A customised patient-specific 4-in-1 femoral finishing cutting jig comprising a cutting block (2) which is configured to be placed, in use, in contact with the distal resection surface (sd) of a femur (f) the jig (1) being characterised in that it comprises a reference means (R 9 10) which is connected to said block (2) wherein the reference means (R 9 10) is configured to position, in use, said block (2) relative to the distal resection surface (sd) in a predetermined and patient-specific manner wherein the reference means (R 9 10) comprises a first contact element (9 10) having a first surface (11 12) which is configured to face, in use, a first femoral condyle (cfl cfm) and being customised and patient-specific said first surface (11 12) is configured to be placed against a respective portion of a first femoral condyle (cfl cfm) having a corresponding profile.