Radiological assessment of the position of the tibial tuberosity by means of a marking wire in knees with patellofemoral arthritis

Objective. To assess the usefulness of a new axial radiographic technique in knees with patellofemoral arthritis (PF-OA). Design and patients. After a marking wire had been attached to the skin on the tibial tuberosity so that the wire matched the width of the patellar tendon, an axial radiograph was taken at 30° of flexion in 16 normal knees and 14 PF-OA knees in which computed tomographic analysis had revealed a laterally positioned tibial tuberosity at 30° of flexion. The distance of the marking wire from the lateral condyle and from the patellar groove was compared between the two groups. Results. The marking wire was located significantly laterally in PF-OA knees compared with normal knees. Conclusion. An axial radiograph with a marking wire on the tibial tuberosity is useful for assessing the position of the tibial tuberosity in PF-OA knees.