Of the forty-nine studies, ten (20%) focused on total ankle arthroplasty and thirty-nine (80%) described ankle arthrodesis; 852 patients underwent total ankle arthroplasty and 1262 underwent arthrodesis. The majority of the arthrodesis studies (56%) were published between 1990 and 1997, whereas all ten of the total ankle arthroplasty studies were published more recently, between 1998 and 2005. The vast majority of studies were from single centers in the United States and Europe. Other geographic locations included Japan and Taiwan.
There were no studies directly comparing total ankle arthroplasty and arthrodesis. Three non-randomized controlled trials of ankle arthrodesis compared different surgical techniques for arthrodesis. The duration of follow-up ranged from two to nine years in the studies of total ankle arthroplasty and from two to twenty-three years in the studies of arthrodesis. The average follow-up time following the total ankle arthroplasties and the arthrodeses was approximately five years.
All ten studies of total ankle arthroplasty (including a total of 852 patients) focused on second-generation total ankle implants. Information on the implants and the methods of fixation used in the total ankle arthroplasties is also displayed in Table I.
Patient characteristics were minimally described in the studies. In those in which the age of the patient population was reported, the mean overall age was fifty-three years (mean range, eighteen to sixty-four years) (see Appendix). The patients treated with total ankle arthroplasty were older (mean age, fifty-eight years; mean range, forty-six to sixty-four years) than those treated with ankle arthrodesis (mean age, fifty years; mean range, eighteen to sixty-three years) and were predominately female (59%). The majority of the patients in the arthrodesis studies were male (52%). Rheumatoid arthritis was the primary indication for the total ankle arthroplasties (39%), whereas posttraumatic arthritis was the primary indication for the arthrodeses (57%).
The reporting of efficacy outcomes was highly variable in both the total ankle arthroplasty and the ankle arthrodesis studies; therefore, the analyses performed in the present study were limited. The AOFAS Ankle-Hindfoot Scale total score and pain, function, and alignment subscores; the Kofoed scores for pain and function; and the range of motion (overall and plantar flexion-dorsiflexion) were among the most frequently reported evaluation methodologies. Table II presents both the raw means for these outcomes and the pooled meta-analytic results for the AOFAS total score and the range-of-motion outcomes for both total ankle arthroplasty and ankle arthrodesis. The meta-analysis mean AOFAS score was 78.2 points (95% confidence interval, 71.9 to 84.5) for the group treated with total ankle arthroplasty and 75.6 points (95% confidence interval, 71.6 to 79.6) for the group treated with ankle arthrodesis. The raw mean scores on the individual AOFAS subscales for pain, function, and alignment were 34.5, 37.4, and 9.4 points, respectively, in the group treated with total ankle arthroplasty. In the arthrodesis group, the raw mean Kofoed scores for pain and function were 32.5 and 15.7 points, respectively. Because of the lack of reporting of variances, meta-analysis of the subscale scores was not possible.
In the studies of total ankle arthroplasty in which excellent, good, fair, and poor categories were used as overall outcome measures, the result was excellent in 38% of the patients (95% confidence interval, 0% to 96.8%), good in 30.5% (95% confidence interval, 21.0% to 39.9%), fair in 5.5% (95% confidence interval, 0% to 16.9%), and poor in 24% (95% confidence interval, 0% to 72.9%). In the arthrodesis group, the pooled outcomes were excellent in 31% (95% confidence interval, 19.8% to 41.5%), good in 37% (95% confidence interval, 26.4% to 47.3%), fair in 13% (95% confidence interval, 6.2% to 20.3%), and poor in 13% (95% confidence interval, 7.6% to 18.7%).
The authors of several studies used different categorizations of overall patient outcomes (e.g., good-to-excellent results); therefore, in order to include these studies in the analysis, outcomes were combined into two wider categories: good (including both excellent and good results) and poor (including both fair and poor results). The meta-analysis of this binary outcome (Table III) showed that, in the studies of total ankle arthroplasty, 78% (95% confidence interval, 61.9% to 95.0%) of the patients had a good result and 22% (95% confidence interval, 4.9% to 38.6%) had a poor result. In the arthrodesis studies, 73% (95% confidence interval, 61.2% to 84.1%) had a good result and 27% (95% confidence interval, 16.0% to 38.8%) had a poor result.
Data on implant survival, revisions, conversions to arthrodesis, and other clinical outcomes after the total ankle arthroplasties and ankle arthrodeses are presented in the Appendix. The five-year and ten-year implant survival rates following total ankle arthroplasty were 78% (95% confidence interval, 69.0% to 87.6%) and 77% (95% confidence interval, 63.3% to 90.8%), respectively. A revision during the follow-up period was required in 7% (95% confidence interval, 3.5% to 10.9%) of the patients who had undergone a total ankle arthroplasty. The most common reason for revision was loosening and/or subsidence (28%). Five percent (95% confidence interval, 2.0% to 7.8%) of the total ankle arthroplasties were converted to arthrodeses, with the main reason for conversion being loosening and/or subsidence (50% of all conversions). Below-the-knee amputation was performed in 1% of the patients treated with total ankle arthroplasty.
Nonunion was observed in 10% (95% confidence interval, 7.4% to 12.1%) of the patients treated with ankle arthrodesis. Nine percent (95% confidence interval, 5.5% to 11.6%) of the arthrodesis group underwent revision, primarily because of nonunion (the indication for 65% of all revisions of arthrodeses). Five percent of the patients treated with ankle arthrodesis underwent a below-the-knee amputation. Significant heterogeneity was detected in almost all of these meta-analyses; therefore, the results must be interpreted with caution.
To our knowledge, this is the first systematic review of the intermediate and long-term outcomes of total ankle arthroplasty and ankle arthrodesis. Baseline differences in the patient populations and the small number of studies contributing to each analysis do not permit formal comparison between the two surgical procedures. However, the intermediate and long-term outcomes analyzed in this review do suggest that total ankle arthroplasty is comparable with ankle arthrodesis.
The strengths of this review include the clear definition of the research question to eliminate bias in the selection of the studies, adherence to an explicit research protocol that was developed prior to the analysis, the comprehensive nature of the literature search (with use of both electronic databases and manual bibliography searches), consensus between the two reviewers with regard to all data elements prior to entry into the database, and a quality-control review of all results. However, despite the strengths of the review process, they cannot overcome the inherent weaknesses in the literature.
The primary limitation of this review is that a direct comparative meta-analysis of total ankle arthroplasty and arthrodesis was not possible because there were no head-to-head trials. We were only able to perform a pooled meta-analysis across all studies, with many studies being devoid of key data elements, including methodology reporting and baseline patient information. In addition, the variability of the reporting of outcomes of interest limited the number of studies for each meta-analysis. In fact, differences in patient populations, variability of surgical procedures, and differences in outcome evaluation tools and study follow-up times may all be partially responsible for heterogeneity among these studies. In future studies, it will be important to use uniform evaluation tools to make comparisons easier.
This study exposed the major lack of objective, prospective, and controlled data on either procedure. The findings of this review demonstrate that the available data on the results of these procedures are based predominantly on retrospective uncontrolled case series from single institutions. The sample sizes in many of the studies were small. Therefore, prospective studies are needed to compare the two procedures in similar patient groups.
Despite these limitations, this study provides evidence that both procedures yield satisfactory results, and the data suggest equivalence between the procedures, negating the poor connotations associated with ankle arthroplasty due to failures associated with first-generation implants. In fact, while all patients may not be candidates for ankle arthroplasty, it should be considered as a treatment option for those with ankle arthritis, with the clinician being allowed the latitude to determine appropriate indications.
Tables presenting the patient characteristics and the clinical outcomes from the combined studies as well as a list of the studies that were evaluated are available with the electronic versions of this article, on our web site at jbjs.org (go to the article citation and click on “Supplementary Material”) and on our quarterly CD-ROM (call our subscription department, at 781-449-9780, to order the CD-ROM). ▪
Disclosure: In support of their research for or preparation of this work, one or more of the authors received, in any one year, outside funding or grants in excess of $10,000 from DePuy Orthopaedics, a Johnson and Johnson Company. In addition, one or more of the authors or a member of his or her immediate family received, in any one year, payments or other benefits in excess of $10,000 or a commitment or agreement to provide such benefits from a commercial entity (DePuy Orthopaedics). No commercial entity paid or directed, or agreed to pay or direct, any benefits to any research fund, foundation, division, center, clinical practice, or other charitable or nonprofit organization with which the authors, or a member of their immediate families, are affiliated or associated.
A video supplement related to the subject of this article has been developed by the American Academy of Orthopaedic Surgeons and JBJS and is available for viewing in the video library of the JBJS website, www.jbjs.org. To obtain a copy of the video, contact the AAOS at 800-626-6726 or go to their website, www.aaos.org and click on Educational Resources Catalog.
Investigation performed at Illinois Bone and Joint Institute, Glenview, Illinois, and United BioSource Corporation, Medford, Massachusetts
1. , Vertullo CJ, Urban WC, Nunley JA. Total ankle arthroplasty. J Am Acad Orthop Surg. 2002;10: 157-67.
2. , Lee TH. Total ankle arthroplasty: indications, results, and biomechanical rationale. Am J Orthop. 2000;29: 593-602.
3. , O'Malley MJ. Total ankle arthroplasty. Orthop Nurs. 2001;20: 30-7.
4. , 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: 1410-20.
5. , Mulrow CD, Haynes RB. Systematic reviews: synthesis of best evidence for clinical decisions. Ann Intern Med. 1997;126: 376-80.
6. , Green S, Higgins JPT, editors. Cochrane Reviewers' Handbook 4.2.1 [updated December 2003]. In: The Cochrane Library, Issue 1. Chichester, UK: John Wiley and Sons; 2004.
7. , Laird N. Meta-analysis in clinical trials. Control Clin Trials. 1986;7: 177-88.
Copyright 2007 by The Journal of Bone and Joint Surgery, Incorporated
8. , Olkin I. Statistical methods for meta-analysis. Orlando, FL: Academic Press; 1985. p 230-57.