Elbow Joint Replacements: Can They Be Trusted?
Hip and knee replacements are so common now, no one questions them. But elbow joint replacement is a newcomer on the scene. There are still many questions left unanswered. Who should have one put in? When? How well do they work? Do they hold up over time?
Studies reporting results are slowly being published. In this report, Dr. J. D. Keener from Washington University in St. Louis summarizes what we know about total elbow arthroplasty or TEA as it is referred to in its shortened form.
There is more than one kind of artificial elbow joint (also called a prosthesis or implant). The most common types are like a hinge. Each prosthesis has two parts. The humeral component replaces the lower end of the humerus in the upper arm. The humeral component has a long stem that anchors it into the hollow center of the humerus. The ulnar component replaces the upper end of the ulna in the lower arm. The ulnar component has a shorter metal stem that anchors it into the hollow center of the ulna.
The hinge between the two components is made of metal and plastic. The plastic part of the hinge is tough and slick. It allows the two pieces of the new joint to glide easily against each other as you move your elbow. The hinge allows the elbow to bend and straighten smoothly.
So far, it looks like people of all ages with inflammatory arthritis like rheumatoid arthritis (RA) have the best results with elbow joint replacements. The implant holds up well over time. Elbow function is improved and patients are satisfied with the results.
But younger patients who either have osteoarthritis, arthritis from an injury, or a severe acute injury of the elbow seem to have a high rate of complications. This group is also more likely to need a second (revision) surgery.
Researchers are trying to get to the bottom of this problem. They are looking at all patient, implant, and surgical factors. For example, is younger age (with a higher activity level) the reason why TEAs come loose? Is there a specific feature (flaw?) in the implants that just doesn't work well with joint damage from trauma or the degenerative effects of osteoarthritis?
Trying to sort out effects of the implant itself has been a challenge. These prosthetic devices come in a wide assortment. They can be linked, unlinked, convertible from linked to unlinked, constrained, unconstrained, semi-constrained, cemented or uncemented, and so on. Each one of these design features addresses a specific problem such as torn ligaments or other soft tissue damage, bone loss, and elbow deformities.
What about complications? How do these compare between patients with rheumatoid arthritis versus osteoarthritis? In general, patients with rheumatoid arthritis (RA) have other health issues that result in complications. That's because RA is a systemic disease, not just a joint problem. Systemic means the disease affects many other systems in the body including heart, kidney, and lungs.
Comparing joint infections, poor or delayed wound healing, and the death rate, reported outcomes are fairly equal between the two groups. Older patients who fall and fracture the humeral part of the elbow are at greatest risk for death from pulmonary embolism (PE). Pulmonary embolism is a blood clot to the lungs. This complication doesn't have anything to do with which implant is used -- it's more of a patient factor.
As far as which TEA are the most durable (last the longest and have fewer mechanical problems), there is a national registry with data to help take a look back at success versus failure rates. Another word for durability of these implants is survivorship. Survivorship data comes from patients treated at many different clinics and hospitals.
The National Registry Data shows a fairly consistent 15 per cent failure rate. As mentioned, results are better in patients with rheumatoid arthritis. And there is a higher rate of revision surgeries when the implant was done outside of a joint replacement specialty hospital or center.
Loosening of the implant without infection (called aseptic loosening) is the number one complication across the board. But there have been other problems reported that require a second surgery (e.g., implant breaks, bushings wear out, mechanical failure of linkage pins.
With a large number of revision surgeries, surgeons also collect data on outcomes following those procedures. Surgeons face many additional challenges in revision TEAs. Once the first implant is removed, there may not be enough bone to anchor the second one. Damage to the soft tissues or nerves can also present some interesting problems. Deep infections in the first implant may be hard to get rid of and cause failure of the second implant.
In conclusion, there's more unknown than known about outcomes with total elbow arthroplasty (TEA). Much more study is needed to provide surgeons with evidence-based guidelines.
Patient selection, implant design, and reasons for failure are all areas of interest for surgeons providing elbow replacement for patients of all ages. Implant designs will continue to change and evolve requiring careful data collection to see what works and what doesn't.
References: Jay D. Keener, MD. Total Elbow Arthroplasty: What Are the Options? In Current Orthopaedic Practice. September/October 2010. Vol. 21. No. 5. Pp. 472-477.Back