A Comparison of Accuracy between the Sonography-guided Extramedullary and Intramedullary Alignment Systems for the Femoral Component in Total Knee Arthroplasty

PURPOSE: We wanted to compare the accuracy between a newly suggested sonography-guided extramedullary alignment guide system and an ordinary intramedullary alignment guide system for the femoral component alignment in Total Knee Arthroplasty (TKA). MATERIALS AND METHODS: Among the patients who underwent TKA from December 2006 to May 2007, an intramedullary technique was applied in 50 cases (the IM group) and an extramedullary technique was used in 50 cases (the EM group). The femoral component alignment angle was measured and compared postoperatively by using an anteroposterior (AP) radiograph of the knee. RESULTS: The average femoral component alignment angle was 94.96degrees (92~98degrees) in the IM group and 95.36degrees (90~99degrees) in the EM group. Both groups didn't show a significant difference. 45 cases (90%) in the IM group and 43 cases (86%) in the EM group were included in the optimal range of the femoral coronal angle (95degrees+/-2). CONCLUSION: There was no significant difference regarding the accuracy of the sonography-guided extramedullary and intramedullary femoral component alignment guide systems for performing Total Knee Arthroplasty.

A Comparison of Extramedullary and Intramedullary Femoral Component Alignment Guide Systems in TKA

PURPOSE: To compare a new extramedullary femoral alignment guide system with the conventional intramedullary alignment guide system for femoral component alignment in total knee arthroplasty(TKA). MATERIALS AND METHODS: From November 2004 to June 2005, a newly developed extramdullary technique was applied in 80 cases (EM group), which was compared to another 80cases (IM group) in which conventional intramedullary technique was used. Standing long leg anteroposterior (AP) radiographs were evaluated at postoperative 2 months to compare the alignment between the groups. And surgery time between two groups was compared. RESULTS: Femoral component alignment was 1.7+/-1.3degrees in EM group and 1.3+/-1.2degrees in IM group (p=0.025). Clinically acceptable femoral component alignment(<+/-3degrees) was achieved in 92% of EM group and 93% in IM group. The femoral component flexion angle was 3.9+/-2.3degrees delta in EM group and 5.5+/-2.7degrees delta in IM group (p<0.0001). The surgery time was 69+/-11.5 min in EM group and 68+/-11.7 min in IM group(p= 0.516). CONCLUSION: By using our EM technique, we could achieve a accurate alignment and similar surgery time compared with conventional IM technique, although it is not superior to IM technique. We think that our new extramedullary technique is a useful surgical method decreasing the complications of intramedullary canal injury.