Accuracy of Intramedullary versus Extramedullary Tibial Alignment Guides: A Randomized, Prospective Study in Bilateral Total Knee Arthroplasty

Han, Hyuk Soo; Cho, Young Jae; Yoon, Kang Sup; Lee, Ji Ho; Lee, Jae Hyup; Jo, Hyun Chul; Kang, Seung Baik

Abstract

PURPOSE: To determine which one is more accurate tibial cutting system for total knee arthroplasty between intramedullary and extramedullary alignment guides in Korean osteoarthritis patient.
MATERIALS AND METHODS
A prospective study of 80 consecutive total knee arthroplasties in 40 patients with bilateral osteoarthritis of knee was carried out. All patients were undertaken the total knee arthroplasty with intramedullary cutting system in randomly assigned side of the knee, and with extramedullary cutting system in the other side. A standing antero-posterior radiograph of whole lower extremity was performed at six months after operation, and tibia component angle(TCA) which represents the angle between the mechanical axis of tibia and transverse axis of the prosthetic knee joint was measured. The optimal values for TCA was defined as 90+/-4 degrees.
RESULTS
The mean values for the TCA in all cases was 89.3+/-1.9 degrees(82~ 96 degrees) and 93% of all patients were included in the optimal range. The TCA fell into the optimal range in 36 cases of 40 cases(90%) with extramedullary cutting system, while 38 cases of 40 cases(95%) with intramedullary cutting system. These differences were not statistically significant.
CONCLUSION
Both extramedullary and intramedullary alignment cutting systems are effective methods for Korean. In order to reduce the risk of malalignment, proper proximal tibia cutting method should be carefully selected according to the individual characteristics of the knee, and preoperative evaluation for alignment using radiograph is mandatory.