Tornetta Rockwood Adults 9781975137298 V2

Section One GENERAL PRINCIPLES

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Biomechanics of Fractures and Fracture Fixation Michael Bottlang, Daniel C. Fitzpatrick, Lutz Claes, and Donald D. Anderson

FIXATION CONSTRUCTS  23 Biomechanical Characterization of Fixation Constructs  23

INTRODUCTION  2

BASIC MECHANICAL CONCEPTS  2 Material Properties  2 Structural Properties  5 Load Transfer Through Joints and Fractures  6

Stiffness of Intramedullary Nail Constructs  24 Stiffness of External Fixator Constructs  25 Stiffness of Plate Constructs  25 Construct Stiffness and Fracture Healing  26 Improvement of Fracture Fixation  27

BIOMECHANICS OF FRACTURES  8 Traumatic Loads Resulting in Fracture  8 Physiologic Loads During Normal Activities  9 Osteoporosis  11 Periprosthetic, Interprosthetic, and End Screw Fractures  12

BIOMECHANICAL EVALUATION OF FIXATION CONSTRUCTS  28 Benefits and Limitations of Biomechanical Studies  28 Specimen Selection  30 Loading Considerations  31 Loading Modes  31

Outcome Parameters  34 Numerical Simulation  37

BIOMECHANICAL ASPECTS OF BONE HEALING  14 Interplay Between Biology and Mechanics  14

Natural Bone Healing  14 Primary Bone Healing  17 Delayed Union and Nonunion  18

SUMMARY  38

FRACTURE FIXATION STRATEGIES  19 Targeting a Fracture-Healing Mode  19

Fixation Strategies for Natural Bone Healing  19 Fixation Strategies for Primary Bone Healing  20 Creating a Durable Fixation Construct  20

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