Outcomes and Complications of Four Total Ankle Arthroplasty
Authors: Rungprai Chamnanni , Hartog Taylor Den , Phisitkul Phinit , Femino John , Amendola Annunziato 
Published: October 2016

Category: Ankle Arthritis Introduction/Purpose: Total ankle replacement has been proven to be effective method for treatment of patient with end-stage ankle arthritis alternative to ankle fusion. STAR implant was initially used followed by SALTO, INBONE and ZIMMER implants. While four implants are currently used, there is a paucity of evidence in literature to compare outcomes and complications between them. Methods: Retrospective chart review of 247 consecutive patients with 258 arthritic ankles who were diagnosed with end-stage ankle arthritis and underwent total ankle replacement using STAR (98 ankles, 38.0%), SALTO (121 ankles, 46.9%), INBONE (24 ankles, 9.3%), and Zimmer (15 ankles, 5.8%) implants between October 1997 and May 2015. There was prospectively collected data and minimum follow-up for inclusion was 6 months with an average of follow-up of 101.2 months (range, 18 to 211 months), 52.3 (range, 6 to 90 months), 15.3 (range, 6 to 27 months), and 13.7 months (range, 6 to 26 months) for STAR, SALTO, INBONE, and ZIMMER, respectively). The primary outcome was Visual Analogue Scale (VAS), Foot Function Index (FFI, pain, disability, activity limitations, and total scores), Short Form-36 (SF-36, PCS and MCS), and the secondary outcomes included 2- year, 5-year, and 10-year survival rate, ankle range of motion at the final post-operative visit, and complications. Analysis of VAS, SF-36, and FFI was performed between the four groups using one-way ANOVA. Independent Sample T-test, Wilcoxon Rank Sum Test, and Chi-square test were used to compare other parameters and complications. Results: All four implants demonstrated significant improvement of functional outcomes (SF-36,FFI,VAS) (p < 0.001); however, there was no significant of outcomes and pain relief between each pair of implants (p > 0.05, all). The 2-year survival rates were 98.9%, 100%, 100%, and 100% for STAR, SALTO, INBONE, and Zimmer implants respectively. The 5-year survival rates were 91.7% and 96.2% and for STAR and SALTO implants respectively but 10-year survival was 86.1% for the STAR implant. Short- term complication for STAR, SALTO, INBONE, and ZIMMER implants were superficial wound infection (8.4%, 8.5%, 0%, and 0%), deep wound infection (2.1%, 1.7%, 0%, and 0%), medial malleolar fracture (6.3%, 6.8%, 0%, and 0%), lateral malleolar fracture (0%, 2%, 0%, and 0%), numbness on the incision (5.3%, 1.7%, 0%, and 0%), stiffness of the ankle joint (1.1%, 1.7%, 0%, and 0%), gutter impingement (14.7%, 2.5%, 0%, and 13.3%), talar component subsidence (9.5%, 0.8%, 0%, and 0%), and tibia component subsidence (4.2%, 3.4%, 0%, and 0%), polyethylene fracture (6.3%, 0%, 0%, and 0%). Conclusion: Based on our findings, all implants demonstrated significant improvement in term of functional outcomes, clinical outcomes, and pain relief as measured with FFI, SF-36, VAS scores, and range of motion of the ankle joint for treatment of end- stage ankle arthritis. The functional outcomes were comparable in all four types. Short-term complications were comparable in all groups but long-term complications of INBONE and Zimmer implants required longer follow-up time. Further prospective clinical investigation is important.