Jan 29, 2015
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ACL Injuries: Shape of Knee Bone to Blame?

A recent study has uncovered new reasoning for why female athletes may be more prone to non-contact ACL injuries than male athletes. Published in the February issue of the Journal of Bone and Joint Surgery, the research found that a rounded tibial plateau, which is more common in women than men, may predispose an athlete to an ACL tear.

Researchers examined MRI scans of 173 selected athletes who shared similar risks for ACL injuries based on their activities. The length and shape of the participants’ knee bones were measured, and researchers then compared the results of the 112 athletes who had suffered non-contact ACL injuries to the 61 control subjects who had not suffered ACL injuries.

After analyzing the data, the researchers found that most of the women in the study, whether they had been injured or not, had a shorter, rounder tibial plateau–the upper part of the shin at the knee joint. Only some men in the study showed this trait, and those who did had suffered ACL injuries already.

“A lot of people who have ACL tears have a high degree of laxity (loose ligaments) in their knee joints,” Christopher Wahl, MD, an Orthopaedic Surgeon and Team Physician in the Department of Orthopaedics and Sports Medicine at the University of Washington, and the study’s lead author, told Medical News Today. “When I started looking closely at the MRI images of the ‘lax’ individuals, the tibial plateau seemed very rounded and very short compared to those patients with stable knees. The outside of the knee joint almost doesn’t make sense–it is a round surface resting on a round surface–like a ball on a ball. This would seem to be inherently unstable.”

The findings may provide an explanation for why the re-injury rate of ACL tears is the same among men and women even though, overall, women suffer ACL injuries two to five times more often than men. “We were surprised to find that statistically, most of the women in the study share that geometry, even if they haven’t been injured,” said Wahl. “However, only some men have this geometry, and they were the ones who got ACL tears. Put a different way, instead of asking why all females are more prone to ACL injuries, we might consider why only some men are. The male geometry is more variable than the female’s in this respect.”

To read the abstract of the study “An Association of Lateral Knee Sagittal Anatomic Factors with Non-Contact ACL Injury: Sex or Geometry?” go to: www.jbjs.org and search the study title.

Cracking Coconuts

With worldwide sales exceeding $450 million, coconut water has drawn a lot of attention in the last few years–and is continuing to grow in popularity. Now, a study published in the January issue of the Journal of the International Society of Sports Nutrition offers some research indicating that coconut water may work as well as sport drinks containing carbohydrates and electrolytes when it comes to rehydrating athletes.

In the study, 12 exercise-trained men underwent hour-long periods of dehydrating exercise. The participants lost approximately two percent of their body mass (about 1.7 kilograms) over the course of the hour. After the exercise period, participants drank 125 percent of their lost body mass (about two liters) via one of four different beverages: pure coconut water, coconut water from concentrate, bottled water, and a carbohydrate-electrolyte sport drink. Each participant repeated this protocol four times, in order to be tested with each of the beverages.

Researchers found that both pure coconut water and coconut water from concentrate were equally effective as the sport drink in rehydrating the participants. All four drinks were also found to have similar impacts on performance during a treadmill time-to-exhaustion test.

However, there were more reports of mild stomach upset and bloating resulting from both coconut water options compared to the sport drink or water. Researchers believe these reactions resulted from consuming a large volume of liquid in a short amount of time, and recommend determining individual tolerance to coconut water before use.

The study was funded by the Vita Coco Company, which manufactures the pure coconut water used in the study, although the research was conducted by independent scientists from Miami Research Associates and the University of Memphis. “Additional study inclusive of a more demanding dehydration protocol, as well as a time trial test as the measure of exercise performance, may more specifically determine the efficacy of these beverages on enhancing hydration and performance following dehydration exercise,” the study concluded.

The study “Comparison of coconut water and a carbohydrate electrolyte sport drink on measures of hydration and physical performance in exercise-trained men” can be found at: www.jissn.com/content/9/1/1.

New Thinking on Causes of Concussions The results of a two-year study of high school football players are calling into question traditional thinking about how an athlete obtains a concussion. Instead of being caused by one impact, some concussions may be the result of a series of hits to the head.

Published online in the Journal of Biomechanics in January, the research was performed by the Purdue Neurotrauma Group (PNG) at Purdue University, which studied football players at Jefferson High School in Lafayette, Ind. The group evaluated players with a neurocognitive screening test that was administered before, during, and after each season, in addition to using functional magnetic resonance imaging (fMRI) and helmet sensor impact data.

One critical finding was that brain changes were happening without any outward symptoms of a concussion. The fMRI scans revealed that players who suffered the most hits had increased changes in brain activity, indicating that their mental functions were being adapted due to the impacts. Further, an accumulation of these smaller hits were making the players more susceptible to a concussion.

“The most important implication of the new findings is the suggestion that a concussion is not just the result of a single blow, but it’s really the totality of blows that took place over the season,” Eric Nauman, PhD, Associate Professor of Mechanical Engineering at Purdue and one of the study’s authors, told Science Daily. “The one hit that bought on the concussion is arguably the straw that broke the camel’s back.”

With these findings, researchers may be able to determine the number of blows it takes before brain impairment begins–which may prompt the development of safety guidelines for how many hits players can safely take in a given amount of time. “This is still circumstantial evidence, but it suggests that whether you are concussed or not, your brain is changing as a result of all these hits,” Nauman said.

In response to the study’s findings, the Sports Legacy Institute has proposed a “hit count,” which would limit hits to the head for young athletes in a given amount of time. The idea is based on pitch counts that are used in an effort to reduce overuse injuries in baseball pitchers.

The PNG will continue its research in this area and hopes to add female soccer players to the study. Case studies from players who take the highest number of hits will also be tracked with MRI scans to see if there are permanent structural changes in the brain. Results from this study could help in developing more accurate methods of detecting concussions and cognitive impairment, as well as to characterize model cognitive deficits from head impact more accurately.

To read abstract of the study “Biomechanical correlates of symptomatic and asymptomatic neurophysiological impairment in high school football” go to: www.jbiomech.com and search the study title.

Measuring Muscle Soreness

As one of the most common recurring sports injuries, delayed onset muscle soreness (DOMS) can be a huge problem for athletes of all ages. The condition can cause severe pain 24 to 72 hours following exercise. However, it is not easily measured or quantified because traditional research methods rely upon invasive techniques or subjective data. New research from Loma Linda and Asuza Pacific universities may change this.

Rather than using the visual analogue scale (VAS), which subjectively measures pain by having patients rank their soreness on a scale, researchers measured slight changes in the temperature of skin covering exercised muscles. The measurements were taken non-invasively with thermal infrared imaging.

“The main advantage of this technique is that unlike visual scales, which are kind of a subjective measure of whether someone is sore or not, this technique gives you quantifiable, absolute data,” Jerrold Petrofsky, PhD, Professor of Physical Therapy at Loma Linda and study researcher, told Science Daily.

In the study, which was published in the January issue of the Journal of Visualized Experiments, Petrofsky and fellow researchers wanted to explore the possibility of using thermal infrared imaging in relation to DOMS. Despite being used to detect infections and diseases for over 50 years, this was one of the first times thermal infrared imaging had been used to detect muscle soreness.

Researchers believe that utilizing this measuring technique will allow for a quicker and more accurate diagnosis of DOMS. It is also preferred because it is a less risky and less invasive method, unlike a needle biopsy.

To view the abstract of the study “The Use of Thermal Infra-Red Imaging to Detect Delayed Onset Muscle Soreness” go to: www.jove.com and search the study title.

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