If two bones grow together as you said, it is called fusion in professional terms, which means that the vertebral bodies are fused due to congenital or acquired factors, which is equivalent to a whole. A long-term risk after lumbar fusion is the accelerated degeneration of intervertebral discs in adjacent stages, which leads to some symptoms. So your problem may not be the two vertebral bodies, but the gap between the upper and lower vertebral bodies. It is suggested to do some MRI or CT examination to check the intervertebral disc signal or the local vertebral body bone condition, and to rule out whether it is adjacent to the vertebral body. Treatment can be functional exercise of back muscles, traction, physical therapy and wearing waistline. If the pain is severe, you can take anti-inflammatory and analgesic drugs orally. Osteoporosis? I beg to differ.