A method and system for designing a patient-specific orthopaedic surgical instrument includes coupling a knee sleeve to a leg of the patient. The knee sleeve includes sensors configured to generate sensor data indicate of the position of the respective sensor. The method also include determining angulation data indicative of the angulation of the knee based on the sensor data. The angulation data may be indicative of, for example, the ligament laxity of the knee. The method may also include generating a medical image(s) of the knee. The design of the patient-specific orthopaedic surgical instrument is determined based on the angulation data and the medical image(s).