X-ray knee as a screening tool for osteoporosis

Area of Science:

• Orthopedics
• Radiology
• Osteoporosis Research

Background:

• Cortical thickness (Cor-Th) of the tibia exhibits significant variability on knee X-rays.
• Bone mineral density (BMD) is a key indicator for osteoporosis diagnosis.
• Accurate and accessible methods for preliminary BMD assessment are valuable in clinical practice.

Purpose of the Study:

• To investigate the hypothesis that tibial cortical thickness can serve as a preliminary predictor of BMD.
• To determine the correlation between tibial Cor-Th and BMD measurements at various skeletal sites.
• To identify specific tibial landmarks for optimal correlation with BMD.

Main Methods:

• Ninety-nine patients underwent digital X-ray of the left knee with an external calibration scale.
• Tibial Cor-Th was measured at five distinct levels (A-E) on the medial aspect, 5-7 cm below the tibial plateau.
• BMD was assessed using dual-energy X-ray absorptiometry (DXA) at the AP spine, left forearm, and left femur, with T-scores recorded.

Main Results:

• Significant correlations were observed between tibial Cor-Th at all measured levels and BMD at the AP spine, left femur, and left forearm (r values ranging from 0.241 to 0.426).
• The strongest correlation for AP spine BMD was at level C (r=0.347), while for left femur and forearm, it was at level B (r=0.426 and r=0.373, respectively).
• Correlation strength varied with age; significant correlations were found at all levels for individuals over 56 years old.

Conclusions:

• Medial tibial cortical thickness, particularly at 6 cm below the tibial plateau (level C), shows significant correlation with BMD.
• Tibial Cor-Th can be utilized as a preliminary screening tool to identify patients who may benefit from a confirmatory DXA scan.
• This non-invasive radiographic measurement offers a potential adjunctive method for early osteoporosis risk assessment.