The winter Olympics serve as a showcase for some of the finest athletes in the world. Many of the winter events involve sports that are unusually demanding on the human body. Take the case of Evegeni Plushenko, the Russian hope for gold in men’s figure skating.
The Russian men’s and women’s teams have long been a dominant force in figure skating and the decision was made to go with Plushenko despite the fact that he was considered quite old at age 31. The Russians hoped his long experience at 4 Olympic games and multiple medal wins would put him in position to win again even after undergoing painful surgery to replace a disc in his back with a synthetic one. Plushenko’s final chance at glory was cut short when he was forced to withdraw from Olympic competition due to the pain of years of injuries finally catching up with him.
While career ending injuries can happen in many winter events, ice skating takes a particular toll on the bodies of participants. Years of practicing jumps and the occasional fall to the ice can cause damage to bones and especially joints. Researchers at the University of Delaware attached tibial accelerometers to skaters and measured the impacts of jumps as high as 100 G’s. The researchers noted that skaters have high incidence of stress fractures, knee injuries and hip problems. Olympic champion Tara Lipinski had hip surgery at age 18.The goal of this research is to help the athletes develop just the right technique to use muscles in a way as to reduce the shock imparted to bones and joints. The use of motion capture technology assists with this aspect of training.
Another area where science helps these athletes involves measuring fat and muscle composition. Strength training that causes an increase in girth at the shoulder or thighs will decrease rotational spin, a dramatic part of the demonstration of skating ability so important to judges. Also, bone density measurements indicate likelihood of stress fractures or joint damage. Low bone density makes one prone to stress fractures or breaks. On the other end of the scale, when bone is repeatedly stressed, it tends to thicken. High bone density may increase pressure on the joints leading to damage and inflammation.
Bone tissue is a complex and ever changing combination of extracellular matrix where various cells interact to maintain its strength. Bone cells perform different functions within this tissue. Osteoblasts create new bone matrix and Osteoclasts break down bone tissues. Other cells called Osteocytes help maintain healthy bone tissue. The growing bones of youth increase in length and girth simultaneously. Cells called Chondrocytes produce cartilage which the Osteoblasts turn into hard bone tissue through calcification, the addition of minerals like calcium and phosphorous. At the ends of growing long bones, like the femur, plates of cartilage called growth plates are responsible for the lengthening of bones. Osteoblasts are also active on the outside of growing bone which causes an increase in diameter. One has to be careful with youth sports, particularly those that include impacts (like practicing jumps in ice skating) to joints and the ends of bones so that the growth plates do not become damaged. This can cause long term development problems in those impacted bones.
Even in an adult, repeated impacts to bone tissue can lead to damage. The most severe result of a heavy impact is a broken bone which requires a cast to immobilize the bone until it can repair itself. But even less severe impacts can cause damage if repeated over time. Stress fractures result from repeated impacts to a bone. The force may not be enough to cause a break but rather to crack. The damage can be evidenced by signs of the bone attempting to heal.
Broken and damaged bone is ultimately repaired by the process of bone remodeling. This process also takes place in healthy, intact bone in order to maintain normal strength and to replace portions of bone as we age. Calcium homeostasis requires that bone cells deposit extra calcium in bone tissue to later release it when blood calcium levels drop. As a result both osteoblasts and osteoclasts are active in removing and then adding new bone tissue throughout the length of any bone. As part of this normal remodeling process, any damage to bones will eventually be repaired over time.
In cases where there is no outright damage to the bone itself, the protective covering at the end of bones, where they meet at a joint, can also become damaged. Locations where bones meet are called joints. Some joints do not allow any movement at all while other joints have a high degree of movement. There are many joints in each hand and each foot for example. The knee and elbow and shoulder and hip are all joints with a high degree of movement. The joints of the lower extremities are particularly susceptible to damage from overuse because they bear the weight of the entire body. Actions like performing jumps in skating take a toll on the ankles, knees and hips. Even the bones of the spine are subject to damage due to repeated impacts.
All of these main joints have bones coming into contact with each other. To prevent the bones from scraping as they move, the bones are covered at the end by a pad of cartilage. When athletes train, they practice the same movements over and over and over to achieve perfection. However, all this repetition can wear down the protective cartilage resulting in a form of arthritis, which is a term for inflammation of the joint. In this case the wearing down of cartilage is called osteoarthritis.
Everyone develops some degree of osteoarthritis as we age. By the time we get into our 70’s or 80’s most people will develop osteoarthritis in at least one joint. Activities that increase the wear and tear on joints can accelerate the process. Athletes, dancers or even construction workers can accelerate the pace at which cartilage wears down in joints, particularly weight bearing joints like the knees or hip joints and the lower spinal vertebrae. Obesity also contributes as a major risk factor for developing osteoarthritis as extra weight increases the strain on load bearing joints. Eventually the protective cartilage layer wears down and portions of bone become exposed and may rub and scrape against other bones in the joint. The result is pain and inflammation. Medication can treat symptoms but the underlying problem, lack of protective cartilage cannot be undone. Eventually the only recourse is to replace the joint itself.
The most common cause of hip replacement surgery is osteoarthritis. When the damage becomes too severe and the pain interferes with mobility, doctors may opt to replace the worn out bone and cartilage with metallic or ceramic parts. Once reserved for patients over 60, younger people with a need for joint replacement are finding it can improve their quality of life. Since younger people now receive joint replacement, some patients required a replacement of the original implant after 15-20 years as they wear down.
There was an interesting case recently where one patient had a host of cardiovascular symptoms what doctors could not resolve. After many physicians were unable to find the problem, one remembered an episode of the TV show House where the doctor (played by Hugh Laurie) diagnosed a similar problem as cobalt poisoning.
It turns out the patient had a ceramic hip implant recently replaced with a metal one containing cobalt. While normally inert, some ceramic particles from the original implant were left behind which then abraded the surface of the metal joint, releasing cobalt into the bloodstream. Once the joint was repaired the patient made a recovery.
Not all injuries on the ice are related to bone tissue. As with many sports, muscle injuries are common on an ice rink, particularly in ice hockey. While figure skating involves speed and jumps and rotations, the main characteristic is smooth gliding; it’s ballet on ice. Hockey on the other hand requires a different type of skating. Here, one will see speed and heavy impacts but players also come to a stop, change directions and sprint away. Aside from the obvious damage inflicted by one player crashing headlong into another player, the quick changes of direction can lead to muscle pulls and groin injuries. The blades of skates for figure skating are made a little differently than hockey blades. Improperly sharpened skates can provide too much traction on the ice and cause a hockey player to pull a muscle trying to suddenly change directions. There appears to be an art to properly sharpening ice skates to fit the particular sport.
Contributed by Michael Troyan. Michael has spent 20 years teaching non-majors biology and microbiology and currently works as an online instructor at Penn State University. He can be reached at [email protected]
- Dahms K., Sharkova Y., Heitland P., Pankuweit S. & Schaefer J.R. (2014). Cobalt intoxication diagnosed with the help of Dr House, The Lancet, 383 (9916) 574. DOI: 10.1016/S0140-6736(14)60037-4
Are you a science educator who is interested in contributing to RicochetScience?
If so, then please contact us for more information.