Hip arthritis is inflammation of the joint which frequently causes pain, stiffness, and limitations in activities. There are many possible causes of pain in the hip region, including back pain, bursitis, tendonitis, and other things unique to your physiology and health history. Chronic pain specific to the hip joint most commonly involves damage to the cartilage. As a ball-and-socket type joint, the hip provides many degrees of motion. This broad range of movements requires diffuse healthy cartilage to allow painless and smooth motion.
As cartilage deteriorates in the hip joint, the underlying bone becomes exposed. The irregular surfaces and the inflammation associated with bone moving against bone, leads to pain and stiffness. The ball in socket joint becomes more like a square peg in a round hole. Pain typically occurs in the groin or on the side of the hip.
Occasionally, hip pathology will present as knee pain. As hip arthritis progresses, limping and leg length discrepancies may worsen. A hip examination and radiograph is the most common method of diagnosing hip arthritis.
Other pathologies such as avascular necrosis or congenital hip dysplasia can also be diagnosed in a similar fashion. Nonoperative treatments can temporarily make symptoms more tolerable, but typically the arthritis and associated pain progresses.
Arthritis refers to inflammation, pain, swelling, or stiffness in a joint which is most frequently caused by wear and tear in the cartilage surface of bones. When this occurs, knee arthritis tends to progress. The knee is a naturally hard-working joint, but its function can be compromised by body weight, and other physiological stresses, which can accelerate such wear patterns.
Many times, knee deformities ensue causing the legs to become either bowed or knock-kneed. These deformities alter leg weight-bearing distribution and can also contribute to the progression of arthritis.
The knee joint provides motion in the lower leg to perform activities such as walking, climbing, pivoting, and bending. This flexibility inflicts many forces and stresses across the knee joint. The ability to maintain these functions requires the knee to be comprised of numerous tissue types:
These components of the knee work in conjunction to provide smooth, painless, and stable knee motion for everyday activities. However, injury to any of these parts of the knee can lead to pain.
CAUSES OF KNEE PAIN
Acute knee pain may begin after an identifiable cause or may be of recent or sudden onset. The most common acute knee injury types are:
Acute knee pain is most commonly treated nonoperatively with rest, ice, elevation, and anti-inflammatory medications.
Pain which does not resolve is considered chronic pain. While there are multiple possible causes of chronic pain, osteoarthritis (the wear and tear of cartilage) is the most common cause.
Evaluation by a physician with radiographic studies is the most reliable method of diagnosing arthritis.
As cartilage is lost at the end of bones, the underlying bone is exposed. Motion in the joint now causes pain, swelling, stiffness, and sometimes catching or locking. Prior trauma or inflammatory arthritides can also damage cartilage, and the end result is similar. As the condition progresses, daily activities become more difficult to complete and lifestyles are limited.
Because the arthritic process cannot be reversed, eventually joint replacement options may be necessary.
As reliable as joint replacement surgery can be, a variety of problems can occur which creates trouble for the joint replacement patient. We’ll go through a few of the most common issues and outline the general treatment algorithms below, but if you or someone you love is experiencing problems with a previously replaced hip or knee, we recommend a thorough in-person evaluation. Such a consultation begins with the patient gathering some critical information dating back to the time of the original surgery. The items we need include:
It’s important we receive this pertinent information before your consultation so we will be best prepared to answer your questions during your visit.
MOST COMMON HIP REPLACEMENT PROBLEMS
All hip implants, including hip resurfacing devices, can dislocate. Fortunately, the rates of dislocation are declining. Dislocations are termed either anterior or posterior, based on the route the ball takes to come out of the joint. The surgical technique used often predicts the direction of potential instability, but not always. If one of the anterior approaches to the hip is employed (direct anterior, modified Watson Jones, anterolateral, direct lateral), the risk of anterior dislocation after surgery is around 1% overall. The chance of a posterior dislocation is small if an anterior approach was used. Conversely, if a posterior approach is used (mini-posterior, standard posterior), the anterior dislocation risk is very small and most dislocations will be posterior. The actual risk of a posterior dislocation is dependent on many factors, however, if a capsular repair is done after the implants are placed, the chance is less than 1% both in our experience and as reported by others:
The treatment for a hip that repeatedly dislocates usually involves revision surgery. In many cases, the position of the implants can be improved to prevent recurrent problems. Repairing the capsule and careful attention to postoperative precautions maximize the chances of success. If hip instability appears many years after a replacement, this can be due to major wear of the artificial bearing. Placement of a new bearing is the easiest revision operation to recover from. This being said, further dislocation problems do occur after revision surgery and sometimes require the use of constrained liner devices in which the ball snaps into the socket component.
Sometimes implants that were originally solidly attached become loose, either due to cracking of bone cement or proliferation of wear debris. Early loosening of implants usually reflects failure of bone-ingrowth into porous coating, due to either inadequate early stability or poor bone blood supply. Intra-operative fractures can contribute to this problem, as can smoking and other health risks. Implant loosening requires revision surgery to correct the problem. If there is bone loss associated with the fixation failure, the surgery to correct the situation may be extensive and the recovery lengthy.
Leg Length Inequality
All patients should understand that determining and achieving equal leg lengths in total hip replacement surgery is not an exact science. Occasionally, the leg lengths are not exactly what the patient or we would desire. This is usually because achieving equal leg lengths needs to take a back seat to obtaining a stable hip. Our data suggests that we achieve leg lengths within 5 mm of being equal in 90% of our patients. When the leg lengths are not equal after the operation, it is sometimes necessary to wear a lift in the heel of the shoe. A lift is required in about 5% of cases.
Our record with leg lengths requires substantial preoperative thought as well as intra-operative wisdom on the part of the surgeon. At times, lack of planning and/or inexperience results in a noticeable discrepancy. This problem may be partially correctable if addressed early, but it is difficult to rectify after the passage of more than a few months. The conservative treatment involves the use of a shoe lift. If the opposite hip requires surgery, a leg length inequality can be solved at that time.
Corrosion and Cobalt Ion Release
Sometimes the metal implants used in hip replacements can release metal ions into the hip joint. Titanium is well-tolerated but some ions such as cobalt are not. The cobalt ions are picked up by the body’s scavenger cells and they become overly active, digesting tissue and bone inside the hip joint. Sometimes the damage can be extensive and irreparable. The primary symptoms are new pain and/or stiffness in a replaced hip. This issue has proven to be a major problem with metal against metal bearings, but it occurs with metal-on-plastic bearings as well if corrosion occurs at the junction between the metal head and the neck of the femoral component. Fortunately, excessive cobalt can be detected by a simple blood test and usually the problem is rectified by revising the metal head to a ceramic version. Dr. Dearborn has extensive experience treating this particular problem in patients with a variety of implant types and has presented our clinical research on this topic around the globe.
The cause of pain after hip replacement surgery, in the absence of problems evident on x-rays, can be difficult to find. Obtaining the history and careful physical examination in the office are very important in this situation. Infection is the first potential source of pain to rule out, which is typically accomplished via blood tests and removal of fluid for analysis. If infection is confirmed, further surgery is usually required. In many cases, initial removal of the implants is required in order to resolve the infection.
Other causes of hip pain in the presence of satisfactory appearing x-rays, include stiff uncemented femoral components and various soft tissue sources. Injection of local anesthetic and steroid medication into structures such as the iliopsoas tendon sheath can be both diagnostic and therapeutic. In some cases, tendons can rub over the edges of prominent implants, and revision surgery is required to remove the source of the impingement.
MOST COMMON KNEE REPLACEMENT PROBLEMS
In most cases, knee range-of-motion is improved after a total knee replacement. Patients who obtain less than 90 degrees of knee flexion are uniformly dissatisfied after surgery. Risk factors for postoperative stiffness include below average preoperative motion, intra-operative technical factors, and postoperative pain management difficulties.
The treatment for unsatisfactory knee motion involves further surgery. Scar tissue must be removed and in some cases the implants need to be revised. Evaluation in the office will be necessary to discover the cause of the poor motion which will, in turn, guide the treatment.
Over time, polyethylene bearings are subject to wear and potential failure. If there is no implant loosening or damage to the metal bearing, exchange of the worn liner can be the straightforward solution. In certain severe, chronic wear situations, metal against metal contact can occur, resulting in metal bearing damage and the shedding of metallic debris. Complete implant exchange is usually required in this setting, which often leads to bone loss necessitating the use of special revision implants.
Sometimes implants that were originally solidly attached become loose, either due to cracking of bone cement or proliferation of wear debris. Implant loosening requires revision surgery to correct the problem. If there is bone loss associated with the fixation failure, the surgery to correct the situation may be extensive and the recovery more lengthy than for a simple liner exchange.
The cause of pain after knee replacement surgery, in the absence of problems evident on x-rays, can be difficult to find. Obtaining the history and careful physical examination in the office are very important in this situation. Infection is the first potential source of pain to rule out, which is typically accomplished via blood tests and removal of fluid for analysis. If infection is confirmed, further surgery is usually required. In many cases, initial removal of the implants is required in order to resolve the infection. Other causes of knee pain, in the presence of satisfactory appearing x-rays, can be elusive and difficult to treat. In some cases, tendons or ligaments can rub over the edges of prominent implants, and revision surgery is required to remove the source of the impingement.
Patellofemoral replacement, or kneecap replacement, is also a partial knee replacement procedure. While uncommon, it is useful to treat patients with isolated kneecap arthritis. The benefits to partial knee replacement are the same:
The resurfacing of the kneecap is the same as total knee replacement: a plastic button is cemented to the back side of the kneecap (patella). A metal tray is placed in the trochlea, which is where the kneecap glides as the knee bends. The remaining portions of the knee are left untouched. This type of replacement can also be easily converted to a total knee replacement, if necessary.
Partial knee replacement is similar to a total knee replacement in that it is a resurfacing procedure. However, partial knee replacement refers to resurfacing of just one of the compartments of the knee. In other words, the inside, outside, or the kneecap area can be treated independently from the others. This option is appropriate for patients who have pain and arthritis isolated to a single portion of the knee.
Patients must be promptly identified with isolated or early arthritis to benefit most from this procedure. While total knee replacement is also a reliable option in these situations, partial knee replacement has the following potential benefits:
Studies have shown that partial knee replacement can be durable up to 15 years (and sometimes beyond) in certain, carefully screened patients. In addition, if arthritis develops elsewhere in the knee, a partial knee replacement can be converted to a primary, or first-time, total knee replacement.
Total (full) knee replacement refers to the resurfacing of all three compartments of the knee; the inside, the outside, and the kneecap portions of the joint. However, rather than “replacing” the entire knee, a total knee replacement refers to resurfacing the articulating surfaces of the knee joint.
A metal cap goes on the end of the thigh bone, recreating the anatomy of the end of the femur. A plastic liner makes up the other side of the articulating surface, and is fixed to a metal tray which is secured to the top of the shin bone.
Total Knee Replacement
This pamphlet describes knee replacement surgery in detail, including the potential risks and complications. It is required reading for my knee patients prior to surgery and has a section on minimally invasive knee replacement.
Hip replacement makes use of an artificial ball and socket to replace painful bone surfaces and restore smooth motion of the hip joint. The new socket fits into the pelvis tightly so that bone grows into the implant. A plastic liner locks into the socket as the bearing surface. Metal liners have been associated with early failures, so ceramic heads are currently favored over metallic ones in order to reduce the risk of corrosion developing at the taper joint.
The new ball is secured to a metal stem, which is fixed to the upper thigh bone. This component is either press-fit to allow bone growth fixation, or it is cemented into place. This determination is made based on the quality and shape of the bone, age of the patient, and other important factors.
Hip replacement is one of the most reliable orthopedic procedures available. Techniques have evolved in recent years to minimize patient pain, blood loss, and the length of hospital stays. Most patients are able to ambulate the day of surgery and regain independent function and activity quickly.
Total Hip Replacement
This helpful pamphlet describes hip replacement surgery in easy-to-understand terms, including the potential complications. It is required reading for our hip patients prior to surgery and has a section on minimally invasive hip surgery techniques.
Surgical Approaches to the Hip
This document reviews the pros and cons of anterior and posterior approaches to the hip joint during hip replacement surgery and answers questions raised by patients about the anterior approach, as well as the two-incision technique.
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Hip replacement is an artificial ball and socket which replaces the painful bone surfaces and restores smooth motion of the joint. The new socket fits into the pelvis tightly so that bone grows into the implant. A plastic liner locks into the socket as the bearing surface. Metal liners have been associated with early failures. Ceramic heads are currently favored over metallic ones in order to reduce the risk of corrosion developing at the taper joint.