News Category: Hip

For 30 years researchers have looked for ways to reduce bone loss after total hip replacement (THR). The stiff implant results in atrophy of the bone. This reaction occurs as the bone reacts to the mismatch in materials where the implant meets the bone. Bone resorption of this type is called stress shielding.

Many studies have tried to identify the cause of stress shielding. Stiffness of the femoral stem could be the problem. The femoral stem fits down into the femur (thigh bone). It is attached to the new ball-shaped femoral head that fits into the hip socket.

Or perhaps the cause of bone resorption is the type of material used to make the implants. Other scientists have studied the shape and angles of the stem looking for an answer. The goal is to find a way to reduce postoperative bone loss. Stress shielding can cause fractures further compounding the problem.

New femoral designs are the subject of this article. The authors ask the question, Do they influence stress shielding? Only studies using dual-energy X-ray absorptiometry (DEXA) were included. DEXA allows measurement of bone loss both before and after surgery.

The results of different types of stem design were reviewed. The following findings are reported:

In the last five years, surgery for total hip replacement (THR) has changed with smaller incisions and minimally invasive surgery (MIS). In this study a direct comparison was made of the two-incision THR and the mini-posterior THR.

The same surgeon did all surgeries. The same anesthesia and rehab program were used with all patients. Twenty-six (26) patients were included. They had the two-incision method done on one hip. Then later they had the mini-posterior approach. Having both hips replaced one after the other is called a staged-bilateral procedure.

After each operation, the patients kept a diary to keep track of their progress. They reported how long they used an assistive device (cane, walker) when walking. They also wrote down when they started driving again and when they went back to work. Other milestones included walking up and down stairs and walking half a mile.

After six months they filled out a survey. They told the researchers which operation they preferred and why. Two-thirds of the patients preferred the mini-posterior THR. Two patients had no preference. The rest liked the two-incision method better. Early recovery, better cosmetic results, or both were named as reasons for the preferences.

The authors report no difference in functional recovery between the two operations. Since the two-incision method is technically more difficult and doesn’t have better results or patient preference, surgeons may want to consider using the posterior approach to THR.

Results of this study suggest there is still a high failure rate with hip resurfacing. This is true despite changes in the way the procedure is done. Surgeons from the Center for Hip and Knee Surgery in Indiana report long-term results of 62 patients.

Each one had an Indiana conservative hip prosthesis. This is a type of surface replacement that is no longer being used. Some of the problems with this prosthesis have been improved with newer designs.

But femoral failures may still be a problem with hip joint resurfacing that hasn’t been addressed. The authors advise caution before adopting hip resurfacing as a better choice over total hip replacement.

The results of this study show femoral neck fractures and femoral implant loosening two or three decades later. These problems may not have been corrected with the newer hip resurfacing techniques.

Most of the changes in today’s hip resurfacing address problems with the acetabular (socket) side of the hip. Metal-on-metal now replaces the plastic liner to avoid failure from polyethylene wear. The components are placed into the bone without cement, which has helped with the problem of loosening.

The authors conclude that even though hip joint resurfacing helps preserve bone, failures are still too common to adopt this as a routine procedure. Comparing joint resurfacing with total hip replacement (THR) shows better long-term results with the THR.

Which is better for independent, mobile older adults who fracture their hips: hemiarthroplasty or total hip replacement (THR)? Hemiarthroplasty refers to replacing just the broken femoral component.

This includes the round ball at the top of the femur (thighbone) with a stem that fits down into the femur. The acetabulum (hip socket) is not replaced. THR removes and replaces both sides of the joint (femoral head and acetabulum).

Patients with a displaced fracture of the femoral neck were divided into two groups. One group had a hemiarthroplasty. The other group had the THR. Short-term results were measured after three years.

Walking distance and function were the main outcomes compared. X-rays were also taken and viewed for any erosion of the bone and narrowing of the joint space. Results showed that the THR group walked further and had better function than the hemiarthroplasty group.

The authors also reported that both groups had decreased function after surgery compared to before the hip fracture. Walking distance was especially decreased in the hemiarthroplasty group.

Painful acetabular erosion was the most likely reason for this change in walking ability in the hemiarthroplasty group. Erosion appears to be linked with higher activity levels in younger patients.

The findings of this study suggest THR is better than hemiarthroplasty for active, healthy adults. Further study is needed to make the same treatment comparison for less active, mentally impaired older adults.

Concern about medical problems is increasing as more and more adults are having total hip replacements (THRs) and total knee replacements (TKRs). Heart attacks, pneumonia, and blood clots are a few of the most common causes of serious problems. Death from these complications after orthopedic surgery of this type can also occur.

Studies are ongoing to find out how often these problems occur. The first 30 to 90 days are the most critical. The number of patients affected is on the rise as the number of younger patients getting joint replacements increases. Results so far show the following incidence:

Sometimes total hip replacements (THRs) fail and must be taken out. Pockets of bone loss can occur during this process. Impaction grafting reviewed in this article is a way to treat this problem.

Shaved bits of donor bone called an allograft are used to fill these bone defects. These tiny pieces of bone work well because they are easy to shape to fit the hole. When packed in tightly, the graft supports the implant until native (new) bone can form to stabilize the hip.

The process of filling the defect layer-by-layer and tamping down the bone is called impaction grafting. Metal mesh may be needed to shape a structure or scaffold. The graft fills in and around the mesh.

A trial implant is used to check the position and measure leg length. When everything is ready, cement is injected to seal everything together.

Long term results and problems after impaction grafting are also presented. Implant survival after 12 to 15 years is 85 per cent. Loosening of the implant in the remaining 15 per cent requires another revision surgery.

Infection is the most likely problem after bone grafting. Femoral (thighbone) fractures can occur during the operation from the force of the hammer used to tamp down the bone. Fractures can occur afterwards if the quality of bone graft is poor.

Impaction grafting can be used successfully when a THR must be revised and there’s been a loss of bone stock during removal. Young patients are especially good candidates for this procedure. Impaction grafting has also been used with bone fractures to fill in the fracture line and speed up healing.

Increased airport security has consequences for patients with metal implants. Anyone with a pacemaker is not required to go through a metal detector screening. A pat-down screening will be needed.

Joint replacements may or may not set off the metal detector. In this article, Dr. Ostrum, Chief of the Orthopaedic Trauma Unit at Cooper University Hospital in New Jersey looks at this problem.

One person with a joint replacement may trigger an alarm at one airport that doesn’t get triggered at another. The factors that affect metal detection may include:

Doctors at Mayo Clinic report 21 cases of intraoperative acetabular fracture in total hip replacements (THRs). There were a total of 7,121 patients in the study. It is rare that this type of problem occurs during the procedure. The acetabulum is the socket portion of the hip that is replaced.

In this study, only uncemented cups were fractured. There were three general cup types used. The groups were based on shape and diameter. These included elliptical monoblock, elliptical modular, and hemispherical modular.

The two cup designs that fractured most often were the Implex elliptical monoblock and the Peripheral Self-Locking (PSL) elliptical modular. Most of the cups were stable and further treatment wasn’t needed. The surgeon placed some extra bone graft along or into the fracture line. X-rays showed healing occurred with bone in-fill.

The authors give surgeons specific instructions about using elliptical monoblock cups since most of the fractures occurred with this design. They suggest the stress of putting this type of cup into the hip can lead to fracture. The surgeon must be prepared for this event even though it doesn’t happen very often.

In this report, surgeons from the University of Missouri School of Medicine present their surgical technique for a total hip replacement (THR). They used a two-incision method that is minimally invasive (MI).

All 89 patients received an uncemented THR. The surgeon used a special imaging called fluoroscopy to guide them. Fluoroscopy is very helpful in checking to make sure the position of the hip and implant is correct.

A step-by-step description of the operation is given with some tips on how to reduce complications. For example, the patient’s hip is placed in a slightly flexed or bent position. This is designed to relieve tension on the nerve along the front of the thigh.

And fluoroscopy was used to find the exact spot for the incision. This step can also reduce the risk of nerve damage. At the end of the study, the authors suggested that fluoroscopy shouldn’t be relied upon. The surgeon is better off using anatomic landmarks to get the best implant positioning. Other advice offered included placement of reamers, use of lighting, patient positioning, and specifics about cup alignment.

The results for these 89 patients are compared with the outcome of 96 THRs using a single mini-incision technique. All operations were done by the same surgeon. The two-incision MI method had a 10 per cent reoperation rate.

This was compared to a six per cent repeat surgery rate for the standard one-incision method. Likewise, there were many more other problems reported and linked with the two-incision MI compared with the one-incision procedure.

Overall results improved with practice and increased experience using the two-incision approach. The authors conclude that even with fluoroscopy to guide the operation, the complication rate is high with a two-incision MI. Patients must be chosen carefully for this procedure. The surgeon must have special training and practice on cadavers before doing this on live humans.

Joint resurfacing is a logical way to reduce pain and restore function in young, active patients with severe arthritic changes of the hip. Hip resurfacing arthroplasty is a type of hip replacement that smooths the surface. Then a protective or replacement metal cap is placed over the bone at the top of the femur (thigh bone).

There are many advantages to this treatment. It preserves the bone. It restores the leg length. It can even give the patient improved biomechanics. If the replacement cap wears down, there’s still enough bone left to change over or convert later to a total hip replacement.

American orthopedic surgeons haven’t been as quick as surgeons in Europe to use this treatment method. There are reasons for this delay. Femoral neck fractures and osteonecrosis (death of bone) are two problems that occur with hip joint resurfacing.

There are also concerns about high metal ion levels with metal-on-metal hip surfaces. And studies show that loss of oxygen occurs at the femoral head during this operation. When the blood supply doesn’t come back, osteonecrosis occurs. Without an adequate blood supply, the hip is also at increased risk for fracture.

More American surgeons may use this treatment option when results are better and follow-up studies show which patients can benefit from the operation.

Total hip replacements (THRs) have been around now for almost 30 years. Over time, the surgery and surgical techniques used have changed and improved. The shift from fully cemented to uncemented implants is slowly taking hold.

Researchers around the world have studied the long-term results of cement use in THRs. In this study, researchers review a meta-analysis of 20 studies on THRs. They found that the type of cement is important for long-term performance. Specific types of cement are linked with lower rates of revision.

Sweden, Norway, Australia, and the United States have large databases including the records from 1000s of total hip patients. From the information on the databases, we know that the rate of revision varies from country to country.

Sweden has two and a half times more revisions for uncemented THRs compared to cemented. Revision rates are much higher in Australia for uncemented THRs. Norwegian surgeons report equal results between cemented and uncemented for a wide range of patients. The U.S. may have the highest rate of revision surgeries reported for both types in patients 65 years old or older.

The authors of this report conclude that not all patients need one kind of implant method. Surgeons must be prepared to perform both cemented and uncemented hips. More studies are needed to identify patients who would benefit most from both kinds.

Study, time, and experience has brought a new gold standard in total hip replacements (THRs). Cemented femoral implants are being replaced with uncemented components. The femoral component consists of the round head of the femur (thighbone) with a long, tapered stem that sets down into the femur.

Why the switch? Because results of long-term studies show increased rates of loosening over time in cemented stems. Thirty years of study at the Indian Research Foundation have resulted in data collected on 6,533 THRs.

Uncemented stem implants outperformed cemented stems. There were no cases of loosening for the uncemented group. This 100 per cent survivorship means there was excellent biologic fixation of the implant in the bone.

The authors conclude uncemented stems are the first choice for most patients. This includes young or older patients with good or bad bone. The shape (straight or crooked) or the condition of the femur doesn’t seem to matter. Patients with hip fracture or replacements on both sides can also benefit from uncemented THRs.

In order to stay strong, bones need load and compression spread evenly across the bone. When bone is removed and replaced with a hip prosthesis, the implant changes how the load is placed on the femur (thighbone). This is called stress shielding.

Stress shielding can lead to thinning of the bone and decreased bone mineral density. Changes in the shape and amount of bone from stress shielding can occur. The result may be bone loss around the implant. That could be a problem later on if the total hip replacement has to be revised.

Using 10 cadavers with a total hip replacement (THR) on one side, researchers analyzed the bone after death. They compared changes in bone around the implant on the total hip side to bone on the nonimplanted side. Bone loss and bone density were measured.

They looked at patient activity level and walking ability before death. They also factored in age, implant size, and length of time the patient had the implant. The shape of the bone was measured using computer analysis of the bone cut cross-wise. This is called a cross-sectional analysis.

The authors report that reduced activity and to a lesser extent, patient weight were directly linked to greater bone loss. Age, implant size, and length of time the implant was in place didn’t seem to make any difference in bone density.

Patients who limped put a smaller load on the implanted side compared to the nonimplanted hip. Patients who could walk more than six blocks without a limp had less bone loss after THR. This study supports the importance of activity (especially walking) after THR.

As adults in the United States live longer, more and more are having hip or knee replacements. Older adults with joint implants are also at increased risk for falls and fracture.

Twenty-four (24) women with hip or knee replacement and fracture of the femur from a fall were included in this study. They were all treated with the Less Invasive Stabilization System (LISS). The LISS is a locking plate device that was designed for use with fractures of the distal femur (near the knee).

The authors expected to find a lower rate of complications after treating the fracture with an LISS compared with treatment using other fixation devices. The LISS was used with 10 fractures located just below the hip prosthesis, nine above the knee implant, and five in patients with both a total hip and a total knee replacement on the same side.

The results were so favorable that none of the authors want to use or study other treatment options. Problems occurred in only one patient. This was a five per cent complication rate compared to 15 to 57 per cent reported with other devices.

New fractures, failure to heal, infections, and implant loosening are common problems for patients with a fracture after joint replacement. There were no infections and only one fixation failure for the women in this study. This study shows the usefulness of the LISS for femoral fractures in older adults with joint replacements.

Surgeons from the New York University Hospital for Joint Diseases report on the results of an uncemented stem hip replacement. A customized lateral flare cementless femoral stem was used in 35 young patients. Patients were followed for at least five years. Some were reexamined up to 12 years later.

The authors report excellent results with this type of hip replacement in a younger age group. All patients were younger than 55 years old. Other studies report high rates of mechanical failure with cemented implants. Loosening and reaction to the cement were major problems.

As a result, changes were made in the shape and design of the femoral stem to eliminate the use of cement. A grit-blasted and coated upper surface of the implant gives a surface that bone can adhere to and grow around. The lower part of the stem down inside the femur (thigh bone) is smooth with large grooves. The design of this part of the stem helps limit contact with bone.

There was a low rate of infection and loosening of the lateral flare stem used in this study. This was a positive finding in favor of uncemented stems for younger, active patients. It is proposed that the lateral flare (wider at the top along the outside edge) helps reduce the load on the bone when standing on the leg.

Exercise has been shown to reduce pain and improve function for patients with hip osteoarthritis (OA). But the effects don’t last if the patient stops exercising. Many patients end up with a total hip replacement (THR).

In this study, physical therapists look at the effect of mobilization and manipulation of the hip combined with exercise. Manual physical therapy (MPT) plus exercise has been studied with OA in general. This study is different because it focuses on just the hip.

Seven patients ages 52 to 80 years with hip pain or a diagnosis of hip OA were included. Range of motion (ROM), strength, and function were measured before and after treatment.

All patients had limited hip flexion and internal rotation. Weakness of the muscles that externally rotate and abduct (move the leg away from the body) was reported. Younger patients had problems with bike riding, golfing, driving, and skiing. Older patients were unable to garden and had trouble with stairs and daily activities.

Treatment included thrust or nonthrust MPT based on the therapist’s exam of each patient. Description of these techniques is given in this study. A program of home exercises was given to improve strength and flexibility.

All seven patients showed changes in hip ROM, pain, and function. Results were maintained six months later. Patients were able to return to their favorite activities.

The authors conclude physical therapy may be able to help patients with hip OA avoid having a THR. The cost savings is upwards of $30,000. More studies are needed to find out which MPT methods work best for patients with hip pain.

More and more adults with arthritis are having total hip replacements (THR) at a younger age. Revision surgery is also on the rise because the implant has a limited life and wears out.

In this study, researchers at the University of Virginia Health System report on the results of rehab for both primary (first) and revision THR. They included 255 primary THR patients and 147 cases of revision THR.

Tests of function were given all patients at the time of admission. Patients were tested again after surgery. Activities measured included stair stepping, walking, dressing, wheelchair mobility, and transfers. After surgery, everyone was enrolled in therapy three hours a day for up to two weeks.

Results showed lower scores for patients with a revision THR. This was especially true for those who had a hip joint infection. Patients having a revision THR stayed in the hospital longer. Total rehab hospital charges were higher for the revision group, too.

Revision patients were less likely to go home from the hospital. Pain and other complications resulted in more revision patients going to skilled nursing facilities (SNFs) before going home. Patients who come to the hospital with lower levels of skill are also more likely to go to a SNF after primary or revision THR.

One final result reported in this study was the negative effect of abductor brace use after surgery. These braces are designed to keep the legs apart. The goal is to reduce the risk for hip dislocation.

However, it appears that using this brace limits the patient’s movement. Patients who used abductor braces had higher hospital costs and were more likely to need further care before discharge to home. The authors suggest further study to look at the true need for the abductor brace following primary or revision THR.

Adult patients with severe hip problems present new challenges for the orthopedic surgeon. This study presents the second report on a group of 20 patients. Each one had severe developmental dysplasia or total hip dislocation.

All received a porous-coated shell called the acetabular component. This shell or socket covers the head of the femur and prevents it from slipping out or dislocating. A porous surface is rough (not smooth). This feature makes it possible for bone to grow into the implant, helping to lock it in place.

In the first study, these patients were followed for five to eight years. In this second report, follow-up continued for another nine years. X-rays were taken to look for wear, movement of the implant, or changes in the bone. The amount of wear of the plastic liner was also measured.

The authors report 19 patients still had the same acetabular shell in place after 16 years. This in itself is an excellent long-term outcome. Overall results were rated from poor to fair to good to excellent with a fairly equal number in each category. Two hips were revised because of implant loosening or liner wear.

This study supports the use of cementless sockets in patients with developmental hip dysplasia or total dislocation for better wear and longevity. Results do deteriorate over time but the average implant lasted 15 years with good to excellent results reported.

This is a retrospective study of 66 patients who were diagnosed by arthroscopy with a hip labral tear. Retrospective means the researchers looked back after the diagnosis was made to see if there was any way to tell what the problem was. For example, did all the patients have a limp? Did they all have hip and/or groin pain? Was there any one clinical test that was positive for every patient to point to a labral tear?

The labrum is a rim of cartilage around the edge of the acetabulum (hip socket). It helps keep the joint stable and in place. Recent studies have shown that many degenerative conditions affecting the hip cause this kind of tear. Young and middle-aged adults are affected most often.

Diagnosis of labral tears can be difficult. The wrong diagnosis is often made, and time is wasted on the wrong treatment. Sometimes surgery is done on the wrong body part. The results of this study may help change that. The authors report 95 per cent of the patients had a positive impingement sign. Almost as many had moderate to severe groin pain.

A positive impingement sign occurs when the patient has groin pain when his or her hip is bent to 90 degrees. The upper leg moved in and across the body applying pressure or compression through the joint. Many patients reported night pain and walked with a limp. Hip or groin pain was worse with activity, especially when pivoting over the foot.

X-rays should be taken but may not show the problem. The only way to know for sure is arthroscopy to look inside the joint. The authors suggest a trial of conservative treatment for no more than two months. At that point, if symptoms are the same or worse, then an injection of a numbing agent into the hip or more advanced imaging studies may be helpful.

Once the diagnosis is confirmed, the authors suggest surgery as the only successful way to deal with painful labral tears. Several operations used to repair a hip labral tear are discussed. Each one is based on the type and location of the tissue damage.

Surgeons at the University of Iowa Hospitals and Clinics have been tracking total hip replacement (THR) patients for the last 25 years. In this study, the results of a single surgeon’s cases using the Charnley hip implant are reported. Results after 10 and 15 years were reported in earlier studies.

Age of the patient, type of operation, and condition of the joint and implant after surgery were all recorded and compared over the years. The number of patients who had to have a second (revision) operation was also reported. Most revision surgeries were done because of implant infection, loosening, or dislocation.

Only about 15 per cent of the original patients in this study were still alive at the time of the 25-year follow-up. The average age of those still living was 82 years old. For the patients who had died, 88 per cent still had the original hip replacement. It was working well at the time of their deaths.

For the living patients, X-rays were taken to measure the rate of bone wear in the hip. Overall results for two types of methods to cement the hip in place were also compared. The authors report the Charnley THR with hand packed cement works well for most patients in the long-term. There were no differences in results using different cement techniques.

Patients who received the first cementless implants will be the focus of another study. Different types of implants and surgical techniques will continue to be compared over five, 10, 15, and 25 year periods of follow-up.