COMPARISON OF BONE DENSITY IN CEMENTED AND UNCEMENTED TOTAL KNEE ARTHROPLASTY

Abstract

Few studies suggest that the use of a cemented stem reduces proximal stresses and may result in proximal bone resorption. Aim of our study: Does bone cement affect peri prosthetic bone density? The study was approved by the local ethics committee.

Patient and methods: 30 patients were included in each group based on power analysis. All 60 patients had the same type of knee replacement (Rotaglide rotating platform). Both groups, cemented and uncemented respectively were matched for the variables like mean age (67.2 & 67.33 years), gender (13: 17 males: females), body mass index (30.95, 29.90), average time following surgery (4 and 3.25 years), activity level (UCLA scoring: 6 & 4) and mean T score (osteoporosis index: −0.51 & −0.62). Periprosthetic bone density was measured in five regions of interest in the distal femur and five regions of interest in the proximal tibia. This was performed with Prodigy scanner (Lunar) using ‘orthopedic’ software to eliminate metal related artifacts. The same area was measured on the opposite unoperated knee. The values thus obtained were compared between the cemented and uncemented groups.

Results: There was no statistically significant difference in bone density around proximal tibia, patella and bone density proximal to femoral flange. However, there was some difference between the groups for bone density behind the flange of the femoral component measured in the lateral view, although not strictly significant at the 5% level. In this region of interest, the bone density in the cemented group appears to be less than in the uncemented group (p=0.059).

Conclusion: Use of bone cement do not seem to alter the peri prosthetic bone density contrary to suggestions in a few other studies. While reduction in periprosthetic bone density is noted in both groups, use of bone cement did not affect the results significantly.