A directional causal effect cannot be extrapolated for specific MPT techniques as multiple techniques were used. The influence of the Hawthorne effect, which is the tendency of individuals to perform better in a research setting as they are being assessed,60 can not be ignored, as each therapist in this case series was aware that individual patient outcomes were being measured, but no subjects were excluded from outcomes reporting. However, despite the limitations of the case series, the outcomes presented are encouraging for the clinical utilization of MPT techniques and exercise in the treatment of hip OA and patients with primary hip pain satisfying the ACR classification for hip OA. Future studies should investigate the physiological mechanism that promotes improved joint function following nonthrust and thrust mobilization/ manipulation for hip OA. Research assessing the appropriateness of including MPT into the ACR guidelines for the treatment of hip OA, given the outcomes of the Hoeksma et al34 trial and this case series, is warranted. Studies should investigate whether thrust mobilization/manipulation generates a different clinical outcome than nonthrust mobilization/manipulation techniques for hip OA, and whether specific joint testing is necessary to guide mobilizations, or if general application of mobilization/manipulation to the hip will provide benefits in pain and disability for patients with hip OA. Future studies should also inquire into the usage of medications following MPT interventions for hip OA and identify the duration of long-term benefit following MPT for hip OA.