[Photograph 2012.201.B1080.0397]

Photograph used for a story in the Daily Oklahoman newspaper. Caption: "Forrest "Tiny" Reed of Pawnee just kind of slings his boot sideways.

Cervical spine curvature during simulated whiplash

Objective. To develop a new method to describe cervical spine curvature and evaluate the potential for injury in the upper and lower cervical spine during simulated whiplash. Design. A method was developed to integrate the upper and lower cervical spine rotations and describe the spine curvature. Background. In vivo and in vitro whiplash simulations have documented the development of an S-shape curvature with simultaneous upper cervical spine flexion and lower cervical spine extension immediately following rear- impact. Investigators have hypothesized that the injury potential is highest during the S-shape phase. However, little data exist on the spine curvature during whiplash and its relation to spine injury. Methods. A biofidelic model and a bench-top whiplash apparatus were used in an incremental rear-impact protocol (maximum 8 g) to simulate whiplash of increasing severity. To describe the spine curvature, the upper and lower cervical spine rotations were normalized to corresponding physiological limits. Results. Average peak lower cervical spine extension first exceeded the physiological limits (P < 0.05) at a horizontal T1 acceleration of 5 g. Average peak upper cervical spine extension exceeded the physiological limit at 8 g, while peak upper cervical spine flexion never exceeded the physiological limit. In the S- shape phase, lower cervical spine extension reached 84% of peak extension during whiplash. Conclusions. Both the upper and lower cervical spine are at risk for extension injury during rear-impact. Flexion injury is unlikely

Radiofrequency probe treatment for subfailure ligament injury: a biomechanical study of rabbit ACL

Objective. Utilizing a rabbit anterior cruciate ligament model of ligamentous subfailure injury, biomechanical properties of injured ligament treated with radiofrequency energy were evaluated. It was hypothesized that an injured ligament treated with radiofrequency probe would demonstrate restoration of biomechanical properties lost through injury. Background. Radiofrequency probe, thermal treatment has been utilized in the clinical setting to address joint instability caused by ligamentous laxity from injury or repetitive microtrauma. The biomechanical effects of radiofrequency probe thermal treatment on injured ligamentous tissues have not been studied in the laboratory. Design. Three groups of specimens: Control, Sham, and Treatment, 10 each, were tested under identical conditions. Methods. Viscoelastic behavior was analyzed using a relaxation test (6% strain, up to 180 s) performed before injury, after injury, and after injury plus sham or injury plus radiofrequency probe treatment. Results. After injury the normalized forces in the relaxation test decreased by approximately 50%. The post-treatment relaxation test revealed significant ( P<0.01) restoration of the average relaxation force in the Treatment group to that of the Control group (0.79, SD 0.11 vs. 0.80, SD 0.10). Both of these groups were significantly different from the Sham group (0.44, SD 0.11). Additionally, stretch-to-failure test showed partial restoration of the toe region of the load–deformation curve by the radiofrequency treatment. Conclusions. The radiofrequency probe treatment is shown to be an effective mechanism for restoring initial ligament tensile stiffness and viscoelastic characteristics lost by the subfailure injury in vitro. Relevance This study employs a proven ligament subfailure injury model and examines the biomechanical consequences of radiofrequency probe thermal treatment, in vitro. These results support the theoretical basis of arthroscopic, electro-thermal capsule shift procedures for subfailure injuries. However, this study does not provide evidence that these improved biomechanical properties are sustained in vivo

Single and incremental trauma models: a biomechanical assessment of spinal instability

Biomechanical analysis of spinal injury in the laboratory requires the development of trauma models that simulate spinal instability. Current experimental trauma protocols consist of two types: single or incremental impacts. The incremental protocol has several advantages. However, the equivalence of the spinal instabilities produced by the two trauma protocols is currently unproven. The purpose of this study was to investigate whether the single and incremental trauma models produce equivalent soft tissue instabilities in the lumbar spine. Ten freshly frozen porcine lumbar spines were divided into two functional spinal units (FSUs), L2-L3 and L4-L5. FSUs were then randomized to either the single trauma (ST) or incremental trauma (IT) protocol. The IT protocol consisted of four sequentially increasing high-speed axial compression traumas, while the ST protocol was a single impact of the same magnitude as the final trauma of the IT. Before and after the final trauma, each FSU underwent flexibility testing under flexion/extension, lateral bending, and axial torsion pure moments. No significant differences were found in neutral zone or range of motion between IT and ST specimens in any of the three axes of motion, either before or after the trauma. In addition, no differences were found between the normalized motions of the IT and ST groups. The FSUs subjected to incremental trauma do not suffer greater injury than those subjected to a single impact. The data support the equivalency of the subfailure soft tissue injuries of the spine caused by the incremental and single trauma protocols respectively. This finding is important, because only with the incremental trauma protocol is one able to obtain injury threshold, study injury progression in the same specimen, produce a defined injury more accurately, and efficiently utilize scarce human cadaveric specimens