Introduction: Optimal component position in all planes and well balanced soft tissues lead to a good clinical outcome and long-term survival after total knee arthroplasty. We investigated the implantation accuracy of navigated total knee arthroplasty at 3 months followup and the influence on the clinical outcome at 2 years followup.

Patients and Methods: Forty-four patients (44 procedures) were enrolled in our prospective study. One half of the surgeries were performed using a computed tomography based navigation system, and one half of the surgeries were performed without computed tomography navigation. Outcomes were based on the Insall knee score parameters, anterior knee pain, patient satisfaction, feeling of instability, and step test. The radiographic parameters were the mechanical axis, tibial slope, lateral distal femoral angle, and medial proximal tibial angle.

Results: The radiographic measurements showed no differences between both groups (patients within ± 3° inaccuracy range in computed tomography based/computed tomography free groups; mechanical axis 86%/81%, tibial slope 95%/91%, lateral distal femoral angle 95%/91%, medial proximal tibial angle 91%/95%). The cumulative error of alignment showed no difference between the study groups. Seventeen of 21 (81%) patients fulfilled four criteria in the CT based group, and 15 of 21 (71.4%) patients fulfilled four criteria in the comparison group. Nineteen of 21 (90.5%) patients in both groups achieved three criteria in an optimal manner. An increased (p < 0.001) Insall knee score was found for changes over time in both study groups; however, there were no differences between the CT based or CT free patient groups. The postoperative ROM in both groups showed no difference at the 3-month and 2-year followup examinations. Both groups had an increase (p ≤ 0.002) in ROM between the 3-month and 2-year followup examinations. The examination of ligament balancing in full extension showed a higher rate of a stable soft tissue situation in the CT free navigation group but the difference was not significant. In 30° of flexion we detected a better (p = 0.004) ligament situation medially and laterally in the CT free group. The anterior drawer test showed a better (p = 0.035) stability in the CT free navigation group.

Discussion: The computed tomography free system provided equal radiographic results, but we found improved ligament balancing in the computed tomography free group. The computed tomography based module has an optimal preoperative planning procedure, but is more expensive and time consuming.

Introduction: Existing data in the literature is supporting either patellar retention or patellar resurfacing during primary TKA. There is no clear answer for the question in which cases the patella should be retained or resurfaced during primary TKA.

Materials and Methods: In this prospective study 2 groups of patients with a mean follow up of 34 months after TKA were compared. 83 patients (98 TKA) were implanted with a TKA with patellar retention (group 1) while 93 TKA (86 patients) were done including a patellar resurfacing (group 2). The patients were randomized according to the year of birth. The NexGen® MBK and the LPS were implanted. A dome shaped patellar prosthesis with 3 pegs was used for patellar resurfacing. Clinical Outcomes were based on the knee society score parameters, anterior knee pain, patient satisfaction, feeling of instability, step test while component position and limb alignment were measured by standard radiographs.

Results: No statistical differences between both groups with regard to post-operative anterior knee pain and knee society score were found. We found no pre-operative predictor factors for the development of post-operative anterior knee pain for each group and both together. Patellar maltracking was worse in group 1 than in the resurfaced group (3 cases with patellar subluxation in group 1 versus 2 cases in group 2).

Conclusion: According to the not significant differences for the clinical outcomes between group 1 and 2 we routinely retain the patella. Patellar resurfacing is done only in selective cases.

Introduction: The benefits of postoperative wound drainage in patients with total knee arthroplasty (TKA) with regards to mobilisation and wound healing were studied. We wanted to determine the efficacy of an autologous blood retransfusion system.

Materials and Methods: 150 patients with TKA were divided into three groups of 50 patients:

A) Three wound drainages with an autotransfusion system and suction;

Haemoglobin values, blood transfusion requirements, blood loss, postoperative range of motion, knee society score and rate of complications were observed and recorded. All patients were operated without tourniques for lower blood loss during total knee replacement.

Results: In the group of patients with wound drainage and a retransfusion system the requirement of postoperative additional blood transfusion was not significantly less than in the group without wound drainage. Group A had the most blood loss of all. The group without wound drainage had more haematoma and wound healing complications. Best results were observed within the group with one intraarticular drainage without suction. The rate of complications was not increased and the blood transfusion requirements were the lowest.

Conclusion: This study shows that total knee replacement involving one intraarticular wound drainage without suction attains the best results. During the last four years we used this wound drainage technique in 787 TKAs and can confirm all findings of this study.