MSK interventions open burgeoning new field

January 1, 2007
H.A. Abella
H.A. Abella

Half of the people in the U.S. older than 50 could suffer fractures caused by osteoporosis over the next 13 years, according to a 2005 Surgeon General's report. Such ominous predictions move musculoskeletal conditions to the top of a long list of chronic diseases confronting baby boomers.

Half of the people in the U.S. older than 50 could suffer fractures caused by osteoporosis over the next 13 years, according to a 2005 Surgeon General's report. Such ominous predictions move musculoskeletal conditions to the top of a long list of chronic diseases confronting baby boomers.

Image-guided interventions could offer minimally invasive treatment options for many of these conditions. Interventional and musculoskeletal radiologists say these procedures could also provide cost-effective solutions that would slow increasing healthcare expenditures.

"In interventional radiology in general, one of the biggest growth areas is oncology. Probably the least tapped area at the moment is musculoskeletal," said Dr. Peter L. Munk, a professor of radiology and orthopedic, vascular, and general surgery at the University of British Columbia.

Munk chaired the first symposium on interventional musculoskeletal radiology at the 2006 International Skeletal Society meeting held in Vancouver in September.

Interventional radiologists have developed techniques to treat tumors in the liver and other organs and produced a respectable body of literature in that area. Malignant disease affecting the bones, joints, and nerves and other soft-tissue ailments, however, have been confined to the background. They are coming to the fore now, said Munk, who is also director of musculoskeletal radiology at Vancouver General Hospital.

"Much of what interventional and musculoskeletal radiologists can do isn't yet appreciated," he said.

Surgery remains the standard of care for many age-related chronic and degenerative conditions affecting bone and soft tissues. That means ugly scars for patients and, in many cases, a painful, lengthy recovery. The main concern for healthcare in general revolves around increasing hospital costs. Also worrisome is the loss of productivity from a workforce in its final years before entering retirement. Ironically, lifestyle changes inspired by other healthcare anxieties, such as fear of cardiovascular disease, may be contributing to increased musculoskeletal risk.

A nationwide survey published in 2004 by the National Institute of Arthritis and Musculoskeletal and Skin Diseases found that more male adults and women of all ages are participating in competitive and leisure sports such as baseball/softball, basketball, bowling, golf, hiking, cycling, and soccer than ever before. Pro athletes and weekend warriors alike are suffering musculoskeletal injuries at increasing rates. The same survey found that adults aged 25 and older sustain about two and a half million sports- and recreation-related injuries annually.

The picture for youth doesn't seem any brighter. A study sponsored by the Centers for Disease Control and Prevention found that high school sports grew from about four million participants in the 1970s to more than seven million by the mid-2000s. Injuries increased as well. High school athletes currently account for about two million injuries, 500,000 doctor visits, and 30,000 hospitalizations annually (Morb Mortal Wkly Rep 2006;55[38]:1037-1040).

Despite recent advances in treatment for many musculoskeletal conditions, age-related or otherwise, most therapy remains invasive. Arthroscopic surgery, for instance, provides a much less invasive alternative than surgery, but it is a technically difficult and potentially risky procedure that could lead to complications. Interventional musculoskeletal procedures, many of which involve just a simple needle and are performed on an outpatient basis, could soon beef up the middle ground between conservative therapy and open surgery.

"These very simple musculoskeletal interventions are going to be in greater and greater demand once both physicians and the public learn about them," Munk said.

VERTEBRAL FRACTURES

One in three women and one in eight men in the middle-aged and elderly population worldwide will suffer at least one osteoporotic fracture during their lifetime. Vertebral fractures make up a significant proportion of these fractures, according to data from the International Osteoporosis Foundation and the European Society of Musculoskeletal Radiology's Osteoporosis Group.

About half of these patients will be able to resume normal activities, while the other half will be split between those who die and those who spend the rest of their life under treatment. Associated costs could increase more than twofold by 2050, according to members of these groups.

The standard treatment for patients with lumbar and thoracic compression fractures used to be painkillers, bed rest, and the patience to wait for lesions to settle down on their own. Just a few cases required surgery. But conservative therapy would keep some patients immobilized for a long period of time, and this practice has dire consequences for older patients. Vertebroplasty changed all that, said Dr. Cheryl A. Petersilge, president of the Society of Skeletal Radiology.

"These patients didn't really have a satisfactory treatment before and had to limit their activities. They now have new alternatives that allow quicker rehabilitation and return to normal activities and a better quality of life," said Petersilge, chair of radiology at the Cleveland Clinic Health System's Marymount Hospital.

BONE TUMORS

Treatment of metastatic tumors of the bone traditionally required narcotics to ease the excruciating pain and costly, sometimes mutilating surgeries. Interventionalists now treat these tumors with embolization and thermal ablation techniques. They also inject cement, as with vertebroplasty, which has the double effect of ablating the tumors and stabilizing the fractures caused by these malignancies.

Minimally invasive techniques provide for a range of osteoplastic procedures with palliation as well as treatment in mind. Clinical data include work in long bones, the thoracic cavity, and the hip. Treatment of the acetabulum has garnered attention lately, particularly its implications for mobility restoration in selected patients. Research is focusing on finding the most effective single or combined methods.

"There's an enormous variety of things we can do, but nobody's sure which is the best approach to bone disease. We are going to spend the next 10 years figuring out the optimal uses for these techniques," Munk said.

BACK AND NECK PAIN

Back pain is one of the most common neurological disorders, a leading cause of disability, and a very expensive ailment. Lumbar, dorsal, and cervical spine conditions-the result of trauma or degeneration-cost U.S. patients tens of billions of dollars each year, according to the National Institute of Neurological Disorders and Stroke.

Herniated vertebral discs that cause abnormal bulging of the spinal canal are often responsible for the pain. The interventionalist has several tools for the treatment of this condition:

  • steroid and anesthetic injections to the facet joints of the spine;

  • intradiscal electrothermal annuloplasty (IDET), an outpatient procedure that involves placing a special catheter to cauterize the posterior annulus of the disc;

  • percutaneous disc nucleotomy, which uses Coblation technology to ablate and remove tissue from the disc and is also marketed as Nucleoplasty to ablate and remove tissue from the disc;

  • percutaneous discectomy, an outpatient type of microsurgery;

  • nerve blocks allowing physicians to identify the nerves causing the pain using a small needle and a contrast agent, which are applied in the lumbosacral region but can also be used in the thoracic and cervical spine; and

  • oxygen-ozone ablation, consisting of an injection of this gas mixture into the disc and around the nerve root.

The only percutaneous disc decompression technique not approved for use in the U.S. by the FDA, ozone ablation has become widely popular in Europe, mainly in France and Italy. Current data available for the treatment of herniated vertebral discs with this technique show success rates of about 80%. IDET, on the other hand, remains controversial. Its efficacy has not been assessed in randomized controlled trials.

With the exception of IDET, however, all of these techniques offer patients credible treatment alternatives for back and neck pain, said Dr. Kieran Murphy, an interventional neuroradiologist at Johns Hopkins University.

"These are all excellent interventions," he said.

LIGAMENTS AND TENDONS

Injuries affecting ligaments, tendons, and joints of the shoulders, hips, knees, and ankles represent a lifelong scourge for athletes. A significant number of these injuries result in actual tears that have no recourse other than surgery, but impingement syndromes account for many that could be managed more conservatively.

Musculoskeletal radiologists are now using the injection of anesthetics such as bupivacain hydrochlorid to detect the source of pain. Once they determine where pain originates, treatment with steroid injection remains an option for symptom relief.

"We do a lot of intervention in ankles and in other soft-tissue injuries," said Dr. Philip Robinson, a consultant MSK radiologist at St. James University Hospital in Leeds, England.

Robinson and colleagues favor an MR-based diagnostic protocol to assess these injuries. After they have confirmed diagnosis, they use ultrasound guidance to break up scarred tissue with a needle or to inject a volume of anesthetic and, occasionally, steroids to treat the impingement. Many of their patients used to undergo arthroscopy for treatment, but now most don't need to.

Robinson recently published results on 10 consecutive Premier League soccer players with inversion injury of the ankle who later developed posterior talofibular impingement. These players underwent MRI and ultrasound-guided injections between 2001 and 2005. They tolerated the procedure without complications, showed symptom improvement, and quickly returned to competition (AJR 2006:187[1]:W53-58).

"Anybody with ankle impingement can benefit from these interventions, not just high-performance athletes," Robinson said.

VASCULAR MALFORMATIONS

Vascular malformations, particularly birthmarks, were treated by invasive means until fairly recently. These malformations range from mild skin tumors such as infantile hemangioma to the more aggressive Kaposiform hemangioendothelioma. Surgery for arteriovenous and lymphatic malformations can leave large areas of tissue necrosis and disfiguring scars, with a high rate of recurrence.

Interventional and musculoskeletal radiologists can treat these conditions more successfully because of their specific knowledge of vascularity, musculoskeletal structures, and their imaging skills, said Dr. Gerald M. Legiehn, an interventional radiologist at the University of British Columbia. The preferred technique is sclerotherapy with sodium tetradecyl sulfate or alcohol, which avoids the invasive effects of surgery. Transcatheter embolization and even radiofrequency ablation are sometimes used to treat a number of these lesions. Legiehn discussed his results using the technique during a presentation at the 2006 ISS meeting.

"Sclerotherapy really does displace a very unsatisfactory, very invasive treatment," Munk said. "The majority of people with venous malformations in North America are now probably going entirely untreated or inadequately treated. This would probably be one of the areas where image-guided treatment will make a particularly dramatic difference."

Probably the most common area of involvement for MSK radiologists, and the one least recognized, is their work toward minimally invasive means to obtain suspicious tissue samples for pathology labs. Open bone biopsies remain the gold standard, but radiologists are taking over this role in many institutions. Image-guided percutaneous biopsies will eventually replace surgical procedures, according to Munk.

"When surgeons perform a biopsy, they can't see or target the lesion the way radiologists can under imaging. I'm never going to target a part that looks benign, cystic, or necrotic. I can always find the best area to target," he said.

REWARDS AND RISKS

Though interventional and musculoskeletal radiologists may disagree on what technological and technical advances made possible the development of the subspecialty-CT fluoroscopy, MRI, ultrasound, vertebroplasty, or thermal ablation-the future of minimally invasive image-guided musculoskeletal interventions looks promising for both patients and physicians. The question remains, however, for what physicians?

Canadian radiologists don't fret much about turf, as provincial governments almost exclusively provide reimbursement, which is generally low. In the U.S., however, the field of minimally invasive intervention is generally more developed, lucrative, and competitive. Physicians such as orthopedic surgeons and neurosurgeons, who used to refer their patients, now perform many interventions themselves.

"The more people try to build their own practice, the more they want to do this stuff. In the past, vertebroplasty was done mostly by radiologists. Now other people say, 'Why should I send my patients for somebody else to do this procedure when I could learn to do it myself?'," said Dr. Louis A. Gilula, a professor of radiology, orthopedics, and plastic and reconstructive surgery at Washington University's Mallinckrodt Institute of Radiology in St. Louis.

Although surgeons perform mostly kyphoplasty, this procedure costs several times more than vertebroplasty. At least one study has shown substantial differences in the cost of vertebroplasty and kyphoplasty intervention kits at $400 vs $3400, respectively (Am J Neuroradiol 2004 May;25[5]:840-5).

The financial incentive to perform kyphoplasty attracts many specialists, including radiologists, another reason that discord is brewing among radiologists who perform either procedure. Physicians performing kyphoplasty can now get paid through Medicare's Diagnosis-Related Group system. This code pays only part of the cost, however, which means much of the expense will come out of the patient's pocket, Gilula said.

"With this code, these hospitals are getting paid to 'reduce' a fracture. They reel patients in and make money off it. That's why they like it. I have ethical problems with performing procedures that cost the system a tremendous amount of money without a clear benefit to the patient," he said.

Manufacturers fuel this competition. Many of the products traditionally marketed to radiologists are also being marketed to rheumatologists and orthopedic surgeons. Hologic, for instance, sells MRI, C-arm fluoro, and bone densitometry systems to rheumatologists and promotes office-based imaging services in its advertising.

Radiologists expect to retain their edge as imaging experts, however. Those with MSK expertise have an additional advantage.

"Very few people will become pure interventionalists, and some of them could have difficulty interpreting the MSK findings on their own. Having broader experience will make you a better clinician," Robinson said.

Many tools of the trade with which radiologists are familiar are improving. New experimental compounds, such as the cement used in osteoplasty procedures, will soon be available. Cortoss (Orthovita, Malvern, PA) induces bone regrowth in addition to structural support. Aprotinin, a purified protein from cow lungs used in cardiovascular disease and marketed as Trasylol (Bayer Healthcare, Leverkusen, Germany), appears in several European papers on the treatment of chronic tendon injuries.

Radiologists say their biggest challenge will be shifting to primary practitioner mode. Although many interventional radiologists actually have a clinic setup that allows pre- and post-treatment patient care, diagnostic radiologists do not generally support this trend, and those who do haven't been trained to deal with neurological problems. They might need help from outside specialists who are not big competitors, such as physiatrists, Gilula said.

Functioning as the pain physician is key for radiologists to compete effectively in most situations, said Dr. Joshua A. Hirsch, an interventional neuroradiologist at Massachusetts General Hospital in Boston.

"In our shop, patients are not referred in for a procedure, but as patients. We evaluate them, get their clinical history, perform a physical exam, review radiographic studies, treat them, and follow them. In essence, we are functioning as the patient's physician," Hirsch said.

Minimally invasive procedures remain grossly underutilized because most people do not realize they are available, much less what they can do, Munk said. Expanding their availability depends on radiologists-on the way they train a new generation of specialists and on how they pass the news about these musculoskeletal procedures along to referring physicians and their patients.

"It's all education. People just have to be aware of what can be done and why. The people in our own specialty are not really cognizant of it. How do you expect people outside of it to really understand?" Munk said.

Mr. Abella is assistant editor of Diagnostic Imaging.