[Conventional navigation without computer and the lateral minimally invasive approach for contract valgus knee].

Valgus arthritic knees can basically be operated on by either a standard medial or a specific lateral approach. The classic lateral approach according to Keblish has some advantages, but also some disadvantages, relative to the standard medial parapatellar approach. A less invasive lateral approach means that osteotomy of tibia tubercle and eversion of the patella is no longer necessary. In view of our positive experiences with the minimally invasive surgical technique used for implantation of the lateral unicondylar prosthesis and for total knee arthroplasty in the case of varus knees, we have developed a minimally invasive lateral technique for use in valgus knees. The approach is a modification of the classic lateral approach used by Keblish. The procedure involves a lateral mini-arthrotomy with no need for osteotomy of the tubercle or eversion of the patella, and the surgery takes place step by step from a lateral approach. Modified cutting standard instruments are used. All operations have been carried out using "conventional navigation" without computers. This consists in preoperative planning based on radiographs of the whole leg, intraoperative controls before and after bone cuts, planning of the rotational positioning of the femur and tibia and postoperative checks of the alignment on standing radiographs of the whole leg. Preliminary results observed in the first 63 consecutive patients (average age 45-85 years) with contract valgus deformity [average 12 degrees valgus (6-19 degrees )] are very promising. Since 2004 we have used minimally invasive medial and lateral mini-midvastus approaches routinely for nearly all our primary total knee arthroplasties.