Prospective study of the Iliac Bicrest Pubic Angle through the 3D reconstruction of the bone pelvis and the correlation with giant incisional hernia

ABSTRACT Objective: to describe and measure the Bicrista Iliaca Pubo Angle (APBCI) as a new anthropometric parameter. Correlate the measurement with patients with giant incisional hernia (HIG), in the midline of the anterior abdominal wall (AAW). Methods: measurement of APBCI, through 3D reconstruction from computed tomography (CT). Measurements performed by two observers, R and C, in 246 women and 60 men, normal adults, in order to obtain the APBCI measurement and its correlation in patients with HIG of the AAW. Results: after sample calculations, the measurement of APBCI in men: 92.5+6.3º to 93.8+6.7º; in women: 90+6.7° to 94.3+6.8° [p-value 0.337(R)/0.628(C)]. The mean age was 57.9+15.9 years (22 to 91 years). Female gender 57+15.7 years (22 to 91 years) and male 61.7+16.5 years (23 to 89 years) p=0.067. As for the distribution of the ranges from 5 to 5 degrees, there is no difference in the distribution of the angle [p-value 0.455(R)/0.672(C)]. The correlation between age and angle showed that the higher the age, the higher the APBCI. There was no variability between angle measurements: 0.97 (95% CI 0.97; 0.98). In men with HIG, the average is between 108.3+5.37º (102.92º to 113.67º), and in women, 107.8+6.64 (101.16º to 114.44º). Conclusion: the study allowed us to conclude that HIG is not just an isolated AAW defect. Determines skeletal changes, as the APBCI is influenced by the distance of the iliac crests.


INTRODUCTION
P rimary or recurrent incisional hernias (IH) of the anterolateral abdominal wall (AAW), especially those of the midline and giant (GIH), whose transverse diameter of the hernia ring is ≥10cm, have been a challenge to surgeon, both in their correction and in the interpretation of their pathophysiological consequences [1][2][3] .
More than 2,000,000 laparotomies are performed in the United States of America, of which 150,000 require reoperations due to incisional hernias 4,5 .
According to Poulose et al., in 2012, the surgical correction of ventral hernia increases in incidence and costs. A 1% reduction in relapsed cases would save 32 million dollars a year 10 .
Surgical corrections of giant hernias behave as a major risk factor for poor evolution. A prospective study involving 3,258 incisional hernioplasties revealed a rate of 13.3% of hospital readmissions, 2.2% of reoperations, and 0.5% mortality 11 .
There are several risk factors for hernia recurrence. However, we did not observe studies that indicate whether the bone morphology of the pelvis would be involved in the pathophysiological complications of GIH and its influence in the AAW reconstruction 12,13 .
Regarding the classification of IH, there were numerous proposals, few being widely used, and in these, the bone component of insertion of the abdominal wall musculature was not considered [14][15][16][17] .
In 2009, the European Hernia Society proposed a classification for incisional hernias, assigning parameters to the topography of the anterolateral abdominal wall (AAW) in terms of area and defect size 18 .
AAW hernioplasties can be performed through primary sutures, with or without the interposition of Mendes Prospective study of the Iliac Bicrest Pubic Angle through the 3D reconstruction of the bone pelvis and the correlation with giant incisional hernia prostheses, through the separation of the myoaponeurotic planes, aiming at their sliding towards the midline 19 .
As for AAW stratigraphy, it is necessary to consider that both the external oblique muscle (EOM), the internal oblique muscle (IOM), and transverse abdominis muscle (TAM) have an intimate relationship with the bone pelvis, that is, the iliac crests. The EOM is inserted in the anterior half of the iliac crest, the IOM's origin is in the two anterior thirds of the iliac crest, and the TAM's origin is the iliac crest 20,21 .
Aware of the eminently anatomical question, Radojevic, in 1958Radojevic, in to 1962, critically analyzed the pathophysiology of inguinal hernias, describing its predisposition by measuring the pelvic angle ( Figure   1A) 22

OBJECTIVES General
To describe and measure the Iliac Bicrest Pubic Angle by digital pelvimetry as a new anthropometric parameter in normal adults.

Specific
To assess the correlation of the IBCPA of normal individuals with bearers of GIH of the Midline or Medial Zones of the anterior abdominal wall.

Angle description
The IBCPA is formed by the most lateral points    We also computed the sample to obtain measurements of the same angle in GIH bearers, resulting in 18 individuals (10 females and 8 males).

Inclusion Criteria
• Men and women, adults over 21 years old.
• Images acquired with the patient in the horizontal supine position.

Exclusion Criteria
• Abnormalities or anatomical variations that prevented measurements.
• Presence of bone prostheses or orthoses.
• Prior pelvic or hip surgery.
• Imaging artifacts that impaired bone measurements.

Sample Calculation
The sample size for the IBCPA measurement was calculated with a significance level of 1% and an error of ±1º for each sex. From a pilot sample of ten women and ten men, the computed sample size was

RESULTS
We describe results through absolute and relative frequencies in the case of qualitative variables (sex), and median for the quantitative variables (age and angle value) and in the case of non-normal distribution, as verified by the Shapiro-Wilks test. We describe variables whose normality assumption was accepted through mean and standard deviation.
We compared categorical variables using the

Descriptive and statistical analysis
The study was carried out with 305 individuals, 245 females and 60 males, and measurements were taken three times by each observer. We grouped the individuals in 20 year range.
We used the Spearman's correlation test to verify if the correlation between age and pelvic angle was different from zero. All the correlations of the average age, both overall and by sex, were different from zero, positive, and weak to moderate, demonstrating that the higher the age, the higher the IBCPA (Table 5).
We used a linear regression model to assess the amount of pelvic opening, in degrees, dependent on age.

Mendes
Prospective study of the Iliac Bicrest Pubic Angle through the 3D reconstruction of the bone pelvis and the correlation with giant incisional hernia   (Table 7).

CONCLUSION
The study allowed us to conclude that: GIH is not just an isolated AAW defect. It determines skeletal changes, as the IBCPA is influenced by the retraction of the iliac crests.
The presence of a giant incisional hernia is accompanied by a greater degree of opening of the pelvis, so that the midline reconstruction of the AAW is even more subjected to the tension forces of the increase in the IBCPA.
This offers the surgeon another parameter in the application and choice of reconstruction techniques of the midline of the anterolateral abdominal wall.