Chapter 54 Prosthetic Joint Replacement
Manual of Rheumatology and Outpatient Orthopedic Disorders
Chapter 54 Prosthetic Joint Replacement
Harry E. Figgie, III
Definitions
Reconstructive alternatives
Indications for total joint replacement
Contraindications to total joint replacement
Expected benefits
Complications
Joint replacement in the lower extremity
Joint replacement in the upper extremity
I. Definitions
- Total joint arthroplasty consists of resecting a damaged joint and replacing the articulating surfaces with prosthetic components . The convex side is usually a titanium or chrome cobalt alloy that articulates with a concave surface made of high-density polyethylene. The polyethylene component is usually reinforced by a metal tray consisting of titanium or chrome cobalt alloy. Traditionally, polymethylmethacrylate bone cement has been used as a grout between the implant and the bone. This material provides fixation by filling the irregular interstices of the bone and closely contacting the prosthetic surfaces. Recent prosthetic designs and technology have allowed the prosthesis to be attached to the bone without cement . The efficacy and long- term durability of uncemented fixation in total joint replacement are not yet known.
- Resection arthroplasty consists of excision of the damaged joint for pain relief or control of infection. Stability and motion are achieved by the scar tissue that grows between the bone ends.
- Interposition arthroplasty consists of excision of the damaged joint and interposition of a biologic or foreign nonarticular material between two bones. Commonly interposed materials have included fascia, muscle, or silicone spacers. Relief of pain is the primary goal. Motion and stability are variable depending on the joint involved and the material used.
- Arthrodesis or fusion is obtained by denuding the articular cartilage and shaping the subchondral bone to maximize bone-to-bone contact. The process of fusion is similar to the healing of a fracture. When solid bony fusion is achieved, no motion is possible.
II. Reconstructive alternatives. The optimal artificial joint must allow for a stable, pain-free, functional arc of motion. Additionally, its expected longevity should be adequate with regard to material properties and security of fixation. In general, the performance of the more common types of joint replacement is superior to that of resection arthroplasty, interposition arthroplasty, or arthrodesis.
- Arthrodesis. In arthrodesis, the elimination of joint motion places abnormal stresses on the joint above and below the fusion and on the contralateral extremity. In addition, arthrodesis may be difficult to achieve when metaphyseal bone loss is present. Fusion is used predominantly as salvage for a failed arthroplasty of the knee and primarily in the ankle, wrist, and hip.
- Resection arthroplasty or intraposition arthroplasty has provided unpredictable pain relief, motion, and stability. It has been virtually abandoned in the knee and hip, except in salvage procedures, and is used most commonly in the wrist, carpometacarpal joint of the thumb, metacarpophalangeal joints of the hands, and metatarsophalangeal joints of the feet.
- Total joint replacement usually provides a stable, pain-free, functional arc of motion. Joint replacements of the hip and knee provide the most predictable results and have demonstrated adequate performance for more than 10 years . A small percentage of patients will require reoperation after 10 years, usually for loosening of prosthetic fixation.
III. Indications for total joint replacement are severe, unremitting pain with loss of joint function in the presence of radiographic evidence of articular damage. The degree of joint dysfunction is evaluated by using one of several quantitative scoring systems with numeric grades for preoperative pain, motion, stability, and activity levels. Postoperatively, the same system can be used to evaluate the degree and durability of improvement.
IV. Contraindications to total joint replacement
- Absolute contraindications. Active local or remote sepsis.
- Relative contraindications
- Neurologic disorders, including hemiparesis, parkinsonism, and Charcot's joint.
- Technical considerations
- Severe loss of bone stock.
- Poor soft-tissue coverage.
- Multiple revision procedures.
- Systemic illness precluding elective surgery.
- Nutritional factors.
V. Expected benefits
- Pain relief. Replacement arthroplasty has given excellent pain relief, and this is the primary indication for surgery in all joints.
- Motion. Range of motion following arthroplasty is closely related to the preoperative arc of motion.
- Stability is related to the joint being replaced , type of prosthesis used, amount of bone resected, and the degree to which periarticular ligaments are preserved and balanced.
VI. Complications
- Systemic complications include the risks of general or regional anesthesia, myocardial infarction, pneumonia, and urinary tract infection.
- Joint-specific complications
- Deep venous thrombosis. With regard to the hip and knee, the incidence of deep venous thrombosis may be as high as 60%. Pulmonary embolism occurs in 1% to 4% of cases and is the leading cause of mortality following elective total joint arthroplasty. Some form of anticoagulation is indicated in most patients undergoing total hip or total knee arthroplasty, but the type, duration, and time of initiation of the anticoagulation regimen remain controversial .
- Infection
- Acute infection results from bacterial inoculation of the wound at the time of surgery. This is treated with either open debridement, irrigation, and closure over drains or removal of the prosthesis followed by antibiotic administration in preparation for reimplantation. Appropriate parenteral antibiotic therapy depends on obtaining accurate culture and sensitivity reports and adequate blood levels of the antibiotic selected.
- Late infection that occurs 6 to 12 months postoperatively most likely arises from the hematogenous spread of bacteria from a site of active infection to the prosthesis. The most common sources of such a bacteremia are the genitourinary tract, colorectum, teeth, and skin. Late infection usually results in prosthetic removal and either immediate exchange with use of an antibiotic-impregnated cement or delayed exchange following parenteral antibiotic therapy.
VII. Joint replacement in the lower extremity. It is necessary to evaluate the status of all joints of a lower extremity when replacement of one of them is planned. Correcting one problem may create another (e.g., correcting a valgus knee may accentuate a fixed varus ankle deformity).
- Total hip replacement is the procedure with the most predictable and reliable results. A metal femoral component is anchored into the femoral canal with acrylic cement, and a polyethylene acetabular component is similarly fixed into the acetabulum. Newer techniques utilizing an uncemented prosthesis rely on tissue ingrowth into irregularities in the prosthetic surfaces for fixation. The efficacy of tissue ingrowth in preventing late loosening, which is the most common problem encountered with cemented implants, is not yet known.
- Total knee replacement utilizes polyethylene tibial and patellar components and metal femoral components that are either cemented or uncemented. Recent reports of long-term follow-up in cemented implants have shown knee replacement to be as predictable and reliable as total hip replacement, although technically more difficult. Close attention must be paid to alignment and ligamentous balancing during this procedure. Depending on the degree of deformity and ligamentous laxity or contracture, varying degrees of linkage between the tibial and femoral components may be selected in different prosthetic systems. In general, a completely constrained hinged implant will create high torsional stresses at the interface between prosthesis and bone and, therefore, will have unacceptably high rates of loosening or failure of prosthetic material. In most cases, less constrained systems are used that depend on either ligaments or augmented prosthetic surfaces for stability.
- Total ankle replacement has a limited application. It is useful in a patient with severe arthritis of both ankles and subtalar joints, when an ankle fusion would be severely disabling. Ankle replacement usually provides an arc of motion at the ankle that allows a more physiologic gait cycle than would a fusion.
Because of the high loads that cross the relatively thin components and cement, loosening may be a problem. This technically difficult procedure is reserved primarily for less active patients with polyarticular arthritis.
VIII. Joint replacement in the upper extremity. Planning any joint replacement in an upper extremity must be directed at relieving pain and providing a functional hand. When several joints in the upper extremity are involved, the wrist and hand should receive primary attention, unless severe pain demands the replacement of a more proximal joint first.
- Total wrist replacement usually provides a functional range of motion in addition to pain relief. It is therefore superior to arthrodesis from a functional standpoint, but its long-term efficacy has not been proved. The high loads that cross the small prosthesis are capable of causing loosening in the cemented replacements or excessive wear debris and secondary synovitis in silicone interposition arthroplasty. If a patient is active and expects to perform significant manual labor, an arthrodesis is the treatment of choice.
- Finger implant arthroplasty. Silicone interposition arthroplasty has been used successfully at the metacarpophalangeal joints in arthritic patients.
Pain relief, functional motion, and good stability may be obtained routinely provided the preoperative deformity is not too great and that functioning muscle-tendon units are still operative . Recent advances in cemented arthroplasty of small joints have made possible the replacement of proximal interphalangeal joints, but the surgical results have not been evaluated during a long-enough period to demonstrate a clear and long- lasting advantage over arthrodesis.
- Total elbow replacement. The elbow is an especially complex joint because of its crucial role in moving the hand in space throughout a wide range and the requirements for stability that are placed on it. Loads of up to six times one's body weight cross the elbow during the activities of daily living. An arthritic elbow can be severely painful and stiff and, in some cases, unstable. This presents significant disability to a patient with polyarticular rheumatoid arthritis who uses a cane or crutches. Replacement of the elbow joint is a technically demanding procedure that may produce significant, long-lasting relief of pain in a relatively inactive patient. The linked prostheses have built-in stability against varus-valgus stress and can be used in severe joint deformity. Minimally constrained surface replacements require the integrity of ligamentous structures around the elbow for success.
- Total shoulder replacement. The replacement of the humeral head with a stemmed metallic prosthesis and the glenoid with a polyethylene component provides the arthritic patient with relief of pain and, in many cases, restores a functional range of glenohumeral motion. Postoperative range of motion is largely determined by the preoperative condition of the rotator cuff. Therefore, rheumatoid patients with atrophic cuffs are less likely to gain significant motion than are patients with posttraumatic arthritis or avascular necrosis of the humeral head.
Books@Ovid
Copyright 2000 by Lippincott Williams & Wilkins
Stephen A. Paget, M.D., Allan Gibofsky, M.D., J.D. and John F. Beary, III, M.D.
Manual of Rheumatology and Outpatient Orthopedic Disorders
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