Study Design. Prospective study.
Objective. To determine whether or not lumbar spine surgery increases bone mineral density (BMD) of the vertebral body and/or the femoral neck, and if it is in fact related to an increase of postoperative BMD. This study was further designed to analyze the factors involved in the BMD increase.
Summary of Background Data. Long-term immobilization results in bone loss. Inactive patients who are bedridden or restricted to wheelchair mobility may have a low BMD due to immobilization. Successful lumbar spine surgery improves the activities of daily living. Thus, it might lead to an increase in BMD of the body.
Methods. Forty-seven Japanese patients, older than 60 years, who had lumbar spine surgery in the period from January to December 2009 were included. BMD of the vertebral body and the femoral neck was measured by dual-energy x-ray absorptiometry preoperatively and at 1 and 2 years after surgery, respectively. The surgical results and activities of daily living were evaluated by the Japanese Orthopaedic Association score. Walking ability was evaluated using the Nurick scale.
Results. The average preoperative BMD of the lumbar spine and the femoral neck gradually decreased postoperatively. BMD of the femoral neck in the excellent group, according to the postoperative Nurick scale, had increased at the 2-year follow-up period. There were significant differences in the percent change of BMD of both the vertebral body and the femoral neck among the groups that was categorized by the postoperative Nurick scale grades.
Conclusion. Successful lumbar spine surgery might increase BMD of the femoral neck. The percent change of BMD of both the vertebral body and the femoral neck was related to postoperative walking ability.
Level of Evidence: 3