Symphysis Pubis Plating (Anterior Pelvic Ring ORIF)

Surgical Indications

Absolute Indications

• Symphyseal diastasis greater than 2.5 cm on AP pelvis radiograph with clinical or radiographic evidence of pelvic ring instability (open-book / APC-II or APC-III pattern)
• Combined anterior and posterior pelvic ring injury requiring anterior stabilisation to restore pelvic ring continuity
• Open pelvic injury with symphyseal disruption requiring debridement and stabilisation
• Associated bladder or urethral injury requiring simultaneous repair and symphyseal stabilisation

Relative Indications

• Diastasis 1.5-2.5 cm with persistent pain or instability after non-operative management with a pelvic binder
• Young patient with high functional demand and residual symphyseal pain after conservative treatment
• Polytrauma patient in whom early mobilisation is critical and anterior plating facilitates nursing and respiratory care

Contraindications

Absolute:

• Haemodynamic instability requiring damage-control external fixation only (convert later)
• Active pelvic or abdominal infection
• Severe osteoporosis or bone loss precluding stable screw purchase (consider external fixation or alternative fixation)

Relative:

• Patient too unstable for prolonged prone or supine positioning
• Pregnancy (second or third trimester) — consider external fixation until delivery
• Pre-existing severe abdominal wall hernia or prior Pfannenstiel incision with extensive scarring

Evidence for Anterior Plating

Biomechanical and Clinical Outcomes

• Anterior symphyseal plating restores greater than 80 percent of native pelvic ring stiffness when the posterior ring is stable or simultaneously fixed.
• Single superior plate with three screws on each side provides adequate stability for APC-II injuries; double plating (superior plus anterior) is reserved for APC-III or osteoporotic bone.
• Implant failure rates range from 5-15 percent when posterior ring instability is not addressed; failure drops below 5 percent with concurrent posterior stabilisation.

Posterior Ring Stabilisation is Mandatory

Multiple series demonstrate that isolated anterior plating in the presence of posterior ring injury leads to early plate breakage or screw loosening in up to 30 percent of cases. Simultaneous or staged posterior fixation (percutaneous SI screws preferred) is the standard of care for APC-III and combined injuries.

Corona Mortis Awareness

Anatomic studies report corona mortis in 20-40 percent of specimens. Intraoperative identification and ligation prevents the most common cause of life-threatening bleeding during anterior pelvic surgery. Routine exposure of the superior ramus under direct vision is recommended.

Relevant Surgical Anatomy

Pubic Symphysis

• Fibrocartilaginous joint between the medial ends of the pubic bones
• Superior and inferior pubic ligaments, anterior and posterior ligaments provide stability
• The symphyseal disc is 3-5 mm thick in adults and is not violated during plating
• The pubic tubercles are the key landmarks for rectus insertion and plate placement

Corona Mortis

• Anomalous vascular anastomosis present in 20-30 percent of patients
• Usually arises from the inferior epigastric or external iliac artery and crosses the superior pubic ramus 5-7 cm lateral to the symphysis
• Drains into the obturator vein or directly into the external iliac vein
• Must be identified, ligated, or protected before superior ramus retraction or screw placement

Space of Retzius

• Extraperitoneal space between the pubic symphysis and the bladder
• Accessed by developing the plane between the rectus abdominis and the transversalis fascia
• The bladder lies immediately posterior to the symphysis — always decompressed and protected with a malleable retractor

Rectus Abdominis Insertion

• Inserts on the superior aspect of the pubic tubercle and the anterior surface of the pubic body
• Must be elevated sharply for symphyseal exposure
• Reattachment at closure prevents abdominal wall hernia and maintains core stability

Spermatic Cord and Round Ligament

• Cross the inguinal canal immediately lateral to the pubic tubercle
• Protected by identifying the cord structures and retracting them laterally during lateral ramus exposure

Obturator Nerve and Vessels

• Exit the pelvis through the obturator canal 2-3 cm lateral to the symphysis
• At risk during lateral superior ramus dissection and screw placement in the superior ramus

Positioning and Preparation

Patient position: Supine on a radiolucent table. Both arms abducted 90 degrees or tucked. A small bump under the sacrum improves access to the symphysis. The table must allow full inlet, outlet, and Judet views.

Anaesthesia: General endotracheal anaesthesia with muscle relaxation. Consider epidural for postoperative analgesia in isolated injuries.

Preparation: Wide skin prep from xiphisternum to mid-thigh including the perineum. Insert a Foley catheter before incision and confirm bladder decompression. Have a vascular set and blood products available. Intraoperative cell salvage is useful for major pelvic bleeding.

Fluoroscopy: Confirm that inlet, outlet, and AP views are obtainable before draping. A radiolucent table and positioning that allows C-arm access from both sides is essential.

Pfannenstiel Approach — Step-by-Step

Step 1: Incision and Exposure

Make a transverse Pfannenstiel incision 2 cm above the pubic symphysis, extending 8-12 cm laterally. Divide the subcutaneous fat and identify the linea alba. Incise the linea alba in the midline and develop the space of Retzius bluntly. Place a self-retaining retractor (Bookwalter or Omni-Tract) with blades on the rectus edges.

Step 2: Elevation of Rectus Insertions and Identification of Corona Mortis

Elevate the rectus abdominis insertions sharply from the superior aspect of the pubic tubercles using electrocautery or a periosteal elevator. Tag each insertion with a heavy non-absorbable suture for later repair. Continue subperiosteal elevation laterally along the superior pubic ramus for 6-8 cm on each side.

Identify the corona mortis during lateral ramus exposure. If present, ligate it with vascular clips or ties before proceeding with reduction.

Step 3: Reduction of the Symphysis

Apply pointed reduction clamps or a Weber clamp to the pubic tubercles. Reduce the diastasis under direct vision while monitoring the reduction with fluoroscopy (AP, inlet, outlet). In chronic or severely displaced injuries, a Schanz pin in each iliac crest can be used as a joystick to control rotation.

Once reduced, maintain the reduction with a pointed clamp or provisional K-wire.

Step 4: Plate Application and Fixation

Select a 6- or 8-hole 3.5 mm or 4.5 mm reconstruction plate. Contour the plate to fit the superior surface of the symphysis. Place the plate slightly anterior to the midline to avoid the symphyseal disc. Insert three bicortical screws on each side, avoiding penetration into the bladder or the symphyseal disc.

In osteoporotic bone or highly comminuted injuries, consider a second anterior plate (3.5 mm) placed on the anterior surface of the symphysis for added stability.

Step 5: Closure and Posterior Ring Stabilisation

Irrigate the wound. Reattach the rectus insertions to the plate or bone with heavy non-absorbable sutures. Close the linea alba in two layers. Close subcutaneous tissue and skin. Apply a sterile dressing.

If posterior ring instability was identified, perform percutaneous SI screw fixation (or posterior plating) in the same sitting or as a staged procedure once the patient is physiologically stable.

Post-operative Protocol

Immediate Phase (Day 0-7)

• Mobilisation: Bed to chair on day 1 with assistance. Touch-down weight-bearing on the affected side if unilateral injury; bilateral weight-bearing as tolerated if posterior ring stable.
• DVT prophylaxis: Low-molecular-weight heparin from day 1 until mobile or discharged.
• Bladder management: Continue Foley catheter for 48-72 hours; remove once urine output stable and patient can void. Monitor for urinary retention.
• Wound care: Daily inspection. Remove drains (if used) at 48 hours.
• Analgesia: Multimodal — paracetamol, NSAIDs (if renal function allows), opioids as needed, regional catheter if placed.

Early Phase (Week 1-6)

• Weight-bearing: Touch-down or partial weight-bearing (20 kg) for 6 weeks if posterior ring was unstable. Progress to full weight-bearing at 6-12 weeks once radiographs confirm stability.
• Hip precautions: Avoid hip flexion greater than 90 degrees and adduction for 6 weeks to protect the repair.
• Physiotherapy: Isometric quadriceps and gluteal exercises from day 1. Gentle hip range-of-motion exercises from week 2. Core stability and pelvic floor exercises from week 4.
• Follow-up imaging: AP, inlet, and outlet pelvis radiographs at 2, 6, and 12 weeks.

Late Phase (Week 6-12+)

• Full weight-bearing: Begin at 6-12 weeks once posterior ring union is progressing.
• Return to activity: Low-impact activities at 3 months; running and sports at 6 months if asymptomatic and radiographically united.
• Hardware removal: Considered at 12-18 months if symptomatic (plate prominence, pain); not routine.

Rehabilitation Milestones

• Week 2: Independent transfers, touch-down weight-bearing with frame.
• Week 6: Partial weight-bearing with crutches; hip ROM 0-90 degrees.
• Week 12: Full weight-bearing; return to light work.
• Month 6: Full activities if united and pain-free.