Fracture Threshold and Risk for Osteoporosis and Pathologic Fractures in Individuals with Spinal Cord Injury

The fracture threshold at the knee is a bone mineral density (BMD) of .78 gm/cm2 (−36% loss), while the breakpoint is .49 gm/cm2 (−57% loss). Using the knee as a proxy for the entire lower extremity (LE), fractures in the LE begin to occur when the BMD at the knee is .86 gm/cm2 (−25% loss) and peak at .49 gm/cm2 (−57% loss). Risk factors for fracture and osteoporosis include completeness of injury, paraplegia, body mass index (BMI) < 25 kg/m2, increasing age and duration of injury, female gender, and previous fracture. A woman with complete paraplegia and a BMI less than 25 kg/m2 is an appropriate candidate for early osteoporosis treatment.