Diseases of The Hip

The anatomy section mentioned some of the potential problems that can be associated with specific anatomical features. Some categories of hip problems are broader, and these need specific discussion. The different types of arthritis are broad categories of disease, and a full discussion of all of the types of arthritis that have been described could fill several textbooks alone. In fact, a rheumatologist is a specialized internist who treats these problems primarily with medicine (nonsurgical treatment) and accounts for an entire medical subspecialty. However, we will focus on some of the more common and important types which together account for the vast majority of orthopaedic surgery patients.

Hip Pain

This chapter discusses the most common types of arthritis and other common causes of hip pain, such as trochanteric bursitis or changes after fractures. True hip joint pain usually presents as groin pain, although occasionally some patients will have primarily buttock or knee pain. Movement of the hip joint typically becomes limited and activities such as putting on socks or clipping toenails becomes increasingly difficult. A limp begins to develop. A small percentage of patients with serious hip disease will actually present with knee pain, which may be due to referred pain because of the overlapping nerve supply. Some types of pain felt around the hip joint may originate from the muscles or other soft tissues outside of the joint itself, such as bursitis. It is also possible that pain in the hip may be completely unrelated to the hip, caused by a lumbar radiculopathy or sciatica (a pinched nerve originating from the spine, usually because of a bulging herniated disc), gynecologic sources, or even a hernia.

Osteoarthritis

This is the “wear and tear” form of arthritis that most patients have. It is often explained to patients as being a gradual wear of the joint (“it's not the years, it's the mileage”), although it typically does not become clinically significant until middle age or later. Nearly all adults over forty will demonstrate at least some osteoarthritis in their joints even though it may not cause pain or problems for many years.

The cartilage coating over the joints wears away, eventually exposing the underlying bony surfaces (analogous to scraping away the Teflon in the frying pan). As this occurs, the body reacts by forming large bone spurs (called osteophytes), extra joint fluid (which may cause an effusion, or joint fluid accumulation), hard underlying bone surfaces (subchondral sclerosis), or cysts around the joint. Eventually, the hip joint begins to resemble a cauliflower more than a smooth, round ball. This usually causes pain in the groin, although it may radiate to the knee, buttock, or side of the hip. The joint becomes progressively stiff, so that it becomes difficult to put on shoes and socks, clip toenails, get up out of a chair, etc.

There is convincing evidence that many patients with osteoarthritis are prone to get it based on their genetics. Some studies involving identical twins suggest that occupation and other factors may not play as great a role as previously thought, and the tendency to develop severe osteoarthritis runs in families. A study recently showed that in identical twins, both usually had similar patterns and severity of osteoarthritis later in life, even if one became a heavy laborer and the other worked at a desk job.

Related forms of osteoarthritis include posttraumatic arthritis (arthritis that forms after an old injury,usually a fracture or a dislocation of the hip), late sequelae or consequences of prior diseases (patients who had slipped capital epiphyses or Legg-Calve- Perthes disease as children), and congenital defects such as a shallow hip socket (hip dysplasia).

Rheumatoid Arthritis

Although many patients may describe their joint pain as "rheumatism," rheumatoid arthritis is a special form of arthritis in which the body's own immune system attacks the joints. This leads to large, swollen joints that are painful and frequently reddened and warm. Rather than attacking a few joints, most rheumatoid arthritis patients have pain in many joints.

Blood tests often can detect or confirm the presence of rheumatoid arthritis (although they are not completely accurate), and it is usually diagnosed by the family physician or a rheumatologist when a patient's symptoms are suspicious. Untreated, the inflammation within the joints leads to destruction of the cartilage in the joint, and the inflammation caused by the body's immune system attacking its own tissues can also have consequences such as tendon ruptures and hand deformities. Newer rheumatologic medications to suppress the autoimmune disease have led to a remarkable decrease in the number and severity of rheumatoid patients that require orthopaedic surgical intervention. However, it remains a common source of joint problems and still accounts for many joint replacement surgeries each year.

Related forms of autoimmune arthritis also include Crohn's disease, ulcerative colitis, and psoriatic arthritis. Many patients are surprised to learn that psoriasis can lead to severe joint arthritis and destruction. Psoriasis is itself an autoimmune problem in which the body attacks itself, leading to eruptions in the skin that are typically associated with the disease. Like rheumatoid arthritis, it is often managed with medications that prevent the autoimmune response.

Avascular Necrosis (Osteonecrosis)

A potentially devastating condition which can affect patients of any age is avascular necrosis, or AVN, of the hip joint, which usually begins as the gradual onset of groin pain that worsens over time. In recent years, this has also been termed osteonecrosis. Essentially it is a syndrome in which the bone in the femoral head (the ball at the top of the thigh bone) begins to die. Usually, it is because that area of bone does not receive enough blood supply, due to a number of potential causes.

Avascular necrosis can be the result of trauma, clotting diseases, Sickle Cell disease, steroid use (usually long term use of oral prednisone), chemotherapy or radiation treatment for cancer, environmental factors (deep sea diving or working in a deep mine, where barometric changes chronically can lead to this disorder), metabolic diseases (such as Gaucher's Disease), and most commonly due to chronic, heavy alcohol use.

However, despite all of the numerous factors identified with causing avascular necrosis, nearly half of all patients have no identifiable risk factors. Many surgeons agree there is about a 50% lifetime risk of the opposite hip eventually becoming affected after developing the disease in one hip. It is one of the most common reasons for hip replacement surgery in young patients, either due to intractable severe pain or from arthritis that results after the bone in the femoral head has died and the round portion of the ball collapses. Avascular necrosis can also affect other joints in the body, notably the knee (in the distal end of the femur), rarely the shoulder, and the small bones of the wrist (Kienbock's disease and Preiser's disease) and foot.

Septic Arthritis

Septic arthritis occurs when a joint becomes infected. This can happen most often with infants (because of the way the developing blood supply feeds the joints, making it easier for a systemic infection to seed a joint space), people who use intravenous drugs (such as heroin), and with patients who have immune system impairments (such as HIV or AIDS). Most surgeons will not consider joint replacement surgeries for patients with a history of IV drug abuse because of the potential of infecting an artificial joint if the patient engages in IV drug use.

Often, the source of the infection is obvious, such as a chronic diabetic ulcer or infection along the leg that has not healed, a severe urinary tract infection, recent unrelated surgery, or recent systemic illness. However, sometimes the source cannot be identified, and it is assumed to have occurred through transient bacteremia (temporary presence of bacteria in the bloodstream, as occurs every day shortly after brushing your teeth).

Patients with septic arthritis of the hip from any source are usually quite ill, with high fevers and severe groin pain with any movement of the hip. The infection can very quickly destroy the cartilage if left untreated (or destroy the bone fixation to an implanted artificial joint). An infection with pus inside any joint is a surgical emergency and usually requires immediate surgery to wash out the joint.

Trauma and Fractures

 

A femoral neck fracture of the hip.	A femoral neck fracture that has been treated with percutaneous pinning. The fracture has healed 6 months after the injury.
A 3 part intertrochanteric hip fracture.	A healed intertrochanteric hip fracture treated with an intramedullary hip screw 6 months after the injury.

There are a number of different fractures that can involve the hip and pelvis, and many of these require surgery to fix and stabilize the bone. Hip fractures are common in elderly patients, who often have osteoporosis (or weak bones) and sustain fractures with falls. There are several different types of hip fractures. Femoral neck fractures (also called subcapital fractures) occur when the femur breaks just below the ball of the femur. This can occur as the result of a fall or sometimes can gradually occur over time as the result of a stress fracture. If the fracture does not displace, this can sometimes be treated with percutaneous pinning. Pinning is very quick and is a minimal surgery compared to other repairs, but the patient must be able to follow directions and limit weightbearing until the fracture has healed, which can be a problem for nursing home patients without the strength or the mental presence to stay off of the hip.

Displaced femoral neck fractures in which the ball falls off the neck of the femur are usually treated with partial or total hip replacements, depending on the activity level of the patient before the injury. Hip fractures that involve the portion below the ball and neck area, in the region of the prominent bony part of the thigh called the greater trochanter, are referred to as intertrochanteric fractures. These often occur from landing directly on the side of the hip. These are usually repaired with either a plate along the side of the femur and a screw going into the head of the femur or with a rod through the femur that is placed in a newer, less invasive surgery (known as an intramedullary hip screw). These methods are also used to repair subtrochanteric fractures, which occur closer to the region of the femoral shaft. Hip replacement is possible for these types of hip fractures but is usually not the first choice of treatment, as fractures in this region of the hip involve the area where the stem of the hip prosthesis is anchored. If hip replacement is used to treat these types of fractures, usually a special type of hip replacement known as a calcar replacing prosthesis is used. The most common reason to use a hip replacement for intertrochanteric or subtrochanteric hip fractures is after a previous fixation with a hip screw fails (usually due to screw cut-out through the soft, osteoporotic bone or because the patient did not follow weightbearing instructions/limitations).

Some fractures involve the socket (acetabulum) of the hip rather than the femur. Acetabular fractures vary in severity. Some fractures involving this socket are minor and are treated without surgery, managed with just limited weightbearing until the fracture heals. Some are more severe, particularly fractures that blow out enough of the socket that the ball cannot stay located and falls out of the joint (dislocates). These require that the socket either be repaired with screws and/or plates, or alternatively, the entire hip may be replaced.

Even when the above types of fractures have healed, most patients develop arthritis years later (known as post-traumatic arthritis). It is similar to osteoarthritis. Patients who previously had a hip dislocation from an accident also often develop arthritis in the hip joint years afterwards. It is not uncommon for patients who have successfully healed from hip or acetabular (socket) fractures to eventually require hip replacement.

Tumors

Bone tumors that arise within the bone itself are rare, although many types have been described. It is far more common however to have metastatic cancer which spreads to the bone from other locations.

Metastases may involve the femoral neck (the portion of the femur just below the ball), which can lead to fracture. Pain usually precedes a fracture, however, and bone scans and other tests usually reveal the tumor before fracture occurs. Sometimes a metal rod or pins are used to strengthen the involved area, and at other times a hip replacement may be used to make the patient more comfortable and preserve their ability to bear weight and walk. The five tumor types that most commonly are responsible for spreading to bone are breast cancer, lung cancer, thyroid cancer, prostate cancer, and kidney cancer.

Labral Tears

The hip socket (acetabulum) has a cartilage "bumper" or gasket that surrounds the rim. If this gasket tears, the torn cartilage may not heal on its own, leading to groin pain and mechanical symptoms such as locking and catching in the hip joint. Although many of these tears are managed conservatively and eventually heal on their own, some are debilitating and require surgery to remove the torn fragment of cartilage that is being caught inside the joint.

Trochanteric bursitis

The bursa (or sac) between muscle layers over the lateral side of the hip can become inflamed and painful. The hip pain is reproduced by pressing on the side of the hip where the bone is most prominent, and most patients report that it is uncomfortable to lay on the affected side (especially at night).

It is often associated with weight gain, injury, or repetitive inflammation through activities such as running. In a few cases, the pain can be severe enough that it causes a mild limp. This type of bursitis is very common, and many patients are relieved to learn that they do not require surgery. Instead, trochanteric bursitis is usually treated with weight loss, antiinflammatory medications, muscle massage, stretching exercises / physical therapy, and an occasional steroid injection.

Ischial bursitis

Another related problem is ischial bursitis, which is less common than trochanteric bursitis but similarly affects a small bursa that is located posteriorly in the buttocks. Specifically, this is the bony prominence that you sit on, and it often results in point tenderness directly over that spot. This gives pain in the buttock area. It is usually treated in a similar manner to other types of bursitis, with anti-inflammatory medications and occasional steroid injections if severe.

Please remember the information on this site is for educational purposes only and should not be used to make a decision on a condition or a procedure. All decisions should be made in conjunction with your surgeon and your primary care provider.