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Percutaneous Fixation of Hypertrophic Nonunion of the Inferior Pubic Ramus: A Report of Two Cases and Surgical Technique

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Symptomatic hypertrophic nonunions of the inferior pubic ramus are amenable to percutaneous screw fixation in patients with suitable osseous anatomy. Preoperative planning, knowledge of bony and surrounding soft-tissue anatomy, and understanding of intraoperative pelvic fluoroscopy are required for proper screw fixation in the medullary canal of the inferior pubic ramus.

In this article, we report 2 cases of adults with symptomatic hypertrophic nonunions of the superior and inferior pubic ramus, treated successfully with percutaneous medullary screw fixation. Percutaneous screw fixation can be used to successfully treat symptomatic hypertrophic nonunion of the inferior ramus and avoid the potential morbidity of a more extensive open surgical procedure.


 

References

Fractures of the superior and inferior pelvic rami are common in pelvic ring injuries.1 These fractures are routinely treated successfully without surgery.2 When the pelvic ring is injured, and ramus fracture or fractures represent a point of instability, surgical fixation can be performed to impart stability and reduce discomfort.3 Patients with pubic ramus fracture(s) have overall greater long-term morbidity and mortality.4 Operative stabilization of the superior pubic ramus can be achieved with open reduction and internal fixation, external fixation, and percutaneous medullary screw fixation.5-8 Inferior ramus fractures are seldom treated directly and acutely with operative reduction and fixation, as the mechanical advantage inferior ramus fixation provides is unknown.

Persistent nonunion of the pelvic ring can cause pain and disability and make reconstruction increasingly difficult.9 Open and percutaneous fixation techniques have been used to address symptomatic nonunions of the superior pubic ramus.9,10 There is limited evidence supporting surgical fixation of the inferior ramus. Open surgical fixation for symptomatic nonunions of the inferior ramus has been described.11,12 The inferior ramus has an osseous fixation pathway (OFP) amenable to percutaneous screw placement.13 Placement of a percutaneous screw in the inferior ramus requires use of preoperative computed tomography (CT) and is technically demanding. Surgeons must understand use of intraoperative fluoroscopy to ensure that the screw is contained within bone and crosses the intended zone of nonunion.

In this article, we report 2 cases of adults with symptomatic hypertrophic nonunions of the inferior ramus, treated with percutaneous screw fixation. Both patients presented with focal groin pain and activity limitations. Each had concurrent ipsilateral hypertrophic nonunions of the superior ramus, treated with percutaneous antegrade intramedullary stabilization. The patients provided written informed consent for print and electronic publication of these case reports.

Case Reports

Case 1

A 45-year-old woman fell from a horse about 8 months before presenting to the orthopedic outpatient clinic. Pelvic radiographs obtained after the fall were negative for fracture, but subsequent pelvic magnetic resonance imaging led to the diagnoses of minimally displaced left superior and inferior pubic ramus fractures and associated right-sided sacral ala fracture. The patient was treated with protected weight-bearing according to symptoms, but increasing activity-related pain and discomfort in the left groin persisted for months after injury. These symptoms were treated with analgesic medication, physical therapy, and chiropractic manipulation. Repeat imaging showed hypertrophic nonunions of the left superior and inferior pubic rami (Figure 1). Findings of the serologic testing performed for infection and metabolic deficiencies were normal at that time. The patient was referred for surgical consultation.

On evaluation, she reported constant pain in the left groin with ambulation. Specifically, squatting, pushing and pulling activities were extremely uncomfortable. She had been unable to return to work either full-time or part-time. On physical examination, she walked with an antalgic gait with a decreased stance phase of the left lower extremity. She had tenderness to palpation medial to the hip joint without evidence of hernia or lymphadenopathy. The pelvis was stable to manual compression testing.

Pelvic CT showed the nonunion site and the osteology of the inferior and superior pubic ramus of the pelvis, as well as minimal displacement and good alignment of the rami.

The patient was placed supine on a flat radiolucent table (Mizuho OSI, Union City, California). Preoperative cephalosporin antibiotics were administered. After induction of general anesthesia, the lumbosacral spine was elevated under 2 folded blankets. Arms were abducted to allow for pelvic imaging, and all bony prominences were padded. A urinary catheter was inserted aseptically to decompress the bladder. The entire abdomen and bilateral flanks were shaved, prepared, and draped in usual sterile fashion. A partially threaded cannulated screw was placed using a percutaneous antegrade technique to address the hypertrophic superior ramus nonunion.

A C-arm fluoroscopy unit (Ziehm, Orlando, Florida) was positioned on the injured side. The surgeon stood on the contralateral side. A pelvic OOOCI (outlet obturator oblique combinative image) of the symphysis pubis was obtained. This view defined the medial and lateral extents of the inferior ramus. A 0.062-in smooth Kirschner wire was used to percutaneously locate an ideal starting point on the cranial aspect of the contralateral superior pubic ramus. The starting point was adjusted on this view until an ideal intended trajectory into the contralateral (affected) inferior pubic ramus was visualized (Figure 2A).

The C-arm beam was then oriented to an “excessive” pelvic inlet view tangential to the posterior cortical surface of the affected inferior pubic ramus (Figure 2B). The tip of the wire was then adjusted to position and aim it slightly anterior to the posterior cortical surface of the affected inferior ramus. The wire was advanced into the bone about 1 cm, and the location and direction of the wire were reconfirmed as accurate.

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