Hip replacement, also known as hip arthroplasty, is one of the most common surgical procedures in the United States, with approximately 332,000 total hip replacements performed in 2010 alone as a way to correct a variety of types of hip pain. Patients experiencing hip pain have numerous non-surgical options, but depending on the type of damage and efficacy of treatments like physical therapy and medication, a hip resurfacing or replacement may be necessary. Your doctor or an orthopedic specialist can help you determine the best course of action to manage hip pain.
The hip is a ball-and-socket joint that connects the leg to the rest of the body. The ball-shaped top of the femur, known as the femoral head, fits into the “socket” of the pelvis, known as the acetabulum. The ball and socket that make up the joint are separated by a spongy cartilage and synovial fluid that serve to lubricate the joint. All of these components, properly functioning, are important to normal day-to-day activities. However, because of the strain placed on the hip joint over a lifetime, hip pain is a common occurrence, particularly in the elderly.
|Common Causes of Hip Pain|
|Osteoarthritis||Usually occurs in people over 50, as the cartilage in the hip wears away from a lifetime of use. Without a cushion of cartilage, friction between the bones of the hip causes pain.|
|Rheumatoid Arthritis||An autoimmune disease wherein the synovial membrane (a thin membrane that secretes the “lubrication” between the femoral head and acetabulum) is inflamed, which can cause cartilage damage.|
|Post-Traumatic Arthritis||Caused by cartilage damage due to a serious hip injury, such as a fracture.|
|Avascular Necrosis||Certain hip injuries and diseases can limit the flow of blood to the femoral head, causing the surface of the bone to collapse.|
|Childhood Hip Disease||Even when treated successfully, hip problems in children can cause the hips to heal irregularly or develop improperly, leading to pain later in life.|
Hip bone deterioration, arthritis, inflammation that may be caused by previous injury, damage, and overall wear and tear of the joint can all lead to pain and rough surfaces within the joint. Damage usually occurs at the junction of the femoral head (ball) and acetabulum (socket).
Hip pain can cause a difficulty or in some cases an inability to walk. Surgery to replace the damaged joint may be required, but alternative approaches exist that can be taken to help with the pain and joint stiffness. Discuss with your doctor different options that may help to reduce the pain and decide on what options and course of therapy is right for you.
Osteoporosis refers to a progressive loss of bone density, resulting in weaker bones that are more apt to break or fracture at even mild trauma. Aging, heredity, diet and lifestyle are all factors in osteoporosis, as are certain medications and medical conditions. Osteoporosis is a often a factor in hip fractures, which frequently lead to hip replacement surgery.
Osteoporosis can make hip replacement surgery more difficult in cases when the bone has deteriorated so much that it can’t support the weight of the implant. It can also contribute to implant failure. Hip replacements that utilize a cementless femoral stem have a higher incidence of periprosthetic fracture in patients with osteoporosis, and total hip arthroplasty after a hip fracture may make dislocation more common.
Patients who opt for hip replacement can opt for one of two basic surgical options. Traditional hip replacement involves a single large incision, while minimally invasive hip replacement utilizes one or two smaller incisions. Minimally invasive replacement tends to require a longer procedure but may potentially have a shorter recovery time. Candidates tend to be younger, healthier and thinner. Very little is known about the long-term outcomes of minimally invasive hip replacement, however.
Hip surgery may involve total or partial hip replacement, or it may involve hip resurfacing. Your orthopedic surgeon can determine which hip implant will offer the most benefit and least risk for you.
During total hip replacement surgery, the surgeon must create a new joint. The damaged portions of the hip joint are removed and the femoral head is replaced with either the metal or ceramic prosthetic ball of the implant device, while the socket (acetabulum) is replaced with a prosthetic cup. The cup can consist of one or two components made of metal, ceramic or plastic. A stem is also placed in the femur to support the femoral head. This procedure can be performed with cement to secure the implant in place; cementless, where the design of the implant allows new bone to grow into the implant; or a hybrid of both procedures. All three bonding methods depend on the surfaces the surgeon has to work with and the particular patient’s needs, and all three have their advantages and disadvantages.
If only one component of the hip is damaged or worn, partial hip replacement may also be an option depending on the extent of injury to the joint.
During hip resurfacing surgery, the femoral head is trimmed and capped with a metal covering. Any damaged bone and cartilage within the socket are removed and replaced with a metal shell. In hip resurfacing surgery, both components are made of metal. This surgery can be used to delay total hip replacement and usually depends on the age of the patient.
While there are many different hip implants on the market, they are all broadly the same in that they mimic the ball-and-socket structure of the hip and are designed to allow the most natural joint motion possible. The implants consist of a metal femoral stem with a metal or ceramic ball in place of the damaged femoral head, and a metal, ceramic or plastic socket in place of the acetabulum. A liner, also made of metal, ceramic or plastic, is placed in the socket, enabling smooth movement.
Metal-on-metal implants have been plagued by reports of problems since their introduction, leading to several voluntary manufacturer recalls and thousands of lawsuits.
As with any surgery, hip replacement carries its own set of risks and potential side effects. Like all surgery, anaesthesia used during the procedure can cause adverse reactions like heart attack, stroke, pneumonia and blood clots. Infection can lead to pain, scarring, and even the need for a new hip implant.
Some patients come out of hip replacement surgery feeling as though one leg is longer than the other. This is a sometimes unavoidable consequence of the surgery, and may be a deliberate choice by your surgeon to promote optimal functionality of the implant. Some patients elect to wear an elevator shoe to counteract the imbalance.
Additionally, problems with the implant itself can cause long-term side effects; many of these can be fixed without additional surgical procedures, but revision surgery may be necessary. No implant is indestructible, and everyday wear and tear may eventually cause a need for a new device. Patients with active lifestyles will need to manage their physical activity to avoid damaging their artificial hips.
The implant may become dislocated or loosen from the bone to which it’s fixed. Potential symptoms of a failing or malfunctioning hip implant include pain, swelling, difficulty walking, and noises from the joint, such as popping, grinding, clicking or squeaking.
Though marketed as more durable than other types of implants, metal-on-metal hip implants have been plagued by problems. The implants can release toxic metal debris due to friction from the components rubbing together. The metal, usually chromium or cobalt, can cause metallosis, a condition that leads to a variety of painful and debilitating side effects. Because of the FDA’s 510(k) approval process for certain medical devices, metal-on-metal implants did not undergo extensive clinical testing before being used in patients.
Metal-on-metal hip implants have a higher failure rate than other varieties and require corrective surgery more frequently.
If you experience problems with your hip implant, additional surgeries, known as revision surgeries, may be necessary to correct the problem or even replace the device. Metal-on-metal hip implants are more likely to require revision surgeries than other types of implant.
When conventional approaches like physical therapy do not work or they are not enough to reduce the pain in the joint, hip resurfacing or hip replacement is an option.
While the FDA has not ordered a general recall of metal-on-metal hip implants, several manufacturers have recalled individual models. The most extensive of these was executed by DePuy Orthopedics, a division of Johnson & Johnson, which recalled its ASR (Articular Surface Replacement) implant due to a high failure rate. Other manufacturers, such as Stryker, have also recalled select devices.
In 2013, Great Britain’s National Health Service announced it would ban NHS hospitals from using hip implants with a failure rate above 5%. Every model of metal-on-metal hip implant currently on the market will be affected by the ban.
Thousands of lawsuits have been filed against manufacturers of metal-on-metal hip implants due to the high failure rates of the devices, their side effects, alleged improper testing, and claims that the companies misled consumers. Over 12,000 suits have been filed against DePuy alone. Many more remain in litigation.
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