Abstract: A retrofitable attachment for easily and quickly converting most conventional wheelchairs into self-propelled, steerable wheelchairs. The invention includes a drive arrangement easily attachable to one of the rear wheels of the wheelchair, an elongated arm unit easily attachable adjacent one of the front casters of the wheelchair, and a connecting member extending between the arm and rear drive arrangement. The elongated arm unit has an outer drive arm portion and an inner steering arm portion, both of which are mounted for pivotal movement together about a first axis to activate the drive arrangement. Additionally, the occupant of the wheelchair can twist or rotate the inner steering arm position about a second axis to steer the front caster of the wheelchair. The steering arrangement further includes a unique gearing system that eliminates dead spots in the steering and allows for easy and uniform manipulation of the steering arm and front caster.

Abstract: An adjustable joint for a knee orthosis or brace. The joint preferably has a polycentric pivot with first and second members having mating, gear teeth and outwardly extending, elongated bars. As one member rotates about its axis, it causes the other member to rotate in an opposite direction about its axis with the bars travelling along respective first and second paths. In the disclosed embodiments, stop members are selectively positioned along the travel paths of the bars with a portion of one in the path of the upper bar which is attached to the thigh engaging component of the brace and a portion of the other in the path of the lower bar attached to the calf engaging component of the brace. The portions of each stop member are preferably eccentrically mounted for rotation about axes spaced from and parallel to the axes of the first and second members of the polycentric pivot.