From the Guidelines

Corticosteroids can negatively affect bone fracture healing.

Corticosteroids, such as prednisone, can cause significant bone loss and increase the risk of fractures, particularly vertebral fractures, due to their effects on trabecular bone 1.
They suppress circulating estrogen and testosterone, reducing their role in inhibiting osteoclastic activity, and also inhibit osteoblast maturation and synthetic ability 1.

Significant bone loss is caused by doses of prednisolone of 7.5 mg daily or greater in most patients, with bone loss being more rapid in the early weeks of treatment 1.
High daily and high cumulative corticosteroid doses increase the risk of fracture, particularly vertebral fracture, with a marked increase in relative risk of vertebral and hip fractures in patients receiving treatment with prednisolone ≥30 mg/day with a cumulative dose of >5 gm 1.

The use of corticosteroids can lead to a substantial risk of clinically diagnosed vertebral fracture, especially in premenopausal women ≥30 years of age receiving very high doses of corticosteroids, with a 10-year risk of 5-20% 1.
It is essential to identify patients taking corticosteroids who are at high risk of fracture and to consider preventive therapy to mitigate this risk 1.

From the Research

Corticosteroids have been shown to affect bone healing, with prolonged systemic administration causing osteoporosis and increased risk of fracture 2, 3, 4, 5.
A study using a rabbit ulnar osteotomy model found that chronic prednisone treatment inhibited bone healing, with only 3 of 20 limbs achieving radiographic union compared to 13 of 16 control limbs 3.
Another study found that corticosteroids caused significant reductions in bone mineral density at the proximal femur and lumbar spine 4.
The mechanism of corticosteroid-induced bone loss involves osteoblastic suppression and increased bone resorption, and can be influenced by factors such as smoking, excessive alcohol consumption, and hypogonadism 5.
However, a study in rats found that short-term treatment with systemic prednisone had no significant effect on bone healing, with no inhibitory effects seen after 3 days of treatment 6.

The risk of corticosteroid-induced osteoporosis can be increased by factors such as smoking, excessive alcohol consumption, and hypogonadism 5.
The initial assessment of patients starting corticosteroid therapy should include measurement of spinal bone density, urinary calcium level, and plasma calcifediol level 5.
Preventive measures such as using the lowest effective dose of corticosteroids, maintaining adequate calcium and cholecalciferol intake, and avoiding excessive alcohol consumption can help reduce the risk of bone loss 5.

Bisphosphonates, calcitonin, and cholecalciferol preparations have been shown to be effective in increasing bone density and preventing osteoporosis in patients receiving long-term corticosteroid therapy 5.
High-risk patients and those with established osteoporosis should be treated with bisphosphonates, nasal calcitonin, or calcifediol or calcitriol 5.