Locked overlapping dislocation of the pubic symphysis into the obturator foramen: a case report

INTRODUCTION

Locked dislocation of the pubic symphysis is rare and usually involves hyperabduction or hyperextension of the os coxae.1,2 We report a case of locked overlapping dislocation of the pubic symphysis, in which the pubis was locked into the obturator foramen. This may be the first report of this type of dislocation in the literature.

CASE REPORT

In July 2004, a 20-year-old man was admitted to the Government Medical College, Thiruvananthapuram, India following a road traffic accident in which he was trapped between a wall and a reversing lorry. He sustained a low-velocity side-to-side compression injury. The patient was conscious and haemodynamically stable on admission. He was unable to walk or pass urine. A Foley catheter was introduced easily and the drained urine was clear. There was no evidence of external injuries other than a small bruise over the trochanteric area. Both anterior and superior iliac spines were at the same level, and there was no limb-length discrepancy. The patient was comfortable in a supine position, and both legs could be placed flat on the bed, with no apparent deformity. He was unable to perform a straight leg raise on the right side. The hip joints were normal, with free rotation. An unexpected finding on examination was the absence of pain at the pubic symphysis and sacroiliac joints. There was no exaggeration of the hollows over the lateral aspect of the upper part of the thigh.

Radiographs of the pelvis showed an overlapping dislocation of the pubic symphysis, with no evidence of sacroiliac injury (Fig. 1). Computed tomographic scanning with 3-dimensional reconstruction revealed an overlapping dislocation of the pubic symphysis, with the right innominate bone displaced medially and posteriorly and locked into the left obturator foramen (Figs. 2 and 3). The sacroiliac joints were not involved and the bladder and other viscera were normal.

The patient underwent open reduction and internal fixation on the fifth day after admission. A modified Pfannenstiel incision was used, and the pubic symphysis exposed subperiosteally by elevating the rectus abdominis muscle. Assistance was provided by a urologist to ensure the bladder and other visceral structures remained outside the surgical field. The right pubis was found locked into the left obturator foramen after having been displaced medially and posteriorly. The pubic symphysis was reduced, though with great difficulty, by levering the locked pubic body out from the left obturator foramen. As the reduction was unstable, the pubic symphysis was fixed with 2 reconstruction plates at right angles to each other (Fig. 4). The wound was closed in layers, with reattachment of the rectus abdominis muscle. A catheter draining clear urine was left in place.

Despite a relatively uneventful early postoperative period, the patient developed a delayed wound infection, with gaping of the wound. This was treated with wound care. The plates were removed after 6 weeks and secondary suturing was completed. The pubic symphysis remained stable and the wound healed well. The patient could pass urine following removal of the Foley catheter at 6 weeks post surgery. A radiological evaluation was performed and the pubic symphysis remained reduced and stable (Figs. 5 and 6). There was no evidence of osteomyelitis, and the patient was able to ambulate. The patient subsequently developed urinary retention and underwent suprapubic catheterisation due to secondary urethral stricture. He was able to mobilise fully after 3 months. At 18 months' follow-up the patient reported that he was able to return to work and could void urine normally after urethral repair.

DISCUSSION

Eggers1 provided an extensive description of locked pubic symphysis dislocation without injury to other parts of the pelvic ring in 1952. He described 2 types of dislocation of the os coxae or hip bone-hyperabduction and hyperextension. In these types of dislocations, the affected lower extremity cannot be placed flat on the bed simultaneously with the normal side when the patient is in the supine position.

Shanmugasundaram3 reported a case of symphysis pubis dislocation similar to the present case, but without locking into the obturator foramen. The dislocation involved hyperextension, adduction and internal rotation, with posterior displacement of the pubic bones. Both lower limbs could be placed flat when the patient was lying supine. The dislocation was associated with posterior urethral injury. The pelvis was abnormal in appearance on admission and was compressed from side to side. Stable reduction of the dislocation was achieved by open reduction, without internal fixation. Urethral injury was repaired later. The patient showed radiological evidence of osteitis pubis, with secondary stricture of the urethra after 5 months, although there was no clinical evidence of osteomyelitis.

Webb4 also reported a case of overlapping dislocation of the pubic symphysis. The patient presented with tenderness at the pubic symphysis, urethral injury but no sacroiliac joint damage. A stable symphysis pubis was achieved in this case by closed reduction. The urethral injury was slow to heal and necessitated a secondary open repair, nonetheless. Long-term problems for the patient included impotence and groin pain on squatting.

Robinson et al.2 described a closed reduction of an overlapping dislocation of the symphysis pubis without urethral injury following parachuting. The injury was caused by either side-to-side compression or hyperextension. In a series, Peltier5 found the incidence of bladder or urethral injury was 10%.

CONCLUSION

Overlapping dislocation of the pubic symphysis with the pubis locked into the obturator foramen has not been previously reported. Open reduction was achieved, albeit with difficulty, and internal fixation was required, as the reduction was unstable. There was a good surgical outcome with the patient able to mobilise fully 3 months after surgery. Primary or secondary urethra! stricture is a known complication of this rare injury.

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