Ectopic bone formation causing chronic pubis symphysis pain: successful management with resection and pubic fusion

Background

Chronic anterior pelvic pain affects 25% of women,1 2%–10% of men2 and may be related to a number of clinical conditions, including sports-related disorders, pregnancy-related pathologies (diastasis/instability), infection, fracture, trauma, arthritis or metastatic disease.3

Chronic pain secondary to ectopic bone formation is exceedingly rare and, unless the pathology and its impact is recognised early, can lead to chronic symptoms causing disability and functional impairment.4 We report a male patient with this entity that resulted in a 10-year disability. To the best of our knowledge, this is the only case in the literature, managed with pelvic fusion, resulting in complete resolution of symptoms and return to full activities. The addition of pelvic fusion to the ectopic bone resection may be a compelling option to be considered in such rare cases eradicating the potential of postoperative chronic instability and recurrence of the ectopic bone.

Case presentation

A man in his late 50s presented to the authors’ institution for pubic symphysis pain evaluation. The pain has been worsening during the past 10 years and was radiating from the symphysis towards the bilateral groin areas and occasionally the thighs. A few years previously, the patient had been quite active with cycling and running; however in recent years, the pain had deteriorated substantially, to the point of making the patient unable to perform any recreational activities, having also significant limitations in his ability to walk and carry out activities of daily living. Of note, there was no history of an acute traumatic event. Previous conservative treatment included physiotherapy and three injections of steroids mixed with local anaesthetic over the period of several years that provided some temporary relief. However, during the past 2 years, the pain had been increasing with further mobility restriction and a negative impact in his mental state. Physical examination demonstrated a slow gait pattern and significant localised tenderness over the pubic symphysis. There was no leg length discrepancy, no muscle wasting, no inguinal hernia and a negative FABER test (no sacroiliac joint pain on provocation testing). The lumbar spine examination was within normal limits, and he was neurovascularly intact symmetrically throughout his bilateral lower extremities.

Investigations

The patient had obtained radiographs of his pelvis when the pain had originally started, but those were negative. Seven years ago, radiographs of the pelvis were repeated and showed a calcification on the upper edge of the pubic symphysis (figure 1). Current repeat radiographs showed interval change with increasing ectopic bone formation and complete bridging over the symphysis (figure 2). Further stress imaging with ‘Flamingo’ views of the pelvis showed no instability present. A pelvic CT scan demonstrated bony hypertrophic degenerative changes with prominent posterosuperior osteophyte, loss of joint space and joint margin irregularity, and its three-dimensional reconstruction is shown in figure 3A–B. An MRI was also obtained that excluded soft tissue pathology but demonstrated inflammation of the rectus abdominis insertion. Of note, there were no signs of sacroiliac joint instability in any of the imaging modalities. Blood results, including infection and rheumatological markers, were within normal limits. Based on the above, a diagnosis of symptomatic heterotopic bone formation with associated degenerative arthritis of the symphysis pubis was established.

Treatment

The patient elected to undergo excision of the ectopic bone and pubic symphysis fusion using tricortical iliac crest bone graft and plate, as previously described.5 Briefly, under general anaesthesia, a standard Pfannenstiel incision was made. The rectus muscle at the midline was incised longitudinally and was elevated from its tendinous insertion and retracted laterally allowing adequate exposure and visualisation of the pubis symphysis. The urinary bladder was exposed and protected throughout the procedure. The exostosis was removed using an oscillating saw, and the length of the bone formation removed was 3.0 cm (figure 4A–B). Subsequently, the pubic symphysis cartilage was removed, and a tricortical bone graft taken from the right iliac crest was fashioned in a ‘T’-shape to fill the void created in the pubic symphysis and was compressed down using a 3.5 mm, six-hole Matta plate. At the end of the procedure, the rectus abdominis was repaired with 1/0 Polydioxanone (PDS) suture. The iliac crest defect from the harvested site was reconstructed with a green bone scaffold (synthetic) (Faenza, Italy).

Postoperative regimen included non-weight bearing for 10 weeks in a wheelchair, thromboprophylaxis (tinzaparin 4.500 IU) treatment for 12 weeks followed by progressive weight bearing and physical therapy. Full weight-bearing was restored at 12 weeks, and at 16 weeks, the patient was allowed to resume all types of physical activity, including jogging, swimming and cycling.

Outcome and follow-up

At 12-month follow-up, the patient was pain free, had regained his mobility and had resumed all of his desired recreational activities including cycling, swimming and jogging. His EuroQol index value6 was 0.093 versus 1000 and the EuroQuolVAS was 25/100 versus 90/100 preoperatively and postoperatively (12 month follow-up), respectively. Final imaging demonstrates complete consolidation of the pubic fusion as well as full integration of the Greenbone scaffold to the host (f igure 5).