2.10.1 Techniques of reduction and fixation for acetabular fractures: open methods

10.1055/b-0035-121656

2.10.1 Techniques of reduction and fixation for acetabular fractures: open methods

Jeffrey W Mast

1 Introduction

Fracture reduction is always the challenging step of bone surgery. Knowledge of the mechanism of the fracture, the region of the bone fractured, as well as the muscles attached to the various fragments aid the surgeon in understanding residual displacements. As with long bones, fractures of the pelvis involving the acetabulum also have characteristic displacements depending on the fracture type. This chapter covers techniques of reduction that are of proven utility.

2 Posterior wall fractures

Posterior wall fractures are approached through a posterior approach. The Kocher-Langenbeck exposure is most commonly used. A Judet table is used and the patient is placed in the prone position in the methods taught by Letournel. Posterior wall fractures can be demanding technically. They are frequently not a single fragment, and the comminution may be intraarticular or extraarticular. Large wall fragments may be split or fissured longitudinally, making both reduction and fixation more difficult. Because of the close relationship of the sciatic nerve to the external rotators of the hip, the difficulty encountered in the reduction of the wall fracture is the lack of safe space to use standard clamps to secure the reduction while fixation is applied. In addition, the ascending branch of the medial femoral circumflex artery is in close relationship to the tendon of the obturator externus muscle on its way to the femoral head. It courses proximally, diving under the obturator internus tendon on its way to piercing the posterior capsule. Thus, the main blood supply to the head may be injured unless special attention is used in the dissection.

Consequently, special instruments are necessary to reduce the displaced wall fragments. The picador is a ball spike-tipped rod that can be used to push against the fractured wall, forcing the fragments into reduction and holding them there until a K-wire can be drilled across the fragment to fix it in the reduced position. Instruments that are helpful also are pointed reduction forceps of various shapes and angulations. In addition, clamps whose limbs may be attached to screw heads inserted into the fracture fragments are frequently valuable. The Farabeuf clamp and pelvic reduction forceps are commonly used examples of these devices ( Fig 2.10.1-1 ).

In the author‘s opinion, one of the most valuable reduction tools is the plate used as a clamp ( Fig 2.10.1-2 ). This technique is particularly useful because there is limited space to use a clamp. In general, a short 3-hole plate is used. It is attached to the intact bone through a screw placed through the second hole, the empty hole of the plate. Its projecting end is adjusted so that it overlaps the displaced fragment, tightening the screw, causing the plate to be lagged to the bone. The end plate overlapping the displaced fragment clamps the fragment at the same level as the intact bone. Sometimes a small instrument, called a dental pick, is needed to toggle the fragment as the pressure is applied by the end of the plate. This helps to facilitate the fit of the fragment as the reduction force is applied by the end of the plate.

Reduction of the fragments is influenced by the position of the hip when posterior wall fragments have labral and capsular attachments. Hip extension and external rotation usually are required to replace the fragments back in their beds. One has to remember that capsular attachments that we want to preserve are influenced by the same forces following reduction and fixation. Accordingly, if the fragments are not well fixed, flexion and internal rotation may redisplace these fragments by pulling them out from under their fixation. The reduction may be lost, and—just as important to the outcome—the bared fixation may now contact the femoral head cartilage, causing wear and eventual destruction of the articular surface.

Most fractures of the posterior wall are associated with posterior dislocations of the hip. Letournel [1] has pointed out that what happens to the capsule of the hip joint at the time of fracture of the posterior wall, associated with a posterior dislocation of the hip, has an effect on the displacements found at surgery. Impaction of the articular segment is unlikely when the capsule is ruptured in association with a dislocation and a posterior wall fracture ( Fig 2.10.1-3a ). However, when the capsule is still attached to the displaced wall fragment, there is a high possibility of finding marginal impaction inside the socket ( Fig 2.10.1-3b ). Marginal impaction complicates the reduction of the posterior wall fragment. Before reducing the wall, the impacted articular surface must be accurately disimpacted and the fragments reoriented in their anatomical position using the reduced femoral head as a template.

**Fig 2.10.1-1a–b** Special clamps and the ball spike pusher to help with reduction in the acetabulum. a Clamps include the large and small offset clamp, the single-pronged and double-pronged clamp to fit over the iliac crest, pointed reduction clamps, Farabeuf clamp in two sizes and pelvic reduction clamps. Note also the ball spike pusher, which is invaluable in reducing small fragments of the acetabular wall and for pushing on the iliac crest. b All these clamps and the ball spike pusher can be fitted with a spiked disc that fits over the ball to prevent the spike from sinking into osteoporotic bone.

**Fig 2.10.1-2a–b** The plate as a clamp: Note how the plate overlapping the near side of an oblique fracture acts as one jaw of the clamp and the one on the far side of the fracture acts as the other jaw. The screw in the plate acts as the threaded spindle to tighten the jaws.

Restoration of the joint surface can be difficult, depending on the degree of impaction. The technique involves taking a small osteotome several millimeters above the impacted fragment, and driving the blade of the osteotome into the compressed cancellous bone behind the fragment. It is necessary to undercut the impacted fragment along its entire length. Gently, the impacted fragment is bent into its proper orientation using a curved osteotome as a lever. The objective is to slowly bend the fragment into position without breaking it ( Fig 2.10.1-3c ). The bone graft then is impacted into the secondary void created by articular disimpaction ( Fig 2.10.1-3d ). In another instance, with posterior dislocation of the femoral head, the posterior wall fracture with its intact capsular attachments may result in the wall fragments becoming incarcerated in the socket. The posterior fragments are displaced posteriorly with the femoral head but become anterior in position relative to the head, which is fully displaced into the dislocation cavity because they are tethered by the capsule.

An intraarticular incarceration occurs with the reduction of the dislocation as the fragments are pushed into the socket by the force of reduction of the femoral head. The capsular attachments remain intact but now exist between the interior of the socket and the “reduced” femoral head. The capsular attachments to these fragments are what make their management difficult because extracting these fragments from the joint without redislocating the hip is difficult. With the patient prone on the Judet table, distraction forces can be applied through the leg that subluxates the ball in the socket. This allows removal of the incarcerated fragments, although they may be difficult to extract even with this advantage.

As a rule, small fragments may be fixed with spring plates after reduction ( Fig 2.10.1-3e–f ), and posterior wall fragments must be buttressed by a plate fixed to the proximal and distal aspects of the intact posterior pelvic bone ( Fig 2.10.1-3g ). This buttress plate must make solid contact with the wall fragment and protect it from redisplacement. The screws must be oriented so as to not enter the joint. This can be facilitated by a guide pin placed before reduction in the intact bone, which defines the medial extent and orientation of the joint. Another method sometimes used is to drill the hole in the wall fragment for lag screw fixation before reduction. The location of the drill hole can be verified as central in the fragment and its extraarticular orientation confirmed. In this way the extraarticular position of the screw can be assured by examining the fractured surface of the wall fragment. Actually, this is a situation in which there is an advantage to have the patient free in a lateral position because the head may be readily dislocated. The “trochanteric flip” (see Video 2.7-3) is the most favorable surgical approach ( Fig 2.10.1-4 ). In this case, the fragments and their capsular attachments may be extracted from the joint easily ( Fig 2.10.1-5 ).

2.1 Posterior column fractures

Posterior column fractures can include transitional forms between extensive posterior wall and pure posterior column. As Letournel has described [1], column fractures occur in the frontal plane and the characteristic posterior column fracture consists of a fracture that is high (at the level of or including the angle of the greater sciatic notch), and may be associated with an additional fracture of the posterior wall. The column fracture usually is posterior medially displaced and rotated about the vertical axis inwardly.

The surgical approach is posterior and the position of the patient is prone. The Judet table is beneficial; the Farabeuf clamps as well as pelvic reduction forceps (also called Jungbluth clamps) are valuable. They may be attached by screws such that one jaw is attached to the posterior column fragment and one jaw to the intact posterior pelvis. In addition, a Schanz screw with a T-handle is inserted into the column fragment (usually the ischium), and used as a lever to control the rotation. The pelvic reduction forceps can be used to distract or compress and/or to displace the column anteriorly or posteriorly. Control of the posterior column reduction is confirmed by inserting a finger into the greater sciatic notch and palpating the oblique fracture line as the Schanz pin is manipulated, varying the rotation of the fragment.

The surgical problem that presents is how to obtain preliminary fixation so that the reduction aides may be removed from the bone to allow definitive fixation. This is another situation in which a 3-hole reconstruction plate may be used as a clamp to provide temporary fixation. After approximating the fractured bone surfaces with the pelvic reduction clamps, the plate is attached to the unstable fragment with a single screw. The edge of the plate is oriented to overlap the stable part of the bone. By tightening the screw, the plate end presses down on the intact portion, preventing further displacement of the posterior column. The bulky reduction clamps may be removed. The plate controls the fragment, even though no definitive fixation has been applied. Fine tuning of the position of the fragment is still possible because of this. When reduction is anatomical, the definitive fixation may be achieved with a well-contoured plate that crosses the main fracture line of the posterior column, the screws of which fix the oblique fracture line across the quadrilateral plate by passing from posterior to anterior.

**Fig 2.10.1-3a–g** a A posterior wall fracture with capsular rupture is unlikely to have marginal wall impaction. b Typical impaction of the posterior articular surface seen in posterior wall fractures with an intact capsule attached to the wall fragment. c Marginal impaction. Small osteotomes, such as Lambotte′s, may be used to cut above the area of impaction as illustrated. Osteotomes are worked above the impaction, prying it down using the femoral head as a template. This creates a gap above the reduced impaction. d Bone graft may be obtained from the trochanter, which is windowed; the cancellous bone is harvested and used to fill the defect above the reduced impaction. e Temporary fixation is then carried out using a plate as a clamp. As the screw is tightened, the plate clamps down on wall fragment providing provisional stabilization of the wall fragment. f Use of spring plates to reduce posterior wall fragments. g The buttress plate is contoured and placed over the ”spring plates,” reinforcing the fixation of the posterior wall.

**Fig 2.10.1-4a–c** The trochanteric flip technique. a A Kocher-Langenbeck or Gibson skin incision is made. The patient is stabilized in the lateral position. b After incising the aponeurosis of the tensor fascia lata and retracting it posteriorly, the posterior aspect of the vastus lateralis and gluteus minimus is mobilized from posterior to anterior after incising the fascia. c A trochanteric osteotomy is made from posterior to anterior and the mobilized muscles, along with the trochanter, are displaced anteriorly by flexing, abducting, and externally rotating the leg. The anterior capsule is opened and the hip dislocated anteriorly by external rotation.

**Fig 2.10.1-5a−g** Case of posterior dislocation using trochanteric flip approach. a Posterior wall fracture that is very superior in location. Note the decrease in the shadow of the source. b This is a good indication for the trochanteric flip surgical approach. c Iliac oblique view of same case. d Computed tomographic scan showing very superior location of the wall fracture in roof of the joint. e Fixation with multiple small spring plates and lag screws. f Postoperative iliac oblique view. g Postoperative obturator oblique view.

The area of contact between the major main fragments may be decidedly decreased when posterior column fractures are associated with posterior wall fractures ( Fig 2.10.1-6 ). Notwithstanding, the posterior column must be first brought into reduction ( Fig 2.10.1-7 ). The reduction can be confirmed by inspecting the intraarticular surface within the joint through the defect in the wall; then the wall fragment is fit into the remaining defect and fixed with screws. The technique described previously becomes even more helpful in these circumstances, and may be augmented by the use of 2 mm K-wires for temporary fixation. The ball spike pusher is useful to manipulate the wall and hold it closely approximated until it can be fixed by screws and buttressed by a plate that also fixes the posterior column fracture.

2.2 Anterior wall fracture

An anterior wall fracture essentially is a segmental fracture of the anterior column that includes the anterior segment of the acetabulum. Externally, it comprised the anterior lip and varying amount of the quadrilateral plate. The anterior articular facet and a variable portion of the acetabular fossa are involved on the inner surface.

The surgical approach used is the anterior ilioinguinal, or sometimes the anterior Smith-Petersen approach. The difficulties presented with this fracture are twofold. First, although itself a rare fracture pattern, it is most common in the elderly, frequently as a result of relatively low-energy injury. The bone involved commonly is osteoporotic. Second, the fracture lines exit in the region below the femoral vessels and iliopsoas muscle. Further, the extension of the fracture frequently involves the quadrilateral plate, which descends into the true pelvis from the pelvic brim. These circumstances lead to difficulty in exposure and visualization of the fracture lines and its bony landmarks. Reduction of the fracture becomes difficult under these circumstances. The femoral head is dislocated anteriormedially. Frequently, there is a medial impaction of the medial portion of the roof of the acetabulum.

**Fig 2.10.1-6** Posterior column-associated posterior wall fracture associated with a dislocation of the femoral head.

**Fig 2.10.1-7a–h** Posterior column, posterior wall technique of reduction and fixation. a Transitional fracture extended posterior wall. Posterior wall-associated posterior column with femoral head dislocation. b Preliminary reduction of the difficult inferior fracture with pointed reduction clamps and fixation of the fracture is achieved with a screw. c Reduction of the upper end of the fracture may be facilitated by a small 3-hole plate that pushes the fracture into reduction. It is then attached by a screw to the reduced fragment. d The picador is used to hold the wall fragment into position as a spring plate provides preliminary fixation. e Final fixation including buttress plate along the posterior column overlying the two spring plates. f Fixation of the posterior column posterior wall fracture similar to the illustration, including a posterior buttress plate and two small spring plates. g Iliac oblique. h Obturator oblique.

The Judet table may be advantageous in fractures in which there is marginal impaction. The head can be centered under the roof using a combination of longitudinal traction and lateral traction applied through the trochanter.

This may be verified by the use of the image intensifier. The displacement in wall fracture can be exaggerated and the marginal impaction can be treated through the displaced wall fragment using the reduced femoral head as a template for the reduction of the impacted articular fragments. The disimpacted fragments are supported by cancellous bone graft, which may be combined with demineralized bone matrix to give it a puttylike consistency to facilitate its application to the defects.

The wall fracture must be reduced following successful reduction of the impaction, with the femoral head centered below the roof of the remaining articular segment of the intact anterior column. Of course, there are clamps available for this purpose. The angled fibular clamps and the pointed reduction forceps are well adapted for use along the pelvic brim. Rectangular pointed reduction forceps may be used between the quadrilateral plate and the unbroken pelvis. One point is placed on the quadrilateral plate surface, while the other is placed on the external surface of the bone just lateral to the anterior inferior iliac spine—this way the wall fragment can be reduced.

However, the plate that must be used to buttress the fragment cannot be applied while the clamps holding the reduction are in location because they interfere with the optimal plate position on the pelvic brim. Consequently, it is more effective to precontour a pelvic reconstruction plate and slide it under the vessels and iliopsoas centered along the pelvic brim. Next, it is screwed to the body of the pubis distal to the exit of the distal fracture line, and affixed with screws along the pelvic brim on the proximal side of the fracture. Tightening the screws exerts a clamping effect on the wall fracture. Because there are no screws as yet fixing the wall fragment, minor changes in the reduction can be carried out with a ball spike pusher, or the mentioned clamps. When reduction of the wall is satisfactory, definitive screws may be applied through the plate, completing the stabilization. When the quadrilateral plate is a separate fragment or is comminuted, longer screws may be needed to fix or buttress this thin bone plate. Sometimes the screws must pass medial in the acetabular fossa. Occasionally, a thin plate (eg, a one-third tubular plate) is prepared by flattening it between two hammers and then bending it acutely so that one limb projects beneath the pelvic brim plate and one limb projects against the quadrilateral plate to buttress it.

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