Spring/Summer 2001
 
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Medical Updates


One Tiny Cut to Replace a Hip

At a medical meeting in Miami, James Wenz floored fellow orthopedic surgeons when he showed them a videotape of the hip replacement procedure heís been using. Most of them, he says, "were pretty amazed." What staggered the orthopedists was the small incision Wenz makes.

Small in his case means a 7 centimeter cut—about 3 inches—compared with the foot-long slit used in conventional hip replacement surgery. With such a minimal incision, Wenz is able to cut into less tissue and muscle than in the typical surgery, which for the patient means a less-painful, speedier recovery. "With this surgery, the majority of people can put their full weight on their hip the next day," Wenz reports. In the typical approach, the pain and the time it takes for muscle to repair keep patients on walkers or crutches for up to 12 weeks.

Making only a 3-inch incision, orthopedic surgeon James Wenz, above right, is able to expose the top of the thigh bone (top insert), which he replaces with a titanium implant (bottom inset). The mini-incision means faster recovery for the patient.
Making only a 3-inch incision, orthopedic surgeon James Wenz, above right, is able to expose the top of the thigh bone (top insert), which he replaces with a titanium implant (bottom inset). The mini-incision means faster recovery for the patient.

The main criteria for pulling off this novel hip replacement is experience. The surgeon needs to visualize through touch anatomy thatís hidden away. Wenz, whoís done more than 300 of the procedures, is able to figure out precisely where to operate by studying preoperative X-rays and by very carefully palpating the terrain of the hip beneath the skin to form an image of its shape and location. His incision needs to provide access to both the top of the femur or thigh bone, in which he will insert the stem and head of the implant, and the hip socket, where he will attach a plastic-lined metal cup that houses the head. A mistake of just centimeters wonít allow enough room to insert the implant. "If you donít get the location absolutely perfect, you canít do the procedure," Wenz makes clear.

Some orthopedic surgeons have been reluctant to do the mini-incision hip replacements, because in early operations there appeared to be a greater likelihood that the implant would fall out of the hip socket. Wenz has avoided that problem by preserving the capsule of tissue that extends from the socket to cover the head or ball of the implant stem. In the conventional approach, this tissue is removed.†

"We cut it open and fold it out, and then at the end of the procedure fold it back in and suture it down," Wenz explains. The process reduces risk of dislocation.

The two categories of patients for whom the procedure doesnít work are those with unusual hip anatomy and people whoíve already had hip-replacement surgery. But Wenz now uses the technique on almost all of his patients and believes that as instruments evolve and surgeons become more confident with the approach, it will become the standard way to do total hip replacement.

Gary Logan

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Conductive Hearing Loss

The teeth marks on Thomas Alva Edisonís original phonograph tell all, says otolaryngologist Lawrence Lustig, M.D.: Edison, who Lustig says "probably had a pretty good working cochlea or inner ear, but also some major conductive hearing problems, used to bite down on the record playerís wooden exterior to get the sound to his inner ear so he could hear what was coming from the phonograph. Because bone is an effective transmitter of vibrations, it can carry sound waves to the inner ear in people with damaged middle and outer ears.

Otolaryngologist Lawrence Lustig snaps a hearing aid onto the tiny, titanium post embedded in the skull of patient Phyllis Earhart, giving her left ear the ability to hear for the first time.
Otolaryngologist Lawrence Lustig snaps a hearing aid onto the tiny, titanium post embedded in the skull of patient Phyllis Earhart, giving her left ear the ability to hear for the first time.

Were Edison alive today, Lustig could offer another way to help his hearing problem. By implanting a tiny titanium post into the mastoid bone behind the ear, the otolaryngologist gives patients with conductive hearing loss, due to blocked or underdeveloped ear canals, a means to amplify sounds to their inner ears. In the 30-minute outpatient operation under local anesthesia, Lustig first cuts a small horseshoe-shaped flap behind the ear, and drills a small pilot hole to house a post, which he screws and embeds firmly into the bone. Then, he removes soft tissue over the bone so the patientís skin will adhere to it the way skin sits on a fingernail bed, tight and immobile. Finally, Lustig places a small mounting bracket on the screw, which actually rises above the surface of the skin, for the hearing aid. After three months of healing, the aid is snapped to the post and turned on.

A recent study of 40 patients whoíd had the procedure showed that amplification improved dramatically in 80 percent. "Itís fantastic," says 67-year-old Phyllis Earhart of Red Lion, Pa., who had lost all hearing in her left ear because of calcium deposits. "Now I can hear like everyone else."

Because conventional hearing aids and ear surgery are not options for patients like Earhart, many would remain significantly hearing-impaired without the procedure, which is available at only a handful of U.S. centers.

GL

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New Hips for Little People

In another step forward on the hip-replacement front, orthopedic surgeons Michael Ain and Frank Frassica have come up with techniques that make the operation available to a group of patients whom doctors usually turned away—those whose full height is under 4 feet because of stunted and deformed bone growth known as skeletal dysplasia.

Until recently, the specially designed artificial hips and surgical tools necessary for people this small werenít available. "You canít just take an off-the-shelf artificial hip," Ain explains. The diminutive, irregular bone structure and poor bone quality of these patients also makes them technically challenging for surgeons to operate on, as do conditions like neck instability. "Physicians would simply tell them they werenít candidates for the hip surgery," Ain says.

Now Ain and Frassica have collaborated with biomedical engineers to design smaller prostheses and instruments, especially adapted to these patients. They use a dental burr-like instrument, rather than a conventional orthopedic drill to carve out a canal in the thigh bone for the stem of the hip implant. They also create smaller, computer-generated prostheses with special CT scans.

Key to success in these complicated cases is surgical experience and clinical expertise. Historically, Hopkins has had a large interest in skeletal disorders, Ain notes, citing the world-renowned Greenberg Center for Skeletal Dysplasias: "It lets us push the envelope in offering new kinds of help to these small people."

GL

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Snaking Up on the Aorta

Charlie Rigglemanís scar could have killed him. The three-foot long mark—an aftermath of three open chest surgeries—stretched from the middle of his back, around his side, and across the length of his belly. The tissue was so dense it had caused one of Rigglemanís lungs to adhere to his chest wall.

Such was the situation when a Pennsylvania doctor noticed a balloonlike bulge in the aortic artery just above the 72-year-old Rigglemanís heart. Riggleman, who had coughed up a washbasin full of blood, was at a very high risk of bleeding to death. The aneurysm needed repairing, and quickly, but surgeons were reluctant to perform another invasive chest operation. The scar tissue was blocking access to the aorta, making surgery both difficult and risky.

Interventional radiologist Lawrence Hofmann with the life-saving stent he uses in high-risk thoracic aneurysm patients.

Interventional radiologist Lawrence Hofmann with the life-saving stent he uses in high-risk thoracic aneurysm patients.

Only one option remained—a minimally invasive procedure now being tested here by interventional radiologist Lawrence "Rusty" Hofmann, M.D. Itís a technique available at only about a dozen sites worldwide. "But," says Riggleman, "it was the only logical choice."

Unlike conventional surgery in which a large incision in the patientís side or abdomen provides access to the aorta, this new approach relies on catheters to enter the giant artery. First, a surgeon makes a three-inch incision in the groin and femoral artery. Then, using real-time X-ray imaging, Hofmann inserts a catheter containing a 6-inch wire tube—a stent graft—at its tip and slides the catheter up the aorta to the thoracic region until the graft extends just above the aneurysm.

"Itís especially tricky when the aneurysm is in the arch of the aorta," Hofmann admits, because itís close to the artery that supplies blood to the left arm, and you donít want to block that with the graft.

Once the stent is in place, Hofmann quickly pulls a tiny string that releases the self-expanding tube. Immediately, blood begins to flow through the graft. Within hours, the aneurysm clots and over time diminishes in size.

The novel technique offers a number of benefits. Unlike the open procedure, the aorta doesnít have to be clamped, which means organs like the kidney or liver are not at risk of failing, due to loss of blood and oxygen. Also, the procedure takes about an hour, while conventional surgery usually lasts six-to-nine hours. Patients spend several days in recovery, compared with two or three weeks after open-chest surgery.†††††††††††

Many people with thoracic aneurysms are candidates for the catheter approach, according to Hofmann. But the best are those, like Riggleman, who cannot undergo conventional surgery because of pre-existing health problems, previous surgeries, or age. Although the procedure is still being tested, Hofmann expects FDA approval by 2002.†††

Riggleman himself offers the most convincing testimony. Having gone through a number of invasive procedures, "I know what a great thing this is," he says. "In fact, Iíd call it miraculous."

GL

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Expanding a Sunken Chest

Thereís no way that growing up with a sunken chest canít be depressing. Because the chest wall curves sharply inward and presses against the heart and lungs, a child becomes so easily winded that taking part in sports usually becomes problematic. Additionally, the shrunken appearance of the chest and the protruding belly caused by the birth disorder can draw jeers from classmates.

Surgery for the condition, in which the childís breastbone, or sternum, is broken and pushed out to expand the chest wall, has been generally effective in restoring full breathing capacity and correcting an odd-shaped appearance. But occasionally the repositioned sternum either protrudes too far or sinks back requiring another operation. "The chest doesnít look entirely normal in these cases," explains pediatric surgeon Paul Colombani, M.D., "and the chest wall doesnít expand to its full capacity."

Rather than open the chest to expand it, surgeon Paul Colombani inserts a curved stainless steel bar through the two small incisions on the side of the chest (inset).
Rather than open the chest to expand it, surgeon Paul Colombani inserts a curved stainless steel bar through the two small incisions on the side of the chest (inset).

Now, in a new, minimally invasive modification of the surgery, called the Nuss procedure, Colombani and surgeon Charles Paidas, M.D., have reduced the likelihood of such mishaps while improving the patientís appearance. Rather than opening the chest and cracking the sternum, they insert a curved stainless steel bar beneath the sternum through two small incisions on the side of the chest and stitch the bar to the ribs. The bar then pushes the sternum outward and over a two-year period remolds the chest wall. At the end of the process, surgeons slide it out.

"Because nothing has been cut, the likelihood of the chestís falling back down is minimized," Colombani says. "The repair not only is less invasive, but takes less time, so recovery is faster and less painful for children." The Nuss procedure takes 90 minutes compared with the four-hour open surgery.

GL

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Female Incontinence

To understand the connection between prolapse in women and childbirth, gynecologist Geoffrey Cundiff, M.D., suggests we think of the birth canal as a sock. As the baby passes through it, the sockís threads or fibrous connective tissues, which hold the structures of the pelvis in place, are torn away. Over time, as the tissues continue to stretch and tear, pelvic organs like the bladder can protrude into the vagina. The result is pelvic organ prolapse, the leading cause of incontinence in women.

"Stress incontinence is a support problem—loss of support in the bladder neck, the bladder itself or at the top of the vagina," says Cundiff. "Whatís causing this lack of support are hernias. The tissues have torn."

The traditional treatment for the condition has been shortening and reattaching the tissues through abdominal or vaginal surgery. But patients typically spend six weeks at home recovering. Now, Cundiff and his colleagues are offering minimally invasive laparoscopic techniques with less postoperative pain and a shorter recovery time, and equally good results. Through laparoscopic pelvic reconstructive surgery, one of the newest applications of laparoscopic technology, Cundiff has also found a way to fix multiple structural problems in one operation.

In the first step, known as the Burch procedure, Cundiff elevates the sagging bladder neck by suturing it to a ligament on the pubic bone. Next, in a cystocele repair, he stitches to the sidewall of the pelvis connective tissue that supports the bladder itself and which has herniated into the vagina. Similarly, he rebuilds support tissue at the top of the vagina, a procedure known as a† uterosacral suspension. The biggest challenge in performing this three-in-one procedure laparoscopically, says Cundiff, is suturing.

"Most surgeons try to avoid suturing by using mesh and staplers, which sometimes fail. We donít fail because weíre doing a real Burch in the same way you would in an open procedure."

GL

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Detecting Heart Blockage

Putting a patient on a treadmill and then measuring blood pressure, breathing and heart rates is an accepted way for physicians to detect signs of coronary artery disease. But stress testing only picks up blockages that are at least 60 percent obstructive, notes cardiologist Roger Blumenthal, M.D. "By then, the horse is already out of the barn with significant disease of the arteries," and it may be too late to use preventive measures to avoid invasive bypass surgery or angioplasty—expanding the narrowed artery with a balloon. To get around that problem, cardiologists here are using a new type of CT scan, called Electron Beam Tomography, or EBT, that is allowing them for the first time to observe signs of coronary blockages before chest pain and shortness of breath start occurring.

An EBT Scan, says cardiologist Blumenthal, is the first proven, non-invasive way to detect very early development of plaque in the arteries.

An EBT Scan, says cardiologist Blumenthal, is the first proven, non-invasive way to detect very early development of plaque in the arteries.

Blumenthal says that until now thereís been no proven, noninvasive way to see this very early development of plaque in the arteries EBT, which is performed in less than five minutes on a fully clothed patient lying on an open table, works by taking stop-action images of the beating heart, 20 times faster than any previous method. The technique produces images of calcium buildup, which shows up as white specks on the walls of arteries, before these specks develop into calcified plaque. By determining the amount of coronary calcification—the tip of the atherosclerotic iceberg—cardiologists can better predict the personís risk of a cardiac event over the next five years.†

"If indeed you have coronary calcification, you may not have a significant amount of rust, or obstruction, in the pipes," Blumenthal says. "But we can clearly see abnormalities that predict future blockages."

Thatís exactly the information thatís necessary to prescribe preventive treatment to a symptom-free patient and reduce the risk of a debilitating heart attack. About 650,000 of the estimated 1.5 million heart attacks this year, according to the American Heart Association, will be the patientís first indication of coronary artery disease. One in four of those first-time victims will die.

"With a coronary calcium scan, along with a good history, physical and lipid profile and other blood tests, we can determine what an asymptomatic personís risk is with a high degree of certainty," Blumenthal says. "And knowing where they stand may motivate patients to rev up their lifestyle with exercise and diet."

GL

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Diagnosing Cystic Fibrosis

The thick mucus that clogs the lungs in the incurable hereditary disorder cystic fibrosis usually comes to light first during childhood when the patient suffers repeated bouts of bronchitis and sinusitis. But a lot of† patients with these classic symptoms reach adulthood without a physicianís ever connecting them to CF. Itís not hard to understand why: The traditional screen for CF is a sweat test that measures the amount of salt in perspiration—people with the disease canít absorb salt and release abnormally high amounts in their sweat. In a small percentage of those with the disease, however, the sweat test shows nothing.

Now a test available at only a few centers around the country makes the diagnosis unequivocal. Called the nasal potential difference study, it measures the flow of chloride ions into and out of cells controlled by the protein whose deficiency causes CF. "Itís the ultimate test for determining if somebody has cystic fibrosis," says pulmonologist Michael Boyle, M.D.

To administer the painless one-hour test Boyle places electrodes on the lining inside the patientís nose, where the chloride channel is similar to that in the lungs. Then he uses a thin strawlike tube to expose epithelial cells in this lining to chemical solutions to stimulate the chloride channel function. If the chloride channel is turned on by these solutions, as recorded by a small electrical current through the electrodes, the patient doesnít have CF.

Boyle makes clear that this foolproof test is key for any patient who exhibits CF-like symptoms. The earlier the diagnosis, the better the chances of early treatment with antibiotics and anti-inflammatories, slowing the progression of lethal lung damage. Unchecked, the damage will nearly always lead to death or the need for a lung transplant.

"There are treatments that target the various classes of CF," Boyle points out, "but you have to have the diagnosis to know which therapies are best suited for each patient."

GL

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Epilepsy: A Molecular Link

Epilepsy is a complicated disease: Trying to find what sends areas of the brain into apparently spontaneous waves of firing keeps thousands at work in pharmaceutical companies around the world.† Some scientists focus on cellsí producing too much of a stimulatory nerve transmitter. Others say seizures come when something goes awry with the release of an opposing nerve transmitter called GABA (for gamma amino butyric acid)† that normally damps down excitable nerve cells.

But Hopkins neurology researcher Jehuda Sepkuty, Ph.D., offers evidence of still another possible glitch: something may lessen the steady supply of molecules a nerve cell uses to synthesize GABA. The less GABA to quiet target nerve cells, the greater the likelihood of target cells becoming excitable—like taking a restraining hand off a feisty 4-year-old.

Sepkuty suspects the source of the problem is a molecule called EAAC1, which ferries GABAís molecular building blocks into key nerve cells. Once inside the cell, precursor molecules become part of the inhibitory neurotransmitter GABA.†

In the study heís presenting, Sepkuty studied rats genetically engineered to produce less EAAC1.† The rats exhibited episodes of staring and seizures. They also had hyperexcitable limbic systems in the brain—all characteristics of epilepsy.† The ratsí cells also produced less GABA than normal. "We know this is rat epilepsy weíre seeing.†Weíre not sure if this is the human version, though all the signs appear the same—thatís our next investigation," says Sepkuty. "But because this is a completely new approach to what may go awry in some epilepsy patients, it offers us novel sites for drug therapy," adds co-researcher Jeffrey Rothstein, M.D., Ph.D.

GL

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Killing Liver Lesions

When doctors at a major Mid-Atlantic teaching hospital told John Auldridge† last year that his liver cancer was inoperable and nothing more could be done to help him, the 69-year-old Dagsboro, Del., man rushed for a second opinion. He got a better prediction from Hopkins interventional radiologist J.F. Geschwind, M.D., who had helped develop a new way to kill liver tumors through a catheter. Within weeks, four of the five lesions in Auldridgeís liver had been destroyed, and the fifth was scheduled for similar demise.

"This is a patient who had unresectable liver tumors with a life expectancy of six months or less," Geschwind says. "Now heís almost tumor-free."

Interventional Radiologist J.F. Geschwind

Interventional radiologist J.F. Geschwind points to liver lesions that have been killed by a mix of chemo drugs and an oil derived from poppy seeds.

The treatment, called chemoembolization, is a palliative measure—one that has been shown to extend the lives of patients rather than completely cure them. In the procedure, Geschwind feeds a catheter through the femoral artery from the groin to the liver artery that supplies blood to the tumor. He then injects a mix of chemotherapy drugs and an oil derived from poppy seeds that acts as an emulsion to prevent the chemo agents from washing out of the lesions. The formula works both by blocking the blood supply that feeds the tumor and killing cancerous cells within the lesions. Geschwind explains that the chemotherapy is carried to the tumor by the oil, and because the mix is somewhat viscous, it will stay confined to the tumor.

Geschwind uses oil in his mix because Japanese studies have shown that the liver tumor sucks up and accumulates this substance, like a sump pump. At the end of the infusion, Geschwind may also add particles to prevent the chemo drugs from washing out of the liver.

The results? Of this radiologistís patients with inoperable liver tumors, 80 to 88 percent have survived for one year and 60 to 75 percent for three years. Untreated, patients usually die within three to six months of diagnosis. "We were practically in tears," Auldridge said of the procedure. "Any extension of† life is priceless, even if itís just two or three years."

GL

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