While much progress has been made in understanding the causes of Duchenne muscular dystrophy, a cure is still not available. But while there's no cure for muscular dystrophy, its debilitating symptoms can be treated, prolonging mobility, improving quality of life and increasing life expectancy.

Physical medicine is the use of physical therapy and surgery to treat disease. While advances in physical medicine don't get the same attention as those in the areas of drug treatment and gene therapy, there has been some important progress.

Doctors understand better how and when to treat contractures (the permanent tightening of particular muscles), and have developed lightweight and more functional braces. As a result, boys can remain mobile for several years longer than in the past. Surgical techniques have been developed to prevent severe scoliosis, or spine curvature, allowing normal breathing function for many years longer than was the case two decades ago.

In this article, we focus on treatment of contractures. In a subsequent issue of Quest, we'll discuss scoliosis surgery. (See related article.)

MAINTAINING STRENGTH

"The goal of PT and surgery is to keep our boys as strong and functional as possible, for as long as possible," says physical therapist Lynn Wagner of the Muscle Disease Center in Cleveland. "We know that Duchenne dystrophy has a very predictable course; we know our boys are going to get tight heel cords, tight hamstrings, tight iliotibial bands (the muscles along the outside of the thigh that connect the hip and knee), tight elbows. But we also know that proper therapy and surgery at the right time can keep them up and walking longer, and will make it easier to maintain mobility after they begin to use a wheelchair."

As the front calf muscle weakens, the stronger rear calf muscle pulls the heel upward, pointing the toes. Cutting the Achilles tendon prevents permanent contracture.

Contractures begin early: they are found in boys as young as 3, and are seen routinely by age 5 or 6.

Wagner notes that contractures lead to changes in posture. When the heel cords tighten, the feet point downward. Hamstring contractures bend the knees, while iliotibial band contractures turn the legs outward. All of these prevent proper posture and, ultimately, impair mobility. Untreated, contractures can prevent standing, and proper seating in a wheelchair.

Contractures begin with unequal loss of strength in opposing muscles. Muscles are arranged in opposing pairs, one pulling a joint in one direction, the other pulling back. For instance, the biceps muscle on the front of the upper arm bends the arm at the elbow, while the triceps, pulling from behind, straightens the elbow, extending the arm. Before the onset of Duchenne, this pair of muscles is balanced in strength. As the disease progresses, the triceps weakens faster than the biceps, making it difficult to fully extend the arm. As the arm spends more time in a slightly flexed position, the tendon of the biceps, which connects the muscle to the bone, begins to shorten. Unopposed by the weakened triceps, this shortening becomes a permanent contracture.

CHANGES FOR THE WORSE

MDA clinic director Dr. Irwin Siegel of the Rush-Presbyterian St. Luke's Medical Center in Chicago points out that the changes in posture that ultimately lead to contractures may actually begin as important adaptations to muscle weakness.

"The primary problem in Duchenne dystrophy is weak muscles," he emphasizes. "The secondary problems, namely the postural problems and contractures, result from the muscle weakness."

To understand how an adaptation ends up as a debilitating problem, consider the development of heel cord contracture. It begins as an adaptation to weak thigh muscles, whose function is critical for normal walking. When you step forward with your right leg to begin walking, you place your right heel on the ground in front of you, and push off with the left toe to transfer your weight forward. This forward weight transfer pushes the right knee forward; if unopposed, the knee will bend. It's the job of the quadriceps, the "lap" muscle in the front of the thigh, to pull back on the knee to prevent bending. The quadriceps is responsible for pulling the knee into a straight position and locking it there, which allows the left foot to push the body over the rigid right leg. Once this happens, the left leg swings forward, the left heel contacts the ground and the cycle continues.

However, the quadriceps is one of the first muscles to weaken in Duchenne. As a result, straightening and locking the knee becomes progressively harder. To compensate, calf muscle contraction helps lock the knee. However, contraction of the rear calf muscles also causes the foot to point and, as a result, the boy rises up onto his toes, a posture known as "equinus." This chronic contraction of the rear calf muscles, so necessary for maintenance of upright posture, leads to contracture.

Compounding this, the front calf muscles weaken sooner than the muscles at the rear whose actions they oppose. As a result, the rear calf muscles aren't stretched back out naturally as Duchenne progresses, accelerating the contracture.

"Initially, by balancing on the toes, the child is compensating for the muscle weakness," Siegel notes. "Eventually, though, these adaptive changes become a problem. The equinus and the muscle imbalance combine to give contracture of the Achilles tendon; the equinus then becomes fixed, leading to difficulty with standing and walking balance."

PHYSICAL THERAPY

A physical therapist will begin treatment of contracture by evaluating muscle strength, posture and walking gait. For the younger child, the evaluation will consist mainly of observation during play. With the older child, specific activities and tests are designed to quantify range of motion, extent of contracture and any imbalances in movement.

Stretching exercises are then prescribed to counteract contractures before they become deforming. Both Wagner and Siegel stress the importance of beginning early. Once a contracture becomes advanced, it can no longer be corrected by stretching.

"Even in the very young child, there are things we can do," Wagner says. "When a 3-year-old sits in a chair, his feet don't reach the ground and his toes point down. To counteract that, we can design foot rests at the right height to maintain the foot in the correct position."

In the slightly older child, a series of daily stretching exercises performed by the family act to maintain the flexibility that weakened muscles can no longer provide. By continuing to stretch out the muscles prone to shortening, contracture can be delayed.

The exercises prescribed are passive stretches, meaning the child doesn't use his own muscular strength to do the stretching. Over- stretching, in particular, must be avoided. An over-stretched muscle responds by developing more strength and contracting further, exactly the opposite of the desired effect. Also, exertion of opposing force by the boy while the muscle is being stretched is discouraged. This kind of activity, called a lengthening contraction, may damage the weakened muscle fibers further.

To stretch the heel cord, the boy lies on his back with his leg extended. The person doing the stretching doesn't simply push against the balls of the feet; this would stretch the muscles along the length of the foot. Instead, a special grip designed to stretch only the Achilles tendon is used. Wagner stresses that proper technique is critical, and should be learned from the physical therapist.

"We have the family show us every few months how they are doing the stretches, so we can modify their technique if we need to," she says.

A typical course of stretches will take between 20 and 40 minutes per day.

Are they painful? No, says Billy Bedford of Akron, Ohio, one of Wagner's patients. "There is occasionally some discomfort, but I never avoid them because of that."

In fact, most boys look forward to the stretching sessions, as Billy does. Brenda Guinto of Brunswick Hills, Ohio, says her son Adam "insists we do the whole course of stretches. He feels better afterward, both physically and psychologically. And if we have to miss a day, he feels it the next day: he's a little tighter, a little less comfortable."

BUILDING A BOND

For many families, these exercises are at least as important for their psychological benefit as they are for delaying contractures. Parent and child, and even siblings who may help out, find the daily ritual strengthens the emotional ties within the family. Both families also mentioned that the long-term relationship they developed with the physical therapy team has been extremely important to them.

"It's a really special relationship," says Kathy Bedford, whose two boys grew up with the team at Cleveland's Muscle Disease Center.

Strengthening exercises are often not included in the physical therapy program for Duchenne boys. While opinions vary on this, many doctors feel that the extra work on the muscles induces damage rather than protecting a muscle or compensating for its weakness. But, normal daily activity is vital: keeping the joints moving is the key to preventing contractures.

"We believe that being involved in regular daily activities provides about as much strengthening as is necessary," Wagner says.

How much is enough? This differs for each person, but standing or walking for at least several hours a day provides a level of activity suitable for boys in the early stages of Duchenne. With too little activity, muscles become weakened through disuse, and contractures have a chance to accelerate. With too much activity, muscles fatigue.

"If a boy is waking up tired," Wagner says, "he probably is doing too much. While fatigue at the end of the day is normal, a good night's sleep should be sufficient to restore his energy." She adds that contractures can interfere with nighttime comfort, so stretching them provides a benefit here as well.

Sometimes a physical therapist will prescribe night splints, to keep the heel cords from tightening overnight. When the boy can tolerate them, they may be effective. However, many therapists recognize that discomfort will eventually lead patients to abandon them.

Sleeping on the stomach, with toes dangling, can keep feet out of the equinus position, and helps to prevent hip contractures as well. This position is also used for lying on the floor to read, play games or watch television, with pillows used for proper elevation of the ankles.

Heel cord contractures usually develop earliest, followed by contractures in the upper legs. Later, the upper limbs may be affected, although, until recently, not as much attention has been given to them. Wagner has been studying contractures in the arms and hands for more than a decade.

"It struck me early in my career that the one thing the older boys can still use is their hands, because they still have strength in those muscles. However, they often have contractures of the hands and wrists, which prevent them from using them fully. So we decided we needed to provide treatment for that."

Wagner prescribes night splints for the hands and wrists when contractures begin to develop, as well as stretching. The splints are usually worn on the left hand one night, then the right hand the next, to avoid too much discomfort. "I've been impressed with the results," she says. Adam, 15, plays the keyboard with the aid of an assistive device attached to his wheelchair. At 25, Billy continues to work at his computer, helping his father with graphic arts retouching.

SURGERY HAS ITS PLACE

While early and conscientious physical therapy will delay the onset of contractures, it can't prevent them in Duchenne. The falling activity level due to progressive muscle weakness and the unequal rate of weakening between paired muscles combine to ensure that eventually contractures will set in. Fear of falling is another factor in the acceleration of contractures: The loss of confidence in his stability may keep a boy from being up and about as often as his strength would allow him. This sets up a spiral of decline, as less activity leads to more contracture. This, in turn, leads to more precarious balance and less activity. When this stage in the development of contractures is reached, doctors recommend surgery to release them, followed by bracing of the limbs.

"Contracture release surgery has several goals," Siegel says. "First, we can expect it to provide between two and five extra years of mobility. After that, the braces allow standing for many years, plus more comfortable seating in the wheelchair, and easier transfers in and out of it."

BOUNCING BACK

Siegel stresses that both the release surgery and the braces are necessary for attaining those goals. Without the surgery, the braces can't be properly fitted and, without the braces, the contractures will return after the surgery.

The operation, done under general anesthesia, is quite simple, and lasts less than an hour. The anesthesiologist will take special precautions before and during surgery to monitor levels of certain substances in the blood, in order to prevent complications that are more common in Duchenne than in other diseases.

A KAFO, or knee-ankle-foot orthosis.

"This is not something to be done without the proper facilities to manage it," Siegel says. But, he adds, with proper attention to anesthesia, contracture release surgery is routine and quite safe.

During the operation, the surgeon makes a small incision near the contracted tendon, then reaches in with a scalpel to cut it.

The actual surgery may take as little as two minutes. There is very little blood loss, and suturing, or stitching, is rarely needed. Occasionally braces can be fitted before the operation; if so, they are applied immediately. If not, plaster casts are applied to keep the leg in the proper position. If the boy has been on steroid medications, extra doses may be prescribed before, during and after the operation. According to Siegel, pain is minimal, and is usually managed with a non-prescription analgesic. The surgery can be done on an outpatient basis.

Siegel stresses how important it is for the boy to be up and about right away. "We lose strength at a rate of about 2 percent to 5 percent per day for each day of immobility. If we lose too much, we may not get it back." For this reason, the physical therapist works with the boy to get him up on his feet within hours of the surgery, and to increase activity quickly.

BRACES AND STANDING TABLES

Measuring for braces usually occurs 10 days after the surgery, and they're ready to wear 10 days after that. They're worn day and night for three to six weeks while the tendon heals, then daily. The braces, made of a strong, lightweight plastic, fit inside normal shoes or sneakers and underneath normal pant legs. The braces run from above the knee to the ankle and foot. They have a locking hinge at the knee, allowing the leg to be either bent or straight.

Brenda Guinto says, "Adam loves them. He wants to wear them all the time." The braces stabilize the joints in the legs to allow more confident walking, and maintain the joints in the proper position to prevent reoccurrence of the contractures. Even after walking becomes too difficult, daily standing remains possible for many years with the aid of braces and a standing table.

A standing table is a device that allows a youth with Duchenne to stand comfortably and safely. The table, which is like a podium with a rear door, gives support and stability while promoting good posture.

As walking becomes more difficult, it's easy to spend large amounts of time sitting, with knee and hip joints bent. This reinforces the contractures that form at those joints. Daily standing stretches these joints and burns more calories than sitting.

Tables are especially helpful at school, where the alternative is prolonged sitting in the classroom. In this context, Wagner notes, the relationship of the boy to his school can be one of the most important to the success of the physical therapy program.

"The ones who do the best are the ones in a supportive school environment," she says. She points out that the construction of a standing table can make a great project for classmates in shop class, which is how Adam Guinto came by his. Billy Bedford still stands daily at his table. He uses a hydraulic model which lifts him from a sitting position. It also has wheels, and so moves easily from inside the house onto the porch.

Siegel is developing a brace that can delay the need for heel cord release by stimulating the reflexes which normally stretch out the Achilles tendon. It's designed with an opening at the heel, so that sensory nerves in this area remain stimulated, while the brace reduces sensation in other areas of the foot.

"If you imagine what happens when someone tickles your heel, you realize that stimulating this area causes the toes to come up, stretching out the heel cord," he says. "This is exactly the movement we want to encourage."

While the brace is still being tested, Siegel is encouraged by the results he's seen so far.