Cross-Sectional Study of Knee Bone Mineral Density and Fragility Fractures in Patients with Neurological Injuries and Neuromuscular Disorders

Abstract

Background: Patients with neurological injury and neuromuscular disorders are at increased risk for osteoporosis and fragility fracture. This cross-sectional study investigated whether knee bone mineral density (BMD) correlates with fragility fracture in patients with neurological injury and neuromuscular injuries.

Methodology: In this retrospective chart review, 435 participants underwent dual-energy X-ray absorptiometry (DXA) for BMD analysis. Distal femur and proximal tibial BMD measurements were performed as per the Toronto protocol. Spine, hip, and forearm DXA was performed following the standards of the International Society of Clinical Densitometry, 2019. Blinded and independent clinical evaluations and laboratory exams were performed. Participants were divided into groups with and without fracture confirmed by clinical history and radiography.

Results: Distal femur and proximal tibial BMD were measured in 288/435 (66.2%) participants. Osteoporosis was noted in 138/288 (47.9%) patients. Fractures occurred in 95/435 participants (21.8%), including one fracture in 64/435 participants (14.7%), two fractures in 24/435 participants (5.5%), and greater than two fractures in 7/435 patients (1.6%). Fractures were noted in 23/54 (42.6%) participants with post-polio syndrome, 21/66 with brain injury (31.8%), 3/10 (30%) with brain injury and spinal cord injury, 24/98 (24.5%) with neuromuscular disorders, 9/52 (17.3%) with nontraumatic spinal cord injury, and 15/155 (9.7%) with traumatic spinal cord injury. The median BMD of the knee and hip was lower in participants with fractures. Distal femur and proximal tibial BMD (odds ratio [OR] = 0.02, 95% confidence interval [CI]: 0.01-0.45) remained independently associated with fragility fracture in multivariable analysis.

Conclusion: Proximal tibial and distal femur BMD measurements offered additional information on neurological injury and neuromuscular disorders.

Keywords: Brain injury; Dual-energy X-ray absorptiometry; Fragility fracture; Neuromuscular disorders; Spinal cord injury.