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Dorsal lumbar hernias are rare pathologies of the abdominal wall. Such hernias may manifest within the superior lumbar triangle of Grynfeltt (TG) or the triangle of Petit. The aim of our study was to identify and describe variations in the size and anatomy of the TG. The triangle was studied in 50 adult human cadavers, and dimensions and surface area were measured. The TG was identified in 82% of cases. Based on surface area parameters, we were able to classify the triangles into four distinct types. Type I (50%), or small triangles, had a surface area of <5 cm2. Type II (22%, n = 22) were defined as triangles intermediate in size with surface areas of 5-15 cm2. Type III (10%, 10) were large triangles with surface areas of >15 cm2. Finally, Type 0 (18%, 18) did not exhibit a triangle; instead, the aponeurosis of the transversus abdominis was enclosed by the external abdominal oblique muscle and the sacrospinalis muscle. We present these data with the hope that after further investigation in a clinical setting, they may serve practitioners in predicting which morphometric variations of the TG most predispose patients to posterior wall herniation. [PUBLICATION ABSTRACT]
Hernia (2008) 12:227231DOI 10.1007/s10029-008-0354-4
APPLIED ANATOMY
The clinical anatomy of the triangle of Grynfeltt
M. Loukas D. El-Zammar M. M. Shoja R. S. Tubbs L. Zhan B. Protyniak Y. Krutoshinskaya
Received: 10 August 2007 / Accepted: 1 February 2008 / Published online: 19 February 2008 Springer-Verlag 2008
Abstract Dorsal lumbar hernias are rare pathologies of the abdominal wall. Such hernias may manifest within the superior lumbar triangle of Grynfeltt (TG) or the triangle of Petit. The aim of our study was to identify and describe variations in the size and anatomy of the TG. The triangle was studied in 50 adult human cadavers, and dimensions and surface area were measured. The TG was identiWed in 82% of cases. Based on surface area parameters, we were able to classify the triangles into four distinct types. Type I (50%), or small triangles, had a surface area of <5 cm2.
Type II (22%, n = 22) were deWned as triangles intermediate in size with surface areas of 515 cm2. Type III (10%,10) were large triangles with surface areas of >15 cm2.
Finally, Type 0 (18%, 18) did not exhibit a triangle; instead, the aponeurosis of the transversus abdominis was enclosed by the external abdominal oblique muscle and the sacrospinalis muscle. We present these data with the hope that after further investigation in a clinical setting, they may serve practitioners in predicting which morphometric variations of the TG most predispose patients to posterior wall herniation.
Keywords Triangle of Petit Superior lumbar triangle Anatomy Hernia
Introduction
In 1886, Grynfeltt was the Wrst to report a hernia through the superior lumbar triangle, which now bears his name [1]. In 1870, Lesshaft had identiWed a separate case of herniation through the superior lumbar triangle [2]. Consequently, this triangle is sometimes, although less commonly, referred to as the triangle of Lesshaft. As described in the literature, the superior lumbar triangle, or Grynfeltts triangle (TG), is an inverted triangle (with its apex directed inferiorly) related to the 12th thoracic and Wrst lumbar nerves. It is bound by the posterior border of the internal oblique muscle anteriorly, the anterior border of the sacrospinalis muscle posteriorly, and has the 12th rib and the serratus posterior inferior muscle as its base, the external oblique and the latissimus dorsi muscles as its roof, and the aponeurosis of the transversus abdominis as its Xoor [3, 4].
Goodman and Speese found the TG to exist in 93% of 76 cadavers [3]. The morphology of the TG depends on several factors including the development of the muscles forming the borders of the triangle, the position and length of the 12th rib as well as the sites of its muscle attachments, and Wnally the site of attachment of the latissimus dorsi [5]. A weakened area of the TG has been identiWed as the position directly below the 12th rib where the transversalis fascia is not shielded by the external oblique and where it is penetrated by the subcostal neurovascular bundle [6]. Herniation at the TG may be congenital, acquired, or iatrogenic (incisional) [7] and presents symptomatically as nausea, vomiting, renal deWciency, aching pain, and swelling in the lumbar region [7, 8]. Several clinical cases of acquired TG
M. Loukas (&) D. El-Zammar L. Zhan B. Protyniak Y. KrutoshinskayaDepartment of Anatomical Sciences, School of Medicine, St Georges University, Grenada, West Indiese-mail: [email protected]
M. M. ShojaTuberculosis and Lung Disease Institute, Tabriz Medical University, Tabriz, Iran
R. S. TubbsSection of Pediatric Neurosurgery, Childrens Hospital, Birmingham, AL, USA
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hernias have been reported [79]. Incisional posttraumatic hernias have also been documented after nephrectomy and aortic aneurysm repair [10].
The aim of the present study is to describe variations in the anatomical location and morphology of the superior lumbar triangle and report any herniation of abdominal contents through the TG in the cadavers examined. We also hope that our Wndings will assist surgeons in lumbar hernial repairs and reduce the incidence of postoperative incisional hernias following nephrectomy, aortic aneurysm repair, iliac bone graft harvest, and latissimus dorsi myocutaneous Xap.
Materials and methods
Twenty-Wve adult human formalin-Wxed cadavers (12 females and 13 males were examined at the University of Alabama at Birmingham. An additional 25 adult human formalin-Wxed cadavers (15 females and 10 males) were examined at St. Georges University in Grenada. None of the cadavers revealed any evidence of gross pathology, previous surgical procedures, or traumatic lesions over the back. The mean age for this group was 68 years (range of 5984 years).
Following the removal of the skin and superWcial fascia of the lower back, the iliac crest inferiorly, the medial edge of the external abdominal oblique, and the lateral edge of the latissimus dorsi were identiWed and dissected. The latissimus dorsi was reXected superiorly to expose the 12th rib, anterior border of sacrospinalis muscle, and serratus posterior inferior muscle. SpeciWc attention was given to the borders and the Xoor of the TG and measurements of its length, width, and surface area were made as follows: Following preliminary examination, images of all dissected specimens were recorded with a Sony digital camera (Nikon Coolpix S5) and studied using a computer-assisted image analysis system, Lucia software 5.0 (2000, edition for Windows XP) made by Nikon (Laboratory Imaging). The digital camera was connected to an image processor (Nvidia GeForce 6800 GT) linked to a mainframe computer. Digitized images of the nerves, together with the surrounding structures, were stored in the Lucia program (2,048 1,536 pixels). After applying a standard 1-mm scale to all images, the program was able to calculate pixel diVerences between two selected points, such as the origin and termination of a muscle border, as previously described [11]. This allowed easy and accurate translation of pixel diVerences into metric measurements. SpeciWcally, we measured the length of the internal abodominal oblique muscle, anterior border of sacrospinalis muscle, and the junction of 12th rib and serratus posterior inferior muscle. Accordingly, we have calculated the surface area occupied
by each triangle. Statistical analysis was performed using t-test with signiWcance set at P < 0.05.
Results
Morphological patterns in the dimensions of the TG identi-Wed in this study demonstrated wide variation. To facilitate comparisons between specimens and to analyze the various patterns, the results of the surface area measurements were classiWed into four types, which were designated by Roman numerals I, II, III, and 0. Overall, the TG was identiWed in 82 (82%) sides. Type I TG were small triangles and were identiWed in 50% (50 triangles) of sides and exhibited a surface area of <5 cm2 (Fig. 1). Type II (22%, 22) was applied to triangles of an intermediate size with surface areas of 515 cm2 (Fig. 2). Type III (10%, 10), was applied to large triangles exposing a large component of the aponeurosis of the transversus abdominis with surface areas of >15 cm2 (Fig. 3). Finally, type 0 (18%, 18) was applied in the remaining sides in which no triangle was formed (Fig. 4). In these cases, the aponeuorosis of the transversus abdo-minis was covered by the internal abdominal oblique muscle and the sacrospinalis muscle.
Fig. 1 Type I triangle of Grynfeltt
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Fig. 4 Type 0 triangle of Grynfeltt. In these cases, the aponeuorosis of the transversus abdominis was covered by the internal abdominal oblique and sacrospinalis muscles
Fig. 2 Type II triangle of Grynfeltt
Fig. 3 Type III triangle of Grynfeltt
The results of our morphometric analysis of the TG were as follows: For the right TG, the mean length of the sacrospinalis muscle was 4.54 cm with a range of 3.38.6 cm; of
the external abdominal oblique 4.52 cm with a range of2.27.2 cm; of the serratus posterior inferior and 12th rib2.33 cm with a range of 1.53.7 cm. The mean length of the sacrospinalis muscles was 4.33 cm with a range of 2.88.2 cm; of the external abdominal oblique 4.1 cm with a range of 1.56.9 cm; of the serratus posterior inferior and 12th rib 2.1 cm with a range of 1.43.1 cm.
With regards to symmetry of the TG patterns, it was noted that types I, II, and III appeared to be symmetrical in 30% (30), 11% (11) and 1% (1) of sides, respectively. We also observed that the right side tended to possess larger triangles than the left. There was no signiWcant diVerence in race, gender, age, or the institutions where the cadavers derived from in regard to dimensions of the triangle (Students t-test; P >0.05).
Discussion
Lumbar hernias are rare occurrences. The Wrst clinical case was described by DeGarangeot in 1731 [5, 12, 13]. Since then, an increasing number of reports have expanded our understanding of lumbar herniations. Review of the literature found that hernias are classiWed on the basis of anatomical position, such as superior, inferior, or diVuse; and on the basis of cause as either congenital, acquired, or incisional [7]. According to Orcutt, all congenital hernias in the lumbar region are reported to have perforated through the inferior lumbar triangle [5]. Conversely, acquired hernias that are of a traumatic nature constitute 80% of reported lumbar hernias [9] and are predominantly associated with the superior lumbar triangle due to the frequency of surgical interventions in this area and because it is the
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thinnest site in the posterolateral abdominal wall [5]. It is also worth noting that superior lumbar hernias are associated with the TG, whereas inferior lumbar hernias are related to the triangle of Petit [14]. In our previous study concerning a morphometric analysis of the triangle of Petit, we classiWed this variable anatomical triangle into four types based on the size of surface area (type I smallest, type II intermediate, type III largest, Type 0 no triangle observed). We hypothesize that type III TP may be more prone to herniation due to its larger surface areas. However, most authors agree [1519] that the TG is larger than the triangle of Petit and consequently is the more common site for lumbar hernias.
The aforementioned acquired hernias are subdivided into two categories: primary (55%) and secondary (25%) following trauma or surgery [9, 20]. Traumatic hernias may manifest postoperatively due to Xank incisions, renal or suprarenal surgery, and iliac bone graft harvesting [2124], or accidently, due to abscesses, direct force, or penetrating wounds [24]. Salameh and Salloum documented two cases of Xank incisional hernias, the Wrst following abdominal aortic aneurysm and the second following radical nephrectomy [10].
Diagnosis of herniation through the superior lumbar triangle can be made by palpation or radiographic study, with more sophisticated imaging technology, such as computerized topography (CT) and magnetic resonance imaging (MRI), proving most eVective [5, 9, 25]. In one report, contrastenhanced CT showed herniation of part of the descending colon and the surrounding retroperito-neal fat through the TG in an 85-year-old patient [9]. Since CT is able to demarcate the anatomy and content of hernias, it serves as a useful tool in the diVerential diagnosis of hernias from renal carcinomas, abscess, and hematomas [9].
Surgical repair is the dominant treatment for lumbar hernias. Akin to the surgical management of abdominal hernias, the sac should be excised and the defect closed [26]. Closure of the defect typically involves local tissue Xaps or the use of prosthetic mesh material [26, 27]. When strangulation is observed, bowel resection may be required [9]. In addition, noninvasive laparoscopic techniques have been employed in lumbar hernia repair, reducing morbidity, pain, and hospitalization, with minimal scarring [28].
Previous studies have quantiWed the diameters of the lumbar hernias [29], but the surface area of TG has not yet been documented. Zhou et al. [29] described the average diameter of lumbar hernias as ranging from 3 to 7 cm with an average of 4.7 cm. We believe, however, that quantifying the surface area of the TG may serve as an indicator for inferior lumbar herniations.
Conclusions
This is the Wrst study documenting measurements for the TG, which represents the site of potential superior lumbar herniation and is a site of anatomic weakening in the lateral abdominal wall. We have classiWed this variable anatomical triangle into four types based on the size of surface area (type I smallest, type II intermediate, type III largest, type 0 no triangle observed). We hypothesize that type III TG may be more prone to herniation due to its larger surface areas. Further studies aimed at clinically investigating the relationship between the types of TGs and superior lumbar herniations are now necessary to add a clinical perspective to our morphological Wndings.
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