These patterns of response are common to other knee joint sensitization methods as is sustained spiking activity after noxious stimulation has ended which is hypothesized to be due to sustained C-fiber activity. MIA sensitized neural responses are also susceptible to pharmacological modulation. Despite the characterization of knee joint pain processing in the periphery of sensitized rats, very little is known about the state of processing in the spinal dorsal horn. Cellular and molecular changes do occur in the spinal cord such as increases in COX-1/-2, proinflammatory cytokines, pain related neuropeptides, activation of mitogen activated protein kinases and microglial activation, suggesting that pain processing in the spinal cord is important to the behavioral effects in this model. Wide dynamic range neurons receiving direct input from the MIA sensitized knee joint have shown increased spontaneous spiking activity but the majority of spinal cord physiology studies focus on secondary sensitization arising in the ipsilateral paw. Here we report a test of the prediction that two clinically effective compounds, naproxen and oxycodone, are efficacious in reducing the response of spinal dorsal horn neurons to noxious knee joint rotation in the MIA sensitized rat. The objective for these PD325901 experiments was to develop a high quality in vivo electrophysiology assay to confidently test novel compounds for efficacy against pain. The overall objective for these experiments was to develop a high quality in vivo electrophysiology assay to confidently test novel compounds for efficacy against pain. Assay development is an evolving process of experimentation and refinement. The experimental methods and results presented here were developed under the guidance of a novel tool, the Assay Capability Tool, to strive for the highest possible standards of experimental conduct. The ACT was developed to guide both the development of assays and the assessment of their capability to generate reliable data. The tool is particularly useful in standardizing decision making in drug discovery but can also be applied to published experiments. This aids in the estimation of the confidence one can have in the validity of the results and guides follow-up studies. We started by running a small pilot study with oxycodone to assess whether this model was able to detect electrophysiological changes following drug administration. This pilot study indicated that the experimental approach was viable. We then moved on to test novel predictions about the efficacy of oxycodone and naproxen, two clinical standards of care for knee joint pain, which have differing mechanisms of action. Our next experiment was designed to further explore the role of oxycodone versus vehicle-treated controls in modulating sensitized knee joint rotation processing in the spinal cord. This provided the information to design a follow-up study to test the validity of tonic spiking activity as a primary endpoint and to test the role of naproxen. In the oxycodone experiment, our objective was to test predictions about the role of opioid receptors in modulating four knee joint rotation response types.