Limb lengthening by distraction osteogenesis and external fixation is used increasingly in the United States for a variety of orthopaedic conditions. Maintenance of joint motion, critical for successful outcomes, can be difficult to achieve. The rate of growth needed for distraction osteogenesis is faster than that of normal growing bone. Histogenesis of soft tissues must also occur to maintain the motion in joints above and below the limb being lengthened. Physical therapists in patients' home communities need to be knowledgeable about the aggressive management needed to prevent the loss of joint motion. This article introduces physical therapists to a commonly used external fixator, the procedure of distraction osteogenesis, and the role of functional loading. To assist in treatment planning, a physical therapy management plan is presented. Two case examples illustrate how therapists can assess a patient's status relative to the goals in the management plan and determine intervention priorities.