Orthopedic Complications of Solid-Organ Transplantation Roy K. Aaron, MD * , Deborah McK. Ciombor, PhD Department of Orthopaedics, Brown Medical School, 100 Butler Drive, Providence, RI 02906, USA Organ transplantation has undeniably increased the longevity and quality of life of patients with end-stage organ failure. However, it has introduced the skeletal complications of (1) fragility fractures and decreased bone den- sity due to pre-transplant bone loss and immunosuppressive therapy, and (2) avascular necrosis leading to subchondral fracture and secondary osteoar- thritis. This article reviews these two skeletal complications of solid organ transplantation that lead to structural failure of bone and result in signifi- cant morbidity and reduced quality of life. Bone mineral density and fractures Measurement of bone mineral density is now the standard way of assess- ing structural bone composition with physiologic and clinical relevance. It can be accomplished with many techniques, including ultrasound, single and dual photon densitometry, quantitative CT, and dual energy X-ray ab- sorptiometry (DEXA). If cost, radiation exposure, and precision are fac- tored in, DEXA is the commonly preferred method. Three sites are typically screened: the forearm for cortical bone, the spine for trabecular bone, and the hip for a composite of cortical and trabecular bone. The Z-score compares bone mineral density to an age-, gender-, and ethnic group-matched cohort, while the T-score compares bone mineral density to peak bone mass for Caucasian females age 25 to 35. Scores are reported as mean  standard deviation. If the scores are less than 1 standard devi- ation from the mean, the bone mineral density is normal. A bone mineral density 1 to 2 standard deviations from the mean is termed osteopenia. Bone mineral density greater than 2 standard deviations from the mean is * Corresponding author. E-mail address: roy_aaron@brown.edu (R.K. Aaron). 0039-6109/06/$ - see front matter Ó 2006 Elsevier Inc. All rights reserved. doi:10.1016/j.suc.2006.06.014 surgical.theclinics.com Surg Clin N Am 86 (2006) 1237–1255