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Pediatric facial fractures: Evolving patterns of treatment
Oral Abstract SessionII: Facial Pathology and Trauma Management
A Comparison of theAccuracyof lkro Methods for Inserting Lug Screws Peter Ilg, DDS, Div. of OMS, Univ. of Texas Southwest Med. Cntr., 5323 Harry Hines Blvd, Dallas, TX 75235 (Ellis, E.) Use of the lag screw technique is becoming more popular in maxillofacial surgery. There are two different systems by which a lag screw can be inserted. In order to verify the accuracy of both methods and compare them, the following experimental investigation was performed. The techniques of lag screw insertion as advocated by the A0 (Synthes) system and the Howmedica (Luhr) system were used for this study. In the A0 system, a 2.7 mm diameter drill is first drilled through the outer cortex. A drill guide which centers a 2.0 mm drill is then inserted, and the inner cortex is drilled. The outer cortex is countersunk with a special countersinking tool prior to screw insertion. The Luhr system uses a 2.1 mm drill which is initially drilled through both cortical plates. A special instrument (drill) is then used to overdrill and countersink the outer cortex at the same time. To simulate cortical bone, 48 pairs of nylon discs with a thickness of ‘/ inch and a diameter of 2 inches were prepared on a lathe. The top disc of each pair represented the external cortex and the bottom disc represented the inner cortex. Twenty four discs were perforated with a 2.7 mm drill and the other 24 discs were perforated with a 2.1 mm drill. A lathe was used in order to begin the experiment with perfect centering of the holes in the outer cortex. To maintain perfect concentricity of the outer and inner discs while drilling the inner cortex, a guide was used to align them. Using the hole in the outer disc as a guide, the inner disc was drilled using the two techniques. The distance between the outer and inner discs was controlled by insertion of 0,5, and 10 mm Styrofoam spacers. The minimal distance between the edge of the drilled holes and the border of the disc was measured with a digital caliper with 0.01 mm precision. For the Luhr system, the outer cortices were overdrilled using the recommended drill. These discs were again measured and compared to the 2.7 mm values from the lathe-drilled cortices. Lastly, the discs were countersunk using the manufacturer’s instruments and screws were inserted. The discs were rotated until maximum eccentricity was produced and the amount quantified. Each measurement was made 3 times on different days--the measures were averaged prior to statistical analysis. This also allowed calculation of the error of the method. The data for the two groups and for the different spacers was analyzed using t-tests. There was a significant difference in the ability of the two systems to drill a concentric hole through the inner cortex with the 5 mm spacers (p = 0.003) but not with the 0 and 10 mm spacers. When compared to the lathe 74
drilled holes, overdrilling the outer hole in the Luhr system was found to be very accurate. Following countersinking and insertion of the screws without any spacers, the Luhr system displaced the discs an average of 0.41 mm (sd = 0.21), while the Synthes system displaced the discs an average of 0.20 mm (sd = 0.15) (p < 0.001). When evaluated by the spacer thickness during the drilling process, the Luhr system caused more displacement at the 0 and 5 mm spacers but there was no significant difference when 10 mm spacers were used, probably related to a much higher standard deviation in both groups. The results of this experimental study indicate that the Synthes system is a more accurate method for lag screw insertion, with less displacement of the inner and outer cortices. However the influence of the technique on clinical results is not established. The differences obtained in this experimental model were very small and the clinical significance of them was not addressed. References
Ellis,E., Ghali, G.: Lag screwfixationof mandibular angle fractures. J Oral Maxillofac Surg 49:234,1991 Ellis, E., Ghali, G.: Lag screw fixation of anterior mandibular fractures. J Oral Maxillofac Surg 49:13,1991
PediatricFacial Fractures: EvolvingPatternsof Treatment Jeffrey C. Posnick, DMD, MD, The Hospital for Sick Children, Rm 5430-555, University Ave, Toronto, Ontario, Canada M5G 1X8 (Wells, M., Pron, G.) The purpose of this study is to review the facial trauma experience at a major pediatric referral center in a prospective manner from 1986 to 1990. All patients with a diagnosis of craniomaxillofacial trauma, who were evaluated by the pediatric craniofacial team, were entered into the study. Parameters evaluated included the etiology of the trauma event as well whether they were seen initially at this institution or referred for secondary reconstruction. The location and extent of facial fractures and soft tissue injuries were cataloged as well as the presence of any associated injuries. The nature of the treatment provided and the occurrence of perioperative complications were recorded. The trauma population consisted of 146 subjects who sustained 327 facial fractures. Eighty five patients were seen acutely and 61 patients were referred for secondary management. The average age of the patients was 9.2 years. Males (63%) were more prevalent than females (37%) in the study with the 6 to 12 year cohort, making up the largest group (41%). Traffic related accidents accounted for our largest group of patients (50%) AAOMS
.
1991
Oral Abstract SessionII: Facial Pathology
followed by falls (25%) and sports related injuries (14%). Mandibular fracturespredominated(33%) followed by orbital injuries (22%). A low incidence of midfacialfractures(10%)comparedto the adult population wasnoted. Of the acutely managedpopulation, 175 fractures were noted of which 121were managedsurgically.Sixty two patients underwentopen reduction.The commonest method of stabilizationwasplate and screw.fixation (63%), followedby interosseouswires (16%).Nine bone grafts were required, primarily for orbital injuries, the commonestdonor site beingthe cranium (66%). Unlike adult facial trauma patients, none were required for midfacial buttressreconstruction. There has been a trend towardsthe use of plate and screw fixation when open reduction is indicated. This contrastswith other reportsin the literature which have recommendedminimal exposureandfixation.Perioperativecomplicationratesin the acutelymanagedpatients has remainedlow. Long term affectsof open reduction and this type of fixation on facial growth remain unanswered. References
Kabau, LB., Mulliken, LB., Muny, J.E.: Facial fractures in children: Analysis of 122 fractures in 109 patients. Plast Reconstr Surg 59:15,1977 CarolI, M.J., Hill, M.C., Manson, D.A.: Facial fractures in children. Br Dent J 163:23,1987
ResuiYsofRigidI~F~ofMdti~ F~P~rrsa Laboretoryexetcise Leon A. Assael,DMD, Dept. of OMS, G7073,School of Dental Medicine, Univ. of ConnecticutHealth Center,Farmington,CT 06030 Rigid internal fixation of mandiblefractureshasbeen utilixed as a meansof permitting healing under stable conditionswith immediate function. It is an attractive means of treating fractures becauseit accurately restoresthe preciseanatomicrelationshipspresentbefore injury. By providing fixation forces that exceedfunctional forcesat all times during the courseof healing,it is not necessaryto place the patient into intermaxillary fixation postoperatively.A lower incidenceof infection dueto the absenceof interfragmentarymobility hasalso been reported. While these goals of rigid internal
A&OMS .
1991
andTraumaManagement
appearto be well understood,the demandsof this highly technicalmethod in the clinical situation has resulted in a sign&ant incidenceof techniquerelated failure. The purpose of this laboratory study was to determinethe potential for techniquerelatedfailure. Materials ami Methods: 74 surgeonstaking the AdvancedMaxillofacial Courseof the Associationfor the Studyof Internal Fixation in Davos,Switzerlandin 12/90 weregivena laboratoryexercise.Each surgeonhadused rigid internal fixation of the mandible activelyin clinical practice and had taken a basic course.Surgeonswere: oral and maxillofacial surgeons,otolaryngologistsand plasticsurgeonsfrom 29nations. Each team of two surgeonswas askedto treat identical fractures of a replicated human mandible: a right ramus, right symphyseal,left body and left condyle complex mandible fracture. They were instructed to applyRIF techniquesaccordingto A0 principlessothat immediatefunctiori could occur.Immediatelypreceding this exercise,reviewof thesetechniqueshad takenplace in the didactic portion of the course.A completeset of instrumentsplates and screwswas available for each team, At the conclusionof the 2 hour exercise,each mandiblewasexaminedand photographedby the same observer. Results:Evaluation showedthat of the 148fractures, 121had beentreated.Of these,29 (24%) had methods of treatment that would definitely have resulted in clinical failure during function. The reasonsfor failure include insufficientscrews(lessthan two on one side of the fracture, misplaced screws(i.e. loose screwin the fracture site), mismatchinghardware(i.e. the useof 2.7 screwswith 2.0 plate), and poorly contoured plates (producing gross fracture distraction). Of 637 screws placed43 (7%) would havedamagedthe teeth and 38 (6%) would havelikely damagedthe mandibular nerve. Conclusion:The applicationof rigid internal fixation of mandibular fractures in the laboratory produceda high rate of iatrogenic complications. These include likely mechanicalfailure (24%), tooth injury (7%) and nerve injury (6%). These results imply that failure in techniqueapplicationis an important reasonfor complicationsin rigid internal fixation of mandibularfractures.
fixation
References Assael, L.: Complications of rigid internal fixation of the facial skeleton. Oral Maxillofac Surg Clin North Am 2:615,1990 Spiessl, B.: Internal Fixation of the Mandible, Springer, Berlin, 1989
75
A Comparison of theAccuracyof lkro Methods for Inserting Lug Screws Peter Ilg, DDS, Div. of OMS, Univ. of Texas Southwest Med. Cntr., 5323 Harry Hines Blvd, Dallas, TX 75235 (Ellis, E.) Use of the lag screw technique is becoming more popular in maxillofacial surgery. There are two different systems by which a lag screw can be inserted. In order to verify the accuracy of both methods and compare them, the following experimental investigation was performed. The techniques of lag screw insertion as advocated by the A0 (Synthes) system and the Howmedica (Luhr) system were used for this study. In the A0 system, a 2.7 mm diameter drill is first drilled through the outer cortex. A drill guide which centers a 2.0 mm drill is then inserted, and the inner cortex is drilled. The outer cortex is countersunk with a special countersinking tool prior to screw insertion. The Luhr system uses a 2.1 mm drill which is initially drilled through both cortical plates. A special instrument (drill) is then used to overdrill and countersink the outer cortex at the same time. To simulate cortical bone, 48 pairs of nylon discs with a thickness of ‘/ inch and a diameter of 2 inches were prepared on a lathe. The top disc of each pair represented the external cortex and the bottom disc represented the inner cortex. Twenty four discs were perforated with a 2.7 mm drill and the other 24 discs were perforated with a 2.1 mm drill. A lathe was used in order to begin the experiment with perfect centering of the holes in the outer cortex. To maintain perfect concentricity of the outer and inner discs while drilling the inner cortex, a guide was used to align them. Using the hole in the outer disc as a guide, the inner disc was drilled using the two techniques. The distance between the outer and inner discs was controlled by insertion of 0,5, and 10 mm Styrofoam spacers. The minimal distance between the edge of the drilled holes and the border of the disc was measured with a digital caliper with 0.01 mm precision. For the Luhr system, the outer cortices were overdrilled using the recommended drill. These discs were again measured and compared to the 2.7 mm values from the lathe-drilled cortices. Lastly, the discs were countersunk using the manufacturer’s instruments and screws were inserted. The discs were rotated until maximum eccentricity was produced and the amount quantified. Each measurement was made 3 times on different days--the measures were averaged prior to statistical analysis. This also allowed calculation of the error of the method. The data for the two groups and for the different spacers was analyzed using t-tests. There was a significant difference in the ability of the two systems to drill a concentric hole through the inner cortex with the 5 mm spacers (p = 0.003) but not with the 0 and 10 mm spacers. When compared to the lathe 74
drilled holes, overdrilling the outer hole in the Luhr system was found to be very accurate. Following countersinking and insertion of the screws without any spacers, the Luhr system displaced the discs an average of 0.41 mm (sd = 0.21), while the Synthes system displaced the discs an average of 0.20 mm (sd = 0.15) (p < 0.001). When evaluated by the spacer thickness during the drilling process, the Luhr system caused more displacement at the 0 and 5 mm spacers but there was no significant difference when 10 mm spacers were used, probably related to a much higher standard deviation in both groups. The results of this experimental study indicate that the Synthes system is a more accurate method for lag screw insertion, with less displacement of the inner and outer cortices. However the influence of the technique on clinical results is not established. The differences obtained in this experimental model were very small and the clinical significance of them was not addressed. References
Ellis,E., Ghali, G.: Lag screwfixationof mandibular angle fractures. J Oral Maxillofac Surg 49:234,1991 Ellis, E., Ghali, G.: Lag screw fixation of anterior mandibular fractures. J Oral Maxillofac Surg 49:13,1991
PediatricFacial Fractures: EvolvingPatternsof Treatment Jeffrey C. Posnick, DMD, MD, The Hospital for Sick Children, Rm 5430-555, University Ave, Toronto, Ontario, Canada M5G 1X8 (Wells, M., Pron, G.) The purpose of this study is to review the facial trauma experience at a major pediatric referral center in a prospective manner from 1986 to 1990. All patients with a diagnosis of craniomaxillofacial trauma, who were evaluated by the pediatric craniofacial team, were entered into the study. Parameters evaluated included the etiology of the trauma event as well whether they were seen initially at this institution or referred for secondary reconstruction. The location and extent of facial fractures and soft tissue injuries were cataloged as well as the presence of any associated injuries. The nature of the treatment provided and the occurrence of perioperative complications were recorded. The trauma population consisted of 146 subjects who sustained 327 facial fractures. Eighty five patients were seen acutely and 61 patients were referred for secondary management. The average age of the patients was 9.2 years. Males (63%) were more prevalent than females (37%) in the study with the 6 to 12 year cohort, making up the largest group (41%). Traffic related accidents accounted for our largest group of patients (50%) AAOMS
.
1991
Oral Abstract SessionII: Facial Pathology
followed by falls (25%) and sports related injuries (14%). Mandibular fracturespredominated(33%) followed by orbital injuries (22%). A low incidence of midfacialfractures(10%)comparedto the adult population wasnoted. Of the acutely managedpopulation, 175 fractures were noted of which 121were managedsurgically.Sixty two patients underwentopen reduction.The commonest method of stabilizationwasplate and screw.fixation (63%), followedby interosseouswires (16%).Nine bone grafts were required, primarily for orbital injuries, the commonestdonor site beingthe cranium (66%). Unlike adult facial trauma patients, none were required for midfacial buttressreconstruction. There has been a trend towardsthe use of plate and screw fixation when open reduction is indicated. This contrastswith other reportsin the literature which have recommendedminimal exposureandfixation.Perioperativecomplicationratesin the acutelymanagedpatients has remainedlow. Long term affectsof open reduction and this type of fixation on facial growth remain unanswered. References
Kabau, LB., Mulliken, LB., Muny, J.E.: Facial fractures in children: Analysis of 122 fractures in 109 patients. Plast Reconstr Surg 59:15,1977 CarolI, M.J., Hill, M.C., Manson, D.A.: Facial fractures in children. Br Dent J 163:23,1987
ResuiYsofRigidI~F~ofMdti~ F~P~rrsa Laboretoryexetcise Leon A. Assael,DMD, Dept. of OMS, G7073,School of Dental Medicine, Univ. of ConnecticutHealth Center,Farmington,CT 06030 Rigid internal fixation of mandiblefractureshasbeen utilixed as a meansof permitting healing under stable conditionswith immediate function. It is an attractive means of treating fractures becauseit accurately restoresthe preciseanatomicrelationshipspresentbefore injury. By providing fixation forces that exceedfunctional forcesat all times during the courseof healing,it is not necessaryto place the patient into intermaxillary fixation postoperatively.A lower incidenceof infection dueto the absenceof interfragmentarymobility hasalso been reported. While these goals of rigid internal
A&OMS .
1991
andTraumaManagement
appearto be well understood,the demandsof this highly technicalmethod in the clinical situation has resulted in a sign&ant incidenceof techniquerelated failure. The purpose of this laboratory study was to determinethe potential for techniquerelatedfailure. Materials ami Methods: 74 surgeonstaking the AdvancedMaxillofacial Courseof the Associationfor the Studyof Internal Fixation in Davos,Switzerlandin 12/90 weregivena laboratoryexercise.Each surgeonhadused rigid internal fixation of the mandible activelyin clinical practice and had taken a basic course.Surgeonswere: oral and maxillofacial surgeons,otolaryngologistsand plasticsurgeonsfrom 29nations. Each team of two surgeonswas askedto treat identical fractures of a replicated human mandible: a right ramus, right symphyseal,left body and left condyle complex mandible fracture. They were instructed to applyRIF techniquesaccordingto A0 principlessothat immediatefunctiori could occur.Immediatelypreceding this exercise,reviewof thesetechniqueshad takenplace in the didactic portion of the course.A completeset of instrumentsplates and screwswas available for each team, At the conclusionof the 2 hour exercise,each mandiblewasexaminedand photographedby the same observer. Results:Evaluation showedthat of the 148fractures, 121had beentreated.Of these,29 (24%) had methods of treatment that would definitely have resulted in clinical failure during function. The reasonsfor failure include insufficientscrews(lessthan two on one side of the fracture, misplaced screws(i.e. loose screwin the fracture site), mismatchinghardware(i.e. the useof 2.7 screwswith 2.0 plate), and poorly contoured plates (producing gross fracture distraction). Of 637 screws placed43 (7%) would havedamagedthe teeth and 38 (6%) would havelikely damagedthe mandibular nerve. Conclusion:The applicationof rigid internal fixation of mandibular fractures in the laboratory produceda high rate of iatrogenic complications. These include likely mechanicalfailure (24%), tooth injury (7%) and nerve injury (6%). These results imply that failure in techniqueapplicationis an important reasonfor complicationsin rigid internal fixation of mandibularfractures.
fixation
References Assael, L.: Complications of rigid internal fixation of the facial skeleton. Oral Maxillofac Surg Clin North Am 2:615,1990 Spiessl, B.: Internal Fixation of the Mandible, Springer, Berlin, 1989
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