Percutaneous Fixation of Hypertrophic Nonunion of the Inferior Pubic Ramus: A Report of Two Cases and Surgical Technique
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.
In the cases reported here, inferior ramus stabilization was combined with intramedullary fixation of the superior ramus. As each patient had deep groin pain that could not be localized to either ramus, both rami were stabilized after close assessment on preoperative CT. Solitary fixation of the superior ramus may or may not provide stability sufficient for inferior ramus union and should be performed when the OFP of the inferior ramus is unavailable.
The anatomy of the inferior ramus must be carefully reviewed before surgery, as it is seldom encountered in open and percutaneous orthopedic pelvic surgery. The inferior ramus extends from the symphysis pubis to the ischial tuberosity. The ramus is wider medially and thinner laterally near the obturator foramen. The anterior surface of the ramus is flat and concave, whereas the posterior surface is flat and convex. The anatomy of the inferior ramus varies somewhat, and any distortion (eg, fracture, nonunion) of the OFP can render it incapable of accommodating screw fixation.13
Percutaneous placement of a medullary screw in the inferior ramus requires an understanding of the fluoroscopy required. Challenges, including body habitus and unique osseous anatomy, must be recognized. Soft tissues must be protected with a drill sleeve during preparation of the screw pathway, and care must be taken to avoid placing the screw beyond the cortex of the ischial tuberosity. A prominent screw tip can irritate the patient in the hamstrings or while sitting.
Intramedullary screw fixation of the inferior ramus is a technically demanding surgical procedure. Meticulous evaluation of preoperative radiographic studies must accompany strict attention to surgical detail. A misplaced or malpositioned drill bit or screw can injure surrounding neurovascular structures. A screw that does not cross the fracture or is not in the OFP of the inferior ramus will be ineffective and
potentially dangerous.
Conclusion
We have presented a technique for percutaneous screw placement in the inferior ramus. This technique requires an understanding of the anatomy of the inferior ramus and of the intraoperative fluoroscopy required for screw placement. We have used this technique to successfully treat symptomatic hypertrophic nonunions of the inferior ramus that require skeletal stability for healing.
