Disclosed herein are unicompartmental femoral and tibial arthroplasty jigs for respectively assisting in the performance of unicompartmental femoral and tibial arthroplasty procedures on femoral and tibial arthroplasty target regions. The jigs each include a mating surface. The mating surface of the femoral jig is configured to matingly receive and contact a generally planar area of an anterior side of a femoral shaft generally proximal of the patellar facet border and generally distal an articularis genu. The mating surface of the tibial jig is configured to matingly receive and contact a generally planar area of an anterior side of a tibial shaft distal of the tibial plateau edge and generally proximal of the tibial tuberosity.