Iliac intramedullary stabilization for Type IIIA fragility fractures of the pelvis.

There have been few reports on fixation of Rommens classification Type IIIA fragility fractures of the pelvis (FFPs). Here, we present our less invasive surgical technique, called iliac intramedullary stabilization (ILIS), for the internal fixation of Type IIIA FFPs. The technique involves a closed reduction, termed the femur internal rotation reduction method (FIRM), whereby the fracture fragments are repositioned using lateral rotators by internally rotating the femur while the patient is in the prone position. Two iliac screws are inserted on the ilium bilaterally via the supra-acetabular bone canal during FIRM and connected with two transverse rods and two cross connectors. We refer to this internal fixation procedure as ILIS. We retrospectively recruited patients with Type IIIA fractures, treated using this procedure, at our institute between October 2017 and October 2019. We evaluated operative and post-operative outcomes. We enrolled 10 patients (9 women and 1 man; mean age, 85.2 years) who were followed up for over 6 months. All patients suffered FFPs after falling from a standing position. The mean operative time was 145.1 (range, 94-217) minutes, and the mean blood loss was 258.5 (range, 100-684) ml. All patients were allowed full weight bearing from post-operative day 1. All patients achieved bone union and regained their pre-injury walking ability at 6 months after surgery without evident secondary displacement. In conclusion, our ILIS technique allows less invasive internal fixation of Type IIIA FFPs with adequate stability for full weight bearing from post-operative day 1.

Anterior acetabular retractors and the femoral neurovascular bundle in anterior total hip arthroplasty: a cadaveric study.

PURPOSE: The direct anterior approach for primary total hip arthroplasty (THA) has become increasingly popular in recent years. Nerve compression or traction with a retractor is a common cause of nerve injury in this approach. The purpose of this cadaveric study was to evaluate the anatomic relationship of the femoral neurovascular bundle to the anterior acetabular retractor during direct anterior approach THA. METHODS: Eleven fresh-frozen cadavers underwent a standard direct anterior THA, with placement of an anterior acetabular retractor in the usual fashion between the iliopsoas and acetabulum for visualization during acetabular preparation. Careful dissection of the femoral triangle was performed, and the distances from the anterior retractor tip to the femoral nerve, artery, and vein were recorded and analyzed as mean distance ± standard deviation. RESULTS: In all 11 cadavers, the retractor tip was medial to the femoral nerve. The mean distance from retractor tip to femoral artery and vein was 5.9 mm (SD = 5.5, range 0-20) and 12.6 mm (SD 0.7, range 0-35), respectively. CONCLUSIONS: Surgeons should be aware of the proximity of the neurovascular structures in relation to the anterior acetabular retractor in the direct anterior approach, taking care to avoid perforating the iliopsoas muscle during retractor insertion and limit excessive traction to prevent nerve injury.

The correlation between femoroacetabular impingement and superior retinacular artery interruption.

The aim of this study was to investigate the relationship between femoroacetabular impingement (FAI) and superior retinacular artery interruption using plain radiographs and digital subtraction angiography (DSA).Sixty-one patients included in this study were divided into 2 groups based on the superior retinacular artery integrity as evaluated on DSA images. Group A included intact arteries: 33 patients (24 men, 9 women,); group B included interrupted arteries: 28 patients (21 men, 7 women). The parameters of abnormal radiographic findings thought to be associated with FAI, including positive crossover or figure-of-eight sign of acetabulum, lateral center edge angle (LCEA) >40°, Tönnis angle <0°, positive posterior wall sign, alpha angle >50°, and coxa profunda, were evaluated in all patients through plain radiographs.The cross-over sign (Group A: 0, Group B: 8, P = .0035), LCEA (Group A: 1, Group B: 7, P = .0190), Tönnis angle (Group A: 3, Group B: 13, P = .0026), and alpha angle (Group A: 7, Group B: 17, P = .0039) differed significantly between both groups. However, there were no statistically significant differences in posterior wall sign (Group A: 9, Group B: 12, P = .3143) or coxa profunda (Group A: 12, Group B: 8, P = .7096).Patients with interrupted blood supply of the superior retinacular arteries displayed more parameters of abnormal radiographic findings associated with FAI thereby indicating potential correlation between FAI and the interruption of superior retinacular arteries.

Orthopedic implications of the corona mortis: a case report / Implicaciones ortopédicas de la corona mortis: reporte de un caso

SUMMARY: Corona mortis is classified as a connection between the inferior epigastric and obturator vessels over the superior pubic ramus. Its incidence varies among different studies. The corona mortis is an extremely important anatomical variation as it can be injured in a great number of procedures. Moreover, it can also be injured during pelvic or acetabular fractures. A male cadaver fixed in a 10 % formalin solution had its pelvic region dissected and an arterial corona mortis was observed on its right side. The left hemipelvis presented no variations whatsoever. This vessel was measured with the aid of a digital caliper. We aim to report this variation and address - from an orthopedic point of view - the clinical and surgical significance of the corona mortis.

RESUMEN: La corona mortis es clasificada como una conexión entre los vasos epigástricos inferiores y obturadores sobre la rama superior del pubis. Su incidencia varía según los diferentes estudios. La corona mortis es una variación anatómica extremadamente importante, ya que se es posible dañarla en un número significativo de procedimientos. Además, también puede resultar lesionada durante las fracturas pélvicas o acetabulares. Durante la disección de un cadáver de sexo masculino fijado en solución de formalina al 10 %, se observó la corona mortis arterial en el lado derecho de la región pélvica. El lado izquierdo de la pelvis no presentó ninguna variación. Se midió la corona mortis con ayuda de un calibre digital. Nuestro objetivo fue informar sobre esta variación y abordar - desde el punto de vista ortopédico - la importancia clínica y quirúrgica de la corona mortis.

Surgical anatomy of the pelvic vasculature, with particular reference to acetabular screw fixation in cementless total hip arthroplasty in Asian population.

PURPOSE: Pelvic vascular injury is a serious complication associated with acetabular component setting with screw fixation in cementless total hip arthroplasty (THA). In this study, we investigated the safety zone for acetabular component setting with screw fixation in cementless THA as a means to prevent pelvic vascular injury. METHODS: Thirty left hip joints of Japanese cadavers (11 males and 19 females) were analyzed. We used a hemispherical measuring cup with 52 guide holes designed to allow vertical insertion of a Kirschner wire. After the measuring cup was placed on the acetabulum, the Kirschner wire was inserted from each guide hole to examine the anatomical relationship between the acetabulum and the pelvic vessels. We calculated the frequency of pelvic vessel punctures and measured the distance from the acetabular surface to the pelvic vessels at each guide hole. RESULTS: Our findings revealed that pelvic vessels do not exist in certain parts of the posterior area of the acetabulum. Furthermore, in this area, intrapelvic vessels are either lacking or located at a distance ≥31 mm from the surface of the acetabulum. CONCLUSION: The posterior area of the acetabulum, excluding its central portion, appeared to be the safety zone for acetabular screw fixation in Japanese cadavers.

Acetabular labrum blood flow in developmental dysplasia of the hip: an intraoperative in vivo study using laser Doppler flowmetry.

BACKGROUND: The vascular supply to the acetabular labrum is important in the treatment of labral lesions. However, in vivo blood flow measurements in the acetabular labrum have not been described in the literature. The purpose of this study was to examine this blood flow in vivo using laser Doppler flowmetry (LDF) in patients with acetabular dysplasia. METHODS: Periacetabular osteotomy combined with arthroscopy was performed in 47 consecutive patients (three males, 44 females; mean age at surgery, 35.6 years; range, 15-60 years). In all patients, blood flow in the acetabular labrum was measured with LDF during arthroscopy. The acetabular labral lesions were categorized according to the modified Beck classification: detachment and full-thickness labral tears were assigned to the T group and normal labrum to the N group. Blood flow rates in the acetabular labrum were compared between the T and N groups. The associations between labral blood flow and the lateral center-edge angle (CEa) and patient age were also evaluated. RESULTS: The T and N groups comprised 31 and 16 patients, respectively. The mean blood flow rate was 1.94 ± 0.41 ml/min/100 g in the T group and 1.94 ± 0.34 ml/min/100 g in the N group, with no significant difference between the groups (P = 0.884). No association was noted between blood flow and either the CEa or patient age (ß = -0.018, P = 0.077 and ß = -0.001, P = 0.770, respectively). CONCLUSIONS: On LDF, blood flow in the acetabular labrum was present in all patients, regardless of the severity of acetabular labral tears, CEa, or age.

Hip Vascularity: A Review of the Anatomy and Clinical Implications.

Throughout development, the vascular supply to the proximal femur and acetabulum undergoes a series of changes during which it is susceptible to injury. Before age 3 months, the ligamentum teres and lateral epiphyseal arteries are the dominant supply to the developing head. The dominant supply shifts to the lateral epiphyseal vessels by age 18 months. The distinct metaphyseal and epiphyseal circulations of the adult proximal femur form in adolescence when an increasingly rich metaphyseal circulation supplies the subphyseal region, terminating at the physeal plate. The acetabular blood supply derives from two independent systems, with the dominance of each changing throughout maturity. Most descriptions of the vascular contributions to the proximal femur and acetabulum have been gross anatomic and histologic studies. Advanced imaging studies (eg, CT angiography, perfusion MRI) have added to our understanding of the vascular anatomy of the proximal femur and acetabulum, its changes throughout development, and its clinical implications.

Significance of preoperative 3D-CT angiography for localization of the femoral artery in complicated THA.

BACKGROUND: Major vascular injury is one of the most devastating complications in total hip arthroplasty (THA). Risk for intraoperative vascular injury is increased when the normal vascular anatomy is distorted by previous surgery or dislocation with displacement. Therefore, an appreciation of the vascular anatomy in relation to the anticipated surgical field is critical to avoid this complication during preoperative assessment for a complicated THA. METHODS: Preoperative three-dimensional (3D) CT angiography was performed for 24 complicated THAs when altered vascular anatomy around the acetabulum was suspected. When assessing the CT images, the presence of apparent proliferation of vessels close to the original acetabulum as well as a distance of <10 mm from the artery to the acetabulum was deemed a potential risk factor for intraoperative vascular injury. Additionally, the relationships of clinical characteristics and the presence of these risk factors were analyzed to identify the patient population at risk. RESULTS: The incidence of proliferation of collateral vessels was higher in patient groups with proximal femoral migration of 5 cm or more and multiple previous surgeries prior to the index THA. Moreover, in three ankylosed hips, lateral deviation of the main vascular trunk with an artery-acetabulum distance of <10 mm was identified in all cases. CONCLUSION: Preoperative 3D-CT angiography in cases of complicated THA revealed altered vascular anatomy which may increase the risk for intraoperative vascular injuries. Patient characteristics related to the risk for this complication were marked proximal femoral migration, multiple previous surgeries, and hip ankylosis. Preoperative image examination of the vascular anatomy is thought to help reduce the risk of inadvertent vascular injury in these complicated THA cases.

Blood perfusion and bone formation before and after minimally invasive periacetabular osteotomy analysed by Positron Emission Tomography combined with Computed Tomography.

PURPOSE: Sufficient blood perfusion is essential for successful bone healing after periacetabular osteotomy (PAO). The purpose of this study was to quantify blood perfusion and bone formation before and after PAO analysed by positron emission tomography (PET) combined with computed tomography (CT). METHODS: Twelve dysplastic patients (nine women) were included consecutively in the study and all were operated upon by the senior author (KS). Median age was 33 (23-55) years. Initially, two patients were PET scanned in a pilot study to test our models for calculation of the physiological parameters. The following ten patients had their hip joints PET/CT scanned immediately before PAO and three to four weeks after. Oxygen-15-water was used to quantify blood perfusion and Flourine-18-fluoride was used to produce quantitative images interpreted as new bone formation in the acetabular fragment. RESULTS: The blood perfusion of the operated acetabulum before surgery was 0.07 ± 0.02 ml/min/ml, and after surgery 0.19 ± 0.03 ml/min/ml (p = 0.0003). Blood perfusion of the non-operated acetabulum was 0.07 ± 0.02 ml/min/ml before PAO and 0.07 ± 0.02 ml/min/ml after surgery (p = 0.47). The fluoride-clearance per volume bone of the operated acetabulum was 0.02 ± 0.01 ml/min/ml preoperatively, and 0.06 ± 0.01 ml/min/ml postoperatively (p = 0.0005). Fluoride-clearance of the non-operated acetabulum was 0.01 ± 0.01 ml/min/ml before PAO and 0.02 ± 0.01 ml/min/ml after PAO (p = 0.49). CONCLUSION: Blood perfusion and new bone formation increased significantly in the acetabular fragment. Thus, the results of this study do not support the concern about surgically damaged vascularity after PAO.

Slipped capital femoral epiphysis: relevant pathophysiological findings with open surgery.

BACKGROUND: Traditionally arthrotomy has rarely been performed during surgery for slipped capital femoral epiphysis (SCFE). As a result, most pathophysiological information about the articular surfaces was derived clinically and radiographically. Novel insights regarding deformity-induced damage and epiphyseal perfusion became available with surgical hip dislocation. QUESTIONS/PURPOSES: We (1) determined the influence of chronicity of prodromal symptoms and severity of SCFE deformity on severity of cartilage damage. (2) In surgically confirmed disconnected epiphyses, we determined the influence of injury and time to surgery on epiphyseal perfusion; and (3) the frequency of new bone at the posterior neck potentially reducing perfusion during epimetaphyseal reduction. METHODS: We reviewed 116 patients with 119 SCFE and available records treated between 1996 and 2011. Acetabular cartilage damage was graded as +/++/+++ in 109 of the 119 hips. Epiphyseal perfusion was determined with laser-Doppler flowmetry at capsulotomy and after reduction. Information about bone at the posterior neck was retrieved from operative reports. RESULTS: Ninety-seven of 109 hips (89%) had documented cartilage damage; severity was not associated with higher slip angle or chronicity; disconnected epiphyses had less damage. Temporary or definitive cessation of perfusion in disconnected epiphyses increased with time to surgery; posterior bone resection improved the perfusion. In one necrosis, the retinaculum was ruptured; two were in the group with the longest time interval. Posterior bone formation is frequent in disconnected epiphyses, even without prodromal periods. CONCLUSIONS: Addressing the cause of cartilage damage (cam impingement) should become an integral part of SCFE surgery. Early surgery for disconnected epiphyses appears to reduce the risk of necrosis. Slip reduction without resection of posterior bone apposition may jeopardize epiphyseal perfusion. LEVEL OF EVIDENCE: Level IV, retrospective case series. See Guidelines for Authors for a complete description of levels of evidence.

Location of intrapelvic vessels around the acetabulum assessed by three-dimensional computed tomographic angiography: prevention of vascular-related complications in total hip arthroplasty.

BACKGROUND: During total hip arthroplasty (THA), the external iliac, femoral, and obturator vessels are at risk of vascular injury when penetrating the inner cortex of the pelvis. The purpose of this study was to clarify the location of these vessels using three-dimensional computed tomographic angiography (3DCT-A). METHODS: We enrolled 100 subjects (200 hips) without hip disease and performed examinations on the following. (1) External iliac-femoral vessels: we measured the shortest distance from these vessels to the pelvis on axial CT images and investigated the factors affecting distance. The anatomical course of the iliac artery was classified as straight, curved, or tortuous, and the correlation between course and age was established. (2) Obturator vessels: we measured the shortest distance from the obturator vessels to the quadrilateral surface on axial CT images. (3) Visualization of pelvic vessels was through the pelvis by dual-phase 3DCT-A. RESULTS: (1) The external iliac vein was located significantly closer to the pelvis than the artery, especially on the left side and in aged and female subjects. The single-curved and tortuous double-curved vessel types were found in aged subjects, and external iliac vessels of these types were closer to the pelvis than vessels of the straight type. In 36 subjects, the external iliac veins lay directly on the osseous surface of the pelvis (right 16, left 36). Of these 36 subjects, only one had straight-type vessels. (2) Obturator vessels were located just behind the acetabulum near the obturator foramen. (3) Reconstructed 3DCT images enabled us to visualize the pelvic vessels and demonstrated the danger area for penetrating the inner cortex of the pelvis. CONCLUSION: Understanding the anatomical orientation of the pelvic vessels around the acetabulum using 3DCT-A could be helpful for preventing vascular injury during THA.

Modified medial Stoppa approach for acetabular fractures: an anatomic study.

BACKGROUND: The modified medial Stoppa approach is an alternative and new surgical approach to access to the internal pelvis and medial wall of the acetabulum. There is little information about the clinical anatomic specifications of exposure in the literature. In this study, the pertinent surgical anatomy that involved the modified medial Stoppa approach was further defined and the anatomic positions and variations of the structures seen in the surgical site were analyzed. METHODS: We dissected five formalized cadavers to present structures at risk in a standard modified medial Stoppa approach. The internal iliac artery and branches were colored with latex injection in formalized cadavers. Morphometrical measurements of the neurovascular structures adjacent to quadrilateral surface and their anatomic variations were noted. RESULTS: It was detected that the obturator vessels and nerve and the iliolumbar vessels were primarily the structures at risk. Obturator vessels and nerve were the most important structures to pay attention because of their direct contact to quadrilateral surface. There was communication (corona mortis) between obturator and inferior epigastric veins in 4 (40%) of 10 hemipelvises. CONCLUSIONS: Before clinical applications, performing cadaver dissection is important to minimize intraoperative complications. This study was the first anatomic study in the literature that reveals the structures that are at risk during surgical treatment of acetabular fractures, which was treated with the modified medial Stoppa approach.

Is the obturator artery safe when performing ischial osteotomy during periacetabular osteotomy?

The purposes of this study were (1) to evaluate the actual distance between the obturator artery and the ischial osteotomy site when performing periacetabular osteotomy via an anterior approach and (2) to determine a safe method to avoid injuring the obturator artery during this procedure. Twenty-nine hemipelves from cadavers were used in this study. The mean distance between the obturator artery and the ischial osteotomy site was 35.6 ± 7.5 mm and always exceeded 20 mm. Therefore, the procedure can be performed safely when a chisel blade of 20 mm or shorter is used.

Vascular supply to the acetabular labrum.

BACKGROUND: The acetabular labrum plays an important role in hip joint stability and protection of the articular cartilage of the hip. Despite this, few investigators have evaluated its microscopic vasculature and, to our knowledge, none has assessed its macroscopic blood supply. The purposes of this study were to identify the origin and course of the vascular supply to the acetabular labrum to determine if this blood supply is affected by a labral tear. METHODS: Colored silicone was injected into the vascular tree proximal to thirty-five hips in twenty-eight fresh cadavers. Twenty-four hours after injection, anatomic dissection was performed and the vessels supplying the labrum were followed from their origin to their final distribution. Additionally, labral segments of fifteen randomly selected hips were resected to assess the acetabular rim's vascular contribution, and fifteen hips were dislocated for complete intra-articular inspection of the labrum. RESULTS: Radial branches of a previously described periacetabular periosteal vascular ring were identified as the source of labral blood supply in all thirty-five hips. These branches coursed toward the hip joint on the periosteal surface, penetrated the joint capsule near its innominate insertion, and continued within a loose connective-tissue layer on the capsular surface of the labrum. No contribution from the hip capsule, synovial lining, or osseous acetabular rim could be demonstrated. An intact vascular supply was identified in all seven hips with a labral tear. CONCLUSIONS: The acetabular labrum receives its blood supply from radial branches of a periacetabular periosteal vascular ring that traverses the osseolabral junction on its capsular side and continues toward the labrum's free edge. The hip capsule, the synovial lining, and the osseous acetabular rim do not appear to provide substantial contributions to the labral blood supply.

Osteotomia periacetabular de Ganz: anatomía vascular en relacion co el acetabulo y la cabeza femoral / Ganz periacetabular osteotomy: vascular anatomy in relation with the acetabulum and femoral head

Introducción: Esta presentación estudia el fundamento vascular de la técnica quirúrgica propuesta por Ganz, evaluando la relación entre esta cirugía y la anatomía vascular del acetábulo y la cabeza femoral. Materiales y métodos: La evaluación se realizó mediante el estudio de la irrigación acetabular en descripciones clásicas sobre el tema; la opinión de cirujanos reconocidos en la materia, entre ellos el profesor Ganz; el análisis de bibliografía que estuviera en desacuerdo con los conocimientos clásicos al respecto y el estudio de la irrigación mediante trabajos de disección cadavérica en dos preparados inyectados con látex coloreado. Resultados: La irrigación del acetábulo y la cabeza femoral está dada por un sistema arterial interno y otro externo, que ordena las arterias según su zona de irrigación y no según su origen. Durante la osteotomía periacetabular se lesionan varias de estas arterias. Conclusiones: Los vasos remanentes, asociados fundamentalmente con la prolífica red de anastomosis involucrada, aseguran la irrigación del acetábulo y la cabeza femoral.

Osteotomia periacetabular de Ganz: anatomía vascular en relacion co el acetabulo y la cabeza femoral / Ganz periacetabular osteotomy: vascular anatomy in relation with the acetabulum and femoral head

Introducción: Esta presentación estudia el fundamento vascular de la técnica quirúrgica propuesta por Ganz, evaluando la relación entre esta cirugía y la anatomía vascular del acetábulo y la cabeza femoral. Materiales y métodos: La evaluación se realizó mediante el estudio de la irrigación acetabular en descripciones clásicas sobre el tema; la opinión de cirujanos reconocidos en la materia, entre ellos el profesor Ganz; el análisis de bibliografía que estuviera en desacuerdo con los conocimientos clásicos al respecto y el estudio de la irrigación mediante trabajos de disección cadavérica en dos preparados inyectados con látex coloreado. Resultados: La irrigación del acetábulo y la cabeza femoral está dada por un sistema arterial interno y otro externo, que ordena las arterias según su zona de irrigación y no según su origen. Durante la osteotomía periacetabular se lesionan varias de estas arterias. Conclusiones: Los vasos remanentes, asociados fundamentalmente con la prolífica red de anastomosis involucrada, aseguran la irrigación del acetábulo y la cabeza femoral.(AU)

Capsular and pericapsular contributions to acetabular and femoral head perfusion.

BACKGROUND: Capsular and pericapsular vessels are believed to contribute to acetabular and femoral head perfusion, but, to our knowledge, there is no anatomic study to support this theory. The purpose of this study was to describe the vascular anatomy of the hip with particular reference to the contributions of the capsular and pericapsular vessels. METHODS: Twenty fresh cadavers were dissected twenty-four hours after intra-arterial injection of colored silicone. The arteries supplying the hip were followed by careful dissection from their origins outside the pelvis to their terminal branches. Particular attention was paid to the vessels traveling between the acetabulum and the capsule and the femoral head. RESULTS: In all twenty specimens, the hip capsule received blood supply from the superior and inferior gluteal arteries proximally and from the medial and lateral femoral circumflex arteries distally. The contributory vessels entered the capsule peripherally and superficially. The circumflex arteries supplied the anterior capsule. The gluteal arteries supplied the posterior and posterosuperior aspect of the hip capsule, augmented by contributions from the circumflex arteries. Variable anastomoses were found between the gluteal and femoral systems on the capsular surface beneath the gluteus minimus and short hip external rotators. The medial femoral circumflex artery provided the dominant blood supply to the femoral head in eighteen specimens, and the inferior gluteal artery provided the dominant supply in two specimens. CONCLUSIONS: Capsular and pericapsular vessels that contribute to the blood supply of the acetabulum run on the posterior and posterolateral surface of the capsule. The dominant blood supply to the femoral head comes from vessels that approach the joint posteriorly and penetrate the joint near the femoral attachment of the capsule.

Evaluation of blood loss during limb salvage surgery for pelvic tumours.

As a large amount of blood loss is sometimes encountered in limb salvage procedures for pelvic tumours, it is essential to identify risk factors predicting the possibility of extensive haemorrhage. We retrospectively reviewed 137 patients who underwent pelvic tumour resections. Patients with an estimated blood loss greater than 3,000 ml were classified as having a large amount of blood loss. Sixty-one (44.53%) patients had blood loss greater than 3,000 ml. Tumours involving the acetabulum or sacrum, tumour volume greater than 400 cm(3), aorta occlusion, resection method, reconstruction and operative time were all associated with a large amount of blood loss. Pelvic tumours involving the acetabulum or sacrum (odds ratio: 4.837), tumour volume greater than 400 cm(3) (odds ratio: 3.005) and planned operation time of more than 200 min (odds ratio: 3.784) independently predicted a large amount of blood loss. Pelvic tumours with these characteristics were likely to have a large amount of blood loss during surgery.

The anterolateral approach leads to less disruption of the femoral head-neck blood supply than the posterior approach during hip resurfacing.

In 12 patients, we measured the oxygen concentration in the femoral head-neck junction during hip resurfacing through the anterolateral approach. This was compared with previous measurements made for the posterior approach. For the anterolateral approach, the oxygen concentration was found to be highly dependent upon the position of the leg, which was adjusted during surgery to provide exposure to the acetabulum and femoral head. Gross external rotation of the hip gave a significant decrease in oxygenation of the femoral head. Straightening the limb led to recovery in oxygen concentration, indicating that the blood supply was maintained. The oxygen concentration at the end of the procedure was not significantly different from that at the start. The anterolateral approach appears to produce less disruption to the blood flow in the femoral head-neck junction than the posterior approach for patients undergoing hip resurfacing. This may be reflected subsequently in a lower incidence of fracture of the femoral neck and avascular necrosis.

Corona mortis: an anatomical study with clinical implications in approaches to the pelvis and acetabulum.

The "corona mortis" is an anatomical variant, an anastomosis between the obturator and the external iliac or inferior epigastric arteries or veins. It is located behind the superior pubic ramus at a variable distance from the symphysis pubis (range 40-96 mm). The name "corona mortis" or crown of death testifies to the importance of this feature, as significant hemorrhage may occur if accidentally cut and it is difficult to achieve subsequent hemostasis. It constitutes a hazard for orthopedic surgeons especially in the anterior approach to the acetabulum. We carried out forty cadaver dissections (80 hemi-pelvises) through the ilioinguinal approach. A vascular anastomosis was found in 83% of specimens. Of these, 60% had a large diameter (>3 mm) channel along the posterior aspect of the superior pubic ramus. In clinical practice, however, 492 anterior approaches (to the best of our knowledge the largest series described) have been carried out over the last 15 years by the senior author (MB) and only five of these problematic vessels were discovered, and in only two cases was there troublesome bleeding. This study confirms a paradox: in anatomical dissections a large vessel was identified behind the superior pubic ramus, whereas in clinical practice this vessel does not seem to be as great a threat as initially perceived. Orthopedic surgeons planning an anterior approach to the acetabulum, such as the ilioinguinal or the intrapelvic approach (modified Stoppa), have to be cautious when dissecting near the superior pubic ramus. Despite the high prevalence of these large retropubic vessels in the dissecting room, surgeons should exercise caution but not alter their surgical approach for fear of excessive hemorrhage.