The most common cause of Volkmann's ischaemic contracture in a child is -

VOLKMANN&;S ischaemia is an ischaemic injury to the muscles and nerves of the flexor compament of the forearm. It is caused due to occlusion of the brachial aery by a supracondylar fracture. Most commonly affected muscles are the flexor pollicis longus and medial half of flexor digitorum profundus. Muscle ischaemia leads to compament syndrome. REF:- Maheshwari 9th ed - pg no 101.