Essential Biomechanics for Orthopedic Trauma. A Case-Based Guide

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Preface Contents Editors Contributors Part I: Stress, Strain, and Young’s Modulus—How They Relate to Fracture Healing 1: Biomechanical Principles of Fracture Healing Introduction Material Strength Stress-Strain Anisotropy Fatigue Viscoelasticity Structural Strength Size Material Distribution Stress Concentrations Clinical Implications References 2: Perren’s Strain Theory and Fracture Healing Introduction Bone Fracture Mechanical and Biomechanical Effects Biology of Fracture Healing Biomechanics of Bone Healing Methods of Fracture Stabilization Conservative Fracture Treatment Relative Stability Indirect Fracture Healing: Perren’s Strain Theory Absolute Stability Direct Fracture Healing: Biomechanics Summary References 3: Case Studies in Fracture Healing and Nonunions Introduction Primary or Direct Fracture Healing Case 1 (Fig. 3.1) Failure of Fracture Healing Case 2 (Fig. 3.3) Secondary Fracture Healing Case 3 (Fig. 3.4) Secondary Fracture Healing Case 4 (Fig. 3.5) Case 5 (Fig. 3.6) Hypertrophic Nonunion Case 6: Failed Bone Healing (Fig. 3.8) Conclusion References Part II: External Fixation Principles with Case Examples 4: Biomechanics of External Fixators for Fracture Fixation: Uniplanar, Multiplanar, and Circular Frames Introduction Indications for External Fixation Biomechanics of External Fixator The Importance of Pins and Wires in Biomechanics of External Fixators Summary References 5: Diaphyseal Fractures Introduction Implant and Anatomic Considerations Pins Clamps Rods Anatomic Considerations Indications for Temporary External Fixation Damage Control Orthopedics Provisional Fixation Construction of External Fixator Frames Pin Insertion Technique Management of Diaphyseal Fractures Management of Intra-articular Fractures Complications and Pin Care Conclusion References 6: Periarticular Fractures Introduction External Fixation for Temporary Stabilization External Fixation for Definitive Treatment Technical Issues with Periarticular External Fixation Advantages of External Fixation in Periarticular Fractures Current Indications Biomechanics of Periarticular External Fixation—General Principles Definitive Frames Case 1: Temporary Joint-Spanning External Fixation Case 2: Same-Side Definitive External Fixation Case 3: Articulated External Fixation Conclusions References 7: External Fixators for Limb Lengthening General Principles Biology of Distraction External Fixator Construction Mechanical Modulation to Encourage Bone Formation Biological Adjuvants Complications Integrated Techniques Lengthening Over a Nail (LON) Lengthening and Then Nailing (LATN) and Transport and Then Nailing (TATN) References 8: External Fixators for Deformity Correction Introduction Why Circular Fixation? Deformity Assessment and Strategy Type of Circular Frame Circular External Fixator Stability Need for Neurolysis When to Remove the Frame? Complications Summary References Part III: Tension Band Wire Principles with Case Examples 9: Biomechanics of Tension Band Constructs for Fracture Fixation Introduction Key Concepts for Tension Band Constructs Determine the Tension and Compression Surfaces of the Fracture Ensure the Fracture Can Withstand Stable Compression, with an Intact Opposite Cortex Apply Fixation to Withstand Tension Case 1 Why This Works Case 2 Why This Works Case 3 Why This Works Conclusion References 10: Olecranon Fractures Introduction Descriptive Olecranon Fracture Classification Indications for Olecranon Fracture Tension Band Surgical Tips and Tricks Based on Biomechanical Studies K-Wires Wire Conclusion References 11: Patella Fractures Introduction Anatomy Biomechanics of the Extensor Mechanism and Its Relation to Injury General Management Principles Case 1 Physical Examination Nonoperative Management Case 2 Vertical Fractures Case 3 Case 4 Modified Anterior Tension Band Wiring with Kirschner Wires Surgical Technique: Modified Anterior Tension Band Wiring with Kirschner Wires Case 5 Case 6 Tension Band Wiring Using Cannulated Screws Surgical Technique Adjunctive Techniques Outcomes References Part IV: Plating Principles with Case Examples 12: Biomechanics of Plate and Screw Constructs for Fracture Fixation Introduction A Historical Perspective Biomechanical Functions of a Plate Biomechanical Properties of a Plate Conclusions References 13: Nonlocking Plate Functions Compression Plating Diaphyseal Compression Plating: Patient Example and Surgical Technique Neutralization/Protection Plating Neutralization Plating Patient Examples Buttress/Antiglide Plating Buttress/Antiglide Plate Function Patient Examples Tension Band Plating Tension Band Plating Patient Examples References 14: Nonlocking Plate Functions 2 Bridge Plating Length of the Plate Working Length of the Plate Screw Design and Density Case 1: Bridge Plate Why This Works Wave Plate Case 2: Wave Plate Why This Works Fixed Angle Devices Case 3 Why This Works Case 4: Dynamic Condylar Screw Why This Works Case 5: Sliding Hip Screw Why This Works Conclusion References 15: Locked Plating Introduction Monoaxial/Unidirectional Locking Screws Polyaxial/Multidirectional Locking Screws Flexible Locking Summary References Part V: Intramedullary Nailing Principles with Case Examples 16: Biomechanics of Intramedullary Nails Relative to Fracture Fixation and Deformity Correction Introduction Biomechanics Fractures and Deformities Case Examples Case 1: Transverse Midshaft Femur Fracture (Fig. 16.1) Why This Worked Case 2: Comminuted Distal Femoral Shaft Fracture (Fig. 16.2) Why This Worked Case 3: Comminuted Femoral Shaft Fracture with Long Lateral Butterfly Fragment (Fig. 16.3) Why This Worked Case 4: Segmental Tibia Fracture, Including Proximal Metaphyseal Fracture Line (Fig. 16.4) Why This Worked Case 5: Humerus Fracture Nonunion After Nailing (Fig. 16.5) Why This May Not Have Worked References 17: Diaphyseal Fractures Introduction Case 1 Background Treatment Discussion Case 2 Background Treatment Discussion Case 3 Background Treatment Discussion References 18: Periarticular and Intra-articular Fractures Introduction Key Concepts for Intramedullary Nailing in Peri- and Intra-articular Fracture Advantages and Disadvantages Reduction Methods to Overcome Biomechanical Disadvantages Advances in Interlocking Bolts Cases Case 1 Why This Did Not Work Case 2 Why This Did Not Work Case 3 Why This Did Not Work Case 4 Why This Worked Case 5 Why This Worked Case 6 Why This Worked Case 7 Why This Worked Case 8 Why This Worked Recent Biomechanical Studies Comparing IM Fixation and Plating Conclusion References 19: Use in Nonunions and Malunions Introduction Key Concepts for Intramedullary Malunion and Nonunion Repair Manage Adjacent Joint Mobility Determine the Etiology Recognize the Deformity and Restore Axis Preserve the Local Biologic Environment Maximize Stability in the Short Segment Case 1: Tibial Exchange Nailing Why This Works Case 2: Closed Femoral Shortening Why This Works Case 3: Tibial Diaphyseal Metaphyseal Clamshell Osteotomy Why This Works Case 4: Recalcitrant Distal Femur Plate Nonunion Exchanged to Nail Why This Works Conclusion References 20: Use in Arthrodesis Introduction Key Concepts for Intramedullary Arthrodesis Case 1 Why This Works Case 2 Why This Works Case 3 Why This Works Case 4 Why This Works Case 5 Why This Works Case 6 Why This Works Case 7 Why This Works Conclusion References 21: Intramedullary Lengthening and Compression Nails Introduction Preoperative Assessment Intraoperative Execution Postoperative Protocol Case 1 Why This Worked Case 2 Why This Worked Case 3 Why This Worked Complications Failure to Distract Crown Failure Premature Consolidation Regenerate Insufficiency MRI Incompatibility Corrosion and Late Failure Compression Nail and Staged Lengthening Conclusion References Index