Kreighbaum and Barthels (1996) classify pulleys and levers as 'gravity dependant' resistance machines alluding they merely redirect the user's applied force and do not alter the amount of resistance torque within the ROM. Fleck and Kraemer (2004) classify pulleys and levers as 'variable resistance' machines suggesting attempting to match the user's strength curve is only one purpose of variable resistance equipment. It appears equipment manufactures, most notably, Hammer Strength Equipment, position the lever to compliment the user's strength curve. See variable resistance below.
Shoulder arthroplasty is a complex procedure, which requires a great amount of cutting of deep tissues and bone. The surgeon takes great care to eliminate pain with appropriate analgesia both immediately after surgery and during the rehabilitation process. A long acting local anesthetic infused around the nerves of the joint is often used with general anesthesia during surgery. These regional blocks will provide several hours of pain relief even after a patient has emerged from general anesthesia. A patient-controlled intravenous infusion pump (PCA) is used in the early post-operative period for pain control. By the second or third day after surgery, oral pain relief medication is adequate through the early rehabilitation period (4-6 weeks).
Glenohumeral osteoarthritis must be distinguished from rheumatoid arthritis (RA) affecting the glenohumeral joint. Shoulder involvement is common in RA, although typically fairly late in the course of disease. In one study, 55 percent of 74 patients with RA had developed radiographic evidence of erosive glenohumeral joint disease at 15 years [ 4 ]. The symptoms of glenohumeral osteoarthritis and RA affecting the glenohumeral joint are identical; single joint involvement in an older patient suggests the former, while multiple joint involvement tends to occur in the latter. (See "Clinical manifestations of rheumatoid arthritis" .)