[Patella in Place Balancer: Technique for total knee arthroplasty].

BACKGROUND: The gap-balancing technique is well established in primary total knee arthroplasty to determine femoral rotation and flexion gap stability. However, it has been reported that the everted or luxated extensor mechanism during this procedure in addition to soft tissue releases performed may cause inaccurate flexion-gap determination and thus result in malpositioning of the femur or instability. In this article the alternative technique of a Patella in Place Balancer (PIPB) with a no tissue release philosophy is introduced.
METHOD: In this procedure, at first, the tibia resection is performed and a tibia baseplate inserted. Then, two pins are drilled into the sagittal profile of the femoral condyles. After anatomical repositioning of the extensor apparatus the pins are screwed in until the flexion gap is spanned. In this position femoral component orientation is determined parallel to the tibia. We describe the current clinical experience based on a retrospective review of 3,000 patients. Moreover, initial results of a prospective study are outlined.
RESULTS: The PIPB technique was suitable for the treatment of primary and secondary gonarthrosis if the collateral ligaments were intact. The detected revision rate was about 1.21 %. Only 2 % of the treated patients reported back with an unsatisfactory outcome 1 year after surgery. In the prospective survey of 33 patients a significant improvement in the KOOS Score could be documented (29.3 points preoperatively vs. 63.5 postoperatively (p < 0.05)). DISCUSSION: The PIPB overcomes the major limitation of the gap balancing technique with regard to the inaccuracy caused by the dislocated extensor mechanism. After a learning curve, the technique appears to be safe and reliable. Preliminary data show promising results.