Spondylolisthesis is a condition in which a bone in the back, called a “vertebra,” slides forward over the bone below it. This condition, affecting nearly 3 million Americans annually, most often occurs in the lumbar spine, or lower back, and can result in nerve root damage leading to back pain, numbness, weakness in the legs, or in some rare cases, loss of control over bladder and bowels. Occasionally, this condition may exhibit no symptoms at all.
MidAmerica Orthopaedics Blog
Avascular necrosis, or osteonecrosis, is a condition where bone tissue dies from lack of blood supply. Without enough blood, small breaks begin to form in the bone and potentially cause disintegration. While anyone can develop this condition, it typically occurs in middle-aged adults between the ages of thirty and sixty. If treated early enough, further bone damage can usually be minimized through home treatment and therapy; surgery is a last resort. (Mayo Clinic)