2.11.2 Intrapelvic approach in acetabular fractures

10.1055/b-0035-121661

2.11.2 Intrapelvic approach in acetabular fractures

Eero Hirvensalo, Jan Lindahl

1 Introduction

Most fractures of the acetabulum involve the central acetabular area, which is difficult to reach with conventional approaches. Central protrusion or dislocation of the femoral head through the quadrilateral surface is seen in many fracture patterns. Comminution of the acetabulum and the osteoporotic dome has become a special fracture type in the elderly. Impacted large articular fragments of the central dome are common and need to be reduced to achieve anatomical or at least acceptable joint surface on the weight-bearing area of acetabulum.

At the time of the injury the compressive force is orienting to the bottom of the acetabular bowl, especially in fracture types in which the quadrilateral surface is broken ( Fig 2.11.2-1 ). The direction of displacement is medial or anteromedial (anterior column involvement) in this fracture type and is actually seen in many fracture combinations. Reduction of the entire displaced acetabular complex in the lateral direction is vital in achieving good reduction in these fracture types.

**Fig 2.11.2-1a–b** Fracture of a bowl. A medially oriented force breaks the bottom of the object. The contact area and direction of the force determine the breakage pattern. a The morphology of the acetabular fracture similarly depends on the direction of the force and the position of the femoral head in the acetabulum. The ideal way to fix the fracture is to place the plates in positions of maximum resistance to the displacement forces. b In central acetabular fractures this place is medial (ie, the bottom of the bowl).

The intrapelvic approach primarily is introduced for reduction and internal fixation of different types of anterior pelvic ring injuries [1, 2]. In the late 1980s this approach was also recognized as useful in acetabular fractures, either alone or in combination with the iliac window and/or Kocher-Langenbeck approaches [3]. Direct intrapelvic access to the central quadrilateral and anterior column areas allows for manipulation of the injured acetabulum and reduction of these medially displaced fragments and the entire fracture combination. Reduction of the most central and especially the cranial intraarticular fragments is possible under direct view. Moreover, fixation can be achieved through this true medial window.

2 Indications

2.1 Intrapelvic approach

All fractures of the acetabulum involving the low anterior column or anterior wall, with or without the central quadrilateral area, are suitable for the intrapelvic approach alone. The most common types of acetabular fractures in the elderly are anterior column fractures and anterior column associated with posterior hemitransverse fractures with involvement of the quadrilateral and/or the supraacetabular dome areas. Through the intrapelvic approach, the low anterior and medial main fragments can be accessed. If the posterior hemitransverse fragment is in the correct position, no further exposures are needed.

In T-type fractures with no residual displacement in the posterior column, this approach can be used for reduction and fixation without posterior procedures.

2.2 Intrapelvic approach with the iliac window

The intrapelvic approach can be combined with a lateral approach along the iliac crest (standard iliac window) whenever the anterior column fracture involves the iliac wing [4, 5]. In such cases these two approaches are used simultaneously ( Fig 2.11.2-2 ).

**Fig 2.11.2-2** Low midline and iliac window incisions. The midline incision begins from the symphysis pubis (SP) and extends up. The incision for the iliac window follows the margins of the iliac crest.

2.3 Combined anterior and posterior approaches

Both-column and T-type fractures are best treated with combined anterior and posterior approaches. Anterior surgery (intrapelvic approach with or without an iliac window) is performed first with the patient in the supine position. After the anterior procedures are completed, the position of the patient is changed for a Kocher-Langenbeck approach. Anterior column fractures associated with a posterior hemitransverse fracture need an additional posterior approach whenever residual displacement of the posterior fragment is present after the intrapelvic surgery. A summary of treatment protocols for different fracture types is presented in Table 2.11.2-1 .

**Table 2.11.2-1** Selection of approaches for different fracture types.
Approach	Fracture type
Anterior Intrapelvic +/- iliac window*	Anterior wall Anterior column Anterior column with posterior hemitransverse T-type (posterior column, minimally displaced) Transverse (simple, minimally displaced in adolescents) Both-column (posterior column, minimally displaced)
Posterior Kocher-Langenbeck	Posterior wall Posterior column Posterior column and posterior wall Transverse Transverse and posterior wall
Combined Intrapelvic +/- iliac window* with Kocher-Langenbeck	Anterior column with posterior hemitransverse (posterior column, displaced) T-type Both-column (posterior column, displaced, or comminuted)
* Approach along the iliac crest.

3 Technique for the intrapelvic approach

The intrapelvic approach allows for exposure of the anterior column, anterior wall, quadrilateral surface, and the medial aspect of the posterior column ( Fig 2.11.2-3 , Fig 2.11.2-4 ). The approach is created through a low midline incision starting from the symphysis pubis extending up, with the patient in the supine position. A Pfannenstiel-type transversal skin incision does not allow enough space to operate on the lateral aspect of the inner pelvis. The space between the rectus abdominis muscles is opened and the prevesical extraperitoneal area is exposed. The peritoneum is not opened. The bladder (marked with a catheter balloon) is pushed gently down. Insertions of the rectus abdominis muscles are not detached from the pubis. Dorsal periosteal tissue of the muscle attachment can be cleaned to create proper space for a fixation plate. Anterior and lateral attachments of the rectus muscles are always left intact.

Subperiosteal dissection below the abdominal muscles is continued laterally on the superior ramus following the inner (cranial) and anterior aspects of the pelvic brim. By remaining close to the bone and by using subperiosteal stripping only, injuring essential structures can be avoided. Corona mortis vessels are ligated whenever they are present and prominent. Small vessels can be managed with electrocoagulation. The iliopectineal fascia and other periosteal attachments on the brim are detached, which allows for elevation of the iliopsoas muscle with the neurovascular structures. This maneuver provides a better view of the inner pelvis (ie, the superior ramus, the anterior and inner side of the anterior column, and the quadrilateral area). The posteromedial side of the external iliac vein (the most medial vessel) is usually visible and easily recognized. The vein, the external iliac artery, the femoral nerve, and the iliopsoas muscle are lifted together with a hook.

The underlying obturator nerve and vessels entering the obturator foramen are identified. The bladder and the peritoneum covering the visceral structures are pushed down posteriorly and cranially with a broad retractor. A blunt retractor is placed over the obturator neurovascular structures into the ischial notch to allow a moderate posteromedial shift of the obturator bundle. Finally, the bony surface of the quadrilateral bone can be cleaned of the obturator internus muscle origin to allow good visualization over the central quadrilateral area and the entire medial surface of the posterior column.