Ilioinguinal Approach to the Acetabulum

Ilioinguinal Approach to the Acetabulum

The ilioinguinal approach allows exposure of the inner surface of the pelvis from the sacroiliac joint to the pubic symphysis (Fig. 7-21). It allows visualization of the anterior and medial surfaces of the acetabulum and is, therefore, suitable for exposure of anterior column fractures of the acetabulum.4 It also allows insertion of screws into the posterior column. The dissection involves isolating and mobilizing the femoral vessels and nerve, as well as the spermatic cord in the male and the round ligaments in the female. Because orthopedic surgeons usually do not operate in this area, operating in conjunction with a general surgeon or as part of an experienced pelvic trauma team is advisable when first using this approach. In addition, cadaveric dissection should be performed before first embarking on this exposure if at all possible.

 

Position of the Patient

 

Place the patient supine on the operating table with the greater trochanter at the edge of the table. This allows the buttock muscles and gluteal fat to fall posteriorly away from the operative plane. Insert a urinary catheter. A full bladder will obscure vision.

 

 

Figure 7-21 The ilioinguinal approach allows access to the anterior column and medial aspect of the acetabulum. It also allows visualization of the inner aspect of the pelvis from the sacroiliac joint to the symphysis pubis. Dark brown shading shows the areas of bone that can be visualized directly. Light brown shading sows those areas of bone that can be palpated.

 

Landmarks and Incision

Landmarks

Palpate the anterior superior iliac spine by bringing your fingers up from below.

Pubic Tubercles

With your fingers anchored on the trochanter, move your thumbs medially along the inguinal creases and obliquely downward until you can feel the pubic tubercle.

Incision

Make a curved anterior incision beginning 5 cm above the anterior superior iliac spine. Extend the incision medially, passing 1 cm above the pubic tubercle to end just beyond the midline (Fig. 7-22).

 

Internervous Plane

There is no true internervous plane. The dissection consists essentially of lifting off muscular, nervous, and vascular structures from the inner wall of the pelvis.

 

Superficial Surgical Dissection

 

Dissect down through the subcutaneous fat to expose the aponeurosis of the external oblique muscle (Fig. 7-23). The lateral cutaneous nerve of the thigh which often consists of multiple branches rather than a single nerve will appear in the lateral edge of the dissection. In many cases, the nerve will need to be divided. Divide the aponeurosis of the external oblique muscle in the line of its fibers from the superficial inguinal ring to the anterior superior iliac spine (Fig. 7-24). This will expose the spermatic cord in the male and the round ligament in the female. Carefully isolate these structures in a sling (Fig. 7-25). Continue the dissection medially, dividing the anterior part of the rectus sheath to expose the underlying rectus abdominis muscle.

 

 

Figure 7-22 Make a curved anterior incision beginning 5 cm above the anterior superior iliac spine. Extend the incision medially, passing just above the pubic tubercle to end in the midline.

 

 

Figure 7-23 Dissect through subcutaneous fat in the line of the skin incision to expose the aponeurosis of the external oblique muscle.

 

Deep Surgical Dissection

 

Divide the rectus abdominis muscle transversely 1 cm proximal to its insertion into the symphysis pubis (Fig. 7-26). Using blunt dissection, develop a plane between the back of the symphysis pubis and the bladder. This space (the Cave of Retzius) is easily developed with a finger (see Fig. 7-11).

Detach those fibers of the internal oblique and transversus abdominis muscles that form the posterior wall of the inguinal canal from the inguinal

ligament leaving 1 to 2 mm of the ligament attached to the muscles to facilitate repair during closure (Fig. 7-27). Take care when approaching the deep inguinal ring; the inferior epigastric artery and vein cross the posterior wall of the canal at the medial edge of the deep inguinal ring and must be ligated at that point. Inadvertent division of these structures results in profuse hemorrhage that is difficult to control (Fig. 7-28).

The peritoneum covered with extraperitoneal fat is now exposed. Using a swab, push the peritoneum upward to reveal the femoral vessels, the femoral nerve, and the iliopsoas (Fig. 7-29). Isolate the femoral vessels together in the femoral sheath and protect them with a sling.

Strip the iliacus muscle from the inside of the wing of the ilium. Initially, you will need to use sharp dissection, but once inside the pelvis use blunt dissection.

The iliopectineal fascia is a thick fascial layer covering the surface of the iliacus muscle. It separates the iliacus muscle with the femoral nerve lying on its surface from the vascular bundle (see Fig. 7-27A,B). Crucially it is attached to the pubic bone. The structure must be identified and divided to allow access to the inner wall of the pelvis, the medial aspect of the acetabulum, and quadrilateral plate. Flex the hip to take tension off the muscle and pass a second sling around the iliopsoas with the femoral nerve lying on top of it. Gently retract these structures laterally and gently retract the vascular bundle medially. Incise the fascia overlying the muscle and develop a plane between the muscle and the fascia (Fig. 7-30). Then divide the fascia down to the pubic bone under direct vision to gain access to the underlying medial surface of the acetabulum and superior pubic ramus (Fig. 7-31).

 

 

Figure 7-24 Divide the aponeurosis of the external oblique muscle from the superficial inguinal ring to the anterior superior iliac spine.

 

Three windows are created. The lateral window, lateral to the iliopsoas gives access to the inner surface of the ilium all the way round to the anterior aspect of the sacroiliac joint (see Anterior Approach to the Sacroiliac Joint). The middle window, medial to the iliopsoas but lateral to the femoral artery and vein gives access to the quadrilateral plate. The medial window, medial to the femoral artery and vein gives access to the superior pubic ramus and symphysis. For best visualization of the medial window, the surgeon should move to stand on the opposite side of the patient (see Anterior Approach to the Sacroiliac Joint). Tilting the

operating table also improves visualization of the medial window. In many patients a retropubic vascular anastomosis exists between the obturator vessels and either the inferior epigastric vessels (corona mortis) or the external iliac vessels. These anastomoses may be inadvertently torn resulting in bleeding that is difficult to control. These anastomoses are most easily seen if the surgeon is standing on the opposite side of the table. If identified, ligate the vessels to permit easier mobilization of the vascular bundle (Fig. 7-32).

 

 

Dang

 

 

Nerves

The femoral nerve runs beneath the inguinal canal lying on the iliopsoas muscle. Take care to avoid vigorous retraction, as stretching the nerve will result in a paralysis of the quadriceps muscle. Flexing the hip will take tension of the iliopsoas and the nerve and make mobilization of these structures much easier.

 

 

Figure 7-25 Mobilize the spermatic cord or round ligament in a sling. The posterior wall of the inguinal canal is now exposed.

 

 

Figure 7-26 Divide the rectus abdominis muscle 1 cm proximal to its insertion into the symphysis pubis.

 

 

 

Figure 7-27 Schematic diagram of inguinal ligament. A: To open up the inguinal canal divide the fascia of the external oblique muscle. B: The inguinal canal has

been opened. The internal oblique and transversus abdominis muscles arise from the inguinal ligament—the rolled-in lower border of the external oblique aponeurosis. C: Detach the internal oblique and the transversus abdominis muscles from the inguinal ligament leaving 2 mm of the ligament attached to the muscles.

 

 

 

Figure 7-28 Ligate and divide the inferior epigastric vessels. Complete the division of the muscular structures of the posterior wall of the inguinal canal.

 

 

Figure 7-29 Using a swab, push the peritoneum upward to reveal the femoral vessels. Mobilize the iliacus muscle from the inner aspect of the ilium. Note the iliopectineal fascia covering the muscle and separating it from the femoral sheath.

 

The lateral cutaneous nerve of the thigh may have to be divided around the anterior superior iliac spine at this stage of dissection. If it is possible to retract it without compromising the exposure, do so. Dividing the nerve will leave a patch of numbness on the outer side of the thigh and patients should be warned that this may occur.

Vessels

The femoral vessels as they pass beneath the inguinal ligament are surrounded by a funnel-shaped fascial covering called the femoral sheath. It is this sheath that should be mobilized and held between slings rather than dissecting out the artery and vein separately. Care should be taken on retraction of these structures to minimize the risk of deep vein thrombosis. The femoral sheath contains the femoral artery and vein, and medial to the

vein is a space known as the femoral canal. The femoral canal contains efferent lymph vessels, but also provides a dead space into which the femoral vein can expand. This space can also, however, contain a femoral hernia, and this should be remembered when mobilizing the structure.

The inferior epigastric artery crosses the operative field passing medial to the deep inguinal ring. It will need to be ligated to allow access to the deeper structures. The inferior epigastric vein may be damaged during dissection at the medial end of the approach. It is usually avulsed from the side of the femoral vein. This causes a profuse hemorrhage and requires the sewing of the resultant vascular defect in the side of the vein.

 

 

 

Figure 7-30 Pass the sling around the femoral sheath. Develop a plane between the iliopsoas muscle and the overlying iliopectineal fascia. Pass a sling around the iliopsoas deep to the iliopectineal fascia.

 

Retro pubic anastomoses exist in some patients between the obturator

vessels and either the inferior epigastric vessels (corona mortis) or the external iliac vessels.5,6 These vessels should be looked for in the medial window and if present ligated to prevent inadvertent rupture during mobilization of the vascular bundle.

 

 

Other Dang

 

 

The spermatic cord contains the vas deferens and testicular artery. Although it is easily mobilized, it must be treated gently during the approach and the closure to avoid ischemic damage to the testicle.

The bladder is easily mobilized off the back of the symphysis pubis. Be aware that fractures of the lower half of the anterior column, especially displaced fracture of the superior pubic rami, may have caused bladder damage and adhesions.

 

How to Enlarge the Approach

Extensile Measures

This approach can be extended proximally to expose the sacroiliac joint. Extend the skin incision posteriorly following the iliac crest. Using sharp dissection, cut down onto the bone. Then strip off the origins of the iliacus from the inside of the ilium using blunt dissection. Retract this iliacus medially to expose the inner wall of the ilium and the sacroiliac joint (see Fig. 7-30).

This approach cannot be extended distally.

 

 

Figure 7-31 Divide the iliopectineal fascia down to the bone to allow access to the medial aspect of the acetabulum. Retract the iliopsoas laterally and the femoral sheath medially to reveal the medial surface of the acetabulum. Retract the femoral sheath laterally to reveal the superior pubic ramus. Retract the iliopsoas medially to reveal the inner surface of the ilium round to the sacroiliac joint.

 

 

Figure 7-32 A: The iliopectineal fascia is a thick fascial layer covering the surface of the iliacus muscle separating the iliacus muscle with the femoral nerve on its surface from the vascular bundle. B: Dividing the iliopectineal fascia allows access to the medial aspect of the acetabulum.

 

Applied Surgical Anatomy of the Ilioinguinal Approach to the Acetabulum

 

 

Overview

 

The applied anatomy of this approach is conveniently divided into two parts.

1. Lateral and posterior to the anterior superior iliac spine. The dissection consists of detaching those muscles that arise from or insert into the iliac crest and the inner wall of the ilium using subperiosteal dissection.

2. Medial and anterior to the anterior superior iliac spine. The applied anatomy of the approach is that of the inguinal canal and its related structures. Because pathology in this area nearly always relates to herniae, both inguinal and femoral, it is usually an unfamiliar ground for orthopedic surgeons and, thus, is potentially hazardous.

 

Landmarks and Incision

Landmarks

The anterior superior iliac spine is the site of attachment to two important

structures. The sartorius takes its origin from it and the inguinal ligament uses it as a lateral attachment.

The anterior third of the iliac crest serves as the origin of the following three muscles.

1. The external oblique forms the outer layer of the muscles of the anterior abdominal wall. It inserts into the outer strip of the anterior half of the iliac crest.

2. The internal oblique forms the middle layer of the muscles of the anterior abdominal wall. It originates from the center strip of the anterior half of the iliac crest.

3. The tensor fasciae latae arises from the outer lip of the anterior half of the iliac crest.

The pubic tubercle is not easily palpated because it is covered by the spermatic cord in the male and the round ligament in the female.

Incision

This curved incision roughly follows the lines of cleavage in the skin. However, the extensive dissections involved may leave rather broad scars. They are nearly always hidden by clothing.

 

Superficial Surgical Dissection and Its Dangers

 

The dissection consists of the division of the fascia of the external oblique muscle and anterior rectus sheath. The external oblique, which is the outer layer of the abdominal muscles, arises from the lower eight ribs. It inserts as fleshy fibers into the anterior half of the iliac crest. However, from the anterior superior iliac spine, it becomes aponeurotic. The aponeurosis attaches to the pubic tubercle and medially becomes fused with the aponeurosis of the opposite external oblique muscle to form the anterior part of the rectus sheath. Therefore, the splitting of the fibers of the external oblique muscle and the incision of the anterior rectus sheath are both in the same plane. There is a free lower border of this muscle between the anterior superior iliac spine and the pubic tubercle. This free edge is called the inguinal ligament. The aponeurosis curls back on itself to form a gutter, and the free edge of this gutter is the origin of part of the internal oblique and transversus abdominis muscles.

Just above the pubic tubercle, there is a gap in this aponeurosis to allow the passage of the spermatic cord in the male and the round ligament in the female. This gap is known as the superficial inguinal ring (Fig. 7-

33). Dividing the fascia of the external oblique opens up the inguinal canal which is an oblique intramuscular slit running from the deep to the superficial inguinal rings. These contain the spermatic cord in the male and the round ligament in the female (Fig. 7-34).

The rectus abdominis muscle is enclosed in a sheath of fascia. In the region of this approach, however, the posterior layer of fascia is absent. The anterior rectus sheath also receives some tissue from both the internal oblique and transversus abdominis muscles.

The spermatic cord consists of the vas deferens accompanied by its artery and the testicular artery and vein. As these structures emerge through the abdominal wall, they get coverings from each layer they pass through (Fig. 7-35). The transversalis fascia covers the cord with a thin layer of tissue known as the internal spermatic fascia. Passing through the transversus abdominis and internal oblique, the cord gets covered with a layer of muscle known as the cremasteric muscle. As it passes through the external oblique at the superficial inguinal ring, it is covered by a thin layer known as the external spermatic fascia. The round ligament in the female is also covered by these three fascial layers. Both the spermatic cord and round ligament can be mobilized easily in the inguinal canal during the superficial surgical dissection.

 

Deep Surgical Dissection and Its Dangers

 

Once the spermatic cord has been mobilized the posterior wall of the inguinal canal is seen. In the lateral half of the inguinal canal, the rolled free edge of the external oblique aponeurosis gives origin to muscle fibers from both the internal oblique and the transversus abdominis. These muscle fibers arch up over the spermatic cord and fuse to form a conjoint tendon that is attached posterior to the spermatic cord into the pubic crest. Therefore, in the medial half of the inguinal canal, its posterior wall consists of this conjoint tendon which needs to be divided for access to the underlying structures. The spermatic cord exits from the abdominal cavity through the deep inguinal ring to enter the inguinal canal. Lateral to the deep inguinal ring, fibers of the internal oblique and transversus abdominis arise from the inguinal ligament and also have to be detached with a small cuff of the ligament to facilitate repair during closure (see Fig. 7-35). Medial to the deep inguinal ring lies the inferior epigastric artery which usually requires ligation. Deep to these muscles lies the thin transversalis fascia, extraperitoneal fat, and finally the peritoneum (Fig. 7-37).

The dissection completely disrupts the anatomy of the inguinal canal. Careful repair of all these structures on a layer-by-layer basis is important to prevent the development of an inguinal hernia.

Passing under the inguinal ligament from the abdomen into the thigh are the femoral nerve, the femoral artery, and the femoral vein, as well as the psoas and iliacus muscles (Fig. 7-36). The iliacus arises from the hollow of the iliac fossa, and runs into the thigh underneath the lateral part of the inguinal ligament. The psoas muscle arises from the anterior aspect of the lumbar spine and passes into the thigh below the middle of the inguinal ligament. Between these two muscles, the femoral nerve runs down into the thigh. It is intimately related to the iliopsoas and is mobilized with the muscle to avoid excessive retraction. Covering the muscle is a thick layer of fascia known as the iliopectineal fascia. This is attached deeply to the pubis and must be divided to allow access to the inner surface of the pelvis. This fascial layer separates the vascular bundle from the iliopsoas (see Fig. 7-29). Medial to the nerve, the femoral artery and vein enter the thigh. As these vessels leave the abdomen, they take with them a fascial layer derived from the extraperitoneal fascia. This is known as the femoral sheath. In addition to the artery and vein, the femoral sheath has a space in it, medial to the vein, known as the femoral canal. The function of the femoral canal is to allow the passage of lymphatic vessels and to make it possible for the vein to expand at times when the blood return from the leg becomes increased.

It is also, however, the site of a femoral hernia. Because the femoral artery and vein are enclosed in a common fascial sheath, they should be mobilized together. Separate mobilization of the femoral vein will traumatize it leading to possible thrombosis.

The bladder is separated from the pubic bones by a space known as the Cave of Retzius. It is occupied by very thin tissue, the bladder, and, in the case of the male, the prostate. The prostate can be easily mobilized from the back of the pubis. However, in cases of fracture, there may be pathologic adhesions in this area, and great care should be taken not to accidentally produce a bladder rupture. A full bladder will make safe access to this area impossible, and a urinary catheter inserted preoperatively is vital (Fig. 7-38).

 

 

Figure 7-33 The superficial musculature of the inguinal region. Just above the pubic tubercle, there is a gap in the aponeurosis of the external oblique to allow the

passage of the spermatic cord in the male and the round ligament in the female. This gap is known as the superficial inguinal ring (inset).

 

 

Figure 7-34 Dividing the external oblique muscle opens up in the inguinal canal. The spermatic cord is revealed covered by the cremasteric muscle, a muscle derived from the internal oblique muscle (inset).

 

 

Figure 7-35 As the testis migrates out through the anterior abdominal wall in fetal development, it and the vas deferens get coverings from each layer they pass

through. The external oblique provides the external spermatic fascia. The internal oblique and the transversus abdominis provide the cremasteric muscle. The transversalis fascia provides the internal spermatic fascia. The cord is retracted to reveal the posterior wall of the inguinal canal formed by the conjoint tendons (inset).

 

 

Figure 7-36 Deep to the inguinal ligament run the femoral nerve, the femoral vessel, as well as the psoas and iliacus muscles. Medial to the deep inguinal ring lie the inferior epigastric vessels (inset).

 

 

Figure 7-37 Division of the posterior wall of the inguinal canal reveals the extraperitoneal fat.

 

 

 

Figure 7-38 The medial aspect of the acetabulum can be exposed by retraction of the iliopsoas and the femoral sheath. The inner aspect of the superior pubic ramus can only be visualized by careful mobilization of the bladder.