David R.J. Gill
Pathogenesis
Etiology and Epidemiology
Rheumatoid arthritis (RA) is a chronic systemic inflammatory disorder in which the body's immune system mistakes articular cartilage for foreign (nonself) material. The exact cause for RA is unknown. Genetic susceptibility is recognized, including monozygotic HLA DR4, which has a 12% to 15% concordance rate. Women, especially postpartum and those breastfeeding, have an increased risk along with smokers.
In the United States approximately 2.1 million people are affected with rheumatoid arthritis, or approximately 1 per 300,000. It is generally believed that the ratio of women to men is between 2 to 1 and 3 to 1. It is rare in men younger than the age of 45 years; in this age group, the condition is predominately among women (6 to 1). The peak incidence is between the ages of 20 and 50 years, but it can affect both the young and the elderly. Its prevalence is lowered among black African and Chinese and among certain Indian tribes. It most commonly affects adults as a polyarticular disease where extra-articular features are uncommon.
Pathophysiology
The pathologic changes of RA can be separated into the following three phases:
Classification
The classification most commonly used is summarized in Table 59-1. This classification system is based on both the pathologic changes and the changing x-ray film appearances. This classification system can be used to guide the orthopaedist with regard to treatment options.
Diagnosis
The diagnosis of RA in general requires four of the seven revised American Rheumatism Association (ARA) criteria in the last 6 months.
When focusing on the elbow, it is important in the history to focus on pain, associated stiffness, and/or instability. One should inquire about neurologic symptoms, especially that of the ulnar nerve, remembering that approximately 40% of rheumatoid arthritic patients with elbow pathology have either clinical or subclinical peripheral neuropathy or nerve compressions. Previous surgery to the elbow (radial head excision or replacement and/or interposition) has prognostic implications. A more general view of the patient including the joints above and below the elbow and cervical spine in mode and abilities and ambulation is important. The overall functional capacity, e.g., the ARA classification, may also be useful.
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TABLE 59-1 Classification of Rheumatoid Arthritis of the Elbow |
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Examination
The aim here is to carefully consider the elbow and then the patient as a whole.
Radiologic Features
The general radiographic changes are summarized in Table 59-2; specifically, one should examine the plain x-ray films to determine surgical requirements. Canal capacity length and alignment relative to the articulate surfaces are important. Any bone thinning, particularly cortical bone thinning, especially at points of entry of the prosthesis or at the tips of potential prosthetic replacement, needs to be noted (Fig. 59-1).
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TABLE 59-2 Severity of Rheumatoid Arthritis Of the Elbow |
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Figure 59-1 Diagnostic workup algorithm. |
Treatment
Surgical Indications/Contraindications
The primary surgical indication is pain; the specific surgical goal is the relief of pain. Total elbow arthroplasty for rheumatoid arthritis should be considered in patients with grade 3 or 4 disease. The contraindications are bone or joint infection or an open wound about the elbow. Relative contraindications include the medical state of the patient specifically with regard to Parkinsonian or other neurologic disorders, particularly if the patient has a history of recurrent falls. The possibility that anaesthesia will place the patient at unnecessary risk must also be considered. The other relative risk is bone ankyloses. The technical demands of joint replacement at the elbow are such that the general orthopaedist should refer to those surgeons with high-volume experience in total elbow arthroplasty.
Surgical options relate to prosthetic choice. Both unconstrained and semiconstrained joint replacements are currently available. Traditionally, unconstrained joint replacement (with which there is no direct linkage between the humeral and ulnar components) has been considered for those patients with grade 3 disease where there is still primary ligamentous stability. Semiconstrained implants have a loose linkage between the humeral and ulnar components, allowing approximately 7 to 10 degrees of toggle at the articulation but at the same time maintaining the articulation's
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stability. This type of prosthesis is the most commonly used and may be considered for both grade 3 and grade 4 patients.
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Figure 59-2 Anteroposterior radiograph of an elbow with rheumatoid arthritis. |
Preoperative planning starts from the time of the history and examination, the orthopaedist having satisfied himself or herself that the patient is a surgical candidate and has no contraindications. The examination can specifically review those aspects important for the joint replacement itself—soft tissue coverage and the quality of the integument: There must be at least one flexor of antigravity power and preferably an extensor of similar power both for extension and to cover the prosthesis. Bone deficiency is covered both clinically and on the radiographs; the minimum requirement for a semiconstrained prosthesis is two tubes of bone (the humeral canal, the ulnar canal, and a grade 4 flexor). These are the minimum requirements for undertaking elbow replacement arthroplasty.
Templating prior to surgery, preferably during the clinic appointment, focuses the orthopaedist on any technical difficulties of implantation of the preferred implant. The size, the position of the humeral and ulnar cuts, and the relationship of the intramedullary canals to the articular surface are brought to the orthopedist's attention. Also of note is the curvature of the humerus on lateral view and therefore its relationship to the prosthesis being used and the narrowing on lateral view of the ulna beyond to the olecranon with specific reference to the stem of the prosthesis to be used (Figs. 59-2 and 59-3).
The specific surgical technique used for elbow replacement arthroplasty is covered in other chapters. Important steps to be focused on include the following:
Complications
Approximately 10% of total elbow arthroplasty patients will experience some type of complication. Most of these are
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minor and permit easy recovery. Intraoperative bone fracture, either that of the condyles or perforation of the canals, can occur without careful preoperative planning. If there is canal perforation, more distant neurovascular structures such as the radial or median nerve are at risk. Early complications include wound-healing difficulties, bleeding, and joint stiffness. Temporary paresthesia, particularly of the ulnar nerve, is also recognized. Late complications that have been recognized and should be considered are loosening of the implant's bushing in those implants using bushings, triceps failure, and component fracture. Infection of total elbow arthroplasty in rheumatoid patients is said to be approximately 2%, which is slightly higher than that of standard lower extremity (hip and knee) joint replacement.
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Figure 59-3 Lateral radiograph of an elbow with rheumatoid arthritis. |
Results
The expected result for total elbow arthroplasty in patients with rheumatoid arthritis is a 100-degree arc motion generally from approximately 30 degrees of fixed flexion to 130 degrees of flexion. The patient should expect excellent relief of pain, which provides a high degree of satisfaction. When scored by a common elbow evaluation rating at 10 years, 85% of patients will have a good or excellent result. The survivor rate is approximately 92% at 10 years for this group of patients.
Postoperative Management
After surgery, the elbow is splinted straight with a commercial or plaster of Paris splint until the following day. This achieves a decrease in elbow joint volume and therefore reduces swelling. Thermal regulation that caused the joint may also be used to reduce the initial swelling. Typically, once the dressings are removed, simple dressings are applied to the wound, a compressive long arm stocking is applied, and unrestricted elbow motion can be commenced. Discharge of the patient from the hospital is dependent on overall recovery as semiconstrained implants are stable from the beginning and no specific postoperative splinting is required. If an unconstrained implant is chosen, the manufacturer's specific recommendations must be followed regarding postoperative splinting and protection.
Total elbow arthroplasty in patients with rheumatoid arthritis requires specific restrictions in use of the limb and can be summarized as follows: no more than 5 kg repeated lifting and no more than 10 kg in a single event.
Suggested Readings
Gill DRJ, Morrey BF. The Coonrad-Morrey total elbow arthroplasty in patients who have rheumatoid arthritis. A ten to fifteen-year follow-up study. J Bone Joint Surg Am. 1998;80:1327.
Gschwend N, Scheier NH, Baehler AR. Long-term results of the GSBIII elbow arthroplasty. J Bone Joint Surg Br. 1999;81:1005.
Hildebrand KA, Patterson SD, Regan WD, et al. The functional outcome of semiconstrained total elbow arthroplasty. J Bone Joint Surg Am. 2000;82:1379.
Morrey BF. The Elbow and Its Disorders. 3rd ed. WB Saunders; 2000.
Potter D, Claydon P, Stanley D. Total elbow replacement using the Kudo prosthesis. Clinical and radiological review with five- to seven-year follow-up. J Bone Joint Surg Br. 2003;85:354.
Sanchez-Sotelo J, O'Driscoll S, Morrey BF. Periprosthetic humeral fractures after total elbow arthroplasty: treatment with implant revision and strut allograft augmentation. J Bone Joint Surg Am. 2002;84:1642.
Van der Lugt JC, Geskus RB, Rozing PM. Primary Souter-Strathclyde total elbow prosthesis and rheumatoid arthritis. J Bone Joint Surg Am. 2004;86A:465.