Retrograde Superior Pubic Ramus Screw Fixation

The retrograde superior pubic ramus screw stabilises selected anterior pelvic ring injuries as part of an overall pelvic ring reconstruction. It is a fixation strategy, not a treatment in isolation — the decision to fix the anterior ring follows from the mechanical stability of the whole injury, because the pelvic ring is a ring and an anterior lesion is rarely the only break in an unstable pattern. Indications - Displaced superior pubic ramus fractures that are unstable or part of a rotationally or vertically unstable pelvic ring pattern (lateral compression type II or III, anteroposterior compression type II or III, vertical shear)

• Parasymphyseal fractures and ramus fractures extending into the pubic root, where an intramedullary screw can bridge and stabilise the anterior column
• Tilting fractures of the pubic root in osteoporotic bone, where a medullary screw gives better purchase than a plate
• Selected symphyseal and parasymphyseal disruptions where a medullary ramus screw supplements or substitutes for symphyseal plating
• Bilateral ramus fractures with an intact posterior ring but an unstable anterior segment, particularly in the elderly
• Fragility fractures of the anterior pelvic ring in geriatric patients fit for a short percutaneous procedure but not a large open exposure Relative indications include a ramus fracture with a displaced posterior ring injury that will be fixed posteriorly (fixing the anterior ring then restores the complete ring); a patient in whom an open anterior exposure is undesirable (contaminated or severely swollen anterior soft tissues, prior Pfannenstiel surgery, obesity); and a polytrauma patient who needs only minimal additional surgical insult once already positioned supine for another procedure. Contraindications

The one decision that matters. Because every anterior fixation begins by asking the same question — can this ramus be fixed from the inside, through a percutaneous corridor, or must it be plated open? — the choice is between a retrograde intramedullary screw and open anterior plating, and the two are not mutually exclusive: a parasymphyseal fracture with symphyseal disruption may be plated at the symphysis while the ramus component is stabilised with a medullary screw.

The corridor is everything. The single most important determinant of whether a percutaneous screw can be used is whether the ramus corridor exists and will accept a screw. Preoperative CT with three-dimensional reconstruction confirms the corridor, measures its narrowest diameter and plans the trajectory. A corridor that tapers below the diameter of the smallest practical screw is a contraindication, and in osteoporotic or severely comminuted rami the medullary channel may be destroyed entirely. Consent specifically for the percutaneous anterior procedure combined with posterior ring fixation when indicated; the small but serious risk of vascular injury (external iliac, obturator, corona mortis) requiring conversion to open vascular control; screw malposition including hip joint penetration requiring revision; loss of reduction; infection; and the need for limited weight bearing and deep vein thrombosis prophylaxis after surgery.

The goal is to drive a single intramedullary cannulated screw down the medullary canal of the superior pubic ramus, from a pubic entry to the supra-acetabular ilium, entirely within bone and extra-articular to the hip, maintaining a reduction that has already been achieved. The operation is fluoroscopy-defined: the "exposure" is the multiplanar image, not a surgical incision, so confirming the four views on the awake patient and confirming the corridor on CT come first.

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Rehabilitation | Phase | Timing | Weight bearing and activity | Monitoring | |-------|--------|-----------------------------|------------| | Acute | 0 to 2 weeks | Weight bearing dictated by the overall pelvic ring injury. For an isolated stable ramus with an intact posterior ring, touch-down or partial weight bearing for the first six weeks; for an unstable pattern, restrict to the posterior injury | Chemical deep vein thrombosis prophylaxis (low-molecular-weight heparin once haemostasis secure, mechanical on the contralateral limb); paracetamol and a short opioid course, NSAIDs cautiously; early upright mobilisation with physiotherapy and a frame as needed; wound check at 10 to 14 days | | Early follow-up | 2 to 6 weeks | Progressive as pain allows | Inlet and outlet radiographs at 2 and 6 weeks to confirm maintenance of reduction | | Maturing | 6 to 12 weeks | Advance toward full weight bearing as the ring stabilises | Inlet and outlet radiographs at 12 weeks; CT only for concern about reduction, screw position or union | | Return to function | around 3 months | Manual work and sport once the ring is stable and union is progressing | Union typically by 3 months, later in osteoporotic or comminuted injuries | Return to seated desk work is usually within 2 to 3 weeks. The deep vein thrombosis prophylaxis choice and duration are individualised to the bleeding risk, because pelvic trauma carries a high venous thromboembolism risk. Special situations. In the geriatric fragility-fracture patient the goal of surgery is pain relief and mobilisation as much as radiographic union, so early mobilisation with physiotherapy and aggressive osteoporosis treatment are central to the post-operative plan, with protected weight bearing initially and a low threshold for thromboprophylaxis in the immobilised elderly. Complications

The six danger structures at a glance

Epidemiology. Low-energy fragility fractures of the anterior pelvic ring are increasingly common in the elderly, often sustained in a simple fall. A superior pubic ramus fracture may be isolated or accompanied by a contralateral ramus fracture, an ischial ramus fracture or a sacral insufficiency fracture. Persistent pain and an inability to mobilise are the typical problems that bring these patients to surgical consideration, and a displaced ramus fracture with a preserved corridor that has failed non-operative care is the setting in which a retrograde medullary screw is most useful. The superior pubic ramus corridor. The superior pubic ramus is a curved osseous strut connecting the pubic body to the acetabulum. It contains a medullary canal that runs from the pubic body, through the ramus superomedial to the acetabulum, into the dense supra-acetabular ilium — and this medullary channel is the corridor for the retrograde screw. The corridor is narrow, curved in two planes and individually variable: some patients have a generous channel that readily accepts a screw, while others have a thin, sharply curved ramus in which safe screw placement is impossible. Because it varies, preoperative CT with multiplanar and three-dimensional reconstruction is essential to measure the narrowest diameter, the curvature and the relationship to the acetabulum and hip joint, and to plan a trajectory that keeps the screw entirely within bone, extra-articular and clear of the pelvic viscera. The acetabular boundary. Laterally the corridor is bounded by the acetabulum. The screw must stay superior and medial to the acetabular dome, in the true ramus corridor, to avoid entering the hip joint. An intra-articular screw damages hyaline cartilage and may present late with hip pain or post-traumatic arthritis — the most feared silent error of the procedure, excluded on the iliac oblique view. Danger structures in detail. The corona mortis is an aberrant vascular connection between the inferior epigastric or external iliac system above and the obturator system below, crossing the superior pubic ramus around 6 cm lateral to the symphysis; it is present in a majority of hemipelves in cadaveric studies and varies from a small venous connection to a substantial arterial anastomosis, so division produces brisk bleeding from both ends of a vessel that retracts above and below the ramus. The external iliac artery and vein run along the pelvic brim on the medial border of psoas, superior and posterior to the lateral superior ramus, with the artery lateral to the vein, before passing under the inguinal ligament to become the femoral vessels. The obturator artery, vein and nerve leave the pelvis through the obturator canal inferior to the ramus; an inferior exit threatens the nerve (adductor weakness and medial thigh numbness) and the vessels. The bladder lies immediately behind the pubic symphysis and superior rami in the retropubic space, decompressed and retracted by a preoperative Foley. The spermatic cord in males and the round ligament in females pass through the superficial inguinal ring just superior and lateral to the pubic tubercle, directly above the retrograde entry. Rationale and biomechanics. Open plating of the anterior pelvic ring through a Pfannenstiel or extended ilioinguinal exposure provides strong fixation and allows direct reduction but carries the morbidity of a large anterior wound: blood loss from the corona mortis and iliac vessels, infection, hernia and wound complications. The retrograde medullary ramus screw provides stable intramedullary fixation through a percutaneous route because it lies on the neutral axis of the ramus and resists bending in the plane of greatest deformation, behaving as a load-sharing implant. Key evidence. Routt and colleagues introduced the fluoroscopically guided percutaneous retrograde medullary superior pubic ramus screw in 1995, showing that multiplanar fluoroscopy and a reducible fracture corridor are prerequisites for safe placement. Starr and colleagues (2008) found that fracture comminution, poor bone quality and residual displacement after reduction predict fixation failure, confirming that percutaneous ramus screws are effective when the corridor is intact and the reduction anatomic. The Young-Burgess classification (Burgess, 1990) provides the framework that determines which anterior ring injuries require stabilisation, Tile (1988) set out the principle that mechanically unstable pelvic ring injuries should be fixed, and Matta and Tornetta (1996) supported combined anterior and posterior internal fixation for vertically and rotationally unstable patterns.