February 9, 2012

Risks Of Traumatic Neuromechanical Injury Associated With Boxing And Mixed Martial Arts

Preliminary analysis

Boxing and mixed martial arts (MMA) carry risks of head and neck injuries. Padded gloves and headgear are designed to lessen these risks, primarily those resulting from linear acceleration. But what about other types of impact? To date there has been little testing of rotational acceleration or rotational velocity, and no current rotational head injury scoring system. Knowing that rotational acceleration, rotational velocity, and combined linear-rotation impacts are key contributors to head and neck injuries, researchers in Ohio (Cleveland Clinic, Case Western Reserve University, and SEA Ltd.) and West Virginia (United Hospital Center Neurosurgery & Spine Center) set out to simulate head and neck injuries sustained during hook punches and test whether these risks are mitigated by available head and hand padding. The researchers found that padding lowered linear but not rotational impact dosages, and did not eliminate the risk of brain strain injury. These findings can be found in the article "Boxing and mixed martial arts: preliminary traumatic neuromechanical injury risk analyses from laboratory impact dosage data. Laboratory investigation," published online February 7th in the Journal of Neurosurgery.

In the laboratory, Adam Bartsch, Ph.D., and colleagues evaluated linear, rotational, and combined linear-rotational impact dosages sustained by a Hybrid III anthropomorphic test device (ATD)——a crash test dummy representing a man in the 50th percentile. A pendulum was set up to deliver 54 blows to the left side of the ATD "head," replicating a right-handed hook punch at low (27 to 29 joules) and high (54 to 56 joules) impact energy levels. The "head" was tested bare or covered with padded boxing headgear; the pendulum was tested bare or covered by a padded boxing or MMA glove. Five impact conditions were investigated: bare head and boxing glove, bare head and MMA glove, boxing headgear and boxing glove, boxing headgear and unpadded pendulum, and bare head and unpadded pendulum (control). Each impact condition was examined six times at both low and high impact energy levels, except the one involving the boxing headgear and boxing glove, which was only tested at the high impact energy level. Impact dosage data were quantified according to 17 dynamic head and neck injury risk parameters (such as head acceleration, impact duration, angular acceleration, and kinetic energy transfer), which were separated into linear, rotational, and combined linear-rotational groups.

In addition to the ATD, the researchers used a Simulated Injury Monitor (SIMon) finite element brain model, a software program that takes into account various parts of the brain and how they theoretically respond during injury. The SIMon model provides information on brain compression, stretching, and pressure. Data obtained from the ATD experiment–specifically linear acceleration and angular velocity–were entered into the SIMon model. This yielded an assessment of the risks of various brain injuries such as acute subdural hematoma and diffuse axonal injury.

The researchers found that all impact conditions involving padding reduced linear but not rotational impact dosages delivered by the "hook punch." Not surprising, the best overall reduction in impact dosage was found when boxing glove and headgear were both used. However, a heightened theoretical risk of brain strain injury was associated with both boxing and mixed martial arts regardless of what padding was used. This last finding surprised the researchers, because the theoretical risk persevered even under conditions in which padding significantly reduced impact dosage.

One of the coauthors of this study, Vincent Miele, M.D., was an amateur boxer in the past and is currently a ringside physician. His interest in making boxing and mixed martial arts safer by reducing head and spine injuries spurred the interest of the research team.

The authors state that their results are preliminary and indicate how essential it is to develop improved protective padding that will lower both linear and rotational impact dosage during these combat sports. They also point out the need to develop new standards for measuring head and neck injury risk that take into account rotational and combined linear-rotational parameters.


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