WO2011016784A2

WO2011016784A2 - Frontozygomatic anchored distraction osteogenesis device

Info

Publication number: WO2011016784A2
Application number: PCT/SY2010/000002
Authority: WO
Inventors: Mohammed Aii Abbas Alkasem
Original assignee: Mohammed Aii Abbas Alkasem
Priority date: 2009-08-06
Filing date: 2010-01-26
Publication date: 2011-02-10
Also published as: WO2011016784A3

Abstract

This device anchored on zygomatic bone by tow screws per side and attached to frontal bone by single screw. The traction applied to the maxilla through the dentition by a rigid intraoral splint. The device components:- • The main frame : adjustable and consist of five segments. • Vertical bar. • Spindle units. • Distraction screws.

Description

Frontozygomatic anchored distraction osteogenesis device

Technica description of the invention

a~ Previous Technical State: 1- What is distraction osteogenesis? [1]

Distraction osteogenesis is a surgical technique for generating new bone by gradually separating two viable bone segments . The process involves creation of an osteotomy site while maintaining the integrity of the periosteum. The two bone segments are gradually separated, allowing a callus to form within the osteotomy site. Within this callus, osteoid tissue is deposited that eventually forms stable, viable, new bone. In addition to bone deposition, distraction osteogenesis causes a simultaneous expansion of the functional soft tissue matrix, which includes blood vessels, nerves, mucosa, fascia, skin, ligaments, cartilage, and periosteum. The concomitant change of the surrounding soft tissue generated by the distraction forces applied to bone is called distraction histogenesis .Fig 1

2-Defining protocols for distraction Osteogenesis:!!]

• The latency period of 5 to 7 days following surgery as the necessary time to allow for initial callus formation in endochondral bone.

• The rate for maxillary distraction within recent literature is 1.0 mm/day

• The rhythm: 0.5 mm twice per day

• The consolidation period, following active distraction, represents the period of rigid fixation allowing for adequate consolidation and maturation of the bony callus.Consolidation periods of 2 to 3 months were reported for maxillary and midfacial distraction cases

3- Whose patients can benefit from this device ?[2]

• It is known that 25% to 60% of all patients born with cleft lip and palate will require maxillary advancement to correct the maxillary hypoplasia and improve esthetic facial proportions.

• Maxillary advancement in patients with cleft palate includes maxillary osteotomy and miniplate fixation, along with interpositional bone grafting. Newly formed bone can provide good support and thus contribute to stability. Disadvantages of autogenous bone grafting include potential donor site morbidity, resorption, and infection of the bone graft with a tendency to relapse caused by decreased bone support of the maxilla after resorption or infection.

• The dense scar tissue present in most patients with cleft palate may account for some relapse that occurs after orthognathic surgery. Treatment of hypoplastic maxilla in patients with a cleft palate by conventional Le Fort I osteotomy and major advancement, the extreme discrepancies between bony segments after advancement in comparison with noncleft patients, and sometimes additional downward movement make stabilization difficult. The added effects of palatal scarring can result in significant postsurgical relapse.

® Cheung et al reported 22% relapse in the horizontal and vertical planes 28 months after surgery.

» Hochban et al reported 25% relapse after a mean 7.8-mm advancement after 12 months.

• Posnick and Dagys reported 23% horizontal relapse and 19% vertical relapse after a mean 6.9-mmadvancement.

• Erbe et al, after 59 months of follow- up, reported 40% relapse after 4.6- mm maxillary advancement.

• Hirano and Suzuki found that after 6.9-mm movement, 24.1% in the horizontal plane and 70% in the vertical plane relapsed.

• Thongdee and Samman reported on 30 patients with cleft lip and palate who had undergone preceding alveolar bone grafting, as well as long- term(mean, 62 mo) 3 -dimensional stability of maxillary surgical movement. Total relapse of surgical movement was 31% in the horizontal plane and 52% in the vertical plane, as well as 30% rotationally. Most relapses occurred in the first 6 months after surgery.

• The extent of horizontal and vertical relapse was found to correlate with the amount of surgical movement observed in the respective direction for the anterior maxilla. Therefore, treatment of severe maxillary hypoplasia, especially in cleft patients, has been unstable in both horizontal and vertical dimensions when treated by conventional Le Fort I maxillary advancement.

• On the other hand, distraction osteogenesis provides an alternative method for maxillary advancement in patients with a great tendency to relapse, such as cleft palate patients. Rachmiel et al, in an experimental study on noncleft adult sheep, advanced the maxilla 40 mm by distraction osteogenesis with only 7% relapse during 1 year of follow- up. a Histologic studies have shown formation of mature lamellar bone by distraction osteogenesis. This mature lamellar bone generated in the distraction site between the 2 bony segments may help to prevent relapse.

* Kusnoto et al, in a radiographic evaluation performed with the use of tomograms, found a pattern of bone formation in the pterygoid region after maxillary distraction with rigid external distraction (RED) devices. Bone trabeculae could be seen 6 weeks after active distraction . Therefore, a long period of consolidation is important in attaining stable results with the goal of preventing relapse. Distraction osteogenesis has been established as a predictable method to be used for maxillary bone elongation in clinical practice. With distraction, there is no need for bone grafting with donor site morbidity and risk of local infection and resorption. Concomitant generation of new bone occurs at the distraction site and in the pterygoid region, preventing relapse.

• Newly formed bone can provide good support, thereby contributing to stability. Recently, several long-term clinical follow-up studies that used

— "theπdistraction method for maxillary advancement showed stable results.

• Figueroa et al performed a long-term study over 3 years on 17 patients with cleft maxillary hypoplasia, aged 5.2 to 23.6 years, who underwent maxillary advancement with the use of RED and found that the maxilla was stable in the sagittal plane. Mean advancement measured at the anterior nasal spine (ANS) point was 9.6 mm, and significant vertical maxillary growth was noted over the 3 -year observation period. Cephalometric data from this study support the clinical impression of maxillary stability after maxillary advancement with RED in cleft patients.

• This effective and stable technique is now considered for all pediatric patients with severe cleft maxillary hypoplasia and for adolescent and adult patients with moderate to severe deformities. Results presented in recent studies show that distraction devices can successfully lengthen the maxilla with long-term stability as measured over 2 and 3 years .

• Distraction osteogenesis can provide an alternative method for maxillary advancement in patients with a tendency to relapse, such as cleft palate patients. The literature shows that patients who had distraction osteogenesis were younger than those who had orthognathic surgery. The amount of advancement was significantly greater in distraction cases as compared with conventional osteotomy.

• Conventional Le Fort I maxillary advancement can be performed only at the end of skeletal growth after puberty has ended. Use of the distraction method in early surgical treatment of growing children with retruded maxillae caused by the cleft palate has positive psychological effects on young patients and their parents. -Historical background:-[l] * The technique of bone lengthening by distraction osteogenesis was first introduced in 1905 by Codvilla , who reported successful elongation of a femur by the use of axial distraction forces.

However, the development and refinement of distraction osteogenesis was accomplished in the 1950s by Ilizarov , a Russian orthopedic surgeon who established a reliable protocol for the treatment of various orthopedic problems.

» Snyder et al. in 1973 were the first to report the use of distraction osteogenesis in the mandible. Using an animal model.

• McCarthy et al. in 1992 were the first to use distraction osteogenesis for the lengthening of a human mandible.

• Rachmiel A et al in 1995 wer the first to use dstraction osteogenesis for advancement of a cheep maxillary. [3]

• Polley et al [4] in 1998 initiated clinical studies to test the effectiveness of rigid external distractor (RED) on the treatment of human midfacial skeletal deficiencies which produced by martin . Fig 2

• Since that time, RED has been used extensively for the treatment of numerous human congenital and acquired craniofacial skeletal anomalies. - COMPLICATIONS ASSOCIATED WITH THE USE OFA HALOi-[S] • Complications associated with the use of a halo have been reported frequently in orthopedic literature and include loosening of stabilizing pins, soft tissue infection around the pins, severe pain associated with pins, scarring around the pins, dysphagia, neural injury, osteomyelitis of the skull, pin penetration with or without cerebrospinal fluid (CSF) leak, and cerebral or epidural abscess.

• The most frequent complications associated with halo pins are loosening and superficial infection. Garfin et al. reviewed 179 patients with halo usage: 36% experienced pin loosening, 20% acquired pin-site superficial infections, and skull penetration with dural puncture occurred in 1 patient.

Infection at the pin sites can cause pins to become loose, pain at the pin site, and halo loosening. • Glaser et al. reviewed 245 cases and found that 14 of them experienced pin-track problems.

® The use of the halo device in children is especially associated with a significantly high complication rate. Children are more prone to such complications because their skulls are softer, thinner, and more fragile and children are more active than adults. Dormans et al. reported complications of halo in 37 children and found an overall complication rate of 68%. Baum et al. found major problems in 5 of 13 children.

* The nature and distribution of these complications were similar to those reported by Garfin et al. in an adult population, except for a higher incidence of pin-site infection.

6- COMPLICATIONS ASSOCIATED WITH THE USE OF THE RED SYSTEMfSJ

® The growing use of the RED system for management of craniofacial dysplasias is accompanied by complications and risks, which have recently been reported in the craniofacial literature .

® Over the past 5 years, 6 patients treated by the RED system have experienced local fractures of their skull owing to penetration of stabilizing pins intracranially.

• In one case report, 2 episodes of pin penetration were recorded for the same patient: One episode was reported postoperatively during the predistraction period, and the other during the distraction process itself.

• The other 4 references reported 1 patient who suffered intracranial pin migration postoperatively during the predistraction process, 2 patients who exhibited pin penetration during the distraction process itself, 1 case where the pin penetrated the skull bone and cerebrospinal fluid leakage was noted immediately during removal of the RED head frame and 1 case of skull fracture associated with traumatic injury due to a fall affecting the RED.

• These complications evoked prevention and risk management considerations in order to minimize the side-effects occurring during the use of these efficient devices .

• The specific design of the RED horseshoe device has shifted the pin sites toward the temporal region, which is much thinner. Skull thickness measurements taken in infants have shown that there is no safe zone to place the pins. Literature available on complications associated with rigid external distraction (RED) Reference Complication: [5]

• Le et al. Two episodes of RED complications in the same patient: 0.5 cm intracranial pin penetration postoperatively and predistraction; 1.5 cm intracranial pin penetration 3 weeks postoperatively during distraction process.

• Rieger et al. Traumatic skull fracture from a fall on RED .

® Mavili et al. Two patients with intracranial pins penetration.

• van der Meulen et al. Intracranial pin penetration with leakage of cerebrospinal fluid during RED removal, 6 weeks postoperatively and 2 weeks postdistraction process.

• Aizenbud and Rachmiel: 0.5 cm intracranial pin penetration postoperatively and predistraction.

» Elsheikh Y . One patient (6.7% from 15 pateints) had trauma to the head after she was discharged from the hospital and this resulted in intrusion of scalp screws through the skull bones.Fig3 b-Tlιe invention :

» The success of distraction osteogenesis as a treatment entity has largely resulted from advancements in the armamentarium;, modification of the surgical techniques, and enhancement of the osteogenic process. Current research continues to focus upon these areas.

Because of:

1- Treatment of severe maxillary hypoplasia, especially in cleft patients, has been unstable in both horizontal and vertical dimensions when treated by conventional Le Fort I maxillary advancement.

2- On the other hand, distraction osteogenesis provides an alternative method for maxillary advancement in patients with a great tendency to relapse, such as cleft palate patients.

3- The rigid external distraction (RED) system is the most common external distraction device for the advancement of severe retrusive maxilla especially in cleft palate patients.

4- The use of RED device is accompanied by many complications and risks. Review of the literature on complications of the use of halo revealed that most complications are pin related. Complications with the use of RED have mainly included the penetration of intracranial pins. Risk management and preventive considerations propose several modifications to prevent the side effects when using RED , that was our invention which anchored on zygomatic bones and attached to frontal bone , which called frontozygomatic external anchored distractor(F-ZED).

An indeed, this distractor developed in two stages :-

First : zygoma anchored stage (ZED):In this device we encountered a problem that draw down the level of the device specially for children, which reduce the effectiveness of traction in advancing the maxilla.Fig 4 Second : frontozygomatic anchored stage (F-ZED). In this device we attached the anterior part of the device to a screw retained in nasion (frontonasal suture ) which increase the device supported .Fig 5

FrontoZygomatic External Distractor(F-ZED)

® It is a rigid, external, an adjustable system manufactured by author.

β It made up of titanium except for Spindle units are made up of graphite.

» Its components are:- Fig 6

1- Main frame: This is made up of five mobile an adjustable distractor segment :- a- Fixed segments : they are two segments (right& left) which are in turn fixed to zygomatic bone by two titanium fixation screws on each side.

b- Adjustable segments: they are two segments (right&left) which hold between the fixed segments and intermediate segment there are more than one measures of this segments to adapt to variation faces.

c- Intermediate segment : one segment which fixed the vertical bar , and attached to frontal bone by wire.

2- Vertical bar one vertical bar which holds between the main frame and the traction unit .

3- Spindle units They are two units which run too and fro upon a titanium rod, by adjusting the distance between them we can get the required transverse maxillary rotation.

4- Distraction screws They are two screws which pass through the spindle units to reach the connecting wire which is attached the maxilla, so when we turn these screws we apply traction force to the maxillae.

5- Tools and accessories one for the patients which is called (Patient Socket Wrench,

Hexagonal.

Preoperative procedures:-

• In order to apply traction to the maxilla through the dentition , a rigid intraoral splint needs to be fabricated . Orthodontic bands with 0.050 inch headgear tubes are fitted either on the second primary molars

(children under 6 years) or first permanent molars and first premolar and an alginate or compound impression is taken of the maxillary arch.

• If needed, a transpalatal bar can be added to increase rigidity.

Connecting wires between the labial and palatal arches through the embrasures between the lateral and canine teeth bilaterally or in any other area where the wire can be passed without interfering with the occlusion may also be incorporated

Surgical procedures :-

• An upper buccal sulcus incision was performed between the two upper first peπnanent molars.

• Elevation of mucoperiosteal flap till exposing the infraorbital nerve, maxillary buttress, pyriform aperture on each side followed by meticulous dissection of nasal mucosa.

• High LeFort I osteotomy which was fashioned below the infraorbital nerve avoiding injury to the teeth buds. In all cases we used oscillating electrical saw, complete osteotomy was obtained by down fracture of maxilla after septal disjunction and pterygomaxillary disjunction, to assure the total freedom of the maxilla.

• Closure of upper buccal sulcus incision by vicryl 4/0. ® The last step is fixation of frame to the zygomatic region by 2 screws on each side, these screws applied by drilling .

• After application of F-ZED and connecting wire to it we do test advancement to ensure free maxillary mobility .Fig 7

» Finaly we removed every components of the device except fixation segments to facility the use of resuscitation facemask and to help patient to be more comfortable during latency period.Fig 8

Placement of the F-ZED system :-

• Assemble the F-ZED components.

» Adjust transverse dimension of the F-ZED by choosing suitable measure of an adjustable segments . Lock the fixed segments into the desired position. There should be approximately 1-2 cm distance between the inner aspect of the F-ZED and the surface of the skin.

® Adjust vertical position of the F-ZED, the F-ZED should parallel the Frankfort Horizontal Plane

• Inter of the titanium fixation screws through the corresponding hole in the fixation segment until the pointed end of the screw had embedded about 2cm in the zygomatic region by drill , 2 titanium fixation screws per side are required to secure the F-ZED.

® Fixed a screw in nasion point and connected wire around it .

• After insertion of wire in the holes of the distraction screws and connected it to a rigid intraoral splint , we do a trial of full distraction to ensure the freedom of the maxilla and the integrity of the connections, after that we got the maxilla back again in its initial place exerting no tension on it and removed every components of the device except fixation segments.

Postoperative details :-

• In all patients, active distraction started on the seventh day postoperative, distraction began at a rate of lmm per day, and rhythm was twice per day, one revolution of the screw is equal to 1/2 mm.

Consolidation phase :-

• After completion of the distraction the F-ZED was left in place passively without distraction for three months to allow for consolidation of the gained results, during this period the patients were monitored weekly for any changes in the position of the F-ZED or any looseness of the pins which may alter the desired results and to control of the problem that could occur.

Removal of the F-ZED:-

® Generally, F-ZED was removed without any anesthesia or under local anesthesia. Removal of the F-ZED was performed by simply loosening the titanium screws on both sides of the F-ZED until it can be gently removed away from the face.

Economical gain:-

F-ZED device is cheaper than RED so it is suitable and available choice for Syrian and Yemeni people .

Claims

Claims to be protected:-

1- Frontozygomatic anchorage :it is the first to use in distraction osteogenesis which increases estability of the distractor and it is saver for us especially for children because of :

a. Anchorage screws far from the brain .

b. Anchored screws location (zygomatic area) easily to be cleaned which reduces possibility of infection .

2- Dependent on (1) vertical bar which is hold between the main frame and the traction unit so we can increase the face vertical dimension.

3- Dependent on (1),(2) we can add traction units .They are two units which run too and fro upon a titanium rod, by adjusting the distance between them we can get the required transverse maxillary rotation , in addition we can activated one side more than the other to correct face asymmetric .

4- Adjustable main frame which made up of five mobile segments:- a- Fixed segments : they are two segments (right& left) which are in turn fixed to zygomatic bone by two titanium fixation screws on each side.

b- Adjustable segments: they are two segments (right&left) which hold between the fixed segments and intermediate segment there are more than one measures of this segments to adapt to variety of faces measurement .

c- Intermediate segment : one segment which fixes to the vertical bar , and attached to frontal bone by wire.

5- Dependent on (4) we removed every components of the device except fixation segments at the end of operation to help patient to be more comfortable during latency period and facilitate the use of resuscitation facemask .