Loss of lower extremity bone mineral density 1 year after denosumab is discontinued in persons with subacute spinal cord injury

Twelve months following discontinuation of denosumab, the percent decrease in mean bone mineral density (BMD) values at the hip and knee regions were similar between both the denosumab and placebo groups. These findings emphasize the need for additional trials to understand the effect of continued administration of denosumab after subacute spinal cord injury (SCI) to avoid this demineralization.

OBJECTIVE

To determine changes in BMD 1 year after denosumab was discontinued in participants with subacute SCI who had drug treatment initiated within 90 days post SCI and continued for 1 year.

METHODS

Fourteen participants who completed a randomized, double-blinded, placebo-controlled drug trial (parent study: denosumab 60 mg (Prolia, Amgen Inc., n = 8) or placebo (n = 6); administered at baseline, 6, and 12 months) were followed 12 months after the 18 months from baseline primary end point was completed. The BMD of skeletal regions below the SCI at higher risk of fracture was measured [total hip, distal femur epiphysis (DFE), distal femur metaphysis (DFM), and proximal tibia epiphysis (PTE)] by dual energy X-ray absorptiometry.

RESULTS

The percent decreases in mean BMD values at all regions of the hip and knee from 18 to 30 months were similar in both the denosumab and placebo groups. However, at 30 months, the absolute values for mean BMD remained significantly higher in the drug treatment than that of the placebo group at the DFM (p = 0.03), DFE (p = 0.04), and PTE (p = 0.05).

CONCLUSIONS

In persons with SCI who initiated denosumab treatment during the subacute injury phase and maintained treatment for 1 year, the discontinuation of drug resulted in percent loss of mean BMD similar to that of the placebo group, with absolute mean BMD values at the knee regions at the 12-month follow-up visit significantly higher in the drug treatment than those in the placebo group. These data underscore the need to study continued administration of denosumab after subacute SCI to avoid marked demineralization in the sublesional skeleton upon discontinuation of this agent.

Generation of a Reference Dataset to Permit the Calculation of T-scores at the Distal Femur and Proximal Tibia in Persons with Spinal Cord Injury

Persons with traumatic spinal cord injury (SCI) have severe bone loss below the level of lesion with the distal femur (DF) and proximal tibia (PT) being the skeletal regions having the highest risk of fracture. While a reference areal bone mineral density (aBMD) database is available at the total hip (TH) using the combined National Health and Nutrition Examination Survey (NHANES) III study and General Electric (GE) combined (GE/NHANES) to calculate T-score (T-score_GE/NHANES), no such reference database exists for aBMD of the DF, and PT. The primary objectives of this study were (1) to create a reference dataset of young-healthy able-bodied (YHAB) persons to calculate T-score (T-score_YHAB) values at the DF and PT, (2) to explore the impact of time since injury (TSI) on relative bone loss in the DF and PT regions using the two computation models to determine T-score values, and (3) to determine agreement between T-score values for a cohort of persons with SCI using the (T-score_YHAB) and (T-score_GE/NHANES) reference datasets. A cross-sectional prospective data collection study. A Department of Veterans Affairs Medical Center and a Private Rehabilitation Hospital. A normative reference aBMD database at the DF and PT was collected in 32 male and 32 female Caucasian YHAB participants (n=64) and then applied to calculate T-score values at the DF and PT in 105 SCI participants from a historical cohort. The SCI participants were then grouped based on TSI epochs (E-I: TSI < 1y, E-II: TSI 1-5y, E-III: TSI 6-10y, E-IV: TSI 11-20y, E-V: TSI > 20y). N/A. The knee and hip aBMD values were obtained by dual energy X-ray absorptiometry (GE Lunar iDXA) using standard clinical software for proximal femur orthopedic knee software applications. There were no significant differences in mean aBMD values across the four YHAB age subgroups (21-25, 26-30, 31-35, and 36-40 yr of age) at the TH, DF, and PT; mean aBMD values were higher in men compared to the women at all skeletal regions of interest. Using the mean YHAB aBMD values to calculate T-score values at each TSI epoch for persons with SCI, T-score values decreased as a function of TSI, and they continued to decline for 11-20 yr. Moderate kappa agreement was noted between the YHAB and the GE/NHANES reference datasets for the T-score cutoff criteria accepted to diagnose osteoporosis (i.e., SD <-2.5). A homogeneous reference dataset of YHAB aBMD values at the DF and PT was applied to calculate T-score values in persons with chronic SCI. There was a moderate level of agreement at the TH between the YHAB and GE/NHANES reference datasets when applying the conventional T-score cutoff value for the diagnosis of osteoporosis.

Administration of Denosumab Preserves Bone Mineral Density at the Knee in Persons With Subacute Spinal Cord Injury: Findings From a Randomized Clinical Trial

Persons with neurologically motor-complete spinal cord injury (SCI) have a marked loss of bone mineral density (BMD) of the long bones of the lower extremities, predisposing them to fragility fractures, especially at the knee. Denosumab, a commercially available human monoclonal IgG antibody to receptor activator of nuclear factor-κB ligand (RANKL), may provide an immunopharmacological solution to the rapid progressive deterioration of sublesional bone after SCI. Twenty-six SCI participants with subacute motor-complete SCI were randomized to receive either denosumab (60 mg) or placebo at baseline (BL), 6, and 12 months. Areal bone mineral density (aBMD) by dual energy x-ray absorptiometry (DXA) at 18 months at the distal femur was the primary outcome and aBMD of the proximal tibia and hip were the secondary outcomes analyzed in 18 of the 26 participants (denosumab, n = 10 and placebo, n = 8). The metrics of peripheral QCT (pQCT) were the exploratory outcomes analyzed in a subsample of the cohort (denosumab, n = 7 and placebo n = 7). The mean aBMD (±95% CI) for the denosumab versus the placebo groups demonstrated a significant group × time interactions for the following regions of interest at BL and 18 months: distal femoral metaphysis = mean aBMD 1.187; 95% CI, 1.074 to 1.300 and mean aBMD 1.202; 95% CI, 1.074 to 1.329 versus mean aBMD 1.162; 95% CI, 0.962 to 1.362 and mean aBMD 0.961; 95% CI, 0.763 to 1.159, respectively (p < 0.001); distal femoral epiphysis = mean aBMD 1.557; 95% CI, 1.437 to 1.675 and mean aBMD 1.570; 95% CI, 1.440 to 1.700 versus mean aBMD 1.565; 95% CI, 1.434 to 1.696 and mean aBMD 1.103; 95% CI, 0.898 to 1.309, respectively (p = 0.002); and proximal tibial epiphysis = mean aBMD 1.071; 95% CI, 0.957 to 1.186 and mean aBMD 1.050; 95% CI, 0.932 to 1.168 versus mean aBMD 0.994; 95% CI, 0.879 to 1.109 and mean aBMD 0.760; 95% CI, 0.601 to 0.919, respectively (p < 0.001). Analysis of pQCT imaging revealed a continued trend toward significantly greater loss in total volumetric BMD (vBMD) and trabecular vBMD at the 4% distal tibia region, with a significant percent loss for total bone mineral content. Thus, at 18 months after acute SCI, our findings show that denosumab maintained aBMD at the knee region, the site of greatest clinical relevance in the SCI population. © 2020 The Authors. JBMR Plus published by Wiley Periodicals LLC. on behalf of American Society for Bone and Mineral Research.

A survey of protective cushion usage in individuals with spinal cord injury while traveling in a motor vehicle and on a commercial airliner

OBJECTIVE

While there are specific recommendations for pressure relieving cushions when seated in a wheelchair, there is a paucity of information regarding prescribed wheelchair cushions for persons with spinal cord injury (SCI) when traveling and not in their wheelchair seat. A questionnaire was designed to ascertain if individuals with SCI who are primarily wheelchair users utilize a prescribed wheelchair cushion when traveling in a motor vehicle (MV) or on a commercial airliner, as not utilizing one may be a causative factor in developing pressure ulcers.

DESIGN AND SETTING

Survey design in an outpatient SCI rehabilitation setting.

PARTICIPANTS

Full-time wheelchair users, with chronic (>1 year) SCI.

RESULTS

Forty-two participants completed the survey, with a mean age of 39 years old and time post-injury of 10.4 years. All subjects used a prescribed wheelchair cushion when seated in their wheelchair. Twenty-seven subjects reported transferring to a MV seat (59.5% of sample), with 25 (92.6%) reporting not using a prescribed wheelchair cushion when sitting directly on the MV seat. For subjects who traveled on an airplane (n = 23-54.8%), 19 (82.6%) reported that they do not sit on a prescribed specialty cushion.

CONCLUSION

Persons with chronic SCI, who are primary wheelchair users, utilize prescribed wheelchair cushions when sitting in their wheelchair, but most do not utilize a prescribed wheelchair cushion when seated in a MV (if they transfer out of their chair) or on a airplane seat. Studies to determine the pressures over the bony prominences on their travel surfaces may need to be undertaken to see whether the pressures are appropriate, as they may be a source of skin breakdown.