CHAPTER SYNOPSIS:

Arthroscopic debridement, ulnohumeral arthroplasty, interpositional arthroplasty, and total elbow replacement are the mainstays of treatment for elbow arthritis. Several new techniques, such as gene therapy and modular total elbow replacement, are emerging, whereas others, such as cartilage regeneration procedures, have been used successfully in other joints and have demonstrated early successes in the treatment of elbow arthritis or its precursor lesions. The rationale behind the development of gene therapy and modular total elbow arthroplasty is presented with preliminary studies involving their use. The techniques of cartilage restoration and distraction arthroplasty are described along with current indications and early- and mid-term results.

IMPORTANT POINTS:

Gene Therapy

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  Investigators have successfully transferred gene sequences into recipient human subjects.

  
  
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  Several obstacles, such as prolonged transgenic expression and efficacy of transgene products to change the course of the disease, must be overcome before this technology can be implemented.

Cartilage Restoration

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  Of articular cartilage lesions treated nonoperatively, 50% cause pain and arthritis at 20 years.

  
  
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  Stable lesions in adolescents with open capitellar physes should be treated nonoperatively.

  
  
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  Unstable or lesions in patients who are skeletally mature are more amenable to surgical intervention.

  
  
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  Microfracture is preferred for smaller lesions (less than 50% of the articular surface), and mosaicplasty has been advocated for larger lesions.

Distraction Arthroplasty

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  Accurate placement of the transaxial pin is achieved by placing the pin in the center of the capitellum on lateral fluoroscopic projections and serially following the pin fluoroscopically across the distal humerus.

  
  
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  Meticulous pin care and careful dissection during pin insertion limit common complications, such as pin-tract infections and iatrogenic nerve injuries.

Modular Total Elbow Arthroplasty

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  Modular total elbow arthroplasty allows transition from unconstrained to semi-constrained prostheses without explanting the ulnar or humeral components.

  
  
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  High rates of early complications, including radial head dissociation and periprosthetic fractures, have tempered enthusiasm over early-generation implants.

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INTRODUCTION

Elbow arthritis remains a difficult dilemma for most orthopedic surgeons. Although significant improvements have been made since Dee introduced elbow replacement in 1972, major advances in the treatment of elbow arthritis have lagged behind those of other joints, such as the knee, hip, and shoulder. Most available methods, such as arthroscopic debridement, ulnohumeral arthroplasty, interpositional graft insertion, and elbow replacement, are successful over short- and mid-term followup but lead to less favorable long-term outcomes. Furthermore, interpositional and total elbow arthroplasty, the options available to surgically treat moderate and severe arthritis, represent significant surgical undertakings with the potential for premature or catastrophic failure, or both. Adverse outcomes occur more frequently in high-demand patients, who, not coincidentally, are also the group most likely to develop elbow osteoarthritis or posttraumatic arthritis.

Because of the gaps between patient needs and available options, elbow arthritis is ripe for the development of new technologies. Advances produced over the past decade fall under one of three general categories: (1) prevention of the disease, (2) improvement of previous techniques, and (3) introduction of new treatment strategies. Although research into the use of gene therapy to treat rheumatoid and osteoarthritis remains preliminary, several methods have shown mid-term success in delaying the onset of osteoarthritis in young patients sustaining osteochondral defects. Two treatments for advanced arthritis—distraction arthroplasty and modular total elbow arthroplasty—have been used intermittently, but long-term followup studies remain scarce.

GENE THERAPY

Ideally, all forms of arthritis could be treated in its early stages by local injection of materials to halt or reverse the cartilage destruction. Vigorous research is currently being conducted to develop a system to replace or overpower deleterious genes or their proteins. Although research is still in its infancy, evidence is accumulating that gene therapy may become a tangible option in the orthopedist’s armamentarium of the future.

Before gene therapy becomes reality, several prerequisites must be accomplished. First, genes and their products must be identified and their functions must be elucidated. Second, a vector, usually viral or plasmid DNA, must be capable of transferring the desired genetic DNA into the target cell. Third, the “transgene,” or newly transduced genetic sequence, must retain the ability to express the desired product within the new host. Fourth, the transgene and its product must escape the clenches of the human immune system and remain viable long enough to elicit the desired response, which varies according to disease. For example, episodic conditions such as rheumatoid arthritis may require sustained activity of the transgene and its product, whereas limited expression for a finite period may be adequate to elicit the desired outcome. Finally, the transgene and its vector must be safe to the implanted host. Although the implanted viruses are altered and theoretically nonvirulent, there have been scattered reports of adverse effects and even several deaths attributed to gene transfer.

Although the roles of various genes and cytokines involved in rheumatoid and osteoarthritis have been and continue to be elucidated, a major advancement in gene therapy has been the ability to transduce cells with a gene encoding an interleukin-1 (IL-1) receptor antagonist, which reduces disease in animal models of rheumatoid arthritis. Investigators have successfully transferred the IL-1 receptor antagonist gene into the metacarpophalangeal joints of nine women with rheumatoid arthritis. One week following injection of the vector, each patient underwent planned Silastic replacement of the joint; the synovia recovered from all nine subjects demonstrated elevated amounts of the IL-1 receptor antagonist. Although successful gene therapy is far from widespread use, critical early stages of development have successfully been undertaken.

MICROFRACTURE AND MOSAICPLASTY

Osteochondritis dessicans and osteochondral defects of the humeral capitellum are recognized precursor lesions leading to elbow osteoarthritis and, as the number of adolescent athletes increases, may contribute to an increased incidence of elbow osteoarthritis in the future. Reports suggest that, left untreated, adolescent capitellar osteochondritis desiccans progresses to degenerative joint disease in nearly 50% at an average of 23 years. Therefore, future efforts to restore articular cartilage may prevent or retard the development of elbow arthritis.

Several options exist to manage osteochondritis desiccans and osteochondral lesions of the capitellum. These strategies include traditional methods such as nonoperative elbow rest, arthroscopic debridement with excision of loose fragments, and microfracture and newer procedures such as osteochondral transplantation and autologous chondrocyte implantation.

Osteochondral transplantation, or mosaicplasty, involves the transfer of hyaline cartilage with its underlying subchondral bone into an area devoid of articular cartilage. Because of relatively low morbidity, the lateral trochlear ridge of the lateral femoral condyle is often selected as the donor site. Several commercial systems are available to facilitate the procedure.

Autologous chondrocyte implantation is a two-staged procedure in which cartilage cells are harvested from the patient, sent to a laboratory to be cultivated, and reimplanted into the defect beneath a periosteal flap. No series has been published that specifically addressed the use of autologous chondrocyte implantation in the elbow. In the United States, its only approved use remains the treatment of distal femoral lesions.