed by Disior Ltd was used and the orbital volume was defined by marking the outer orifice of the optic canal in the apex of the orbit. A virtual sphere is inserted in the middle of the orbital cavity which was allowed to expand until its surface was aligned with the boundaries of the orbital cavity. Its volume therefore consists of the optical canal in the apex and the orbital rim anteriorly . The expansion of the sphere must stop on the boundary of the true orbit. The orbital volumes were analysed using proprietary algorithms ( DisiorLtd ) and were solved numerically .

7. Measurement of the position of the implant: Virtual 3-dimensional models of the patients from before and after the operation were super-imposed. Differences between the postoperative position of the implant and the virtually planned position were measured in 3 sites: anteromedial , anterolateral , and posterior in 3 dimensions (lateral, posterior and superior). Statistical analysis: The data was analysed with the aid of IBM SPSS Statistics for Windows (version24,IBMCorp). The results were given as mean or range and the significance of differences were calculated with the chi squared test or Fisher’s exact test, as appropriate .

8. Indications for surgery were a fractured area of more than 1.5cm 2 with dislocation of 4mm or more and diplopia during daily activities. The transconjunctival approach was used in all patients and none had bilateral reconstruction or reconstruction of the medial wall .

9. Introduction Orbital roof reconstruction may be necessary after extensive resection of spheno -orbital meningiomas or other tumors or following high-impact trauma. Although small orbital roof defects may not need reconstruction, an implant or graft may be indicated for larger roof defects. Several materials have been used for orbital reconstruction which includes autologous bone, titanium, porous polyethylene, silicone, and nylon among others. Nylon foil, or Supramid has been shown to be a safe and effective material in the reconstruction of orbital floor and medial wall fractures. To present a technique for reconstruction of the orbital roof using nylon foil immediately after tumor resection.

10. Surgical technique After general anesthesia was induced, the patient was positioned supine with the head secured in a Mayfield headrest. The neurosurgical team performed a fronto - orbital- zygomatic or frontotemporal craniotomy depending on the extent of tumor involvement. The frontal lobe of the brain was retracted and the tumor was resected with care to preserve both the uninvolved dura and brain above and the orbit soft tissues below. In all cases, the tumor involved the frontal and lesser wing of sphenoid bone and resection caused a complete roof defect.

11. A 0.35-mm nylon foil ( Supramid , S. Jackson, Inc.) sheet was prepared for implantation to bridge the roof defect. The implant was cut in a custom configuration to allow 7 - 10 mm of rest onto the remnant medial and lateral wall. The dimension of the ovoid implant was approximately 4–5 cm × 3–4 cm and with a slight curvature to recapture the natural bony anatomy of the superior orbit and to achieve a barrier between the superior orbital soft tissues and dura above.

12. The implant was secured to the remnant superior orbital rim with titanium screws in 1 st case. The implant was secured with two 4-0 polyglactin sutures to the orbital walls with drill holes in 2 nd case. Implant was stable against the remnant orbital walls through a tamponade effect of soft tissues on either side of the device and no sutures or screws were needed in the 3 rd case. Care was taken during placement of the implant to prevent impingement of any extraocular muscles or orbital tissue.

13. With the orbit reconstructed, any remaining tumor in the middle cranial fossa was resected . The brain and dura or dural patch or both were then seated onto the nylon foil below. The craniotomy bone flap was replanted and secured with titanium mesh plates, or a custom polyethereketone (PEEK) implant (Stryker, Portage, MI) in 1 st case undergoing adjunctive cranioplasty for a depressed skull defect. The scalp wound was then closed in a standard fashion using sutures.

14. Results The patients included 2 males and 1 female and ranged in age from 39 to 64 years (mean, 51.7 years). Symptoms and signs included decreased vision or vision loss, pain, headache, ptosis , limitation of extraocular movements, proptosis , and visible or palpable mass. All patients had stable visual acuity after surgery. Proptosis , restriction of extraocular movements and hypoglobus improved significantly postoperatively in the 2 patients who presented with this finding. Postoperative imaging showed appropriate placement of the implant without herniation of intracranial tissues into the orbit. There were no postoperative complications related to the nylon foil orbital roof reconstruction.

15. Patient 1 A 38-year-old female presented with a history of right periocular swelling, pain, and decreased vision progressing over 6 months. External examination revealed a bony mass along the frontozygomatic suture extending posteriorly toward the preauricular area without gross globe displacement was seen. MRI demonstrated a right temporal bone tumor with surrounding soft tissue enhancement and thickening with medial displacement of the lateral rectus and optic nerve.

16. Radiographic pre- and postoperative. A) Preoperative T1 axial and B) coronal MRI of the brain and orbits showing a right temporal bone tumor with surrounding soft tissue enhancement and medial displacement of the lateral rectus muscle and optic nerve.

17. The patient underwent right fronto-orbito-zygomatic craniotomy for tumor resection and optic nerve decompression. The nylon foil implant was cut to fit the roof defect and with a shallow titanium screw, the implant was secured to the remnant superolateral orbital rim bone previously removed as a bone flap. The superolateral rim with attached nylon foil was then secured to the osteotomy sites at the lateral and superomedial rim using plates and screws. Postoperative CT scan showed improvement of the orbital wall contour without displacement of the lateral rectus and optic nerve with the nylon foil implant in a good position.

18. C) Coronal CT image showing a spiculated sunburst pattern along the right lateral orbit and temporal bone. D) Postoperative coronal CT image showing postsurgical changes with the tumor removed and improved anatomical position of the orbital contents.

19. MRI 7 months postoperatively demonstrated no evidence of progressive disease and stable postsurgical changes with good placement of the orbital roof nylon foil implant.

20. Patient 2. A 64-year-old male with a history of 4 prior resections of a left WHO grade II meningioma presented for possible debulking of the recurrent meningioma . Symptoms of blurry vision in the OS associated with diplopia for 20 years. External examination showed massive proptosis and hypoglobus with ptosis of the left upper eyelid. MRI showed a large mass involving the left frontal bone, dura , and orbit with significant mass effect on the left globe and superior and lateral rectus muscles. The patient underwent neurosurgical tumor resection via frontozygomatic craniotomy approach.

21. For the resultant orbital roof defect, a nylon foil implant was trimmed to the appropriate size to fit the roof defect and was then secured to drill holes on the remnant medial and lateral orbital walls using 4-0 polyglactin suture. A PEEK ( polyethereketone )cranial implant that was designed to reconstruct the superior orbital rim and cranial defect was then secured into position. Two weeks postoperatively, the patient showed improvement in his extraocular movements, hypoglobus , and proptosis . Unrelated to the orbital roof reconstruction, the postoperative course was complicated by a left temporal seroma requiring drainage 1 month after surgery.

22. Patient 3. A 52-year-old male with a history of visual loss in the OS for 2 years presented to the emergency department with progressively worsening eye pain more than 2 months. On examination, the patient had NLP with intraocular pressure of 48 in the OS and extraoccular movements showed complete restriction in all directions of gaze. External examination showed significant proptosis , hypoglobus , and complete ptosis . MRI showed an extensive skull base tumor invading the orbit, and anterior and middle cranial fossa , and encasing the carotid arteries bilaterally.

23. During tumor resection, a portion of the left superior rim was removed, along with the orbital roof, and superolateral orbital wall. The superior rim was repositioned with a curved titanium plate and screws. A nylon foil implant was trimmed to fit the roof defect and was carefully placed into its appropriate position and was stable against the remnant orbital walls through a tamponade effect of the orbital soft tissues. Following the surgery, the patient still had NLP due to his lack of visual potential prior to the surgery but demonstrated improved hypoglobus and proptosis .

24. Introduction Auricular reconstruction has always been a challenging procedure for surgeons. The autologous reconstruction at two stages described by Tanzer RC remains the reference technique, however it requires specific experience to obtain a satisfying result. New technologies have not yet become the first choice in atrial reconstruction. Nevertheless, they offer therapeutic alternatives to patient based on their medical history and treatment involvement. This article aims to describe the four-year outcome of a surgical procedure implanting a patient specific epithesis system in two patients.

25. Manufacturing of custom plate After virtual 3D reconstruction of the anatomy and mirroring of the healthy ear, the positions of the three Locator attachments were optimized in the software to embed them as accurately as possible in the planned episthesis antihelix . Three attachments appear to be the best compromise from our experience. Ten osteosynthesis screws were then virtually placed around the abutments to ensure bone anchorage . The position of these screws on the mastoid and squama was optimized based on bone stock and surgical approach. It was decided to use 5.5 mm long screws to provide monocortical fixation and safety was virtually assessed.

26. After validation of the virtual project by the surgeon, the custom plate was manufacturing in commercially pure titanium grade 2 by selective laser melting and submitted to anodic oxidation. After cleaning, the plate was delivered non-sterile to the hospital within three weeks. The plate was then autoclaved and brought to surgical theatre. Locator1 attachments of different lengths were prepared upfront in order to allow for adaptation to actual skin thickness

27. Virtual planning of the personalized plate position with the three implants and the position of the epithesis

28. Surgical technique The plate was placed while the patients were under general anesthesia with the following surgical procedure: Lift of an arc-shape skin flap with subperiosteal detachment. Osteosynthesis of the plate of which positioning is facilitated by its custom shape and by checking the position of the three attachments relatively to the francfort plane. Screws were chosen and placed according planning. Surgical closure is performed in two layers without drain. Pseudo-draining is possible through transcutaneous passage of attachments performed with a thin tip electric bistoury through skin flap. Post-operative antibiotic therapy is prescribed during ten days as a precaution and a cutaneous antisepsis is recommended twice daily.

29. Manufactoring of episthesis For both patients, the episthesis was put in place two months post-operatively. It was decided to use dental type acrylic resin for ease of use and durability reasons. It also allows to have the episthesis prepared by a dental laboratory instead of an anaplastologist . A mold of the future episthesis was prepared from the anatomical model with heavy viscosity silicone. The hollow shape allows for the integration of the attachment’s female parts with an impression using flowable silicone directly on the patient.

30. Model, used as a support for the realization of the epithesis in acrylic resin, obtained by 3D printing from mirroring the contralateral ear. A. anterior face; B. posterior face with anchoring zone.

31. The first patient is a 55 years old woman subjected to an outer ear loss from an oncological resection previously replaced by a skin flap (clinical result).

32. Second patient is a 48 years old man showing outer ear loss from a trauma.

33. Discussion Computer aided techniques, virtual planning and use of patient specific implants enable anatomically exact reconstruction of the orbital floor in primary trauma. These methods should be considered for larger studies in primary reconstruction of facial fractures. Currently patient-specific implants are used for repair of all isolated fractures of the orbital floor except for emergencies, or when the need for operation is uncertain, or in children in whom we prefer to use resorbable materials. When using mirroring as a reference for virtual planning, the possible chance of a previous fracture of the contralateral side must be considered .

34. Preoperative errors in planning should be carefully avoided, as milled titanium is a rigid material that does not allow intraoperative bending. Despite adequate bony reconstruction, the changes in the soft tissues may limit the aesthetic and morphological outcomes. Virtual planning and customised orbital reconstruction will allow accurate over correction in the future. Porous polyethylene with embedded titanium ( Medpor Titan , Stryker, Kalamazoo) offers purported benefits of 2 materials . This implant material is not only easily contourable but is durable and allows for porous fibrovascular ingrowth and microscrew fixation to the orbital rim.

35. Nonporous polyethylene barrier sheets may have similar benefits as nylon foil implants . The nonporous side is to be placed adjacent to the orbital tissues to prevent orbital soft tissue integration, whereas, the porous polyethylene side is placed against the bony defect allowing for tissue integration that may secure the implant . Nylon foil ( SupraFOIL , Supramid , Alexandria , VA ) implants are nonabsorbable sheets composed of polyamide and are available in thicknesses ranging from 0.05 mm to 2 mm . They are rigid enough to provide good support preventing enophthalmos , but also have the flexibility to conform well to the shape of the orbit.

36. The use of the nylon foil implant eliminates the second surgical site and other morbidity associated with autologous bone grafts and is certainly significantly less costly than custom 3-dimensional implants. Limitations to this surgical technique ; if the orbital rim is missing after tumor resection, there are few resting points to stabilize the implant. The decision to fixate the implant is intraoperative based on its stability against the remnant orbital walls . Nylon foil was an effective material for reconstruction of large orbital roof defects after tumor resection.

37. The pre-operative planning in ear episthesis makes the technique applicable in almost all cases because the management of the parallelism of the attachments is no longer a problem and the position of these parts in the episthesis can be optimized . Potential problems with lack of bone on the temporal bone under episthesis are also avoided as monocortical screws can be moved to safe areas. Surgery is more faster and safer, leading to a faster recovery time, both on native skin and grafted skin, allowing earlier placement of the epithesis . The acrylic prosthesis remains fragile in its daily use as both patients have already broken their epithesis .

38. Thus, the costal cartilage and its difficulties of anatomic conformation to obtain an auricular model can be replaced by other materials such as polyethylene. Given by the latest publications, 3D printing seems to provide new opportunities to address these mechanical constraints . 3D planning provides valuable assistance to the surgeon and eliminates several constraints related to the placement of bone implants . It assist the surgical procedure and improves both the aesthetic and functional result. The difficulties of material maintenance and longevity of the epithesis still persist.

39. Thankyou