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Techniques and Outcome in Pelvic Fractures

Techniques for Reduction and Fixation of Pelvic Ring Disruptions Through the Posterior Approach

Moed, Berton; Karges, David

Editor(s): Tornetta, Paul

Author Information
Clinical Orthopaedics & Related Research: August 1996 - Volume 329 - Issue - p 102-114
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Abstract

Traumatic disruption of the pelvic ring results in injury of varying degree to the bony pelvis and its soft tissue envelope. Various nerve, vessel, and visceral structures may be damaged. Overall patient treatment is dependent on an accurate assessment of the structural stability of the pelvic ring.2,27,29 Although a number of classification systems have been developed to assist in this assessment, the method initially proposed by Pennal and Sutherland19 and later modified by Tile and coworkers20,27-29 has gained common usage. By way of the patient history, physical examination, and appropriate radiographic studies, the pelvic injury can be categorized as stable (Type A), rotationally unstable but vertically and posteriorly stable (Type B), or unstable in all planes (Type C).28,29

In the acute injury phase, hemodynamic instability and structural instability of the pelvic ring are often interrelated.2,10,27 Emergent provisional bony stabilization using either an external fixator or a pelvic clamp can be lifesaving.6,10,18,32 However, these methods are biomechanically limited and are not intended for the definitive structural stabilization of Type C injuries.6,10,27,29,32

The characteristic feature of the Type C pelvic ring injury is complete disruption of the posterior sacroiliac complex. It may occur as a displaced fracture of the sacrum or ilium, as a dislocation through the sacroiliac joint, or as a combination fracture dislocation injury. This is the lesion that renders the pelvis unstable in all planes. Various treatment modalities are available such as traction, external fixation, symphyseal plating, and combinations of these techniques. Although there have been some recent reports to the contrary,16,17 reduction of the posterior injury is a treatment goal that is still thought to improve functional outcome.12,15,27,29,31 After completion of the initial resuscitative phase of treatment, posterior internal fixation is required as definitive management if one is to obtain fracture reduction and restore pelvic ring stability sufficient to allow early patient mobilization. To accomplish these goals of treatment, 3 basic surgical techniques are currently in use: (1) open reduction and internal fixation through a posterior approach,15 (2) open reduction and internal fixation through an anterior approach,14 and (3) closed reduction and percutaneous iliosacral screw fixation.22 Type C injured patients treated with open reduction and internal fixation through the posterior approach serve as the basis for this report.

SURGICAL APPROACH

For the posterior surgical approach, the patient is placed in the prone position. Intraoperative radiographic evaluation is important to assess fracture reduction and to accurately delineate the position of any inserted fixation devices. A radiolucent operating room table that allows C arm fluoroscopic visualization for anteroposterior (AP), inlet, and outlet views of the pelvis (Fig 1) is helpful in all cases but becomes mandatory with the use of iliosacral screws. A vertical incision is made approximately 1 to 2 cm lateral to the prominence of the posterior superior iliac spine extending from the level of the iliac crest, distally, to the greater sciatic notch (Fig 2). The extent and direction of the deep dissection is dependent on the exact location of the posterior injury. The gluteus maximus is released from its origin (the iliac crest, the sacrotuberous ligament, and the tendon of origin it shares with the erector spinae muscle).9 Some of the muscle fibers of the erector spinae are continuous with the fibers of origin of the gluteus maximus.8 Therefore, actual transection of muscle tissue is required for this release. The gluteus maximus can then be reflected anterolaterally with the gluteus medius and minimus muscles to as far forward as the iliac tubercle (Fig 3), as required for fracture visualization. The dissection is carried into the greater sciatic notch region exposing the posterior inferior iliac spine, the inferior aspect of the sacroiliac joint, and the piriformis muscle. The piriformis muscle originates from the anterior aspect of the lateral mass of the sacrum9 and is in the depths of the wound (Fig 3). Release of a portion of the origin of the sacrotuberous ligament may be required for complete exposure of this area. Clearing of the greater sciatic notch region is extremely important for cases involving injury to the sacroiliac joint. After a disrupted sacroiliac joint has been reduced, only its posterior inferior aspect can be visualized. Greater notch dissection allows direct palpation of the anterior aspect of the joint to further assess the status of the dislocation and provides access for the insertion of reduction clamps (Figs 3, 4). Elevation of the erector spinae and multifidus muscles permits exposure of the posterior sacrum to the midline. The posterior aspect of the sacral foramina can be visualized (Fig 3).

GENERAL CONSIDERATIONS

As previously noted, the main indication for posterior internal fixation of the pelvis is a translationally unstable, Type C pelvic ring injury. Diagnostic criteria include multiplanar instability at physical examination and greater than 1 cm displacement through the posterior sacroiliac complex.6,20,22 Therefore, manipulative reduction of a displaced posterior sacroiliac complex injury is generally required.

The technique of open reduction and internal fixation using the posterior surgical approach has as its main advantage that it facilitates this reduction of the posterior injury. Through a common incision, there is the potential for direct access to the ilium, sacroiliac joint, and posterior sacrum. This permits control of both sides of the traumatic injury with ample space remaining for the application of reduction clamps. Within the first few days of injury, the pelvic ring disruption is usually quite mobile. As the time delay between injury and surgical intervention increases, however, reduction of the posterior injury becomes progressively more difficult.15 Therefore, with time, this ability to mobilize the posterior injury directly becomes even more critical.

Sacral fractures have been classified into 3 zones according to anatomic location.5 Zone I is lateral to the sacral foramina in the sacral ala. Zone II involves the region of the sacral foramina. Zone III fractures extend through the central sacral canal. In Zone II and Zone III injuries, fracture reduction can cause damage to neural elements, trapped by an inaccurate reduction of the sacral foramina or compressed by retained bone fragments. The posterior approach allows direct visualization of fracture lines that course through the sacrum. Visualization of the sacral foramen should preclude nerve entrapment during fracture reduction. Bone fragments lodged in the sacral foramina or sacral canal can be removed before fracture reduction.

At times, the need may arise to use a combination of fixation devices. As a further advantage, the posterior approach accommodates a wide range of implants. Iliosacral screws,15 sacral plates,21 iliac screws and plates,12 transiliac bars,4 transiliac plates,1 and combinations thereof can all be used. Any transiliac fixation requires at least a limited exposure of the contralateral posterior iliac crest.

The major disadvantage of the posterior approach is the risk of impaired wound healing and subsequent infection with a combined incidence reported as high as 25% in 1 series.12 Patients with Type C pelvic injuries might have sustained a severe injury to the posterior skin and subcutaneous tissues manifested by hematoma or seroma formation or open wounds. Damaged soft tissues with impaired blood supply are at risk and often cannot withstand the added insult of surgical trauma. One should delay surgery to await healing of the soft tissues or select an alternative operative approach. In those situations that required delay, preoperative traction is helpful to prevent further cephalad migration of the hemipelvis and may improve the position. Bleeding from injury to the superior gluteal artery is an uncommon but very real potential complication of the posterior approach. The artery is at risk as it exits the greater sciatic notch superior to the piriformis muscle (Fig 3). It may be injured during the dissection of the greater notch area or by excessive retraction of the glutei muscles (Fig 3). Blunt dissection of the notch and attentiveness during the placement of retractors should minimize the risk of arterial injury.

REDUCTION TECHNIQUES

The tactic for reduction of a displaced pelvic ring disruption depends on many factors including the location and configuration of the injury and the body habitus of the patient. This variability requires a number of reduction clamps of different shapes and sizes (Fig 5).

As previously noted, dislocations and fracture dislocations of the sacroiliac joint require dissection of the greater sciatic notch to assess reduction of the dislocation (Fig 3). This dissection also provides a portal for reduction clamp application (Fig 4 A-B). Placed across the sacroiliac joint at this location, a reduction forceps is in excellent position to reduce the dislocation-nearly perpendicular to the obliquity of the joint line. There is a slight propensity for the joint to gap at its most superior aspect. Great care must be taken when positioning this clamp. The anterior aspect of the sacrum lateral to the foramina is cleared of soft tissue by blunt, finger dissection through the greater sciatic notch. One jaw of the clamp comes to lie in proximity to the exiting nerve roots, lateral to the foramina at the S1/S2 level (Fig 4B). The specific reduction instrument that can access this area is dependent on the size of the patient, and some trial and error is required. One of the most useful instruments is the small, 170-mm long, serrated bone forceps (Synthes USA, Paoli, PA). As delivered from the manufacturer, this clamp often does not open widely enough to be inserted and placed across the sacroiliac joint. However, the stop on the locking speed nut can be easily removed with pliers, allowing wider opening of the jaws of the clamp. After application of the clamp, the speed nut can be reapplied to lock the jaws in place. A fairly standard and less demanding method for reduction of a sacroiliac joint dislocation involves the use of a pointed reduction clamp with 1 tine located in the ilium and the other in a sacral spinous process (Fig 6). This technique is frequently successful. However, the line of reduction force is such that there may be residual anterior gapping or posterior subluxation of the joint. A combination of techniques is often the best solution (Figs 7, 8A-D). Other reduction aids include Schanz screws inserted in the iliac crest as a manipulative tool (joy stick), and bone screws placed in the ilium and the lateral crest, ala and pedicles of the sacrum, serving as anchoring points for clamp application (Fig 9A-E). The antishock pelvic clamp (Synthes USA)6 is constructed like a carpenter's bar clamp. Although not originally intended for this use, this clamp can function as a helpful intraoperative reduction aid (Fig 10). The antishock pelvic clamp is an unwieldy and potentially dangerous intraoperative tool. Before considering this tactic, one must be experienced in its application.

During the surgical procedure, but before the reduction, the injury site is usually inspected and cleared of debris. A standard laminar spreader facilitates this process. This injury site debridement is always an important step, but becomes imperative for Zones II and III fractures of the sacrum. This point has previously been discussed but cannot be overemphasized. The reduction techniques for sacral fractures are similar to those used for sacroiliac joint dislocations. Some modification is required depending on the zone of injury, however. For Zone I fractures there may be sufficient remaining intact bone to allow the use of the lateral crest, alar, or pedicular screw as a medial reduction clamp anchoring point (Fig 9B). For other Zone I fractures and Zone II fractures, the pointed reduction clamp method (Fig 6) works well. Zone III fractures with an intact S1 or S2 spinous process can also be reduced using the pointed reduction clamp. Otherwise, a screw placed in the contralateral sacral ala, S1 pedicle or ilium can serve as the anchoring point. This contralateral point of fixation usually requires a second incision. The pelvic reduction clamp (c in Fig 5) will usually span the distance between fixation points. The universal large distractor (Synthes USA) attached to the pelvis using Schanz screws and the antishock pelvic clamp are other options. A Schanz screw used as a joy stick assists in the reduction.

Type C pelvic ring disruptions with fractures of the iliac wing usually present as fracture dislocations of the sacroiliac joint. The reduction technique used depends on the amount of posterior ilium remaining attached to the sacrum (residual intact sacroiliac joint). Reduction of the displaced portion of the sacroiliac joint must be assessed by palpation through the greater sciatic notch. If the amount of intact sacroiliac joint is small, the techniques previously described for sacroiliac joint reduction should be used. As the iliac wing component increases in size, it becomes possible to apply a standard bone reduction forceps directly across the iliac fracture site. Alternatively, a Farabeuf or pelvic reduction clamp (Synthes USA), (Fig 5) can be placed across this fracture site through bone screws. Extraarticular iliac wing fractures are better addressed through an anterior surgical approach.

FIXATION TECHNIQUES

After the posterior injury is reduced, the next step is providing an internal fixation construct stable enough to allow postoperative patient mobilization. For sacroiliac joint dislocations and displaced fractures of the sacrum, there are a number of treatment alternatives. Through the posterior approach, these alternatives include the use of iliosacral screws, transiliac bars, transiliac plates, and local sacral plates. Each method has its advocates. Clinical studies and biomechanical testing have not shown the clear superiority of 1 technique over another. However, a few generalizations can be made. For unilateral lesions, all the aforementioned methods seem to restore pelvic stability and allow patient mobilization, especially when combined with fixation of the associated anterior ring injury.1,7,21,24,25,26 None is strong enough to allow full weightbearing in the early postoperative period without the risk of fixation failure. Bilateral posterior sacroiliac complex injury requires that at least 1 side be fixed to the axial skeleton. Transiliac methods of fixation are bridging techniques and are best reserved for unilateral fractures through the sacrum.

Iliosacral screws seem to be the strongest fixation method.24 The best purchase is obtained by using a 6.5-mm or 7-mm cancellous screw with a long thread length placed into the S1 body rather than into the sacral ala.13 The technique for inserting iliosacral lag screws into the body of S1 has been well described.15 This method is applicable for sacroiliac joint dislocations and fracture dislocations as well as for fractures through the sacrum. A C arm fluoroscopy unit and a radiolucent operating room table are necessary (Fig 1). Anteroposterior and 40° oblique radiographs of the pelvis are required (Fig 1). Preoperative radiographs should be obtained to ensure that there is nothing to obscure these views. The starting point on the ilium for screw insertion is located along a line running from the iliac crest to the greater sciatic notch approximately 15 mm anterior to and paralleling the crista glutea (Fig 11).15 Two fixation screws are desirable, located on either side of the midpoint of this line (Fig 11) and oriented at a right angle to the surface of the ilium. These general guidelines assume an anatomic reduction in all planes, an accurate distance measurement along the external surface of the ilium, and minimal patient to patient anatomic variability. The optimal distance from the crista glutea for this starting point (a in Fig 11) has been described as 15 mm15 and 20 mm.11 Adequate space for the insertion of 2 screws is also a concern.23 Surgical risks include sacral nerve root injury and penetration of the dura or nearby vessels by a wayward screw or drill bit. Use of the lateral fluoroscopic view to locate the starting point followed by insertion of the screws in a manner similar to that described for the percutaneous technique11,23,27 allow one to deal more effectively with these concerns (Fig 12A-C). Iliosacral lag screws provide excellent compression across the injury site. This is certainly desirable for sacroiliac joint fractures and fracture dislocations. However, if compression is not desirable, such as with a comminuted Zone II or Zone III sacral fracture, a fully threaded screw can be used.

Transiliac bars and plates are less demanding, safer methods of fixation. Either of these techniques requires at least 2 incisions and bilateral elevation of the erector spinae and multifidus muscles.1,3,4 For iliosacral bar insertion, a gliding hole is drilled through the posterior superior iliac spine, superficial to the line of the posterior aspect of the sacrum. The trocar tipped threaded bar (3/16-inch diameter [Zimmer, Warsaw, IN] or 6.4 mm diameter [Synthes USA]) is inserted using a hand or power drill. It will cut its own path through a sacral spinous process, if need be, to engage and pass through the contralateral ilium. Washers and nuts are applied and the bar is cut to size. If compression of the fracture site is not desirable, the bar can be inserted without predrilling, as if one were simply inserting a threaded Steinmann traction pin. Intraoperative fluoroscopy is not required. Although this is a very simple method, there is still the potential for technical difficulty. A critical step in the method is palpation of the posterior sacrum in Zone III to ensure that the bar does not compromise the spinal canal. Problems include lack of available space for a second bar and the potential for spinal canal compromise. Transiliac bars seem to be the weakest posterior fixation device and, if possible, should be combined with plating of the associated anterior ring injury.7,24,26 This method is probably best reserved for the fixation of sacral fractures rather than sacroiliac joint dislocations or fracture dislocations.25,26 The transiliac plate (a 4.5-mm reconstruction plate inserted through the posterior superior iliac spine with screw fixation to the ilium), addresses the space and canal compromise concerns of iliosacral bar insertion and has equivalent biomechanics.1 This method is a modification of a simple spanning tension band plate. Direct plate fixation of sacral fractures (local osteosynthesis) is an interesting and promising concept.21 The strength of this construct, which relies on small fragment plates and screws, is 1 obvious concern; the potential for nerve injury is another. Unfortunately, clinical data are limited in support of all these methods of fixation.1,3,11,25

Fractures of the ilium (sacroiliac joint fracture dislocations in which there is a large iliac wing component) can be fixed using standard methods of internal fixation. Lag screws are placed between the 2 tables of the ilium, usually in combination with a neutralization plate. The need for supplemental fixation of the associated anterior ring injury is controversial. Considering the biomechanical data that are related but not specific to this injury pattern,24 the addition of anterior fixation seems reasonable.

METHODS AND MATERIALS

In 1992, a protocol was initiated to evaluate the efficacy and early complication rate of reduction and fixation through the posterior approach. Indications for the use of this technique were Type C pelvic ring disruptions having complete resolution of any significant posterior soft tissue injury. Patients with a sacroiliac joint dislocation or fracture dislocation and unable to tolerate the prone position or having poor posterior soft tissues were considered candidates for the anterior approach (3 patients, 1 bilateral case). Patients with a sacroiliac joint injury or a Zone I sacral fracture that could be closed reduced and those with occult instability as revealed by physical examination were selected for percutaneous screw fixation (6 patients). Using these criteria, 25 patients with 26 Type C injuries were treated by reduction and fixation through the posterior approach.

The mechanism of injury was a motor vehicle accident in 22 patients and a fall from a height in 3. Nineteen patients had multiple injuries. Six sustained neural injury at the level of the nerve root or lumbosacral plexus affecting function in the ipsilateral sciatic nerve distribution. There were 3 open fractures, none with posterior open wounds. The posterior bony injury was a dislocation or fracture dislocation of the sacroiliac joint in 17 cases (1 bilateral). The sacrum was fractured in 9 cases (Zone I, 1, Zone II, 6, Zone III, 2). The delay from injury to operative treatment averaged 7 days (range, 3-21 days). Supplemental anterior fixation (plating for injury through the pubic symphysis; plating or external fixation for fractured rami) was used in all cases. External fixators were removed 6 weeks postoperatively. Time to the followup examination averaged 14 months (range, 6-36 months).

RESULTS

Reduction of the posterior injury was graded according to the method of Tornetta and Matta30 (excellent: ≤ 4 mm of residual displacement; good: 4-10 mm; fair: 10-20 mm; poor: > 20 mm). In this series, an excellent reduction was obtained in 25 of 26 cases. For the remaining case, residual displacement measured 8 mm (classified as good). In most, the residual displacement consisted of widening of the sacroiliac joint (Fig 8) rather than offset. There was 1 fixation failure which occurred approximately 6 weeks postoperatively after the patient had been discharged from the hospital. This patient had been noncompliant regarding weightbearing instructions. Reoperation was required.

A small area of superficial skin breakdown in proximity to the posterior wound occurred in 1 patient. This was treated with local care and subsequently resolved. Otherwise, there were no wound problems. No infections or iatrogenic nerve injuries occurred.

At the time of the last followup examination, occasional discomfort was reported by nearly all patients. Four patients complained of residual pelvic pain for which they were taking nonsteroidal antiinflammatory medications on an as needed basis. In only 2 patients did the pain significantly limit activities. Of the 6 traumatic nerve injuries, only 1 recovered. Two patients who had causalgia type pain in the early postoperative period experienced resolution of these symptoms.

In the group of 15 patients observed for more than 1 year, only 1 continued to be disabled. Except for work status changes to avoid heavy labor or a limited capacity for athletic activity, 14 patients were restored to a fully active ambulatory status. The 5 patients with a residual nerve deficit were limited only by their need for an ankle foot orthosis. Four of the 5 returned to their original workplace, 3 in jobs that required moderate physical labor. Although the 1 disabled patient did have a residual nerve deficit, the continuing disability was directly related to an associated head injury.

DISCUSSION

Unstable Type C disruptions of the pelvic ring are high energy injuries associated with significant morbidity and mortality. Despite the multitude of confounding variables, restoring pelvic stability and bony anatomy continue to be important components of the overall management scheme.10,12,15,27,31 However, the best method for accomplishing these treatment objectives remains in question. The emphasis of this report has been anatomic reduction as a goal and the facility of the posterior approach in attaining this goal.

Reduction and fixation through the posterior approach has been maligned because of its potential for serious complications.11,12 Alternative methods have been recommended.12,14,27 Other authors have shown that the risks of this technique can be overcome and its benefits realized.15,30,31 The authors' recent clinical experience is presented as an evaluation of the efficacy of the posterior approach. As such, the indications are that with careful patient selection the complications can be minimized and excellent reductions can be obtained. This report was not intended to evaluate functional outcome-the followup was too short, patient numbers were too small; outcome measures were not used. However, there is 1 point worth noting. Despite neurologic injury, patients can function well. The preinjury level of activity may not be regained, but pain free ambulation is a desirable and attainable goal.

Currently, the controversy is still brewing concerning the treatment for pelvic ring injuries. The conventional wisdom of previous decades, “they all do well,”27 is in the process of being replaced by another, “they all do poorly.” Just as there is a spectrum of injury, there is most assuredly a spectrum of outcome.29 It is important to further define the appropriate means to determine “functional outcome”-those all important buzz words of the 1990s. Otherwise, there is the danger of merely exchanging 1 conventional wisdom for another with its own self fulfilling prophecy.

Fig 1
Fig 1:
. Patient position and fluoroscopic visualization of the posterior sacroiliac complex.
Fig 2
Fig 2:
. Vertical incision for the posterior approach to the pelvis.
Fig 3
Fig 3:
. Deep dissection for the posterior approach. Reflection of the gluteus maximus muscle is exaggerated to show the underlying structures. Palpation of the sacroiliac joint through the greater sciatic notch is illustrated. Post. inf. = posterior inferior; sup. = superior; Post. sup. = posterior superior.
Fig 4A-B
Fig 4A-B:
. (A) Posterior and (B) anterior views of the application of a serrated bone forceps (f in Figure 5) through the greater sciatic notch in a plastic bone model.
Fig 5A-F
Fig 5A-F:
. Example of various reduction clamps. From left to right: (A) oblique reduction forceps with pointed ball tips; (B) large reduction forceps with points; (C) pelvic reduction clamp; (D) extra large pelvic reduction forceps with points; (E) Farabeuf reduction forceps; and (F) large serrated bone forceps.
Fig 6
Fig 6:
. Application of the large reduction forceps with points (B in Fig 5).
Fig 7
Fig 7:
. Illustration of the combined use of the serrated bone forceps in the greater sciatic notch and the large reduction forceps with points spanning the sacroiliac joint from the S1 spinous process to the ilium.
Fig 8A-D
Fig 8A-D:
. A 32-year-old man involved in a motor vehicle accident sustained a Type C pelvic ring disruption. Preoperative radiographs demonstrated the injury through the sacroiliac joint on the right and the pubic rami on the left. (A) Anteroposterior (AP) view. (B) Fluoroscopic intraoperative AP view illustrating the application of reduction clamps as demonstrated on the bone model in Figure 7. Postoperative radiograph and CT scan demonstrate the reduction and fixation. There is slight residual widening of the sacroiliac joint. (C) AP view. (D) CT scan through S1.
Fig 9A-E
Fig 9A-E:
. Demonstration of the use of screws to anchor reduction clamps. (A) Bone model with bone screws inserted and Schanz screw as a joy stick for reduction. (B) Application of Farabeuf clamps. (C) Anteroposterior radiograph of a clinical case with disruption through the right sacroiliac joint and pubic symphysis. (D) Intraoperative AP fluoroscopic view of the reduction using an angled oblique reduction forceps with pointed ball tips (a in Figure 5) through the greater sciatic notch and a Farabeuf clamp attached to screws in the ilium and S1 pedicle. (E) Postoperative AP radiograph.
Fig 10
Fig 10:
. The antishock pelvic clamp.
Fig 11
Fig 11:
. A line paralleling the crista glutea (uppermost arrow tip) running from the iliac crest to the greater sciatic notch. The optimal distance (a) between this line and the crista glutea is approximately 15 mm. Insertion points for screws (x) are on either side of the midpoint of this line.
Fig 12A-C
Fig 12A-C:
. Intraoperative fluoroscopic views from the case presented in Figure 8. (A) The lateral view after reduction. The reduction clamps are noted. The starting point for the drill bit has been targeted posterior to the sacral promontory and inferior to the line of the sacral ala. Drill insertion as shown on the (B) AP, and (C) lateral views. Inlet and Outlet views are also required.

References

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Section Description

SECTION I

SYMPOSIUM

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