What is the significance of the critical view of the myopectineal orifice in hernia repair surgery?

Critical View of the Myopectineal Orifice in Hernia Repair

Definition and Anatomical Significance

The critical view of the myopectineal orifice (MPO) is a safety concept that ensures complete visualization and adequate coverage of all potential hernia sites in the groin during minimally invasive inguinal hernia repair, analogous to the critical view of safety in laparoscopic cholecystectomy. 1

The MPO represents the entire weak area of the abdominal wall where all inguinal hernias occur, bounded by specific anatomical landmarks that must be identified during repair. 2, 1

Anatomical Boundaries and Dimensions

The MPO has well-defined dimensions that guide appropriate mesh sizing:

• In males, the MPO measures approximately 7.6 cm × 7.6 cm (equal width and height), while in females it measures 8.1 cm × 5.3 cm (wider than tall). 3

• The average MPO dimensions across both genders are 7.8 cm in width and 6.5 cm in height, with the weak inguinal area cranial to the inguinal ligament measuring 4.5 cm in height. 3

• Body size correlates with MPO height (r = 0.5005), and interspinous distance shows strong correlation with MPO height (r = 0.7653). 3

Clinical Application: The Ten Golden Rules

The critical view of the MPO provides a systematic approach to safe minimally invasive hernia repair (TAPP, TEP, ETEP, RTAPP) by combining anatomical understanding with technical execution. 1

Achieving the critical view requires complete visualization of the "inverted Y" anatomy and the five essential triangles of the posterior groin, ensuring all potential hernia sites are identified before mesh placement. 1

This concept addresses a fundamental principle: since all recurrences occur within the MPO area, complete coverage of this orifice is mandatory for preventing recurrence. 4

Mesh Sizing Based on MPO Measurements

Appropriate mesh dimensions must account for MPO size plus adequate overlap:

• For hernias with defects <3 cm, the recommended mesh size is 13.2 cm × 10.4 cm (adding 2-3 cm overlap to the 95th percentile MPO dimensions of 9.2 cm × 6.4 cm). 2

• For hernias with defects ≥3 cm, the recommended mesh size is 15.6 cm × 13.0 cm (adding 2-3 cm overlap to the 95th percentile MPO dimensions of 9.6 cm × 7.0 cm). 2

• A standard 10 cm × 8 cm mesh is suitable for both genders in routine cases: it covers the entire MPO including the infraligamental part in females, while preferentially covering the weak inguinal area in males. 3

• Mesh must overlap the defect edge by 1.5-2.5 cm to ensure adequate coverage and prevent recurrence. 5

Impact on Recurrence Rates

The critical view concept directly addresses the primary cause of hernia recurrence:

• Using appropriate mesh sizes based on intraoperative MPO measurement reduces recurrence rates to 0.2% in TEP repair. 2

• Covering only the MPO with a small mesh (8-10 cm × 6-7 cm) using the inguinal approach achieves recurrence rates of 0.7% with 63-month median follow-up. 4

• This targeted approach avoids the complications of oversized meshes spread over iliac vessels and bladder, which can cause future difficulties in urogenital or vascular procedures. 4

Technical Advantages Over Traditional Approaches

The critical view of the MPO offers several advantages:

• It provides a standardized endpoint for dissection and mesh placement across all minimally invasive techniques (TAPP, TEP, ETEP, RTAPP), similar to how the critical view of safety standardized laparoscopic cholecystectomy. 1

• The concept allows identification of occult contralateral hernias, which are present in 11.2-50% of cases during laparoscopic examination. 5

• It ensures that mesh reinforcement addresses the naturally weak area between the transversus abdominis arch and the iliopubic tract, which traditional mesh-only approaches may inadequately cover. 6

Common Pitfalls to Avoid

• Insufficient coverage of the MPO is an important risk factor for hernia recurrence; failure to achieve the critical view before mesh placement increases this risk. 2

• Misplacement of the mesh outside the MPO boundaries accounts for technical failures, as demonstrated by the single recurrence in a series where mesh was incorrectly positioned. 4

• Using undersized mesh that fails to provide 1.5-2.5 cm overlap beyond the MPO edges compromises the repair integrity. 5, 2

• Placing excessively large meshes beyond the MPO boundaries creates unnecessary foreign body burden and potential complications without improving recurrence rates. 4