- Email: [email protected]
Biodegradable fixation of mandibular fractures in children: Stability and early results
Biodegradable fixation of mandibular fractures in children: Stability and early results Kaan C. Yerit, MD, DMD,a Sibylle Hainich, MD, DMD,b Georg Enislidis, MD, DMD,a ¨ ckher, MD, DMD,a Dritan Turhani, MD,a Clemens Klug, MD,a Gert Wittwer, MD, DMD,a Michael O c c Gerhard Undt, MD, DMD, PhD, Christian Kermer, MD, DMD, Franz Watzinger, MD, DMD, PhD,c and Rolf Ewers, MD, DMD, PhD,d Vienna, Austria MEDICAL UNIVERSITY OF VIENNA
Objective. The aim of this study was to assess the safety and efficiency of biodegradable self-reinforced (SR-PLDLA) bone plates and screws in open reduction and internal fixation of mandible fractures in children.
Study design. Thirteen patients (5 female, 8 male; mean age 12 years, range 5-16 years) were operated on various fractures of the mandible (2 symphyseal, 6 parasymphyseal, 4 body, 3 angle, 1 ramus, 2 condylar fractures). The mean follow-up time was 26.4 months (range 10.9-43.4 months). Intermaxillary fixation was applied in cases with concomitant condylar fractures up to 3 weeks. Results. Primary healing of the fractured mandible was observed in all patients. Postoperative complications were minor and transient. The outcome of the operations was not endangered. Adverse tissue reactions to the implants, malocclusion, and growth restrictions did not occur during the observation period. Conclusions. Pediatric patients benefit from the advantages of resorbable materials, especially from faster mobilization and the avoidance of secondary removal operations. Based on these preliminary results, self-reinforced fixation devices are safe and efficient in the treatment of pediatric mandible fractures. However, further clinical investigations are necessary to evaluate the long-term reliability. (Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2005;100:17-24)
In contemporary maxillofacial surgery, biodegradable bone fixation is becoming an alternative treatment in trauma, orthognathic, and craniofacial surgery.1-25 The fast development of new biodegradable materials expands the application to areas where a few years ago only the rigid fixation by metallic plates and screws was possible. New biomechanical properties of biodegradable devices lead to a growing number of indications and even high load-bearing areas such as the human mandible can be treated with these new devices under certain circumstances.8,13-17,21-24 The main advantage of internal resorbable fixation of fractures is the gradual transfer of load to the healing bone during resorption and the elimination of any secondary operation for implant removal, which is common with metallic implants. The clinical realization a
Resident, University Hospital of Cranio-Maxillofacial and Oral Surgery, Medical University of Vienna, Austria. b Resident, Clinic of Dentistry, Medical University of Vienna. c Assistant Professor, University Hospital of Cranio-Maxillofacial and Oral Surgery, Medical University of Vienna. d Professor and Head, University Hospital of Cranio-Maxillofacial and Oral Surgery, Medical University of Vienna. Received for publication Jul 11, 2004; returned for revision Oct 6, 2004; accepted for publication Nov 19, 2004. Available online 12 March 2005. 1079-2104/$ - see front matter Ó 2005 Elsevier Inc. All rights reserved. doi:10.1016/j.tripleo.2004.11.013
of these advantages has increased the interest in developing biodegradable implants, and clinical studies report on the successful use of these devices in pediatric craniofacial surgery.10,11,19,20,25 Maxillofacial fractures are less common in children than in adults. The incidence ranges from approximately 1% in children under the age of 5 years up to 8% in children younger than 12 years of age.26-29 Mandibular fractures are reported to belong to the most frequent facial fractures in pediatric patients.28 The conservative approach in the treatment of maxillofacial trauma in children was common for many reasons. The presence of tooth buds and the elasticity of the pediatric bone were factors for splinting and/or intermaxillary fixation as a standard treatment of mandibular fractures in children during deciduous dentition. Open reduction and internal fixation were avoided in most cases so as not to harm the teeth. The development of microplates and miniplates made it possible to apply these fixation materials in pediatric traumatology as well. This technology offers improved initial stability but its appliance in children is limited in the mandible not only due to the abovementioned reasons but also due to concerns over growth restrictions, stress shielding, corrosion, and palpability. Resorbable osteofixation materials promise to overcome these problems. This clinical study analyzes stability and efficiency of biodegradable self-reinforced bone plates and screws in 17
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18 Yerit et al Table I. Patient data Patient 1 2 3 4 5 6 7 8 9 10 11 12 13
Gender
Age, y
Follow-up, mo
Fracture site (1 not operated)
F M M F F M M F M M M F M
13.1 11.5 13.2 14.6 9.6 13.9 12.3 15.3 16.0 15.8 6.7 9.7 5.0
43.4 42.8 42.7 34.1 31.2 27.0 26.8 26.8 22.0 12.3 11.7 11.1 10.9
body 1 ramus parasymphyseal (1 condyles) Parasymphyseal parasymphyseal 1 body Condyle parasymphyseal (1 condyle) parasymphyseal 1 angle Angle Body parasymphyseal 1 angle symphysis (1 condyles) Condyle symphysis 1 body
Intermaxillary fixation, wk no yes, no no yes, yes, no no no no yes, yes, no
3
2 3
2 2
F, Female; M, male; y, years; mo, months; wk, weeks.
internal fixation of mandibular fractures in a pediatric patient population. PATIENTS AND METHODS Data were collected of 13 patients (Table I) who underwent open reduction and internal fixation with biodegradable self-reinforced (SR-) polyisomers of Dand L-lactic acid with 30% D-lactide and 70% L-lactide (SR-PLDLA) (BioSorb FX, Linvatec Corp, Largo, Fla) during the period from June 2000 to May 2004. Five patients were female and 8 were male. The mean age was 12 years (range 5-16 years) at the time of surgery. Eighteen fractures (2 symphyseal, 6 parasymphyseal, 4 body, 3 angle, 1 ramus, 2 condylar) were fixed internally. Exclusion criteria were surgical treatment initiated more than 3 days after injury, the presence of active infection, and systemic disease. The operation technique was the same for most patients. After access and identification of the fracture, fixation of the bone segments was obtained through the appliance of 2 biodegradable plates. In very young patients, 1 single plate was used to fix the fracture ends such as in patient nos. 5, 11, 12, and 13. The fracture ends were anatomically reduced and fixed with clamps while the mandible was in strong occlusion with the maxilla. The plates were adapted to the bone surface and then holes for the insertion of the screws were drilled. After tapping with a special tap and flushing of the hole, the screws were inserted. Fracture fixation had to be altered in special cases because of anatomical reasons. Patient no. 13 (Fig 1 and Fig 2) is a case that justified an alteration of the treatment: the mandible of this 5-year-old boy was fixed with a single resorbable 6-hole plate at the most inferior border of the symphysis and a 6-hole microplate was applied cranially without harming the tooth buds. This microplate was removed 4 months postoperatively after initial healing of the mandible. The resorbable plate was
left in situ. The fracture of the mandibular body was also reduced and fixed with a single 6-hole plate. Also, in 2 other cases of a fractured and dislocated condyle (patient nos. 5 and 12), the fracture was fixed with 1 single 5-hole plate from a preauricular approach (Fig 3 and Fig 4). Maxillomandibular fixation was applied for 2 weeks following physical therapy. Wound closure was achieved with nonresorbable suture material. Postoperative intermaxillary fixation (IMF) was applied in patients with concomitant condylar fractures. In these cases, IMF was maintained for 2 weeks if the condyles were also operated on, and for 3 weeks if not. All patients were treated with routine antibiotic prophylaxis consisting of penicillin, clindamycin, or cephalosporin for 10 days postoperatively. Appropriate analgesics were also prescribed. All patients were maintained on a strict soft chew diet for 14 days and gradually advanced as tolerated. The routine follow-up consisted of clinical and radiological controls (panoramic radiograph, cephalogram) immediately postoperatively and in 4-, 8-, 12-, and 24-week intervals and thereafter in 6-month intervals. Reduction, stability, displacement, diastasis, and visibility of the fracture line and drill channels and ossification of the mandibular fracture were observed carefully. Patients were also monitored for eventual clinical signs of nonhealing of soft and hard tissue, such as inflammation, formation of fistula, and disturbances of occlusion and sensibility. RESULTS All fractures were united. The mean follow-up time was 26.4 months (range 10.9-43.4 months). In all cases, the self-reinforced fixation system provided satisfactory stability to enable bone healing during the initial phase. No complications occurred during the follow-up period. Initial healing of soft and hard tissue was uneventful in
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Fig 1. Panoramic radiograph of a 5-year-old boy (patient no. 23) fixed with resorbable plates at the symphysis and right mandibular body. The microplate in the symphyseal region is visible before removal after 4 months of bone healing. The resorbable plates are radiolucent and not visible.
Fig 2. Same boy after more than 10 months postoperatively. The microplate has been removed and the mandible shows normal bone healing.
all patients. In 4 cases hypesthesia of the lower lip was observable up to 3 months postoperatively. Thereafter no disturbances of sensibility were observed. The postoperative follow-up was not endangered by infection, exposition of implant material, diastasis, or nonunion. The routine radiographic controls showed
good bone healing without any signs of instability of the fixation. The ossification and restoration of the fractured mandibular bone without any complications could be monitored in the panoramic radiographs. The drill holes for the insertion of the screws, however, were visible in all radiographs as radiolucent areas in all patients
20 Yerit et al
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Fig 3. Intraoperative view shows the insertion of a resorbable screw for the fixation of an SR-PLDLA plate after the reduction of the condylar fracture in patient no. 12.
Fig 4. Intraoperative situation after reduction and fixation of the condylar fracture with resorbable plating system.
through the entire follow-up period (Fig 5 and Fig 6). During the follow-up, no evidence of malocclusion or growth restrictions was observed.
tion, resorption, and elimination from the body. The good tissue acceptance enables a normal healing pattern of the bone. Avoidance of secondary implant removal operations and therefore reduction of overall costs are advantages for the patient with emphasis on the pediatric patient. The amount of trauma is reduced, not only physical but psychological as well. The clinical application of resorbable polymers has been proved in numerous studies. Various materials, such as polylactic acid (PLA), polyglycolic acid (PGA), and polydioxanone (PDS) and their copolymers, are commercially available currently. Besides the applied SR-PLDLA, copolymers of lactic and polyglycolic acid have to be mentioned among many other materials, like the copolymer (PLGA) consisting of 82% PLLA and 18% PGA that is commercially available as Lactosorb (Walter Lorenz Surgical, Jacksonville, Fla) and Biosorb PDX (Linvatec Corp), a blend consisting of 80% PLLA and 20 % PGA. This material is especially recommended for children because of faster resorption and less risk of growth impairment for the fast-growing skeleton.39 PDS is used mainly as suture material but also as pins and screws. The strength of biodegradable materials is usually achieved by the production of bulky and large devices to provide adequate mechanical stability. The development of the self-reinforcing (SR) manufacturing technique40 allowed the production of biodegradable implants with higher strength and with durability and biocompatibility enabling undisturbed bone healing. Biomechanical properties of fixation plates and screws can be improved by this technique. These plates and screws show higher mechanical strength in spite of smaller sizes by the reinforcement of the polymer matrix with elements of the same material in orientation of the axis. In contrast to other resorbable devices, cold bending without heating is possible. These selfreinforced biodegradable bone plates and screws
DISCUSSION Craniomaxillofacial surgery has undergone great progress with the development of conventional titanium plates and screws for osteofixation. However, osteofixation with these metal devices is sometimes associated with drawbacks.30-38 Some patients develop allergic reactions to the metal, which can cause inflammation and the need for removal of the metal. Protruding screws and plates under the skin can be irritating and may be painful. Stress shielding, especially after rigid plate fixation, has been reported and may be a cause for weakening of bone after the removal of the implant. Corrosion and release of metal ions can be a reason to remove the osteofixation devices. In most cases, especially in pediatric patients, this is associated with hospitalization and an increased burden on the health care system. Metal fixation can also cause growth disturbances and it is therefore recommended to remove metallic devices in infants as early as possible after healing of the bone. The use of resorbable materials in treatment of craniosynostosis in the growing infant also avoids a translocation of the material endocranially, which is seen with metallic devices through the natural growth of the infant skull. The material is resorbed before its translocation. Other possible risks would include the interference with imaging techniques such as computed tomography scanning and magnetic resonance imaging or with postoperative radiotherapy. Biodegradable materials do not interfere with radiodiagnostic techniques because of their radiolucency. All the mentioned risks of metal fixation devices can be avoided by the application of resorbable materials. They promise initial strength followed by eventual degrada-
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Fig 5. This panoramic radiograph of patient no. 1 shows the fracture after internal fixation with 2 resorbable 6-hole plates at the right parasymphyseal region 1 month postoperatively. The fracture line and the screw holes are visible.
promise suitable strength and adequate stability for fracture fixation in even high-load fracture sites like the mandible.16,22-24 Nevertheless, adverse effects have also been reported on the use of biodegradable materials. The degradation products of pure PGA or PLA may cause inflammatory reactions as described by studies of Bo¨stman et al41 and Bo¨stman.42 Bergsma et al43 found high crystalline remnants of degradation products in a patient group operated on zygomatic fractures. The sterile abscesses in the operation area had occurred about 3 years after operation. Compared to pure PLLA, the copolymer PLDLA as used in this study and consisting of 30% D-lactide and 70% L-lactide isomers promises a shorter resorption time of 2 to 3 years. No clinical complications have been reported with this material so far. Several clinical studies report on the use of biodegradable materials in pediatric craniofacial surgery. Eppley et al11 used a copolymer of PLLA/PGA for the reconstruction of pediatric craniofacial deformities in 100 patients between 4 and 15 months of age over a period of 2.5 years. The authors concluded that the material was safe and effective for use in pediatric craniofacial application. Kurpad et al19 described their experiences with the use of a polymeric biodegradable system for the correction of congenital pediatric craniofacial malformations in 15 cases. No complications were observed and the authors concluded that the
results of their study supported the use of resorbable fixation systems in the correction of congenital craniofacial deformities. Serlo et al20 used SR-plates and screws for the fixation in cranioplasties in children without any complications in the early follow-up period of 6 months. In 2004, Cohen et al25 performed resorbable osteofixation for reconstruction in pediatric surgical procedures including craniosynostoses, fibrous dysplasia, cranial defects, and encephaloceles. All patients experienced maintenance of stable bone fixation followed by bone healing and the material used was concluded as effective in such indications. With the introduction of the self-reinforcement technique,40 the manufacturing of suitable plates and screws with sufficient stability and rigidity for the treatment of fractures in even high-stress areas seems to be possible. These devices also have the potential to alter and improve the treatment of pediatric trauma. Major advantages of rigid mandible fixation with these devices compared to conservative nonoperative treatment are avoidance or shorter intermaxillary fixation and a fast mobilization of the temporomandibular joint. The overall patient comfort is beneficial especially in the pediatric patient. Nutrition is possible or impaired only for a short time. The clinical application of resorbable osteofixation devices in the mandibular region is reported in a limited number of studies. Experiences in pediatric patients are rare. Due to the lower strength
22 Yerit et al
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Fig 6. Almost 4 years after resorbable fixation in patient no.1. The consolidated mandible does not show any signs of traumatic injury, only some visible screw holes at the inferior border of the mandible may indicate a fracture history of this patient.
of the resorbable materials compared to conventional metal osteofixation systems it was not possible to apply them on mandibular fractures. With the self-reinforcing technique, the strength of plates and screws could be improved and the osteofixation of even high-load sites is reported now by several authors. In a report by Turvey et al,21 good results were achieved in the stabilization of mandibular and maxillary osteotomies. The authors concluded that self-reinforced PLDLA was a reliable fixation material in orthognathic osteotomies as it was proven successfully also by several other study groups.8,13-15,17,21 No serious complications were reported in any of these studies and long-term stability was comparable to clinical reports on metallic devices. In craniofacial traumatology, a study of Kallela et al16 was one of the first to report on lag screw fixation in 11 patients without IMF. Healing was also uneventful in this study. In 2002, Kim and Kim22 published a study about biodegradable fixation of mandibular fractures in 49 patients. In symphysis fractures, 2 plates were used, whereas in body and angle fractures, 1 single plate. Six patients experienced complications such as infection, premature occlusal contact, and temporomandibular disorder. Osteomyelitis occurred in 1 patient 4 months after surgery. In most cases, IMF was applied up to 23 days. Yerit et al23 reported about 22 patients with various fractures of the mandible followed up for an average of 49.1 weeks (22-78 weeks) after internal fixation
with SR-PLDLA plates and screws. They used 2 plates to stabilize fractures of the symphysis, body, angle, and the condyles of the mandible. Mucosal exposure of the plates occurred in 2 cases. The healing pattern of all other fractures was uneventful. Ylikontiola et al24 concluded in a pilot study with 10 patients that SRPLDLA plates and screws were reliable for internal fixation of anterior parasymphyseal mandibular fractures. In 4 cases with concomitant condylar fractures, IMF was applied for 3 weeks. One case of plate exposure resulting in minor infection was observed. The other patients displayed no evidence of disturbances in bone and soft tissue healing. The presence of tooth buds during deciduous dentition in children complicates the appliance of fixation plates in the treatment of mandibular fractures. In our patient group, 4 children were in the early deciduous dentition and none were infants. The standard fracture treatment for adults, the internal osteofixation with plates and screws, is either not an option or only possible in children whose teeth are safely away from the positioning areas. In general, plate fixation will be possible in the symphyseal and parasymphyseal region where screws will not endanger the teeth after the eruption of the incisors and the canines. The inferior border of the mandible is the best place for the positioning of a plate in these fracture sites. Angular fractures together with fractures of the ramus and the
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condyles can be internally fixed with miniplates or microplates, whereas the body of the mandible remains a complicated operation site due to close tooth buds in young children. In older children the application of fixation plates is no problem, but the treatment of younger children is still a demanding procedure. Due to the small and vulnerable anatomy, a single plate is considered to fulfill the requirements of a stable fixation in very young patients. Single plates were used in 4 patients (Table I: patient nos. 5, 11, 12, and 13) due to the early deciduous dentition and fragile anatomy; all other patients were treated with 2 plates at each fracture site. Sometimes the modality of treatment had to be modified and adapted to the individual situation to achieve best results as in patient no. 13 (Fig 1 and Fig 2). The stability of single plates was high enough to enable stable fixation and primary bone healing. In this study, we found no short-term growth abnormalities and occurrence of facial asymmetry as documented in pediatric mandibular fractures.44 The preliminary results were promising and complications did not occur. We assume that the resorption of the implants will not endanger mandibular growth. The resorption of the material seems not to influence bone repair and growth. One important reason may be the soft bone of children. It is still remodeling and it has a higher osteogenetic capacity than that of adults. This enables fast and solid bone healing during the immobilization period. Long-term data are not available and further investigations are necessary to report the results, not only concerning degradation and biocompatibility but also further growth and facial symmetry. CONCLUSION While our follow-up period was too short and the patient population is too small to determine the longterm effects of fracture treatment with biodegradable fixation systems, our preliminary impression is favorable. The self-reinforced devices showed sufficient rigidity and stability to enable initial bone healing of the mandible. The stability of the plates and screws was high enough for fracture fixation in this study group. Tissue intolerance, growth restrictions, and occlusal abnormalities were not seen, and occlusal relationship could be restored in all cases. Benefits for children are evident since patient comfort is higher. Advantages of resorbable fixation materials in general and the benefits for the pediatric patient in particular, including the reduction in time for long-term stability, the diminished immobilization period, and elimination of painful procedures for implant removal make biodegradable osteofixation devices an attractive option in pediatric fracture fixation. However, potential problems relating
Yerit et al 23
to resorption and bone growth have to be observed carefully and investigated in further clinical studies. REFERENCES 1. Kulkarni RK, Pani KC, Neumann C, Leonard F. Polylactic acid for surgical implants. Arch Surg 1966;93:839-43. 2. Cutright DE, Hunsuck EE, Beasley JD. Fracture reduction using a biodegradable material, polylactic acid. J Oral Surg 1971;9: 393-7. 3. Getter L, Cutright DE, Bhaskar SN, Augsburg JK. A biodegradable intraosseous appliance in the treatment of mandibular fractures. J Oral Surg 1972;30:344-8. 4. Cutright DE, Hunsuck EE. The repair of fractures of the orbital floor using biodegradable polylactic acid. Oral Surg Oral Med Oral Pathol 1972;33:28-34. 5. Ewers R, Forster H. Resorbable materials for osteosynthesis. An experimental animal study. Dtsch Z Mund Kiefer Gesichtschir 1985;9:196-201. 6. Ewers R, Ha¨rle F. Experimental and clinical results of new advances in the treatment of facial trauma. Plast Reconstr Surg 1985;75:25-31. 7. Bos RR, Boering G, Rozema FR, Leenslag JW. Resorbable poly(L-lactide) plates and screws for the fixation of zygomatic fractures. J Oral Maxillofac Surg 1987;45:751-3. 8. Suuronen R, Laine P, Pohjonen T, Lindqvist C. Sagittal ramus osteotomies fixed with biodegradable screws: a preliminary report. J Oral Maxillofac Surg 1994;52:715-20. 9. Enislidis G, Pichorner S, Kainberger F, Ewers R. Lactosorb panel and screws for repair of large orbital floor defects. J Craniomaxillofac Surg 1997;25:316-21. 10. Eppley BL. Potential for guided bone regeneration and bone graft fixation with resorbable membranes in pediatric craniofacial surgery. J Craniofac Surg 1997;8:127-8. 11. Eppley BL, Sadove AM, Havlik RJ. Resorbable plate fixation in pediatric craniofacial surgery. Plast Reconstr Surg 1997;100: 1-7. 12. Enislidis G, Pichorner S, Lambert F, Wagner A, Kainberger F, Kautzky M, et al. Fixation of zygomatic fractures with a new biodegradable copolymer osteosynthesis system. Preliminary results. Int J Oral Maxillofac Surg 1998;27: 352-5. 13. Haers PE, Sailer HF. Biodegradable self-reinforced poly-L/DLlactide plates and screws in bimaxillary orthognathic surgery: short-term skeletal stability and material related failures. J Craniomaxillofac Surg 1998;26:363-72. 14. Haers PE, Suuronen R, Lindqvist C, Sailer H. Biodegradable polylactide plates and screws in orthognathic surgery: technical note. J Craniomaxillofac Surg 1998;26:87-91. 15. Kallela I, Laine P, Suuronen R, Iizuka T, Pirinen S, Lindqvist C. Skeletal stability following mandibular advancement and rigid fixation with polylactide biodegradable screws. Int J Oral Maxillofac Surg 1998;27:3-8. 16. Kallela I, Iizuka T, Salo A, Lindquist C. Lag-screw fixation of anterior mandibular fractures using biodegradable polylactide screws: a preliminary report. J Oral Maxillofac Surg 1999;57: 113-8. 17. Kallela I, Laine P, Suuronen R, Ranta P, Iizuka T, Lindqvist C. Osteotomy site healing following mandibular sagittal split osteotomy and rigid fixation with polylactide biodegradable screws. Int J Oral Maxillofac Surg 1999;28: 166-70. 18. Eppley BL. A resorbable and rapid method for maxillomandibular fixation in pediatric mandible fractures. J Craniofac Surg 2000;11:236-8. 19. Kurpad SN, Goldstein JA, Cohen AR. Bioresorbable fixation for congenital pediatric craniofacial surgery: a 2-year follow-up. Pediatr Neurosurg 2000;33:306-10. 20. Serlo W, Kaarela OI, Peltoniemi HH, Merikanto J, Ashammakhi NA, Lassila K, et al. Use of self-reinforced polylactide osteosynthesis devices in craniofacial surgery: a long-term
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follow-up study. Scand J Plast Reconstr Surg Hand Surg 2001; 35:285-92. Turvey TA, Bell RB, Tejera TJ, Proffit WR. The use of selfreinforced biodegradable bone plates and screws in orthognathic surgery. J Oral Maxillofac Surg 2002;60:59-65. Kim YK, Kim SG. Treatment of mandible fractures using bioabsorbable plates. Plast Reconstr Surg 2002;110:25-31. Yerit KC, Enislidis G, Schopper C, Turhani D, Wanschitz F, Wagner A, et al. Fixation of mandibular fractures with biodegradable plates and screws. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2002;94:294-300. Ylikontiola L, Sundqvuist K, Sandor GK, To¨rma¨la¨ P, Ashammakhi N. Self-reinforced bioresorbable poly-L/DL-Lactide [SRP(L/DL)LA] 70/30 miniplates and miniscrews are reliable for fixation of anterior mandibular fractures: a pilot study. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2004;97:312-7. Cohen SR, Holmes RE, Meltzer HS, Levy ML, Beckett MZ. Craniofacial reconstruction with a fast resorbing polymer: a 6- to 12-month clinical follow-up review. Neurosurg Focus 2004;16:E12. MacLennan WD. Fractures of the mandible in children under the age of six years. Br J Surg 1956;9:125-8. Rowe NL. Fractures of the facial skeleton in children. J Oral Surg 1968;26:505-15. Kaban LB, Mulliken JB, Murry JE. Facial fractures in children: an analysis of 122 fractures in 109 patients. Plast Reconstr Surg 1977;59:15-20. Posnick JC, Wells M, Pron G. Pediatric facial fractures: evolving patterns of treatment. J Oral Maxillofac Surg 1993;51:836-44. Fiala TG, Novelline RA, Yaremchuk MJ. Comparison of CT imaging artifacts from craniomaxillofacial internal fixation devices. Plast Reconstr Surg 1993;92:1227-32. Schliephake H, Lehmann H, Kunz U, Schmelzeisen R. Ultrastructural findings in soft tissues adjacent to titanium plates used in jaw fracture treatment. Int J Oral Maxillofac Surg 1993; 22:20-5. Rosenberg A, Gratz KW, Sailer HF. Should titanium miniplates be removed after bone healing is complete? Int J Oral Maxillofac Surg 1993;22:185-8. Uhthoff H, Boisvert D, Finnegan M. Cortical porosis under plates. Reaction to unloading or to necrosis? J Bone Joint Surg 1994;76:1507-12. Fiala TG, Page KT, Davis TL, Campbell TA, Rosen BR, Yaremchuk MJ. Comparison of artifact from craniomaxillfacial internal fixation devices: magnetic resonance imaging. Plast Reconstr Surg 1994;93:725-31.
35. Ho¨nig JF, Merten HA, Luhr HG. Passive and active intracranial translocation of osteosynthesis plates in adolescent minipigs. J Craniofac Surg 1995;6:292-8. 36. Papay FA, Hardy S, Morales L, Walker M, Enlow D. ‘‘False’’ migration of rigid fixation appliances in pediatric craniofacial surgery. J Craniofac Surg 1995;6:309-13. 37. Viljanen J, Kinnunen J, Bandestam S, Majola A, Rokkanen P, Torma¨la¨ P. Bone changes after experimental osteotomies fixed with absorbable self-reinforced poly-L-lactide screws or metallic screws studied by plain radiographs, quantitive computed tomography, and magnetic resonance imaging. Biomaterials 1995;16: 1353-8. 38. Jorgenson DS, Mayer MH, Ellenbogen RG, Centeno JA, Johnson FB, Mullick FG, et al. Detection of titanium in human tissues after craniofacial surgery. Plast Reconstr Surg 1997;99: 976-9. 39. Suuronen R, Haers PE, Lindqvist C, Sailer HF. Update on bioresorbable plates in maxillofacial surgery. Facial Plast Surg 1999;15:61-72. 40. To¨rma¨la¨ P. Biodegradable self-reinforced composite materials: manufacturing structure and mechanical properties. Clin Mater 1992;10:29-34. 41. Bo¨stman O, Hirvensalo E, Ma¨kinen J, Rokkanen P. Foreign body reactions to fracture fixation implants of biodegradable synthetic polymers. J Bone Joint Surg (Br) 1990;72:592-6. 42. Bo¨stman O. Intense granulomatous inflammatory lesions associated with absorbable internal fixation devices made of polyglycolide in ankle fractures. Clin Orthop 1992;278:193-9. 43. Bergsma JE, de Bruijn WC, Rozema FR, Bos RR, Boering G. Late degradation tissue response to poly(L-lactide) bone plates and screws. Biomaterials 1995;16:25-31. 44. Lund K. Mandibular growth and remodelling processes after condylar fracture. A longitudinal roentgencephalometric study. Acta Odontol Scand Suppl 1974;32:3-117. Reprint requests: Kaan C. Yerit Medical University of Vienna University Hospital of Cranio-Maxillofical and Oral Surgery Wahringerstrasse 18-20 Vienna 1090 Austria [email protected]
Objective. The aim of this study was to assess the safety and efficiency of biodegradable self-reinforced (SR-PLDLA) bone plates and screws in open reduction and internal fixation of mandible fractures in children.
Study design. Thirteen patients (5 female, 8 male; mean age 12 years, range 5-16 years) were operated on various fractures of the mandible (2 symphyseal, 6 parasymphyseal, 4 body, 3 angle, 1 ramus, 2 condylar fractures). The mean follow-up time was 26.4 months (range 10.9-43.4 months). Intermaxillary fixation was applied in cases with concomitant condylar fractures up to 3 weeks. Results. Primary healing of the fractured mandible was observed in all patients. Postoperative complications were minor and transient. The outcome of the operations was not endangered. Adverse tissue reactions to the implants, malocclusion, and growth restrictions did not occur during the observation period. Conclusions. Pediatric patients benefit from the advantages of resorbable materials, especially from faster mobilization and the avoidance of secondary removal operations. Based on these preliminary results, self-reinforced fixation devices are safe and efficient in the treatment of pediatric mandible fractures. However, further clinical investigations are necessary to evaluate the long-term reliability. (Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2005;100:17-24)
In contemporary maxillofacial surgery, biodegradable bone fixation is becoming an alternative treatment in trauma, orthognathic, and craniofacial surgery.1-25 The fast development of new biodegradable materials expands the application to areas where a few years ago only the rigid fixation by metallic plates and screws was possible. New biomechanical properties of biodegradable devices lead to a growing number of indications and even high load-bearing areas such as the human mandible can be treated with these new devices under certain circumstances.8,13-17,21-24 The main advantage of internal resorbable fixation of fractures is the gradual transfer of load to the healing bone during resorption and the elimination of any secondary operation for implant removal, which is common with metallic implants. The clinical realization a
Resident, University Hospital of Cranio-Maxillofacial and Oral Surgery, Medical University of Vienna, Austria. b Resident, Clinic of Dentistry, Medical University of Vienna. c Assistant Professor, University Hospital of Cranio-Maxillofacial and Oral Surgery, Medical University of Vienna. d Professor and Head, University Hospital of Cranio-Maxillofacial and Oral Surgery, Medical University of Vienna. Received for publication Jul 11, 2004; returned for revision Oct 6, 2004; accepted for publication Nov 19, 2004. Available online 12 March 2005. 1079-2104/$ - see front matter Ó 2005 Elsevier Inc. All rights reserved. doi:10.1016/j.tripleo.2004.11.013
of these advantages has increased the interest in developing biodegradable implants, and clinical studies report on the successful use of these devices in pediatric craniofacial surgery.10,11,19,20,25 Maxillofacial fractures are less common in children than in adults. The incidence ranges from approximately 1% in children under the age of 5 years up to 8% in children younger than 12 years of age.26-29 Mandibular fractures are reported to belong to the most frequent facial fractures in pediatric patients.28 The conservative approach in the treatment of maxillofacial trauma in children was common for many reasons. The presence of tooth buds and the elasticity of the pediatric bone were factors for splinting and/or intermaxillary fixation as a standard treatment of mandibular fractures in children during deciduous dentition. Open reduction and internal fixation were avoided in most cases so as not to harm the teeth. The development of microplates and miniplates made it possible to apply these fixation materials in pediatric traumatology as well. This technology offers improved initial stability but its appliance in children is limited in the mandible not only due to the abovementioned reasons but also due to concerns over growth restrictions, stress shielding, corrosion, and palpability. Resorbable osteofixation materials promise to overcome these problems. This clinical study analyzes stability and efficiency of biodegradable self-reinforced bone plates and screws in 17
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18 Yerit et al Table I. Patient data Patient 1 2 3 4 5 6 7 8 9 10 11 12 13
Gender
Age, y
Follow-up, mo
Fracture site (1 not operated)
F M M F F M M F M M M F M
13.1 11.5 13.2 14.6 9.6 13.9 12.3 15.3 16.0 15.8 6.7 9.7 5.0
43.4 42.8 42.7 34.1 31.2 27.0 26.8 26.8 22.0 12.3 11.7 11.1 10.9
body 1 ramus parasymphyseal (1 condyles) Parasymphyseal parasymphyseal 1 body Condyle parasymphyseal (1 condyle) parasymphyseal 1 angle Angle Body parasymphyseal 1 angle symphysis (1 condyles) Condyle symphysis 1 body
Intermaxillary fixation, wk no yes, no no yes, yes, no no no no yes, yes, no
3
2 3
2 2
F, Female; M, male; y, years; mo, months; wk, weeks.
internal fixation of mandibular fractures in a pediatric patient population. PATIENTS AND METHODS Data were collected of 13 patients (Table I) who underwent open reduction and internal fixation with biodegradable self-reinforced (SR-) polyisomers of Dand L-lactic acid with 30% D-lactide and 70% L-lactide (SR-PLDLA) (BioSorb FX, Linvatec Corp, Largo, Fla) during the period from June 2000 to May 2004. Five patients were female and 8 were male. The mean age was 12 years (range 5-16 years) at the time of surgery. Eighteen fractures (2 symphyseal, 6 parasymphyseal, 4 body, 3 angle, 1 ramus, 2 condylar) were fixed internally. Exclusion criteria were surgical treatment initiated more than 3 days after injury, the presence of active infection, and systemic disease. The operation technique was the same for most patients. After access and identification of the fracture, fixation of the bone segments was obtained through the appliance of 2 biodegradable plates. In very young patients, 1 single plate was used to fix the fracture ends such as in patient nos. 5, 11, 12, and 13. The fracture ends were anatomically reduced and fixed with clamps while the mandible was in strong occlusion with the maxilla. The plates were adapted to the bone surface and then holes for the insertion of the screws were drilled. After tapping with a special tap and flushing of the hole, the screws were inserted. Fracture fixation had to be altered in special cases because of anatomical reasons. Patient no. 13 (Fig 1 and Fig 2) is a case that justified an alteration of the treatment: the mandible of this 5-year-old boy was fixed with a single resorbable 6-hole plate at the most inferior border of the symphysis and a 6-hole microplate was applied cranially without harming the tooth buds. This microplate was removed 4 months postoperatively after initial healing of the mandible. The resorbable plate was
left in situ. The fracture of the mandibular body was also reduced and fixed with a single 6-hole plate. Also, in 2 other cases of a fractured and dislocated condyle (patient nos. 5 and 12), the fracture was fixed with 1 single 5-hole plate from a preauricular approach (Fig 3 and Fig 4). Maxillomandibular fixation was applied for 2 weeks following physical therapy. Wound closure was achieved with nonresorbable suture material. Postoperative intermaxillary fixation (IMF) was applied in patients with concomitant condylar fractures. In these cases, IMF was maintained for 2 weeks if the condyles were also operated on, and for 3 weeks if not. All patients were treated with routine antibiotic prophylaxis consisting of penicillin, clindamycin, or cephalosporin for 10 days postoperatively. Appropriate analgesics were also prescribed. All patients were maintained on a strict soft chew diet for 14 days and gradually advanced as tolerated. The routine follow-up consisted of clinical and radiological controls (panoramic radiograph, cephalogram) immediately postoperatively and in 4-, 8-, 12-, and 24-week intervals and thereafter in 6-month intervals. Reduction, stability, displacement, diastasis, and visibility of the fracture line and drill channels and ossification of the mandibular fracture were observed carefully. Patients were also monitored for eventual clinical signs of nonhealing of soft and hard tissue, such as inflammation, formation of fistula, and disturbances of occlusion and sensibility. RESULTS All fractures were united. The mean follow-up time was 26.4 months (range 10.9-43.4 months). In all cases, the self-reinforced fixation system provided satisfactory stability to enable bone healing during the initial phase. No complications occurred during the follow-up period. Initial healing of soft and hard tissue was uneventful in
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Fig 1. Panoramic radiograph of a 5-year-old boy (patient no. 23) fixed with resorbable plates at the symphysis and right mandibular body. The microplate in the symphyseal region is visible before removal after 4 months of bone healing. The resorbable plates are radiolucent and not visible.
Fig 2. Same boy after more than 10 months postoperatively. The microplate has been removed and the mandible shows normal bone healing.
all patients. In 4 cases hypesthesia of the lower lip was observable up to 3 months postoperatively. Thereafter no disturbances of sensibility were observed. The postoperative follow-up was not endangered by infection, exposition of implant material, diastasis, or nonunion. The routine radiographic controls showed
good bone healing without any signs of instability of the fixation. The ossification and restoration of the fractured mandibular bone without any complications could be monitored in the panoramic radiographs. The drill holes for the insertion of the screws, however, were visible in all radiographs as radiolucent areas in all patients
20 Yerit et al
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Fig 3. Intraoperative view shows the insertion of a resorbable screw for the fixation of an SR-PLDLA plate after the reduction of the condylar fracture in patient no. 12.
Fig 4. Intraoperative situation after reduction and fixation of the condylar fracture with resorbable plating system.
through the entire follow-up period (Fig 5 and Fig 6). During the follow-up, no evidence of malocclusion or growth restrictions was observed.
tion, resorption, and elimination from the body. The good tissue acceptance enables a normal healing pattern of the bone. Avoidance of secondary implant removal operations and therefore reduction of overall costs are advantages for the patient with emphasis on the pediatric patient. The amount of trauma is reduced, not only physical but psychological as well. The clinical application of resorbable polymers has been proved in numerous studies. Various materials, such as polylactic acid (PLA), polyglycolic acid (PGA), and polydioxanone (PDS) and their copolymers, are commercially available currently. Besides the applied SR-PLDLA, copolymers of lactic and polyglycolic acid have to be mentioned among many other materials, like the copolymer (PLGA) consisting of 82% PLLA and 18% PGA that is commercially available as Lactosorb (Walter Lorenz Surgical, Jacksonville, Fla) and Biosorb PDX (Linvatec Corp), a blend consisting of 80% PLLA and 20 % PGA. This material is especially recommended for children because of faster resorption and less risk of growth impairment for the fast-growing skeleton.39 PDS is used mainly as suture material but also as pins and screws. The strength of biodegradable materials is usually achieved by the production of bulky and large devices to provide adequate mechanical stability. The development of the self-reinforcing (SR) manufacturing technique40 allowed the production of biodegradable implants with higher strength and with durability and biocompatibility enabling undisturbed bone healing. Biomechanical properties of fixation plates and screws can be improved by this technique. These plates and screws show higher mechanical strength in spite of smaller sizes by the reinforcement of the polymer matrix with elements of the same material in orientation of the axis. In contrast to other resorbable devices, cold bending without heating is possible. These selfreinforced biodegradable bone plates and screws
DISCUSSION Craniomaxillofacial surgery has undergone great progress with the development of conventional titanium plates and screws for osteofixation. However, osteofixation with these metal devices is sometimes associated with drawbacks.30-38 Some patients develop allergic reactions to the metal, which can cause inflammation and the need for removal of the metal. Protruding screws and plates under the skin can be irritating and may be painful. Stress shielding, especially after rigid plate fixation, has been reported and may be a cause for weakening of bone after the removal of the implant. Corrosion and release of metal ions can be a reason to remove the osteofixation devices. In most cases, especially in pediatric patients, this is associated with hospitalization and an increased burden on the health care system. Metal fixation can also cause growth disturbances and it is therefore recommended to remove metallic devices in infants as early as possible after healing of the bone. The use of resorbable materials in treatment of craniosynostosis in the growing infant also avoids a translocation of the material endocranially, which is seen with metallic devices through the natural growth of the infant skull. The material is resorbed before its translocation. Other possible risks would include the interference with imaging techniques such as computed tomography scanning and magnetic resonance imaging or with postoperative radiotherapy. Biodegradable materials do not interfere with radiodiagnostic techniques because of their radiolucency. All the mentioned risks of metal fixation devices can be avoided by the application of resorbable materials. They promise initial strength followed by eventual degrada-
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Yerit et al 21
Fig 5. This panoramic radiograph of patient no. 1 shows the fracture after internal fixation with 2 resorbable 6-hole plates at the right parasymphyseal region 1 month postoperatively. The fracture line and the screw holes are visible.
promise suitable strength and adequate stability for fracture fixation in even high-load fracture sites like the mandible.16,22-24 Nevertheless, adverse effects have also been reported on the use of biodegradable materials. The degradation products of pure PGA or PLA may cause inflammatory reactions as described by studies of Bo¨stman et al41 and Bo¨stman.42 Bergsma et al43 found high crystalline remnants of degradation products in a patient group operated on zygomatic fractures. The sterile abscesses in the operation area had occurred about 3 years after operation. Compared to pure PLLA, the copolymer PLDLA as used in this study and consisting of 30% D-lactide and 70% L-lactide isomers promises a shorter resorption time of 2 to 3 years. No clinical complications have been reported with this material so far. Several clinical studies report on the use of biodegradable materials in pediatric craniofacial surgery. Eppley et al11 used a copolymer of PLLA/PGA for the reconstruction of pediatric craniofacial deformities in 100 patients between 4 and 15 months of age over a period of 2.5 years. The authors concluded that the material was safe and effective for use in pediatric craniofacial application. Kurpad et al19 described their experiences with the use of a polymeric biodegradable system for the correction of congenital pediatric craniofacial malformations in 15 cases. No complications were observed and the authors concluded that the
results of their study supported the use of resorbable fixation systems in the correction of congenital craniofacial deformities. Serlo et al20 used SR-plates and screws for the fixation in cranioplasties in children without any complications in the early follow-up period of 6 months. In 2004, Cohen et al25 performed resorbable osteofixation for reconstruction in pediatric surgical procedures including craniosynostoses, fibrous dysplasia, cranial defects, and encephaloceles. All patients experienced maintenance of stable bone fixation followed by bone healing and the material used was concluded as effective in such indications. With the introduction of the self-reinforcement technique,40 the manufacturing of suitable plates and screws with sufficient stability and rigidity for the treatment of fractures in even high-stress areas seems to be possible. These devices also have the potential to alter and improve the treatment of pediatric trauma. Major advantages of rigid mandible fixation with these devices compared to conservative nonoperative treatment are avoidance or shorter intermaxillary fixation and a fast mobilization of the temporomandibular joint. The overall patient comfort is beneficial especially in the pediatric patient. Nutrition is possible or impaired only for a short time. The clinical application of resorbable osteofixation devices in the mandibular region is reported in a limited number of studies. Experiences in pediatric patients are rare. Due to the lower strength
22 Yerit et al
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Fig 6. Almost 4 years after resorbable fixation in patient no.1. The consolidated mandible does not show any signs of traumatic injury, only some visible screw holes at the inferior border of the mandible may indicate a fracture history of this patient.
of the resorbable materials compared to conventional metal osteofixation systems it was not possible to apply them on mandibular fractures. With the self-reinforcing technique, the strength of plates and screws could be improved and the osteofixation of even high-load sites is reported now by several authors. In a report by Turvey et al,21 good results were achieved in the stabilization of mandibular and maxillary osteotomies. The authors concluded that self-reinforced PLDLA was a reliable fixation material in orthognathic osteotomies as it was proven successfully also by several other study groups.8,13-15,17,21 No serious complications were reported in any of these studies and long-term stability was comparable to clinical reports on metallic devices. In craniofacial traumatology, a study of Kallela et al16 was one of the first to report on lag screw fixation in 11 patients without IMF. Healing was also uneventful in this study. In 2002, Kim and Kim22 published a study about biodegradable fixation of mandibular fractures in 49 patients. In symphysis fractures, 2 plates were used, whereas in body and angle fractures, 1 single plate. Six patients experienced complications such as infection, premature occlusal contact, and temporomandibular disorder. Osteomyelitis occurred in 1 patient 4 months after surgery. In most cases, IMF was applied up to 23 days. Yerit et al23 reported about 22 patients with various fractures of the mandible followed up for an average of 49.1 weeks (22-78 weeks) after internal fixation
with SR-PLDLA plates and screws. They used 2 plates to stabilize fractures of the symphysis, body, angle, and the condyles of the mandible. Mucosal exposure of the plates occurred in 2 cases. The healing pattern of all other fractures was uneventful. Ylikontiola et al24 concluded in a pilot study with 10 patients that SRPLDLA plates and screws were reliable for internal fixation of anterior parasymphyseal mandibular fractures. In 4 cases with concomitant condylar fractures, IMF was applied for 3 weeks. One case of plate exposure resulting in minor infection was observed. The other patients displayed no evidence of disturbances in bone and soft tissue healing. The presence of tooth buds during deciduous dentition in children complicates the appliance of fixation plates in the treatment of mandibular fractures. In our patient group, 4 children were in the early deciduous dentition and none were infants. The standard fracture treatment for adults, the internal osteofixation with plates and screws, is either not an option or only possible in children whose teeth are safely away from the positioning areas. In general, plate fixation will be possible in the symphyseal and parasymphyseal region where screws will not endanger the teeth after the eruption of the incisors and the canines. The inferior border of the mandible is the best place for the positioning of a plate in these fracture sites. Angular fractures together with fractures of the ramus and the
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condyles can be internally fixed with miniplates or microplates, whereas the body of the mandible remains a complicated operation site due to close tooth buds in young children. In older children the application of fixation plates is no problem, but the treatment of younger children is still a demanding procedure. Due to the small and vulnerable anatomy, a single plate is considered to fulfill the requirements of a stable fixation in very young patients. Single plates were used in 4 patients (Table I: patient nos. 5, 11, 12, and 13) due to the early deciduous dentition and fragile anatomy; all other patients were treated with 2 plates at each fracture site. Sometimes the modality of treatment had to be modified and adapted to the individual situation to achieve best results as in patient no. 13 (Fig 1 and Fig 2). The stability of single plates was high enough to enable stable fixation and primary bone healing. In this study, we found no short-term growth abnormalities and occurrence of facial asymmetry as documented in pediatric mandibular fractures.44 The preliminary results were promising and complications did not occur. We assume that the resorption of the implants will not endanger mandibular growth. The resorption of the material seems not to influence bone repair and growth. One important reason may be the soft bone of children. It is still remodeling and it has a higher osteogenetic capacity than that of adults. This enables fast and solid bone healing during the immobilization period. Long-term data are not available and further investigations are necessary to report the results, not only concerning degradation and biocompatibility but also further growth and facial symmetry. CONCLUSION While our follow-up period was too short and the patient population is too small to determine the longterm effects of fracture treatment with biodegradable fixation systems, our preliminary impression is favorable. The self-reinforced devices showed sufficient rigidity and stability to enable initial bone healing of the mandible. The stability of the plates and screws was high enough for fracture fixation in this study group. Tissue intolerance, growth restrictions, and occlusal abnormalities were not seen, and occlusal relationship could be restored in all cases. Benefits for children are evident since patient comfort is higher. Advantages of resorbable fixation materials in general and the benefits for the pediatric patient in particular, including the reduction in time for long-term stability, the diminished immobilization period, and elimination of painful procedures for implant removal make biodegradable osteofixation devices an attractive option in pediatric fracture fixation. However, potential problems relating
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