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

ABSTRACT

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.