Surgical technique for percutaneous retrograde medullary superior pubic ramus screw fixation of anterior pelvic ring injuries - corridor planning, multiplanar fluoroscopy, danger structures and combined ring fixation
High-yield overview
Percutaneous retrograde medullary screw fixation of the superior pubic ramus for selected anterior pelvic ring injuries | advanced
Surgical Imaging
Percutaneous retrograde superior pubic ramus screw stabilising an anterior pelvic ring injury, passed from the pubic body along the bony ramus corridor.Credit: AI-generated medical illustration · OrthoVellum
Critical Danger Structures and Exam Traps
Corona Mortis — The Silent Bleeder
The structure: an aberrant arterial and venous anastomosis between the inferior epigastric or external iliac system and the obturator system that crosses the superior pubic ramus around 6 cm lateral to the symphysis.
The risk: it lies directly in the field of the pubic entry and any anterior exposure. Division or avulsion causes brisk bleeding that is difficult to control because the vessel retracts above and below the ramus.
External Iliac Vessels — Superior Exit
The location: the external iliac artery and vein run along the pelvic brim on the medial border of psoas, just superior and posterior to the lateral superior ramus.
The risk: a guide wire or screw that exits the superior cortex of the lateral ramus can injure these vessels. The artery lies lateral to the vein. The outlet view is the safeguard that keeps the wire contained within the ramus.
Obturator Bundle and Bladder — Inferior and Posterior Exit
The obturator vessels and nerve: run in the obturator canal beneath the superior ramus. An inferior wire exit threatens the obturator artery, vein and nerve.
The bladder: lies immediately behind the pubic symphysis and superior ramus. A posterior or superior perforation from the pubis can injure it. A preoperative Foley catheter decompresses the bladder and moves it out of the corridor.
Spermatic Cord and Round Ligament — The Entry
The structure: the spermatic cord in males and the round ligament in females emerge through the superficial inguinal ring, just superior and lateral to the pubic tubercle.
The risk: the retrograde entry incision over the pubic body sits directly beneath these structures. A blind stab incision can transect them. Use a small incision and blunt dissection to the pubic body, protecting the contents of the ring superiorly.
Acetabulum and Hip Joint — Lateral Penetration
The trap: the acetabulum forms the lateral boundary of the corridor. A wire that drifts too lateral or posterior enters the hip joint or penetrates the acetabular cartilage.
The safeguard: the iliac oblique view profiles the posterior column and acetabulum and is used to confirm the screw stays extra-articular. Joint penetration may be clinically silent initially but causes early hip pain, chondral injury or sepsis if missed.
Reduction First — The Core Principle
The trap: surgeons assume the intramedullary screw will reduce the fracture as it crosses it. It will not. A screw driven across a malreduced ramus simply fixes it in a displaced position.
The fix: reduce the ramus anatomically first using closed manipulation, a percutaneous Schanz pin joystick, a pelvic reduction clamp or an external fixator. Only then advance the wire and place the screw to maintain the reduction that has been obtained.
The retrograde superior pubic ramus screw is used to stabilise 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.
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 who are fit for a short percutaneous procedure but not a large open exposure
Relative Indications
Ramus fractures with a displaced posterior ring injury that will be fixed posteriorly, where fixing the anterior ring restores the complete ring
Patients in whom an open anterior exposure is undesirable (contaminated or severely swollen anterior soft tissues, prior Pfannenstiel surgery, obese patient in whom a percutaneous route avoids a large wound)
Polytrauma patients requiring minimal additional surgical insult once positioned supine for another procedure
Contraindications
Absolute:
A destroyed or absent medullary ramus corridor (severe comminution of the ramus, large bone defects) in which a screw cannot be contained
Inability to obtain adequate multiplanar fluoroscopy
Active infection at the intended entry site
An unreduced ramus fracture that cannot be reduced closed or percutaneously and where an open reduction is therefore required
Relative:
Severe osteoporosis where screw purchase in the supra-acetabular bone is expected to be poor
Marked obesity or abundant bowel gas that degrades fluoroscopy
A very narrow ramus corridor on CT that will not accept a screw even of the smallest practical calibre
Surgeon inexperience with percutaneous pelvic fixation without intraoperative navigation support
Evidence for Percutaneous versus Open Anterior Fixation
Rationale for the Retrograde Ramus Screw
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 was introduced to provide stable intramedullary fixation of the ramus through a percutaneous route, avoiding the anterior exposure. In biomechanical terms the intramedullary screw lies on the neutral axis of the ramus and resists bending in the plane of greatest deformation, behaving as a load-sharing implant.
When Each Strategy Wins
The retrograde ramus screw is best suited to a displaced but reconstructable ramus fracture with an intact medullary corridor. Open anterior plating is preferred when the ramus is severely comminuted, when the corridor is destroyed, when an open reduction of the anterior ring is required, or when a symphyseal disruption needs formal plate fixation. The two strategies 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 is used to confirm the corridor, measure its narrowest diameter and plan the screw trajectory. A corridor that tapers below the diameter of the smallest practical screw is a contraindication.
Retrograde Ramus Screw versus Open Anterior Plating
Evidence for Combined Ring Fixation
Pelvic ring stability is a function of the whole ring. An anterior injury is rarely the only lesion in an unstable pattern: lateral compression and anteroposterior compression injuries almost always involve both the anterior and posterior ring. Fixing the anterior ring alone in a vertically or rotationally unstable injury risks late displacement. The retrograde ramus screw is therefore usually combined with posterior ring fixation — sacroiliac or iliosacral screws for sacroiliac joint and sacral injuries, and lumbopelvic fixation for highly unstable patterns. Restoration of both the anterior and posterior columns is the goal.
The Superior Pubic Ramus Corridor
The Intramedullary Channel
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. 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.
Preoperative Corridor Assessment
Because the corridor varies, preoperative CT with multiplanar and three-dimensional reconstruction is essential. The narrowest diameter of the ramus, the curvature and the relationship to the acetabulum and hip joint are assessed. A trajectory is planned that keeps the screw entirely within bone, extra-articular to the hip and clear of the pelvic viscera and vessels. The corridor diameter determines the largest screw that can be safely used.
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. The iliac oblique view profiles the posterior column and the acetabulum and is used to confirm extra-articular placement. This is the most feared silent error of the procedure: an intra-articular screw damages hyaline cartilage and may present late with hip pain or post-traumatic arthritis.
Danger Structures of the Anterior Ring
The Corona Mortis
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, though its exact morphology varies from a small venous connection to a substantial arterial anastomosis. It lies directly in the field of any anterior pelvic exposure and the retrograde entry. Injury produces brisk bleeding from both ends of the divided vessel, which retracts above and below the ramus and is difficult to control. Awareness of the corona mortis, and ligation or careful protection when an open exposure is used, is central to safe anterior pelvic surgery.
The External Iliac Vessels
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, before passing under the inguinal ligament to become the femoral vessels. The artery lies lateral to the vein. A wire or screw that exits the superior cortex of the lateral ramus threatens these vessels. The outlet view, which shows the superoinferior position of the wire, is the safeguard that keeps the implant within the ramus and below the external iliac vessels.
The Obturator Bundle
The obturator artery, vein and nerve leave the pelvis through the obturator canal, which lies inferior to the superior pubic ramus. An inferior exit of the wire or screw threatens the obturator nerve (causing adductor weakness and medial thigh numbness) and the obturator vessels. Again the outlet view is the key control: the wire must remain within the ramus and not drop into the obturator foramen.
The Bladder
The bladder lies immediately behind the pubic symphysis and the superior pubic rami, separated from them by the retropubic or prevesical space. A wire that perforates posteriorly or superiorly from the pubic body can injure the bladder. A preoperative Foley catheter decompresses the bladder, withdraws it from the posterior aspect of the symphysis and reduces the chance of injury; it also improves the radiographic appearance of the anterior ring.
The Spermatic Cord and Round Ligament
The spermatic cord in males and the round ligament in females pass through the superficial inguinal ring, which lies just superior and lateral to the pubic tubercle. The retrograde entry incision over the pubic body is directly beneath these structures. A blind stab incision can transect the cord. A small incision with blunt dissection to the pubic body, keeping the contents of the ring protected superiorly, is the safe approach.
Fluoroscopic Landmarks
Inlet View (Beam Cephalad)
The inlet view is obtained by angling the beam cephalad, approximately 45 degrees, to look down the pelvic brim. It profiles the anteroposterior or depth position of structures on the pelvic brim. For the ramus screw it is used to confirm the wire advances within the ramus in the sagittal plane, neither perforating anteriorly into the groin nor posteriorly into the pelvis. It is also the key view for monitoring reduction of the ramus because posterior displacement is best seen on the inlet.
Outlet View (Beam Caudad)
The outlet view is obtained by angling the beam caudad, approximately 45 degrees. It profiles the pubic rami and symphysis in the superoinferior plane. It is the primary view for confirming the wire stays contained within the ramus: a wire that exits superiorly threatens the external iliac vessels, and one that exits inferiorly threatens the obturator bundle. The outlet view keeps the wire centred in the ramus.
Obturator Oblique Outlet View
The obturator oblique view rolls the pelvis so the obturator foramen and anterior column are profiled. Combined with outlet angulation, the obturator oblique outlet view aligns the X-ray beam along the long axis of the superior pubic ramus, projecting the ramus as a straight corridor. This is the primary guiding view for wire advancement: it shows the full length of the intended screw path and is used to drive the wire down the centre of the ramus.
Iliac Oblique View
The iliac oblique view profiles the posterior column of the acetabulum, the posterior wall and the iliac wing. Its role in the ramus screw is to confirm the lateral end of the screw stays extra-articular: it shows the relationship of the screw to the acetabulum and hip joint. Joint penetration is confirmed or excluded on this view.
Preoperative Planning
Imaging and Corridor Confirmation
Full pelvic radiographs and a CT scan with multiplanar and three-dimensional reconstruction are mandatory. The CT is used to characterise the pattern of pelvic ring injury, to confirm the ramus corridor exists, to measure the narrowest corridor diameter and to plan the screw trajectory and length. The trajectory is rehearsed preoperatively so that the intended path keeps the screw entirely within bone, extra-articular to the hip and clear of the pelvic viscera. If the corridor is destroyed or too narrow, a percutaneous screw is not used and an open or alternative strategy is planned.
Consent
Counsel the patient specifically regarding: the need for a 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; the risk of 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.
Positioning and Preparation
Patient position: supine on a flat, fully radiolucent table. No bumps or breaks that would distort the pelvic ring are used unless required for reduction. The entire pelvis and both groins are prepared and draped to allow access to the pubic entry and, if needed, conversion to an open anterior approach or a counter-incision for reduction.
Foley catheter: inserted before prepping to decompress the bladder and move it away from the posterior aspect of the symphysis and superior rami.
Fluoroscopy setup: the C-arm is brought in from the contralateral side. Inlet, outlet, obturator oblique and iliac oblique views are obtained on the awake, unprepped patient. The ability to see all four views is confirmed before the patient is prepped and draped.
Dangers at this step
Failing to confirm that all four fluoroscopic views are obtainable before prepping, then discovering after draping that the outlet or inlet cannot be seen because of obesity or table hardware
Not inserting a Foley catheter, leaving a full bladder in the path of a posteriorly perforating wire
Positioning on a non-radiolucent element of the table that obscures the pelvic images
Reduction of the Ramus
The Principle
A retrograde ramus screw maintains a reduction that has already been achieved. It does not reduce a displaced ramus. The reduction is therefore obtained first.
Methods of Reduction
Reduction techniques include: closed manipulation by adjusting the leg and applying traction or internal or external rotation; a percutaneous Schanz pin placed into the pubic body or iliac crest as a joystick; a Jungbluth or pointed pelvic reduction forceps applied percutaneously through small stab incisions gripping the pubic body and the lateral ramus; and an anterior external fixator to close an externally rotated or diastased anterior ring. The inlet and outlet views confirm the reduction in both planes before any wire is advanced.
Clinical Pearl
Technical Tip: 'I reduce the ramus first and confirm the reduction on both the inlet and outlet views before I touch a wire. I tell my trainees that a medullary screw is a maintainer of reduction, not a reducer. If I cannot reduce the ramus closed or with a percutaneous clamp, I will not drive a screw across it in a displaced position — I convert to an open reduction.'
Retrograde Technique — Step-by-Step
Step 1: Entry Point
The entry point is on the pubic body, just lateral to the pubic symphysis, at the level of the pubic tubercle, chosen so the wire will align with the long axis of the ramus. The intended trajectory is rehearsed under fluoroscopy on the obturator oblique outlet view before any incision. A small stab incision is made over the entry point, keeping it below and medial to the superficial inguinal ring to protect the spermatic cord or round ligament. Blunt dissection is carried down to the pubic body.
Clinical Pearl
Technical Tip: 'I plan my entry point on the obturator oblique outlet view so that a line from the entry through the centre of the ramus corridor lands in the supra-acetabular ilium. Only then do I make my incision. I keep the incision below the superficial inguinal ring and bluntly dissect to the pubic body to keep the spermatic cord or round ligament out of harm's way.'
Dangers at this step
A blind stab incision that transects the spermatic cord or round ligament at the superficial inguinal ring — use a small incision and blunt dissection
An entry point that is too medial (at the symphysis) or too lateral, forcing the wire out of the corridor
Failing to rehearse the trajectory on fluoroscopy before incising
Step 2: Guide Wire Advancement
A smooth guide wire is introduced onto the pubic body and advanced under live fluoroscopy along the medullary corridor of the superior ramus. The obturator oblique outlet view is the primary guide, driving the wire down the centre of the ramus as a straight corridor. The inlet view is checked repeatedly to confirm the anteroposterior depth of the wire, and the outlet view is checked to confirm superoinferior containment. The wire is advanced toward the supra-acetabular ilium, stopping short of the sacroiliac joint. The iliac oblique view is used to confirm the lateral end of the wire remains extra-articular, clear of the acetabulum and hip joint.
Clinical Pearl
Technical Tip: 'I drive the wire under live fluoroscopy, switching between the obturator oblique outlet, inlet and outlet views. The obturator oblique outlet shows me the corridor, the inlet controls my depth, and the outlet keeps me contained in the ramus. Before I accept the final position I always look at the iliac oblique to be certain the wire has not drifted into the hip joint.'
Dangers at this step
A wire that exits the superior cortex and injures the external iliac vessels — monitor containment on the outlet view
A wire that exits inferiorly into the obturator canal, threatening the obturator bundle — monitor containment on the outlet view
A wire that drifts lateral and posterior into the acetabulum or hip joint — exclude on the iliac oblique view
Advancing the wire without confirming the ramus has been reduced first
Step 3: Confirm Position on All Views
Before any drilling, the wire position is confirmed on inlet, outlet, obturator oblique outlet and iliac oblique views. The wire must lie entirely within bone, extra-articular to the hip, with no cortical breach superiorly, inferiorly, anteriorly or posteriorly. If any view shows a breach, the wire is withdrawn and repositioned.
Step 4: Screw Measurement and Placement
The screw length is measured over the wire. The canal is drilled over the wire only if required for the chosen screw. A 7.3 mm cannulated screw is the most commonly used implant; a smaller calibre (6.5 mm) is used for a narrow corridor and a larger (8.0 mm) only if the corridor comfortably accepts it. A partially threaded screw is used when lag compression across the fracture is desired and the fracture pattern permits it; a fully threaded position screw is used when compression would shorten or displace the fragments. The screw is advanced over the wire, seating the head at the pubic body without prominence. Final fluoroscopy confirms screw position, length and the maintenance of reduction.
Clinical Pearl
Technical Tip: 'I choose the screw to fit the corridor I measured on CT, not the corridor I wish I had. I use a fully threaded position screw when the ramus is comminuted and lag compression would shorten the anterior ring. I seat the head flush at the pubic body so it is not palpable and painful later.'
Step 5: Closure and Final Imaging
The small entry wound is closed with skin sutures. Final inlet, outlet, obturator oblique and iliac oblique images are saved to document screw position, extra-articular placement and maintained reduction. A postoperative CT is obtained in complex cases or whenever joint position is uncertain, to confirm containment of the screw.
Antegrade (Supra-acetabular) Variant
When the pubic region is inaccessible because of scarring, a prior Pfannenstiel incision, a urinary diversion, a contaminated anterior wound or local soft-tissue injury, the ramus screw can be placed in an antegrade direction. The entry is made at the supra-acetabular ilium, just above the anterior inferior iliac spine, and the wire is directed anteromedially along the ramus toward the pubis. The same fluoroscopic principles apply: the obturator oblique outlet profiles the corridor, the inlet and outlet control depth and containment, and the iliac oblique excludes the hip joint. The choice between retrograde and antegrade is dictated by the anterior soft tissues and the fracture configuration.
Weight bearing is dictated by the overall pelvic ring injury. For an isolated stable ramus fracture fixed with a retrograde screw and an intact posterior ring, touch-down or partial weight bearing is typical for the first six weeks. For an unstable pattern with posterior ring fixation, weight bearing is restricted according to the posterior injury.
Deep vein thrombosis prophylaxis: pelvic trauma carries a high venous thromboembolism risk. Chemical prophylaxis (low-molecular-weight heparin) is started once haemostasis is secure, with mechanical prophylaxis on the contralateral limb. The choice and duration are individualised to the bleeding risk.
Analgesia: paracetamol and a short course of opioid as required; non-steroidal anti-inflammatory drugs used cautiously given the fracture and the bleeding risk.
Mobilisation: early upright mobilisation with physiotherapy, the aid of a frame as needed, and pulmonary toilet in the polytrauma patient.
Wound care: small percutaneous wounds dressed simply; skin sutures reviewed at 10 to 14 days.
Follow-up and Union
Radiographs: inlet and outlet views at 2, 6 and 12 weeks to confirm maintenance of reduction and progression to union.
CT: reserved for concern about reduction, screw position or union.
Union: clinical and radiographic union of a ramus fracture is typically expected by 3 months, later in osteoporotic or comminuted injuries.
Return to function: return to seated desk work within 2 to 3 weeks; return to manual work and sport once the ring is stable and union is progressing, commonly by 3 months.
Special Case: Fragility and Geriatric Ramus Fractures
Epidemiology and Pattern
Low-energy fragility fractures of the anterior pelvic ring are increasingly common in the elderly, often from 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.
When a Retrograde Screw Helps
In a geriatric patient with a displaced ramus fracture and intractable pain, a retrograde medullary ramus screw can provide rapid stability and allow mobilisation where non-operative management has failed. The medullary screw often achieves better purchase in osteoporotic ramus bone than a plate, though extremely osteoporotic bone remains a relative contraindication because of poor screw hold.
Decision-making
The decision to operate balances the benefit of stabilisation and earlier mobilisation against the risks of surgery and anaesthesia in a frail patient. A short, supine, percutaneous procedure is attractive precisely because it avoids a large exposure. The corridor is assessed on CT and a calibre and length chosen to suit. Postoperative protected weight bearing and aggressive osteoporosis treatment are part of the plan.
Special Case: Combined Anterior and Posterior Ring Fixation
The Ring Is a Ring
Most unstable pelvic injuries involve both the anterior and posterior ring. A retrograde ramus screw is therefore usually one component of a complete reconstruction. The posterior injury — a sacroiliac joint dislocation, a sacral fracture or an iliac wing fracture — is fixed with iliosacral or sacroiliac screws, lumbopelvic fixation or plating as indicated.
Sequencing
In a vertically or rotationally unstable injury the posterior ring is typically reduced and fixed first to restore the overall template, after which the anterior ring is reduced and stabilised. Fixing the anterior ring in isolation without addressing the posterior injury risks late loss of reduction. The retrograde ramus screw restores the anterior column and completes the ring.
Special Case: Obesity and the Difficult Fluoroscopic Image
The Problem
Obesity, abundant bowel gas and contrast from prior imaging all degrade pelvic fluoroscopy. The obturator oblique outlet, inlet and outlet views depend on a clear image; if they cannot be obtained, the safe percutaneous corridor cannot be confirmed and the wire cannot be confidently driven.
Intraoperative Navigation
When fluoroscopy is inadequate, intraoperative navigation (fluoroscopic navigation or CT-based navigation) offers an alternative. Navigation reconstructs the pelvis from a registered CT or a fluoroscopic sweep and tracks the wire in three dimensions, allowing placement when direct multiplanar fluoroscopy is not feasible. Navigation does not abolish the need for careful reduction and it does not change the danger structures, but it extends the percutaneous route to patients in whom fluoroscopy alone is insufficient.
Conversion to Open
If neither adequate fluoroscopy nor navigation is available, and the anterior ring must be fixed, conversion to an open anterior approach with plating is the safe alternative. A percutaneous screw driven through an uncontrolled corridor is not acceptable.
Clinical Decision Scenarios
Practise clinical reasoning and management decisions out loud
Viva scenarioAdvanced
Clinical prompt
“A 34-year-old man is involved in a high-speed motor vehicle collision. Pelvic CT shows a displaced right superior pubic ramus fracture with a right sacral fracture and anterior widening of the right sacroiliac joint — a rotationally and vertically unstable pelvic ring injury. He is now haemodynamically stable. Describe your management, with particular reference to the anterior ring.”
Practical approach
This is an unstable pelvic ring injury involving both the anterior and posterior columns. Management is staged and begins with resuscitation, proceeds to definitive reconstruction of the whole ring, and addresses the anterior ring specifically.
**Initial management**: ATLS principles. The pelvic binder is kept in place for temporary stabilisation if it was applied. A Foley catheter is inserted to decompress the bladder, monitor resuscitation and move the bladder off the posterior symphysis. Deep vein thrombosis prophylaxis is commenced once the patient is stable.
**Definitive planning**: a CT with three-dimensional reconstruction confirms the pattern and, critically, is used to confirm the right superior pubic ramus corridor exists and will accept a screw. The trajectory is rehearsed preoperatively. I confirm that the inlet, outlet, obturator oblique and iliac oblique views will be obtainable.
**Operative sequence**: the posterior ring is reduced and fixed first — iliosacral screw fixation of the sacral fracture and sacroiliac joint, restoring the overall template. The anterior ring is then addressed. The ramus is reduced first using closed manipulation and, if needed, a percutaneous clamp or joystick, confirmed on inlet and outlet views. Only once reduced do I place a retrograde medullary screw from an entry on the pubic body, driving the wire under live fluoroscopy down the corridor on the obturator oblique outlet view, with the inlet controlling depth, the outlet confirming containment, and the iliac oblique excluding the hip joint. A 7.3 mm cannulated screw of appropriate length is placed.
**Dangers I explicitly protect**: the corona mortis and external iliac vessels (superior exit), the obturator bundle (inferior exit), the bladder (posterior exit, hence the Foley), the spermatic cord at the entry, and the acetabulum and hip joint (lateral penetration, checked on the iliac oblique).
**Post-operative**: protected weight bearing dictated by the overall injury, chemical thromboprophylaxis, and inlet and outlet radiographs at 2, 6 and 12 weeks.
Viva scenarioAdvanced
Clinical prompt
“You are placing a retrograde right superior pubic ramus screw. The wire is advancing well on the obturator oblique outlet view, but on the outlet view you notice the wire has begun to drift toward the superior cortex of the lateral ramus. What is the significance, what structures are at risk, and what do you do next?”
Practical approach
A wire drifting toward the superior cortex of the lateral ramus is the warning sign of impending superior exit, which is the most dangerous direction of perforation in this procedure because the external iliac artery and vein run immediately superior and posterior to the lateral ramus along the pelvic brim. The corona mortis may also be in the field more medially.
**Significance**: the outlet view is the safeguard that keeps the wire contained within the ramus in the superoinferior plane. Loss of containment superiorly means the wire is about to leave bone and enter the zone of the external iliac vessels. This is not a position to continue advancing.
**Structures at risk**: the external iliac artery and vein, with the artery lying lateral to the vein; potentially the corona mortis more medially. Injury produces brisk, potentially exsanguinating haemorrhage that is difficult to control because the vessels are above the brim.
**What I do next**: I stop advancing immediately. I withdraw the wire back into safe bone and reassess on all four views, particularly the outlet and the inlet, to understand why the wire drifted — usually the entry point or the trajectory in the transverse plane was slightly off, or the ramus is curved and the wire has taken the wrong line. I reposition the wire to run down the centre of the ramus on the obturator oblique outlet view, confirming containment on the outlet before advancing again. I keep the C-arm on the outlet view as I approach the lateral ramus.
**If there is any haemodynamic change or sign of bleeding**: I do not withdraw the wire blindly (it may be tamponading a vessel), I alert the anaesthetist, prepare for vascular control, call vascular surgery, and convert to an open approach through an anterior incision to gain proximal and distal control of the external iliac vessels.
**Prevention**: preoperative CT corridor planning, rehearsing the trajectory, and live multiplanar fluoroscopy with the outlet view as the containment check throughout.
Viva scenarioAdvanced
Clinical prompt
“An 82-year-old woman sustained a low-energy fall three weeks ago and has a displaced left superior pubic ramus fracture. She remains in severe pain and is unable to mobilise despite analgesia and protected weight bearing. CT shows the ramus is displaced but the medullary corridor is preserved. How do you decide whether to fix this, and if so how?”
Practical approach
This is a fragility fracture of the anterior pelvic ring that has failed non-operative management: the patient is in severe pain and unable to mobilise at three weeks. In this context surgical stabilisation is reasonable, and a retrograde medullary ramus screw is well suited because it is a short, supine, percutaneous procedure that avoids a large anterior exposure in a frail patient.
**Decision-making**: I weigh the benefit of stabilisation and earlier mobilisation against the risks of surgery and anaesthesia in an 82-year-old. The fact that the medullary corridor is preserved on CT is the key enabler — it means a percutaneous screw is technically feasible. I assess bone quality on the CT; severe osteoporosis is a relative contraindication because of poor screw hold, but does not automatically preclude a medullary screw, which often grips osteoporotic ramus bone better than a plate. I confirm that the inlet, outlet, obturator oblique and iliac oblique views will be obtainable.
**Operative plan**: supine, radiolucent table, Foley catheter. The ramus is reduced first — in a geriatric, low-energy injury, closed manipulation or a percutaneous clamp often suffices, confirmed on inlet and outlet views. A retrograde medullary screw is placed from a pubic entry, driven down the corridor on the obturator oblique outlet view, with the inlet controlling depth, the outlet confirming containment, and the iliac oblique excluding the hip joint. A calibre and length chosen to suit the corridor — often a 7.3 mm or 6.5 mm screw — is used.
**Same dangers apply**: the corona mortis, external iliac and obturator vessels, the bladder, the spermatic cord or round ligament at the entry, and the acetabulum and hip joint. The patient's thinner tissues and smaller anatomy make careful blunt dissection at the entry important.
**Post-operative**: protected weight bearing initially, early mobilisation with physiotherapy, aggressive osteoporosis treatment, and deep vein thrombosis prophylaxis. The goal of surgery here is pain relief and mobilisation as much as radiographic union.
**Counselling**: I set realistic expectations — the aim is to relieve pain and get her mobilising, understanding that fixation in osteoporotic bone carries a risk of settling and that osteoporosis treatment is central to preventing further fragility fractures.
Exam day cheat sheet
Retrograde Superior Pubic Ramus Screw Fixation — exam day summary
References
Evidence
The retrograde medullary superior pubic ramus screw for the treatment of anterior pelvic ring disruptions: a new technique
