Today's News

Saturday, March 13, 2004

Panel examines value of minimally invasive TJR

The introduction of minimally invasive procedures for total joint replacements has cre-ated quite a stir among media and patients. At a press briefing Wednesday, four orthopaedic surgeons shared their experiences and debated the pros and cons of minimally invasive hip and knee replacements.

The featured surgeons included: Thomas P. Sculco, MD, surgeon-in-chief, Hospital for Special Surgery; and professor of orthopaedic surgery, Weill Medical College of Cornell University, New York; Richard A. Berger, MD, assistant professor of orthopaedic surgery at Rush-Presbyterian-St. Luke's Medical Center, Chicago; David S. Hungerford, MD, professor, department of orthopedic Surgery at Johns Hopkins School of Medicine, Baltimore; and Peter M. Bonutti, MD, FACS, of St. Anthony's Memorial Hospital in Effingham, Ill.

When less is more
Approximately 300,000 hip replacements are performed annually in the United States alone, according to Dr. Sculco, who began performing minimally invasive surgeries (MIS) for total hip replacements (THR) in 1996. He began these surgeries as a response to his patients' expressed displeasure with the cosmetic appearance of the standard procedure, as well as their desire for a more rapid recovery, a reduced length of stay and a reduction in cost.

Although minimally invasive procedures, using a 6 cm to 10 cm incision, have become routine for 95 percent of his patients, Dr. Sculco pointed out that this approach is not for everyone. It requires an experienced surgeon, special instrumentation and proper patient selection.

Patient selection, in fact, is key. Although not a universal rule, patients who are obese or who may be overly muscular in the hip area may not be good candidates for MIS. With the right patient, however, these techniques result in less soft tissue trauma and less time in surgery. MIS decreases the blood loss and allows patients an earlier return to a normal gait without an increased risk for complications.

Patient selection, in fact, is key. Although not a universal rule, patients who are obese or who may be overly muscular in the hip area may not be good candidates for MIS. With the right patient, however, these techniques result in less soft tissue trauma and less time in surgery. MIS decreases the blood loss and allows patients an earlier return to a normal gait without an increased risk for complications.

Patient selection, in fact, is key. Although not a universal rule, patients who are obese or who may be overly muscular in the hip area may not be good candidates for MIS. With the right patient, however, these techniques result in less soft tissue trauma and less time in surgery. MIS decreases the blood loss and allows patients an earlier return to a normal gait without an increased risk for complications.

Outpatient hip surgery
In Chicago, Dr. Berger's team has developed and implemented comprehensive protocols for before, during and after surgery to assess the feasibility and safety of total hip replacement on an out-patient basis. His initial research study began in 2001 and ended early in 2003. It involved 100 patients, ranging from 40 years to 75 years of age. Although none of the patients in this initial study group was very elderly, Dr. Berger has since performed outpatient THR in older patients with excellent results.

"With MIS, outpatient surgery is feasible and safe," said Berger. "These procedures can be done on a large number of patients if the surgeon and the facility are willing to adopt the necessary methods."

The "methods" that must be adopted include carefully defined and articulated patient support mechanisms before, during and after surgery. Patients attend a class where they learn about pain management and how to walk on crutches. They also donate two units of blood that they get back during and immediately after surgery. A regional anesthetic is used for surgery.

Discharge is permitted only when strict criteria are met. In addition to exhibiting stable vital signs, the patient must be able to get in and out of both a bed and a chair independ-ently, walk 100 feet, and ascend and descend a full flight of stairs. Furthermore, the patient must be able to tolerate a regular diet and have adequate pain control from oral analgesics. A visiting nurse stops by for blood draws after the patient goes home, and home physical therapy is utilized until the patient can drive.

With experience, Dr. Berger and his team have become better at doing the surgery as well as managing other potential problems such as nausea, dizziness or hypertension after surgery. Dr. Berger makes only two small incisions-4 cm to 5 cm long. He uses the outpatient MIS approach for about 80 percent of his patients, who make an impressively speedy return to their normal activities. On average, patients discontinue crutches and drive within six days, return to work in eight days, and can walk without a cane in nine days. They resume activities of daily living within 10 days, and those who wish can walk a half mile within 16 days!

Knee replacement
More than 325,000 total knee replacements (TKR) are performed each year in the United States. That number is expected to jump to 450,000-more than 1,200 a day-before the end of this decade because of aging baby boomers, a more active population with post-athletic injuries, and greater numbers of overweight and obese people. Hundreds of thousands of people each year, therefore, will be looking to identify the best knee replacement procedures for this surgery. Dr. Hungerford took a skeptic's view, pointing out that there is no convincing evidence that an MIS TKR benefits the patient in any meaningful way.

"Nonetheless, MIS has become a buzz-word, well on its way to being a mantra," he said. "Patients ask for it without knowing why. Surgeons advertise it without knowing how."

Dr. Hungerford reviewed 275 revision TKR performed at Johns Hospital Medical Center between 1987 and 1997. The original surgeries were all performed using the standard approach with a larger incision that presumably provided adequate visibility. A review of preoperative X-rays of the 275 revisions showed that 75 percent had technical failures such as malalignment. Dr. Hungerford believes the cause was surgeon error.

"If the surgeon, with full exposure, cannot reproducibly and reliably align the knee, what will the outcome be with limited exposure?" he asked. "If MIS becomes widespread in TKR, there will be a significant and predictable increase in the number of technical failures. Even in those that are successful, there will not be a significant improvement in any of the parameters that patients and physicians should care about-decreased length of stay, improved range of motion, shorter recovery, or less pain."

Dr. Hungerford urged surgeons who are currently getting good results not to be seduced by smaller incisions. "If you are not getting good results with your current techniques," he said, "MIS will not help you."

He also had advice for patients. "Ask the surgeon how many cases he has done using this new technique," he says. "The whole issue of incision size is being blown out of proportion and it is not something that should be marketed directly to the patient. It is also not something that should be touted as the next best 'latest and greatest' until it is proven to be so. The claims that are made on some Web sites 'advertising' MIS are nothing short of fraud."

Long-term gains
Dr. Bonutti also based his opinions about minimally invasive knee replacements on personal experience. Unlike Dr. Hungerford, however, Dr. Bonutti would opt for MIS in TKR. Having performed more than 500 such surgeries, he has been successful with incisions as small as 6 cm.

While Dr. Bonutti is pleased with the short-term benefits of the procedure for his pa-tients, improving the long-term benefits is his passion. "Unlike THR, which patients are extremely happy with, TKR patients always have a disability," he said. "There is permanent functional deterioration because the muscles have been cut. Muscle damage is always permanent."

A key feature of MIS is to avoid everting the patella and dislocating the patellafemoral joint. A standard knee replacement requires that the surgeon cut into the kneecap tendon and the quadriceps tendon, so all the quadriceps muscles are affected. Dr. Bonutti and his team have developed a technique that doesn't cut into the tendon at all, but goes along the inside of the kneecap and splits the muscle along the fibers. That provides access to the knee without dislocating the patellofemoral joint.

After four years, Dr. Bonutti's patients continue to do well. Although discharge criteria are very strict, patients can go home independently within three days after surgery, walk with a cane and drive within 12 days-compared with 8 to 12 weeks with standard surgery. "The driving force is my patients," said Dr. Bonutti. "I want to help them get back to their lifestyle faster. This is what medicine is all about."

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Last modified 13/March/2004