An orthopaedic demonstration aid for demonstrating surgical orthopaedic techniques, the aid comprising: - first and second facsimile human bone portions forming a facsimile human knee joint capable of being manipulated relative to one another to mimic the action of a skeletal joint, - an elongate first shaft portion to one end of which the first bone portion is detachably secured to enable replacement of the first bone portion, - an elongate second shaft portion to one end of which the second bone portion is detachably secured to enable replacement of the second bone portion, - adjustable holding means for adjustably holding the first shaft portion in a required position, characterised in that the aid further comprises - a facsimile human foot at the end of the second shaft portion (distal from the second facsimile bone portion, - releasable securing means for holding the facsimile human foot and thus the second shaft portion at the correct anatomical orientation for the purposes of the required surgical orthopaedic procedure, - a hip portion attached to the end of the first shaft portion distal from the first facsimile bone portion, - a ball attached to the hip portion at a compound angle such that the first shaft portion is oriented at the correct anatomical angle in two mutually perpendicular planes relative to the adjustable holding means, - the adjustable holding means including a socket for receiving the ball, the aid ensuring that the first and second bone portions have the correct relative anatomical orientation by ensuring the correct alignment of the anatomical axes of both of the first and second shaft portions relative to a mechanical axis passing through the hip joint and knee joint. - first and second facsimile human bone portions forming a facsimile human knee joint capable of being manipulated relative to one another to mimic the action of a skeletal joint, - an elongate first shaft portion to one end of which the first bone portion is detachably secured to enable replacement of the first bone portion, - an elongate second shaft portion to one end of which the second bone portion is detachably secured to enable replacement of the second bone portion, - adjustable holding means for adjustably holding the first shaft portion in a required position, - a facsimile human foot at the end of the second shaft portion (distal from the second facsimile bone portion, - releasable securing means for holding the facsimile human foot and thus the second shaft portion at the correct anatomical orientation for the purposes of the required surgical orthopaedic procedure, - a hip portion attached to the end of the first shaft portion distal from the first facsimile bone portion, - a ball attached to the hip portion at a compound angle such that the first shaft portion is oriented at the correct anatomical angle in two mutually perpendicular planes relative to the adjustable holding means, - the adjustable holding means including a socket for receiving the ball, the aid ensuring that the first and second bone portions have the correct relative anatomical orientation by ensuring the correct alignment of the anatomical axes of both of the first and second shaft portions relative to a mechanical axis passing through the hip joint and knee joint.