Hips

 | September 1, 2006

Hips

Watch a ballet dancer and you can appreciate the hip joint's ability to move in almost any direction, if only the muscles are willing. Like the shoulder, the hip is a ball-and-socket joint with a remarkable range of motion. It has basically the same joint design as that used to maximize your car's steering.

Like your knee, your hip is a network of bones, cartilage, ligaments, and muscles. People tend to perceive of their hips as just the part of the bone you can feel on the side of your body. It's important to recognize that the hip is actually a large region that extends to your thigh and groin. A malfunction anywhere in this large area can cause pain and decrease mobility.

Bones

Key bones in the hip include the ilium, the acetabulum (a deep socket in the pelvis), the thighbone (femur), and the trochanter. Your hip is designed for a difficult task: supporting the full weight of your body while allowing movement in all directions. To accomplish this, the top of the thighbone is shaped in a smooth ball that fits snugly within the acetabulum (see Figure 6). In women, the pelvis is wider and the bones are lighter than in men, but the hip joint structure is the same. Thanks to the perfect fit, along with the slick cartilage coating the bones and the lubricating synovial fluid produced by the joint's lining, the friction between the ball and socket in a healthy hip is less than that of two ice cubes rubbing together.

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Cartilage

The acetabulum is cushioned and deepened by a vital rim of cartilage called the labrum.

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Ligaments

The hip joint is surrounded by a strong joint capsule made up of four ligaments, the most important of which is the iliofemoral. These tissues keep you from moving the hip to an extreme position that could dislocate the joint.

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Muscles

Muscles in the thigh and lower back help stabilize and move the hip. The large gluteus maximus muscle in the buttocks extends the hip when you move your leg backward or to the side. The hamstrings also extend the hip, while the hip flexors (a muscle complex that runs from the lower back to the front of the thigh) help flex the hip when you lift your leg to the front. Muscles of the groin and abdomen are also involved in hip movement.

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Bursae

As in the knee, places in the hip where tendons, muscles, and bones meet are protected by small liquid-filled sacs called bursae.

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Evaluating hips

During an examination, the doctor will ask questions about pain and other symptoms. Be sure to describe sensations in the entire leg: A hip problem may cause pain in the front, side, or back of your hip, in the groin, and even in the knee. Mention any physical labor or sports you participate in and falls or injuries you have experienced. Even if you landed on your knees rather than your hip, you may have jolted your hips. (See "Evaluating knees" for a list of questions your doctor may ask.)

During the physical examination, the doctor will watch you walk to observe unevenness or changes in your gait. Hip pain or muscle weakness can change how you walk. Speak up if any portion of your stride hurts. The doctor may examine your shoes for signs of abnormal wear. The doctor may also observe how far you can flex your knee toward your chest and extend your hip out behind you, and how readily you can move your leg out to the side (abduction) and across your midline (adduction). As you lie on your back, the doctor will measure how far you can rotate your hip externally (letting the knee fall toward the outside of your body) and internally (letting your knee turn toward your midline). As you move or try to resist pressure applied by the doctor during different maneuvers, the doctor will assess pain, muscle strength and restrictions, and any grinding or snapping in the joint.

Along with the hip exam, the doctor will examine the position of your pelvis, compare your leg lengths, test nerve function in your legs, and check your feet and ankles for swelling that might indicate impaired circulation. He or she will also examine your spine for curvatures or conditions (such as a pinching of the sciatic nerve) that can cause hip pain.

In addition, the doctor is likely to use x-rays or other imaging techniques to diagnose hip problems (see "Testing for knee and hip problems").

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Overuse injuries

Muscles of your thighs, abdomen, and buttocks attach at your hip joints. You can injure these muscles and nearby tendons when you overexercise or participate in activities that you don't do regularly or for which you lack sufficient conditioning.

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Hip muscle strains

With age, hip muscles become prone to strains, particularly the hamstrings in the back of the thigh, the hip flexors in the front, and the adductors on the inside of the thigh. A mild strain involves overstretching the muscle; a moderate strain, mild tearing; and a severe strain, a full tear.

The hip flexor muscles help you lift your leg in front. These may be strained by heavy lifting or pushing, biking (especially if your seat isn't high enough), high kicking, martial arts, playing soccer with lots of kicking, or running with knees lifted high.

You may strain your hamstring by moving from stillness or gentle action into full-out activity, especially if you are not conditioned or warmed up — for instance, if you suddenly dash to prevent a child from running into the street. Hamstring strains are common in sprinting, jumping, soccer, and tennis; they can also occur with overzealous flexibility moves, such as attempting to do splits.

Treating hip muscle strains. When you seek medical help, the doctor will ask about your activities and how the pain began. It may hurt when the doctor pulls your knee to your chest or rotates your hip inward during the physical exam.

Initial treatment consists of rest and ice along with pain medications such as ibuprofen or naproxen. If the pain is severe, you may need crutches to take weight off the area. After swelling improves, usually in several days, you can begin gentle stretches, using heat and ice as needed. Rehabilitation after hip muscle strain involves strengthening and stretching the muscles, improving endurance, and training before returning to any physical activity.

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Tendinitis

Hip tendinitis is inflammation of a tendon caused by microscopic tears. Tendinitis of the hip flexor muscles such as the iliopsoas in the muscles occurs commonly in older people whose gait has been thrown off by related problems in the spine, knees, ankles, or hips. In younger people, it develops more often in athletes, such as gymnasts and dancers, who repeatedly lift the leg while their hip is rotated out. Runners are particularly vulnerable when they train on hills and increase their mileage rapidly.

During your examination, the doctor checks for pain by pushing against your thigh as you flex your hip (moving your knee toward your chest while you sit or lie down). You will need to tell your doctor about the location of the pain and what kinds of activities seem to trigger it.

Treating tendinitis. Initially, the goal of treatment is to reduce inflammation and make you more comfortable, using ice and NSAIDs such as ibuprofen and naproxen. After a few days, you can try heat. During the first few days, don't put any unnecessary pressure on the area. Sleep on your unaffected side with a pillow between your legs. Once swelling has subsided, you can gently begin to exercise the area to improve the strength and flexibility of the muscles. If you know what activity led to your tendinitis, avoid it for at least 10 days, and when you do begin again, start at a lower intensity.

If your condition does not respond to treatment, your doctor may order an MRI or other test to rule out a stress fracture or tumor.

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Bursitis

Bursae sometimes become inflamed, creating stiffness and pain (see Figure 8). Hip bursitis is more common in women and in middle-aged and older people.

Trochanteric bursitis. This painful condition can result from a single hard fall on your hip or the accumulation of minor stresses — from small injuries, excess pressure on one hip when you walk or run (from scoliosis, other joint damage, or unequal leg lengths), carrying a shoulder bag that hits against the side of the hip, and even lying on one side of the body for an extended period (perhaps after another injury). In women and in middle-aged and older people, particularly those who exercise only sporadically, a tight iliotibial band is likely to cause pain in the hips (see "Iliotibial band syndrome"). The pain is usually located about one inch behind the trochanter (the bony bump on the side of your hip). A tight IT band can mimic the symptoms of trochanteric bursitis; in some cases, it can cause it.

Ischial bursitis. This condition occurs when the bursa under one of the ischia (the bones you sit on) becomes inflamed. As suggested by its nicknames "weaver's bottom" and "tailor's seat," it can occur from prolonged sitting on a hard surface, as well as from a fall or repeated friction during bicycling or rowing.

Iliopsoas bursitis. This form of bursitis affects the protective sac that lies between the front of the hip joint and the iliopsoas muscle, one of the hip flexors. It can be associated with rheumatoid arthritis or osteoarthritis of the hip, or it may be brought on by overdoing activities that require repeated hip flexing (such as soccer, ballet, jumping hurdles, or running uphill).

Treating bursitis. During your medical exam, the doctor assesses the range of motion in your hip joint and presses on the hip bursae to check for tenderness. You may have an x-ray or MRI to help the doctor rule out conditions that sometimes cause similar symptoms, such as fracture, bone spur, arthritic joint damage, tumor, or an area of dead bone. If an infected bursa is suspected (a rare circumstance), the doctor removes some fluid from the sac for testing.

Treatment includes rest and ice along with pain relievers such as ibuprofen or naproxen. You'll need to reduce your activity until the symptoms subside, usually in a few weeks. Physical therapy with specific stretching and strengthening exercises may be recommended. For trochanteric bursitis, this may involve iliotibial band stretches (see Figure 7). For iliopsoas bursitis, you may stretch and strengthen the hip flexors and rotators. For ischial bursitis, you may temporarily use a cane to take pressure off the affected hip. Talk with your doctor or physical therapist about how to do these exercises.

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Labral tear

A dislocation or other injury of your hip can rip the cartilage of the labrum. And doctors have recognized that milder pivoting injuries — even those that go unrecognized at the time — can also cause labral tears (see Figure 9).

A labral tear may cause immediate symptoms or may not bother you, even while it sets the stage for later joint problems. An injured labrum loses some of its ability to protect and cushion the cartilage lining the socket beneath it, and a roughened edge may begin to scrape against cartilage on the ball of the hip joint, leading to osteoarthritis. In proper position, the labrum creates a seal that helps keep the hip joint properly lubricated. Losing this seal invites cartilage damage.

A labral tear is more common in someone born with an abnormally shallow hip socket, a condition that puts more pressure on the rim.

To diagnose a labral tear, the doctor extends your hip fully and puts it through a range of motions to check for pain, clicking, and restricted movement. The hip may hurt when the doctor turns it inward, and it may click when the doctor pulls it to maximum extension. The findings are often not definitive, however, and confirming the diagnosis can be difficult. Standard x-ray and CT scans are not helpful because they do not reveal cartilage abnormalities, and a standard MRI does not have enough resolution to show a torn labrum. These techniques may help rule out other problems, however.

A technique in which gadolinium (a metal dye) is injected into the hip joint before an MRI is highly accurate in detecting labral problems. The most definitive way to diagnose a labral tear is by looking directly into the joint using arthroscopy. This procedure requires an experienced surgeon and sophisticated equipment.

Treating labral tear. Nonsurgical treatment of a labral tear includes pain relief medication, physical therapy, and temporary use of crutches until symptoms subside. The tear itself will not heal or disappear, but usually your pain and other symptoms will improve. If your condition interferes with movement or your doctor thinks it will lead to joint degeneration, you may undergo arthroscopic surgery, during which the surgeon confirms the diagnosis and removes the torn and frayed areas, usually all in the same procedure. After surgery, you use crutches for several days. You can resume normal activities after about two weeks and begin participating in sports at about six weeks. If labral damage occurs because of a hip problem that has been present from birth, you may need more extensive surgery to reshape the area.

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Hip fracture

One in seven women fractures a hip at some point in life, as does 1 in 17 men. For many of these people, life will never be the same. A year afterward, only 41% regain their previous ability to walk — even if they were alert, healthy, and mobile beforehand.

Without active effort to reduce the risk among older people, hip fractures and disability will continue to surge as life expectancy increases and people spend more time in the high-risk years. Nine of 10 hip fractures result from falls, with most others from car accidents or other traumas. The risks for hip fractures can be divided into two categories — those that make you more likely to fall and those that make your hip more likely to break if you do fall.

The risk of hip fracture is higher in someone with low bone density. Very low bone density results in the condition known as osteoporosis (see Figure 10). Someone with severe osteoporosis can actually break a hip just from the stress of walking. The risk of hip fracture rises with age in both men and women, with more than 90% of fractures occurring in people over 50. A man's risk is equivalent to that of a woman about five years younger. Fracture risk is higher for people on dialysis and remains high the first few years after a kidney transplant.

A possible hip fracture needs immediate evaluation. An x-ray is likely to show a fracture if one exists. But if it doesn't and if your symptoms strongly suggest a fracture, an MRI can reveal a break that has not moved out of place or a fracture involving the hip socket rather than the femur.

The two most common types of hip fracture involve the femur. A femoral neck fracture occurs in the horizontal section of the femur, about 1–2 inches from the ball of the hip joint. An intertrochanteric fracture occurs in the femur 3–4 inches below the ball of the hip. Fractures of the hip socket are less common.

The severity of a hip fracture is judged by how far the bone has moved out of place. If the bone has cracked but not separated, it is described as nondisplaced. If the bone has shifted slightly, it is classed as minimally displaced. If the bone is completely detached at the break site, it is said to be displaced.

Treating hip fracture. The goal of treatment is to reconnect the broken bone and hold it in place so the hip works properly until it has time to heal — about three months. Surgery within 24 hours is usually necessary to make this repair. If you must wait for surgery, the hip may be held in traction (using weights to extend the muscles around the hip).

If you have a femoral neck fracture in which the pieces are not displaced, the orthopedic surgeon may connect the bone with surgical screws. If the bone has moved well out of place, or if you are older and not active, your surgeon may replace the head of the femur with a metal device, a procedure called a hemiarthroplasty or partial hip replacement. Or the surgeon may perform a total hip replacement (see "Hip replacement procedure") if pre-existing arthritis is noted. An intertrochanteric fracture is stabilized by screws and a device that holds the broken bone in place while allowing the ball to move normally in the hip socket.

In general, nonsurgical treatment for hip fracture is reserved for people who are at high risk for serious complications during surgery and whose medical condition is such that imperfect healing of the fracture would be acceptable — for example, someone who is already bedridden and not in much pain.

After surgery, it can take several months for the hip to heal completely. Initially, you'll use crutches or a walker, putting weight on the leg only as permitted by the doctor. How soon you can put weight on the leg depends on the type of pinning or other device used in the repair. The goal of rehabilitation is to get you back on your feet as soon as possible. In the first few days of rehabilitation, you learn to use assistive devices safely and begin muscle strengthening and range-of-motion exercises in bed and while sitting. Gradually you'll begin to walk and perform more vigorous exercise with the physical therapist.

To prevent another fall, your physical therapist will work to help you develop a secure, balanced gait and will suggest other safety measures. To help prevent a second fracture, you should be evaluated for osteoporosis and treated if necessary.

Your doctor may also prescribe a drug from a class of antiresorptive agents called bisphosphonates, which increase bone density by slowing the rate of bone loss. Drugs in this class include risedronate (Actonel), alendronate (Fosamax) — which are available in daily and weekly doses — and ibandronate (Boniva), which comes in daily or monthly doses.

These drugs have been shown to reduce the risk of spine, wrist, and hip fractures by 40% to 50%. They are generally well tolerated, but they can irritate the esophagus and stomach, causing heartburn and nausea. Another drawback is that once a person starts taking them, he or she needs to continue taking them for life or risk a sharp drop in bone density.

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Risk factors for hip fracture

Numerous factors can put people at risk for hip fracture.

For women and men:

a close relative with osteoporosis who broke a hip or wrist

a diet poor in calcium and vitamin D

excessive alcohol consumption

smoking

a broken bone after age 50

overactive thyroid

kidney failure

sedentary lifestyle

general poor health

taking medications that can make bones more fragile (such as corticosteroids, anticonvulsants, aluminum-containing antacids, and thyroid medication).

For women only:

menopause before age 45

dieting or exercising during the reproductive years to the point where menstrual periods ceased

height over 5 feet 8 inches at age 25.

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Osteoarthritis of the hip

The hip joint is one of the most common sites for osteoarthritis. This condition begins with a small amount of cartilage disintegration, resulting in some local inflammation. The process continues as the cartilage erodes and bone spurs form.

While there is no ironclad way to prevent this from occurring, most doctors believe the best way to avoid hip osteoarthritis is to maintain a healthy lifestyle. In particular, keeping a healthy weight from early adulthood on and exercising regularly to maintain muscle tone will help keep your hip joints strong.

Hip osteoarthritis is more common among the elderly and those who have had hip injuries. Obesity also places extra stress on the hips; in the Nurses' Health Study, an ongoing study of thousands of women, those who were in the heaviest group at age 18 had five times more risk of developing severe hip osteoarthritis than those who were in the lightest group. Recreational physical activities, including running, have not been shown to raise the risk of hip osteoarthritis.

To diagnose your condition, your doctor asks you about your symptoms and performs a physical exam. Although an x-ray will not show cartilage damage, it may reveal other changes related to osteoarthritis, including decreased joint space, bone spurs, and cysts. A blood test for inflammation helps rule out other possible causes of your symptoms.

Treating osteoarthritis of the hip. The first line of treatment for mild osteoarthritis of the hip is a combination of over-the-counter or prescription pain relievers such as ibuprofen and acetaminophen. Using acetaminophen along with ibuprofen or another NSAID makes it possible to use a lower dose and thus minimize side effects. NSAID medications have a variety of side effects so it is important to discuss your personal health risks with your doctor when considering long-term use. Steroid injections are also sometimes used.

Exercise is important to help keep your hip joint limber. Water exercises are particularly suited for improving the hip's range of motion and promoting strength and flexibility in the muscles surrounding it. For exercise to be effective, you must make an ongoing commitment to exercising several days a week. In studies from the Netherlands, a 12-week supervised exercise program significantly improved pain and function in people with osteoarthritis of the hip or knee. If the people did not continue to exercise, however, the benefits disappeared within nine months. Talk with your doctor or physical therapist about a full program of hip-strengthening exercises.

Resting the hip when you feel pain is also important. A cane or a walking stick held in the hand opposite your bad hip can take pressure off the joint as you walk or do other activities that tend to aggravate the pain (see "Easing the strain with a cane"). Most people limit stair climbing and cut back on walking longer distances. When bathing, use a shower stool and hand-held nozzle to avoid standing.

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Review Date: 2006-09-01

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