A Tibial Shaft Fracture Sustained in Childhood or Adolescence Does Not Seem to Interfere with Attainment of Peak Bone Density

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Abstract
High peak bone mass or density in early adulthood is an important protective factor against osteoporotic fractures in later life, but it is not known whether injuries on growing bones affect the attainment of peak bone mass and density. The purpose of this study was therefore to examine with dual‐energy X‐ray absorptiometry the areal bone mineral density (BMD) of the injured and uninjured extremity (the femoral neck, trochanter area of the femur, distal femur, patella, proximal tibia, and distal tibia), lumbar spine, and distal radius of young adults with a history of early life tibial shaft fracture and to find out whether the fracture had affected the attainment of peak bone density of these patients. The second objective was to clarify whether any background or clinical follow‐up variable would predict the BMD difference between the affected and unaffected extremity. Thus, the BMD and clinical status of 45 patients (34 men and 11 women), who had sustained a tibial shaft fracture in childhood or in adolescence (between 7 and 15 years of age) an average 11 years before the study, were examined. The results showed that the fracture had created a small but statistically significant injured‐to‐uninjured side BMD difference (proximal tibia −1.7%; p = 0.011, and distal tibia 2.6%; p = 0.014), while the other sites showed no significant side‐to‐side differences. There were neither significant differences in the spinal or radial BMDs between the patients and their age‐, height‐, and weight‐matched healthy controls. A further analysis of the data showed that the better the muscle strength in the injured lower limb, the lower the side‐to‐side BMD deficit in the proximal tibia of the same limb (r = 0.51; p < 0.001). Smoking had a significant association with the relative BMD in the injured distal tibia (mean injured‐to‐uninjured side BMD difference: smokers 6.1% vs. nonsmokers −0.6%, p = 0.016). Also patient's age at the time of the injury showed an association: the younger the patient at the time of the injury, the lower the side‐to‐side BMD deficit in the injured distal tibia (r = −0.35; p = 0.048). In conclusion, this study indicates that early life tibial fracture leads to a small long‐term BMD deficit in the fractured bone while the other sites of the skeleton seem not to be affected. Thus, a tibial shaft fracture sustained in childhood or adolescence seems to only marginally interfere the attainment of peak bone density, the important predictor of the osteoporotic fractures in later life.