2.8 Planning and decision making: surgical approaches
1 Why should we plan?
Acetabular fractures represent some of the most complex and challenging fractures faced by orthopedic surgeons. They occur in patients who have had significant trauma and there may be other significant, life-threatening injuries. Challenges that acetabular fractures may pose include difficult articular reductions that may need to be performed indirectly, the reduction needs to be anatomical to preserve hip joint function, and complex stable fixation involving both screw and plate constructs to allow for early range of motion.
To achieve these goals the surgeon has to operate on patients at a safe time after injury, using advanced imaging, through the correct approach for the individual fracture, using preplanned reduction maneuvers, and create stable fixation with precise fitting plates and screws.
2 Timing
Timing of surgery is guided by the patient’s clinical condition and the fracture pattern. Patients with acetabular fractures often present with associated visceral injuries and skeletal injuries. Preoperative evaluation needs to begin with a thorough physical examination and appropriate trauma workup. Specific issues that may delay definitive operative management include significant skin defects, closed degloving (Morel-Lavallé lesion), bowel perforation, and bowel ileus. It is often prudent to wait for resolution of concurrent issues before undertaking definitive care.
If possible we prefer to operate on patients with acetabular fractures at 3 to 5 days after injury. This allows for complete resuscitation of the patient after injury, fracture hematoma organization, and advanced imaging of the fracture. Operative intervention may be considered sooner for isolated posterior wall fractures; it has been shown that there is no clinical difference in blood loss with early operative intervention for this specific fracture pattern [1].
There are certain circumstances when more rapid operative management is indicated. These include hemodynamic compromise, evolving sciatic nerve symptoms, and irreducible femoral head dislocation. In these scenarios, prompt transfer and operative management are indicated ( Fig 2.8-1 , Fig 2.8-2 ).
The combination of an acetabular fracture with an associated pelvic ring injury is an uncommon injury pattern occurring in 5% of pelvic ring disruptions [2]. These high-energy injuries have associated mortality rate of 13% [2]. Patients with both a pelvic ring and acetabular fracture need expeditious hemorrhage control, skeletal stability, and hemostatic resuscitation. The pelvic ring needs to be recreated and maintained with an external fixator. The definitive surgical approach needs to be considered when placing external fixation pins and ideally pins are placed remotely from potential incision sites.
Patients presenting with hemorrhagic shock requiring angiography, with combined pelvic ring and displaced acetabular fractures, pose an even more difficult problem. Hemorrhage control is the priority, routinely performed using angiographic embolization in the isolated pelvic ring injury. However, if embolization is performed there is a high risk of infection for subsequent acetabular surgery, with Mason et al [3] reporting a 58% deep-infection rate. In the deep-infection group there was a disproportionate number of patients who had their entire internal iliac artery embolized [3]. This finding highlights the need to limit embolization to the most distal vessel that will still control any life-threatening hemorrhage. It remains unclear on the optimal timing of definitive acetabular surgery in these patients; however, it is prudent to extend antibiotic administration postoperatively ( Fig 2.8-3 ).
Patients who have sustained concurrent head injuries pose individual challenges. These patients often have long intensive care unit stays, and multiple surgical procedures. Definitive acetabular surgery should not be excessively delayed in these patients, as patients with head injuries are more likely to make exuberant callous and make late reduction of the acetabular fracture more difficult.
Occasionally, the severity of the patient’s injuries precludes operative management of the acetabular fracture for weeks. Late reconstruction of acetabular fractures is significantly more difficult because of fracture callous, shortening, and medialization of the proximal femur. This may change a relatively standard operation into a much more challenging case. Late reconstructions may require an extensile approach, longer duration of operation, greater blood loss, greater risk to neurovascular structures, more difficulty in obtaining a reduction, and a much greater chance of significant heterotopic ossification (HO). The maximum safe time limit between injury and operation is controversial. Matta [4] found that fractures operatively treated more than 14 days after injury were more likely to have a nonanatomical reduction; however, Ochs et al [5] found no difference in quality of reduction for fractures treated before or 14 days after injury.
3 Imaging
A thorough understanding of the complex fracture pattern and pathoanatomy is vital before attempting operative fixation. Three radiological views are used to evaluate and classify an acetabular fracture—AP view, iliac oblique view of the acetabulum, and obturator oblique view of the acetabulum. With experienced trauma surgeons these initial views provide the ability to classify acetabular fractures with good interobserver reliability [6]. Plain films give an excellent assessment of joint congruence and allow for assessment of other pelvic injuries.
Standard imaging is supplemented with computed tomographic (CT) scans and 3-D reconstructions. Thin slice CT scanning gives significant additional information including—excellent assessment of the displacement and rotation of the fracture fragments and columns; loose intraarticular bodies; assessment of the congruency or secondary congruency of the joint; femoral head fractures, assessment of the acetabular lip and dome; and marginal impaction.
Although obtaining both plain films and a CT scan may seem redundant, intraoperative decision making and technique depends on a clear understanding of the former. Plain films are superior for evaluating hip joint congruency and can be compared with intraoperative and postoperative images ( Fig 2.8-4 ).
A 3-D CT can help provide a better understanding of the spatial relationship of the fracture pattern and is useful for preoperative planning and teaching. The 3-D reconstructions should not be used in isolation, as 3-D reconstruction techniques may minimize individual fracture lines; therefore final assessment of the injury must also include plain x-rays and multiplanar thin slide CT [7]. The importance of 3-D reconstruction has been highlighted with an improved interobserver classification reliability and improvement in resident understanding of acetabular fractures [8].
Routine preoperative magnetic resonance imaging (MRI) scanning of acetabular fractures is controversial, as there is little useful additional information in planning acetabular fixation. An MRI is able to detect subclinical injuries of the sciatic nerve and occult injuries of the femoral head; however, it has a lower sensitivity to detect intraarticular fragments compared to CT [9].
Magnetic resonance venography is used to exclude preoperative deep vein thrombosis (DVT). Massive pulmonary embolus from DVT represents for practical purposes the only cause of mortality for the patient with stable acetabular fracture. Deep vein thrombosis has been reported to occur in as many as 60% of patients with lower limb injuries, and delay in treatment while awaiting transfer between institutions for definitive care increases the risk of DVT [10–12]. Letournel et al [13] reported a 3% incidence of clinically evident DVT with four fatal and eight minor pulmonary emboli in a series of 569 patients, despite most receiving anticoagulant prophylaxis. In a prospective study, Geerts et al [10] showed a 60% incidence of DVT in patients with primary lower extremity orthopedic injuries and Kudsk et al [11] revealed a 60% incidence of silent DVT by venography in patients with multiple trauma immobilized 10 days or more. Montgomery et al [14] used magnetic resonance (MR) venography to evaluate 45 consecutive patients with displaced acetabular fractures, noting 24 asymptomatic thrombi in the thigh and pelvis of 15 patients (33%). Preoperatively we prefer subcutaneous heparin combined with an intermittent pneumatic compression device, and routine MR venography to rule out a DVT [12, 14–16]. If a significant thrombus is detected, a removable inferior vena cava filter is placed preoperatively and the patient is treated with heparin intravenously before surgery.
4 Planning/templating
Preoperative templating is essential for understanding the complexity of acetabular fractures. Traditional drawing of fracture lines on paper using standard templating x-rays is not ideal for 3-D anatomy of the pelvis, or of the complexity of acetabular fractures.
A better understanding of the fracture may be achieved by drawing fracture lines on a “saw bone” pelvic model. Fracture lines should be drawn on a saw bone model by the surgeon after assessing plain films but before assessment of the CT scan. Once all fracture lines are drawn, the surgeon then compares the saw bone model to the CT scan and the 3-D reconstruction on the CT scan. This exercise is designed to develop the surgeon’s understanding of the fracture pattern using only the radiology available in the operating room. Saw bone preparation assists the surgeon in the optimal operative approach, reduction techniques, placement of reduction forceps, and placement of provisional and definitive fixation. Definitive plate fixation can also be prebent using a saw bone model and then sterilized to use intraoperatively. Saw bone models can be taken to the operating room, and even used intraoperatively by placing them in a sterile plastic bag to allow for intraoperative assessment of the preoperative plan ( Fig 2.8-5 ).
Occasionally, incomplete fracture lines are identified preoperatively. Generally, these incomplete fractures need to be completed intraoperatively to allow for reduction of the fracture.
Newer computer-based imaging technologies allow for virtual pelvic fracture models to be created, giving a greater appreciation of the fracture and the ability to practice reduction techniques [17]. Individual screw trajectory can be assessed, and plate length can be templated [18–21]. Currently, these technologies are not universally available and their role in acetabular fracture care is yet to be fully defined.
5 Operating room preparation
Operating room preparation is essential for ensuring optimal patient outcomes. Foley urinary catheters are placed in all patients to monitor urine output intraoperatively. This is especially important in anterior approaches, as the Foley catheter decompresses the bladder thereby decreasing the rate of iatrogenic bladder injury. Urine samples should be inspected preoperatively and postoperatively with hematuria raising the possibility of bladder injury.
Intravenous antibiotics should be administered 1 hour before the initial incision. Routine prophylaxis is 2 g of cefazolin, with additional dosing every 4 hours. Vancomycin is used as a second-line agent in case of penicillin or cephalosporin allergy.
Image intensification (AP and Judet views) are taken before initial incision to ensure that these key images can be obtained intraoperatively.
Preoperative hemoglobin checks should be performed and there is potential for the patient to require preoperative-packed red cell transfusions. Blood loss should be anticipated before undertaking operative treatment of an acetabular fracture, as bleeding may be significant from metaphyseal bone, or anomalous arterial or venous communications. Patients should be cross-matched 4–6 units of typed blood. Cell saver technology is helpful in limiting the quantity of allogeneic-packed red cell transfusion, and limiting the cost of blood transfusion [22].
Combinations of regional and general anesthesia are used for these patients. An ideal anesthetic provides optimal intraoperative and postoperative analgesia, and stable relative hypotension. Relative hypotensive anesthesia minimizes intraoperative bleeding, and allows for a dry field. This reduces the need for transfusion and decreases the duration of surgery due to better visualization. Communication with the anesthesiologist is vital because of the potential for life-threatening hemorrhage and to allow for expeditious hemostatic resuscitation. Preoperatively the patient should have multiple large bore intravenous catheters to allow for rapid resuscitation if required.
Electromyography (EMG) monitoring has become standard practice at our center to monitor for potential sciatic nerve injury. If changes in the responses from the nerve monitoring are noted intraoperatively, then the sciatic nerve is reexamined and all retractor placements are checked again and potentially removed from the field.
We do not routinely use somatosensory evoked potentials, as we have not found them to be as reliable as EMG. This is because somatosensory evoked potentials are calculated by averaging, hence delayed response compared to instantaneous EMG data. Moreover, the major reason to monitor is to identify potential for damage to the motor function of the sciatic nerve and prevent foot drop. This is a much more significant complication than sensory neuropraxia.
6 Specific challenges to reducing individual fracture patterns
6.1 Posterior wall
Although often believed to be the simplest fracture pattern, posterior wall fractures can pose real technical challenges. Posterior wall fractures often have significant marginal articular impaction. Marginal impaction is often under-appreciated, requiring elevation of articular fragments. There may be significant bone defects once the articular surface has been elevated, requiring grafting of the defect. Stable fixation of the posterior wall is vital to ensure maintenance of reduction of the femoral head and allow early range of motion. Fractures with marginal impaction are challenging with a reported loss of reduction of 25%, and a reoperation rate of 18% [23]. Further, subchondral fractures to the superior dome have worse functional outcomes compared with subchondral fractures centrally or anteriorly [24].
Fixation may be sparse in the small posterior wall fragments and specific hardware including spring plates should be available before embarking on surgery. A comminuted posterior wall fracture is a real technical challenge, with often a poor outcome ( Fig 2.8-6 ).
6.2 Posterior column
Generally, the femoral head displaces with the posterior column fragment. Reduction of the posterior column fragment requires lateral traction on the femoral head using a Schanz traction pin placed in the proximal femur.
Marginal impaction may also occur in a posterior column fracture; however, it is less common than in a posterior wall fracture. X-rays should be carefully inspected for a Gull sign, representing a displaced column and/or impacted articular roof fragment. In contrast to a posterior wall fracture, the posterior capsule is normally intact in a posterior column fracture, requiring capsulotomy to be performed to assess and to reduce any marginal impaction.
6.3 Transverse
The femoral head may spontaneously reduce under the undisplaced roof or it may migrate medially with the ischiopubic fragment in a transverse fracture. A displaced femoral head can be reduced with lateral traction on the proximal femur using a Schanz pin. It is more difficult to address these injuries in a lateral position, as gravity provides a deforming force for the ischiopubic fragment, making reduction maneuvers more difficult. In a transverse fracture both columns are injured and the approach is based on multiple factors including which column has the greater displacement, which involves the most significant part of the joint, fracture comminution, soft tissue, and patient factors.
Transverse fractures may also rotate centered around the pubic symphysis. This rotation means that the posterior column is more displaced than the anterior column and the superior part of the ischiopubic fragment is rotated in toward the true pelvic compared to the ischial tuberosity.
Occasionally, transverse fractures may be incomplete. In this situation the fracture may be difficult to reduce and the surgeon needs to be prepared to complete the fracture to obtain reduction.
6.4 Anterior wall
Like posterior wall fractures, anterior wall fractures can have marginal impaction. Frequently the quadrilateral plate is also displaced medially. Despite being an elementary type fracture, anterior wall fractures have poor long-term survivorship and should not be underestimated [25].
6.5 Anterior column
There are large morphological differences in anterior column fractures and these fractures can be defined as very low, low, intermediate, and high anterior column fractures. In very low acetabular fractures the femoral head often spontaneously reduces, while in other anterior column fractures the femoral head follows the displaced anterior column piece. In anterior column fractures the hip joint is often not exposed and reduction is achieved by indirect means. Be careful to ensure that all fracture fragments are reduced anatomically to create an anatomical reduction of the hip joint. Articular impaction may occur in these injuries. This may be addressed indirectly through the fracture gap, controlled cortical window osteotomies, or directly through a more extensile approach.
6.6 Posterior wall posterior column
This injury may have features of both a posterior column fracture and posterior wall fracture with associated marginal impaction. Generally in these injuries there is little displacement of the posterior column, which is different from a pure posterior column injury where there is usually significant displacement of the posterior column.
6.7 Transverse posterior wall
This fracture pattern is commonly associated with a posterior or central dislocation of the femoral head. The direction of femoral head dislocation guides the treatment. When the dislocation is posterior then the posterior fracture component is more important; when the femoral head is dislocated centrally then the transverse component is the dominant component [13].
6.8 T-type
Some of the most challenging fractures to treat are T-type fractures. Both columns are often displaced and rotated in this fracture pattern. The decision about which column to address first is challenging for these fractures and depends on many factors, such as the obliquity and height of the fracture, the presence of a wall fracture, the presence of additional fracture lines, patient obesity, and the surrounding soft tissues. Reduction may be difficult and require the use of combined approaches to achieve an anatomical reduction. If a combined approach strategy is used be careful to ensure that hardware from the initial approach and fixation does not inhibit the subsequent reduction of the opposite column.
6.9 Anterior column posterior hemitransverse
Reconstruction of the anterior column with a posterior hemitransverse and both-column fractures begins with a reduction of the individual peripheral iliac crest fracture fragments to portions of the intact pelvis. Working from the periphery toward the articular surface, fragments are sequentially reduced and provisionally stabilized. This process requires patience and a 3-D understanding of the pelvic anatomy. The iliac crest portion of the fracture can be reduced with pointed reduction clamps, or specially designed pelvic reduction clamps then stabilized by any combination of lag screws or reconstruction plates 3.5.
It is often helpful to predrill a gliding hole before fracture reduction to assure optimal lag screw position in the thin cortical cap of the iliac crest. Screws also can be placed anteriorly into the sciatic buttress.
The anterior column is always more displaced than the posterior component of this fracture, and the femoral head generally follows the anterior component ( Fig 2.8-7 ).
6.10 Both-column
A both-column fracture by definition has no part of the acetabular articular surface still attached to the axial skeleton. The acetabular fragments are translated medially with the femoral head. This medial translation is easy to appreciate on plain x-rays. The anterior fragment is generally attached to the pubic symphysis, and this fragment externally rotates and flexes on the symphyseal hinge as it moves medially. The posterior acetabular fragment has no bony connection and it generally internally rotates less than the anterior fragment.
6.10.1 Which column to fix first?
The decision about which column to fix first in a fracture that involves the anterior column and posterior column depends on various factors. Further, this decision determines the patient positioning and also the operative approach.
It is preferable to first fix the column that can be addressed more easily and more directly. Once an anatomical reduction has been achieved and stable fixation placed, then the second column can be addressed.
Importantly, note where the fracture exits the column as very low fractures may be almost extraarticular and are not the dominant fracture in the acetabulum. Obviously, it is essential to obtain anatomical fixation of the more significant portion of the acetabulum fracture.
It is often preferable to address the side that controls the shear forces better, and address this with an antishear plate. Finally, it is less difficult to insert a long screw into the posterior column from the anterior column than vice versa.
6.11 Associated femoral head fracture
A femoral head fracture is most often seen with a posterior dislocation of the femoral head. The decision about which femoral head fracture to address depends on the size of the femoral head fracture, the location of the femoral head fracture (Pipkin grade), and the presence of loose intraarticular bodies.
The vascularity of the femoral head has been well described, as has the technique of surgical hip dislocation [26]. Because a femoral head fracture normally occurs in the presence of a posterior acetabular injury, the Kocher-Langenbeck approach can be used with the addition of a “trochanteric flip” as described by Siebenrock et al [27].
It is unusual to have an isolated anterior column or anterior wall injury with a femoral head fracture. These cases need to be addressed on an individual basis with potential for using a combined anterior and posterior approach ( Fig 2.8-8 ).
7 Approach planning
The choice of correct operative approach is especially important in acetabular surgery. The specific approach to the acetabular fracture is decided once the patient is stabilized, clinical assessment completed, and all the imaging assessed. Basically, there are four options: posterior approaches, anterior approaches, extensile approaches, and combined approaches ( Table 2.8-1 ).
7.1 Positioning
The patient positioning depends on the surgeon’s operative approach. Patients may be positioned supine, lateral, floppy lateral, or prone. For each position the patient should be placed and supported appropriately on a radiolucent table. All bony prominences need to be well padded to prevent postoperative neuropraxia. Image intensifier should be checked before draping to assess the adequacy of intraoperative images, and allow for minor corrections in positioning.
Supine position may be used for all anterior approaches, and anterior extensile, approaches. The supine approach allows for excellent access with the image intensifier. The supine patient allows easy access for the anesthetist to the airway and allows for optimal venous access. This approach is also optimal for the polytrauma patient who may need to have concurrent injuries addressed. The sciatic nerve is at risk in this approach despite not being directly in the operative field. The sciatic nerve is put under stretch in the supine position with the hip flexed and the knee extended. This is believed to be the major reason for sciatic nerve neuropraxia during an ilioinguinal approach [28].
Lateral and floppy lateral positioning may be used for anterior, posterior, extensile, or combined approaches. A lateral approach may be favored for a simple posterior wall fracture, as it is an approach common to hip arthroplasty surgeons. Fracture reduction while the patient is in the lateral position is more difficult when the femoral head has displaced medially, as the reduction maneuver is working against gravity.
Significantly, floppy lateral positioning for a combined approach using the ilioinguinal approach and Kocher-Langenbeck approach is not equivalent to a supine ilioinguinal approach and a prone Kocher-Langenbeck approach. Although a floppy lateral position limits the need for positioning changes, there is a compromise to the access and visualization of the fracture compared with formal anterior and posterior approaches.
Prone positioning is used for patients with fractures of the posterior column or fractures with a transverse component where most displacement is posterior. Prone positioning allows lateral traction on the femur to reduce a medial displaced femoral head, without having to work against gravity as in a patient who has been positioned laterally.
Fracture classification determines the approach and positioning. So why would a surgeon choose one anterior approach over another?
Related posts:
2.11.3 Use of bone substitutes
2.11.4 Intraoperative assessment of acetabular fractures
2.9.2 Image intensifier-assisted closed techniques of reduction and fixation
2.10.2 Surgical management of wall and column fractures (type A)
2.10.4 Surgical management of associated both-column fractures (type C)
2.7 Specific surgical approaches and technique
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