Heterotopic Ossification Leading to Ureteral Obstruction Resulting in Nephrectomy.

Heterotopic ossification (HO) is the presence of bone in soft tissue where bone normally does not exist. This can be acquired or inherited with the acquired form most often seen with either trauma, spinal cord injury, or central nervous system injury. HO most commonly affects the flexors and abductors of the hip, medial knees, and the shoulders and rarely affects the genitourinary (GU) system. We discuss a 67-year-old Caucasian male patient who presented with left-sided ureteral obstruction. He was involved in an airplane accident in 2001 resulting in a spinal cord injury. This ultimately led to heterotopic bone growth within the retroperitoneal space involving the left psoas muscle and encasing the ureter. Owing to the ureteral obstruction, a nephrectomy was performed to treat the patient's urinary symptoms. Although HO is relatively common after spinal cord injuries and trauma, it rarely infiltrates the GU system. Management ultimately involves treating the symptoms that arise because of the complications from the abnormal bone formation. For this case, because of extensive ossification resulting in obstruction of the ureter and inability to separate the kidney from the psoas, the ultimate outcome was a nephrectomy.