SLR - September 2013 - Randall Thomas
Reference: Schweitzer KM, Adams SB, Viens NA, Queen RM, Easley ME, DeOrio JK, Nunley JA. (2013). Early Prospective Clinical Results of a Modern Fixed-Bearing Total Ankle Arthroplasty. The Journal of Bone and Joint Surgery, 95:1002-11.
Scientific Literature Review
Reviewed by: Randall Thomas, DPM
Residency Program: Grant Medical Center, Columbus, OH
Podiatric Relevance: Foot and ankle surgeons have traditionally had limited treatment options for patients presenting with symptomatic, end-stage ankle arthritis. The scientific literature previously favored ankle arthrodesis and ankle arthrodiastasis when compared to total ankle arthroplasty, or total ankle replacement (TAR). Original generation TAR was cited as having high complication rates including reoperation, infection, hardware failure, and malalignment with overloading adjacent joints. Modern generation TAR in the United States commonly consists of a fixed-bearing, two-component design and has demonstrated in the recent scientific literature equivalent pain relief and improved functional outcomes as compared to ankle arthrodesis. Our institution has seen favorable results with modern generation TAR in the middle-to-old-aged patient with normal to low body mass index, quality bone stock, minimal deformities, poly joint arthritis, and no neurovascular impairment of the lower extremity. The authors in the above article prospectively followed 67 patients for a minimum of two years who underwent Salto Talaris TAR.
Methods: The authors performed 75 consecutive primary TAR with the Salto Talaris system from June 2007 to October 2009 at a single tertiary center. Each of the authors who performed the cases had individually conducted more than 400 TAR procedures. Patients included in the study had end stage ankle arthritis and failed conservative treatment with no evidence of infection, peripheral vascular disease, or uncontrolled diabetes mellitus. Patients were not offered TAR as a treatment option if they had inadequate bone stock or more than 20 degrees of coronal plane deformity. The surgical procedure was performed under general and regional anesthesia with preoperative antibiotics and the technique was based on the manufacturers published guide. All patients were admitted postoperatively to the hospital for observation and pain control. Postoperative day-one: the surgical drain was removed and patients worked with physical therapy to remain non-weight bearing to the surgical limb. Patients followed-up three weeks after surgery for removal of cast and inspection of surgical site then were placed again in a below knee cast or controlled ankle motion (CAM) boot. After six weeks, patients were removed from cast or CAM boot and began self directed range of motion exercise and weight bearing to tolerance. Postoperative clinical visits were conducted at six weeks, three months, six months, one year, and yearly thereafter in which patients completed standardized questionnaires at these intervals which were also done preoperatively, and patients underwent clinical and radiographic evaluation. Eight patients were lost to follow-up at less than two years post-op and were excluded from the study. For assessing functional outcomes, patients were evaluated preoperatively and postoperatively at the institution's human performance lab with detailed clinical exam and weight bearing radiographs, pain visual analog scale (VAS), American Orthopaedic Foot and Ankle Society (AOFAS) hindfoot scale, Short Form 36 (SF-36) Health Survey, the Short Musculoskeletal Function Assessment (SMFA) questionnaire, and the Foot and Ankle Disability Index (FADI) questionnaire. Patients completed standardized tests including sit-to-stand test, timed-up-and-go test, and average walking speed assessment. Statistical measures included repeated measures analysis of variance for significant differences and the Tukey post hoc testing with time points preoperatively and postoperatively.
Results: Mean clinical follow-up of 2.81 years with 18 men and 49 women and mean age of 63 years. Mean body mass index was 29.3 with 27 patients being lifetime smokers, 32 patients being previous smokers. Three patients were well-controlled Type 2 Diabetics and no Type I Diabetics underwent the procedure. One patient was on immunosuppressive medication. Forty-five of the 67 patients underwent at least one additional procedure during the TAR implantation including deep deltoid ligament release, hardware removal, gastrocnemius recession, prophylactic fixation of the medial malleolus when narrow, as well as two intraoperative malleolar fractures treated with internal fixation. Mean length of hospital stay was 1.5 days with one patient having a longer stay secondary to bilateral pulmonary emboli requiring anticoagulation. Eight patients underwent future additional surgery, most commonly exostectomy and debridement for impingement. Three patients developed progressive, aseptic tibial component loosening and one of the three required revisional TAR. No deep infections were reported. Three patients had delayed wound healing which healed with local wound care and oral antibiotics. One patient had a non-displaced distal fibular fracture which healed with a period of immobilization and non-weight-bearing. Three patients developed tarsal tunnel syndrome in which one required surgical intervention. One patient had a partially transected tibial nerve and residual numbness of the plantar foot. At mean follow-up of 2.81 years, implant survival was 96 percent. VAS scores for pain and SF-36 scores were significantly improved at each follow-up interval for two years. SMFA function and bother indices as well as mean AOFAS hindfoot total scores also showed significant improvement at all intervals for two years. Mean length of time until last postoperative radiographic evaluation was 2.79 years with a mean coronal alignment within the range of two degrees varus to two degrees valgus. Three patients developed tibial component loosening. Thirty-nine percent of patients had radiographic lucency around the tibial component and 15 percent of patients had lucency around the talar component. Functional assessment outcome with the sit-to-stand assessment significantly improved at the one year and two year follow-up intervals. Additionally, patients showed significant improvement in the time-up-and-go, mean walking speed, and FADI scores at the one year and two year postoperative intervals.
Conclusions: Review of the scientific literature cites modern TAR survival rates from 70 percent to 98 percent at three-to-six years with this article being the first published prospective evaluation with 96 percent implant survival rate. The article discussed 67 percent of cases requiring additional procedures during the TAR implantation which is a higher rate than previously reported for concomitant procedures. For the time period of follow-up, the reoperation rate is comparable to previous TAR literature which reports reoperation rates varying from two percent to 34 percent. Pain and function improvements were statistically significant postoperatively compared to preoperatively with all measures including walking speed increasing 41 percent at two years postoperatively. Limitations include short term follow-up and subjects being lost to follow-up as well as inherent varying skill level of surgeons performing the procedure and no control comparisons to conservative treatment only, ankle arthrodesis, and ankle arthrodiastasis. Future TAR research needs to be pursued involving long-term follow-up, determining preoperative factors which correlate with complications and failure, and prospective fixed bearing TAR versus mobile bearing TAR with outcomes. Overall, the article presents an initial prospective study of functional assessments of TAR preoperatively compared to postoperatively at two year follow-up.