A spica cast is used as treatment to stabilize the hips, legs, or pelvis. It may be needed as treatment for abnormal bone or joint development (such as developmental dysplasia of the hips, or DDH) or for problems resulting from an injury. The cast is made from plaster or fibreglass. It is worn continuously, usually for 2 to 3 months.

Soft padding, such as moleskin, is placed around the edges of the cast in the diaper area. For babies and young children who are not toilet trained, a small diaper is tucked beneath the cast.