AAOS Comprehensive Orthopaedic Review

Section 6 - Trauma

Chapter 53. Pelvic, Acetabular, and Sacral Fractures

I. Pelvic Fractures

A. Epidemiology


1. Most fractures occur in young adults involved in high-energy accidents such as motor vehicle accidents or falls from a height.


2. Pelvic fractures are often associated with other life-threatening injuries.


3. A smaller percentage of fractures occur in older patients with osteoporosis who sustain lower energy injuries, most commonly from a fall from a standing height. Patients with osteoporosis are also prone to insufficiency fractures of the pelvis.


B. Anatomy


1. The pelvis is formed by two innominate bones and the sacrum. Each innominate bone is formed from three ossification centers that fuse to become the ilium, ischium, and pubis (

Figure 1).


2. The anterior portion of the pelvic ring is joined by the ligaments of the symphysis pubis.


3. The posterior pelvic ligaments join the sacrum to the innominate bones and include the sacrospinous, sacrotuberous, anterior and posterior sacroiliac ligaments. These are some of the strongest ligaments in the body and take considerable force to disrupt. The iliolumbar ligaments connect the ilium to the L5 transverse process.


4. The sciatic nerve is formed from the lumbosacral plexus and includes the roots of L4, L5, S1, S2, and S3.


a. The L5 nerve root runs over the sacral ala approximately 2 cm medial to the sacroiliac joint.


b. The sciatic nerve exits the pelvis through the greater sciatic notch and typically runs deep to the piriformis muscle and then superficial to the remaining external rotators.


5. The common iliac artery divides into the external and internal iliac arteries.


a. The external iliac artery exits the pelvis under the inguinal ligament, becoming the femoral artery, and the internal iliac artery divides into an anterior and posterior artery.


b. The anterior division gives off several branches: the inferior gluteal artery exits the pelvis through the greater sciatic notch and supplies the gluteus maximus muscle, the internal pudendal artery exits the pelvis through the sciatic notch, the obturator artery runs anteriorly exiting the pelvis through the obturator foramen.


c. The posterior division of the internal iliac artery gives off three main branches: the superior gluteal artery runs across the SI joint and exits the pelvis through the greater sciatic notch, supplying the gluteus medius/minimus and tensor fascia lata muscles. The other two branches include the iliolumbar and lateral sacral arteries.


6. Other important vascular structures in the pelvis include the posterior venous plexus and the corona mortis.


a. The posterior venous plexus is a large collection of veins that join to drain into the internal iliac veins. Injury to the plexus accounts for most of the bleeding in many pelvic fractures.


b. The corona mortis is an anastomotic connection between the obturator and the external iliac systems. It can be either venous or arterial. The anastomosis runs across the superior pubic ramus, on average approximately 6 cm lateral to the pubic symphysis.


C. Surgical approaches


1. When performing an anterior approach to the sacroiliac (SI) joint, it is important to carefully dissect over the joint to avoid injury to the L5 root.


2. When performing a posterior Kocher-Langenbeck approach, the sciatic nerve should be identified and carefully retracted. The external rotators, with the exception of the piriformis, can be placed between the retractors and the nerve to provide some protection.


[Figure 1. Anatomy of the pelvis, showing bony structure and ligamentous connections.]

3. The obturator artery is at risk with the ilioinguinal approach to the acetabulum.


4. The superior gluteal artery is at risk with the posterior approach to the acetabulum or pelvis. If the artery is injured as it exits the notch, it can retract and angiography may be necessary to control bleeding.


5. It is important to look for and if necessary ligate the corona mortis during the ilioinguinal or modified Stoppa approach to the acetabulum.


D. Pelvic stability


1. Pelvic stability is determined primarily by the degree of injury to the posterior pelvis.


2. Stability has been described in both rotational and vertical planes.


a. An injury that disrupts only the symphysis pubis but not the posterior ligaments or sacrum should be stable to both rotation and vertical force.


b. An injury that disrupts the symphysis pubis and some of the posterior ligaments (sacrospinous, sacrotuberous, anterior sacroiliac) but not the posterior sacrospinous ligaments will be unstable to rotational force, but stable to vertical force.


c. An injury that also disrupts the anterior and posterior sacroiliac ligaments or results in a distracted fracture through the sacrum will be unstable in both planes.


E. Mechanism of injury


1. High-energy injuries can result in unstable fracture patterns.


2. Fractures resulting from a fall from a height are usually stable and often involve a minimally displaced superior and inferior ramus fracture in the front of the pelvis and an impacted sacral fracture in the back.


F. Clinical evaluation


1. Hemodynamic status


a. Hemorrhage is a leading cause of death in patients with pelvic fractures.


b. Patients with a pelvic fracture who present with hypotension have a marked increase in mortality compared with those who are hemodynamically stable.


c. There are three main sources for hemorrhage resulting from pelvic fractures: vascular, osseous, and visceral. Hemorrhage most often results from venous and osseous bleeding. Venous bleeding can lead to the formation of a large retroperitoneal hematoma. This bleeding may not be readily apparent on physical examination, but will be seen on CT scan of the pelvis.


d. Patients who present with tachycardia or hypotension should receive 2 L of crystalloid, according to ATLS guidelines. If hemodynamic stability is not restored, blood transfusion with type O-negative blood should be initiated immediately. Consideration should be given to angiography to evaluate possible arterial sources of bleeding.


e. Diagnostic peritoneal lavage performed in a patient with a pelvic fracture should be done supraumbilically because infraumbilical lavage can give a false-positive result because of tracking hematoma.


2. Neurologic injury


a. A detailed neurologic examination is required for all patients with a pelvic fracture.


b. The lumbosacral trunk and sciatic nerve are at risk with fractures and dislocations of the sacrum and sacroiliac joint. Careful assessment of the L5 nerve root (motor = extensor hallucis longus function, sensory = first web space on the dorsum of the foot) and the S1 nerve root (motor = gastrocnemius function, sensory = dorsum of foot minus first web space) should be performed. Motor strength should be graded from 0 to 5, as partial nerve palsy is common.


c. Although less commonly injured, the femoral nerve (L2, L3, L4; motor = quadriceps) and the obturator nerve (motor = hip adductors) function should be examined.


d. Pelvic fractures can also injure the pudendal nerve (S2, S3, S4), resulting in decreased perineal sensation and sexual dysfunction.


3. Gastrointestinal injury


a. Abdominal examination is performed to assess for tenderness or swelling.


b. All patients with a pelvic fracture also require a rectal examination. If a rectal injury is suspected, especially in patients with open pelvic fractures, rigid sigmoidoscopy is also required.


4. Genitourinary injury


a. Evaluation begins with inspection on physical examination. If blood is present at the urethral meatus, a retrograde urethrogram should be performed before attempting insertion of an indwelling urinary catheter.


b. The male urethra is less mobile and more prone to injury than the female urethra. The bulbous urethra is the part most commonly injured.


c. Other potential signs of urethral injury include a high-riding prostate on physical examination in males, and an elevated bladder on intravenous pyelogram.


d. Bladder injuries are common with pelvic fractures and should be looked for on CT scan or cystogram.


G. Radiographic evaluation


1. Radiographic evaluation begins with the AP view of the pelvis. Inlet and outlet views can be obtained to assess for AP and vertical displacement, respectively (

Figure 2).


2. CT is helpful to further define the fracture, especially in the sacrum and posterior pelvis, which may be obscured by bowel gas on plain radiographs (

Figure 3).


H. Fracture classification


1. The Tile classification scheme consists of three types based on the fracture stability (

Table 1).


a. Type A fractures are stable in both rotation and vertical directions.


b. Type B fractures are unstable to rotation but remain stable vertically.


c. Type C fractures are unstable in both rotation and vertical directions.


2. The Young-Burgess classification is based on the mechanism of injury and also consists of three main types (

Figure 4).



Anteroposterior compression (APC) fractures result from a force in the front or back of the pelvis. APC fractures are subdivided into three types and are sometimes referred to as the "open book" type injury.


Lateral compression (LC) fractures result from


[Figure 2. AP (A), inlet (B), and outlet (C) views of the pelvis.]

[Figure 3. Comparison of plain radiograph (A) with CT scan (B). The CT scan more clearly defines the posterior (sacral) fracture.]

[Table 1. Tile Classification of Pelvic Ring Lesions]


a laterally directed force to the pelvis and also have three subtypes.


Vertical shear (VS) fractures result from a vertically directed force through the pelvis such as in a fall from a height and are unstable injuries.


[Figure 4. Young-Burgess classification of pelvic fractures. The arrows indicate the direction of the force causing the injury. A through C represent lateral compression injuries; D through F depict the increasing injury to the ligaments of the pelvis with anteroposterior compression injuries; and G shows a vertical shear injury, which ruptures the pelvis anteriorly and posteriorly.]


A fourth type of fracture in the Young-Burgess classification involves a combination of any two patterns.


I. Treatment


1. Initial management


a. Initial treatment depends on fracture stability and the hemodynamic status of the patient. ATLS protocols should be followed for all patients with traumatic pelvic injuries.


b. Unstable fracture patterns in hypotensive patients require emergent stabilization in an effort to control ongoing hemorrhage.


c. Multiple devices have been used to stabilize pelvic fractures: bedsheets, pneumatic anti-shock garments (PASGs), pelvic binders, C-clamps, and external fixators. Bedsheets are readily available but require care to ensure that they are wrapped and held tightly around the pelvis. Towel clips are recommended to hold the sheet tightly rather than tying a knot. PASGs are effective in stabilizing fractures but are used less frequently because of potential complications such as compartment syndrome and respiratory compromise. The advent of pelvic binders has made quick and effective provisional stabilization of pelvic fractures relatively easy.


i. Rapid provisional fixation of unstable pelvic fractures can be performed in the trauma bay with application of the pelvic binder.


ii. Pelvic binders can remain in place during further diagnostic test such as angiography; if necessary, a portion of the binder can be cut to allow for vascular access.


d. Fluid resuscitation of hypotensive patients begins with placement of two large-bore IVs (16 gauge or higher) and infusion of 2 L of crystalloid. If the patient remains hypotensive or only transiently responds to fluids, then blood transfusion is indicated. Any coagulopathy should be corrected with appropriate transfusion of fresh frozen plasma and platelets.


e. If a patient remains hemodynamically unstable after fluid resuscitation and pelvic stabilization, emergent angiography should be considered. Although arterial bleeding is found in only 10% to 15% of patients, when it occurs emergent embolization can be lifesaving.


2. Definitive management—nonsurgical


a. Stable pelvic fractures (Tile type A or Young-Burgess APC1 or LC1) are treated nonsurgically.


b. Ambulation using crutches or a walker is allowed when other injuries allow.


c. Repeat radiographs should be obtained once the patient has been out of bed to verify that there have been no changes in pelvic alignment.


3. Definitive management—surgical


a. External fixation


i. Anterior pelvic external fixation can be used as definitive treatment of injuries that primarily involve the anterior pelvis but not for unstable posterior injuries. An example is the APC II injury, where external fixation can close down the anterior diastasis. Since the posterior SI ligaments are intact, they provide support to the posterior pelvis, similar to the binding on a book.


ii. The pins for the external fixator can be placed in the iliac wing, or alternatively, a single pin can be placed on each side in the supra-acetabular region (Hannover frame). With either construct, the bars connecting the pins should leave room for abdominal expansion. The Hannover construct requires use of a C-arm to ensure that the pins are above the acetabulum.


iii. An external fixator is more commonly used for temporary fixation. An anterior external fixator can provide stability to the front of the pelvis but cannot reduce the posterior pelvis when the SI joint is dislocated or there is a diastased fracture through the sacrum.


iv. The stabilization afforded by the external fixator can help limit hemorrhage in a hemodynamically unstable patient but requires conversion to definitive internal fixation when the patient's condition is more stable.


b. Open reduction and internal fixation


i. Anterior symphyseal injury can be treated with symphyseal plating. A Pfannenstiel incision is used, and reduction clamps are applied to the symphysis. A 3.5-mm reconstruction plate can be contoured to fit along the superior aspect of the symphysis.


ii. Multiple approaches can be used for open reduction and internal fixation of posterior pelvic injuries. Displaced SI joint injuries can be approached anteriorly, using a retroperitoneal approach. Following reduction of the SI joint, two short 3.5- or 4.5-mm plates can be used for fixation. The L5 nerve root runs approximately 2 cm medial to the SI joint and should be carefully retracted during fixation.


iii. Percutaneous iliosacral screws can be placed for SI joint dislocations or sacral fractures, provided closed reduction of any displacement other than pure diastasis can be achieved. Partially threaded screws can be used to close down diastasis of the SI joint, but care is required to avoid overcompressing sacral fractures that extend into the sacral foramen. SI screws can be placed with the patient either prone or supine. A radiolucent operating table and excellent fluoroscopic visualization are mandatory.


iv. Posterior plating of the pelvis requires the patient to be in the prone position. With transiliac posterior plating, vertical incisions are made over each SI joint. The SI joints are exposed and reduced with clamps. A reconstruction plate is contoured and placed subcutaneously and secured with screws into each iliac wing. Transiliac bars can be used in a similar fashion but tend to be more prominent and result in a higher risk of soft-tissue irritation and breakdown.


v. A more recent construct for posterior pelvic fixation is the triangular synthesis. This involves placing a pedicle screw at the L5 level and screws in the ilium and sacrum connected by bars. Biomechanical studies have shown this to be the most stable construct for posterior fixation.


J. Miscellaneous pelvic fractures and other conditions


1. Open pelvic fractures


a. Open pelvic fractures result from high-energy mechanisms and consequently have an increased risk for associated injuries and mortality.


b. Initial treatment follows ATLS guidelines, focusing on resuscitation and control of hemorrhage.


c. Rectal and pelvic examinations, including a speculum examination in women, should be performed to rule out hidden lacerations.


d. Tetanus booster and broad-spectrum antibiotics should be given.


e. A diverting colostomy is performed for open wounds in close proximity to the rectum to prevent contamination.


2. Fractures with neurologic injury


a. Neurologic injury occurs in approximately 10% to 15% of patients with pelvic fracture. The extent and permanence of neurologic injury is the most important predictor of long-term outcomes for these patients.


b. If a patient has a neurologic deficit and a CT scan shows entrapment of the nerve root(s) in the sacral foramen, posterior decompression should be considered.


c. Electromyography can be obtained at 6 weeks after the injury as a baseline from which to measure recovery.


d. Final outcome of a neurologic injury can take 18 months or longer.


3. Fractures with genitourinary injury


a. Treatment of an extraperitoneal bladder injury is broad-spectrum antibiotic treatment and urinary catheter drainage for 10 to 14 days. A cystogram is performed before catheter removal to ensure that the rupture has healed.


b. Peritoneal bladder ruptures require surgical repair. Any bony spicules penetrating the bladder should be removed.


4. Hypovolemic shock


a. Treatment begins with placement of two large-bore IVs and infusion of 2 L of crystalloid (normal saline solution). If the patient remains hypotensive or shows only a transient response to the fluids, transfusion should be started with type O-negative blood.


b. While fluid resuscitation is underway, any unstable pelvic fracture should be stabilized. Options include a sheet, a C-clamp, a PASG, an external fixator, or a pelvic binder.


c. Angiography should be considered as arterial pelvic bleeding can lead to rapid exsanguination.


K. Rehabilitation


1. Assuming stable fixation, patients are mobilized with touchdown weight bearing on the affected side. Range-of-motion exercises are begun as soon as symptoms allow.


2. After 4 to 6 weeks, weight bearing is advanced and strengthening exercises are started. Outpatient physical therapy may continue for an additional 6 weeks to 3 months to restore strength, balance, and proper gait pattern.


3. Final functional outcome can take 6 months to a year, sometimes longer if a neurologic injury is present.


L. Complications


1. Thromboembolic disease is a major concern for patients with pelvic fractures because of a high incidence of deep venous thrombosis (DVT) (35% to 50%) and pulmonary embolism (up to 10%). Fatal pulmonary embolism can occur in up to 2% of patients. Patients should be treated with chemical prophylaxis for DVT until ambulatory status is restored.


2. If other injuries preclude chemical prophylaxis, consideration should be given to placement of an IVC filter.


3. Iatrogenic nerve injury is a risk, especially with posterior fixation of pelvic fractures. If percutaneous iliosacral screws are used, a preoperative CT should be obtained to ensure a "safe zone" for screw placement.


4. With open treatment, self-retaining retractors should be used with caution because both neurologic and vascular injury have been reported.


5. Fracture nonunion in these patients is rare; malunion is more common, especially with vertically displaced fractures. Treatment of either is challenging, with long surgical times and large volume of blood loss common.



Figure 5. Anatomy of the acetabulum, showing the location of the anterior column (area with lines), posterior column (cross-hatched area), and ischiopubic rami (speckled area).]

6. Superficial wound infections often can be treated with appropriate antibiotics. Deep infection requires surgical irrigation and debridement.

II. Acetabular Fractures

A. Epidemiology


1. Acetabular fractures most often occur in young adults involved in high-energy motor vehicle collisions or falls from a height.


2. As with pelvic fractures, acetabular fractures also can occur in older patients with osteoporotic bone, usually from a low-energy fall.


B. Anatomy


1. The acetabulum or hip socket is part of the innominate bone and is formed from the ilium, ischium, and pubis.


2. The bony anatomy was described by Letournel as an inverted Y.


a. The anterior column begins superiorly with the anterior portion of the iliac wing and includes the anterior wall, the pelvic brim, and the superior pubic ramus.


b. The posterior column begins superiorly with the superior and inferior sciatic notch and includes the posterior wall, the ischial tuberosity, and most of the quadrilateral plate (Figure 5).


C. Surgical approaches—Type depends on location of the fracture.


1. The ilioinguinal approach is used to access the anterior wall and anterior column and the quadrilateral plate.


a. The incision begins approximately 2 cm above the symphysis pubis and extends laterally to the ASIS and continues along the iliac crest.


b. Three "windows" have been described with the ilioinguinal approach.


i. The first or medial window lies medial to the external iliac artery and vein.


ii. The second or middle window lies between the external iliac vessels and the iliopsoas muscle.


iii. The third or top window lies lateral to the iliopsoas.


c. Anatomic structures at risk include the femoral nerve, artery, and vein, which can be injured either during the approach or by retractors placed in the middle window.


d. In men, the spermatic cord is at risk in the first window. The bladder also lies deep in the medial window and should be carefully retracted.


e. The lateral femoral cutaneous nerve runs near the ASIS, and some authors recommend sacrificing the nerve because prolonged retraction can lead to a painful stretch injury.


f. The iliopectineal fascia runs between the femoral nerve and the external iliac artery. The fascia is incised during the approach.


g. The obturator artery and nerve lie deep in the medial window. The corona mortis is an anastomotic connection between the external iliac and obturator artery or vein. If encountered, the corona mortis should be ligated.


2. The Kocher-Langenbeck approach is used to access the posterior column or posterior wall of the acetabulum.


a. The incision begins approximately 5 cm anterior to the posterior superior iliac spine and carried distally in a curved fashion to the greater trochanter and then another 5 to 10 cm in line with the femoral shaft.


b. The fascia lata is incised, and the gluteus maximus muscle fibers are bluntly divided up to the level of the inferior gluteal nerve. The sciatic nerve lies posterior to the external rotators of the hip and should be identified.


c. The piriformis, superior and inferior gemellus, obturator externus, and obturator internus are incised approximately 1 cm from their insertion on the greater trochanter to preserve the ascending branch of the medial femoral circumflex artery, which runs deep to these tendons before joining the femoral arterial ring at the base of the femoral neck. The quadratus femoris muscle is left intact also to protect the medial femoral circumflex artery.


d. Minimal dissection of the joint capsule, which is often torn, is performed to preserve the remaining blood supply to the posterior wall fragments.


3. Other approaches include the extended iliofemoral, the triradiate, the Watson-Jones, the modified Stoppa, and the Hardinge.



Mechanism of injury



Like pelvic fractures, most acetabular fractures result from high-energy mechanisms, most commonly motor vehicle accidents or falls from a height.



Fracture pattern depends on the position of the femoral head in the acetabulum at the time of impact and the direction of the force applied.


Clinical evaluation



Patients with acetabular fractures often have multiple injuries and the initial approach to evaluation should follow ATLS guidelines.



Careful assessment of the ipsilateral lower extremity to rule out fracture or ligamentous injury of the knee should be performed.



The soft tissues overlying the greater trochanter should be carefully inspected for signs of a Morel-Lavallee lesion, a closed degloving injury resulting in a hematoma and liquefied fat forming between the subcutaneous tissues and the fascial layer.



Sciatic nerve function should be carefully assessed in the ipsilateral extremity, especially with fractures involving the posterior wall.


Radiographic evaluation



AP views of the pelvis, including Judet views (45° internal and external views) should be obtained.



Six radiographic lines should be assessed for any loss of continuity: the iliopectineal line (anterior column), the ilioischial line (posterior column), the anterior rim of the acetabulum (anterior wall), the posterior rim of the acetabulum (posterior wall), the dome (roof) of the acetabulum, and the teardrop (radiographic U) (

Figure 6).

a. The iliac oblique view better demonstrates the ilioischial line (posterior column) and the anterior rim (anterior wall).


b. The obturator oblique view better demonstrates the iliopectineal line (anterior column) and the posterior rim (posterior wall).


[Figure 6. Radiographic evaluation of the acetabulum showing the location of the six radiographic lines: (1) posterior wall, (2) anterior wall, (3) roof, (4) radiographic U, (5) ilioischial line, (6) iliopectineal line.]



CT scan better defines acetabular fractures, particularly in identifying the location and displacement of fractures and loose fragments in the hip joint. CT also helps with preoperative planning.



Involvement of the acetabular dome can be assessed by using roof arc measurements.

a. On the AP pelvis and Judet views, roof arc is measured by the angle formed by a straight line drawn though the center of the acetabulum and a line to the highest point of the fracture in the acetabulum. A roof arc angle less than 45° corresponds with a fracture in the weight-bearing dome of the acetabulum.



On a CT scan, the area within the 45° roof arc also corresponds with the superior 10 mm of the acetabulum (

Figure 7).


Fracture classification



The Letournel-Judet classification includes five simple and five complex or associated fracture patterns.

a. The simple patterns include posterior wall, posterior column, anterior wall, anterior column, and transverse.


b. The associated patterns include posterior column and posterior wall, transverse with posterior wall, T type, anterior column and posterior hemitransverse, and both column (

Figure 8).



Transverse, transverse with posterior wall, T type, anterior column and posterior hemitransverse, and both-column fractures involve both columns of the acetabulum. Both-column fractures differ from other types in that the articular surface is separated from the ilium. With the other four fracture types, a portion of the articular surface remains in continuity with the ilium.



For both-column fractures, the "spur" sign above the acetabulum on an obturator oblique radiograph is diagnostic.


[Figure 7. Roof arc measurement corresponding to the superior 1 cm on CT scan.]






a. Nondisplaced fractures or displaced fractures that do not involve the dome of the acetabulum are treated nonsurgically. The dome of the acetabulum has been defined as the area within the 45° roof arc or the superior 10 mm on a CT scan.


b. An exception to this rule is posterior wall fractures, which may not involve the dome but nevertheless can result in hip instability if a large fragment is involved.


c. Some both-column fractures have extensive comminution, but the fragments remain minimally displaced around the femoral head. This so-called secondary congruence also allows for nonsurgical management.


d. Other contraindications to open reduction and internal fixation include the following: associated medical conditions that prevent surgery; advanced osteoporosis or degenerative joint disease, making hip arthroplasty the better option; and local or systemic sepsis (

Table 2).


e. Mobilization out of bed with toe touch weight bearing for 10 to 12 weeks.


[Figure 8. Letournel-Judet classification of acetabular fractures showing the five simple and five complex fracture patterns.]

[Table 2. Indications for Nonsurgical Management of Acetabular Fractures]




a. Indications include fractures involving the dome of the acetabulum with at least 2 mm of displacement, fractures that result in instability of the hip joint, and fractures with trapped intra-articular fragments.


b. The approach selected depends on pattern and location of the fracture. Fractures involving a single column or wall can be approached through a single approach (ilioinguinal or modified Stoppa for anterior fractures and Kocher-Langenbeck for posterior fractures).


c. Both-column fractures may require both an anterior and a posterior approach or an extensile approach such as the extended iliofemoral (

Table 3).


d. Intraoperative traction of acetabular fractures can greatly assist fracture reduction.


e. Marginal impaction is often seen with posterior wall fractures and should be elevated and bone grafted.





Following stable fixation, patients should be mobilized as soon as possible. Weight bearing on the injured side is limited to touch down for 10 to 12 weeks.


[Table 3. Surgical Approaches Based on Acetabular Fracture Type]



With stable fractures or solid fixation, active and active-assist range of motion of the affected extremity is begun as soon as symptoms allow. Isometric quadriceps exercises and straight leg raises are begun early to minimize thigh atrophy.



Full weight bearing is delayed for 10 to 12 weeks, at which point progressive strengthening exercises are added. Aquatherapy can be helpful in transitioning to a fully ambulatory status.





As with pelvic fractures, DVT is a major concern for patients with acetabular fractures.

a. Prevention includes use of pneumatic compression boots and chemical prophylaxis.


b. Patients who cannot receive chemical prophylaxis should be considered for IVC filter placement.



Iatrogenic nerve or vessel injury can result from surgical treatment.

a. Maintaining the knee in flexion and the hip in extension during the Kocher-Langenbeck approach helps to decrease the tension on the sciatic nerve.


b. Self-retaining retractors should be used with caution.



Heterotopic ossification is most common with the extended iliofemoral and Kocher-Langenbeck approaches and least common with the ilioinguinal approach.

a. Patients at significant risk should be treated with either indomethacin (25 mg three times daily for 4 to 6 weeks) or radiation therapy (700 cGy) in a single dose. Radiation should be avoided in children or women of childbearing age.


b. For maximum effectiveness, prophylaxis should be given preoperatively or within 48 hours after surgery.



The risk of osteonecrosis is highest when hip dislocation occurs concurrently with acetabular fracture.

a. Dislocations should be reduced as soon as possible to limit thrombosis of stretched vessels supplying the femoral head.


b. With surgical treatment, the ascending branch of the medial femoral circumflex artery should be preserved.



Untreated Morel-Lavallee lesions have a high rate of infection.


III. Sacral Fractures

A. Epidemiology


1. Sacral fractures are considered a fracture of the pelvic ring. They occur principally in young adults as a result of a high-energy accident.


2. Older patients also can sustain these fractures, most often the result of a low-energy fall. Insufficiency fractures of the sacrum also can develop in patients with osteoporosis.


B. Anatomy


1. The sacrum is the terminal extension of the spine. The sacrum forms an articulation on either side with the ilium known as the SI joint. The joint is held together tightly by the anterior and posterior SI ligaments.


2. The sacral nerve roots (S1-S4) exit the sacrum anteriorly through the sacral foramen. The L5 nerve root runs on top of the sacral ala, approximately 2 cm medial to the SI joint.


3. Sacral root injury is most common with zone 3 injuries.


C. Surgical approaches


1. Sacral fractures and SI joint-dislocations can be exposed from either an anterior or a posterior approach. Alternatively, fractures that can be closed reduced may be amenable to percutaneous fixation. Percutaneous treatment is reserved for fractures in which any vertical or AP displacement can be reduced in a closed manner.


2. The anterior approach uses the top window of the ilioinguinal incision. The iliac muscle is elevated off of the ilium, and the SI joint is exposed. Medial dissection is limited by the L5 nerve root.


3. Posterior approaches use vertical incisions over the SI joint or a single midline incision. The gluteus maximus muscle is elevated to expose the SI joint and the posterior sacrum.


D. Mechanism of injury


1. Most sacral fractures result from motor vehicle accidents or falls from a height.


2. Repetitive stress in older patients can lead to insufficiency fractures.


E. Clinical evaluation is the same as for pelvic ring injuries, except that additional emphasis on the neurologic examination is necessary because sacral fractures often are associated with sacral root injury.


F. Radiographic evaluation


1. Plain radiographs include AP pelvis and inlet/outlet views.


2. Because sacral fractures are often difficult to fully visualize on plain radiographs, CT is often helpful to better define the fracture and the degree of displacement.


G. Fracture classification


1. The Denis classification divides the sacrum into three zones (

Figure 9).


a. Zone 1 includes the alar region lateral to the foramen.


b. Zone 2 includes the foraminal region.


c. Zone 3 is the central portion located between the foramen.


2. Fractures are defined based on which zone they involve.


H. Treatment


1. Nonsurgical—fractures that have minimal displacement or are impacted are typically stable and can be treated nonsurgically.


2. Surgical


a. Significantly displaced fractures benefit from surgical treatment. When reducing fractures, especially those involving zone 2, care should be taken to avoid overcompressing the fracture and the neural foramen because of the possibility of causing iatrogenic nerve dysfunction.


b. Loose bone fragments in the neural foramen may require removal to decompress the sacral nerve root(s).


c. Percutaneous fixation is unreliable in patients with osteoporotic bone.


I. Rehabilitation—essentially the same as described for pelvic fractures following a stable sacral fracture or one in which solid fixation is achieved.


J. Complications


1. Iatrogenic sacral nerve root injury can result from improper hardware placement with either open or percutaneous techniques.


2. Malreduction is a significant risk with vertically displaced fractures.


3. As with any pelvic fracture, DVT is a risk and requires prophylaxis.


[Figure 9. Denis classification of sacral fractures.]

Top Testing Facts

Pelvic Fractures

1. Pelvic fractures in young adults result from high-energy injuries and are often associated with other life-threatening injuries.


2. Rapid, provisional fixation of unstable pelvic fractures can be performed in the trauma bay with application of the pelvic binder.


3. Pelvic binders can remain in place during further diagnostic tests such as angiography; if necessary, a portion of the binder can be cut to allow for vascular access.


4. Open pelvic fractures may require a diverting colostomy.


5. External fixators can be used for definitive treatment of anterior pelvic injuries but not unstable posterior injuries.


6. Diagnostic peritoneal lavage performed in a patient with a pelvic fracture should be done supraumbilical, as an infraumbilical lavage can give a false-positive result due to tracking hematoma.


7. Patients with pelvic fractures have a high incidence of DVT (35% to 50%) and pulmonary embolism (up to 10%).


Acetabular Fractures

1. The area within the 45° roof arc angle corresponds with the superior 10 mm of the acetabulum on CT scan.


2. Secondary congruence of both-column fractures may allow successful nonsurgical management.


3. Intraoperative traction of acetabular fractures can greatly assist fracture reduction.


4. Marginal impaction is often seen with posterior wall fractures and should be elevated and bone grafted.


5. Untreated Morel-Lavallee lesions have a high rate of infection.


6. Heterotopic ossification is common, especially with the extended iliofemoral and Kocher-Langenbeck approaches.


Sacral Fractures

1. Sacral fractures are often difficult to fully visualize on plain radiographs; thus, CT is helpful in defining the fracture.


2. Percutaneous treatment is reserved for fractures in which any vertical or AP displacement can be reduced in a closed manner.


3. Sacral root injury is most common with zone 3 injuries.


4. Overcompression of fractures involving zone 2 should be avoided.


5. Percutaneous fixation is unreliable in patients with osteoporotic bone.


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