Bone grafts treat traumatic injuries and help rejuvenate aging joints. Autografts use tissue from a person’s own body, while allografts use tissue from another person’s body.

The different types of bone graft surgeries have varying benefits and potential risks. Doctors consider autografts the gold standard, but these grafts also have a higher risk of complications at the surgical site.

Read on to learn more about allografts, autografts, and what they involve.

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According to the National Cancer Institute, an allograft is the transplant of an organ, tissue, or cells from one person to another person who is not their identical twin. During a bone allograft, a surgeon reconstructs a damaged or diseased area of a person’s joint using a bone and cartilage transplant.

Bone allografts are convenient, as there is plenty of potential donor tissue available. They may include a matrix of:

These are known as structural, particulate, and demineralized bone allografts, respectively.

People can also have synthetic allografts that consist of calcium phosphate or calcium sulfate. These have their own unique benefits: They provide structural support for the bone or joint, and the materials are widely available.

A bone autograft involves repairing bone with material from a person’s own body. Surgeons can take tissue from a person’s cancellous (spongy) bone, cortical (compact) bone, or bone marrow.

According to a review in the Journal of Orthopaedic Trauma, autograft is the gold standard in treating trauma-related conditions, including fractures and delayed healing or non-healing of bone breaks. However, it is not suitable for everyone.

Allografts and autografts each have their own advantages and disadvantages. The type of graft that is more suitable for a person depends on their unique circumstances.

Overall, research suggests that autografts offer better long-term outcomes.

One small study in the American Journal of Sports Medicine found that at least 10 years after anterior cruciate ligament surgery, more than 80% of young athletic people still had intact and stable grafts. However, the failure rate was more than three times higher for allografts than for autografts.

Similarly, a 2016 review and meta-analysis found that having an autograft significantly decreased the chances of problems developing in people having anterior cruciate ligament reconstruction.

A person does have a reduced risk of disease from an allograft if health professionals sterilize it with radiation first, but this can reduce its biomechanical function.

However, doctors also consider other factors when choosing between autografts and allografts. Some other benefits and risks include:

no chance of rejectionchance of rejection
no chance of disease transmissionchance of disease transmission
faster incorporation into the bodyslower incorporation
lower costhigher cost
lower availabilityhigher availability
potential donor site complicationsno risk of donor site complications in the recipient
potentially longer recoverypotentially shorter recovery

For autografts, a surgeon will take the tissue from a person’s body during the grafting procedure itself. For allografts, a surgeon will do this ahead of time.

Most of the tissue for bone allografts comes from people who choose to donate their organs and tissues when they die. If this is the case, a medical professional will assess the person’s medical history to determine whether they can safely donate bone.

If a donor is suitable, a medical professional will:

  • open up the joint and remove bone
  • test a sample of the donor tissue to check for microorganisms
  • shape the allograft into its final form
  • freeze or freeze-dry the allograft to preserve it
  • package the allograft
  • release it for implantation

In some cases, health professionals will sterilize the graft. The most common sterilization method they may use is radiation.

During allograft surgery, the surgeon replaces the damaged surface of the joint with precisely shaped healthy tissue from the donor.

First, a person will receive appropriate anesthesia and a health professional will clean the skin. Then, a surgeon will make an incision to access the joint before opening it up.

Next, the surgeon will:

  • expose and measure the defect in the bone
  • place a guide pin through the center of the surgical opening, at a right angle to the joint’s surface
  • widen the surgical opening just enough to remove the damaged cartilage and bone
  • measure the depth of the site where they will implant the bone graft
  • use a surgical instrument to remove a “graft plug” from the donor tissue
  • mark depth measurements on the graft plug and remove any excess bone so that it fits
  • wash the graft to remove blood and debris, and trim the bony edges to make insertion easier
  • gently insert the graft, which becomes compressed
  • fix any loose graft with absorbable pins or screws, if necessary

Autograft procedure

To perform an autograft, a surgeon will:

  • open the joint and remove any loose fragments of bone
  • use a guide pin to ensure they have a right angle when placing the new graft plug
  • remove any loose bone fragments
  • measure the damaged bone
  • drill the damaged bone with a drill bit the same size as the graft plug, using this to measure depth
  • insert the harvesting tool into the site from which the graft will come, and drive it in to the same depth
  • place the graft into a delivery system, which inserts the graft in the right location
  • make sure the graft is not too prominent or recessed

If the graft protrudes or recedes by more than 1 millimeter, this can cause the graft to fail.

Generally, experts regard autografts as the most effective type of bone graft procedure. However, a person opting for an autograft should consider that the graft material needs to come from a second surgical site on their body.

This can possibly mean they need to spend longer in a hospital than they would for an allograft. The second surgical site can also cause discomfort after the procedure, depending on the location and whether any complications occur.

A person’s body takes longer to accept an allograft, but the body does not have the additional work of healing a second surgical site. The surgery length and hospital stay for an allograft can be shorter.

Xenografts involve taking bone or other tissue from a donor that is not the same species as the recipient. For example, a person might receive tissue from the body of an animal.

Alternatively, scientists might take tissue from a human and transplant it into mice for research purposes. This is known as a patient-derived xenograft. Researchers can use this to test cancer drugs and other types of treatment before giving them to a person.

Orthopedic allografts involve taking bone tissue from a donor and transplanting it into a recipient. Alternatively, a person can have an autograft, which involves taking tissue from another site on their own body. There are benefits and potential risks to both procedures.

Whether a person has an allograft or an autograft will depend on their situation. Autografts can provide better results, but they involve recovering from two surgical wounds instead of one, and less donor tissue is available for them.