Fracture threshold in the femur and tibia of people with spinal cord injury as determined by peripheral quantitative computed tomography

Abstract 

Eser P, Frotzler A, Zehnder Y, Denoth J. Fracture threshold in the femur and tibia of people with spinal cord injury as determined by peripheral quantitative computed tomography.

Objective

To determine bone traits of the femur and tibia with peripheral quantitative computed tomography (pQCT) that best distinguish between spinal cord injury (SCI) subjects with and without fractures.

Design

Cross-sectional study.

Setting

In- and outpatient paraplegic center in Switzerland.

Participants

Ninety-nine motor complete SCI subjects (duration of paralysis, 2mo–49y), 21 of whom had sustained fractures of the femur or tibia.

Interventions

Not applicable.

Main outcome measures

Subjects with SCI were questioned about the occurrence, location, and approximate date of fractures to their lower extremities. Trabecular and cortical bone mineral density (BMD), as well as bone geometric properties of distal epiphyses and midshafts of the femur and tibia, were measured by pQCT.

Results

Trabecular BMD of the femur and tibia distal epiphyses was found to distinguish best subjects with fractures from those without. Fractures occurred in subjects with trabecular BMD of less than 114mg/cm³ and less than 72mg/cm³ for the femoral and tibial distal epiphysis, respectively (corresponding to 46% and 29% of mean values of an able-bodied reference group). Approximately 50% of the subjects with chronic SCI (defined as time postinjury >5y for femur data and >7y for tibia data) had trabecular BMD values above the fracture threshold in the femur and about one third above the fracture threshold in the tibia.

Conclusions

By using pQCT, it may be possible to identify subjects with SCI who are at risk of sustaining fractures of the femur and tibia through minor trauma.

Key words:  Bone density , Fractures , Rehabilitation , Spinal cord injuries