Posted by: wockhardthospitals | July 23, 2009

Evolution Of Joint Replacement

With the Present life style, there is an increase in various health problems, which in turn leads to the invention of better health-care facilities. One such area that is evolving in the Indian health-care is Joint Replacements.

Joint replacement becomes essential whenever the natural joint is damaged affecting the normal body function, the main reasons being arthritis, joint infection, injury and malignancy. Prosthesis is an artificial joint that is used to replace a worn out or destroyed joint during joint replacement surgery, primarily used to relieve pain of an arthritic joint. Additionally, they provide stability, range of motion and restoration of joint function.

Statistics bear testimony to the growing significance as in India alone around 150 million people are suffering from the crippling disease of arthritis, which is around 15 per cent of the total population. On an average, one million people in India need total joint replacement, but only 30,000 to 40,000 joints are replaced yearly. The market for joint replacements is worth around Rs. 200 crore. There is a whole range of prostheses available for conditions ranging from degenerative arthritis, rheumatoid arthritis, previous failed surgery, bone and joint tumors, and unstable painful joints where supporting ligaments have been damaged. For a total hip replacement, the prostheses available are cemented, uncemented or hybrid. For a total knee replacement, they are usually cemented but have a fixed or rotating platform.

A Serious Need

All joint replacements involve prosthesis placement. Joint replacement prostheses are available for knee, hip, shoulder and elbow joints in the human body. “Among the joints needing replacement in the Indian population, the most frequent is the knee followed by the hip and occasionally the shoulder, The knee is most commonly replaced, with 2,50,000 people undergoing surgery every year in the world and 25,000 in India with numbers growing every year.

THE PROCEDUREThe procedure is performed in an operating room after the patient receives general, spinal, or epidural anesthesia. With general anesthesia, the patient is given medications through an intravenous injection and inhaled gas to induce sleep. The patient is unable to move or feel anything during the operation and will not remember the procedure afterwards.

Spinal and epidural anesthesia are forms of regional anesthesia in which an injection of anesthetic in the lower back temporarily blocks the feeling in the lower part of the body. With spinal anesthesia, the anesthetic is injected directly into the cerebrospinal fluid (CSF) surrounding the spinal cord; with epidural anesthesia, it is injected into the epidural space below the level of the spinal cord. The type of anesthesia used will depend on the particular patient’s situation and is determined by the health-care provider.

TKR: The patient is given antibiotics to reduce the risk of developing an infection. An incision is made to expose the inside of the knee joint. The bone and cartilage on the lower end of the femur (thigh bone) and upper end of the tibia (shin bone) are removed. The replacement (prosthetic) joint, usually made of metal and plastic, is then implanted.

In THR, the head of the femur (the bone that extends from the hip to the knee) is removed along with the surface layer of the socket in the pelvis (the two large bones that rest on the lower limbs and support the spinal column). The head of the femur, which is situated within the pelvis socket, is replaced with a metal ball and stem. This stem fits into the shaft of the femur. The socket is replaced with a plastic or a metal and plastic cup.

The exact type of implant and the method and location of the incisions depend upon the needs of the particular patient and the surgeon performing the procedure. All total knee arthroplasties consist of a femoral component, a tibial component and a patellar component. There are many manufacturers and designs of knee prostheses. Most prostheses last at least 10 years; the prosthetic joint lasts longer in older, less active patients, and in patients with rheumatoid arthritis (as opposed to osteoarthritis).

After implantation, x-rays of the new prosthetic knee are taken. This allows the surgeon to confirm and document the correct placement of the joint

Management — Postoperative management includes controlling pain with intravenous or oral medication. Many joint replacement patients are given “patient-controlled analgesia”. This gives pain medication through an intravenous line (IV) in the hand or arm. Patients are able to control, within preset limits, when a dose is given. Patients are also given an antibiotic (generally for 24 hours following surgery).

A blood-thinning medication such as low molecular weight heparin (Lovenox® or Fragmin®) or warfarin will be given to help prevent blood clots in the legs. Compression boots (devices that go around the legs and inflate periodically) or special support stockings are often used to aid in the prevention of blood clots. The support stockings are usually worn for several weeks following surgery.

Patients are encouraged to start moving the feet and ankles immediately after surgery. Some surgeons also recommend the use of a continuous passive motion (CPM) device, which elevates and slowly moves the leg while the patient is in bed. It is common to begin physical therapy, including exercise of the knee and trying to walk, as soon as one day after the procedure.

Cemented hip replacement can cost between Rs 35,000 and Rs 40,000, whereas the price of an uncemented one could range between Rs 60,000 and Rs 1.5 lakh. The difference in the cost structure is because the materials used for uncemented hip prostheses are more expensive and also they are technically more challenging to manufacture. The standard cemented knee prostheses available today in the market costs around Rs 75,000, whereas the mobile bearing one which lasts longer due to decreased wear, costs Rs 10,000 to Rs 15,000 more than the fixed bearing

Chronological Overview

Modern day joint replacement began in the early 1960s, when Sir Charnley introduced cemented metal-poly ethylene components for hips and in the late 1960s Gunston transferred the same technology to the knee. The principles proposed by Charnley were rigid fixation of the components to the bone, resurfacing of both joint surfaces and use of materials with low friction and wear. These principles, embodied in cemented metal on plastic components, have stood the test of time to this day. In 1970s, and 1980s many hip designs were introduced based on Charnley’s design.

Most of the designs in use today, uni-compartments, condylar replacement with or without cruciate retention, mobile bearing knees, stabilised condylars, fixed and rotating hinges were all introduced before the early 1990s. Ceramic on polyethylene and ceramic on ceramic were also introduced at the same time.

Early 1990 saw two important areas of development – more sophisticated instrumentation especially for the knee and uncemented components with porous coatings for indefinite fixation. The situation today is that many designs of hips and knees have shown survival of greater than 90 per cent in 10 years. Today, hip and knee systems offer a large variety of sizes and modularity suitable for all.

Change in the Constitution

Gradual change of implant material from stainless steel to an alloy and high-density polyethylene has resulted in increased implant life with minimal wear. “Today, the life of prosthesis is more because of new technology used for its design and introduction of computer-assisted joint replacement surgery

Most prostheses today consist of a metal capping one end of the joint and a softer plastic poly capping the other end. However, there is a resurgence of smooth, highly polished metal surface used on both sides of hip replacement after three decades.

Hybrid surface products like the Oxynium combine the hardness of metal without the problem of metal ion release and smoothness of ceramic without the brittleness of ceramic. The outer surface of uncemented implants is designed to favour biologic bone in-growth and fixation of the prosthesis. This can be in the form of rough beads, wire-mesh or other rough porous surface of titanium, which is an osteophilic material. Hydroxyapatite coating is often used to induce bone in-growth on to the prosthetic surface. The various prostheses available in Indian market are from Depuy, Zimmer, Stryker and Aesculap. Common cemented hip prostheses available are Charnley’s, Exeter, C Sten prosthesis, while non-cemented prostheses available are AML, Pinnacle, Zymuller, Corail and Proxima.

Types of Prostheses

The different kinds of prostheses used vary with the joint that is being replaced.

Total Hip Replacement (THR) prostheses: They are generally classified as cemented or uncemented (cementless). Cemented THR is indicated in the elderly age group of patients (65 years and above), while uncemented THR is the prosthesis of choice in the younger patient.

Bipolar hip replacement: A type of prosthesis where the femoral component is fixed into bone, but the acetabular component (cup) is not fixed in the acetabulum thus allowing the cup to move freely in the socket. This type of prosthesis is more commonly used in patients with fractures of the neck of femur (transcervical fractures).

Total knee replacement (TKR) prostheses: They are classified as fixed bearing (conventional) and mobile bearing (like the rotating platform knee). These prostheses are usually fixed using bone cement.

Selection of Prosthesis

The selection of a prosthesis depends on the patients’ age, activity level, and the primary pathology involving the joint. A cemented THR is the prosthesis of choice in the older and low demand patient, as opposed to an uncemented prosthesis in the younger and active patient.

“The rationale behind using an uncemented THR in the younger patient is that these patients are likely to outlive their prosthesis (average life of a prosthesis is about 15-20 years), and an uncemented prosthesis is expected to leave behind a better bone stock (quality) at the time of revision surgery than a cemented THR,

A bipolar hip replacement is indicated for an elderly patient with a transcervical (neck) fracture of the hip. With regard to TKR, a fixed bearing (conventional) prosthesis is preferred in the elderly patient while a mobile bearing TKR may be indicated in the young active patient with knee arthritis

Issues and Concerns

The primary areas of concern in joint replacement surgeries are infection (one-two per cent) and loosening of the implant, dislocation (one-two per cent), fractures and implant failure. “The infection risk can be minimised by the use of ultra modern operating theatres (clean air theatres), body exhaust suits (space suits), appropriate prophylactic antibiotics, and strict adherence to principles of asepsis by all the theater personnel,

Future of joint replacement

Some latest advancement in joint replacement surgery is the use of computer navigation during surgery and minimally-invasive surgery where the size of incision is half the size of conventional incision, which is more cosmetic. Some new hip prostheses are surface hip replacement prosthesis where the bone cut is less, hence the original bone is saved as only the surface is replaced and head and neck of the joint are largely saved, and large head metal on metal hip replacement prostheses which offer the advantage of large ball and are more stable so dislocation rate is low. Here are some of the latest prostheses:

Hi-flex knee

The newer prostheses designs are targeted towards achieving higher flexion-bending and a new era of joint replacement surgery using hi-flex knee designs. “The hi-flexion knee prosthesis allows the patient to bend their knee as much as a normal knee allowing more mobility and flexibility in the joint,

Computer Navigation System for joint replacement provides more accurate implantation by digital mapping based on standard anatomical landmarks and kinematic Analysis. It guides the surgeon in all the steps of surgery and even point out errors before they are made. The computer navigates the path of instruments in such a way that an implant is fitted in the most optimum position. It also helps in adjusting the ligament tension that is very vital to get a stable joint with good range of motion. It includes a computer console, touch screen monitor and couple of infrared cameras that track the position of the leg and the components. The accuracy of the steps is improved to 0.5 degree and to one millimeter .apart from improving the precision of bone cuts, the computer also helps in restoring the soft tissue balancing that is critical in getting the desired good results

The Advantages of Computer Guided Joint Replacement Surgery

  • Restore accurate leg alignment

  • Increase the survival of the implanted joint

  • Reduce the risk of complication due to improper implantation

  • No radiation during surgery

  • Constant guidance & monitoring during surgery

  • Range of motion analysis to achieve maximum function

  • Minimally invasive surgery hence decreased blood loss

  • Decreased hospital stay

A minimally invasive knee replacement or less invasive knee replacement is carried out through a smaller incision and produces less amount of pain. In this procedure the same prosthesis is implanted using smaller incisions and specially designed instrumentation. Duration of hospitalization will be lesser, there is no need of transfusions, pain is lesser and the cosmetic effect is better. Rehabilitation will also occur faster, a return to normal activity may be possible in 4 weeks.

Pulsatile Lavage System: Pulsatile Lavage System that is used to lavage the cut bone ends during joint replacement and for the irrigation of open fractures

Benefits

  • It provides better fixation of implants.

  • Reduces infection in joint replacement

  • No debris or loose bodies in the joint during joint replacement surgeries

  • In open fractures it helps to remove sand, paint or grease from the wound and reduces the rate of infection.

Laminar Airflow filtering system / Vertical layer of Sterile:

Air flows from the roof, to surgical field and then sucked into the filtering system by the ducts in the walls. This system of air delivery has additionally reduced the infection rate in patients who have a total joint replacement

Helmets and sterile suits: To further reduce the rate of infection

Gender-specific knee implants

Gender-specific knee implants are being devised for women as these are more suited to their anatomy. “Gender-specific knee is lighter, better shaped to fit, has got a better tracking for the knee cap (patella) and allows the full flexion,

Surface hip replacement

A newer prosthesis with an aim to preserve bone and allow a better range of movement referred to as hip resurfacing prosthesis has been in use for the last five years with good early results in the selected patient. Very few Indian patients are suitable for this procedure as the primary pathology in India is HIP AVN leading to arthritis, rather than primary hip arthritis seen in the Western world. “The same benefits of resurfacing without the risks are possible with a metal on metal large head hip prosthesis now available. Proxima hip is the latest implant available that offers full function to the patient with minimal bone loss. The newer knee prostheses have no change in material except the shape which is designed to give better movement while bending the knee and allow the patient to squat and sit cross-legged.

Uni-Compartmental Knee Replacement

Unicondylar knee replacement either of one or both condyle opens up the possibilities of minimally invasive surgery. This has been designed to replace only part of the arthritic knee which is significantly damaged. “The results are encouraging but only of use in patients who come early before their entire knee is damaged,”

Pain Management

For more than three decades, hip and knee arthritis has been treated with joint replacement surgery. These surgical procedures reliably relieve joint pain and stiffness for many years after surgery.

However, hip and knee replacement are major surgeries and there is considerable pain at the surgical site. Over the years, surgeons have treated the pain with narcotics and epidural (spinal) medications. Overall, pain control was acceptable, but significant pain and side effects of the pain medications continued to slow the early recovery from surgery. Recently, new strategies for post operative pain management have been developed to provide better pain control and facilitate faster recovery.

A new pain management program called Rapid Recovery is a combination of medicines used before, during and after surgery to minimize pain and maximize a patient’s ability to resume movement following surgery. Joint replacement patients treated with the Rapid Recovery program have had decreased pain, decreased nausea, accelerated postoperative rehabilitation and overall higher patient satisfaction.

The Rapid Recovery program uses three stages to control pain.

The first stage begins before the operation. Before entering the operating room, the patient receives medications. Each medication treats a different pain pathway. Medications are given before surgery so they are already working when the patient awakens in the recovery room.

The second stage takes place at the time of surgery. During the operation, the surgeon injects a long acting local anesthetic and an anti-inflammatory into the tissues surrounding the hip or knee. Once again, this treatment is working by the time the patient is in the recovery room.

The final stage begins immediately after surgery and continues throughout the hospital stay. The post operative stage includes scheduled pain medications that also work on different pain pathways and minimize the use of narcotics. The combined medications addresses pain before it starts, allowing lower doses and minimizes the side effects such as nausea and fatigue.

The overall benefits of total joint surgery with the Rapid Recovery program include:

  • “Next Generation,” advanced pain management.

  • Early ambulation, with progressive rehabilitation.

  • Comprehensive pre-operative education program.

  • Potential for discharge on post-operative day two to three.

  • Potential for discharge to home from the hospital.

  • Long term follow-up.

Anesthesia

Alternative modes of anesthesia & analgesia – Many anesthetists and surgeons prefer regional and local modes of abolishing operative pain. Spinal, Epidural and local nerve blocks may be administered by skilled anesthetists. The benefits are increased safety as there is less stress upon the body. Diabetics, Hypertensive, and people with ischemic heart disease can undergo safe surgery. As the patient is not unconscious and is only sedated, he is unlikely to feel postoperative nausea and vomiting. A drink or light meal can be given soon after surgery as tolerated and this comes as a big boon to many elderly who are unable to tolerate overnight starvation and thirst. Multi modal post operative pain relief – Instead of relying on opioids, multimodal analgesia employs a battery of pain relief methods and drugs. Pain relief is near total and the patient will not regret the surgery experience at all. Cryotherapy oral drugs, pain pumps, epidural anesthesia are all used to make your experience as pleasant as possible

RehabilitationPhysical therapy is an important part of the recovery process. Most patients spend three to five days in the hospital, during which they work with a physical therapist to develop an exercise and rehabilitation program. Some patients continue their therapy at home under the supervision of a physical therapist, while others may stay in a rehabilitation facility until they are able to perform daily activities independently.

The rehabilitation program generally includes: exercises to improve range of motion, gait training, thigh muscle (quadriceps) strengthening, and training in activities of daily life. The patient’s goals and expectations are based on evaluation by and discussion with the physician and physical therapists.

Patients can usually resume their normal activities within three to six weeks following knee replacement. The goal of the rehabilitation period is regaining strength and motion; it is important to avoid overworking or straining the knee during this recovery period. After several months of rehabilitation, patients are encouraged to maintain an active lifestyle. While high-impact sports such as running or contact sports should be avoided, patients can typically participate in activities like walking, cycling, and swimming.

Let us look at some of the recent advances in total knee replacement available in India.

1) Minimally invasive surgery – If you ask your friend who has undergone a knee replacement, about the worst thing about the surgery, he or she is likely to blame the amount of post operative pain. Some amount of Post op pain is inevitable from any operation. The amount of tissue dissection in normal knee replacements causes iatrogenic damage to the lining of the joint and results in pain postoperatively. A minimally invasive knee replacement or less invasive knee replacement is carried out through a smaller incision and produces less amount of pain. In this procedure the same prosthesis is implanted using smaller incisions and specially designed instrumentation. Duration of hospitalization will be lesser, there is no need of transfusions, pain is lesser and the cosmetic effect is better. Rehabilitation will also occur faster, a return to normal activity may be possible in 6 weeks.

2) Alternative modes of anesthesia & analgesia – Many anesthetists and surgeons prefer regional and local modes of abolishing operative pain. Spinal, Epidural and local nerve blocks may be administered by skilled anesthetists. The benefits are increased safety as there is less stress upon the body. Diabetics, Hypertensive, and people with ischemic heart disease can undergo safe surgery. As the patient is not unconscious and is only sedated, he is unlikely to feel postoperative nausea and vomiting. A drink or light meal can be given soon after surgery as tolerated and this comes as a big boon to many elderly who are unable to tolerate overnight starvation and thirst. Multi modal post operative pain relief – Instead of relying on opioids, multimodal analgesia employs a battery of pain relief methods and drugs. Pain relief is near total and the patient will not regret the surgery experience at all. Cryotherapy oral drugs, pain pumps, epidural anesthesia are all used to make your experience as pleasant as possible

4) High flexion knee prosthesis – Religious customs of Islam dictate kneeling five times a day for prayers. Westerners also demand more flexibility from their artificial knees and are intolerant of first generation implants which allowed the patient only to sit in a chair. Westerners like to pursue hobbies like gardening and demand flexi knees. Sex is made easier by flexible knee replacements. These special knee implants provide more flexion or bending. This suits Indian, South Asian habits of kneeling for prayer and sitting cross legged. The design features of such knees incorporate cut outs at the front, rotating platform or mobile bearings, increased bony resection at the back amongst others.

5) Navigational surgery -Navigational surgery or computer assisted enhances the accuracy of the operation. With the computer to guide, surgeons can make bony cuts with more precision and place the right size of implants. Not only this, computer assisted surgery (CAS) allows the operation to be performed by minimally invasive surgery (MIS). Perfectly positioned implants are less likely to loosen over time, decreasing the revision rate and ensuring survivor ship of the implant.

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