Two principal targets are dominating the spectrum of goals in total knee arthroplasty: first of all the orthopedic surgeon aims at achieving an optimal pain-free postoperative kinematic motion close to the individual physiologic range of the individual patient and secondly he aims for a concurrent high ligament stability within the entire range of movement in order to establish stability for all activities of daily living. This study presents a modified surgical procedure for total knee replacement which is ligament-controlled in order to put both component into the “ligamentous frame” of the patients individual kinematics. The posterior femero-condylar index (PFC-I) is defined as being the posterior condylar offset divided by the distal antero-posterior diameter on a lateral radiograph. After careful preoperative planning the positions and orientations of the osteotomies is controlled intraoperatively via ligamentous guidance. Anterior and distal femoral osteotomy are planned on antero-posterior and lateral radiographs considering intramedular and mechanical axes as well as the orientation of the posterior condyles. Osteotomies are carried out in a stepwise fashion, starting with the anterior femoral osteotomy followed by the distal femoral osteotomy as planned. Then the extension gap is finalized by tensioning the ligaments and “top-down” referencing the level of the tibial osteotomy. After rotating the femur into the 90°-flexion position the flexion gap is finalized by referencing the level of the posterior condyle osteotomy in a “bottom-up” fashion to the tibial osteotomy. Hence, this technique determines the size of the femoral component with the last osteotomy. It likewise respects the new, ACL-lacking ligamentous framework and it drives the prosthetic components to fit into the new ligamentous envelope to follow the modified kinematics.Introduction
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