Adjustable and modular systems, devices and methods for accurately cutting or resecting bones during surgery, particularly in preparation for installing joint implants during arthroplasties, including, but not limited to, preparation of femur or tibia during knee arthroplasties, such as total knee arthroplasty. The embodiments of the present invention provide solutions for adjusting a position of the cutting guides, or structures for guiding or directing the implements for resecting a patient's bone tissue, such as saws. The systems and devices comprise an adjustor for adjusting the cutting guide's position at the patient's bone in at least one degree of rotational freedom and in at least one degree of translational freedom.