Paraspinal muscle control in people with osteoporotic vertebral fracture

Abstract

The high risk of sustaining subsequent vertebral fractures after an initial fracture cannot be explained solely by low bone mass. Extra-osseous factors, such as neuromuscular characteristics may help to explain this clinical dilemma. Elderly women with (n = 11) and without (n = 14) osteoporotic vertebral fractures performed rapid shoulder flexion to perturb the trunk while standing on a flat and short base. Neuromuscular postural responses of the paraspinal muscles at T6 and T12, and deep lumbar multifidus at L4 were recorded using intramuscular electromyography (EMG). Both groups demonstrated bursts of EMG that were initiated either before or shortly after the onset of shoulder flexion (P < 0.05). Paraspinal and multifidus onset occurred earlier in the non-fracture group (50-0 ms before deltoid onset) compared to the fracture group (25 ms before and 25 ms after deltoid onset) in the flat base condition. In the short base condition, EMG amplitude increased significantly above baseline earlier in the non-fracture group (75-25 ms before deltoid onset) compared to the fracture group (25-0 ms before deltoid onset) at T6 and T12; yet multifidus EMG increased above baseline earlier in the fracture group (50-25 ms before deltoid) compared to the non-fracture group (25-0 ms before deltoid). Time to reach maximum amplitude was shorter in the fracture group. Hypothetically, the longer time to initiate a postural response and shorter time to reach maximum amplitude in the fracture group may indicate a neuromuscular contribution towards subsequent fracture aetiology. This response could also be an adaptive characteristic of the central nervous system to minimise vertebral loading time.

Abdominal body composition measured by quantitative computed tomography and risk of non-spine fractures: the Osteoporotic Fractures in Men (MrOS) study

“…A study by Sinaki and colleagues suggested that stronger back muscles may help in reducing vertebral fracture [39]. Another study showed that elderly women with vertebral fracture had better paraspinal muscle control than those with vertebral fracture [40]. In our study, greater total paraspinal muscle volume was weakly associated with higher non-spine fractures but this was only significant after adjusting for grip strength, fracture history and diabetes.…”

Glucocorticoid-Induced Bone Loss Is Associated with Abnormal Intravertebral Areal Bone Mineral Density Distribution

“…The lowest mean srBMD was observed in the anterior subregion (ROI 4), a result consistent with previous ex vivo histomorphometry, QCT, and DXA studies [36–40, 42, 43] and the highest was in the posterior subregion (ROI 2). This distribution pattern is probably explained by a combination of a higher cortical bone component in the posterior subregion compared to the anterior subregion and a result of changes in vertebral loading profiles, in particular intervertebral disc degeneration and changes in lumbar spine posture [21, 57]. When disc degeneration occurs, force loading increases on the neural arch, hence decreasing loading on the anterior region and causing regional demineralisation [57–59].…”

“…Vertebral fractures frequently occur spontaneously or from minor trauma [18] and are associated with morbidity including decreased physical function (e.g., balance and muscle function), loss of height, compromised pulmonary capacity, increased thoracic kyphosis, and acute and chronic back pain [6, 15, 17–21]. These sequelae become more significant with increasing numbers of vertebral fractures.…”

High risk of fall, poor physical function, and low grip strength in men with fracture—the STRAMBO study

“…Vertebral fractures were associated with low muscle strength in both sexes and lower functional reach of arms in women, not men . In women, they were associated with abnormal electromyographic activity of trunk and paraspinal muscles . However, grip strength and major fragility fractures are associated with high mortality .…”

“…15,16,67,68 In women, they were associated with abnormal electromyographic activity of trunk and paraspinal muscles. 69,70 However, grip strength and major fragility fractures are associated with high mortality. 71,72 Thus, the association between fractures and low grip strength may reflect residual confounding related to factors impairing health and bone strength and not accounted for in the model, e.g.…”