how muscles heal

Monday, July 27, 2015

This weekend, a friend self diagnosed a hamstring tear after feeling a pop and developing searing pain in the back of his leg, while sprinting at a family picnic. He joined Dustin Pedroia of the Boston Red Sox, who was placed on the disabled list this weekend with the same injury. It’s a reminder that weekend warriors and elite athletes share the same potential for pushing their bodies to the point of self-harm. The bad news is that the hamstring muscle group takes forever to heal and one cannot rush Mother Nature.

The hamstring is really a group of three muscles, the semimembranosus, the semitendinosus and the bicep femoris, that is responsible for flexing the knee. The muscles and their tendons attach to bones in the pelvis and then span the knee to attach into the tibia. When the muscles contract, the knee flexes; as well, they have another job to provide dynamic stability to the knee as it extends, when the quadriceps muscle on the front of the leg contracts. The two muscle groups need to be in balance, so that one group does not overpower the other.

Hamstring injuries occur when the muscle is aggressively stretched while running or jumping; it is usually not a contact injury. The injury is technically a strain and can occur within the muscle belly, within the tendon, at the junction where muscle turns into tendon or the damage can occur where the tendon or muscle attaches to bone and part of the one is avulsed or torn away. Grade one strains mean that the muscle fibers are stretched and not torn. Grad two strains mean that there is a partial tear of the muscle and grade three equals a complete tear.

Hamstring injuries take forever to heal…not quite literally forever, but often the time frame is measured by months and not days or weeks. The clinical healing is pretty straightforward, with pain and range of motion guiding how much the patient is allowed to do. It’s the stuff that happens at the cellular level that can help explain why rehab takes so long.

When a muscle tears, the injury and repair mechanism kicks into high gear. There are three phases of muscle repair. Initially, there is an inflammatory phase that last a few days, where the body sends in its scavenger cells that clean up the dead muscle fibers. These white blood cells (including leukocytes, monocytes and macrophages) are also responsible for sending chemical signals to activate growth factors that regenerate the broken muscle fibers. This begins the repair phase that will take 3-4 weeks to complete. The ruptured ends of the muscle begin to fuse by having scaffolding built by connective tissue that can bridge the gap and allow scar to form. This scar will hold the muscle together for the remodeling phase, where new muscle fibers and cells invade the scar tissue and ultimately replace it with functioning muscle. It takes 3 to 6 months. The healing process can sometimes derails and deposit excess scar tissue. This can limit the range of motion of the muscle and in turn make it weaker and more prone to injury. No matter how much the brain is willing to participate in rehabilitation, the cells can only work so fast.

Predicting how long it takes to return to play is an inexact science. A few studies have tried to help with the guesstimate. One group of athletes, who were able to walk without pain within a day, were able to return to play more quickly; otherwise, it was a minimum of three weeks away from their sport. Another study found that if significant pain were present for three days after injury, the recovery time would last more than 6 weeks. And finally, athletes who did not completely tear their hamstring and were able to retain their flexibility could expect to return to play within five weeks; unless they had had a previous hamstring injury and then their prognosis was not as good.

Elite athletes measure the length of their career, and more than a few weeks off can mean a season lost. A too early return to play can lead to potential recurrent injury, because the muscle remains weak and/or flexibility has not returned to normal. If the injury was caused because of poor biomechanics, the risk of another injury remains because the underlying condition was not addressed.

There is a balance in physical therapy and rehabilitation. Moving an injured muscle early on, promotes muscle fibers to regenerate and speed healing, but too much activity can lead to a larger scar and the risk of re-tearing the not quite healed muscle. Not enough activity will cause the muscle to atrophy or waste away, and perhaps be replaced with too much. This delays the ability to rehabilitate the muscle and restore strength. It is the art of the physical therapist that helps find the Goldilocks pace of rehab… not too fast, not too slow, but just the right speed.

As it turns out, my friend who was injured in his backyard, and Dustin Pedroia, injured at Fenway, will heal at the same rate so long as they listen to their body. The only difference? My friend will go to work and think of physical therapy in passing. Mr. Pedroia will go to work each day and there will think of nothing but physical therapy and getting his leg ready to return the basepaths.

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the risk of decision making

Monday, July 13, 2015

There is a joy to be found in numbers and many sports fans have translated their appreciation of statistics to the level of passion because of fantasy sport leagues. The concept is simple. Managers and coaches devise on-field strategy based on their expectation of how the past might predict the future, and bettors rely on the same thought process. As it turns out, medicine works the same way, but the stakes may be a little higher.

A good example might be the approach to the patient with chest pain. While appreciating that there are many serious diseases and illnesses that can cause chest pain, pressure or tightness, most people and doctors worry about heart disease. The heart is a muscle and like any other muscle in the body, requires arteries to deliver oxygen and nutrients. If plaque and calcium narrow those arteries, a patient might experience symptoms during exercise or work or even walking upstairs. This is called angina and it may not be pain, but could be pressure or tightness of indigestion or perhaps nothing more than n indigestion or mild shortness of breath. If a plaque ruptures and a blood clot forms to completely block the artery, the section of heart muscle that it supplies will die if the blood flow is not re-established quickly. This is called a myocardial infarction or heart attack.

When a patient presents with chest pain to the ER, as protocol, the nursing staff may do an EKG, even before a doctor sees the patient. That EKG may diagnose the acute heart attack and the patient will head off to the cath lab to have a cardiologist open the blocked artery. But if the EKG isn’t exciting, it’s up to the doctor to decide whether to proceed down the “is it the heart?” pathway. Sometimes, clinical judgment says that the pain is coming from the esophagus, or lung or chest wall and no further heart testing is needed; but if the symptoms are suspicious and risk factors are present (smoking, high blood pressure, high cholesterol, diabetes and family history), more needs to be done.

Heart muscle that is irritated can leak a chemical, called troponin that can be measured in the blood. It takes a couple of hours or more for that test to turn positive, so an initial normal troponin is heartening but not necessarily conclusive. It means that no heart damage has yet been uncovered but a repeat test may be worthwhile.

A normal EKG and normal blood test means looking back in time that no heart damage has occurred, but does that mean that the heart arteries aren’t partially blocked? Is there a possibility of a heart attack in the near future? What do the statistics say about predicting the future and how low does the risk have to be before the patient and the doctor are happy?

The American Heart Association recommends that patients with chest pain, who are found not to have heart damage, should have their heart imaged in some way, within 72 hours of their visit. That imaging could be a stress test while walking on a treadmill, a radioactive dye injected to show blood flow to the heart, an echocardiogram (ultrasound of the heart), a cardiac CT or the gold standard and most invasive test, a cardiac catheterization. Each has its indications and place in the risk stratification of the patient, but the decision as to which test to order has some art mixed in with the science. All these tests are not cheap and requires a fair amount of technology, and may not readily be available.

Or the patient can assume some risk. There have been research and studies that have tried to put a number to that risk. In one group  of patients who wee followed whose chest pain story was slightly or not suspicious for heart disease, who were younger and also had normal EKG and blood tests, the chance of having a major adverse heart issue within six weeks, was 1.7%. This number could drop to below 1%, if the patient were watched for a longer time frame and more blood tests done, but theirs never became zero.

Many patients and their families would accept a risk of less than 2%, meaning that more than 98 times out of 100, their heart was healthy. But the numbers also need to be looked at from the doctor and hospital perspective. A busy hospital ER might see a hundred or more chest pain patients each week. That less than 2% risk could add up to hundreds of missed heart attacks a year… not very acceptable numbers. While the Heart Association guidelines may be too strict, others may be too lenient and that is where clinical judgment, practical experience and common sense come into play.

Statistics may help drive strategy, but a manager’s gut feeling or game savvy may suggest a road less travelled when shifting fielder or changing pitchers. The art of medicine uses the same intuition to help guide the doctor and the patient to decide which plan of action is appropriate for one particular situation at one particular time. In medicine, statistics are fine for the general population, but when a complication happens, it happens 100% of the time to that patient. The goal of medicine is to maximize care, minimize risk and use resources wisely… and for that reason, doctors could learn a thing or two from managers, coaches and fantasy draft junkies.

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