Changes in total alkaline phosphatase level after hip fracture: comparison between femoral neck and trochanter fractures

Background. Biochemical bone metabolic markers are affected by fractures, and total alkaline phosphatase (ALP) is considered one of the bone formation markers. Only a few reports have dealt with changes in bone formation markers during the healing process of bone fragility hip fractures. Despite the difference in the amount of callus formation and bone fusion rate, no significant differences in longitudinal change of total ALP between femoral neck and trochanter fracture have been reported. Methods. A total of 69 osteoporotic patients with femoral neck or trochanter fracture whose serum concentrations of total ALP were examined at least four times at six periodic examination points (1, 2, 3, 4, 6, and 8 weeks after surgery) and whose state of bone union was obtained within 24 weeks after surgery were selected for this retrospective study. The characteristic longitudinal change of total ALP during the healing process was shown, and the possibility of total ALP as a predictive factor for the state of osteosynthesis of hip fractures is discussed. Results. Changes in the total ALP level according to the healing process were similar for femoral neck and trochanter fractures. The concentration of total ALP rose to a maximum at 3 weeks after surgery and then gradually decreased for both fractures. However, the range of change was significantly greater for trochanter fractures than for femoral neck fractures. For trochanter fractures, total ALP decreased from 3 to 6 weeks after surgery in all but one patient. Conclusions. Increases in the concentration of total ALP after surgery and the subsequent decreases may reflect the normal healing process. A significant difference in the changes of total ALP after surgery between femoral trochanter and neck fractures was shown. Periodic measurement of total ALP might be useful for obtaining information on the osteosynthesis state.