**5.2 Secondary osteoporosis**

*Clinical Implementation of Bone Regeneration and Maintenance*

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**5. Osteoporosis**

**Figure 3.**

**5.1 Primary osteoporosis**

Osteoporosis is regarded as a silent bone disorder. Though it is silent and associated with least symptoms, it seeks the most attention. It is reported that osteoporosis targets every third woman and every fifth man beyond 50 years of their ages [44]. Osteoporosis is a pathological condition in which bone mineral density is severely diminished with weakened bone microarchitecture [45]. Bones at the areas specific to hip, wrist and spine are highly vulnerable for the osteoporotic fractures. The occurrence ratio in female to male for the osteoporosis is 1:6 with 61% of fractures befalling in the women [46]. Besides, postmenopausal women have a greater tendency towards osteoporosis [47]. It is predicted that there would be around 6 million victims having osteoporosis by the year 2050 [48]. Osteoporosis is

*RANKL-RANK signaling pathway in the osteoclasts. RANKL (present on the surface of osteoblasts) interacts with RANK receptor (on the surface of osteoclasts). RANK does not possess any kinase activity and hence recruits TRAF proteins to the cytoplasmic region of the receptor. This further transduces the signal to downstream components and activates. (1) TAK1 (member of mitogen activated kinase family, MAPK), promotes the ERK dependent activation of NFATc1. (2) NFK-β, after the phosphorylation based degradation of inhibitor of NFK-β (IKβ). (3) Other downstream proteins viz. JNK that leads to transcriptional activation* 

Primary osteoporosis is the most usual type of osteoporosis. It has two subcategories: Type-I osteoporosis/postmenopausal osteoporosis, is a well-recognized bone issue in the postmenopausal women that is chiefly instigated by estrogen deficit due to menopause, while type-II osteoporosis/age-related osteoporosis is mainly caused as a result of aging in women and men both [49]. In Type-I primary

categorized into two major types mentioned as follows:

*of NFATc1 and additional factors resulting in the osteoclastogenesis.*

Bone disorders which are secondary impediments of other health-related issues, e.g., adverse effects of drugs interventions, fluctuations in the cycle of physical activities, etc. are acknowledged under the category of secondary Osteoporosis [49]. Glucocorticosteroids and anticonvulsant-based interventions are majorly reported in the cases of secondary osteoporosis [55]. Several other disorders, e.g., endocrinopathies, which have the tendency to reduce the bone mass and interfere with normal bone formation, are also capable of inducing secondary osteoporosis. This form of osteoporosis is found in both pre/post- menopausal women and men [55].
