Internal Fixation of the Mandible

I: Basic Principles.- 1 Goals of the AO/ASIF Technique.- 2 The Stability Principle.- 2.1 Instability and Its Consequences.- 2.2 Experimental Investigations of Stability and Instability.- 2.3 Significance of the Stability Principle.- 2.3.1 Indirect (Secondary) and Direct (Primary) Bone Healing.- 3 Biomechanics.- 3.1 Anatomic Aspects of Biomechanics.- 3.1.1 Form and Structure of the Mandible.- 3.1.2 Muscular Apparatus of the Mandible.- 3.1.3 Implications for the Biomechanics of Internal Fixation.- 3.2 Biomechanics of Fracture Treatment: Experimental Background (B. Rahn).- 3.2.1 Mechanisms of Stabilization.- 3.2.1.1 Stabilization by Splinting.- 3.2.1.2 Stabilization by Compression.- 3.2.2 Special Situation in the Mandible.- 3.2.3 Bone Healing.- 3.2.3.1 Indirect Bone Healing.- 3.2.3.2 Direct Bone Healing.- 3.2.3.3 Plate-Induced Porosis, “Stress Protection”.- 3.2.3.4 Disturbed Healing Process.- 3.2.4 Implant Design.- 4 Principles of the ASIF Technique.- 4.1 Interfragmental Compression for Functionally Stable Internal Fixation.- 4.1.1 Static Compression.- 4.1.1.1 Static Compression with a Prestressed Plate (DCP).- 4.1.1.2 Eccentric Dynamic Compression Plate (EDCP) for Creating Uniform Pressure on the Oral Side.- 4.1.1.3 Overbending the Plate to Improve Compression on the Lingual Side.- 4.1.1.4 Static Compression with a Lag Screw.- 4.1.2 Dynamic Compression.- 4.1.2.1 Application of the Tension Band Principle in the Mandible.- 4.1.2.2 Tension Band Plate and Tension Band Splint.- 4.1.2.3 Experimental Studies of the Tension Band Splint.- 4.1.2.4 Tension Band Plate.- 4.1.2.5 Plate and Tension Band System.- 4.1.2.6 Interfragmental Compression Without a Tension Band.- 4.1.2.7 Applications of the EDCP.- 4.1.2.8 Applications of the Reconstruction Plate.- 4.2 Principle of Surgical Splinting.- 4.2.1 Internal Splinting.- 4.2.1.1 Buttressing.- 4.2.1.2 Bridging.- 4.2.1.3 Internal Bone Splinting Combined with Interfragmental Compression.- 4.2.2 External Splinting: External Fixator.- 4.2.2.1 Principle, Design, and Advantages.- 4.2.2.2 Clinical Significance.- 4.2.2.3 Indications.- 4.2.2.4 Historical Aspects of External Fixation.- 4.2.2.5 Biomechanics of External Fixation.- 4.2.2.6 One-Bar External Fixator.- 4.2.2.7 Indications for External Fixation.- 5 ASIF Instrumentation.- 5.1 Instrument Sets for Mandibular Surgery.- 5.2 Materials.- 5.2.1 Materials for Mandibular Implants.- 5.2.2 Materials for Instruments.- 5.3 Mandibular Instruments.- 5.3.1 Reduction and Compressing Instruments.- 5.3.2 Instruments for Screw Insertion.- 5.3.2.1 Instruments for Direct Screw Insertion.- 5.3.2.2 Instruments for Transbuccal Screw Insertion.- 5.3.2.3 Small Air Drill with Quick Coupling.- 5.3.2.4 Instruments for Bending and Twisting.- 5.4 Mandibular Implants.- 5.4.1 Mandibular Plates.- 5.4.1.1 Linear System: DCP and EDCP.- 5.4.1.2 Universal Plate System: Reconstruction Plate.- 5.4.1.3 Principles of Plate Bending.- 5.4.2 Mandibular Screws.- 5.4.2.1 Cortex Screw.- 5.4.2.2 Emergency Screw.- 5.4.2.3 Technique of Screw Insertion.- 5.4.3 Wire as a Fixation Material.- 5.5 Wire Acrylic Splint (Schuchardt Splint).- 5.5.1 Functions: Reduction, Retention, Tension Band.- 5.5.2 Materials and Instrumentation.- 5.5.3 Splinting Technique.- 5.5.3.1 Placement of the Arch Bar.- 5.5.3.2 Wiring the Arch Bar to the Teeth.- 5.5.3.3 Stiffening the Arch Bar.- 6 Preoperative, Intraoperative, and Postoperative Guidelines.- 6.1 Organizational Requirements.- 6.2 Priorities in the Care of Multiple Trauma Patients.- 6.3 Timing of Operation.- 6.3.1 Plan of Operation.- 6.3.2 Preparation of the Operative Field.- 6.4 Postoperative Care.- 6.5 Atraumatic Operating Technique.- 6.5.1 Handling of the Soft Tissues.- 6.5.1.1 Value of the Scalpel Technique.- 6.5.2 Prevention of Infection.- 6.5.3 Handling of the Bone.- 6.6 Antibiotic Prophylaxis (General).- 6.7 Interaction Between the Implant and Tissue.- 6.7.1 Mechanical Interactions.- 6.7.2 Chemical-Physiologic Interactions.- 6.7.3 Observations in Mandibular Implants.- 6.7.4 Implant Removal.- 6.7.5 Timing of Implant Removal.- 6.7.6 Technique of Implant Removal.- 6.8 Complications.- 6.8.1 Posttraumatic Bone Infection.- 6.8.2 Postoperative Hematoma.- 6.8.3 Postoperative Pain and Inflammatory Edema.- 6.8.4 Postoperative Osteitis.- 6.8.4.1 Definition and Pathogenesis.- 6.8.4.2 Early Infection.- 6.8.4.3 Late Infection.- 6.8.4.4 Summary of Therapeutic Principles.- II: Internal Fixation of Fresh Fractures.- 1 Introduction.- 2 Classification of Fractures.- 2.1 Definition of Fracture.- 2.2 Approaches to Classification.- 2.3 Findings Relevant to Internal Fixation.- 2.4 Classification Scheme.- 2.4.1 Classification of Fractures by the Number of Fragments and the Presence of a Bone Defect (F1-F4).- 2.4.2 Classification of Fractures by Site (L1-L8).- 2.4.3 Classification of Fractures by Displacement (O0-O2).- 2.4.4 Fracture Formula.- 2.4.5 Classification of Fractures by Soft-Tissue Involvement (S0-S4).- 2.4.6 Associated Fractures (A0-A6).- 2.4.7 Summary of the Constituent Findings in Mandibular Fractures and the Fracture Formula.- 2.4.8 Grouping of Open and Closed Fractures by Grades of Severity and Clinical Categories (FS Formula).- 3 Indications for Internal Fixation.- 3.1 Priority of Early Treatment in Multiple Trauma Patients.- 3.2 Sequencing of Priorities in Patients with Life-Threatening Hemorrhage.- 3.3 Early Stabilization in Concomitant Craniocerebral Trauma.- 3.4 Priorities in the Treatment of Concomitant Le Fort and Mandibular Fractures.- 3.5 Parallel Care in Multiple Trauma Patients.- 3.6 Contraindications to Internal Fixation and Exceptions.- 3.7 Absolute Indications.- 3.8 Condylar Neck Fractures: Their Significance as an Indirect Indication for Internal Fixation.- 4 Surgical Approaches.- 4.1 Inadequacy of Unilateral Fracture Treatment.- 4.2 Principle of Combined Fracture Treatment.- 4.3 Anatomic Landmarks for the Extraoral Approaches.- 4.4 Position of the Head.- 4.5 Classification of Approaches.- 4.6 Purpose of a Systematic Technique of Fracture Exposure.- 4.7 Directions of the Incision.- 4.7.1 Closed Fractures.- 4.7.2 Open Fractures.- 4.8 Angle of the Incision.- 4.9 Surgical Anatomy of the Approaches.- 4.9.1 Submandibular Approach.- 4.9.1.1 Sulcus Incision: Incision in the Natural Cervical Crease (Hyoid Sulcus).- 4.9.1.2 Paramandibular Incision.- 4.9.2 Subangular Approach.- 4.9.3 Submental Approach.- 5 Closed Fractures.- 5.1 Definition of Terms.- 5.2 Classification.- 5.3 Single Fracture (F1S0, Grade I).- 5.3.1 Internal Fixation of Transverse and Oblique Fractures in the Precanine Region (Median, Paramedian, and Canine Fractures).- 5.3.1.1 Intraoral Approach: Indication for DCP.- 5.3.1.2 Extraoral Approach: Indication for EDCP.- 5.3.2 Internal Fixation of Transverse and Oblique Fractures in the Postcanine Region (Fractures of the Lateral Mandible).- 5.3.2.1 Extraoral Approach.- 5.3.3 Internal Fixation of Angle Fractures.- 5.3.3.1 Statistics.- 5.3.3.2 Central Angle Fractures.- 5.3.3.3 Peripheral Angle Fractures.- 5.3.3.4 Marginal Angle Fractures.- 5.3.3.5 Rules for Electing the Internal Fixation of Angle Fractures.- 5.3.3.6 Problems Specific to the Mandibular Angle.- 5.3.3.7 Technique of Internal Fixation of the Angle.- 5.3.4 Internal Fixation of Oblique-Surface Fractures.- 5.4 Multiple Fractures (F2S0, Grade II A).- 5.4.1 Internal Fixation of a Double Fracture in the Dentulous Mandible.- 5.4.1.1 Indications.- 5.4.1.2 Techniques of Internal Fixation.- 5.4.2 Internal Fixation of a Double Fracture in the Edentulous Mandible.- 5.4.2.1 Indications.- 5.4.2.2 Techniques of Internal Fixation.- 5.4.3 Unilateral Segmental Fracture.- 5.4.4 Unilateral Segmental Fracture and Contralateral Single Fracture.- 5.5 Comminuted Fractures (F3 S0).- 6 Open Fractures.- 6.1 Definition of Terms.- 6.2 Classification.- 6.3 Statistics.- 6.4 Wound Treatment and Splinting in Preparation for Definitive Stabilization of the Fracture.- 6.4.1 Emergency Treatment.- 6.4.2 Preoperative Preparation.- 6.4.3 Intraoral Wound Care and Splinting.- 6.4.4 Extraoral Wound Treatment and Debridement.- 6.5 Internal Fixation of the Open Fracture.- 6.5.1 Indications for Bone Plating.- 6.5.2 Indications for External Fixation.- 6.6 Antibiotic Prophylaxis.- 6.7 Illustrative Case Reports.- 6.8 Gunshot Fractures.- 7 Treatment of Mandibular Fractures in Children.- III: Reconstructive Surgery.- 1 Introduction.- 2 Nonunion.- 2.1 Causes.- 2.2 Classification.- 2.3 Clinical Aspects and Treatment of Noninfected Nonunions.- 2.4 Clinical Aspects and Treatment of Nonreactive, Avascular Nonunions.- 2.5 Clinical Aspects and Treatment of Infected Nonunions.- 2.5.1 Previously Infected Nonunion.- 2.5.2 Infected, Draining Nonunion.- 3 Reconstruction of Segmental Defects in Tumor Surgery.- 3.1 Introduction to the Problem.- 3.2 Technical Principles.- 3.2.1 Bridging Without an Autogenous Bone Graft.- 3.2.1.1 THRP or Reconstruction Plate for Definitive Reconstruction.- 3.2.1.2 Bridging as Definitive Treatment for Mandibular Metastases.- 3.2.1.3 Reconstruction Plate for Interim Bridging.- 3.2.1.4 Covering Soft-Tissue Defects and Bridging Segmental Defects.- 3.2.2 Bridging with an Autogenous Bone Graft.- 3.2.2.1 Revascularization.- 3.2.2.2 Heterotopia.- 3.2.2.3 Secondary Interpositional Corticocancellous Bone Graft.- 3.2.2.4 Primary Interpositional Autogenous Bone Graft.- 4 Prophylactic Use of the Neutralization Plate.- 4.1 Use of the Plate for Extensive Bone Cysts.- 4.2 Plating for the Removal of an Impacted Wisdom Tooth.- 5 Partial Prosthetic Arthroplasty.- 5.1 Indications.- 5.2 Principle and Usefulness of the Prosthesis.- 5.3 Design and Function of the Prosthesis.- 5.4 Technique of Insertion.- 6 Osteotomies.- 6.1 Sagittal Split Osteotomy of the Ascending Ramus (Laminotomy).- 6.1.1 Advantages.- 6.1.2 Disadvantages.- 6.1.3 Planning.- 6.1.4 Instrumentation.- 6.1.5 Anatomic Aspects of the Sagittal Split Osteotomy.- 6.1.6 Technique of the Sagittal Split Osteotomy (Laminotomy).- 6.1.7 Lag Screw Fixation.- 6.1.8 On Lag Screw Fixation as a Possible Cause of Sensory Disturbances.- 6.1.9 Removal of the Lag Screws.- 6.1.10 Indications: Shortening and Lengthening Osteotomy.- 6.1.11 Details on the Forward Sagittal Split.- 6.1.12 Functionally Stable Advancement with a Bone Graft.- 6.1.12.1 Method.- 6.1.12.2 Preliminary Fixation of the Fragments.- 6.1.12.3 Functionally Stable Fixation.- 6.2 Lateral Ostectomy.- 6.2.1 Principle.- 6.2.2 Indications.- 6.2.3 Preoperative Planning.- 6.2.4 Operation.- 6.2.5 Preliminary Fixation of the Fragments.- 6.2.6 Functionally Stable Internal Fixation.- 6.3 Anterior Ostectomy Combined with Sagittal Split.- 6.3.1 Principle.- 6.3.2 Indication.- 6.3.3 Preoperative Planning.- 6.3.4 Operation.- 6.3.4.1 Technique of Osteotomy.- 6.3.4.2 Internal Fixation.- 6.4 Triple Basoalveolar Ostectomy.- 6.4.1 Principle.- 6.4.2 Indication.- 6.4.5 Preoperative Planning.- 6.5 Operation.- 6.5.1 Internal Fixation.- 6.6 Genioplasty.- 6.5.1 Lag Screw Fixation.- 6.6 Concluding Remarks.- Foldout “AO Classification of Mandibular Fractures”.