Canal-to-Diaphysis Ratio as an Osteoporosis-Related Risk Factor for Hip Fractures

Prevention of osteoporosis is essential to health, quality of life, and independence in the elderly. The accepted diagnostic method for evaluation of fracture risk after osteopenia and osteoporosis is the measurement of bone mineral density with dual-energy x-ray absorptiometry (DEXA). This method is limited because of its low accessibility, high capital costs, and low sensitivity. This study evaluated whether canal diameter is a reliable indicator as a major risk factor for hip fracture in the elderly. The canal-to-diaphysis ratio was measured on plain radiographs in 38 patients with trochanteric hip fracture and compared with this ratio in 39 age-matched patients with no hip fracture. Comparison was done with the Shapiro-Wilk test and the likelihood ratio test. Measurements where taken twice with an interval of 1 week apart by the same investigator and then validated by 2 orthopedic consultants from the authors' institution to ensure inter- and intraobserver reliability. The canal-to-diaphysis ratio was significantly increased (P<.001) in patients with trochanteric hip fracture compared with control subjects without fracture. An index of 0.62 represents a risk of intertrochanteric hip fracture of 85.8%. Inter- and intraobserver reliability analysis showed very high reproducibility of the test. An inexpensive and widely accessible tool, such as evaluation of the radiographic canal-to-diaphysis ratio, can be considered as a simple method for the stratification of risk factors for hip fracture in the elderly. A cutoff is suggested to classify patients with a canal-to-diaphysis ratio of more than 0.62 who are at high risk for hip fracture.