Patient specific surgical instruments, and in particular cutting guides, and methods of use and manufacture are described. The surgical instrument can be used in an orthopaedic arthroplasty procedure to be carried out on a joint of a patient and can allowing soft tissue balancing for the joint. The instrument comprises a body having an attachment area configured using data specific to a bone of the joint of the patient so as to attach to the bone in a unique position. The instrument includes at least a first cutting guide and an adjustment mechanism operable to change the position of the cutting guide relative to the bone.