This procedure uses a small, metal, cap-like implant to cover damaged or missing articular cartilage in the shoulder joint. Articular cartilage covers the joint surfaces of bones, allowing them to glide smoothly against each other. In the shoulder, arthritis or an injury may result in loss or damage of the cartilage on the round humeral head, causing pain and limited motion. Resurfacing this damaged area can help relieve pain and improve motion.