Introduction:
Kidney transplant recipients are prone to metabolic bone diseases and have a high risk of fractures. A high prevalence of osteoporosis (ranged 13.9% to 53% [1-5]) and osteopenia (ranged 7 % to 52.5% [3, 5-9]), leading to fractures, has been reported after kidney transplantation (KT). Although hip fractures often present with clinical signs, most vertebral fractures occur atypically [10]. Patients may benefit from radiographic screening for vertebral fractures. Vertebral fractures are often overlooked, but even undiagnosed vertebral fractures negatively affect physical function [11], quality of life [12], and mortality [13].
It has been well demonstrated that rapid bone loss occurs primarily in the first six months after KT. Following this initial period, the decrease proceeds at a slower rate or stabilizes. Approximately 2.9% to 6.8% bone loss at the spine over the first six months after kidney transplantation was detected [9, 14-16]. After the 18th month, the annual bone loss rate decreases to 1.7% [17]. Bone loss after kidney transplantation is mainly associated with glucocorticoids and other immunosuppressive drugs and previous renal osteodystrophy. Other risk factors for bone loss include hyperparathyroidism, decreased vitamin D, diabetes mellitus, post-transplant metabolic acidosis, kidney/pancreas transplantation, and the predictors of osteoporosis in the general population such as age, smoking, female gender, low body mass index (BMI). As a consequence of these factors, renal transplant recipients have shown three times increased bone fracture risk compared to age-matched controls [18, 19].
The incidence of fractures in the first five years after kidney transplantation has been reported between 8% and 45% in previous studies [4, 5, 18, 20, 21]. Bone fractures mainly occur within two years after transplantation [5]. Peripheral fractures (involving hands, ankles, feet, and femur) are detected more commonly than spinal fractures [22].
In clinical studies, there is a wide range of distribution of vertebral fracture (VF) ratios, ranged between 1.8 to 38.5 % [4, 18, 23-25], and there are conflicting results about predictors of fracture.
This descriptive clinical study aimed to determine vertebral fracture prevalence using lateral spinal radiographs and the factors associated with vertebral fractures and to evaluate bone mineral density measurements in kidney transplant recipients on a multicenter basis.