Removal of the ischium is the generally accepted method of treating ischial decubitus ulcer in patients with spinal cord injuries. Perineal urethral diverticulum has been observed in 22 of 48 patients after removal of the ischium (46 % ). It results from interference with the suspension of the triangular ligament and removal of the ischial tuberosities, thus exposing the pars diaphragmatica and the pars nuda urethrae to pressure. The diagnosis is made clinically (ischial sinus, perineal swelling, or ulcer), urethrocystographically, and urethroscopically. In the majority of cases treatment consists of introducing an indwelling catheter and of improving the general condition of the patient.
Comarr AE, Bors E. PERINEAL URETHRAL DIVERTICULUM-COMPLICATION OF REMOVAL OF ISCHIUM. JAMA. 1958;168(15):2000-2003. doi:10.1001/jama.1958.03000150042010