Rotational acceleration of the head is a principal cause of concussion and traumatic brain injury. Several rotation-damping systems for helmets have been introduced to better protect the brain from rotational forces. But these systems have not been evaluated in snow sport helmets. This study investigated two snow sport helmets with different rotation-damping systems, termed MIPS and WaveCel, in comparison to a standard snow sport helmet without a rotation-damping system. Impact performance was evaluated by vertical drops of a helmeted Hybrid III head and neck onto an oblique anvil. Six impact conditions were tested, comprising two impact speeds of 4.8 and 6.2 m/s, and three impact locations. Helmet performance was quantified in terms of the linear and rotational kinematics, and the predicted probability of concussion. Both rotation-damping systems significantly reduced rotational acceleration under all six impact conditions compared to the standard helmet, but their effect on linear acceleration was less consistent. The highest probability of concussion for the standard helmet was 89%, while helmets with MIPS and WaveCel systems exhibited a maximal probability of concussion of 67 and 7%, respectively. In conclusion, rotation-damping systems of advanced snow sport helmets can significantly reduce rotational head acceleration and the associated concussion risk.

No abstract

Anterior cruciate ligament (ACL) tears are one the most prevalent activity-related injuries among athletes in the United States. ACL reconstructive surgeries are typically done using a patellar tendon graft or hamstring tendon graft. There is debate as to which type of graft surgery is best, as surgeon preferences between the two differ. Thus, the primary aim of this pilot study was to compare the aforementioned ACL surgical techniques. A secondary aim was to provide physical therapists and patients with real-time feedback about the progress of the recovery over time when performing a common physical therapy exercise regimen.The results of this pilot study demonstrate that the surgical techniques can be evaluated using a dynamic multi-system approach. These systems include 1) a motion capture system, 2) electromyography (EMG) sensors, and 3) a force platform system. The significant parameters included knee flexion, maximum muscle activity from the muscles around the knee, and balance control variables.The results of the study revealed that when considering the knee flexion data, the hamstring graft is more beneficial than the patellar tendon graft in terms of showing progress over the course of the study. With regards to EMG and force platform results, the data proved either inconclusive or favoring the patellar tendon graft technique during the chair squat and sit to stand activities. With this research, we can conclude that real-time feedback may be a useful approach for ACL rehabilitation, and in determining which surgical approach may be most ideal for recovering patients.