Radiological evaluation of total knee arthroplasty

ABSTRACT

X-Ray analysis of a subset of TKA performed using a standard posterior cruciate ligament [PCL] retaining cemented technique to study the component malposition, overall post-operative alignment and mechanical loosening with respect to components positioning during follow-up period. This is a prospective study where we radiographically evaluated twenty-six primary TKAs [15 right and 11 left] in 20 patients [six patients received two stage bilateral total knee replacement] performed between July 2004 and December 2005. There were a total of 13 women and 7 men. The mean age at the time of the operation was 68 years and the follow-up period ranged from 18-32 months. The indication for knee replacement in all cases was advanced osteoarthritis. Radiographs were done immediately postoperative, at 6 weeks, at 3 months, at 6 months and then every year after surgery, and each time were compared to the postoperative controls. The overall alignment was acceptable in 19 knees, 3 had excessive valgus and 4 had varus alignment. At the last follow-up which was up to 32 months in some cases, none of the cases developed loosening as evidenced by non appearance of radiolucent zones or shifts in the position of the components. Moreover, the seven cases with joint malalignment didn't show signs of aseptic loosening within the available follow-up period. For the patellar angle, the mean tilt angle was 12° +/- 6°. In 17 knees the patellar prosthesis was displaced superiorly, and in seven cases there was medial displacement of the patellar prosthesis. Evaluation of total joint arthroplasty must be clinical, radiological and with annual intervals, in order to discover early failure signs. Proper alignments are critical for achieving good results thus keeping loosening to a minimum. Concerning the present study, aseptic loosening was not a complication of the toted knee arthroplasty evaluated at a follow-up period of up to almost three years in some cases, including those cases with documented postoperative joint malalignment