Hip Problems


Hip Infections

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One of the problems with hip replacements, is that infections of these implanted joints can become a very serious problem.

Why do joint replacement infections cause problems?

Bacteria are usually well controlled by our immune system. Once an infection is detected, our immune system rapidly responds, and attacks the infecting bacteria. However, implanted materials, like those found in a joint replacement, can allow infections to persist. Our immune system is unable to attack bacteria that live on these implants, and these infections can become serious problems. If an infection of an implant goes untreated, the problem can worsen, and the bacteria can gain such a foothold that they can become a systemic problem.

The reason infections are such a significant problem is that bacteria cannot be easily eliminated from a joint replacement implant. Despite excellent antibiotics and preventative treatments, patients with a joint replacement infection often will require removal of the implanted joint in order to cure the infection.

What is done to prevent infections of total joint replacements?

At the time of surgery, there are several measures taken to minimize the risk of infection of a total joint replacement. Some of the steps are known to lower the risk of infection, some are thought to help but not known. Among the most important, known measures to lower the risk of infection after total joint replacement are:

Antibiotics before and after surgery
Antibiotics are given within one hour of the start of surgery (usually once in the operating room) and continued for a short period following the procedure.

Short operating time and minimal OR traffic
Efficiency in the operation by your surgeon helps to lower the risk of infection by limiting the time the joint is exposed. Limiting the number of operating room personnel entering and leaving the room is thought to decrease risk of infection.

Use of strict sterile technique and sophisticated sterilization techniques
Care is taken to ensure the operating site is sterile, the instruments have been autoclaved and not exposed to any contamination, and the implants are packaged to ensure their sterility.

After the operation, the risk of developing an infection from an outside source is reduced, but there is still a risk of developing an infection from the blood stream. Because of this, patients with a joint replacement implant should take antibiotics before invasive procedures such as dental work, colonoscopies, etc. It is known that these procedures may cause a transient risk of bacteria entering the blood stream. Antibiotics will help control this and prevent joint infection.

What happens when a total joint replacement becomes infected?

When a total joint replacement becomes infected, it may loosen, become painful, and need to be removed. Unfortunately, even if the implant is washed clean during surgery, most types of infections require removal of the implant to cure the infection.

Getting an infection after joint replacement surgery?

There are several risk factors for developing an infection after a total joint replacement, but most patients have no identifiable cause for developing an infection. Some of the risk factors include:

  •     Immune deficiencies (e.g. HIV, lymphoma), or immune suppressive treatments (e.g. chemotherapy)
  •     Diabetes
  •     Rheumatoid arthritis
  •     Obesity

Joint replacement infections should be divided into early and late infections to understand this subject. So-called early infections, that occur in the weeks following surgery, may sometimes be cured with a surgical washout of the joint and IV antibiotics. Exactly how long this is true for is debated, some surgeons say only in the first 3 weeks, others believe in the first 8 weeks. What is known, is the longer away from surgery, the harder to cure an infection without removing the implant.

Late infections, usually occurring months or years after the joint replacement surgery, almost always require removal of the implant, placement of an “antibiotic spacer,” and IV antibiotics. Patients who undergo this surgery will need at least 6 weeks of IV antibiotics, possibly more, before a new joint replacement can be put back in the joint.

Once an implant is removed for an infection, can a new one be put back in?

Yes, but not until the infection is cleared. Your orthopedic surgeon, in consult with a infectious disease specialist will determine the optimal treatment schedule, and obtain periodic blood work studies to determine when the infection is likely cured. After that time, a revision replacement (replacement of a joint replacement) may be considered.

References:

RH Fitzgerald, Jr “Infected Total Hip Arthroplasty: Diagnosis and Treatment” J. Am. Acad. Ortho. Surg., Oct 1995; 3: 249 – 262.
RE Windsor and JV Bono “Infected Total Knee Replacements” J. Am. Acad. Ortho. Surg., Jan 1994; 2: 44 – 53.

Hip Replacement Loosening

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Hip replacement surgery is among the most common orthopedic procedures. This operation was performed almost 300,000 times in the United States in 1997. While the procedure has become more successful and safer, it has not been perfected. One of the most common concerns of both patients and physicians is the problem of hip replacements becoming loose over time.

Why do hip replacements wear out?

Hip replacements can go bad for a number of reasons. These include:

  •     Loosening of the hip replacement
  •     Infection of the hip replacement
  •     Breakage or wearing out of the implant
  •     Damage to the bone surrounding the implant

The most common problem with hip replacements is that they begin to loosen over time. Infections and breakage of implants are uncommon, but potentially severe complications.

What is hip replacement loosening?

Hip replacement loosening occurs over time, and can cause problems with the normal function of the hip replacement prosthesis. When a hip replacement is placed into the body, it is either press-fit into the bone, or cemented into position. Either way, it is fit tightly into the bone of the thigh (femur) and pelvis so that the implant cannot move. When implants loosen, the hip replacement can begin to move small amounts. Usually this is associated with increasing pain and loss of motion experienced by the patient.

How long are hip replacements supposed to last?

Most hip replacements last an average of 20-25 years. Some hip replacements will last longer, while other hip replacement implants can fail much sooner. Occasionally hip replacement implants will fail immediately after surgery, while you may also hear about patients who have had implanted joints for 30 or more years with no problems.

Why is hip replacement loosening such a concern?

Both physicians and patients are very concerned about the problem of hip replacement loosening because a hip replacement revision surgery (replacement of a joint replacement) is a much more difficult operation. Hip replacement revisions are often not as successful as the first operation. After revision operations, patients tend to recover less overall motion of the joint. Also, the longevity of implant decreases with each revision. Therefore, physicians tend to avoid joint replacement surgery until absolutely necessary, and try to get as much mileage out of each replacement as possible.

Why do hip replacements fail and need to be replaced over time?

As stated previously in this article, there are several causes for hip replacements to fail, or go bad. Decades ago, when joint replacement surgery was new, there were different factors that determined how long a hip replacement implant would last. Some of the earliest implants failed because the metals were susceptible to breakage or the plastics quickly shattered. Because of improvements in the strength of the hip replacement prosthesis and the strength of the fixation of the implant, the hip replacements tend to last very well once implanted.

Furthermore, with improvements in sterile technique and medical treatment of infections, the very serious complication of joint prosthesis infection has also been reduced. Now, the most common cause of joint replacement loosening is due to wear of the implant surfaces, and the subsequent weakening of surrounding bone. This problem is called osteolysis, and it causes the hip replacement to loosen over time.

What happens when osteolysis occurs?

Osteolysis is a problem that causes the bone surrounding the implant to seemingly ‘melt away’. The weakening of bone around the hip replacement is seen on x-rays, and looks as though there are holes in the bone around the joint replacement. Because of the weakened bone, the hip replacement become loose, and begins to wobble within the bone. Patients experience symptoms of pain and limitations in motion of the hip. The technical name for this weakening of bone is called osteolysis.

What is ‘cement disease’, and how is this different from osteolysis?

In years past, this problem of holes in the bone seen on x-ray was called ‘cement disease’. This name comes from the fact that initially doctors did not know the cause of the weakening of bone. Because cement was used in the hip replacements, the problem was wrongly assumed to be due to the cement, thus the name cement disease. The name stuck, although it is now known that the cement is not the problem.

How does osteolysis occur?

Osteolysis occurs as a result of wearing out of the parts of the hip replacement. Over years of use, microscopic fragments of the hip replacement cause irritation to the tissues around the implant, and begin to cause the weakening of bone. Even though modern hip replacements are made of materials that can withstand wearing out very well, even small amounts of these microscopic particles can damage the bone around the hip replacement.

How can osteolysis be avoided?

In recent years, experimentation has started to investigate whether or not alternatives to the traditional metal-on-plastic (polyethylene) hip replacements would have less loosening. New implants made of ceramic-on-polyethylene, ceramic-on-ceramic, and metal-on-metal are being investigated to determine their longevity compared to the traditional metal-on-polyethylene.

How are these new implants thought to last longer?

The new implant devices tend to have much smaller wear particles; these are the debris particles that accumulate over years as the joint wears, much like the rubber wears off your car tires. In addition to having smaller wear particles, the overall volume of wear in these implants is also less than the traditional metal-on-polyethylene implants. However, it is not known yet if these different types of implants will actually lower the rate of loosening of the implants over time. Furthermore, there may be other complications associated with the use of these different types of hip replacement implants.

Unfortunately for patients there is no definitive answer as to which type of implant is “best.” The reason for this is in order to evaluate the long-term success of these newer types of implants, studies need to continue for many more years and include more patients. Many surgeons have a strong preference towards one type of hip replacement implant, and may use this in all patients because of their familiarity with that particular implant. If you have questions about what type of implant is being used in your hip replacement, you should discuss this with your doctor.

Implant Failure

If you have a hip implant, there are several signs and symptoms to watch for if you think you may have a hip implant failure.  The signs and symptoms patients generally report include, but are not limited to:

  •     Experiencing pain and discomfort in and around the hip
  •     Pain while walking, sitting, standing or even laying down
  •     Difficulty using the hip to walk, stand, bend or step
  •     Swelling and tenderness in and around the hip
  •     Decreased mobility and movement in and around the hip
  •     Bulged or prominent lump in and around the hip area that would indicate a dislocation

The mentioned signs and symptoms are not necessarily indicative of a hip implant failure, but should be reported to a doctor or medical professional immediately as it is possible that the hip implant has become loose.  When the implant becomes loose, it can damage the bone and tissues surrounding it and should be taken very seriously.

Damaged Joints and Tissue

Another possible serious side-effect from MoM Hip Implant’s, is damage to the hip joint and damage to the surrounding tissues.

The metal on metal design can produce a great deal of metallic flakes and shards as the implant wears resulting in not only metallosis, but also damage to the surrounding joints and tissues.

As the MoM Hip Implant wears, the small metal shards and flakes that are produced move into the surrounding joints and tissues causing damage. When the process of metallosis occurs, the body attacks the metal flakes, and an enzyme is produced that can damage and harm the surrounding bones and joints. As a result, the joints become weakened and can result in more severe damage to the patient’s body.

Furthermore, there have been growing concerns that the damaged joints and surrounding tissues can make it even more difficult for the already low success rate of revision surgery to help the patient continue a normal, active life.

Dislocation or Loosening of MoM Hip Implant

One of the major problems that have been associated with MoM Hip Implant Devices is that the hip implant can become loose or can dislocate from the patient during normal activities such as walking.

Dislocation of a hip occurs when the ball, the head of the femur, pops out of the socket, the pelvic bone.

When patients experience a hip dislocation, it is generally a posterior dislocation, or backwards dislocation.  During a posterior dislocation, the hip ball pops out of the socket and the hip will be left in a fixed location inwards towards the body.

The hip can also pop out of the pelvic socket in an anterior dislocation or forward dislocation.  If this type of dislocation occurs, the individual will be left with their hip and leg in an outward position twisting away from the body.

Regardless of the type of hip dislocation, when the hip pops out of socket, it is immediately extremely painful.   Patients are unable to move the leg and are at a great risk of further serious bone, muscle, nerve and tissue damage.  Do not try to move the person if possible and seek medical attention and treatment as soon as possible.  Only a doctor or medical professional will be able to properly diagnosis and treat a hip dislocation.

The cause of a hip dislocation in a person who has not had hip replacement surgery takes a significant amount of force.  To cause a hip dislocation, the hip ball has to be physically forced out of the pelvic socket due to an impact.  Auto accidents, severe physical impacts during sports, falls and work-related accidents can create the force needed to pop a hip out of its socket.

However, individuals that received a MoM Hip implant device are at a much, much higher risk of accidental hip dislocation depending on the design of the device.

The lack of depth with some metal on metal (MOM) hip devices has been noted by experts to be the leading factor in the dislocation or loosening of the hip implant.  This risk is more likely to occur because the hip ball can slip out of the shallow hip socket much easier.  The type of problem has been more common in female patients.

A very serious side-effect of the loosening or dislocation is that when dislocation occurs, it can cause very severe damage to the surrounding muscles, tissues and bone structures of the patient.  When the hip implant becomes loose or dislocates, not only will the patient experience swelling, pain and discomfort, but the loose or dislocated implant can cause bone fractures or breaks.

Signs and symptoms of MoM hip implant failing include, but are not limited to the following:

Bone Fractures:

When the hip implant has failed or is failing, patients have been found to have sustained fractures to the bones surrounding the hip implant.  Bone fractures are a good indicator that there may be something wrong with the implant.

Dislocation of the hip implant: 

If the hip implant has become dislocated, the patient will experience severe pain and discomfort along with site location swelling.  This should be treated immediately by a doctor or medical professional to prevent further damage.

Loosening of the hip implant: 

Some patients have reported that the hip implant did not come fully out of the socket, but that they did experience very severe pain and tenderness in and around the hip area.  Patients should contact their doctors as soon as possible to help minimize the amount of damage that the hip implant could cause if it becomes fully dislocated.

The outcome for any of these side-effects is that the patients will experience these painful side-effects and will possibly have to undergo revision surgery or 2nd surgery to correct the problem(s).

The revision surgery is a corrective surgery that is even more difficult, requires as much if not more recovery time, is costly and is very painful for the patient.

Metallosis- Release of metal

Metallosis occurs when the body’s immune system responds to a metal ions that result from the metal shavings and flakes that a metal on metal (MOM) replacement hip can produce.  The body’s defenses see the metal implant as an alien object, and attempts to eliminate the perceived enemy by attacking the implant.  As a result, the implant location becomes inflamed and can even develop scar tissue.

Whenever there is a metal rubbing on a metal, there are going to be small pieces that flake off and travel into the surrounding tissue areas of the body.  These small flakes are the debris that set off the immune system response.  As a result of the body’s immune system response, muscle, tendons, ligaments and even bone structures can be harmed.  When the bone becomes damaged, the metal implant can start to loosen as well.  This loosening of the implant can be very harmful, as it can cause bone fractures, infections and if it becomes too loose, even require another surgery to repair and/or replace the metal implant.  This is called 2nd surgery or revision surgery and is very painful and requires lengthy recovery time.

Hip Revision Surgery

Hip revision surgery is a procedure that an individual undergoes to remove and replace the previous hip implant.

Hip revision surgery can be required for a number of reasons:

  • The hip implant wears out
  • Hip implant becomes loose
  • The implant becomes damaged due to injury or fall
  • The hip implant was faulty
  • Metallosis- resulting in loosening of the implant

Hip revision surgery, or 2nd surgery, is one of the more frequent procedures that ortho surgeons perform.  This is partly due to the vast number of individuals that require initial hip replacement surgery, but also because the implants do wear out and can be faulty.

The downside to revision surgery, is that it is very painful, requires just as much, if not more recovery time, and can even require bone grafts from the patient of from a donor.

Hip Revision Surgery

Definition of Hip Revision Surgery    

Hip revision surgery (HRS) or 2nd surgery, is a surgical procedure that involves the removal of the previously implanted hip replacement device(s) and replacing with new hip devices.  A consequence of a patient needing to have HRS can also include the use of bone grafts from the patient or from a donor to help stabilize and strengthen the hip area.  This can be very painful and can increase the amount of recovery time.

Reasons a Patient Would Need Hip Implant Revision Surgery

Hip revision surgery (HRS) is performed for 4 main reasons:

  • Relieving pain coming from the affected area/hip following hip replacement surgery.
  • Bringing back mobility for the patient due to previous hip replacement surgery.
  • To remove loose or damaged hip implant devices from hip replacement surgery that have become loose, dislocated or failed to prevent further pain and possible permanent harm.
  • To replace old, worn out hip replacement implants.

Hip implant devices vary in the materials that they are manufactured, and this can play a role in the life and durability of a hip implant device and also, the possibility of the patient needing revision surgery.

Hip implant devices that contain parts made of polyethylene typically become loose because wear and tear on the prosthesis gradually produces tiny particles from the plastic that irritate the soft tissue around the prosthesis. The inflamed tissue begins to dissolve the underlying bone in a process known as osteolysis. Eventually, the soft tissue expands around the prosthesis to the point at which the prosthesis loses contact with the bone.

In general, a surgeon will consider revision surgery for pain relief only when more conservative measures, non-invasive procedures, such as medication and changes in the patient’s lifestyle, are not able to rectify the problems.

For some patients, a simple x-ray will show the need for revision surgery when the hip implant has been found to be loose or dislocated or if the hip implant is causing loss of bone tissue due to wearing.

Some patients may not feel pain and discomfort at this time, but will have to undergo revision surgery to preempt future problems and pain.   However, most patients do report increasing pain in the affected hip and patient reported pain and discomfort is one of the first indications that revision surgery is necessary.

Demographics of Hip Revision Surgery Patients

The demographics of hip revision surgery patients are most likely going to be changing over the coming years.  As more and more individuals live longer and more active life-styles, more and more individuals are going to require hip replacements and possibly hip revision surgery.

Recent improvements in the techniques surgeons use along with the ever-evolving hip implant devices are making revision surgery less of an outcome for individuals that receive hip replacements.

Currently, the information on who is having total hip replacement surgery and hip revision surgery is limited, but a study of Medicare patients  found that there were 3-6 times more hip replacement surgeries than there were hip revision surgeries.

Description of Hip Revision Surgery Procedure

Hip revision surgery is hard to describe in general terms because the procedure depends on a set of factors unique to each patient. These factors include the condition of the patient’s hip and leg bones; the type of prosthesis originally used; whether the original prosthesis was cemented or held in place without cement; and the patient’s age and overall health. Unlike standard THR, however, hip revision surgery is a much longer and more complicated procedure. It is not unusual for a hip revision operation to take five to eight hours.

The most critical factor affecting the length of the operation and some of the specific steps in hip revision surgery is the condition of the bone tissue in the femur. As of 2003, defects in the bone are classified in four stages as follows:

  • Type I. Minimal bone defects.
  • Type II. Most of the damage lies at the metaphysic (the flared end of the femur), with minimal damage to the shaft of the bone.
  • Type III. All of the damage lies at the metaphysic.
  • Type IV. There is extensive bone loss in the femoral shaft as well as at the metaphysic.

The first stage in all hip revision surgery is the removal of the old prosthesis. The part attached to the acetabulum is removed first. The hip socket is cleaned and filled with morselized bone, which is bone in particle form. The new shell and liner are then pressed into the acetabulum.

Revision of the femoral component is the most complicated part of hip revision surgery. If the first prosthesis was held in place by pressure rather than cement, the surgeon usually cuts the top of the femur into several pieces to remove the implant. This cutting apart of the bone is known as osteotomy. The segments of bone are cleaned and the new femoral implant is pressed or cemented in place. If the patient’s bone has been classified as Type IV, bone grafts may be added to strengthen the femur. These grafts consist of morselized bone from a donor (allograft bone) that is packed into the empty canal inside the femur. This technique is called impaction grafting. The segments of the femur are then reassembled around the new implant and bone grafts, and held in place with surgical wire.

A newer technique that was originally designed to help surgeons remove old cement from prostheses that were cemented in place can sometimes be used instead of osteotomy. This method involves the use of a ballistic chisel powered by controlled bursts of pressurized nitrogen. The ballistic chisel is used most often to break up pieces of cement from a cemented prosthesis, but it can also be used to loosen a prosthesis that was held in place only by tightness of fit. In addition to avoiding the need for an osteotomy, the ballistic chisel takes much less time. The surgeon uses an arthroscope in order to view the progress of the chisel while he or she is working inside the femur itself.

After all the cement has been removed from the inner canal of the femur, the surgeon washes out the canal with saline solution, inserts morselized bone if necessary, and implants the new femoral component of the prosthesis. After both parts of the prosthesis have been checked for correct positioning, the head of the femoral component is fitted into the new acetabular component and the incision is closed.

Diagnosis

In most cases, increasing pain, greater difficulty in placing weight on the hip, and loss of mobility in the hip joint are early indications that revision surgery is necessary. The location of the pain may point to the part of the prosthesis that has been affected by osteolysis. The pain is felt in both the hip area and the thigh when both parts of the prosthesis have become loose; if only the femoral component has been affected, the patient usually feels pain only in the thigh. As was mentioned earlier, however, some patients do not experience any discomfort even though their prosthesis is loosening or wearing against surrounding structures. In addition, a minority of patients who have had THR have always had pain from their artificial joints, and these patients may not consider their discomfort new or significant.

In general, diagnostic imaging that shows bone loss, loosening of the prosthesis, or wearing away of the joint tissues is an essential aspect of hip revision surgery—many orthopedic surgeons will not consider the procedure unless the x-ray studies reveal one or more of these signs. X-ray studies are also used to diagnose fractures of the hip or dislocated prostheses. In some cases, the doctor may order a computed tomography (CT) scan to confirm the extent and location of suspected osteolysis; recent research indicates that CT scans can detect bone loss around a hip prosthesis at earlier stages than radiography.

Infections related to a hip prosthesis are a potentially serious matter. Estimated rates of infection following THR range between one in 300 operations and one in 100. Infections can develop at any time following THR, ranging from the immediate postoperative period to 10 or more years later.

The symptoms of superficial infections include swelling, pain, and redness in the skin around the incision, but are usually treatable with antibiotics.  With deep infections, antibiotics may not work and the new joint is likely to require revision surgery. One American specialist has said that the chances of salvaging an infected prosthesis are only 50/50.

Preoperative preparation

Certain health conditions or disorders are considered contraindications for hip revision surgery. These include:

  • a current hip infection
  • dementia or other severe mental disorder
  • severe vascular disease
  • poor condition of the skin covering the hip
  • extreme obesity
  • paralysis of the quadriceps muscles
  • terminal illness

Patients who are considered appropriate candidates for hip revision surgery are asked to come to the hospital about a week before the operation. X rays and other diagnostic images of the hip are reviewed in order to select the new prosthesis. This review is called templating because the diagnostic images serve as a template for the new implant. The surgeon will also decide whether special procedures or instruments will be needed to remove the old prosthesis.

Aftercare

Aftercare for hip revision surgery is essentially the same as for hip replacement surgery. The major difference is that some patients with very weak bones are asked to use canes or walkers all the time following revision surgery rather than trying to walk without assistive devices.

Risks

Risk factors

Factors that lower a patient’s chances for a good outcome from hip revision surgery include the following:

  • Sex. Men are more likely to have poor outcomes from revision surgery than women, other factors being equal.
  • Age. Older patients, particularly those over 75, are more likely to have complications following revision surgery.
  • Race. African Americans have a higher rate of complications than Caucasian or Asian Americans.
  • Socioeconomic status (SES). Patients with lower incomes do not do as well as patients in higher income brackets.Presence of other chronic diseases or disorders.
  • Obesity. Many surgeons will not perform hip revision surgery on patients weighing 300 pounds or more.
  • Genetic factors. Recent British research indicates that patients who carry an inflammation control gene known as TNF-238A are twice as likely to require replacement of a hip prosthesis as those who lack this gene.

Specific risks of hip revision surgery

Risks following hip revision surgery are similar to those following hip replacement surgery, including deep venous thrombosis and infection. The length of the patient’s leg, however, is more likely to be affected following revision surgery. Dislocation is considerably more common because the tissues surrounding the bone are weaker as well as the bone itself usually being more fragile. One group of researchers found that the long-term rate of dislocation following revision surgery may be as high as 7.4%.

Normal results

In general, hip revision surgery has less favorable outcomes than first-time replacement surgery. The greater length and complexity of the procedure often require a longer hospital stay as well as a longer period of recovery at home . The range of motion in the new joint is usually smaller than in the first prosthesis, and the patient may experience greater long-term discomfort. In addition, the new prosthesis is not expected to last as long. The life expectancy of implants used in first-time hip replacement surgery is usually given as 10–15 years, whereas revision implants may need to be removed after eight to 10 years.

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