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Pelvis and Acetabulum
Anterior Approach to the Iliac Crest for Bone Graft Posterior Approach to the Iliac Crest for Bone Graft Anterior Approach to the Pubic Symphysis
Anterior Approach to the Sacroiliac Joint Posterior Approach to the Sacroiliac Joint Applied Surgical Anatomy of the Bony Pelvis Ilioinguinal Approach to the Acetabulum
Applied Surgical Anatomy of the Ilioinguinal Approach to the Acetabulum
Posterior Approach to the Acetabulum
The pelvis is a complex bony structure with interconnecting ligaments. It consists of the two innominate bones, which articulate anteriorly with each
other at the pubic symphysis and posteriorly with the body of the sacrum at the sacroiliac joint. The bones are covered on each side by muscles, and the intra-abdominal contents make surgical exposure potentially complex. The presence of a large subcutaneous surface (the iliac crest), however, allows safe access to the ilium.
Five approaches to the pelvis are described in this chapter, all of which provide access to the bone via its subcutaneous portion. The anterior and posterior approaches to the iliac crest are used almost exclusively for bone grafting. The anterior approach to the pubic symphysis and the anterior and posterior approaches to the sacroiliac joints are performed rarely; their use is associated almost exclusively with the open reduction and internal fixation of pelvic ring fractures.
Approaches to the acetabulum are the most complex and demanding approaches a surgeon can be asked to perform. They are nearly always used for the reconstruction of the acetabulum following fractures. Because each approach only gives access to a limited part of the acetabulum, it is critically important that the correct approach is used for each fracture pattern (Fig. 7-1). This requires accurate assessment of the anatomy of the fracture, using radiographic techniques, including computerized tomography.1–3 The use of a bone model is invaluable especially when a surgeon is inexperienced.
The ilioinguinal approach to the acetabulum 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. It does not allow direct access to the posterior column or posterior lip (see Fig. 7-21).
Figure 7-1 To appreciate the anatomy of the anterior and posterior columns of the acetabulum, hold a hemipelvis up against a light source. These two massive columns can then be appreciated in contrast to the thin central area of the wing of the ilium.
The posterior approach to the acetabulum allows access to the posterior column, posterior lip, and dome segment of the acetabulum. It allows very limited access to the anterior column of the acetabulum and no access to the medial aspect of the acetabulum (see Fig. 7-39).
The applied surgical anatomy of the ilioinguinal approach is to be found immediately after the description of the surgical approach. The applied surgical anatomy of the posterior approach is found in Chapter 8 (see page 451).
Because each approach only provides limited access to the acetabulum complex fractures may require the use of more than one approach.
Most acetabular fractures occur as a result of extremely violent trauma.
The tissues therefore are contused and muscle planes are often difficult to develop. The fractures themselves are difficult to reduce, and control and specialized instruments are necessary to ensure anatomical reduction and stable fixation. There is rarely, if ever, an indication to perform these approaches in an emergency situation. Acetabular fractures are rare. Understanding of the anatomy of the fracture is difficult and surgical approaches are technically demanding. The results of acetabular reconstruction depend largely on the accuracy of the reduction of the fracture. For these reasons, acetabular surgery, if at all possible, should be performed by experienced surgeons working in centers large enough to attract a sufficient volume of patients.
Anterior iliac crest bone grafts are the most commonly used grafts in orthopedic surgery. The iliac crest is subcutaneous, and cortical, cancellous, or corticocancellous grafts can be taken from it with ease and safety for grafting in all parts of the body including the spine. It also is possible to remove pieces of the iliac crest, including both cortices, for major bone reconstructions, especially in the head and neck. For posterior spinal fusion work on conditions such as scoliosis, the bone graft usually is taken from the posterior aspect of the iliac crest.
Position of the Patient
Place the patient supine on the operating table. Because the graft is usually taken in conjunction with other procedures, the iliac crest should be draped as a separate unit. There is much to be said for preparing this area routinely in all cases of open reduction and internal fixation of long-bone fractures. Place a small sandbag under the gluteal (cluneal) area of the side from which the graft will be taken to elevate the crest and rotate it internally, making it more accessible.
Landmarks and Incision
The subcutaneous anterior superior iliac spine, the most important
landmark, is easily palpable. Continue palpating along the crest of the ilium until its widest portion is reached, at the iliac tubercle. The iliac tubercle marks the area of the ilium containing the largest amount of cortical cancellous bone for graft material.
Internervous Plane
Muscles either take origin from or insert onto the iliac crest, but do not cross it. Therefore, the crest offers a truly internervous plane.
The tensor fasciae latae, gluteus minimus, and gluteus medius are the muscles affected most directly by grafts taken from the anterior portion of the crest, because they originate from the outer portion of the ilium and are supplied by the superior gluteal nerve. The abdominal muscles take their origin directly from the iliac crest and are supplied segmentally.
Superficial Surgical Dissection
Retract the skin and identify the iliac crest. Cut down onto the iliac crest with a scalpel (Fig. 7-3). In children, the crest still may be an avascular apophysis. If so, incise it and remove the muscle through the crest in either direction with a Cobb elevator. No apophysis will be present in adults.
Take care not to carry the incision from the apophysis or iliac crest onto the anterior superior iliac spine itself; if this occurs, the origin of the inguinal ligament may be detached and an inguinal hernia may result.
Deep Surgical Dissection
The muscles may be stripped off either the inner or the outer wall of the ilium. Initially, cut down onto the bone using a scalpel. Follow the contour of the bone, sticking to it rigidly (Fig. 7-4). Below the crest itself, the ilium narrows considerably, so the sharp dissection will need to follow the contour of the bone carefully to avoid straying out of plane and into trouble. After coming around the corner of the crest onto the ilium, continue the dissection using blunt instruments such as a Cobb elevator. The muscles will come away from the bone easily. Alternatively, push a
swab into the plane between the iliac wing and the overlying muscles. Using a blunt instrument introduce more and more of the swab into the plane. The swab will act as a tissue expander, pushing the muscle away from the bone, while at the same time protecting the soft tissues. Corticocancellous strips may be taken from either side of the bone, or a complete block of the ilium can be removed. Pure cancellous bone can be taken by elevating a small piece of the cortex of the crest. Be aware that the largest supply of cancellous bone is directly underneath the subcutaneous surface of the crest.
Figure 7-2 Make an 8-cm incision parallel to the iliac crest and centered over the iliac tubercle.
Both the crest of the ilium and the anterior superior iliac spine should be left intact to preserve the normal appearance of the pelvis. If the anterior
How to Enlarge the Approach
Place a sharp-tipped retractor onto the bone to retract either the gluteal muscles from the outer cortex or the iliacus muscle from the inner cortex. Placing a swab between the retractor and the muscles creates a bloodless field and prevents little pieces of bone graft from being lost in the depth of the wound. Great care must be taken, however, to remove this swab before undertaking closure. The incision may have to be lengthened on the iliac crest and additional amounts of gluteus medius or iliacus stripped off to provide a better view of the outer or inner cortex of the anterior portion of the ilium.
This approach is not classically extensile. The approach described in this section is merely a means of obtaining bone graft.
Figure 7-3 Retract the skin, identify the iliac crest, and incise the soft tissues overlying the iliac crest down to bone.
Figure 7-4 Remove the origins of the gluteus minimus and medius muscles subperiosteally from the outer cortex of the ilium.
Posterior iliac crest bone grafts usually are taken during any posterior spine surgery that requires additional autogenous bone to supplement the area to be fused. The grafts also may be used as corticocancellous grafts for any part of the skeleton that needs fusion or refusion.
Position of the Patient
Place the patient prone on the operating table, with bolsters running
longitudinally to support the chest wall and pelvis, allowing the chest wall and abdomen to expand without touching the table. Place drapes distally enough so that the beginning of the gluteal cleft and the posterior superior iliac spine can be seen (see Fig. 6-101).
Landmarks and Incision
Palpate the posterior superior iliac spine under the dimpling of the skin above the buttock. The subcutaneous posterior part of the iliac crest also is palpable.
Make an 8-cm oblique incision centered over the posterior superior iliac spine and in line with the iliac crest (Fig. 7-5, inset).
If scoliosis surgery or lumbar surgery is being performed, the midline incision can be extended distally to the sacrum. Then, the skin and a thick, fatty, subcutaneous layer can be retracted laterally. Using a Hibbs retractor dissect the flap free from the underlying lumbodorsal fascia until the posterior superior iliac spine and crest can be palpated and seen (see Fig. 7-5).
Internervous Plane
Muscles insert into or take origin from the iliac crest, but do not cross it. Therefore, the outer border of the iliac crest is truly an internervous plane. The gluteus medius, minimus, and maximus muscles take their origins from the outer surface of the ilium (the gluteus medius and minimus are supplied by the superior gluteal nerve and the gluteus maximus is supplied by the inferior gluteal nerve). The segmentally supplied paraspinal muscles take their origin from the iliac crest itself, as does the latissimus dorsi, which is supplied proximally by the long thoracic nerve. Thus, an incision into the iliac crest does not denervate muscles, even if it is not placed exactly on the outer lip of the crest.
Figure 7-5 If lumbar spine surgery is being performed, extend the midline incision distally, retracting the skin laterally until the posterior superior iliac spine and crest can be palpated and seen. Incise the soft tissues overlying the crest down to bone. Make an 8-cm oblique incision, centered over the posterior superior iliac spine and in line with the iliac crest (inset).
Superficial Surgical Dissection
Incise the subcutaneous tissues in the line of the skin incision until the iliac crest is reached. In children, the iliac apophysis is white and quite visible; it may be incised or split in line with the iliac crest, using it as an avascular plane. In adults, the apophysis is ossified and fused to the crest; the incision lands directly on the crest itself.
Use a Cobb elevator to remove the apophysis or muscles from the iliac
crest both medially and laterally, to bare the surface of the posterior portion of the crest.
The cluneal nerves cross the iliac crest. They can be avoided by placing the incision no more than 8 cm anterolateral to the posterior superior iliac spine. The nerves supply sensation to the skin over the cluneal (gluteal) area. They are composed of the posterior primary rami of L1, L2, and L3. Their loss does not cause problems for the patient.
Deep Surgical Dissection
Strip the musculature completely off the posterior portion of the lateral surface of the ilium so that a large enough graft can be obtained. Take care to stay in a subperiosteal plane while passing from the iliac crest to the outer cortex of the ilium. Proceeding 1.5 cm down the ilium in the area of the posterior superior spine, the elevated posterior gluteal line can be seen and felt; pass subperiosteally up over the line and then down its other side. Do not err by letting the line direct the incision outward from bone into muscle. A Taylor retractor will help the exposure by holding the muscles laterally. Note that the posterior gluteal line separates the origins of the gluteus maximus (posterior) from the gluteus medius (anterior; Fig. 7-6).
It is remotely possible that an osteotome will hit the sciatic nerve, which runs close to the distal end of the wound deep to the sciatic notch; however, if an imaginary line is drawn from the posterior superior iliac spine perpendicular to the operating table, and all work is performed cephalad to it, both the notch and the nerve will be avoided completely. If a larger graft is necessary, palpate the sciatic notch itself before taking the graft (see Fig. 7-6B).
Figure 7-6 A: Subperiosteally strip the musculature off the posterior portion of the lateral surface of the ilium. B: Proceeding down the outer surface of the ilium in the area of the posterior superior spine, the elevated posterior gluteal line can be seen and felt; pass subperiosteally up and over the line and then down its other side. Do not err by letting the line direct you outward from bone to muscle. If you draw an imaginary line from the posterior superior iliac spine perpendicular to the operating table and stay cephalad to it, you will avoid the sciatic notch and its contents.
The superior gluteal vessel, a branch of the internal iliac (hypogastric) artery, leaves the pelvis via the sciatic notch, staying against the bone and proximal to the piriformis muscle. If a graft is taken too close to the sciatic notch, the vessel may be cut and may retract into the pelvis. Nutrient vessels from the artery supply the iliac crest bone along the midportion of the anterior gluteal line, and the vessel may become an osseous bleeder as it enters bone via the nutrient foramen. To control bone bleeding, use bone wax on the raw cancellous surface of the pelvis after the graft has been removed.
How to Enlarge the Approach
Place a sharp-tipped, right-angled Taylor retractor into the bone to retract the gluteal muscles away from the bone and increase the exposure. To increase the exposure further, lengthen the iliac crest incision and strip more of the gluteal muscles from the outer cortex to avoid working through a “keyhole.”
This incision cannot be extended. It is designed specifically for removing bone for graft material from the posterior outer cortex of the ilium. Inner cortex also may be taken, but soft tissues should not be stripped off the anterior (deep) aspect of the ilium.
The anterior approach to the pubic symphysis is an approach that is used almost exclusively for the open reduction and internal fixation of a ruptured symphysis or internal fixation of displaced fractures of the superior pubic ramus. Other uses include biopsy of tumors and treatment of chronic osteomyelitis.
Because widely displaced symphysis injuries often are associated with urologic damage, obtaining a urologic assessment is advisable before undertaking open surgery, which often includes a retrograde urethrogram. A urethral catheter must be inserted before surgery. A full bladder will seriously interfere with the surgical approach.
Position of the Patient
Place the patient supine on the operating table.
Landmarks and Incision
The superior pubic ramus and pubic tubercles are easily palpable in all but the most obese patients. The pubic symphysis will be palpable (as a gap) only in cases of rupture.
Internervous Plane
An internervous plane is not available for use in this approach. Because the rectus abdominis muscles receive a segmental nerve supply, they are not denervated, even though they are divided by this approach.
Figure 7-7 Palpate the pubic tubercles. Make a curved incision in the line of the skin crease, centering it 1 cm above the pubic symphysis.
Superficial Surgical Dissection
Incise the subcutaneous fat in the line of the skin incision, deepening the incision down to the anterior portion of the rectus sheath (Fig. 7-8). Identify, ligate, and divide the superficial epigastric arteries and veins that run up from below across the operative field. Then, divide the rectus sheath transversely, about 1 cm above the symphysis pubis. The two rectus abdominal muscles now are visible (Fig. 7-9). In most cases of rupture of
Deep Surgical Dissection
Retract the cut edges of the rectus abdominal muscles superiorly to reveal the symphysis and pubic crest (Fig. 7-10). If access to the back of the symphysis is required, use the fingers or a swab to push the bladder gently off the back of the bone. Palpation of the posterior surface of the body of the pubis is useful to identify the correct direction for the insertion of screws. This dissection is very easy to perform unless adhesions have formed due to damage to the bladder. Such adhesions make it difficult to open up this potential space (the preperitoneal space of Retzius) (Fig. 7-11). The pubic symphysis and superior pubic rami now are exposed adequately for internal fixation.
The bladder may have been damaged during the trauma. If so, adhesions will have developed between the damaged bladder and the back of the pubis. Mobilization of the space of Retzius, therefore, may lead to inadvertent bladder rupture. If fixation is considered in the presence of urologic damage, it is best to operate in conjunction with an experienced urologic surgeon.
Figure 7-8 Incise the fat in the line of the skin incision and retract the skin edges to reveal the anterior portion of the rectus sheath.
Figure 7-9 Divide the rectus sheath transversely 1 cm above the symphysis pubis to reveal the rectus abdominis muscles and pyramidalis.
How to Enlarge the Approach
Because of the considerable amount of subcutaneous fat in this area, it may be necessary to extend the skin incision and superficial dissection in both directions to allow better visualization of the deep structures in obese patients.
The approach can be extended laterally to expose the entire anterior column of the acetabulum and the inner wall of the ilium. (See ilioinguinal approach to acetabulum, page 378.)
Figure 7-10 Divide the rectus muscles 1 cm above their insertion and retract their cut edges superiorly to reveal the superior ramus of the pubis.
Figure 7-11 A: Open the plane behind the symphysis pubis, using your finger as a blunt dissector. B: The pubic symphysis and superior pubic rami now are exposed.
Anterior Approach to the Sacroiliac Joint
The anterior approach to the sacroiliac joint offers safe, reliable access to that structure and allows anterior plates to be positioned accurately across the joint. It also permits the exposure of the inner wall of the ala of the ilium, allowing fixation of associated iliac fractures. Paradoxically, although the sacroiliac joint is one of the most posterior structures in the entire pelvic ring, the anterior approach allows greater exposure and
control than does the seemingly more logical posterior approach, because of the shape of the joint. Anteriorly, the joint is flat and directly available, whereas posteriorly it is overhung by the posterior iliac crest.
Position of the Patient
Place the patient in a supine position on the operating table and put a large sandbag under the buttock. This will push the iliac crest up toward the surgeon. Support the opposite iliac wing with a support attached to the operating table and then tilt the table 20 degrees away, allowing the mobile contents of the pelvis to fall away.
Landmarks and Incision
The anterior superior iliac spine and the anterior third of the iliac crest are subcutaneous and easy to palpate.
Make a long, curved incision over the iliac crest, beginning 7 cm posterior to the anterior superior iliac spine (at about the level of the iliac tubercle). Curve the incision forward until the anterior superior iliac spine is reached. Continue the incision anteriorly and medially along the line of the inguinal ligament for an additional 4 to 5 cm (Fig. 7-12).
Internervous Plane
No true internervous plane is available for use. The approach consists simply of stripping muscles off the inner side of the pelvis; because the bone is being approached via its subcutaneous surface, no muscle is denervated.
Superficial Surgical Dissection
Deepen the skin incision through the subcutaneous fat onto the subcutaneous surface of the iliac crest. Two techniques can be used to detach the iliacus from the deep surface of the iliac wing.
Bone block technique. Expose the deep fascia overlying the glutei and tensor fasciae latae muscles at the point where it attaches to the outer lip of the iliac crest. Incise the periosteum of the entire anterior third of the
iliac crest and gently strip the muscles off the outer wall of the pelvis to expose about 1 cm of the outer surface below the crest of the ilium.
Predrill the iliac crest for easy reattachment. Using an oscillating saw, transect the wing of the ilium at this level, cutting only the outer cortex and the cancellous bone underneath (Fig. 7-13). Next, crack the inner cortex with an osteotome. This allows the anterior superior iliac spine to be detached along with the transected portion of the iliac wing (Fig. 7-14).
Figure 7-12 Make a curved incision over the iliac crest, beginning 7 cm posterior to the anterior superior iliac spine.
Soft tissue release only. Start just posterior to the anterior superior iliac spine and detach the iliacus muscle and its overlying fascia from the
deep surface of the iliac wing. Begin by using sharp dissection and then develop the plane using a swab used as a tissue expander.
Deep Surgical Dissection
The iliacus muscle arises from the inner wall of the ilium; detach it by blunt dissection. If the bone block technique is used as the dissection is deepened, the detached anterior superior iliac spine, which still is attached to the lateral end of the inguinal ligament, must be mobilized. This block of bone and muscle must be moved medially; to accomplish this, divide some fibers of both the tensor fasciae latae and sartorius muscles (Fig. 7-15). Note that the lateral cutaneous nerve of the thigh is about 1 cm distal and medial to the anterior superior iliac spine, and may have to be divided to permit this mobilization.
Remaining strictly in a subperiosteal plane, strip the iliacus muscle off the inner wall of the pelvis to expose the underlying sacroiliac joint (see Fig. 7-15). The distance is surprisingly short. As the muscle is stripped off, some nutrient vessels will have to be detached from the inner wall of the pelvis. Bleeding usually can be controlled by bone wax.
The L4, L5 nerve roots and the lumbosacral trunk run along the anterior surface of the sacrum approximately 1.5 cm medial to the sacroiliac joint. Therefore do not continue the dissection more than 1.5 cm medial to the sacroiliac joint. If a standard 3.5 mm plate is used to stabilise the joint place the plate so that only one screw hole is placed medial to the joint. Using two holes of the same plate will endanger the nerve root (see Fig. 7-15, inset).
Mobilizing the iliacus muscle off the inside of the pelvis with a large bone block allows the muscles to be reattached securely with screws during closure. The muscle then resumes its anatomic position, and the dead space beneath it is obliterated. If the bone block technique is used, failure to securely reattach the iliac crest will produce impaired function, a poor cosmetic result, possible chronic pain, and a high risk of hematoma formation.
Figure 7-13 Strip the muscles from the outer wall of the pelvis. Predrill the iliac crest. Divide the outer cortex 1 cm below the crest using an oscillating saw.
The lateral cutaneous nerve of the thigh may have to be divided during the mobilization of the anterior superior iliac spine. This will cause some
numbness of the lateral aspect of the thigh. Even if the nerve is not transected a neurapraxia due to retraction is common and patients should be warned that an area of numbness on the lateral aspect of the thigh may occur following surgery that in some cases may be permanent.
The L4, L5 nerve roots and the lumbosacral trunk crosses the anterior surface of the sacrum approximately 1.5 cm medial to the sacroiliac joint. If plates are applied too far medially on the sacrum the nerve will be damaged. This nerve root marks the medial limit of the approach.
The sacral nerve roots can be damaged at the point where they arise from the sacral foramina. For this reason, the dissection cannot be carried further medially than the sacral foramina. The sacral nerve roots are not usually exposed during this approach. They can be at risk at two stages of the operation. If sharp pointed retractors such as Hohmann are used medially, great care should be taken that the point of these retractors is not inadvertently inserted into a sacral foramen. Sacral nerve roots can also be entrapped under the medial end of plates applied to the anterior surface of the sacroiliac joint. Meticulous preoperative planning will allow you to know exactly how many screw holes can be inserted safely into the sacrum without endangering the sacral nerve roots. In most cases, only one screw can be inserted.
Figure 7-14 Crack the inner cortex using an osteotome to complete the iliac osteotomy.
Relatively large nutrient vessels often are avulsed from the inner wall of the ilium. Bleeding from these vessels can be controlled by pressure or bone wax.
How to Enlarge the Approach
Paradoxically, the key to adequate exposure of the posteriorly placed sacroiliac joint is adequate anterior dissection. The lateral end of the inguinal ligament and its attached anterior superior iliac spine must be mobilized to visualize the sacroiliac joint adequately.
The approach may be enlarged into an extended ilioinguinal approach that provides access to the entire anterior column of the acetabulum. This approach is discussed later in this chapter (page 378).
Figure 7-15 Strip the iliacus from the inner wall of the pelvis to expose the underlying sacroiliac joint.
The posterior approach to the sacroiliac joint is a simple, safe approach that does not endanger any vital structures. Its uses include open reduction and internal fixation of disruptions of the sacroiliac joint, open reduction
and internal fixation of fractures of the ilium near the joint, and treatment of infections of the sacroiliac joint or surrounding bones. The popularity of this approach has diminished with the increasing use of percutaneous screw fixation techniques. It is still, however, invaluable if adequate imaging is not possible or if alternative techniques, such as plating, are used.
It should be noted that reduction of fractures and dislocations is difficult through this approach, especially the correction of vertical displacement. Vertical displacement should be corrected by longitudinal traction, preferably preoperatively.
Achieving fixation of these fractures is technically demanding because of the shape of the joint and the presence of the sacral nerve roots arising from the sacral foramina. Practice the direction of screw placement on a bone model before surgery is attempted. During surgery, strict radiologic control of screw fixation using two-plane C-arm imaging is mandatory. Safe screw fixation can also be facilitated by the use of computer-assisted surgery, if such technology is available to the operating surgeon.
Position of the Patient
Place the patient prone on the operating table. Position bolsters longitudinally to support the chest wall and pelvis; the bolsters should allow the chest wall and abdomen to expand without touching the table. Take great care during preparation and draping to exclude the contaminated anal region from the operative field.
Landmarks and Incision
Palpate the subcutaneous posterior iliac crest which terminates in the posterior superior iliac spine.
Figure 7-16 Make a curved incision, beginning 3 cm distal and lateral to the posterior superior iliac spine. Cross the posterior superior iliac spine and continue along the crest to its highest point.
Make a curved incision overlying the posterior iliac crest, beginning 3 cm distal and lateral to the posterior superior iliac spine. Extend the incision
Internervous Plane
No internervous plane is available for use. Both the gluteus maximus and gluteus medius muscles must be detached partially from their origins, but their individual neurovascular pedicles are preserved easily.
Superficial Surgical Dissection
Divide the subcutaneous tissues in line with the skin incision. Anteriorly, small cutaneous nerves (the superior cluneal nerves) may have to be cut, but they are of little clinical significance. Cut down into the outer border of the subcutaneous surface of the iliac crest to reveal the layer of fascia that covers the gluteus maximus muscle. Detach the origin of the gluteus maximus from the crest and carefully reflect the muscle downward and laterally (Fig. 7-17). Two vital structures penetrate this muscle from its deep surface. First, branches from the inferior gluteal artery, which emerges from the pelvis, with the piriformis muscle through the greater sciatic notch, penetrate the muscle. In addition, the inferior gluteal nerve emerges through the notch beneath the piriformis to supply the muscle. Because it is imperative that these two structures be preserved, they limit the inferior mobilization of the muscle. As the gluteus maximus muscle is reflected, the gluteus medius and piriformis muscles will be uncovered.
Figure 7-17 Divide the subcutaneous fat and reflect the skin flap to reveal the fascia overlying the gluteus maximus and gluteus medius.
Deep Surgical Dissection
Gently elevate the gluteus medius muscle from the outer wing of the ilium. The muscle cannot be elevated much because its deep surface is tethered by its neurovascular bundle—the superior gluteal nerves and vessels (Fig. 7-18). In cases of trauma, the ruptured sacroiliac joint or fracture is easily visible but reduction is extremely difficult. To evaluate any reduction, detach part of the origin of the piriformis muscle from around the greater sciatic notch and insert a finger through the notch to palpate the joint from its anterior surface. The surface of the joint will feel smooth if it has been reduced (Fig. 7-19).
The inferior gluteal nerve enters the deep surface of the gluteus maximus muscle. Overzealous downward retraction of the muscle can cause a traction injury to this nerve.
The superior gluteal nerve enters the deep surface of the gluteus medius muscle. This limits the forward retraction of this muscle, restricting the exposure of the outer wing of the ilium. Excessive retraction of the muscle will injure the superior gluteal nerve.
The sacral nerve roots are not endangered by the surgical approach but can be injured by inaccurate screw fixation across the sacroiliac joint. Accurate x-ray control of screw placement is mandatory.
Branches of the superior and inferior gluteal arteries run with their respective nerves and also are in danger.
Figure 7-18 Reflect the gluteus maximus muscle and the gluteus medius from the outer surface of the pelvis.
How to Enlarge the Approach
There are no local measures for enlarging this approach.
Extend the skin incision anteriorly and elevate the gluteus medius and gluteus minimus muscles from the outer surface of the iliac wing. This will enable more extensive fractures of the wing and the ilium to be dealt with. It should be noted that anterior approaches give much better exposure of these structures (see ilioinguinal approach, page 378).
Figure 7-19 Detach part of the origin of the piriformis and insert a finger through the greater sciatic notch to palpate the sacroiliac joint from its anterior surface.
Overview
The approaches described in this chapter obtain access via a subcutaneous portion of the bony pelvis. Thereafter, access is afforded by stripping the muscular coverings off the bone while remaining in a strictly subperiosteal plane. Using this technique, the approaches avoid vital structures and, therefore, are extremely safe. The further one proceeds from a
subcutaneous part of the bone the more muscles must be stripped and the view obtained inevitably becomes poorer. For this reason, these approaches are limited in the exposure they provide. They cannot be extended and afford only limited access to certain portions of the bony skeleton.
Two superficial parts of the innominate bones are used for access. The iliac crest has the internal oblique and transversus abdominis muscle arising from its surface and the external oblique muscle inserting into it. The wing of the ilium itself is sandwiched between two masses of muscles, the glutei and tensor fasciae latae muscles on the outer side, and the iliacus muscle on the inner side. The pubic tubercles and upper parts of the superior pubic rami have the rectus abdominis muscle attached to them, and these must be detached for access to the superior surface of the structures.
Landmarks and Incisions
The anterior superior iliac spine is the site of insertion of the inguinal ligament and the sartorius muscle. The anterior third of the iliac crest is the site of origin for the external oblique, transversus abdominis, and tensor fasciae latae muscles.
The posterior iliac crest is easily palpable and is the site of origin of the external oblique muscle. The posterior superior iliac spine is marked by an overlying dimple. A line connecting these dimples crosses the sacroiliac joint at the level of S2. The pubic tubercle is the medial attachment of the inguinal ligament and the most lateral part of the body of the pubis.
All the incisions described roughly parallel the lines of cleavage. Scars can be broad and ugly, however, but this rarely is of clinical significance because they usually are covered with clothing.
Superficial Surgical Dissection
In all approaches, superficial surgical dissection consists of incising down onto the superficial portion of the bone. In the iliac crest, this merely involves dividing the overlying fat. In the symphysis pubis, the rectus sheath must be opened. The rectus sheath is a tough fibrous structure derived from all three muscles of the anterior abdominal wall. The superior
part of the rectus is enclosed by the sheath. 2 cm below the umbilicus the posterior portion of the sheath formed by the aponeurosis of the internal oblique muscle and the transversus abdominis ceases and the sheath which receives contributions from all three layers of the abdominal wall is only present anterior to the muscle. It forms a tough anterior covering to the underlying rectus muscle which is easy to repair (see Fig. 7-9).
Deep Surgical Dissection
Muscles can be stripped safely off both aspects of the anterior third of the iliac crest, but only from the outer aspect of the posterior third of the crest.
Dissection of the outer side of the ilium involves detaching the origin of the tensor fasciae latae. Covering this muscle is a thick layer of fascia that is continuous with the fascia covering the gluteus maximus muscle. The tensor fasciae latae, gluteus maximus, and the fascia can therefore be thought of as the outer layer of the buttock anatomy (Fig. 7-20). This is analogous to the position of the deltoid muscle in the shoulder. Deep to the structures are the origins of the gluteus medius and gluteus minimus muscles from the outer wing of the ilium. These can be lifted off the bone entirely to provide a view of the wing of the ilium. It is important to realize, however, that the rectus femoris muscle still remains between the surgeon and the hip joint, thus limiting the approach.
Figure 7-20 The superficial musculature of the posterior approach to the hip joint. The gluteus maximus predominates.
Gluteus Maximus. Origin. From posterior gluteal line of ilium and that portion of the bone immediately above and behind it; from posterior surface of lower part of sacrum and from side of coccyx; and from fascia covering gluteus medius. Insertion. Into iliotibial band of fascia lata and into gluteal tuberosity. Action. Extends and laterally rotates thigh. Nerve supply. Inferior gluteal nerve.
The inner surface of the ilium serves as origin for the iliacus muscle. This can be lifted off the bone safely, providing access down to the brim of the true pelvis.
The sacroiliac joint is a paradox. It is a true synovial joint, yet any movement is very difficult to demonstrate. The joint is reinforced heavily by anterior and posterior supporting ligaments. Approached from the front, the sacroiliac joint is perpendicular to the plane of dissection. Approached from the rear, the joint is overhung by the posterior iliac crest, making it oblique to the plane of dissection. It is critically important to appreciate this obliquity when planning the insertion of any screws that may be used to cross the joint.
In contrast, the pubic symphysis is not a synovial joint, but a secondary cartilaginous joint. Its superior surface is readily accessible once the insertion of the rectus abdominis muscle has been detached. Behind the symphysis pubis is a potential space filled with loose areolar tissue; this is known as the cave of Retzius. This potential space lies between the symphysis pubis and the bladder, and allows access to the inner surface of the pubis down to the muscles of the pelvic floor.
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
Palpate the anterior superior iliac spine by bringing your fingers up from below.
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.
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).
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.
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.
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
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.
Overview
The applied anatomy of this approach is conveniently divided into two parts.
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.
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
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.
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.
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.
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
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
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
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.
Posterior Approach to the Acetabulum
The posterior approach gives access to the posterior wall of the acetabulum and its posterior column (Fig. 7-39). It also allows direct visualization of the dorsocranial part of the acetabulum, either through the fracture gap or via a capsulotomy. It is by far the easiest of all acetabular approaches, and extensive blood loss is not usually encountered. The approach also allows access to the anterior column if a trochanteric osteotomy and surgical dislocation of the hip is performed.7,8
Its uses include reduction and fixation of:
Fractures of the posterior lip of the acetabulum
Fractures of the posterior lip and posterior column
(Juxta- and infratectal) Simple transverse fractures
Transverse fractures with associated posterior lip fractures
If a trochanteric osteotomy and surgical dislocation of the hip is used, it can also be used for anterior lip fractures, dome fractures, and acetabular fractures in association with femoral head fractures.
Position of the Patient
Two positions are possible. If the approach is to be used for fractures of the posterior lip and/or posterior column, place the patient in the lateral position. This position is also used if a trochanteric osteotomy is planned.
Alternatively, if the approach is to be used for transverse fractures, place the patient in the prone position (Fig. 7-40). If traction is to be used, place a skeletal pin transversely through the lower end of the femur with the knee flexed to reduce the risk of a traction injury to the sciatic nerve.
Figure 7-39 The posterior approach to the acetabulum allows access to the posterior column, posterior lip, and dome segment of the acetabulum.
With the patient in the lateral position, there is a natural tendency for the femoral head to move medially in cases of transverse acetabular fracture. Operating in the lateral position, therefore, makes reduction of these fractures more difficult. Reduction of the fracture in this position can only be obtained by an assistant lifting the femoral head out of the acetabulum. The use of the prone position facilitates reduction of transverse fractures.
Landmarks and Incision
Palpate the greater trochanter on the outer aspect of the thigh. Note that the posterior edge is easier to palpate than the anterior one.
Internervous Plane
There is no true internervous plane in this approach. However, the gluteus maximus that is split in the line of its fibers is not significantly denervated because it receives its nerve supply well proximal to the split.
Superficial Surgical Dissection
Deepen the incision through subcutaneous fat. Incise the fascia lata in the line of the skin incision in the lower half of the wound, and extend this incision superiorly along the anterior border of the gluteus maximus muscles (Fig. 7-42). Retract the split edges of the fascia to reveal the piriformis muscle and the short external rotators of the hip (Fig. 7-43). Partial detachment of the insertion of gluteus maximus from the femur will facilitate mobilization of this muscle.
Figure 7-40 Position of the patient for posterior approach to the acetabulum. Position of the patient for posterior approach to the acetabulum if a trochanteric flip osteotomy is not to be used. Note the flexed position of the knee to prevent stretching of the sciatic nerve.
Figure 7-41 Make a longitudinal incision centered on the greater trochanter extending from just below the iliac crest to 10 cm below the greater trochanter.
Figure 7-42 Incise the fascia lata in line with the skin incision. Extend the incision superiorly along the anterior border of the gluteus maximus muscle.
Figure 7-43 Retract the split edges of the fascia to reveal the piriformis muscle and the short external rotators of the hip.
Deep Surgical Dissection
Internally rotate the leg to put the short external rotators and the piriformis on the stretch. Identify the quadratus femoris muscle and superior to this the tendon of obturator internus with the accompanying gemelli muscles. Finally identify the piriformis muscle and tendon lying above the superior gemellus. Palpate the sciatic nerve as it runs down the leg lying on the short external rotator muscles and trace the nerve proximally. It usually passes anterior to the piriformis muscle to enter the greater sciatic notch. Detach the tendon of obturator internus and the two gemelli muscles as they insert into the femur (Fig. 7-44). If the sciatic nerve is bifid and you wish to perform a surgical dislocation of the hip, then also divide the
tendon of the piriformis muscle to prevent a traction lesion of the nerve. Using the short external rotator muscles as a cushion, carefully insert a retractor into the greater sciatic notch. Do not apply great pressure on this retractor as this will create a sciatic nerve palsy. Insert a second retractor into the lesser sciatic notch to expose the posterior column in its whole extent.
The posterior capsule of the hip is revealed. This is often torn or detached in cases of trauma. If the posterior capsule is intact and a direct inspection of the joint is required, make a T-shaped capsulotomy. Ensure that you avoid damage to the limbus when incising the capsule.
The inner surface of the acetabulum can only be viewed by distracting the femoral head. This can either be achieved by skeletal traction or with the help of a Schanz screw placed in the femoral head.
Posterior lip fractures of the acetabulum can be adequately visualized and fixed at this stage. If you require more extensive exposure of the posterior column, as, for example, a posterosuperior wall fracture, a transverse fracture with an associated posterior wall fracture or a T-shaped fracture perform an osteotomy of the greater trochanter. If the piriformis tendon is still attached to the greater trochanter develop a plane between the piriformis muscle inferiorly and the gluteus medius superiorly. Continue this dissection to the greater sciatic notch. Deep to the gluteus medius identify the gluteus minimus muscle and develop a plane between this muscle and the piriformis. Take care not to injure branches of the superior gluteal nerves and vessels which run in this intermuscular interval. Mark the bone from the tip of the trochanter to the vastus tubercle using cutting diathermy and then divide the greater trochanter from posterior to anterior, removing a piece of bone 5 mm in size. Creating a step osteotomy (Fig. 7-45) gives the osteotomized bone stability when it is reattached to the femur.
Figure 7-44 Divide the short external rotator muscles 1 cm from their insertion into the femur.
This bone will have the gluteal muscles and possibly the piriformis muscle attached to it superiorly and the vastus lateralis attached to it inferiorly. Divide the fascia overlying the vastus lateralis muscle for about 5 cm distal to the vastus tubercle to increase the mobility of the muscle. Then progressively evert the trochanter with its attached muscles over the anterior surface of the femur using a sharp retractor (Fig. 7-46). The small remaining attachment of gluteus medius to the intertrochanteric ridge will now need to be released. If difficulty is encountered mobilizing the fragment, the insertion of piriformis may sometimes need to be partially released if this has not already been done.
If you require access to the anterior surface of the hip joint capsule, flex and externally rotate the hip. Mobilize the insertion of gluteus minimus from the retroacetabular surface along the superior capsule to its femoral insertion along the anterior aspect of the trochanter. If further
exposure of the anterior structure is required, perform a Z-shaped capsulotomy to inspect the inside of the joint (Figs. 7-47 and 7-48). Apply traction to the limb to partially sublux the joint and allow visualization of the ligamentum teres. Divide the ligament and flex the leg to 90 degrees. Adduct the leg and achieve dislocation by applying external rotation. With the femoral head dislocated, appropriate anterior and posterior retraction provides a 360-degree view of the joint and a compete view of the femoral head (Fig. 7-49).
The trochanteric fragment can be reattached easily with screws during closure. Note that trochanteric osteotomies are associated with heterotopic bone formation in acetabular surgery.
The sciatic nerve is often contused by the original trauma. Great care must be taken throughout the operation that the nerve is not forcibly retracted. The divided external rotators will protect the nerve from direct trauma, but the nerve may still be injured by indirect forces transmitted through the retractor. The nerve is in most danger if a fracture table with continuous traction is used. You must be certain that the knee is flexed to avoid stretching the nerve.
Figure 7-45 Create a step osteotomy of the greater trochanter.
If a surgical dislocation of the hip is planned, check that the nerve is not bifid. If it is or if it actually goes through the substance of the piriformis muscle, divide the tendon of the piriformis muscle before fully everting the osteotomized trochanter.
The inferior gluteal artery leaves the pelvis beneath the piriformis. This vessel may be damaged by the original fracture or the artery may be injured during the surgical dissection. If the artery is transected, it will retract into the pelvis and bleeding will be brisk. To control the bleeding, apply direct pressure, then turn the patient over into the supine position. If the artery has retracted into the pelvis, vascular control can only be achieved by tying off the external iliac artery via a retroperitoneal
approach.
The superior gluteal artery and nerve leaves the pelvis above the piriformis and enters the deep surface of the gluteus medius. This attachment tethers the muscle, limiting the amount of upward retraction of the muscle and prevents you from reaching the iliac crest. The nerve and artery are at risk if the plane between gluteus minimus and piriformis needs to be developed.
How to Enlarge the Approach
Visualization of the inside of the acetabulum is always difficult because of the presence of an intact femoral head. In addition to using longitudinal femoral traction, specialized femoral head retractors are available that allow the head to be partially dislocated, thereby facilitating clear visualization of the dome of the acetabulum. It is critically important to obtain good visualization of the inside of the joint because the screws used for internal fixation may penetrate the joint.
The skin incision can be extended distally down to the level of the knee. Either split the vastus lateralis or elevate it from the lateral intermuscular septum to allow exposure of the lateral surface of the entire shaft of the femur.
The exposure cannot be usefully extended proximally.
Figure 7-46 Progressively evert the trochanter with its attached muscles over the anterior surface of the femur.
Figure 7-47 If further exposure of the anterior structures is required perform a Z-shaped capsulotomy.
Figure 7-48 The femoral head is now revealed.
Figure 7-49 Flex the hip 90 degrees and fully adduct it. Then dislocate the joint by applying an external rotation force. The femoral head then drops posteriorly to reveal a 360-degree view of the acetabulum.
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