In this study, the patients with severe osteoporosis were as almost 10 times as patients without osteoporosis in suffering from DTLK after instrument-free on TLK, which is inconsistent with Yagi et al. Karikari and Metz[32] reported osteoporotic patients were at risk of developing vertebral fractures and instrumentation failure, indicating it is imperative to optimize bone health with medical therapies such as vitamin D, calcium, bisphosphonates, and parathyroid hormone. Here, PTH is linked to osteoporosis.