A bone cut positioning system, comprising: a positioning assembly, including: a femoral attachment member configured to be fixed to a distal end of a femur, the femoral attachment member including a first tongue with at least one fixation aperture; a light emitter mounting member configured to receive a light emitter; a channel; a varus-valgus adjustment member configured to adjust a position of the positioning assembly relative to the femur to achieve a desired varus-valgus angle; and a flexion-extension adjustment member configured to adjust a flexion-extension position of the positioning assembly; and a guide member, characterised in that the first tongue is adapted for securement to the anterior cortex of the femur proximal to the distal end of the femur and in that the guide member is configured to extend from a depth selector slide, the depth selector slide configured to be received within the channel of the positioning assembly, the guide member comprising at least one femoral contact surface, the depth selector slide configured to move within the channel to move the guide member proximally-distally relative to the femur to cause the at least one femoral contact surface to engage the distal end of the femur to determine a desired resection level. a positioning assembly, including: a femoral attachment member configured to be fixed to a distal end of a femur, the femoral attachment member including a first tongue with at least one fixation aperture; a light emitter mounting member configured to receive a light emitter; a channel; a varus-valgus adjustment member configured to adjust a position of the positioning assembly relative to the femur to achieve a desired varus-valgus angle; and a flexion-extension adjustment member configured to adjust a flexion-extension position of the positioning assembly; and a guide member, characterised in that the first tongue is adapted for securement to the anterior cortex of the femur proximal to the distal end of the femur and in that the guide member is configured to extend from a depth selector slide, the depth selector slide configured to be received within the channel of the positioning assembly, the guide member comprising at least one femoral contact surface, the depth selector slide configured to move within the channel to move the guide member proximally-distally relative to the femur to cause the at least one femoral contact surface to engage the distal end of the femur to determine a desired resection level. a femoral attachment member configured to be fixed to a distal end of a femur, the femoral attachment member including a first tongue with at least one fixation aperture; a light emitter mounting member configured to receive a light emitter; a channel; a varus-valgus adjustment member configured to adjust a position of the positioning assembly relative to the femur to achieve a desired varus-valgus angle; and a flexion-extension adjustment member configured to adjust a flexion-extension position of the positioning assembly; and a guide member, characterised in that the first tongue is adapted for securement to the anterior cortex of the femur proximal to the distal end of the femur and in that the guide member is configured to extend from a depth selector slide, the depth selector slide configured to be received within the channel of the positioning assembly, the guide member comprising at least one femoral contact surface, the depth selector slide configured to move within the channel to move the guide member proximally-distally relative to the femur to cause the at least one femoral contact surface to engage the distal end of the femur to determine a desired resection level.