Alignment of the lower extremity mechanical axis by computer-aided design and application in total knee arthroplasty

The success of total knee arthroplasty (TKA) depends on many factors. The position of a prosthesis is vitally important. The purpose of the present study was to evaluate the value of a computer-aided establishing lower extremity mechanical axis in TKA using digital technology.

A total of 36 cases of patients with TKA were randomly divided into the computer-aided design of navigation template group (NT) and conventional intramedullary positioning group (CIP). Three-dimensional (3D) CT scanning images of the hip, knee, and ankle were obtained in NT group. X-ray images and CT scans were transferred into the 3D reconstruction software. A 3D bone model of the hip, knee, ankle, as well as the modified loading, was reconstructed and saved in a stereolithographic format. In the 3D reconstruction model, the mechanical axis of the lower limb was determined, and the navigational templates produced an accurate model using a rapid prototyping technique. The THA in CIP group was performed according to a routine operation. CT scans were performed postoperatively to evaluate the accuracy of the two TKA methods.

The averaged operative time of the NT group procedures was [Formula: see text] min shorter than those of the conventional procedures ([Formula: see text]  min). The coronal femoral angle, coronal tibial angle, posterior tibial slope were [Formula: see text], [Formula: see text], [Formula: see text] in NT group and [Formula: see text], [Formula: see text], [Formula: see text] in CIP group, respectively. Statistically significant group differences were found.

The navigation template produced through mechanical axis of lower extremity may provide a relative accurate and simple method for TKA.