Toshiki Iwase1, Daigo Morita2, Genta Takemoto2, Hiroshi Fujita3, Naoyuki Katayama4, Hiromi Otsuka5. 1. Department of Orthopedic Surgery, Hip & Knee Reconstruction and Arthroplasty Center, Hamamatsu Medical Center, 328 Tomitsuka cyo, Naka ku, Hamamatsu, 432-8580, Japan. tossy.iwase@gmail.com. 2. Department of Orthopedic Surgery, Hip & Knee Reconstruction and Arthroplasty Center, Hamamatsu Medical Center, 328 Tomitsuka cyo, Naka ku, Hamamatsu, 432-8580, Japan. 3. Department of Orthopedic Surgery, Institute for Joint Replacement, Kyoto Katsura Hospital, Kyoto, Japan. 4. Department of Orthopedic Surgery, Hokkaido Orthopedic Memorial Hospital, Sapporo, Japan. 5. Joint Reconstruction Center, Gifu Municipal Hospital, Gifu, Japan.
Abstract
OBJECTIVE: We examined longitudinal changes in bone mineral density (BMD) around the femur for 5 years after total hip arthroplasty (THA) using cemented collarless polished double-tapered stem implantation and investigated the influence of BMD changes on radiological remodeling of the femur. MATERIALS AND METHODS: Sixty hips from 56 patients who underwent cemented THA with a collarless polished double-tapered stem were included. BMD was measured 2 weeks postoperatively (baseline), 3 months, 6 months, 1 year and annually thereafter until 5 years after surgery using dual-energy X-ray absorptiometry on the lumbar spine and proximal femur of the operated side according to the Gruen's zone classification. We analyzed predictable factors for BMD preservation in the proximal femur and compared radiological remodeling of the femur and changes in BMD. RESULTS: BMD at 5 years in zone 7 decreased less than 10%, whereas BMD in zone 1 increased to over the baseline (+ 1.9%). Multiple linear regression analyses revealed that body weight was a predictor for positive BMD change in the proximal femur. The frequency of radiolucency of the femur was significantly lower in patients who exhibited an increase in BMD at 5 years compared with BMD at 2 weeks in zone 7. CONCLUSION: BMD preservation of the proximal femur after cemented collarless polished double-tapered stem implantation was more effective in heavier patients. Furthermore, the frequency of radiolucency around the stem was significantly lower in patients who exceeded 100% of the baseline BMD in zone 7 at 5 years.
OBJECTIVE: We examined longitudinal changes in bone mineral density (BMD) around the femur for 5 years after total hip arthroplasty (THA) using cemented collarless polished double-tapered stem implantation and investigated the influence of BMD changes on radiological remodeling of the femur. MATERIALS AND METHODS: Sixty hips from 56 patients who underwent cemented THA with a collarless polished double-tapered stem were included. BMD was measured 2 weeks postoperatively (baseline), 3 months, 6 months, 1 year and annually thereafter until 5 years after surgery using dual-energy X-ray absorptiometry on the lumbar spine and proximal femur of the operated side according to the Gruen's zone classification. We analyzed predictable factors for BMD preservation in the proximal femur and compared radiological remodeling of the femur and changes in BMD. RESULTS: BMD at 5 years in zone 7 decreased less than 10%, whereas BMD in zone 1 increased to over the baseline (+ 1.9%). Multiple linear regression analyses revealed that body weight was a predictor for positive BMD change in the proximal femur. The frequency of radiolucency of the femur was significantly lower in patients who exhibited an increase in BMD at 5 years compared with BMD at 2 weeks in zone 7. CONCLUSION: BMD preservation of the proximal femur after cemented collarless polished double-tapered stem implantation was more effective in heavier patients. Furthermore, the frequency of radiolucency around the stem was significantly lower in patients who exceeded 100% of the baseline BMD in zone 7 at 5 years.
Entities:
Keywords:
Bone mineral density; Cemented collarless polished tapered stem; Dual-energy X-ray absorptiometry; Radiolucency; Total hip arthroplasty