Total ankle arthroplasty is increasingly used as an alternative to arthrodesis to treat advanced ankle arthritis. In an attempt to assess the survivorship and patient outcome as well as peri- and postoperative complications and possible risk factors, we retrospectively analyzed the demographics, clinical outcome and radiographic characteristics of 100 ankle prostheses (97 patients). Between 3/2005 and 5/2010 114 S.T.A.R. Prostheses were implanted by one surgeon at our institution. Indication for TAA was primary and secondary osteoarthritis, 81 cases were posttraumatic. From the 53 female and 44 male patients the mean age was 63 and the mean BMI was 28,4. 11 patients had been smoking for longer than 12 years, 29 patients either had a history of diabetes, peripheral vascular or cardiovascular disease or varicosis. All operations were performed with a tourniquet, using a standard anterior midline incision. All patients received the same postoperative rehabilitation and follow up program. Postoperative evaluation included the AOFA Score and clinical radiographic follow ups 6 weeks after surgery and yearly thereafter. Additional procedures during surgery included lengthening of the Achilles tendon for 12 patients and fusion of the subtalar ankle for 5 patients.Introduction
Patients and methods
Our aim was to compare the passive kinematics and coronal plane stability throughout flexion in the native and the replaced knee, using three different TKA designs: posterior stabilized (PS), bi-cruciate substituting (BCS), and ultracongruent (UC). Our hypotheses were: 1.) a guided motion knee replacement (BCS) offers the closest replication of native knee kinematics in terms of femoral rollback 2.) the replaced knee will be significantly more stable in the coronal plane than the native knee; 3.) No difference exists in coronal plane stability between the 3 implants/designs throughout flexion. After IRB approval, two cadaveric specimens were used for a pilot study to determine sample size. Five fresh-frozen hip-to-toe cadaveric specimens then underwent TKA using an anatomic measured resection technique with a computer-navigated robotic femoral cutting-guide. The PS, BCS, and UC TKA designs were implanted in each knee using the same distal and posterior femoral cuts to standardize the position of the implants. Computer navigation was then utilized to record the varus/valgus laxity of each implant at 0°, 30°, 60° and 90° of flexion while applying a standardized 9.8Nm moment. Passive tibiofemoral kinematics were measured in a continuous passive motion machine from 10° to 110°. Femoral rollback on the tibia was calculated for the native and replaced knees by measuring the closest point (CP) on the femoral condyle to a transverse plane perpendicular to the mechanical axis of the tibia at each flexion angle.Purpose
Methods
