Monday, December 9, 2013
It’s expected that the frozen tundra that is Lambeau Field would host cold weather NFL games in the middle of December, but that scenario was also true in Philadelphia, Denver, Pittsburgh and Chicago where snow, ice and single temperatures welcomed not only the players but tens of thousands of fans. The decision to play in frigid weather might be a variant of “the show must go on”, but for fans to choose the cold of an outdoor stadium, instead of watching the game on television in a warm house seems somewhat questionable. Is hypothermia and frostbite worth the collective game experience?
The body functions quite poorly as it chills, and for that reason, there are a variety of mechanisms built in to maintain body heat. Normally, body temperature is regulated by the hypothalamus in the brain and heat is generated by cell metabolism, mostly in the liver and heart. When the body starts to chill, the brain tells the body to ramp up heat production by muscle shivering (up to 5 times more than baseline). But in cold environments, shivering may not be enough to keep the body warm. It take significant energy for all that muscle work and glycogen stores within muscle cells can be depleted, a process no different than running out of energy after exercising. The brain can put the body into survival mode and starts to shunt blood from the skin, where it can be cooled by exposure to the cold environment, and pushes is toward the body’s core, trying to keep vital organs like the heart, lung, intestines and brain warm.
Unfortunately, the shunting of blood away from the skin, especially to the far reaches of the body in the fingers, toes, nose and ears, increases the potential that frostbite will occur. Ice crystals can form in the interstitial spaces between cells. Cell damage can occur either from these ice crystals, directly from the cold and from sludging of blood in the small blood vessels. When skin temperature drops to 60F, blood flow drops to 10% of normal. When it gets to freezing (32F), blood flow stops. In between, blood occasionally pulses to try to maintain some semblance of circulation but may or may not be successful.
For those who have lived in a northern climate, the symptoms of frostbite are well recognized; cold, stinging and throbbing is followed by intense pain when the area is rewarmed. With increasing severity of frostbite, there is numbness followed by complete loss of sensation and difficulty with dexterity and function. Frostbite is classified similarly to thermal burns depending the appearance of the skin and it may take time to appreciate the amount and depth of frostbite injury. White skin with surrounding redness signals a first degree injury. Over time, if skin starts to blister, it may be a sign of deeper second degree injury. Third degree frostbite may take a couple of weeks to become apparent with full thickness skin injury and gangrene formation.
While frostbite is not good, hypothermia is even worse. As the body loses its ability to compensate for the increased heat loss in a cold environment, organs begin to slow down. Electrical activity also is affected and victims can become lethargic and confused. Interestingly, patients develop paradoxical undressing, where clothes are shed even in the coldest weather. Heart electrical conduction can be affected and as the body cools, the regular rate and rhythm may degenerate into unstable patterns like ventricular fibrillation that cannot sustain life.
The body is able to adapt to the cold but not as well as it can adapt to heat. Fortunately by wearing layers of clothes, staying active and keeping dry, heat loss can be minimized. Unfortunately, alcohol and drugs can affected the body’s ability to conserve heat. Most often, the best treatment for preventing hypothermia and frostbite is prevention. The players had reason for being outside in the bitter cold doing their job, but we can only presume that the fans were in the stands because of their love for the game, not for the sanity of their decision.This entry was tagged cold, frostbite, hypothermia
Monday, December 2, 2013
Packer Nation and all of Wisconsin have all become experts on bone healing, giving their opinions as to when favorite son, Aaron Rodgers should return to play quarterback after fracturing his clavicle and thus resurrect the failing Green Bay team. If only it was so easy to know when a bone has completely healed. Though most athletes who break their collarbone and return to play within a couple of months, the notion that the bone has completely healed is faulty. While the bone may have regained its strength, healing as defined by x-ray may take 4-6 months and final remodeling and sculpting can take years.
The question is: when can a player or a construction worker or a kid return to their activity and not have an increased risk of reinjuring the same bone, understanding that given the same set of circumstances that caused the fracture in the first place, the bone will still break.
Bone healing is a long physiologic process and the body can fix most fractures by itself. Doctors get involved to try prevent complications, keep bones in alignment and return to the body to function as soon as possible. There are a variety of stages in bone healing and they cannot be rushed.
The first stage is reactive. A blood clot forms at the area of the fracture (remember that fracture, break and crack all mean the same thing, that the integrity of the bone has been compromised) and begins the healing process. Though this clot will eventually dissolve and the cells within it die, it allows the formation of granulation tissue or the matrix that will form the scaffolding for new bone formation. Fibroblasts from each broken end start forming collagen, the body’s building blocks that begin to span the space between the broken edges.
Reparative stage happens next. At the broken bone edges, the outer lining called the periosteum gets turned on, generating chondroblasts that make cartilage and osteoblasts that make bone. They form a mix of bone and cartilage that is not well organized called woven bone and has little strength. However, this mass of bone at the fracture site allows for the real magic of healing to occur. The surface of the callus starts to be pitted by small blood vessels and many more osteoblasts. Instead of laying down random woven bone cells, more formal bony patterns develop into lamellar or cortical bone. This bone is trabecular, meaning that there is a lattice work of bony beams and crossbeams to maintain strength and shape.
The last stage is remodeling, where the body takes the extra amount of bone that has been laid down at the fracture site and slowly sculpts it back closer to its original shape. The trabecular bone is gradually replaced by compact bone in a process that can take up to 5 years. Osteoclasts, cells that break down bone, and osteoblasts, the bone makers, work together during this process.
The wider the gap between the bone edges, the longer the process takes to complete. For that treason, many fractures that had once been allowed to heal on their own are now being considered for surgery. The clavicle or collarbone has been studied extensively since it is so often injured. For displaced fractures where the bones edges are moved apart, surgical repair (also called ORIF for open reduction and internal fixation), seems to have better results than just allowing to have the bone heal on its own. Aside from showing healing more quickly by x-ray, almost 12 weeks faster, patients who had an operation had better function and were happier with the cosmetic result.
Mr. Rodgers had a non-displaced clavicle fracture and needed no surgery, but the healing that needs to occur is still the same and cannot be rushed. When the decision is made to allow him to play and should the bone not have gained enough support and strength to withstand injury, there is the risk that the bone will break again at the same spot.
Aside from clinical judgment by the patient and physician, there is no test to know precisely when the bone is physiologically healed. The clavicle will take many months to heal by x-ray but x-rays usually lag behind the clinical situation. The coach doesn’t know, the sportswriters don’t know and most certainly, Packer Nation doesn’t know. Mr. Rodgers will be cleared to play when the doctor’s gestalt, gut feeling and experience say that he’s ready to go. Meanwhile, Wisconsin can’t wait.
This entry was tagged Aaron Rodgers, bone healing, clavicle, collarbone, fracture, green bay packers
Dr. Wedro weighs in
“The difference between doctors who look after mere mortals and those who look after elite athletes may have to do with how many tests they can order, regardless of the cost.”