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Condition/Term	Definition
Hip replacement surgery	Hip replacement is a medical procedure in which the hip joint is replaced by a synthetic implant. It is the most successful, cheapest and safest form of joint replacement surgery
Knee replacement surgery	Knee replacement, or arthroplasty of the knee, is a commonly performed operation done to relieve the pain and disability from rheumatoid arthritis or more often osteoarthritis of the knee.
Osteoarthritis	Osteoarthritis (OA, also known as degenerative arthritis or degenerative joint disease, and sometimes referred to as "arthrosis" or "osteoarthrosis" or in more colloquial terms "wear and tear"), is a condition in which low-grade inflammation results in pain in the joints, caused by wearing of the cartilage that covers and acts as a cushion inside joints. As the bone surfaces become less well protected by cartilage, the patient experiences pain upon weight bearing, including walking and standing. Due to decreased movement because of the pain, regional muscles may atrophy, and ligaments may become more lax. OA is the most common form of arthritis. The word is derived from the Greek word "osteo", meaning "of the bone", "arthro", meaning "joint", and "itis", meaning inflammation, although many sufferers have little or no inflammation.
Osteoporosis	Osteoporosis is a disease of bone in which the bone mineral density (BMD) is reduced, bone microarchitecture is disrupted, and the amount and variety of non-collagenous proteins in bone is altered. Osteoporotic bones are more susceptible to fracture. Osteoporosis is defined by the World Health Organization (WHO) as either a bone mineral density 2.5 standard deviations below peak bone mass (20-year-old sex-matched healthy person average) as measured by DXA, or any fragility fracture. While treatment modalities are becoming available (such as the bisphosphonates), prevention is still considered the most important way to reduce fracture. Due to its hormonal component, more women, particularly after menopause, suffer from osteoporosis than men. In addition it may be caused by various hormonal conditions, smoking and medications (specifically glucocorticoids).
Rheumatoid arthritis	Rheumatoid arthritis (RA) is traditionally considered a chronic, inflammatory autoimmune disorder that causes the immune system to attack the joints. It is a disabling and painful inflammatory condition, which can lead to substantial loss of mobility due to pain and joint destruction. RA is a systemic disease, often affecting extra-articular tissues throughout the body including the skin, blood vessels, heart, lungs, and muscles. The name is derived from the Greek rheumatos meaning "flowing", the suffix -oid meaning "in the shape of", arthr meaning "joint" and the suffix -itis, a "condition involving inflammation".
TENS machine	A Transcutaneous Electrical Nerve Stimulator, more commonly referred to as a TENS unit and pronounced tens, is an electronic device that produces electrical signals used to stimulate nerves through unbroken skin. The name was coined by Dr. Charles Burton. The unit is usually connected to the skin using two or more electrodes. A typical battery-operated TENS unit consists of a pulse generator, small transformer, frequency and intensity controls, and a number of electrodes.