Effect of growth hormone and somatomedin-C axis on fracture healing

Abstract

Aim: Many studies have examined the effects of different calciotropic hormones on fracture healing, whereas few studies focus on growth factors. Local detection of somatomedin C (IGF-1) in fracture callus, application of growth hormone (GH) and IGF-1 as non-union treatment, and low GH and IGF-1 levels in osteoporotic fractures indicate that these hormones are effective in fracture healing. However, most of these studies are based on post fracture GH and IGF-1 levels. GH and IGF-1 are also involved in acute phase response and can change due to trauma. The aim of this study is to investigate the change in GH and IGF-1 levels in patients treated with osteotomy, in which an iatrogenic fracture is created, and to evaluate the effect of these hormones on fracture healing by comparing the results before and after the fractures. Methods: Patients who were diagnosed with developmental dysplasia of the hip and underwent surgery between 2014-2015 were prospectively followed for this cohort study. Forty-one patients were included, and two groups were formed. Patients who underwent open reduction and soft tissue release without osteotomy (n=20) were included in the first group. Patients who underwent pelvic osteotomy (n=21), in which iatrogenic fractures were created, were included in the second group. Blood samples were obtained from all patients pre-operatively and on the 1st and 28th postoperative days. Friedman and Mann-Whitney U tests were used for statistical analysis. Results: Mean age of the first group, comprising 19 females (95%) and 1 male (5%), was 11.25 months (Range: 6-25 months). Mean age of the second group, including 17 females (85.7%) and 4 males (14.3%), was 74.4 months (Range: 24-120 months). While there was no significant difference between pre- and postoperative GH values in the first group (P=0.05), postoperative GH levels were significantly higher than preoperative GH levels in the second group (P<0.001). Postoperative IGF-1 levels were significantly lower than preoperative IGF-1 levels in both groups (P<0.001). When the difference of preoperative and postoperative 1st day GH and IGF-1 values were compared between two groups, GH changes were found significantly higher in the second group (P<0.001) whereas serum IGF-1 changes were significantly lower in the second group (P=0.043). Conclusion: IGF-1 is inadequate in the investigation of fracture healing due to its short half-life and local production. On the other hand, GH plays an active role in fracture healing and increases significantly in comparison to pre-fracture values. Considering the GH increase during fracture healing, it may be beneficial to support patients with pathological fracture healing with growth hormone.