Anterior Approach to the Iliac Crest for Bone Graft

Anterior Approach to the Iliac Crest for Bone Graft

 

 

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

Landmarks

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.

Incision

The length of incision depends on the amount of bone graft that is required. For an extensive bone graft make an 8-cm incision parallel to the iliac crest and centered over the iliac tubercle (Fig. 7-2).

 

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.

 

 

Dang

 

 

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

superior iliac spine is taken as graft material, the inguinal ligament might retract causing an inguinal hernia.

 

How to Enlarge the Approach

Local Measures

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.

Extensile Measures

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.