Ankle Fusion or Ankle Replacement! A Growing Sector in Orthopedics

Ankle fusion and total ankle replacement are both recognized procedures to treat degenerative ankle joints. Studies conducted by the AAOS (American Academy of Orthopaedic Surgeons) are encouraging for both treatments. Some studies suggest ankle fusion may be a better treatment as it has fewer complications than replacement. Others recommend ankle replacement. One thing most studies agree upon is that after fusion the patient loses some degree of motion, while replacement provides the optimal function. According to the PearlDiver database, ankle fusions, the more conservative treatment, are still more commonly performed in the U.S. than are total ankle replacements.

Most fusion procedures are done on an inpatient basis, while total ankle replacements are often done at an outpatient site. The following table shows the total number of patients treated on an inpatient basis and on an outpatient basis for either ankle fusion or total ankle replacement in our database.

Table 1: Ankle Fusion and Ankle Replacement by Site of Care

A study conducted by Dr. Nelson F. SooHoo of Los Angeles, California, and his colleagues suggests that ankle replacement has a higher risk of complications than fusion, but replacement also has the potential advantage of less risk if patients are undergoing subtalar joint fusion. (Paper No. 265, “Comparison of reoperation rates following ankle arthrodesis and total ankle arthroplasty,” AAOS 2008)

Another study, conducted by Dr. Alexej Barg and Dr. Beat Hintermann from Basel, Switzerland, recommends a conversion to total ankle replacement in case of failure of the ankle fusion. Their study was based on 30 cases in which a failed ankle fusion was converted into a total ankle arthroplasty. Their study concluded that patients regained most of their optimal ankle function along with pain relief. (Paper No. 266, “Take down of painful fusion and conversion into total ankle arthroplasty,” AAOS 2008)

Interview With Dr. Steven Neufeld

Dr. Steven K. Neufeld is a board certified, fellowship-trained orthopedic surgeon who specializes in the foot and ankle at The Orthopaedic Foot & Ankle Center of Washington, based in Arlington, Virginia. (http://www.footankledc.com).

Dr. Neufeld believes that many factors—age, obesity and joint infection, as well as skin or health problems—need to be considered in deciding which treatments are best for patients. According to him, patients older than 50 years generally get total ankle replacements. Ankle fusions are more often performed on younger patients whose bones can handle the level of stress. Dr. Neufeld reports that patients with obesity or skin-related infections generally undergo ankle fusions due to the risk of complications with total ankle replacements. Each treatment, he believes, has its own benefits and drawbacks, and thus its use depends on factors relating to the individual patient.

In his new study titled “Controversy of Total Ankle Arthroplasty” to be released later this year, Dr. Neufeld cites evidence showing that total ankle arthroplasty has been evolving steadily over the last few years and that good results have been reported in aging patients who are non-obese and in the end stages of osteoarthritis or rheumatoid arthritis. He notes that because the ankle joint is fragile, it presents a small area in which to work and has a limitation of bone strength that makes total ankle arthroplasty a challenging procedure.

Information From PearlDiver Database

One of the most common diagnoses associated with both of these procedures is osteoarthrosis. Osteoarthrosis unspecified with ankle and foot (ICD-9-D-715.97) and osteoarthrosis local with ankle and foot (ICD-9-D-715.37) account for 70% to 80% of the fusion and replacement procedures. Hypertension (ICD-9-D-401.9) is also one of the diagnoses associated with fusion or replacement. The PearlDiver database shows an average charge for ankle fusion of $30,532, while the average cost for a total ankle replacement was reported as $43,017.

The PearlDiver database shows patients undergoing ankle fusion at a far higher rate than patients undergoing total ankle replacement (see Chart 1 below). However, the database does not include patients 65 years and older, which may account for why fusion procedures appear to be so much more frequent than total replacements. Older patients tend to be treated with ankle replacement for better optimal function.

Chart 1: Ankle Fusion vs. Ankle Replacement

Source: PearlDiver Patient Records Database, 2004-June 2007

According to John T. Treace, Vice President of Biologics and Extremity Marketing at Wright Medical Technology, Inc., the company’s recent acquisition of INBONE Technologies, Inc. has given Wright strength in its quest to become the recognized leader in the foot and ankle market. INBONE Technologies is the maker of the INBONE™ Total Ankle System and the INBONE™ Intra-osseous Fusion Rod and Plate System.

Wright Medical Technology is one of the top three companies within the U.S. total ankle replacement segment. The other two are DePuy Orthopaedics with its AGILITY™ Total Ankle System and Tornier with its Salto Talaris™ Anatomic Ankle. Integra also has a total ankle replacement product named HINTEGRA® (Int'l). HINTEGRA is used only in the international market as it has not yet been approved by the FDA. Treace believes Wright Medical will emerge as one of the top five companies in the foot and ankle reconstructive market (along with Integra, Arthrex, Tornier, and DePuy) with its newly acquired fusion rod and plate system from INBONE as well as its own products, such as the DARCO® line of locked plating systems and its CHARLOTTE™ reconstructive systems.

Treace reports that total ankle replacement is more popular in Europe than it is in the United States, with about 75% of the ankle fusion candidates in Europe undergoing total ankle replacement compared to 10% in the United States. One reason for this is that comprehensive reimbursement coverage for total ankle replacement is not presently available in the U.S. Other limiters in the U.S. include lack of availability of next-generation ankle replacement and controlled studies demonstrating superior outcomes versus ankle fusion. According to Treace, the market "opportunity" for total ankles in the U.S. is estimated to be around $250 million, but current U.S. revenue from total ankles (for all manufacturers) is <$20 million. He also mentioned that he estimates about 2,000 patients undergo total ankle replacement compared to 18,000 patients who receive ankle fusions in the United States.

Both the total ankle replacement and ankle fusion markets have good growth opportunity within the United States and abroad, according to Treace. He estimates that five years from now up to 50% of fusion candidates may be receiving total ankles. Once the reimbursement coverage is worked out for the total ankle market, the numbers may rise even more.