The hip is a major weight-bearing joint in the human body, and therefore very vulnerable to the degenerative changes of aging that can lead to osteoarthritis. In addition, being overweight or prior injuries can also play a role in development of this disease. When there is not enough cushioning, the bones of the hip joint rub against each other and cause pain and/or limited range of motion. Osteoarthritis is one of the 10 most disabling diseases in developed countries. The World Health Organization (WHO) estimates that 10% of men and 18% of women age 60 and older have symptomatic osteoarthritis worldwide, including moderate and severe cases. Hip replacement surgery is considered the most effective intervention for severe osteoarthritis of the hip joint, reducing pain and disability and restoring near normal function to many patients. It may also be used in patients that have suffered an acute hip injury.
First performed in 1960, hip replacement surgery, also known as total hip arthroplasty, has witnessed huge strides in techniques and device technology since its implementation. The National Center for Health Statistics at the Centers for Disease Control and Prevention published a report in February 2015 that showed that the number of hip replacement procedures done annually in the U.S. more than doubled in a 10-year period, from 138,700 in 2000 to 310,800 in 2010. Among those age 75 and older, the number of hip replacements increased by 92% to 80,000 procedures, and in those age 45 to 54, it increased by 205% to 51,900 procedures. Concurrently, Europe has also experienced a growing number of hip replacement surgeries. In 2012, Germany, Austria, Sweden, Finland and Belgium had the highest rates of hip replacement among EU countries. In Denmark, the number of hip replacements per 100,000 population increased by 40% between 2000 and 2012. Many orthopaedic experts believe that the increase is due not only to a growing number of people with debilitating osteoarthritis, but also to surgical advancements that have made the procedure easier. Recovery time has lessened, durability has increased, and the procedure has become more cost effective.
Orthopaedic surgeons generally recommend hip replacement surgery for patients whose pain is chronic and very severe and/or patients with greatly reduced range of motion, despite taking anti-inflammatory drugs and undergoing physical therapy. Diagnostic tools include x-rays and arthrocentesis – a procedure in which a sterile needle is used to remove joint fluid to rule out gout, infection, and other causes of inflammatory arthritis. Hip replacement surgery normally takes several hours, during which damaged cartilage and bone is removed and replaced with a prosthetic hip joint. Hip replacements may be cemented, uncemented, or hybrid (a combination of cemented and uncemented components), depending on the type of fixation used to hold the implant in place.
Cemented total hip replacement is commonly recommended for older patients, those with conditions such as rheumatoid arthritis, and for younger patients with compromised health or poor-bone quality and density. These patients are less likely to put stress on the cement, which potentially can lead to fatigue fractures. Traditional total hip replacement involves making a 10- to 12-inch incision on the side of the hip, splitting and detaching the muscles from the hip, thereby dislocating the hip joint so it can be visualized and readily accessed by the orthopaedic surgeon.
Minimally invasive total hip replacement can be performed using either one or two small incisions, allowing for less tissue disturbance. During single-incision surgery, an incision of 3 to 6 inches is usually made on the outside of the hip. The muscles and tendons are split or detached from the hip, but less so than in traditional hip replacement surgery. The surgeon will routinely repair the muscles and tendons right after the implants are in place. This encourages healing and helps prevent dislocations. Two-incision surgery involves a 2- to 3-inch incision over the groin for placement of the socket, and a 1- to 2-inch incision over the buttock for placement of the femoral stem. It is more difficult to visualize and access the hip joint with this approach, so x-ray guidance is often used.