Variables that Influence Fracture Healing

1. Variables that Influence Fracture Healing

2. Severe soft tissue damage associated with open and high energy closed fractures • Infection • Segmental fractures • Pathologic fractures • Fractures with soft tissue interposition • Poor local blood supply • Systemic diseases • Malnutrition • Vitamin D deficiency • Corticosteroid use • Poor mechanical fixation

3. Injury Variables • Severe open fractures • Soft tissue disruption • Fracture displacement • Significant bone loss • Management • Vascularized soft tissue flaps to cover bone exposed • Debriding of infected bone and soft tissue • Appropriate antibiotic treatment

4. Intra-articular Fractures • Extend into joint surfaces • Challenges • Unstable joint • Delayed healing or non-union • Joint stiffness • Segmental Fractures • Two level fracture pattern impairs or disrupts the intramedullary blood supply to the middle fragment

5. Soft Tissue Interposition • Suspected when bone fragments cannot be brought into apposition or alignment during attempted closed reduction • Damage to the Blood Supply • May result from a severe soft tissue and bone injury or from the normally limited blood supply to some bones or bone regions

6. Patient Variables • Diseases or Disorders • Diabetes • HIV infection • Age • Rate of healing declines with increasing age • Decreased number and function of stem cells • Decreased chondrogenic potential of the periosteum • Changes in local signaling at fracture site • Impaired vascularization

7. Nutrition • Cell migration, proliferation and matrix synthesis necessary to heal a frature requires substantial energy • There is a need for a steady supply of proteins and carbohydrates

8. Systemic Hormones • Corticosteroids • Thyroid hormone, calcitonin, insulin and anabolic steroids • Nicotine Use • Unknown mechanism • Possible that nicotine inhibited vascularization of autogenouscancellous bone grafts

9. Tissue Variables • Form of bone (Cancellous or Cortical) • Cancellous bone • Large surface area creates many points of bone contact rich in cells and blood supply • Cortical bone • Much smaller surface area per unit volume • Less extensive internal blood supply

10. Bone Necrosis • healing depends entirely on ingrowth of capillaries from the living side or the surrounding soft tissues • Bone Disease • Pathologic fractures that require less force than necessary to break normal bone • Osteoporosis, malignant bone tumors, osteomalacia, fibrous dysplasia • Infection • Many cells must be diverted to wall off and eliminate the infection and energy consumption increases • Necrosis of normal tissue and thrombosis of blood vessels

11. Treatment Variables • Apposition of Fracture Fragments • Decreasing the fracture gap decreases the volume of repair tissue needed to heal a fracture • Loading and Micromotion • Loading a fracture site stimulates bone formation while decreased loading slows fracture healing • Fracture Stabilization • Prevents repeated disruption of repair tissue • May cause nonunion