Discovery w bone densitometer

The BMD of lumbar spine and left hip was measured by dual-energy X-ray absorptiometry (Hologic Discovery W Bone Densitometer, USA). All BMD measurements were performed by the same trained senior technologist and were accurately measured using acontrolled coefficient of variation 1.0CV%, accuracy 0.25%.
According to the BMD values of lumbar vertebrae (L1-L4) and left femoral neck, and referring to the Osteoporosis Committee of China Gerontological Society, it is recommended to use 2 standard deviations below the peak bone mass (−2.0SD) or 25% reduction in bone mass as the diagnostic criteria for OP in Chinese people,^{[17 ]} which were divided into the OP group (T ≤ −2.0) 399 cases and non-osteoporosis (NOP) group (T > −2.0) 274 cases.

The DXA scan (Discovery W Bone Densitometer, Hologic, Ontario, Canada) was performed by a fully trained independent operator with specialisation in body composition measurements and multiple years of experience. Players were placed in the supine position for an automatic whole-body scan. All scans were performed between 7 July 2017 and 8 July 2017.