Disclosed herein is an arthroplasty jig for use in an arthroplasty procedure on a bone of a patient that forms a ball and socket joint. The arthroplasty jig may include a customized mating region and a resection guide. The customized mating region and the resection guide are referenced to each other such that, when the customized mating region matingly engages a surface area of a proximal femur, the resection guide will be aligned to guide a resectioning of the proximal femur along a preoperatively planned resection plane.