[Comparison of Clinical Influence of Intramedullary versus Extramedullary Alignment Guides on Total Knee Arthroplasty]

Objective: To compare the clinical influence of intramedullary versus extramedullary alignment guides on total knee arthroplasty (TKA) in terms of alignment of the lower limbs,intraoperative tourniquet time,and postoperative complications.

We retrospectively analyzed the clinical data of 105 patients(210 knees)undergoing bilateral TKA from February 2012 to November 2013. All patients were divided to two groups:40 [age:(66.65 ± 9.57)years] were implanted using intramedullary guides on the tibia and 65 [age:(65.29±9.27)years] were implanted using extramedullary guides on the tibia. Alignment of lower limb,tibial component angle in the sagittal plane,tourniquet time,and postoperative complications were compared.

The gender ratio,age,height,weight,body mass index,and preoperative alignment of lower limbs were not significantly different between these two groups (all P>0.05). The average coronal alignment of lower extremity was (179.69 ± 2.91)° in the intramedullary guides group and (178.26 ± 3.38)° in the extramedullary guides group (P=0.002). The alignment of lower limbs on neutral and valgus position were found in 68 cases(85.00%)in the intramedullary group and in 94 cases (72.31%) in extramedullary group (P=0.033) ;the tourniquet time was (79.46 ± 12.06) min in the intramedullary group and (84.68 ± 8.02) min in the extramedullary group (P=0.001); the postoperative complication rate was 6.25% in intramedullary group and 3.07% in extramedullary group (P=0.279).

Alignment and tourniquet time can be significantly improved by the intramedullary instrumentation,while the incidence of complications associated with intramedullary instrumentation is higher than extramedullary instrumentation.