Apparatus is disclosed for monitoring, measuring and/or estimating deviation of a body part of a vertebral mammal. The apparatus includes at least one sensor for measuring rotation of the body part relative to a first frame of reference and for providing data indicative of the rotation. The apparatus also includes a memory device adapted for storing the data and a processor adapted for processing the data to evaluate a deviation of the body part that correlates to the data. The processor may be configured to execute an algorithm for evaluating deviation of the body part. A method of monitoring, measuring and/or estimating deviation of a body part of a vertebral mammal is also disclosed.