Stem length and canal filling in uncemented custom-made total hip arthroplasty

We reviewed 60 custom-made femoral components of two different lengths : 125 mm (group A) and 100 mm (group B), in order to investigate the relationship between stem length and canal filling in uncemented custom-made total hip arthroplasty. There were no statistical differences between the two groups in age, gender, height, body weight, canal flare index, or bowing angle of the femur. Postoperatively there was no statistical difference between the two groups in the proximal canal filling, but significant difference in the distal canal filling (75.5% vs 85.8% on the anteroposterior view and 76.0% vs 82.5% in the lateral view, P<0.001). The distal canal filling inversely correlated with the ratio of the proximal portion and the distal portion of the stem curvature on the lateral view (lateral curve ratio of the stem, P=0.002). We conclude that superior filling at both the proximal and the distal levels can be obtained by using 100-mm custom made components with a small lateral curve ratio.