A twenty-four-year-old man was driving a light truck at high speed when it hit a pole. He was admitted to our hospital approximately twenty-five minutes after the injury. On examination in the trauma room, the patient was in shock and had a blood pressure of 70/40 millimeters of mercury (9.33/5.33 kilopascals) and a heart rate of 140 beats per minute. He was confused and combative. The patient had multiple facial contusions; palpable bilateral fractures of the ribs; a tense, swollen abdomen; a swollen, painful right elbow; multiple lacerations of the lower extremities; blood at the urethral meatus; and a painful right hip. Radiographs confirmed that the patient had a bilateral hemopneumothorax, a fracture of the right acetabulum, and a fracture of the right radial head. The acetabular fracture involved the anterior column and extended into the iliac wing to the level of the anterior superior iliac spine (Figs. 1 and 2). A urethrogram confirmed a urethral tear, and a computerized tomography scan of the head showed cerebral contusions with small subdural hematomas in the frontal plane bilaterally. A minilaparotomy was performed, and the findings were positive.
The patient was resuscitated with use of endotracheal intubation, insertion of large-bore intravenous lines, and infusion of two liters of crystalloid fluid and was managed with bilateral tube thoracostomy, splinting of the fractures, and insertion of a suprapubic catheter into the bladder. The patient subsequently was taken to the operating room, 2.5 hours after the injury. A laparotomy revealed a colonic tear, numerous omental tears with bleeding, two large lacerations of the liver, and a rupture of the left hemidiaphragm. All of these injuries were repaired; the colonic injury was repaired primarily. The suprapubic catheter was inspected and was found to be in good position, and the dome of the bladder also was identified and was found to be normal. Because of concern about disturbing a pelvic hematoma that was noted to be present, the more caudad portion of the bladder was not exposed. The urological consultant attempted to catheterize the urethra but was not successful. Manual stressing of the iliac wings and the pelvis intraoperatively revealed vertical and rotational stability. The operation was terminated at that time because of the head injury and progressive hypothermia, and the patient subsequently was taken to the intensive-care unit.
Imaging studies performed during the next twenty-four hours included an intravenous pyelogram and a cystogram. The dome and left side of the bladder were well visualized on the cystogram, but the right side of the bladder was poorly visualized because of a small extraperitoneal rupture of the bladder (Fig. 3). A computerized tomography scan of the pelvis showed that the wall of the bladder was entrapped at the site of the fracture of the anterior column of the acetabulum (Fig. 4). On the basis of these findings, an operation was performed through an ilioinguinal approach forty-eight hours after the injury. The wall of the bladder was found to be trapped securely at the site of the acetabular fracture. A laminar spreader was used to distract the fracture of the anterior column, and an attempt was made to extract the trapped portion of the bladder. The attempt was unsuccessful, and it was evident that the femoral head was pinning the wall of the bladder against the inner aspect of the acetabulum. With traction on the lower limb, the trapped portion of the bladder was extracted easily. Examination of the wall of the bladder showed the involved area to be contused and hemorrhagic but demonstrated no evidence of full-thickness necrosis or injury. The bladder was returned to its resting position in the pelvis, and the pelvic fracture was fixed with use of a 4.5-millimeter reconstruction plate for repair of the the iliac wing and with use of interfragmentary lag-screws for repair of the acetabular fracture. The wounds were closed over suction drains, which were removed forty-eight hours after the operation. Toe-touch weight-bearing was allowed at approximately ten days postoperatively, and full weight-bearing was allowed at forty-two days postoperatively. Rehabilitation of the patient then proceeded uneventfully, and the acetabular fracture healed without complication (Fig. 5). The injury of the urinary tract was treated with staged urethral reconstruction and, at the time of the most recent follow-up examination, the patient was able to void independently with low residual volumes. Cystograms of the bladder, made six months after the injury, showed that the wall of the bladder was normal and demonstrated no evidence of rupture, stenosis, or stricture.
The soft-tissue covering and ligamentous attachments of the urinary bladder keep that structure well protected in the pelvis1-3. The anteroinferior surface of the bladder comes into contact with the symphysis pubis as well as with the superior and inferior pubic rami, and the lateral surfaces of the bladder come into contact with the inner portion of the lateral wall of the pelvis14,15. Strong layers of musculofascial tissue attach the base of the bladder to the surrounding pelvic bones. Despite this protection, injury of the bladder during pelvic trauma is common and occurs because of extreme deformation of the pelvic ring1-4. Controversy exists as to which type of pelvic fracture (anterior ring, lateral compression, or vertical shear) is most likely to be associated with injury of the bladder or the urethra7. It is well accepted, however, that most injuries of the bladder are the result of lacerations by fracture fragments or rupture of the wall of the bladder at the moment of impact. Urethral injuries most commonly result from a shearing mechanism and involve the bulbous portion of the urethra immediately caudad to the pelvic diaphragm4,9.
We postulate that the fracture of the anterior column of the acetabulum in our patient was produced by lateral compression with the hip in an externally rotated position. As the lateral wall of the pelvis was driven medially, the acetabular fracture hinged on the lateral border, opening the inner aspect of the iliac wing and the anterior column in a pincer-like fashion. This area of the fracture was in contact with the lateral wall of the bladder at the moment of most severe displacement of the lateral wall of the pelvis. With the withdrawal of the deforming force, the lateral wall of the pelvis recoiled to a resting position and the acetabular fracture partially closed, trapping a portion of the wall of the urinary bladder at the site of the fracture.
In the case of our patient, computerized tomography proved to be more accurate than cystography for determination of the nature of the injury of the bladder. The cystogram was interpreted as showing a retroperitoneal rupture of the bladder on the right side, and the importance of the extension of contrast medium toward the site of the acetabular fracture was not appreciated. The operation was performed to treat the displaced acetabular fracture and to extricate the urinary bladder. The clinical importance of entrapment of the bladder within a fracture is unclear. Such entrapment could delay the healing of the fracture or result in an intra-articular fistula, as described in a previous case report13.
Although computerized tomography of a pelvic fracture usually is performed to clarify the anatomy of the osseous injury, the case of our patient underlines the importance of a careful examination of the soft tissues in order to ensure an accurate assessment of associated injuries, especially those of the urinary tract.