PROCEDURE 45 Open Reduction and Internal Fixation of the Acetabulum

Hans J. Kreder, Richard Jenkinson, G. Yves Laflamme

PITFALLS

• Nonoperative treatment may be carefully considered under certain circumstances.

Fractures involving less than 20% of the posterior wall and with no joint incongruity on dynamic stress radiographs taken under anesthesia (Tornetta, 1999).

Fractures not involving the posterior wall and not an associated both-column fracture pattern, evaluated out of traction or, ideally, with stress radiographs taken under anesthesia (Olson and Matta, 1993; Tornetta, 1999).

Fractures not involving the weight-bearing articular surface as defined by roof arcs of greater than 45° on anteroposterior and both Judet views, or entering the joint greater than 1 cm below the dome condensation on computed tomography scans (Olson and Matta, 1993).

Note: Posterior column roof arc (measured on the iliac oblique view) may need to be greater to avoid joint subluxation during weight bearing (Fig. 1A–C). Joint subluxation may occur with weight bearing if the posterior column fracture enters the joint above the ischial spine (iliac oblique roof arc of 70°), or if the anterior column fracture enters the joint above the anterior inferior iliac spine (obturator roof arc of 30°) (Vrahas et al., 1999).

FIGURE 1

Posterior Approaches

Indications

Operative reduction is required for all acetabular fractures that demonstrate:

• Joint incongruity

• Femoral head subluxation

• Retained fragments between the articular surfaces (usually causing joint incongruity)

The posterior approach alone or as a component of a combined sequential or simultaneous approach may be considered in the following situations:

• Elementary and associated fracture patterns of the acetabulum involving the posterior wall

♦ Isolated posterior wall

♦ Transverse with posterior wall

♦ Posterior column with posterior wall

♦ T-shaped variant with posterior wall (additional or extensile approaches usually required)

• Elementary and associated fracture patterns involving the posterior column (without the posterior wall)

♦ Isolated posterior column

♦ Isolated transverse

♦ Posterior component of T-shaped variant (additional or extensile approaches usually required)

♦ Posterior component of anterior column with posterior hemitransverse or associated both-column fracture (primary approach usually anterior)

• Femoral head fracture fixation in association with an acetabular fracture

♦ Isolated femoral head fracture (usually approached anteriorly)

♦ Surgical dislocation usually required for femoral head fracture fixation (performed via posterior approach)

Controversies

• Operative versus nonoperative treatment for associated both-column fractures with secondary joint congruence (a fracture pattern in which the entire articular surface is free floating and no longer linked to the axial skeleton)

Most of these injuries should be treated operatively to allow early patient mobilization and to ensure optimal articular reduction.

“Secondary congruence” may be observed in associated both-column fracture patterns. Nonoperative treatment may be appropriate in this circumstance depending on patient factors such as advanced age and low demand. However, early mobilization may result in fracture displacement and a more difficult reconstruction at a later date.

• Timing of surgical treatment

Outcomes deteriorate when operative fixation is delayed. Fracture resorption and early callus are often seen beyond 3 weeks, making an anatomic outcome difficult to achieve and possibly necessitating extensile approaches for fracture reduction (Olson and Matta, 1993).

• Immediate total hip replacement

Poor-quality bone, marked fracture impaction of the weight-bearing region, advanced patient age, and comorbidity are all considered factors that mitigate against a good outcome following fracture fixation

Modern techniques of total hip replacement may be able to improve patient function and early mobilization in some of these patients. However, precise indications remain controversial.

• Percutaneous fixation

Closed reduction and percutaneous screw fixation of the columns (with or without computer-assisted navigation) may have a role in the management of low-demand elderly patients. The trade-off is a suboptimal reduction for a less invasive procedure.

Since anatomic reduction is an essential ingredient for a successful outcome, this management approach is of limited application and must only be applied on an individual basis for extenuating circumstances (that have yet to be defined).

Treatment Options

• Kocher-Langenbeck approach: may add trochanteric flip (digastrics) osteotomy to access high dome region (Siebenrock et al., 1998)

• Modified Gibson approach: facilitates approach to high dome region but access to distal column is more difficult (Moed and McMichael, 2008)

Examination/Imaging

Preoperative planning demands a thorough understanding of all components of the fracture pattern. The surgeon must plan:

• The surgical approach (anterior, posterior, added trochanteric flip, two approaches sequentially or simultaneously, an extensile approach)

• Optimal placement of lag screws for column fractures and wall fractures

• Method of buttressing walls (buttress plate, hook plate)

• Need for bone graft or bone substitute (to support elevated marginal impaction fragments)

Plain radiographs

• Anteroposterior (AP) pelvis and Judet (oblique) views allow delineation of all major fracture components and are generally sufficient to plan the operative approach.

• Figure 2 shows an AP pelvis radiograph with landmarks and fractures outlined.

• Figure 3 shows an obturator oblique radiograph (Fig. 3A) and related landmarks (Fig. 3B).

• Figure 4 shows an iliac oblique radiograph (Fig. 4A) and related landmarks (Fig. 4B).

Computed tomography (CT) scans

• Axial images are essential and usually sufficient for delineating:

♦ Femoral head fracture

♦ Marginal impaction (especially of the dome and posterior wall)

♦ Wall fragmentation

♦ Intra-articular fragments

• Coronal, sagittal, and three-dimensional reconstructions are usually not essential but may help to further understand complex fracture patterns.

♦ Axial (Fig. 5A) and sagittal (Fig. 5B) CT scans in one patient demonstrate marginal impaction and wall fragmentation.

♦ Selected CT scans of another patient illustrate intra-articular fragments (Fig. 6).

FIGURE 2

FIGURE 3

FIGURE 4

FIGURE 5

FIGURE 6

Surgical Anatomy

Bony landmarks (Fig. 7A)

• Greater trochanter

• Posterior iliac spine

• Greater sciatic notch

• Lesser sciatic notch

Muscles (Fig. 7B)

• Gluteus maximus

• Vastus lateralis

• Gluteus medius

• Gluteus minimus

• Piriformis

• Obturator internus

• Superior and inferior gemellus

• Quadratus femoris

Nerves (Fig. 8)

• Sciatic nerve

• Inferior gluteal nerve

• Superior gluteal nerve

Blood vessels

• Superior and inferior gluteal artery

• Medial femoral circumflex artery

The Letournel classification for acetabular fractures divides the most common fracture patterns into five simple types (Fig. 9A) and five associated types (Fig. 9B).

Figure 10 illustrates the two-column concept of the acetabulum (anterior column, white; posterior column, red).

FIGURE 7

FIGURE 8

FIGURE 9

FIGURE 10

PEARLS

• The fluoroscopy equipment should be set up on the side opposite the operative side.

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