High Yield Overview

MODIFIED STOPPA - INTRAPELVIC QUADRILATERAL ACCESS

Midline Approach | Quadrilateral Surface | Suprapubic Window

Critical Modified Stoppa Approach Exam Points

Space of Retzius

Retropubic space between bladder anteriorly and pubic symphysis posteriorly. This avascular plane is the key to the approach - develop it bluntly to access the medial pelvic wall without entering peritoneum or damaging bladder.

Quadrilateral Surface Access

The modified Stoppa provides superior access to quadrilateral surface compared to ilioinguinal medial window. Direct visualization allows placement of buttress plates to prevent medial subluxation of femoral head.

Bladder Mobilization

Mobilize bladder posterolaterally off the quadrilateral surface. This is the key maneuver - gentle blunt dissection in correct plane. Foley catheter essential to decompress bladder and reduce injury risk.

Corona Mortis Again

Just as in ilioinguinal approach, corona mortis is encountered crossing superior pubic ramus. Must identify and ligate before proceeding laterally. Same 10-30% incidence and hemorrhage risk.

Modified Stoppa vs Ilioinguinal - Decision Making

Mnemonic

STOPPASTOPPA - Key Steps of Approach

Memory Hook:STOPPA reminds you of the systematic steps to safely access the quadrilateral surface intrapelvically

Mnemonic

RETZIUSRETZIUS - Anatomical Boundaries

Memory Hook:RETZIUS describes the space of Retzius anatomy - the key surgical corridor for modified Stoppa

Mnemonic

CORONACORONA - Vascular Management (Same as Ilioinguinal)

Memory Hook:CORONA mortis is the 'crown of death' - must ligate it in both Stoppa and ilioinguinal approaches

Overview and Historical Context

The modified Stoppa approach was adapted from the Stoppa hernia repair technique and popularized for acetabular fractures by Cole and Bolhofner in the 1990s. It provides intrapelvic access to the quadrilateral surface and medial acetabular structures.

Historical evolution:

Original Stoppa: Developed for inguinal hernia repair using retropubic space
Cole and Bolhofner (1994): Applied to acetabular fracture surgery
Sagi et al (2000s): Refined technique and indications
Current: Increasingly preferred for quadrilateral surface access

Why it gained popularity:

Superior quadrilateral surface visualization vs ilioinguinal medial window
Lower nerve injury risk (no lateral femoral cutaneous nerve at risk)
Better cosmetic result (Pfannenstiel incision)
Combines well with other approaches

Stoppa vs Ilioinguinal for Quadrilateral

The modified Stoppa approach provides superior access to the quadrilateral surface compared to the medial window of the ilioinguinal approach. Working intrapelvically allows direct visualization and plate application to prevent medial subluxation. However, Stoppa cannot access the iliac wing or high anterior column - these still require ilioinguinal lateral/middle windows.

Current indications:

Isolated quadrilateral surface fractures
Associated both-column fractures (with medial displacement)
T-type fractures (anterior component)
Low anterior column with quadrilateral involvement
Often combined with lateral window ilioinguinal or separate lateral incision

Anatomy - Space of Retzius

The space of Retzius is the key anatomical space - a potential extraperitoneal space between the bladder and the posterior surface of the pubic symphysis.

Boundaries of space of Retzius:

Anterior: Posterior surface of pubic symphysis and superior rami
Posterior: Anterior wall of bladder and peritoneum
Superior: Peritoneal reflection
Inferior: Pelvic floor (levator ani, obturator internus)
Lateral: Pelvic sidewall and external iliac vessels

Anatomical Structures and Relationships

Quadrilateral surface anatomy:

Location: Medial wall of acetabulum, inner table of pelvis
Shape: Quadrilateral (four sides) - superior border is pelvic brim, inferior is obturator foramen, anterior is superior ramus, posterior is ischium
Function: Resists medial subluxation of femoral head
Fracture significance: Fractures allow medial displacement of head into pelvis

Bladder Safety in Space of Retzius

The bladder must be mobilized in the correct plane to prevent injury. Always place a Foley catheter to decompress the bladder before dissection. The correct plane is between bladder wall and pelvic bone - this is relatively avascular. If you see muscle fibers (detrusor), you're in the bladder wall. If you see peritoneum, you're too superficial. Use gentle blunt dissection with a sponge stick.

Window anatomy:

Window	Boundaries	Exposes	Fixation
First Window (Medial)	Bladder (medial) and external iliac vessels (lateral)	Quadrilateral surface, superior ramus	Quadrilateral buttress plate
Second Window (Lateral)	External iliac vessels (medial) and psoas (lateral)	Low anterior column, pelvic brim	Infrapectineal plate if needed

Internervous Plane

No true internervous plane exists for this approach.

The modified Stoppa approach works through the Space of Retzius (retropubic space), which is an extraperitoneal potential space. The dissection essentially separates the rectus abdominis muscles (inter-muscular) but then proceeds in a plane that is defined by fascial boundaries rather than nerve supplies.

Nervous Anatomy Distinction

Unlike the ilioinguinal approach which works between nerve territories (femoral/gluteal/lateral femoral cutaneous), the Stoppa approach is an intrapelvic, extraperitoneal approach. It avoids major traversing nerves of the anterior thigh. The obturator nerve is the only major nerve at risk, located on the pelvic sidewall on the obturator internus muscle.

Indications and Fracture Patterns

Isolated quadrilateral surface fractures:

Medial wall displaced
Risk of femoral head subluxation into pelvis
Best access for buttress plate application

Associated both-column fractures:

Medial displacement of articular surface
Spur sign present
Often combined with Kocher-Langenbeck for posterior component

T-type fractures:

Anterior component (stem of T) involves quadrilateral
Combined with posterior approach for transverse component

Low anterior column with quadrilateral involvement:

Inferior extent of anterior column
May combine with lateral window ilioinguinal for superior column

The Stoppa approach is specifically designed for medial structures and excels where ilioinguinal medial window is limited.

Preoperative Planning

Imaging assessment:

CT scan with 3D reconstruction: Essential for understanding fracture pattern
Assess quadrilateral displacement and rotation
Measure gap (if greater than 10mm, strongly consider fixation)
Identify associated fracture components

Fracture characteristics to document:

Quadrilateral fragment size and displacement
Posterior column involvement
Femoral head position (centrally located vs subluxed medially)
Marginal impaction
Intra-articular loose bodies

Implant planning:

Quadrilateral buttress plates (pre-contoured or standard reconstruction plates)
3.5mm cortical screws (various lengths 40-80mm)
Infrapectineal plating if anterior column involved
May need spring plates for specific patterns

Patient preparation:

Foley catheter (essential - placed before prep)
Bowel preparation if peritoneal entry anticipated
DVT prophylaxis (SCDs, chemical prophylaxis post-op)
Antibiotics (cefazolin 2g or equivalent)

Quadrilateral Plate Biomechanics

The quadrilateral buttress plate acts as an internal buttress preventing medial subluxation of the femoral head. It spans from the superior pubic ramus anteriorly to the ischium posteriorly, creating a shelf that resists medial displacement. Screw fixation into intact bone (ramus and ischium) provides stability. This is biomechanically superior to trying to reduce and fix the quadrilateral fragment itself.

Positioning

Standard Position:

Supine on a radiolucent table (essential for fluoroscopy)
Arms can be tucked or on boards (tucked preferred to allow surgeon movement)
Bump under the ipsilateral hip is usually NOT recommended as it makes the quadrilateral surface more vertical and harder to visualize. A flat pelvis is preferred.
Draping: Wide preparation from nipples to knees. Foley catheter access is essential.

Setup Checklist:

Foley Catheter: MANDATORY. Must be placed before draping to decompress bladder.
Fluoroscopy: Ensure C-arm can swing for Inlet, Outlet, and Judet views without table obstruction.
Surgeon Position: Surgeon stands on the CONTRA-lateral side to look across the pelvis at the fracture.
Assistant Position: Assistant stands on the IPSI-lateral side to retract the bladder.

Classification

Intrapelvic Approach Classification

Stoppa Approach Variants

Surgical Window Classification

Window	Boundaries	Access	Fixation Options
First Window	Bladder (medial), external iliac vessels (lateral)	Quadrilateral surface, superior ramus	Quadrilateral buttress plate
Second Window	External iliac vessels (medial), psoas (lateral)	Pelvic brim, low anterior column	Infrapectineal plating

Clinical Assessment

Preoperative Patient Assessment

General Assessment:

Hemodynamic status: Ensure stable before definitive fixation
Associated injuries: Polytrauma common with acetabular fractures
Urological status: Rule out bladder or urethral injury (blood at meatus, high-riding prostate)
Neurological exam: Document sciatic nerve function pre-operatively

Acetabular-Specific Assessment:

Soft tissue envelope: Morel-Lavallée lesion over greater trochanter (posterior injury)
Hip stability: Assess for femoral head dislocation (requires urgent reduction)
Timing: Most acetabular fractures repaired at 3-7 days (allows resuscitation, decreases bleeding)

Physical Examination for Approach Selection

Finding	Significance	Approach Implication
Anterior abdominal scars	Previous surgery	May preclude Stoppa if extensive adhesions
Midline laparotomy scar	Prior peritoneal entry	Increased difficulty in Stoppa
Pfannenstiel scar	Previous C-section/hernia	Usually still allows Stoppa
Groin mass/hernia	May need concurrent repair	Stoppa allows hernia inspection

Investigations

Imaging Protocol for Approach Planning

Standard Radiographs:

AP Pelvis: Assess overall alignment, femoral head position
Judet Views (obturator and iliac obliques): Define column involvement
Inlet/Outlet views: Assess pelvic ring if associated injury

CT Scan (Essential):

Axial images: Quadrilateral surface displacement, articular step-off
Coronal reformats: Column involvement height assessment
Sagittal reformats: Dome involvement, impaction
3D reconstructions: Fracture pattern visualization, surgical planning

Key Imaging Findings Favoring Stoppa

CT Finding	Measurement	Stoppa Indication
Quadrilateral displacement	Greater than 10mm medial	Strong indication
Femoral head subluxation	Medial migration visible	Requires buttress plate
Low anterior column	Fracture below iliopectineal eminence	Accessible via Stoppa
High anterior column	Fracture extends to iliac crest	Stoppa insufficient - need ilioinguinal

Management

Approach Selection Algorithm

Fracture Pattern to Approach Matching

Timing of Surgery

Emergent (less than 24h): Only if femoral head irreducible dislocation
Early (3-5 days): Preferred timing - allows resuscitation, reduces bleeding
Delayed (5-14 days): Still acceptable outcomes
Late (greater than 21 days): Increased difficulty, may need extensile approaches

Surgical Technique

Skin Incision Options

Pfannenstiel incision (preferred):

Transverse suprapubic incision 2-3cm above pubic symphysis
Length 10-15cm
Better cosmetic result
Familiar to general surgeons and gynecologists

Low midline incision (alternative):

Vertical midline from umbilicus toward symphysis
Better extensibility if needed
Higher wound complication rate

Pfannenstiel vs Midline

Most surgeons prefer the Pfannenstiel incision for modified Stoppa - it provides adequate exposure with better cosmetic results and lower wound complication rates. The low midline incision is reserved for cases requiring extensile exposure or when Pfannenstiel is contraindicated (previous incision, extensive scarring).

The incision choice depends on fracture pattern, patient factors, and surgeon preference.

Complications

Complications of Modified Stoppa Approach

Bladder injury management:

Recognize intraoperatively (if possible) - methylene blue test
Primary two-layer repair (3-0 absorbable suture)
Foley catheter for 7-10 days
Cystogram before catheter removal
Urology consultation if complex

Vascular injury management:

Direct pressure for control
Vascular surgery consultation
Primary repair for small injuries
Graft if extensive injury

Nerve Injury Risk Comparison

The modified Stoppa approach has significantly lower nerve injury risk compared to ilioinguinal approach. No lateral femoral cutaneous nerve at risk (this is sacrificed in 10-15% of ilioinguinal cases). Femoral nerve is not dissected. Only obturator nerve at potential risk, and this is rarely injured with proper technique. This is a significant advantage of Stoppa for isolated quadrilateral fractures.

Postoperative Care and Rehabilitation

Recovery Protocol

ImmediateDay 0-1

Foley catheter remains for 24-48 hours Monitor drain output (remove when less than 30mL/24h) DVT prophylaxis (LMWH or rivaroxaban) Early mobilization to chair with assistance

EarlyWeek 1-6

Toe-touch weight bearing (10-20kg) Hip and knee ROM exercises Avoid hip flexion greater than 90 degrees initially Continue DVT prophylaxis for 4-6 weeks

ProgressiveWeek 6-12

Partial weight bearing (50%) Increase ROM and strengthening X-rays at 6 weeks to assess healing Progress weight bearing based on healing

AdvancedMonth 3-6

Full weight bearing when callus visible Progressive strengthening Return to activities as tolerated Monitor for post-traumatic arthritis

Bladder-specific care:

Foley catheter for 24-48 hours (longer if bladder injury)
Monitor for hematuria (common, usually resolves)
Encourage fluids once catheter removed
If bladder repaired: catheter 7-10 days, cystogram before removal

Long-term outcomes:

Good-to-excellent results in 75-85% with anatomic reduction
Similar outcomes to ilioinguinal for quadrilateral fractures
Lower nerve injury complications
Better cosmetic satisfaction

Outcomes

Clinical Outcomes Summary

Functional Results:

Good to excellent: 75-85% with anatomic reduction (less than 2mm step-off)
Fair: 10-15% with imperfect reduction or complications
Poor: 5-10% with significant malreduction or post-traumatic arthritis

Comparison to Ilioinguinal Approach

Stoppa vs Ilioinguinal Outcomes

Evidence Base

Cole and Bolhofner - Modified Stoppa for Acetabular Fractures

Cole JD, Bolhofner BR • Clin Orthop Relat Res (1994)

Clinical Implication: The modified Stoppa provides superior access to the quadrilateral surface and medial pelvic wall, making it the preferred approach for these injuries.

Limitation: Single-center series; steep learning curve for surgeons unfamiliar with intrapelvic approach.

Sagi et al - Stoppa vs Ilioinguinal for Anterior Acetabulum

Sagi HC, et al • J Orthop Trauma (2014)

Clinical Implication: For isolated quadrilateral surface fractures, the modified Stoppa approach offers advantages in nerve preservation and efficiency compared to ilioinguinal medial window.

Limitation: Retrospective comparison; selection bias toward simpler fractures for Stoppa.

Keel et al - Anterior Intrapelvic Approach (Combines Stoppa Concepts)

Keel MJ, et al • J Orthop Trauma (2012)

Clinical Implication: The anterior intrapelvic approach represents evolution of the Stoppa technique, extending access laterally through a single incision.

Limitation: Technically demanding; requires expertise in both Stoppa and ilioinguinal anatomy.

Exam Viva Scenarios

Practice these scenarios to excel in your viva examination

VIVA SCENARIOStandard

Scenario 1: Quadrilateral Surface Fracture Approach Selection

EXAMINER

"A 50-year-old female has an associated both-column acetabular fracture with 15mm medial displacement of the quadrilateral surface on CT. The femoral head is subluxing medially into the pelvis. What approach would you use for the anterior component and why?"

EXCEPTIONAL ANSWER

This patient has a both-column fracture with significant medial displacement of the quadrilateral surface and femoral head subluxation - this requires anterior fixation to prevent progressive medial displacement. For the anterior component, I would use the **modified Stoppa approach** because it provides superior access to the quadrilateral surface compared to the medial window of the ilioinguinal approach. The Stoppa approach works intrapelvically through the space of Retzius - the retropubic space between the bladder and pubic symphysis. This allows me to directly visualize the quadrilateral surface and apply a buttress plate from the superior pubic ramus to the ischium, creating an internal shelf to prevent medial subluxation. The key surgical steps would be: make a Pfannenstiel incision, develop the space of Retzius bluntly, mobilize the bladder posterolaterally, identify and ligate the corona mortis, expose the quadrilateral surface, reduce the fracture, and apply a pre-contoured quadrilateral buttress plate with screws into the superior ramus anteriorly and ischium posteriorly. For the posterior component of this both-column fracture, I would also perform a Kocher-Langenbeck approach to fix the posterior column, either staged or as a two-team simultaneous procedure. The advantages of Stoppa over ilioinguinal for this fracture include: better quadrilateral access, lower nerve injury risk (no lateral femoral cutaneous nerve at risk), and better cosmetic result.

VIVA SCENARIOChallenging

Scenario 2: Intraoperative Bladder Injury Recognition

EXAMINER

"During development of the space of Retzius in a modified Stoppa approach, you notice pink fluid in the wound and the anesthesiologist reports the Foley catheter is no longer draining. What is your immediate assessment and management?"

EXCEPTIONAL ANSWER

This clinical picture strongly suggests **bladder injury** - pink fluid indicates urine (possibly with blood), and loss of Foley drainage suggests the catheter balloon may be in the wound rather than in the bladder. My immediate management would be: First, stop the dissection and assess the situation. Second, confirm bladder injury with a methylene blue test - have anesthesia instill 200-300mL of sterile saline mixed with methylene blue through the Foley catheter. If blue fluid appears in the wound, this confirms bladder injury. Third, identify the location and extent of injury - gently explore to find the defect in the bladder wall. Fourth, repair the injury primarily if identified: two-layer closure with 3-0 absorbable suture (inner layer mucosa-to-mucosa, outer layer seromuscular), ensuring watertight closure. Fifth, place a new Foley catheter under direct vision, ensuring balloon is in bladder lumen. Sixth, test the repair by filling bladder with methylene blue solution and checking for leaks. Seventh, consider urology consultation if the injury is complex (near trigone or ureteric orifices). Eighth, plan extended Foley catheter drainage (7-10 days instead of 24-48 hours) with cystogram before removal. The prevention strategy is to always work in the correct plane - between bladder wall and bone. If I see detrusor muscle fibers, I'm in the bladder wall and need to redirect. A decompressed bladder with Foley catheter makes injury less likely. After repair, I would complete the Stoppa approach as planned - bladder repair does not prevent proceeding with fracture fixation.

VIVA SCENARIOCritical

Scenario 3: Stoppa vs Ilioinguinal Decision Making

EXAMINER

"A 40-year-old male has a T-type acetabular fracture. The transverse component is minimally displaced posteriorly, but the anterior component (stem of the T) shows a low anterior column fracture with quadrilateral surface involvement and 10mm displacement. The iliac wing and high anterior column are intact. Which approach(es) would you use and why?"

EXCEPTIONAL ANSWER

This is a **T-type fracture** - a transverse component plus vertical anterior component (the 'stem' of the T). The key decision is whether both components need surgical fixation and which approach(es) to use. In this case, the transverse component is minimally displaced and may be stable enough to accept, while the anterior stem component is significantly displaced and requires fixation. For the anterior component, I have two options: (1) **Modified Stoppa alone** or (2) **Combination of Stoppa (for quadrilateral) plus lateral window ilioinguinal (for anterior column)**. My choice would depend on the exact extent of the anterior column fracture. If the fracture is primarily **low anterior column involving quadrilateral surface**, I would use **Stoppa alone** - it provides excellent access to the quadrilateral surface and low anterior column, and I can fix the fracture with a buttress plate from superior ramus to ischium. If the fracture extends high into the anterior column toward the iliac wing, I would need to **add the lateral window of ilioinguinal approach** through a separate lateral incision or combined incision to access the superior extent. For the minimally displaced transverse component, I would assess stability intraoperatively - if the anterior fixation renders the fracture stable, I may not need posterior approach. However, if there's posterior instability or posterior wall involvement, I would add a Kocher-Langenbeck approach. The advantage of Stoppa for this fracture pattern is that it directly addresses the main pathology (quadrilateral displacement) without the extensive dissection of full ilioinguinal approach, giving me excellent medial wall access with lower morbidity. I would counsel the patient that this may be a single approach (Stoppa alone) or potentially require a second approach (K-L) if intraoperative assessment shows posterior instability.

MCQ Practice Points

Space of Retzius Definition

Q: What is the space of Retzius and what are its boundaries? A: The space of Retzius is the retropubic extraperitoneal space between the bladder anteriorly and the posterior surface of the pubic symphysis. Boundaries: anterior = pubis, posterior = bladder and peritoneum, lateral = pelvic sidewall and external iliac vessels, inferior = pelvic floor.

Stoppa vs Ilioinguinal Access

Q: What is the primary advantage of modified Stoppa over ilioinguinal medial window for quadrilateral surface fractures? A: Superior direct visualization and access to the quadrilateral surface working intrapelvically. The Stoppa approach allows buttress plate application under direct vision, whereas ilioinguinal medial window has limited inferior and posterior access to the quadrilateral surface.

Quadrilateral Buttress Plate Function

Q: What is the biomechanical function of a quadrilateral buttress plate? A: The plate acts as an internal shelf preventing medial subluxation of the femoral head into the pelvis. It spans from superior pubic ramus anteriorly to ischium posteriorly, creating a mechanical buttress that resists medial displacement forces.

Nerve Injury Comparison

Q: Why does the modified Stoppa approach have lower nerve injury risk than ilioinguinal approach? A: The Stoppa approach does not dissect the lateral femoral cutaneous nerve (injured or sacrificed in 10-15% of ilioinguinal cases) and does not mobilize the femoral nerve. The only nerve at potential risk is the obturator nerve, which is rarely injured with proper technique.

When Stoppa Cannot Be Used

Q: What are the anatomical limitations of the modified Stoppa approach? A: Stoppa cannot access the iliac wing, sacroiliac joint, or high anterior column - it is limited to medial structures (quadrilateral surface, superior pubic ramus, low anterior column). These superior structures require ilioinguinal lateral window or separate lateral approach if fixation needed.

Australian Context

Australian Trauma Network

Major Trauma Services:

Acetabular fractures are tertiary referrals
Major trauma centres in each state (Level 1)
Inter-hospital retrieval for complex pelvic/acetabular injuries
Fellowship-trained pelvic surgeons at major centres

Training Pathway:

AOA Orthopaedic Training Program
Pelvic and acetabular fellowship post-FRACS
AO Pelvic Course attendance

Medicare and Coding

47936: ORIF acetabular fracture, first column
47939: ORIF acetabular fracture, second column (additional)
47942: ORIF acetabular fracture, complex (both columns)

DVT Prophylaxis Guidelines:

NHMRC recommendations for major pelvic surgery
Extended prophylaxis 28-35 days post-operatively
Chemical prophylaxis commenced 12-24h post-op

Exam Relevance

For the Australian orthopaedic exam, you must understand indications for Stoppa vs ilioinguinal, know the key anatomical structures (space of Retzius, corona mortis), and be able to describe the surgical technique step-by-step. Acetabular fracture management is a common viva topic testing decision-making and surgical planning skills.