This multi-phase project was the first to explore the biomechanical response of the temporomandibular joint (TMJ) from a straight punch in boxing. During the first phase, a technique was developed that combined the head impact response from a biofidelic anthropometric test device (ATD) with the calculated punch force from an Olympic class boxer throwing straight punches. The results derived from the ATD were used to determine the risk of head injury in terms of HIC, linear and angular acceleration from a straight punch to the chin. The study suggests that the risk of severe head injury, predicted by HIC, was less than two percent from a straight punch to the chin. The average reported HIC in the study was also well below the proposed NFL concussion threshold of 250. In the study, high angular accelerations were calculated suggesting that a potential injury mechanism in boxing may be angular acceleration of the head.

In the second phase, the forces applied by the boxers to the ATD headform mandible region were used as design parameters for the development of a method to characterizing the overall motion and strains within the TMJ region of a cadaver model. To illustrate the response of the mandible to chin point impacts two impact levels were duplicated. In the first test condition, the threshold force level delivered by an Olympic boxer's straight punch to the jaw region was duplicated in both duration and magnitude. The second condition simulated the average force from a straight punch to the chin for all boxers evaluated in the study. Strain gage rosettes attached to the temporal, maxilla, and mandibular bones surrounding the TMJ suggest an inverse relationship between the strains measured on the temporal bone and the strain measured on the body of the mandible. The results indicate that as the buccal surface on the body of the mandible went into tension, the resulting strains within the base of the skull decreased. The findings suggest the lateral bowing of the mandibular arch under the impacting force may be a mechanism that protects the soft tissue in the region surrounding the TMJ including the intracranial structures located on the base of the skull. The strain data was then correlated to the mandibular motion with high-speed bi-planar x-ray illustrating and the condyle impact locations on the base of the skull.

In the final phase of the study, three different types of mouthguards were analyzed using the cadaver model to determine how their use reduces the strains in the TMJ. The results indicate the strains in the mandible from a chin point impact were reduced with use of a mouthguard but that reduction did not translate to a decrease in strains measured within the base of the skull. The minimal change in strain measured at the base of the skull may have been due to the mouthguard engaging the maxilla;​ creating a second path for applied load to enter this region. Due to the small sample size and biomechanical variability within specimens’, additional research is required to confirm this observation.

Certain areas were not addressed in this study. The accumulative effect of multiple punches landed to the head was not considered. The acceleration levels reported in the boxer evaluations may be sufficient to cause some level of head injury if multiple punches were landed.

This study adds to the understanding of the severity of a chin point impact and the associated biomechanical response of the mandible under a variety of conditions. Future studies in this area should explore minimizing the rotation of the mandible during the impact.