News Category: Hip

For up to 26 years, doctors in Japan examined patients with surgically repaired hip dysplasia. Each patient received the same total joint replacement. The implant was cemented in place and extra bone was grafted to form a proper socket. The results are reported in this study.

Developmental hip dysplasia is a condition some people are born with. The hip socket is too shallow to provide a “rooftop” or cover for the head of the femur (the thighbone). In previous studies, the results of this operation varied quite a bit. The authors of this study set out to find factors that affect the results of hip joint replacement for developmental dysplasia.

All patients were examined every year. Hip pain, walking distance, and range of motion were measured each time. They found that the two most important factors are patient age and graft size. A cemented hip implant with added bone graft to cover the head of the femur work best in older patients (more than 50 years old).

Success is also greater if the bone graft makes up less than 50 percent of the cover for the femoral head. If more is needed, the socket is moved. Long-term results are good when these two guidelines are followed. None of the patients reported pain and further surgery wasn’t needed.

The authors conclude that younger patients should have surgery to save the original joint. They also need instruction about safe activity levels. A total hip replacement for developmental hip dysplasia is usually reserved for older patients.

Rheumatoid arthritis (RA) of the hip may be treated by replacing the joint with a total hip arthroplasty (THA). However, the socket side of the joint implant sometimes gets infected or comes loose and has to be repaired. The procedure to do this is called acetabular revision.

Acetabular revision in patients with RA is a challenge for the orthopedic doctor. Poor bone quality and loss of bone leaves little for the surgeon to work with. A bone graft may be needed. A new method to do this is called impaction bone grafting. Bone dust and very fine bone shavings are combined to strengthen the weakened bone. The graft is pressed into the hipbone using special surgical tools. The plastic (polyethylene) replacement cup is then cemented in place.

A study from the Netherlands reports the results of this revision method. The authors say that when a THA must be replaced in patients with RA, this form of bone grafting combined with a cemented cup has good results. A small number of patients (35 hips) were followed for an average of 12 years.

The revisions held up well for 90 percent of the patients. Even after five to seven years, the number of infections or loose implants was very low. Some patients had X-ray signs of loosening, but they reported no symptoms or problems. The authors think replacing lost bone is a good solution for patients with RA who need acetabular revision.

Nobody likes to think a new hip joint replacement can dislocate, but it can. Most of the time, surgery is not needed to fix the problem. The hip can be put back in place, and a brace or cast can hold it there. The patient is advised to avoid certain motions and positions for up to six weeks.

However, surgery is sometimes needed. This is the case when the hip dislocates more than once. Doctors don’t like to do another operation. Up to 50 percent of these surgeries fail, and the hip continues to dislocate.

This study looked at the use of one particular replacement part called a constrained acetabulum. This is the lining that goes inside the hip socket. Researchers used five different methods to put the liners in place. They report the results for each method.

The constrained acetabulum holds the ball-shaped top of the thighbone (the femoral head) in the socket. The design of the constrained acetabulum helps to keep the femoral head from dislocating. This implant also improves the results of a second operation in the event of another dislocation.

Certain steps taken during surgery help keep this type of implant from dislocating. Pressurized cement fixes the implant in place. Doctors may add stitches to the back part of the hip joint to block the femoral head from slipping out the back of the joint.

Patients are advised to take precautions in order to prevent another hip dislocation. When the surgery is done from the back of the hip, the hip mustn’t be bent past 90 degrees (as when bending forward at the waist). Patients must not turn or roll the hip inward, and they must avoid crossing the legs, even at the ankle.

The implants used in total joint replacement procedures can be held in place with cement. Some surgeons routinely use cement to implant new hip joints. Holes are drilled in the acetabulum, the pelvic socket that receives the cup portion of the new hip joint. A special tool called a pressurizer is used to settle the cup in place. The force from the pressurizer can cause the cement to ooze out around the edges of the cup. This is called cement extrusion (CE).

Most of the time, patients have no symptoms from CE. However, in some patients, a small amount of cement in the wrong place can cause problems. Irritation of a nerve can cause burning. Nearby blood vessels are also at risk of being damaged. No one has studied how much CE is too much, or how often CE causes problems in people receiving a cemented hip implant.

The goal of this study was to find a way to measure how much and how far the cement travels beyond the edges of the implant. X-rays can be used to show large amounts of CE and are less costly than MRI (magnetic resonance imaging) scans. Only one patient in the study had poor X-rays and had to be left out. Almost half of the remaining patients (for a total of 111 hips) showed CE on X-rays. No one needed treatment for symptoms from the CE.

The authors of this study conclude that CE is common. No one knows yet how many patients with CE will have problems. Studies have not yet shown how much cement can squeeze out before symptoms occur. This new method of measuring CE will help researchers answer these questions in the future.

Getting a good night’s sleep is important at any age. A restful night goes a long way toward good physical health and mental function. Arthritis pain can rob people of healthy sleep patterns.

This study monitored sleep in patients before and after total hip replacement. As the researchers expected, most of the patients (75 percent) reported much better sleep after the operation.

Sleep was measured using a sleep diary and a motion recorder. Patients wrote in a diary the time they went to bed, times they got up at night, and daytime napping. The motion recorder was worn like a watch. Its software recorded data about movement, time in bed, and actual sleep time.

Both tools were used for five days in the month before the operation, and again three months after the operation. Results after surgery showed that if patients woke up, it was for some other reason than hip pain. The patients and researchers think that relief from arthritis pain is the reason for the improved sleep.

The findings show that sleep improves after a total hip replacement. The patients sleep longer, wake less often, move less during sleep, and wake up refreshed more often. The authors conclude that better sleep after total hip replacement leads to improved day-to-day function and quality of life.

Doctors have the option of using acrylic cement when replacing joints. The cement binds the implant to the surrounding bone. The implant has to be able to take loads that are placed on the limb. It is thought that the cement helps the new joint to share these loads with the bone.

Any surgery increases the risk of infection. This is especially true during joint replacement surgery. Why not mix an antibiotic with the cement? This is exactly what doctors did back in 1970. How and when doctors use this concoction raises new questions.

To find answers, doctors of the Musculoskeletal Research Center at New York University reviewed the use of this form of treatment. They found that there isn’t an accepted way to use antibiotics in joint implant cement. Some doctors always use it, while most save it for joints that have to be operated on a second time (called joint revision surgery). Revision surgery is often recommended if the implant comes loose or gets infected.

There is concern about the regular use of antibiotics. When bacteria come in contact with these drugs, they can change and become resistant to the drug. Besides bacterial resistance, other problems can occur with the use of this product. The antibiotic can cause the cement to lose its strength. Some antibiotics prevent the bone, ligaments, and other soft tissues from healing. Researchers are trying to find the best mixture that releases the drug slowly and won’t slow down healing after joint replacement surgery.

The mixture of antibiotics with joint cement isn’t needed for every joint replaced. Future cement products may be stronger with a slow release of antibiotic over time. The goal is to find an antibiotic that lowers the infection rate and doesn’t have to be removed.

Total hip replacements are becoming more common as people live longer and are faced with severe arthritis. Doctors can’t just cut the hip open and put the new joint in to replace a damaged hip joint. Some preparations are needed before a total hip implant is put in place.

The head of the femur (thigh bone) is removed. The doctor makes a hole down the femur bone for the stem of the implant to fit. Special tools are used to cut and remove bone. The most commonly used surgical tool for this task is called a toothed broach.

Another tool, the smooth tamp can also prepare the bone for the implant. The tamp can be used to move the bone to the side and pack it down instead of cutting and removing bone. Doctors are concerned that the smooth tamp method will increase a patient’s risk of hip fracture.

In this study, the smooth tamp was compared to the toothed broach. Cadavers (human bodies preserved after death) were used. Researchers prepared one hip with a smooth tamp and the other hip with a toothed broach. They made sure that the bone was equal in density in all the cadavers.

This study showed that using a tamp caused more fractures. The fractures were more severe and occurred with less force than with a broach. The broach was able to slice thin layers of bone with less force. This appears to have reduced the risk of fracture.

The authors conclude that the toothed broach preserves bone when preparing for a hip joint replacement. Long-term implant survival depends on getting a good fit of the implant stem into the bone canal. Finding the best tool for the job is the focus of this research group. The tamp and broach have one tool shape and may not work for all implant types. Each tool must be studied separately.

Total hip replacement surgery, also called total hip arthroplasty (THA), is becoming a familiar procedure in many places around the world. There are several different ways to operate. The doctor may open the hip from the front, side, or back. Not everyone agrees on the best way to do this.

One of the most popular methods is called the posterolateral approach. In this case, the cut is made along the back (posterior) and side (lateral) of the hip. It’s a simpler way to get to the hip. However, there’s a risk of having the new hip dislocate with this method.

One way to prevent hip dislocation with a posterolateral approach is called posterolateral reconstruction. In this operation, the joint covering (capsule) and nearby tendons and muscles are stitched back in place. The hip is turned out slightly while the tissues are stitched up. The idea is to restore strength and stability to the joint.

Japanese doctors studied the effect of this reconstruction on hip range of motion (ROM) and muscle strength. They found that with soft tissue reconstruction, strength is greater without a loss of ROM. The group who had THA without reconstruction had equal ROM, but less strength.

The authors of this study suggest a posterolateral THA with soft tissue reconstruction. They feel that this extra step improves joint stability and muscle force without limiting joint ROM.

Sometimes, hip joint replacements come loose. When this happens, another operation may be needed. This is called a revision.

A total hip joint replacement has two parts. The top of the thighbone (femur) with the ball or head is one part. The other half is formed by the socket or cup, which fits into the hip socket, the acetabulum. When just the cup needs to be revised, the procedure is called acetabular revision. Many cup implants are held in place with cement. But during acetabular revision, the bone may be too smooth and too hard to accept cement.

In this study, an extra large cup was used without screws. The cup was pressed into the bone, which is why it’s called a press-fit cup. The extra surface area gives the cup more contact area. A good fit means that no screws are needed to hold it in place. The friction between the bone and the cup helps cause bone growth. The cup becomes embedded into the bone. This can start to happen as early as two weeks after the revision.

Screws are avoided for many reasons. Screw heads may push into the cup and scrape against the ball portion of the implant. The screw holes leave spaces for tiny bits of metal to pass through. Any opening can leave the joint at risk for infection. When the screw gets loose, the cup can also move or migrate. Movement between the bone and the implant makes the joint unstable.

The authors of this study determined that extra large cups can be used with good results in cases of acetabular revision. Obtaining a good fit without needing screws avoids many problems.

Hip dislocation can occur after a total hip replacement. The joint may be new, but problems can still come up. In fact, dislocation is the second most common reason why patients have a second hip operation after a joint replacement. Loosening of the implant is the first.

Dr. Barrack, MD, a professor at Tulane University School of Medicine, studied causes of hip dislocations. He looked at implant design and positioning because these are two factors doctors can control. This article gives a summary of recent findings.

Each implant has two parts: the femur (thighbone) and the acetabulum (cup or socket). The shape of each piece and placement in the hip affect motion. Certain types of implants give better motion with less risk of dislocation.

A circular-shaped neck in the femoral implant decreases motion. It’s best to use a trapezoid shape (two sides that are parallel to each other). Using a larger head improves motion and gives a more stable joint. There may be slightly more wear with a larger head size.

Researchers using computer modeling show the best angle and position for both parts of the implant. The acetabular cup on the socket side can be turned to match the angle of the femur. The result is a more stable hip joint with less chance of dislocation.

The goal of many studies is to find a hip joint replacement that won’t dislocate. This is difficult given the large number of implant types to choose from. The author offers orthopedic surgeons helpful information when choosing design and position of implants for patients.

Orthopedic surgeons are always looking for ways to make joint replacement surgery more successful. One method is to apply joint cement to the implant. Unfortunately, the cement sometimes loosens its grip on the stem that fits into the top of the thighbone (femur). The implant no longer fits snugly and may eventually require a second operation to revise the hip joint.

Doctors think that the cement loosens because tiny air pockets form pores in the cement around the stem. Heating the stem before insertion has shown some promise in the past. These authors did tests in a laboratory to see how well heating the implant worked. They heated implants to at least body temperature before applying the cement. After the procedure was done, the cement was checked for pores. The implant was also tested for strength.

Preheating the stem proved effective in decreasing pores in the cement. This approach strengthened the bond between the cement and the implant by more than 50 percent when compared to stems that were implanted at room temperature. After simulating the effects of aging, the preheated implants showed 155 percent greater strength. The cement also set more quickly when the stem was preheated.

The authors conclude that preheating the stem can help prevent cement loosening in artificial hip joints. They recommend that preheating be considered for other types of implants as well.

A diastrophic dwarf is someone who is short because of abnormal growth and development of the bone and cartilage. Diastrophic means a “bent or curved” position of the bones. This can cause changes in the bones and in the way the joints line up.

When the hip joint is affected, the condition is called diastrophic dysplasia. The result is often disabling pain and loss of motion. Walking with a limp is common. The distance a person can walk may be limited by pain.

Doctors in Finland studied the effect of replacing both hips in adults with diastrophic dysplasia. Joint implants don’t last a lifetime, yet adults with this condition have a normal life span. There is a concern that doing the surgery early in life will eventually lead to a problem later on with the implant.

Hip joints on one or both sides are replaced with implants when severe pain keeps the patient from walking and doing everyday activities. The authors of this study report good results. Three-fourths of the patients were pain-free a year after the operation. One-third was able to walk without a limp and without the need of a walking aid.

These patients face unique problems associated with hip replacement. The implant may more often become infected and come loose. Fractures, nerve damage, and dislocation can occur. Many patients with diastrophic dysplasia have other deformities of the spine, knees, and feet, which can make recovery more difficult.

Even so, the authors conclude that total hip replacement is advised for patients with diastrophic dysplasia. Even fairly young adults can be included. In this study, patients ranged in age from 27 to 56 years old. The gains in function and decreased pain levels make total hip replacement a good treatment choice for this condition.

Hip joint replacement is the way to go when the ball, or head, on the top end of the femur (thighbone) is damaged and can’t be fixed. Arthritis affecting the hip joint is one cause of this type of damage. Another is avascular necrosis (AVN). AVN happens from a loss of blood supply to the top of the femur. The result is death (necrosis) of the femoral head. AVN commonly occurs from hip fractures where the broken ends of the bone actually shift–or displace. A displaced fracture near the top of the femur is routinely treated by replacing the head of the femur.

Doctors have two choices for replacing the head of the femur. They can replace the entire hip joint (ball and socket) by performing a total hip replacement (THR). Another option is to replace only the head of the femur, a procedure called hemiarthroplasty. The implant used for hemiarthroplasty comes in two styles. The round head of the femur that fits into the hip socket can be one piece. The other type, called a bipolar implant, has a stem with a ball on the end that swivels. The surgery to replace the head of the femur with a swivel implant is called bipolar hemiarthroplasty.

In this study, doctors compared the results of THR with bipolar hemiarthroplasty. They used patient reports and X-rays as the measures of success. Each patient had a THR on one side and a bipolar hemiarthroplasty on the other side. It turns out that most of the patients preferred the side with the THR. In addition to less pain on the side with the THR, patients reported better walking ability on that side.

Yearly follow up X-rays showed that the bipolar implant tended to cause the cartilage in the socket to break down. Another consideration is a higher rate of second operations needed after a bipolar hemiarthroplasty. However, the chances for hip dislocation after surgery are higher for THR compared to bipolar hemiarthroplasty.

The authors conclude that THR is a more involved operation. For cases when the head of the femur is damaged, THR showed better results than bipolar hemiarthroplasty. The authors’ conclusion agrees with those of other similar studies.

Arthritis can cause muscle weakness and reduce the ability to exercise. Studies also show that the more physically fit you are before surgery, the faster you’ll get better after surgery.

If this is true, should we set up exercise programs before and after surgery? According to this study of people having a total hip replacement (THR), the answer is yes. Exercise improves early recovery after a THR.

Patients who exercise before and after the operation tend to be less stiff and have more motion compared to patients who don’t exercise. Patients in the exercise group started the program eight weeks before surgery. They came back to the clinic three weeks after surgery and exercised until 12 weeks after their operation.

Exercise included warm-ups, strengthening, pool therapy, and aerobics. Arm strength was also included to help with bed to chair transfers and using a walker or crutches. Patients in the exercise group showed increased strength in both hips. Patients who didn’t exercise stayed the same or had slight decreases in strength.

The good effects of exercising before surgery were still present six months later. Patients were able to take care of themselves with less help and got around faster and sooner. Improved pain levels, stiffness, and function in patients needing a new hip can help them return more quickly after surgery to daily activities, recreation, and work.

Dislocating a hip is painful, but treatment can help. The doctor will put the patient to sleep and move the joint back in place. Sometimes the same hip dislocates more than once. There are three directions a hip can go: forward (anterior), sideways (lateral), or backwards (posterior).

Repeated dislocations can be a painful problem for the patient. Even when no pain is present, there’s a worry that the joint will dislocate and the leg will give away without notice. This is the first report of a recurring hip dislocation solved by an operation called a periacetabular osteotomy.

“Osteotomy” means to cut through the bone. In this operation, the doctor cuts around the hip socket (acetabulum) and aims the socket in a new direction. The new position holds the ball at the top of the thighbone in the joint.

This case is unusual. The patient had nine past anterior dislocations of the same hip. She’d had one operation to repair the problem, but it didn’t work. This 35-year old woman was unique in that she had other risk factors for recurring hip dislocation.

She had a condition called systemic lupus erythematosus. Lupus is an inflammatory disease affecting many parts of the body. In this case, the patient was taking drugs for lupus that cause loose joints. And there was a problem with the way her hip was formed, making it possible for the hip to slip out of the socket easily.

After nine hip dislocations, her doctor performed the periacectabular osteotomy. The operation worked.

The doctor in charge of this case points out that a hip that dislocates over and over needs careful review. Before doing surgery, the hip joint must be studied for any unusual changes. The right operation can help prevent multiple dislocations.

New technology is everywhere, including the operating room. Total hip replacement (THR) surgery is changing because of better equipment. In the past, the doctor made a very large cut through skin, muscles, and other soft tissues to get to the hip joint. Being able to see the whole hip socket is important when replacing the joint.

A new navigation system allows the doctor to make a smaller opening and implant the new joint without seeing the whole joint. This method uses an image-guided navigation system called HipNav. A computer, software, and infrared visual system track the position of the pelvis and tools during the operation.

Surgeons in this study looked at two groups of patients getting THRs. One group had the typical full-length incision, while the other group had the “mini-incision” method. They found that the mini-incision group had better results at three and six months after the operation. There were no major differences between the two groups after one year.

The use of a less invasive method of THR is just as safe and effective as the older method. The biggest problem is getting the cup portion of the new joint in the right position. If the surgeon has any doubt about its placement, the doctor can make a longer cut during the operation.

Some hip replacements wear out faster than others. In fact, the same joint implant used in a group of adults will vary in its wear pattern.

Researchers aren’t sure why this happens. It might be the patient’s weight, and therefore, the load on the joint. It could be activity level that affects the rate of wear. This study looked at these two factors in patients with hip replacements on both sides, which is called bilateral total hip arthroplasty.

A small group of patients with the same type of arthroplasty was studied. Each patient had the same operation, cup design, and replacement parts in both hips. No one with a limp was allowed in the study to prevent uneven wear patterns in one hip.

The authors of this study thought that by matching all replacement parts, they would reduce the differences in wear on the implant. They measured the first hip replaced and compared it to the second hip arthroplasty.

As it turned out, the difference in wear rates between the first hip and the second was drastic. In most cases, there was up to a 75 percent difference in the wear between the two implants. With all things considered, identical implants in the same patient with the same activity levels showed marked differences in wear.

The authors conclude that wear and tear on hip arthroplasties depends on more than a patient’s weight and activity. At least 40 percent of the differences in wear rate come from other factors that include patient age, joint angle, and bone slivers or metal particles caught between the implant and the joint surface. Doctors can’t assume that identical hip replacements will have the same result. This is true even for patients having bilateral hip arthroplasties.

At least half of the adult human body is made up of water. This fluid is in every cell, between the cells, and inside the blood. Not having enough body water leads to dehydration. In older adults, dehydration is one of the most common reasons for going to the hospital.

According to this study, adults who have a hip or knee joint replacement are especially at risk for dehydration. So are adults with a hip fracture. Most patients in this study showed positive test results for dehydration. Notably, they also required twice as long to recover before going home.

Even before a health problem occurs, older adults are at risk of dehydration. This is because the body’s ability to detect thirst reduces with age. Living alone and depression add to this problem. Diseases such as diabetes, kidney failure, or bladder infections also play a role in dehydration. Taking diuretics (water pills) for high blood pressure can get rid of too much fluid. This puts the heart patient at risk of dehydration.

Dehydration has physical and dollar costs. The authors of this study report that millions of dollars are spent every year as a result of dehydration. For example, it cost Medicare nearly 500 million dollars in 1991 for care related to fluid loss. Almost half of all patients on Medicare who are hospitalized with dehydration die within one year.

The authors point out the need to prevent dehydration in anyone having orthopedic surgery. As adults in the United States get older, more patients will be having joint replacements and hip fractures. Preventing dehydration will shorten hospital stays and reduce costs.

In rare cases, infections can invade a child’s hip joint. The result is a hip joint that does not grow and develop properly. These children commonly grow up to need a surgery called total hip replacement (THR).

But THR is not a simple surgery in patients who had childhood hip infections. After infection, the bones that form the hip may be weak and poorly shaped. The muscles and other tissues around the hip may also have become tight and weak. Doctors are concerned about the possibility of reinfection. And these patients need THR when they are still young and active, making problems after surgery more likely.

These doctors followed up on 170 THR surgeries done in patients who had childhood hip infections. The patients’ average age when they had the hip infection was seven. Their average age when they had THR was about 42. The authors looked at the THR results for 10 years after the surgeries. They write in detail about the different types of hip damage, implants, and results. Here are some highlights:

Epidemiologists study the big picture of disease. They look at data to find out how a disease affects the population as a whole. Epidemiology doesn’t just produce facts about disease. It also gives information about how the health care system works.

This article is about the Epidemiology of total hip replacement (THR) in the United States. The authors analyzed data from Medicare records of people 65 or older over the course of one year. They focused on patients who had THR or revision THR surgery, but not because of hip fractures, hip infections, or cancer. The authors discovered some interesting facts about THR.