Avascular Necrosis and Immunosuppression; A Management Dilemma

Despite of the fact that renal transplantation may improves the bone metabolic changes associated with end stage renal disease, yet osteoporosis and avascular osteonecrosis remain the most widely recognized osseous complications following transplantation. Head of femur is the most frequent site affected by AVN. The incidence and severity of post-transplant osseous complications is determined by underlying altered physiology such as renal hyperparathyroidism, physical inactivity, adynamic bone disease, vitamin D deficiency, hypercalcaemia, hypophosphataemia, hypomagnesaemia as well as on the type, dose and duration of immunosuppressive medications. Steroids are the major cause of osteonecrosis and osteoporosis, though other immunosuppressive medications such as calcineurin inhibitors, sirolimus and azathioprine have been shown to increase overall bone turnover leading to loss of bone density. A judicious use of steroids-avoiding immunosuppressive protocols can be beneficial; however, this approach might pose a considerable risk of allograft loss due to acute rejection and development of chronic allograft nephropathy especially if the steroid withdrawal is implemented in initial 3-6 months post-transplantation in those patients who are at a higher likelihood of developing immunological failure. Induction by cell depleting agents might help to achieve steroid-free immunosuppressive regimen in such patient