Journal of Osteoporosis and Physical Activity
Open Access

Principles in Pathophysiology of Bone Loss in Disuse Osteoporosis

Furukawa Yuto^{* *}Correspondence: Furukawa Yuto, Department of Orthopaedic Surgery, Shinshu University School of Medicine, Nagano, Japan, Email:

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Osteoporosis is the condition wherein a low bone mass and modified microarchitecture of the bone prompts risk of fracture. Generally, osteoporosis has been classified into primary and secondary osteoporosis. Primary osteoporosis refers to osteoporotic conditions which are not connected with other chronic illnesses and is generally connected with aging and decreased gonadal capability, like decreased level of estrogen, though secondary osteoporosis is the sort of osteoporosis caused by other medical issues. Although there are numerous viable treatments accessible for primary osteoporosis, there is an absence of effective treatments for disuse osteoporosis. Disuse bone loss overall is a decrease of bone mass comparable to bone volume, while the proportion of bone mineral to collagen remains unchanged. The deficiency of trabecular bone is more rapid and dramatic, while the cortical loss goes on for a longer period. Bones of lower limbs are exposed to mechanical stimulations during day to day life given by static gravity-related weight-bearing, ground reaction forces, and dynamic loading produced by muscle contractions during locomotion.

Long term bed rest brings about the absence of ground force reaction and decrease of muscle contractions. Rittweger have done a 35 days bed rest trial and surveyed bone density fourteen days after the bed rest. They announced decrease of bone mass in the cancellous bone-rich area, 1% at distal femur, 3% at patella, and 2% at distal tibia while no progressions in distal radius. A similar group has seen that bone mass in distal radius stayed unchanged after 56 days and 90 days bed rest, while bone mass in distal tibia declined 3.7% and 6% correspondingly. The reductions of cortical bone thickness and density were lower than 2% after up to 90 days bed rest. These outcomes propose that long-term bed rest doesn't influence equilibrium of bone metabolism very much. Disuse osteoporosis comprises the decrease of bone mass after Spinal Cord Injury (SCI) and other cerebrum neurologic circumstances also. SCI prompts significant decrease in ground force reaction and muscle compression in the lower limbs bringing about dramatic reduction in bone mass.

Consequence of a cross-sectional review conveyed by Garland et al. demonstrated over 20% bone loss at distal femur 3 months after injury in posttraumatic paraplegic and quadriplegic SCI patients. Beside of SCI, lower limb removal, obtained brain injury, and other neurologic conditions can also lead to disorders which, thus, bring about disuse osteoporosis. A new cross-sectional study showed that 42.5% and 23.6% of disabled patients after neurologic injuries, like SCI or different conditions for somewhere around 90 days, had created osteopenia and osteoporosis. Exposure to microgravity would prompt reduced weight-bearing and ground reaction forces that results in decrease in bone mass. In correlation of the three reasons for disuse osteoporosis, or at least, long term bed rest, paralysis, and microgravity, every one of them include the decrease of ground reaction forces and weight-bearing activities. Nonetheless, patients with long term bed rest or paralysis are additionally exposed to decreased or even absence of muscular contraction.

Osteoporosis is a multifactorial skeletal disorder that can be connected with different risk factors. Physical disability, propelling age and exposure to microgravity increase the risk of suffering from osteoporosis, and such disuse osteoporosis is related with tremendous financial and wellbeing trouble. Understanding the pathology and the underlying mechanisms of disuse osteoporosis is significant for the advancement of new procedures on drugs or treatment protocols for preventing or decreasing disuse osteoporosis. Certainly, the whole picture of the pathophysiology of disuse osteoporosis is as yet unclear, however further examinations on activity component of hormones, for example, IGF-I and sclerostin would give bits of knowledge on prospective research works.