Despite the significant public health impact of intervertebral disc (IVD) degeneration and low back pain, it remains challenging to investigate the multifactorial molecular mechanisms that drive the degenerative cascade. Organ culture model systems offer the advantage of allowing cells to live and interact with their native extracellular matrix, while simultaneously reducing the amount of biological variation and complexity present at the organismal level. Murine organ cultures in particular also allow the use of widely available genetically modified animals with molecular level reporters that would reveal insights on the degenerative cascade. Here, we utilize an organ culture system of murine lumbar functional spinal units where we are able to maintain the cellular, metabolic, and structural, and mechanical stability of the whole organ over a 21-day period. Furthermore, we describe a novel approach in organ culture by using tissues from animals with an NF-κB-luc reporter in combination with a mechanical injury model, and are able to show that proinflammatory factors and cytokines such as NF-κB and IL-6 produced by IVD cells can be monitored longitudinally during culture in a stab injury model. Taken together, we utilize a murine organ culture system that maintains the cellular and tissue level behavior of the intervertebral disc and apply it to transgenic animals that allow the monitoring of the inflammatory profile of IVDs. This approach could provide important insights on the molecular and metabolic mediators that regulate the homeostasis of the IVD.

Intervertebral disc (IVD) degeneration is highly correlated with lower back pain, and thus understanding the mechanisms of IVD degeneration is critical for the treatment of this disease. Utilizing mouse models to probe the mechanisms of degeneration is especially attractive due to the ease of manipulating mouse models and the availability of transgenics. Yet characterizing the mechanical behavior of mice IVDs remain challenging due to their minute size (approximately 540 μm in height and 1080 μm2 in cross sectional area). We have thus developed a simple method to dynamically characterize the mechanical properties of intact mouse IVDs. The IVDs were dissected with the endplates intact, and dynamically compressed in the axial direction at 1% and 5% peak strains at 1 Hz. Utilizing this novel approach, we examined the effects of in vitro ribosylation and trypsin digestion for 24 or 72 hours on the viscoelastic behavior of the whole murine IVD. Trypsin treatment resulted in a decrease of proteoglycans and loss of disc height, while ribosylation had no effect on structure or proteoglycan composition. The 72 hour ribosylation group exhibited a stiffening of the disc, and both treatments significantly reduced viscous behavior of the IVDs, with the effects being more pronounced at 5% strain. Here we demonstrate a novel high-throughput method to mechanically characterize murine IVDs and detect strain-dependent differences in the elastic and the viscous behavior of the treated IVDs due to ribose and trypsin treatments.

Intervertebral disc (IVD) degeneration is a significant contributor to low back pain. The IVD is a fibrocartilaginous joint that serves to transmit and dampen loads in the spine. The IVD consists of a proteoglycan-rich nucleus pulposus (NP) and a collagen-rich annulus fibrosis (AF) sandwiched by cartilaginous end-plates. Together with the adjacent vertebrae, the vertebrae-IVD structure forms a functional spine unit (FSU). These microstructures contain unique cell types as well as unique extracellular matrices. Whole organ culture of the FSU preserves the native extracellular matrix, cell differentiation phenotypes, and cellular-matrix interactions. Thus, organ culture techniques are particularly useful for investigating the complex biological mechanisms of the IVD. Here, we describe a high-throughput approach for culturing whole lumbar mouse FSUs that provides an ideal platform for studying disease mechanisms and therapies for the IVD. Furthermore, we describe several applications that utilize this organ culture method to conduct further studies including contrast-enhanced microCT imaging and three-dimensional high-resolution finite element modeling of the IVD.

Objectives: To evaluate the need for reoperation of geriatric intertrochanteric hip fractures treated with 10-mm cephalomedullary nails versus those treated with nails larger than 10 mm. Design:Retrospective review at a single institution.Setting: Level I trauma center.Patients/Participants: All patients age 60 and over treated with cephalomedullary fixation for an intertrochanteric femur fracture at a single institution.Intervention: Cephalomedullary fixation with variable nail diameters.Main Outcome Measurements: Reoperation rates of geriatric intertrochanteric fractures treated with a size 10-mm diameter cephalomedullary nail compared with patients treated with nails larger than 10 mm.Results: There were no significant differences in reoperation rates when the 10-mm cohort was compared with an aggregate cohort of all nails larger than 10 mm (P = 0.99). This result was true for both allcause reoperation and noninfectious reoperation. There was no difference between cohorts in regards to age, gender, or fracture pattern.Conclusions: A 10-mm cephalomedullary nail can be used in lieu of a larger diameter fixation in patients age 60 and older with intertrochanteric femur fractures while still maintaining a comparable rate of reoperation.

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