Serum alkaline phosphatase: A prospective biomarker for assessment of progress of fracture healing in diaphyseal fractures of long bones in adult patients

Abstract

Introduction: Serum biomarkers such as Alkaline Phosphatase can be used to assess bone-forming activity. Studies have shown that the measurement of bone formation markers such as Serum Alkaline phosphatase during the fracture healing process could enhance the accuracy of the bone healing stage assessment, allowing early detection in patients at risk of the development of delayed union or non-union. Aims: To evaluate the changes of serum alkaline phosphatase levels during healing of diaphyseal fractures of long bones in adults treated operatively. Materials and methods: A hospital based prospective study was conducted in the Department of Orthopaedics, Silchar Medical College and Hospital, Assam. 91 adult patients ranging from 18 yrs to 50 yrs with diaphyseal fractures of the tibia or femur who met the inclusion criteria were recruited in our study. Patients with systemic diseases and drugs intake which could affect the bone turnover were excluded from our study. The fractures were treated with closed reduction or open reduction and internal fixation with intramedullary nailing. The biomarker serum Alkaliine Phosphatase was measured at definite intervals until bony union was achieved clinico-radiologically. Results: Out of the 91 patients, 36 patients (Group A=normal healing group) achieved bony union by the end of 6 months. 50 patients (Group B=delayed healing group) where bony union was not completed by the end of 6 months but completed by 9 months. 5 patients (Group C=non-union group) where bony union was not seen even by the end of 9 months. At the time of admission, mean serum ALP levels remained within normal limits in all the three groups. Mean serum ALP levels followed the same pattern in Group A and Group B reaching the maximum levels at 3rd week post trauma but the mean serum ALP at every selected interval was significantly higher in Group A than Group B. In Group A, the mean serum ALP returned to baseline level by the end of 6 months, whereas, in Group B patients, the mean serum ALP remained elevated even by the end of 6 months. In group C patients, the mean serum ALP level did not rise significantly throughout the period of study. Conclusion: Thus, the determination of serum ALP levels during the fracture healing could be an additional tool to help predict fractures at risk of delayed union or non-union of diaphyseal fractures therby allowing the clinician to step in early and take appropriate intervention.