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Orthopedic Services
Glendale Adventist Medical Center
1509 Wilson Terrace
Glendale, CA 91206
Ph: (818) 409-8000

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As a family, we just came away from a two-hour meeting with surgeons who are trying to help our father who has a severe arm fracture. He's a farmer and made the mistake of getting too close to a piece of equipment that can chop your arm off. Instead, he ended up with an arm bone that's now in three major pieces. The problem is -- those three pieces have large spaces bewteen them. They are talking about doing a two-part procedure called induced membrane and using bone from a bone bank. They explained it all but can you help us understand all this a bit better?

Sometimes bone fractures are so severe the bones of the arm or leg can't just be lined up, put in a cast, and heal on their own. Bones that are broken into several (or even many) pieces with space between the pieces create a condition called segmental bone loss. When this happens, the surgeon is faced with a very complex and complicated surgical situation. And the patient often endures multiple surgical procedures, delays in healing, and a very long recovery time. In the worst case scenario, the patient goes through all that only to end up having the foot or hand, arm or leg amputated. Now this new two-stage surgical procedure you have been introduced to has had some good early success. It's called the induced membrane technique for bone reconstruction. In the first step, a temporary spacer is placed in the area of bone loss. The implanted device is called a polymethylmethacrylate (PMMA) spacer. PMMA is a type of cement that helps hold everything together. The spacer is "bioactive" meaning it will stimulate bone growth. An antibiotic is also mixed in with the cement to help prevent infection. In the second stage, the membrane is filled with allograft bone graft material taken from a bone graft (allograft means it is donor tissue from a bone bank). Before the spacer can be put in place, the surgeon debrides (cleans out and removes) all dead or infected tissue. This preparatory step helps reduce the risk of infection and loss of tissue later. Along with the spacer to restore normal bone length, hardware (metal rods, plates, and/or screws) is used to hold the bone in place. Any injury to the surrounding tendons or muscles is also repaired. Once the soft tissues around the damaged area are healed (i.e. stable), then the cement spacer is filled with bone chips and shavings. There are many potential advantages to this idea of creating a membrane to protect the local tissues while helping healing. For example, the bone graft is firmly held in place, preventing soft tissues from growing into the healing bone. The technique prevents bone graft resorption while actually stimulating blood supply to the area. The membrane even seems to help foster bone growth. And the cement spacer itself creates a mild inflammatory response, which also speeds up healing. The cement spacer stays in place for one to two months -- long enough to allow the membrane to become active. Removal of the spacer may be delayed if there is significant soft tissue injury that needs more time to heal. Recovery time is still lengthy with full weight-bearing for leg injuries achieved six to 10 months later. Severe arm and/or hand injuries treated this way also require many months for healing and rehab to take place. Full healing of the fractured bone can take up to a full year. But surgeons and patients agree that the time delay is worth it if the limb can be saved from significant shortening or even amputation. The idea of creating a membrane to help surgically manage severe or large bone defects caused by fractures has shown some good success. Studies done so far have been small without the benefit of long-term follow-up. But the surgeons who have used this approach are enthusiastic about the positive results they have had with their patients. More studies are needed to help identify the best materials to use to create this healing membrane. Likewise, it would be helpful if surgeons had a better idea as to the optimal time frames for each step of the procedure. For now, it appears that managing segmental bone defects with this two-stage induced membrane technique reduces complications, provides a faster healing and recovery time, and prevents limb shortening or amputation.


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