One of major problems in Total Hip Arthroplasty is thigh pain. We have examined the effect of femoral canal injection of Calcium Phosphate Paste (CPP) for cementless THA. CPP is a mixture of alpha Tri-Calcium Phosphate, Tetra-Calcium Phosphate, Calcium Hydrogen Phosphate and Hydroxyapatite. This paste harden in 10 minutes and its stiffness increases to 80Mpa in 3days.

Cementless THA were performed in 45 osteoarthritic hips from 1999 to 2002. Eight of 40 patients were male and 32 were female, average age were 62.4 years old ranged 43 to 81. In 11 hips, CPP (10–12g) were filled as a femoral canal filler around the distal end of stem. In 34 hips, as a control, no CPP were filled in the canal. Proximal part of the stem was HA coated on rough metal surface.

No thigh pain were observed in CPP group patients. In control group, five hips (14.7%) showed thigh pain (p< 0.05), but walking disability and pain were mild in the first year and improved by the next year. CPP filled in the canal were absorbed slowly on X-ray film, but prevention of thigh pain lasts for long time maximum 3 years. No infections and pulmonary embolism were observed in both series.

Filling CPP into the gap between stem tip and femoral canal is useful technique to prevent thigh pain after cementless THA.