Osteomyelitis (Bone Infection)

Infections of bones and joints are difficult problems that until recently were considered incurable. The old adage was that bone infection could never be completely cured. We no longer believe that to be true. The basic principle of treatment of bone infection is to remove all nonliving materials and space because these are regions where bacteria can hide from the body's immune defense system. To eradicate infection the body needs to deliver antibiotics, antibodies, and infection-fighting cells to the bacteria-infested areas. This is possible only if there is blood circulation in these areas. In general, when there is dead bone and hardware present, it is not possible to eradicate infection. Therefore, the first step is usually to remove all of the infected nonliving material, including hardware (this is called debridement) and eliminate the "dead space" created by the debridement. To achieve a cure of the infection, it is important to be aggressive and to treat the infection like a tumor. In other words, cut out more tissue than is necessary rather than risk leaving any dead infected tissue behind. Bone infection can be divided into the following three types by extent of involvement of the bone:

• Infections of the inside of the bone only (intramedullary infection). These occur after an intramedullary nail (rod) has been in place. These are best treated by a technique developed by the ICLL surgeons that will soon be published in the Journal of Orthopedic Trauma. This involves removing the metal rod that is in place and replacing it with a similar size custom-made antibiotic-filled cement rod. This fills the dead space and delivers a high concentration of antibiotics to the bone by diffusion out of the cement of the rod.

• Infections of part of the thickness of the bone: In these cases, we attempt to remove only the dead infected bone while preserving the surrounding living bone. This is not always possible, and it is sometimes preferable to remove all the surrounding living bone to be sure that the infection is eliminated. The hole in the bone often has to be sterilized and filled with an antibiotic-containing cement or other substance. The hole in the bone is then healed by using a bone graft or bone transport technique.

• Infections of an entire segment of the bone: In these cases, it is necessary to remove an entire segment of bone and any dead and infected surrounding soft tissue. The bone defect thus created is eliminated by one of two methods: bone transport or acute shortening with relengthening. Both of these methods use limb lengthening technology and biology. With bone transport, the length of the bone defect is maintained while the defect is filled by cutting the bone at one or both ends and lengthening a segment of bone across the defect until contact is made between the transport segment and bone on the other side of the defect. When the two ends meet, they usually have to be bone grafted for them to heal together. This requires an additional planned surgical procedure. Acute shortening with relengthening involves collapsing the bone defect by shortening the leg all at once until end-to-end contact is made between the two sides. The advantage of this method is that it eliminates the dead space all at once, which is one of the principles of treatment of infection. In contrast, bone transport eliminates the dead space gradually. This often obviates the need for bone grafting. To avoid leaving the limb short, at the same surgery, the bone is cut at one or two levels and lengthened gradually according to the methods described for lengthening in another section. In the end, the final result is the same between bone transport and acute shortening with relengthening. This was confirmed in a recent study comparing the two methods by the authors. The main difference in results is that there are more complications with bone transport than with acute shortening and relengthening and the former required more surgical procedures to accomplish because of the more frequent need for a bone graft. The main disadvantage of acute shortening with relengthening is limited by the size of the defect (defects of 8 cm or less), whereas transport is almost unlimited by the size of the defect, and that it is much more technically demanding than transport. The current method of acute shortening with relengthening was also developed by the ICLL surgeons who are equally adept at both methods.

The primary limitations for success with the treatment of bone infections is the immune fighting ability of the patient and the circulation of their limbs. Some patients have immune compromise due to disease or drugs. Diabetes is the most common immunocompromising disease. Obviously, positive HIV and AIDS are other examples of immunocompromising disease status. Patients who have had organ transplant and who are receiving anti-rejection medications, such as steroids, immuran, and methotrexate, or patients who are receiving chemotherapy for cancer or autoimmune disease (SLE, RA, etc.) are also immunocompromised. Patients receiving steroids for the treatment of other diseases are also immunocompromised.

The other group of patients who are immunocompromised are smokers. Smoking has many negative effects on bone. Most notably, it delays bone healing and can even prevent bone from healing. Secondly, smoking seems to interfere with the body's ability to fight bone infection. For these reasons, we make it a prerequisite that smokers agree to stop smoking before treatment. Although we recognize that stopping to smoke is very difficult, we feel that the patients must decide which is more important to them: their legs or their cigarettes.

In the past, the ultimate definitive treatment of bone infection was amputation. With current methods, our success rate at eliminating bone infection and getting the bone to heal with restoration of function is greater than 97%. The highest rate of complications and failure are in the immunocompromised patient and in the noncompliant patient (patients who are unwilling to follow our treatment recommendations and instructions). Therefore, amputation remains a viable option if all else fails in the rare case. For these reasons, we are unwilling to perform major reconstructive surgery in patients who cannot comply with treatment, including cessation of smoking.

Joint Infections

Infections of joints fall into two groups: joint infection and total joint replacement infection. The treatment of joint infection varies from small to major surgical procedures, combined with prolonged intravenously administered antibiotic therapy.

Joint infection refers to infection of a non-replaced joint. In the simplest scenario, we treat these by washing out the inside of the joint, placing a drain to let the fluid of the joint out, and intravenously administering antibiotics. In the more complicated cases, especially when the joint is destroyed by the infection, and in cases in which the adjacent bone is infected, the joint is excised (cut out) and, in most cases, fused or replaced. Fusion is the best operation for the ankle and wrist but may also be chosen for the knee, hip, elbow, or shoulder. Joint replacement is often chosen in these other joints, depending on the age of the patient and other factors.

Joint replacements are made of metal and plastic. When a joint replacement becomes infected, all attempts are made to try to save the joint. In very early cases, the infection may also respond to very aggressive wash out and debridement without removing the hardware. In more advanced cases, or when the previous more conservative treatment fails, it becomes necessary to remove the joint replacement hardware. Whenever possible, our goal is to sterilize the infected joint and re-replace the joint. In situations in which this is not possible for one or more reasons, the options are to fuse the joint or to conduct a biologic reconstruction. Our team of joint replacement and limb reconstruction experts works together to provide the patient with as many options as possible to achieve a stable, painless, and well functioning non-infected limb. This is one of the biggest advantages of our Center: we offer such a wide variety of treatment modalities, from the simplest to the most complicated, and we work together as a team to solve these complex problems.