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Bone Grafts

 

Table of Contents

  • Introduction
  • Autograft vs. Allograft
  • New Technology

    Midline cutaway pictured

    Introduction

    A basic part of any spinal fusion is the bone graft. Bone grafting is used for many types of orthopedic procedures that require bones to heal. Bone grafting is used in two main ways during orthopedic procedures:

    The most common use of bone graft is to stimulate the healing of bone . The bone graft is used like "fertilizer" to stimulate and speed the bone healing process. Bone tissue that is crushed into powder and placed around a fracture or a fusion site has chemicals in it that stimulate the nearby bones to heal. If the bone is taken from the person's own body, there may also be osteocytes (living bone cells) that survive being transferred to the new location and continue to do their work of making new bone. Even bone taken from someone else will stimulate bone to heal. But bone taken from the same person may be better because the chances are higher that it will have remaining live bone cells after the transfer.

    Provide Support

     

    Bone graft is also used for structure. Rather than crush the bone into fine pieces, larger pieces of bone are used to fill a gap between two bones. For example, if the surgeon removes a vertebra or disc, he may place a chunk of bone graft into the space. Because bone is rigid, it will hold the bones apart while the body grows to the ends of the graft. Over time the entire piece of bone that was grafted will be "remodeled" and replaced by the body with new bone. The time it takes to fuse depends on the size of the piece of bone that was used. It is sometimes a slow process that may take several years.

    Autograft vs. Allograft

    Much research is in progress to design bone graft substitutes, chemicals, and devices that stimulate the bones to fuse. It is well known that electrical current stimulates bone to grow. Many surgeons use electrical stimulation devices during the first weeks of surgery to speed up a fusion. Some artificial bone graft materials have been developed. For instance, sea coral, harvested from oceans, is sometimes used very successfully as the basis for a structural bone replacement. Other developments include

    • Demineralized bone matrix (DBM), which is a type of allograft developed from cadaver bones in a bone bank. The bone has the calcium removed and can be turned into a putty, sheet, or gel. The material can then be added to a graft site to improve the fusion.
    • Autologous growth factor (AGF), which is a solution used to stimulate bone growth. It is developed in a laboratory from blood platelets (the clotting part of blood). The mixture is usually used in combination with some form of structural support, such as autograft or fusion cages.
    • Bone morphogenic protein (BMP), which is a chemical added to bone graft to enhance bone growth when added to a fusion site.
       

    New Technology

    Much research is in progress to design bone graft substitutes, chemicals, and devices that stimulate the bones to fuse. It is well known that electrical current stimulates bone to grow. Many surgeons use electrical stimulation devices during the first weeks of surgery to speed up a fusion. Some artificial bone graft materials have been developed. For instance, sea coral, harvested from oceans, is sometimes used very successfully as the basis for a structural bone replacement. Other developments include

    • Demineralized bone matrix (DBM), which is a type of allograft developed from cadaver bones in a bone bank. The bone has the calcium removed and can be turned into a putty, sheet, or gel. The material can then be added to a graft site to improve the fusion.
    • Autologous growth factor (AGF), which is a solution used to stimulate bone growth. It is developed in a laboratory from blood platelets (the clotting part of blood). The mixture is usually used in combination with some form of structural support, such as autograft or fusion cages.
    • Bone morphogenic protein (BMP), which is a chemical added to bone graft to enhance bone growth when added to a fusion site.

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