Abstract
Introduction and aims
Recently many implants for ankle arthroplasty have been developed around the world, and especially some mobile bearing, three-component implants have good results. Nevertheless, at our institution fixed two-component, semi-constrained alumina ceramic total ankle arthroplasty (TAA) with TNK Ankle had been performed since 1991 and led to improved outcomes. We report clinical results and in vivo kinematic analyses for TNK Ankle.
Method
Between 1991 and 2006, total ankle arthroplasties with TNK Ankle were performed with 102 patients (106 ankles) with osteoarthritis at our institution. There were 91 women and 11 men. The mean age was 69 years and mean follow-up was 5.4 years. These cases were evaluated clinically and radiographically. Besides in vivo kinematics, in TNK Ankle was analysed using 3D-2D model registration technique with fluoroscopic images. Between 2007 and 2008, prospectively ten TAA cases examined with fluoroscopy at postoperative one year.
Results
In clinical results, excellent were 48 cases, good were 31 cases, fair were 10 cases, poor were nine cases, and death and loss to follow-up were 10 cases. Reoperations are performed on eight cases, one was arthrodesis, seven were talar component revision or talar revision with ceramic whole talus prosthesis. TNK Ankle have the rough surfaces by beadworks, and added surface treatment with hydroxyapatite granules, calcium phosphate paste or tissue engineered mesenchymal cells. Recently, only talar components were fixed with bone cement. Loosening has been more frequent in talar than tibial, whereas no reoperation was on cemented talar component cases. According to 3D-2D model registration, both components rotated a little each other and the contact region between both components variously sifted during weight bearing flexion of ankle. It was supposed that replaced position and angle of components concerned with the contact region.
Conclusions
TAA with TNK Ankle have led to better results with improvement for surface treatments. Kinematics of ankle prostheses was derived by 3D-2D model registration, more appropriate position and angle to replace.
