Neurogenic,
heterotopic ossification is characterised by the formation of new, extraosseous (ectopic) bone in soft tissue in patients with
neurological disorders. A 33-year-old female, who was born with
spina bifida,
paraplegia, and diastasis of symphysis pubis, had indwelling
urethral catheter drainage and was using
oxybutynin bladder instillations. She was prescribed
diuretic for swelling of feet, which aggravated bypassing of
catheter. Hence,
suprapubic cystostomy was performed. Despite
anticholinergic therapy, there was chronic urine leak around the suprapubic
catheter and per urethra. Therefore, the urethra was mobilised and closed. After closure of the urethra, there was no urine leak from the urethra, but urine leak persisted around the suprapubic
catheter. Cystogram confirmed the presence of a Foley balloon inside the bladder; there was no
urinary fistula. The Foley balloon ruptured frequently, leading to extrusion of the Foley
catheter. X-ray of abdomen showed heterotopic bone formation bridging the gap across diastasis of symphysis pubis. CT of pelvis revealed heterotopic bone lying in close proximity to the balloon of the Foley
catheter; the sharp edge of heterotopic bone probably acted like a saw and led to frequent
rupture of the balloon of the Foley
catheter. Unique features of this case are: (1) temporal relationship of heterotopic bone formation to
suprapubic cystostomy and chronic urine leak; (2) occurrence of
heterotopic ossification in pubic region; (3) complications of heterotopic bone formation viz. frequent
rupture of the balloon of the Foley
catheter by the irregular margin of heterotopic bone and difficulty in insertion of suprapubic
catheter because the heterotopic bone encroached on the suprapubic track; (4)
synostosis between pubic bones as a result of
heterotopic ossification.. Common aetiological factors for neurogenic,
heterotopic ossification, such as forceful manipulation,
trauma, or spasticity, were absent in this patient. Since heterotopic bone formation was observed in the pubic region after
suprapubic cystostomy and chronic urine leak, it is possible that risk factors related to the urinary tract might have played a role in heterotopic bone formation, which resulted in
synostosis between pubic bones.