Prediction of Distal Femur and Proximal Tibia Bone Mineral Density From Total Body Dual Energy X-Ray Absorptiometry Scans in Persons with Spinal Cord Injury

Electrical stimulation paradigms on muscle quality and bone mineral density after spinal cord injury

The goal of the work was to determine the effects of altering muscle quality (peak torque and muscle CSA) via NMES-RT on bone mineral density (BMD) following application of FES-lower extremity cycling. Components of muscle quality were altered and attenuated the decline in BMD after SCI.

INTRODUCTION

Spinal cord injury (SCI) negatively impacts muscle quality and bone health. Neuromuscular electrical stimulation-resistance training (NMES-RT) has been shown to enhance muscle quality. It is unclear whether adding NMES-RT to functional electrical stimulation (FES)-lower extremity cycling may further augment muscle quality and subsequently enhance bone mineral density (BMD).

METHODS

Thirty-two participants were randomized into either 12 weeks of NMES-RT followed by 12 weeks of FES- lower extremity cycling (NMES-RT + FES; n = 16) or 12 weeks of passive movement training (PMT) followed by 12 weeks of FES-lower extremity cycling (PMT + FES; n = 16). Measurements were conducted at baseline (BL), post-interventions 1 and 2 (P1 and P2) separated evenly by 12 weeks. Left thigh muscle isometric and isokinetic torques were measured using an isokinetic dynamometer. Magnetic resonance imaging measured whole thigh and knee extensor (KE) muscle CSAs. Dual energy X-ray absorptiometry measured total and regional BMD.

RESULTS

NMES-RT elicited a trend towards greater isometric torque at 80 Hz (P = 0.057) and isokinetic torque (60 deg/s; P = 0.009 and 180 deg/s; P = 0.003) compared to PMT. Muscle CSA was greater in left whole thigh (F (2,20) = 9.1; P = 0.007) and KE (F (2,20) = 15.5; P = 0.001) by 11.0 and 8.0 cm2 respectively at P1 in the NMES-RT + FES compared to PMT + FES. In the NMES-RT + FES, ankle weights were positively associated with muscle CSA, isometric and isokinetic torques as well as muscle quality following P1. Compared to PMT + FES, NMES-RT + FES maintained BMD at the distal femur.

CONCLUSION

NMES-RT + FES enhanced muscle quality as measured by torque production and muscle CSA as result of increasing ankle weights. The addition of FES- lower extremity cycling to NMES-RT maintained but did not further augment muscle quality. Furthermore, NMES-RT + FES may help maintain BMD after SCI.

CLINICAL TRIAL REGISTRATION

Registered with clinicaltrials.gov: NCT02660073.

Bodyweight influences the relationship between serum testosterone and bone mineral density in men with spinal cord injury

STUDY DESIGN

Cross-sectional study.

OBJECTIVE

To examine the association between serum testosterone levels (T levels) and bone mineral density after spinal cord injury (SCI).

SETTING

Medical research center.

METHODS

Body composition assessments were measured in 53 men with chronic SCI. Serum T levels were measured after an overnight fast. Total and regional bone mineral density (BMD) and bone mineral content (BMC) were measured using dual-energy X-ray absorptiometry. Participants were classified into three groups based on their body weight [<65 kg, 65-80 kg, >80 kg] or serum T levels into low (400 ng/dl), mid-normal (401-544 ng/dl) and normal (>545 ng/dl) ranges.

RESULTS

Serum T level was negatively related to body weight (r = -0.33, P = 0.016), fat mass (r = -0.46, P < 0.001) and percentage fat mass (r = -0.48, P < 0.001). There were no significant relationships between serum T levels and any of the bone health measurements. Body weight was related to total, regional (P < 0.01 for both) and knee BMD (P < 0.05). T level was only related to total and regional BMD in the group with body weight of 65-80 kg.

CONCLUSION

Testosterone has no direct relationship with BMD except within a specific weight group. However, body weight or fat mass negatively influences circulating T levels in men with SCI. The relationship between serum T levels and BMD is mediated by body weight in men with SCI.

Denervation impacts muscle quality and knee bone mineral density after spinal cord injury

STUDY DESIGN

Cross-sectional study.

OBJECTIVES

To compare muscle size, body composition, bone mineral density (BMD), and metabolic profiles in denervated versus innervated individuals with spinal cord injury (SCI).

SETTING

Hunter Holmes McGuire Veterans Affairs (VA) Medical Center.

METHODS

Body composition, bone mineral density (BMD), muscle size, and metabolic parameters were collected in 16 persons with chronic SCI (n = 8 denervated, n = 8 innervated) using dual-energy x-ray absorptiometry (DXA), magnetic resonance imaging (MRI), and fasting blood samples. BMR was measured by indirect calorimetry.

RESULTS

Percent differences of the whole thigh muscle cross-sectional area (CSA; 38%), knee extensor CSA (49%), vasti CSA (49%), and rectus femoris CSA (61%) were smaller in the denervated group (p < 0.05). Leg lean mass was also lower (28%) in the denervated group (p < 0.05). Whole muscle intramuscular fat (IMF%; 15.5%), knee extensor IMF% (22%), and % fat mass (10.9%) were significantly greater in the denervated group (p < 0.05). Knee distal femur and proximal tibia BMD were lower in the denervated group, 18-22% and 17-23%; p < 0.05. Certain indices of metabolic profile were more favorable in the denervated group though were not significant.

CONCLUSIONS

SCI results in skeletal muscle atrophy and dramatic changes in body composition. Lower motor neuron (LMN) injury results in denervation of the lower extremity muscles which exacerbates atrophy. Denervated participants exhibited lower leg lean mass and muscle CSA, greater muscle IMF, and reduced knee BMD compared to innervated participants. Future research is needed to explore therapeutic treatments for the denervated muscles after SCI.

Employment of Neuromuscular Electrical Stimulation to Examine Muscle and Bone Qualities after Spinal Cord Injury

(1) Background: Resource intensive imaging tools have been employed to examine muscle and bone qualities after spinal cord injury (SCI). We tested the hypothesis that surface neuromuscular electrical stimulation (NMES) amplitude can be used to examine knee extensor muscle quality, distal femur and proximal tibia bone mineral density (BMD) in persons with SCI. (2) Methods: Seventeen persons (2 women) with chronic SCI participated in three weeks of NMES-resistance training twice weekly of 4 sets of 10 repetitions. Participants were classified according to the current amplitude (>100 mA) and the number of repetitions (>70 reps) of leg extension into greater (n = 8; 1 woman; group A) and lower (n = 9; 1 woman; group B) musculoskeletal qualities. Magnetic resonance imaging, dual energy x-ray absorptiometry, isometric peak torque, Modified Ashworth and Penn spasm frequency scales were conducted. (3) Results: In between group comparisons, current amplitude was lower (38−46%) in group A. Whole (27−32%; p = 0.02), absolute (26−33%, p = 0.02) thigh muscle and absolute knee extensor muscle cross-sectional areas (22−33%, p = 0.04) were greater in group A. Right distal femur (24%; p = 0.08) and proximal tibia (29%; p = 0.03) BMDs were lower in group B, and peak isometric torque (p < 0.01), extensor spasticity scorers (p = 0.04) and muscle spasm scores (p = 0.002) were significantly higher in group A. Regression models revealed that amplitude of current, repetitions and body weight can accurately predict musculoskeletal qualities in persons with SCI. (4) Conclusions: Surface NMES amplitude and repetitions of leg extension differentiated between SCI survivors with greater versus lower musculoskeletal qualities. The study may shed the light on the interplay between muscle and bone in persons with SCI.

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

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.