The presence of retained metalwork, previou fractures or osteotomies makes TKA surgery challenging. Obstructed intramedually canals can produce difficulty with the use of IM instrumentation whilst the altered alignment can result in problematic soft tissue balancing.

We present a series of 35 patients with deformity who underwent a successful TKA.

Between July 2003 and January 2006 35 patients were operated on between 3 centres. All had extraarticular deformities in either the femur or tibia due to previous fractures or exposure to surgery. All underwent TKA surgery using an image free computer navigation system and extramedullary TKA instrumentation. All patients underwent pre-op and post-operative long eg alignment films.

The pre-operative long eg films showed an alignment of 16 degrees varus to 18 degrees of valgus. Post-operative alignment ranged from 3 degrees varus to 4 degrees valgus. The femoral component position ranged from 88-91 degrees from the mechanical axis whilst the tibial component position ranged from 89-92 degrees from the mechanical axis of the limb.

Total knee arthroplasty in the presence of extraarticular deformity is fraught with problems in regaining limb alignment and soft tissue balancing. This is the largest combined series of patients in which the same navigation system has been used to provide extramedullary alignment and cuts resulting in excellent component positioning and post-operative alignment. We recommend the routine use of computer navigation in these difficult cases.