Sparing Life and Limb

From OncoLog, September 2007, Vol. 52, No. 9

Sparing Life and Limb

by Sunni Hosemann

Jordan’s clear blue eyes twinkle and she breaks into a big smile as a text message appears on her cell phone. With an impish grin, she “texts” back with the dexterity that only a 13-year-old could manage. She’s the picture of an all-American teen: a sweet and somewhat shy smile, freckles, a ponytail, blue jeans, sneakers, and a T-shirt. But what one wouldn’t know just by looking at her is that, thanks to advances in limb-sparing technology, Jordan is lucky to have her own leg.

At age 11, Jordan began experiencing pain in her knee when she was playing softball. Perhaps a strain or an injury? It began to bother her more. Growing pains, maybe? It became more noticeable. An X-ray delivered bad news: Jordan had a tumor—an osteosarcoma—in her knee.

In another time and another place, Jordan would have required an above-the-knee amputation of her leg. Even today, she might have been spared the amputation but could have faced a dozen or more additional surgeries by the time she reached adulthood. Instead, physicians used a novel implanted prosthesis that “grows” with Jordan—without follow-up surgery—to replace the diseased bone.

Alternatives to amputation

For some time now, orthopedic surgical oncologists have been able to perform limb-salvage surgery using a variety of ingenious techniques and advanced prostheses that allow optimal function after removal of diseased bone. Depending on the size and location of the resulting defect, bone can be replaced by an endoprosthesis (an internal prosthesis usually made of metal), an autograft (bone transplanted from another area), or less commonly, an allograft (bone from a cadaver). “The technology behind prostheses for bones and joints is constantly improving,” said Christopher Cannon, M.D., an orthopedic surgeon who is assistant professor in the Department of Orthopaedic Oncology at The University of Texas M. D. Anderson Cancer Center. “This translates into better function for patients.” Jordan is the recipient of one of the latest advances in such technology.

Special challenge: patients who are still growing

Many bony tumors occur in the long bones of the arm or leg—the humerus or femur—and advances in endoprostheses have allowed patients to keep their own limbs. In an adult, it’s a matter of replacing the lost bone with a prosthesis suited to size and function. However, the most common tumors of the bone—osteosarcoma and Ewing sarcoma—frequently occur in children or adolescents who have not achieved full growth, and frequently these tumors occur in a location—the ends of long bones—that makes it impossible to spare the growth plate. According to Valerae Lewis, M.D., an orthopedic surgeon who is associate professor in and chief ad interim of the Department of Orthopaedic Oncology, in the past, even where a prosthesis could be put in place to spare the current limb, continued growth resulted in an unacceptable outcome: a dysfunctional growth discrepancy between the affected and unaffected limbs. In the case of a leg, this produced gait abnormalities that were obvious and untenable. Therefore, if a child had any significant growth left, amputation was the preferred treatment.

More recently, surgeons have used a limb-sparing approach in these children wherein an endoprosthesis is placed and subsequently lengthened as the child grows by adding modular increments. Each lengthening requires surgery, with the potential for complications such as infection. With this approach, a child might have 8–20 additional surgeries before reaching full growth, at which time a more permanent prosthesis would be placed.

Clearly, a prosthetic device that could accommodate growth was needed. For Jordan, Dr. Lewis used just such a device: it is a prosthesis that expands without additional surgery. The Repiphysis she used has a locked spring mechanism that allows controlled expansion of the prosthesis using an external electromagnetic device. Jordan has undergone two expansions so far. Expansion increments are between 1 and 2 cm, and expansions are done under general anesthesia. Eventually, expansion may be done as an outpatient procedure, but for the near term, Jordan will be admitted to the hospital overnight.

Jordan’s mother, Jeannie, considers herself fortunate to have found Dr. Lewis to treat her daughter. But for Jordan to have received this procedure, more than luck was involved. According to Dr. Lewis, candidates for this procedure must be chosen carefully. “Any expandable prosthesis is a large undertaking,” she said, “not only for the patient, but for the surgeon, the medical oncologist, and the family.” Success requires dedication to an aggressive rehabilitation program in the postoperative period (3–6 months of physical therapy) and diligent follow-up. “Both the patient and family must be committed to the procedure and a relatively long rehabilitation process,” she said. Lack of sufficient rehabilitation can lead to flexion contractures and poor functional results.

So, although this petite, ponytailed teen may be smiling and “texting” like all her friends, she has had to work at her recovery with a dedication not often demanded of someone her age, and her family also has made a considerable commitment to her recovery process. The reward: except for the surgical scar on her knee, her right leg looks just like her left leg.

Other challenges

Although most occur in the long bones, bone tumors do affect other locations and often call for other approaches when prostheses are not feasible, according to Dr. Lewis. One of her patients was a young woman who lost a significant portion of her pelvis to osteosarcoma; Dr. Lewis used the patient’s own fibula to construct a stabilizing hip scaffold. The woman recently gave birth.

Often, Dr. Lewis elects to use the patient’s fibula to replace a humerus and thus leave the patient with a functional and growing humerus. Using the patient’s own bone has distinct advantages: it is alive, it is vascularized, and when the physis is included, it maintains the ability to grow.

Sometimes, tumor size or location requires yet more innovation: Dr. Lewis has also created functional knee joints from ankles using a procedure called rotationplasty wherein the entire tibia, with nerve bundles intact, is rotated 180 degrees and reattached to the fibula, with the ankle joint becoming the new knee. In essence, this creates an amputation below the knee, which is far more favorable for the patient than an above-the-knee resection, and thus is a useful technique when sparing of the full limb is not possible. The procedure is a modification of a technique first described by J. Borggreve in 1930 for limb shortening and knee ankylosis secondary to tuberculosis. Patients who have this procedure do require a lower-limb prosthesis for bipedal ambulation but have been found able to walk for longer periods of time than those fitted with prostheses above the knee. Although the result is less aesthetically pleasing than that achieved by internal prostheses, these patients—unlike those with an endoprosthesis—are able to participate in vigorous, high-impact sports.

When the epiphysis (and therefore the growth plate) is not affected by the tumor, still other options exist for resecting the tumor and filling the resulting defect with bone, either by grafting it from other sites or by techniques like distraction osteogenesis, where the remodeling process seen in healing bone is put into use by transporting small (1 mm) segments of bone from an osteotomy in the same bone to gradually fill in the defect.

Limb-sparing procedures are very much customized to the patient based on the size and location of the tumor, the lifestyle and growth potential of that individual, and the patient’s desire and ability to handle the demands of recovery. A potential candidate for limb-sparing surgery should be evaluated by an orthopedic oncologist familiar with limb-sparing options, and this should happen before any biopsy is done, as some biopsy techniques may limit reconstructive options. Advances in imaging techniques have been critical to the success of this surgery, as it is now possible to better delineate tumor margins during treatment planning.

All of these procedures require more skill on the part of the surgeon—and more dedication on the part of the patient—than do amputations, but for young patients like Jordan, the importance of having her own leg may be hard for the rest of us to calculate.

For more information on limb-salvage surgical procedures, call Dr. Lewis at 713-792-5073. To refer a patient, visit www.mdanderson.org/departments/ortho/.

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