Toni Tapaninen1, Heikki Kröger, Petri Venesmaa. 1. Department of Orthopaedics and Traumatology, Kuopio University Hospital, PL 100, 70029, Kuopio, Finland, toni.tapaninen@kuh.fi.
Abstract
BACKGROUND AND PURPOSES: Insertion of a metallic implant into the femur changes bone loading conditions and results in remodeling of femoral bone. To quantify these changes in bone mineral density (BMD) after total hip arthroplasty, we monitored femoral bone with dual X-ray absorptiometry (DXA). MATERIALS AND METHODS: The periprosthetic bone mineral density was measured in seven Gruen zones at scheduled time intervals during a 10-year follow-up. A total of 38 patients went through either cemented (n = 13) or uncemented arthroplasty (n = 25). RESULTS: During the 1st post-operative year BMD decreased markedly in both groups mainly in the calcar area (Gruen zone 7); 21.9 % in the uncemented group (p < 0.005) and 26.1 % in the cemented group (p < 0.005). After that there was a slight continuous BMD loss in the proximal part of the femur and a slight increase in the distal part of femur, especially after uncemented THA. In the non-operated control side, BMD showed only a slight decrease during the follow-up (0.9 %, p = 0.003). INTERPRETATION: The study shows that when a good prosthesis-bone integration with or without cement is achieved, remodeling of the periprosthetic bone decreases after the 1st post-operative year and the bone loss reflects merely normal ageing.
BACKGROUND AND PURPOSES: Insertion of a metallic implant into the femur changes bone loading conditions and results in remodeling of femoral bone. To quantify these changes in bone mineral density (BMD) after total hip arthroplasty, we monitored femoral bone with dual X-ray absorptiometry (DXA). MATERIALS AND METHODS: The periprosthetic bone mineral density was measured in seven Gruen zones at scheduled time intervals during a 10-year follow-up. A total of 38 patients went through either cemented (n = 13) or uncemented arthroplasty (n = 25). RESULTS: During the 1st post-operative year BMD decreased markedly in both groups mainly in the calcar area (Gruen zone 7); 21.9 % in the uncemented group (p < 0.005) and 26.1 % in the cemented group (p < 0.005). After that there was a slight continuous BMD loss in the proximal part of the femur and a slight increase in the distal part of femur, especially after uncemented THA. In the non-operated control side, BMD showed only a slight decrease during the follow-up (0.9 %, p = 0.003). INTERPRETATION: The study shows that when a good prosthesis-bone integration with or without cement is achieved, remodeling of the periprosthetic bone decreases after the 1st post-operative year and the bone loss reflects merely normal ageing.