A wheelchair leg-rest adapter is configured to attach to a wheelchair using mounting features functionally compatible with those of a leg rest suitable for the wheelchair, and having mounting features functionally compatible with those of a wheelchair suitable for the leg rest. The leg-rest mounting features are pivotally connected to the structure comprising the wheelchair mounting features, so that a leg rest attached to the former can rotate relative to a wheelchair attached to the latter. The adapter further comprises an adjustment mechanism to move an effective pivot point between the leg-rest and wheelchair mounting features at least in a vertical direction, to bring the pivot point near the knee of a user of the wheelchair.