A modular femoral prosthesis system comprising: a stem component configured to be received in a proximal end of a patient's surgically prepared femur, the stem comprising a neck, an elongated body extending distally from the neck, and a trunnion configured to receive a femoral head component extending medially and proximally from the neck, and a plurality of collar components configured to be selectively coupled to the stem component in a fixed position adjacent to the neck of the stem component, each of the plurality of collar components including a base having an inferior surface configured to contact a surgically prepared proximal surface of the patient's femur, the plurality of collar components including: a first collar component including the base, the base of the first collar component having (i) a platform and (ii) a pair of arms (74, 76) extending away from a lateral end of the platform, and a second collar component including (i) the base having a superior surface and (ii) a flange extending away from a lateral end of the base, the flange being configured to secure the second collar component in a fixed position relative to a trochanter of the patient, and characterised in that the flange includes a medial surface that extends away from the superior surface of the base and cooperates with the superior surface of the base to define a non-orthogonal angle relative to the superior surface of the base. a stem component configured to be received in a proximal end of a patient's surgically prepared femur, the stem comprising a neck, an elongated body extending distally from the neck, and a trunnion configured to receive a femoral head component extending medially and proximally from the neck, and a plurality of collar components configured to be selectively coupled to the stem component in a fixed position adjacent to the neck of the stem component, each of the plurality of collar components including a base having an inferior surface configured to contact a surgically prepared proximal surface of the patient's femur, the plurality of collar components including: a first collar component including the base, the base of the first collar component having (i) a platform and (ii) a pair of arms (74, 76) extending away from a lateral end of the platform, and a second collar component including (i) the base having a superior surface and (ii) a flange extending away from a lateral end of the base, the flange being configured to secure the second collar component in a fixed position relative to a trochanter of the patient, and characterised in that the flange includes a medial surface that extends away from the superior surface of the base and cooperates with the superior surface of the base to define a non-orthogonal angle relative to the superior surface of the base. a first collar component including the base, the base of the first collar component having (i) a platform and (ii) a pair of arms (74, 76) extending away from a lateral end of the platform, and a second collar component including (i) the base having a superior surface and (ii) a flange extending away from a lateral end of the base, the flange being configured to secure the second collar component in a fixed position relative to a trochanter of the patient, and characterised in that the flange includes a medial surface that extends away from the superior surface of the base and cooperates with the superior surface of the base to define a non-orthogonal angle relative to the superior surface of the base.