Wheelchair use and lipophilic statin medications may influence bone loss in chronic spinal cord injury: findings from the FRASCI-bone loss study

Abstract

Purpose Spinal cord injury (SCI) increases the risk of osteoporosis and low-impact fractures, particularly at the knee. However, during the chronic phase of SCI, the natural history and factors associated with longitudinal change in bone density remain poorly characterized. In this study we prospectively assessed factors associated with change in bone density over a mean of 21 months in 152 men and women with chronic SCI. Methods A mixed model procedure with repeated measures was used to assess predictors of change in bone mineral density (PROC MIXED) at the distal femur and proximal tibia. Factors with a p value of <0.10 in the univariate mixed models, as well as factors that were deemed clinically significant (gender, age, and walking status) were assessed in multivariable models. Factors with a p value of ≤0.05 were included in the final model. Results We found no association between bone loss and traditional osteoporosis risk factors, including age, gender, body composition, or vitamin D level or status (normal or deficient). In both crude and fully adjusted models, wheelchair users lost bone compared to walkers. Similarly, statin users gained bone compared to nonusers. Conclusions The statin finding is supported by reports in the general population where statin use has been associated with a reduction in bone loss and fracture risk. Our results suggest that both walking and statins may be effective osteogenic therapies to mitigate bone loss and prevent osteoporosis in chronic SCI. Our findings also suggest that loss of mechanical loading and/or neuronal factors contribute more to disuse osteoporosis that traditional osteoporosis risk factors.

Combination Therapy With Zoledronic Acid and FES‐Row Training Mitigates Bone Loss in Paralyzed Legs: Results of a Randomized Comparative Clinical Trial

“…All participants used a wheelchair as their primary mode of mobility; 75% had a motor‐complete injury. The mean BMI was 25.3 ± 5.0 kg/m; 55% of participants had normal vitamin D levels (>30 ng/mL). Nine participants were found to have a vitamin D deficiency (<30 ng/mL) and were treated with supplemental vitamin D prior to progressing in the study.…”

“…Osteoporosis following spinal cord injury (SCI) is thought to be based primarily on the loss of mechanical loading that occurs after lower extremity paralysis . Bone loss leads to fractures in up to 50% of individuals with SCI, with the majority of fractures occurring at the metaphyses of the proximal tibia and distal femur.…”

“…O steoporosis following spinal cord injury (SCI) is thought to be based primarily on the loss of mechanical loading that occurs after lower extremity paralysis. (1)(2)(3) Bone loss leads to fractures in up to 50% of individuals with SCI, with the majority of fractures occurring at the metaphyses of the proximal tibia and distal femur. Fractures are associated with prolonged immobility; worsening disability; serious medical complications, including pressure ulcer formation and amputation (4) ; and increased mortality.…”

Osteopenia in a Mouse Model of Spinal Cord Injury: Effects of Age, Sex and Motor Function

“…However, it did not improve bone mineral density [ 72 , 73 ]. A recent prospective study of factors associated with a change in bone density in chronic SCI [ 74 ], also included participants with a mean age of 55.1 ± 14.4 (SD) years (ranging from 24.7–87.1 years). Interestingly, this large study with 152 participants, found that wheelchair users lost more bone mineral density at the knee than walkers per year, an effect that was independent of age.…”

Effects of FES‐Rowing Exercise on the Time‐Dependent Changes in Bone Microarchitecture After Spinal Cord Injury: A Cross‐Sectional Investigation

“…The pathogenesis of osteoporosis after SCI is multifactorial resulting from hormonal changes, neuronal mechanisms, autonomic denervation below injury level, and to a great extent from disuse . The loss of muscle contractions and weight‐bearing results in a lack of mechanical loading and subsequent bone loss.…”