Patellofemoral pain syndrome Runners Knee

From professional athletes to weekend warriors, the condition known as "runner's knee" is a painful and potentially debilitating injury suffered by millions of people - although until now, it has been unclear just what causes it.

But new research from the University of North Carolina at Chapel Hill has zeroed in on what appear to be the main culprits of the condition, formally known as patellofemoral pain syndrome.

The study is believed to be the first large, long-term project to track athletes from before they developed runner's knee, said study co-author Darin Padua, Ph.D., associate professor of exercise and sport science in the UNC College of Arts and Sciences.

"Earlier studies have usually looked at people after the problem sets in," Padua said. "That means that while previous research has identified possible risk factors related to strength and biomechanics, it's been unclear whether those caused the injury, or whether people's muscles and the way they moved changed in response to their injury."

The research appears in the November issue of the American Journal of Sports Medicine.

Runner's knee - the bane of many types of exercise, from running to basketball to dance - affects one in four physically active people. If unchecked, it can lead to more serious problems such as patellofemoral osteoarthristis.

"Patellofemoral pain syndrome can be devastating," said Padua. "The pain can severely curtail a person's ability to exercise and the symptoms commonly reoccur. That said, athletes often have a high pain threshold and may ignore it. But if they do, their cartilage may break down - and if that gets to the point of bone on bone contact, nothing can be done to replace the damaged cartilage."

Padua and his colleagues studied almost 1,600 midshipmen from the United States Naval Academy. Researchers analyzed participants' biomechanics when they first enrolled at the academy, then followed them for several years to see if they developed patellofemoral pain syndrome.

A total of 40 participants (24 women and 16 men) developed the syndrome during the follow-up period. The study found:

- Participants with weaker hamstring muscles were 2.9 times more likely to develop the syndrome that those with the strongest hamstrings
- Those with weaker quadriceps muscles were 5.5 times more likely
- Those with a larger navicular drop (a measure of arch flattening when bearing weight) were 3.4 times more likely
- Participants with smaller knee flexion angle (those whose knees bent less on landing during a jump test) were 3.1 times more likely

Padua said the pain associated with the condition could be explained by those different factors coming together to create a focal point of pressure between the kneecap and the underlying bone.

"Overall, these people generally have weaker quads and hamstrings. As a result, they don't bend their knees as much when doing task, such as running or jumping. That means the contact area between the kneecap and the femur is smaller, so pressure is focused and pinpointed on a smaller area.

"Also, the more a person's arch falls when bearing weight, the more their whole leg may rotate inwards. That will mean their kneecap won't track properly, leading to yet more pressure and more potential pain."

Padua said the good news is that the study appears to confirm that if people can change the way they move and improve their leg strength, they can prevent or correct the problem.

Everyday athletes can also spot for themselves whether they are at risk: if their knee crosses over the big toe when squatting; the arches of their feet collapse when landing from a jump; and if they do not bend their knees much when they land, they stand a greater chance of developing the syndrome, Padua said.

The researchers are now looking into which exercises are best for improving the biomechanics involved. They have also developed a simple screening tool, called LESS (Landing Error Scoring System), for identifying people most at risk of runner's knee and similar conditions, and of suffering ACL (anterior cruciate ligament) injuries.

The study's lead author was Michelle C. Boling, Ph.D., a UNC doctoral student at the time of the study, now an assistant professor at the University of North Florida, Jacksonville, Florida. Other co-authors are Kevin Guskiewicz, Ph.D., professor and chair of the UNC exercise and sport science department; Stephen W. Marshall, Ph.D., associate professor of exercise and sport science, and of epidemiology and orthopedics in the UNC Gillings School of Global Public Health and the UNC School of Medicine, respectively; Scott Pyne, M.D, United States Naval Academy, Annapolis, Md.; and Anthony Beutler, M.D, Uniformed Services University of the Health Sciences, Bethesda, Md.

Source
University of North Carolina at Chapel Hill

Running Shoes

Here's a great article featured on http://www.acatoday.org/

How to Select Athletic Shoes

Too many people choose fashion over function when purchasing athletic shoes, not realizing that poor-fitting shoes can lead to pain throughout the body. Because footwear plays such an important role in the function of bones and joints—especially for runners and other athletes—choosing the right shoe can help prevent pain in your back, hips, knees, and feet.
Unfortunately, there is no such thing as the very best athletic shoe—every pair of feet is different, every shoe has different features, and overall comfort is a very personal decision. For this reason, it is recommended that you first determine your foot type: normal, flat, or high-arched.

The Normal Foot:
Normal feet have a normal-sized arch and will leave a wet footprint that has a flare, but shows the forefoot and heel connected by a broad band. A normal foot lands on the outside of the heel and rolls slightly inward to absorb shock.

Best shoes: Stability shoes with a slightly curved shape.

The Flat Foot:
This type of foot has a low arch and leaves a print that looks like the whole sole of the foot. It usually indicates an over-pronated foot—one that strikes on the outside of the heel and rolls excessively inward (pronates). Over time, this can cause overuse injuries.

Best shoes: Motion-control shoes or high-stability shoes with firm midsoles. These shoes should be fairly resistant to twisting or bending. Stay away from highly cushioned, highly curved shoes, which lack stability features.

The High-Arched Foot:
The high-arched foot leaves a print showing a very narrow band—or no band at all—between the forefoot and the heel. A curved, highly arched foot is generally supinated or under-pronated. Because the foot doesn’t pronate enough, usually it’s not an effective shock absorber.

Best shoes: Cushioned shoes with plenty of flexibility to encourage foot motion. Stay away from motion-control or stability shoes, which reduce foot mobility.

When determining your foot type, consult with your doctor of chiropractic. He or she can help determine your specific foot type, assess your gait, and then suggest the best shoe match.

Shoe Purchasing Tips
Consider the following tips before you purchase your next pair of athletic shoes:

• Match the shoe to the activity. Select a shoe specific for the sport in which you will participate. Running shoes are primarily made to absorb shock as the heel strikes the ground. In contrast, tennis shoes provide more side-to-side stability. Walking shoes allow the foot to roll and push off naturally during walking, and they usually have a fairly rigid arch, a well-cushioned sole, and a stiff heel support for stability.

• If possible, shop at a specialty store. It’s best to shop at a store that specializes in athletic shoes. Employees at these stores are often trained to recommend a shoe that best matches your foot type (shown above) and stride pattern.

• Shop late in the day. If possible, shop for shoes at the end of the day or after a workout when your feet are generally at their largest. Wear the type of socks you usually wear during exercise, and if you use orthotic devices for postural support, make sure you wear them when trying on shoes.

• Have your feet measured every time. It’s important to have the length and width of both feet measured every time you shop for shoes, since foot size often changes with age and most people have 1 foot that is larger than the other. Also, many podiatrists suggest that you measure your foot while standing in a weight bearing position because the foot elongates and flattens when you stand, affecting the measurement and the fit of the shoe.

• Make sure the shoe fits correctly. Choose shoes for their fit, not by the size you’ve worn in the past. The shoe should fit with an index finger’s width between the end of the shoe and the longest toe. The toe box should have adequate room and not feel tight. The heel of your foot should fit snugly against the back of the shoe without sliding up or down as you walk or run. If possible, keep the shoe on for 10 minutes to make sure it remains comfortable.

How Long Do Shoes Last?
Once you have purchased a pair of athletic shoes, don’t run them into the ground. While estimates vary as to when the best time to replace old shoes is, most experts agree that between 300 and 500 miles is optimal. In fact, most shoes should be replaced even before they begin to show signs of moderate wear. Once shoes show wear, especially in the cushioning layer called the midsole, they also begin to lose their shock absorption. Failure to replace worn shoes is a common cause of injuries like shin splints, heel spurs, and plantar fasciitis.