Ankle replacement tiptoes into the mainstream

Janis Kelly

August 02, 2004

Aug 2, 2004

Total ankle joint replacement is increasingly seen as a reasonable option for patients with disabling ankle arthritis. In 5-year follow-up data presented July 25 at the American Orthopaedic Foot and Ankle Society (AOFAS) meeting and also published in the June 2004 issue of the Journal of Bone and Joint Surgery, Dr Stephen I Knecht (University of Iowa, Iowa City) and colleagues report that the second-generation Agility Total Ankle System prosthesis (Depuy, Warsaw, IN) had a long-term failure rate of only 11% and high patient satisfaction [ 1 ]. Dr Charles Saltzman (University of Iowa), senior author on the Knecht paper, notes, however, that failure rates are higher in younger patients and that ideal candidates are older, relatively inactive people with end-stage arthritis. Dr Adrienne A Spirt (University of Washington, Seattle), using a broader group of patients, found that over one quarter of patients required second operations, especially patients under age 54 [ 2 ].

Patients need to be realistic about the limitations and expectations with the use of an ankle replacement, but it is a viable option to treat people with debilitating end-stage ankle arthritis.

"Patients need to be realistic about the limitations and expectations with the use of an ankle replacement," Saltzman tells rheumawire , "but it is a viable option to treat people with debilitating end-stage ankle arthritis."


Long-term follow-up shows 90% of patients satisfied with total ankle replacements

Saltzman's report includes an additional 5 years of follow-up on 132 arthroplasties that were performed in 126 patients between 1984 and 1994 by Dr Frank Alvine. Alvine helped develop this device, which is the most widely used ankle implant in the US. Earlier data on the first 100 patients had been reported by Pyevich et al in 1998 [ 3 ].

The median follow-up was 9 years. Saltzman reports that during this period 33 patients died without requiring revision or having failed implants, 14 (11%) required revisions of their ankle replacements, and 1 underwent leg amputation due to unrelated causes. Of the remaining 78 patients, 67 (69 ankles) were followed clinically. "More than 90% of them reported that they had decreased pain and were satisfied with the outcome of the surgery," Saltzman says. There were relatively low rates of hindfoot arthritis. Of ankles followed radiographically for at least 2 years, 22 (19%) had subtalar arthritis, 17 (15%) had progressive talonavicular arthritis, and 9 (8%) had a syndesmosis nonunion. Three quarters of the ankles had some evidence of radiolucency around the implant, an indication of peri-implant bone loss.


Failure rate with new design is down to 11%

"The results of total ankle replacement are encouraging," Saltzman said. "The new failure rate is 11%, an improvement from previous reports. This suggests that the newer designs are having good midterm outcomes." Although this is higher than failure rates for total knee or hip replacements, Saltzman thinks the implant is better than joint fusion for selected patients.

The Agility implant consists of a titanium tibial component with sintered titanium beads and a cobalt-chromium talar component with sintered cobalt-chromium beads. A polyethylene insert locks into the tibia component, and the tibial component is stabilized by fusion of the distal tibiofibular syndesmosis.

All patients in this study had debilitating arthritis. Most (46%) had posttraumatic arthritis. Others had primary osteoarthritis (29%), rheumatoid arthritis (23%), and postinfectious arthritis (2%). The average age of these patients at the time of surgery was 61 years.

Fourteen of 132 ankles (11%) had required major revisions, defined as removal or replacement of part or all of the implant. Seven ankles had new implants, and 7 had the implants removed and had arthrodeses. Saltzman reported that 5 implants failed due to impaction or settling, 4 failed due to loosening and migration, and 2 failed due to tibial component fracture. This represents a major improvement over the 41% failure rate reported with first-generation ankle arthroplasties.

Three patients had postoperative wound complications, all of which resolved with oral antibiotics and standard local wound care.


The older the better

Spirt and colleagues reported similar data for 306 consecutive primary total ankle arthroplasties performed using the Agility implant between 1995 and 2001. Mean follow-up time was 33 months. Patients in this study were younger than those in the Saltzman study (53.5 years). Most needed ankle replacement due to posttraumatic osteoarthrosis (65%), primary osteoarthrosis (25%), prior ankle arthrodesis (5.6%), systemic joint disease (4.2%), or both posttraumatic osteoarthrosis and systemic joint disease (1 patient). In all cases, the indication for total ankle arthroplasty was severe refractory pain in the ankle joint associated with radiographic evidence of degenerative joint changes or patient dissatisfaction with a previous ankle arthrodesis.

Of the patients, 58% also had adjuvant surgery at the time of total ankle arthroplasty to correct major malalignment, instability, muscle imbalance, or joint contracture. Of note, these patients were not an increased risk for reoperation or implant failure.

Spirt et al reported that 28% of patients required reoperations, most commonly debridement of heterotopic bone, correction of axial malalignment, or replacement of components of the implant. The most common indication for reoperation was substantial ongoing ankle pain that was refractory to pain-management measures and associated with radiographic or clinical evidence of complications or failure. Most patients (57) required only 1 reoperation, but 18 had 2 reoperations, 9 patients had 3 reoperations, and 1 patient had 7 reoperations.

Of 306 patients, 8 ultimately required below-the-knee amputations. Of these 8, 7 had a history of severe trauma and multiple surgical procedures before the total ankle arthroplasty, and all but 1 had been considering amputation as a surgical option before the arthroplasty. "No patient with normal preoperative alignment underwent an amputation," Sprit notes.

Age at the time of arthroplasty was the only significant predictor of reoperation and failure. Spirt reported that each additional year of age decreases the risk of reoperation by 1.9% (p<0.05) and the risk of implant failure by 3.5% (p<0.05). Patients age 54 or younger had a 1.45-times greater risk of reoperation and a 2.65-times greater risk of implant failure than did patients older than 54 (p<0.05).


Really good surgeon needed

Dr Sigvard T Hansen (University of Washington, Seattle), senior author on the Spirt paper, points out in an accompanying commentary that there is a powerful need for need for an alternative to ankle fusion because patients strongly resist the recommendation for fusion and because after an average of 10 years, even patients with "good" fusions tend to become disabled by more distal arthrosis [ 4 ]. Hansen explains that his patients (drawn from a series of more than 600 primary cases) met less selective selection criteria than those in the Saltzman study and that, since the ankle replacements were performed at a teaching institution, there were "many hands on the tools."

This perhaps more real-world setting revealed several issues not raised in the series of patients operated on by Alvine.

"First," Hansen says," the technique is very technically demanding. . . . [M]uch of the operation involves balancing the musculature of the foot either as part of the arthroplasty or as a separate procedure." Like Saltzman, Hansen found that younger, active patients were likely to have more problems with ankle-replacement implants. They were more likely to have lytic areas filled with a caseous brownish material that contained refractive particles, assumed to be the result of polyethylene wear.

"Our most important finding has been that most failed ankles can be quite easily and very successfully revised instead of fused, and our rate of revision to fusion is nearly 10:1," Hansen says.


Sources

  1. Knecht SI, Estin M, Callaghan JJ, et al. The Agility total ankle arthroplasty: seven to sixteen-year follow-up. J Bone Joint Surg Am 2004; 86-A:1160-1171. 

  2. Spirt AA, Assal M, Hansen ST.  Complications and failure after total ankle arthroplasty. J Bone Joint Surg Am 2004; 86-A:1172-1178. 

  3. Pyevich MT, Saltzman CL, Callaghan JJ, Alvine FG. Total ankle arthroplasty: a unique design. Two to twelve-year follow-up. J Bone Joint Surg Am 1998;80:1410-1420. J Bone Joint Surg Am  1998; 80:1410-1420. 

  4. Hansen ST.  Commentary & Perspective on "The Agility total ankle arthroplasty: seven to sixteen-year follow-up" by Stephen I Knecht, MD, et al (editorial). J Bone Joint Surg Am 2004;  Available at: http://www.jbjs.org/Comments/2004/cp_jun04_hansen.shtml

 

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