Three dimensional analysis of component placemenent at total knee arthroplasty and relationship between clinical outcomes

Manufacturers of total knee arthroplasty (TKA) have introduced narrower femurs and tibias to improve bone-implant fit. Residual pain during activities of daily living and/or at rest is a major cause of a patient's dissatisfaction after TKA. The management of a painful TKA, which has no obvious clinical or radiological explanation, requires further investigation with more sensitive imaging modalities. Our hypothesis was that component oversizing , rotational situations of tibial and femoral component, coronal , saggital and axial alingment errors can effect negatively influences the results after TKA. It is often challenging for the physician to determine what level of pain warrants these more complex and expensive medical examinations. One hundred and forty-six prospectively followed patients with 146 TKA were retrospectively assessed.The three dimensions of the femoral and tibial component alinments were measured on a postoperative CT-scan after 45.2 ± 9.5 after TKA surgery and were compared with patients outcome score. 101 patients presented tibia posterolaterally overhang and 76 patients presented femur laterally. We found that tibial and femoral component's overhang can reduce functional outcome and pain score , essipecially on posterolateral of tibia plateu. This study confirms that oversizing and malingment may lead to worse clinical results in TKA. The clinical consequences are that surgeons should pay attention not to oversize implants during implantation and that oversizing should be ruled out in case of so called unexplained pain.