Patent ID: 8690881

Claim:
An instrument system for setting the internal-external rotation of a prosthetic femoral component with respect to a proximal tibia comprising: a bone resection instrument having a planar surface for engaging a planar surface of a resected distal femur and a cutting guide for guiding a tool for resecting a posterior surface of the distal femur and forming a cylindrical surface on the posterior condyle intersecting said planar surface, the cylindrical surface defined by an axis extending in a direction generally perpendicular to said planar surface; and a trial component having a planar surface for engaging the planar surface of the resected distal femur having posterior condyles and having a cylindrical anteriorly facing surface engagable with the resected cylindrical surface on the posterior condyles, wherein said planar surface of the bone resection instrument has a central pivot means for allowing rotation of the cutting guide with respect to the distal femur about said axis.