Pelvic Fractures Value of Plain Radiography

Jeremy W. R. Young, MD #{149}Andrew R. Burgess, MD#{149}Robert J. Brumback, MD #{149}Attila Poka, MD

Pelvic Fractures: Value of PlainRadiography In Early Assessment

and Management’

445

Musculoskeletal Radiology

Assessment of pelvic fractures in se-verely traumatized, clinically unsta-ble patients presents a diagnosticproblem. Traditional plain-radio-graphic classifications of the frac-ture are of limited preoperative val-ue to the surgeon who must applycorrective force in opposition to theoriginal force vector causing thefracture. Computed tomographicscanning is an effective method ofexamining the pelvis but is timeconsuming and may be impracticalin cases of severe injury. In a retro-spective analysis of the plain radio-graphs of 142 cases of pelvic frac-ture, four patterns of force wereidentified, presenting distinctive,recognizable radiographic appear-ances. These patterns are anteropos-tenor compression, lateral compres-sion, vertical shear, and a complexpattern. The resulting classificationof pelvic fracture, based on radio-graphic and clinical findings, corre-lates with associated injury to soft-tissue structures and enables thesurgeon to begin corrective proce-dures rapidly.

Index terms: Pelvis, fractures, 44.41 #{149}Pelvis,

radiography, 44.11

Radiology 1986; 160:445-451

1 From the Departments of Diagnostic Radi-

ology (J.W.R.Y.) and Orthopedic Surgery(A.R.B., R.J.B., A.P.) and the Maryland Instituteof Emergency Medical Services Systems, Uni-versity of Maryland Medical System, 22 South

Greene Street, Baltimore, MD 21201. From the1985 RSNA annual meeting. Received January10, 1986; revision requested March 17; acceptedApril 14. Address reprint requests to J.W.R.Y.

#{176}RSNA,1986

M ANAGEMENT of severe pelvicfractures and fracture disboca-

tions from massive trauma requires

treatment not only of skeletal trauma

but also of associated shock and com-

plications in order to lessen morbid-

ity and mortality. The classic treat-

ment of pelvic fractures has consisted

of pelvic slings, postural reduction,

skeletal traction, or internal fixation.

More recently, external fixation hasbecome increasingly used. A poten-tial management problem is misun-

derstanding of the exact type of frac-

tune that has occurred. This may be

the result of various confusing classi-

fications of pelvic fractures that give

little consideration to the mechanism

of injury and direction of the caus-

ative force but rely more on tradi-

tionab observations of individual

fracture patterns. Recently, Pennal et

al. (1) reported the importance of

classifying pelvic injuries according

to the direction of the force produc-

ing them. They found this of particu-

bar importance in progressive surgi-

cab management. Early stabilization

and realignment of the bony pelvis

often are effective in achieving he-

mostasis and reducing loss of blood

(2). However, to determine the cor-

nective forces that should be applied,

one must recognize the pattern of in-

jury and determine the direction of

the disruptive force. Incorrect assess-

ment may bead to incorrect and detni-

mental application of the stabilizing

devices, possibly causing further in-

jury to the associated soft tissue, par-

ticubarby to major blood vessels nearto the posterior pelvis.

Computed tomography (CT) may

permit detailed analysis of pelvic

trauma. However, we have found

that in a patient who initially is ex-

tremely unstable and requires rapid

surgical stabilization to assist in he-

mostasis, plain radiographs of the

pelvis can be obtained more quickly

than CT scans. CT scans are cleanly

superior to plain radiographs for ex-

act assessment of the pelvic ring, in-cluding determination of the locationof fracture fragments, but we believethat, in most cases, the correct diag-

nosis can be made by appreciating

the subtle radiographic findings in

each type of injury. This will also al-bow rapid recognition of the injurytype and instigation of appropriatecorrective surgical management.More definitive assessment by CTscanning may be needed at a later

stage of treatment.

Anatomy

An understanding of the anatomyof the pelvis is important for recogni-

tion of the patterns of fracture and

associated ligamentous injury. Thepelvis is basically a ring with three

components: the sacrum and two

pained lateral components, each com-

posed of ilium, ischium, and pubis.

These units have no inherent stabil-

ity and rely totally on ligamentous

support for their integrity. The sta-

bility of this ring depends over-

whebmingly on the stabilizing struc-

tunes of the sacroiliac joints (SIJs),

with the symphysis acting more as a

supporting “strut” (2).

The SIJs are divided into two parts:the lower, articular portion and the

upper tuberosities. The anticubar pom-

tion is covered by a thin layer of car-

tibage. Only very limited movement

is possible because of the strong sup-

porting ligaments.The short intemosseous sacroiliac

ligaments unite the tuberosities of

the ilium and sacrum (3). They are

the strongest ligaments in the body

and stabilize the posterior sacroiliac

complex (2).The posterior sacroiliac ligaments

(Fig. 1) make up two groups. The

first, shorter fibers anise from the

posterior superior and inferior spine

of the ilium and run obliquely to theridge of the sacrum. The second,

longer fibers run to the lateral por-

1. 2.

446 #{149}Radiology August 1986

Figures 1, 2. (1) Posterior view of pelvis. PS! posterior sacroiliac ligaments; ST sacrotuberous ligaments. (2) Anterior view of pelvis. ASI= anterior sacroiliac ligaments; 55 sacrospinous ligaments.

Figure 3. Diagram illustrating AP corn-pression. The direction of the injury force is

in the AP (on postenoantenion) direction

(large arrows). This has caused splaying of

the symphysis and rupture of the anterior

sacroiliac ligaments (R), sacrotuberous/sa-

croiliac complex (S), and symphysis liga-

ments (P), with “opening” of the pelvis.

tion of the inferior sacrurn, intermin-

gbing with the sacrotuberous liga-

ment (3). As their name suggests, the

anterior sacroiliac ligaments (Fig. 2)

pass from the anterior surface of the

sacrum to the adjacent ilium (3).

In addition to these fibers, the pos-

tenon portion of the pelvis is stabi-

lized by two groups of inferior con-

necting ligaments (3). The sacro-

tuberous ligaments (Fig. 1) are

extremely strong ligaments that ex-

tend from the lateral border of the sa-

crum (intermingling with fibers of

the posterior sacroiliac ligaments

from the posterior iliac spines) to the

ischial tuberosity. They run along-

side, and in places become contigu-

ous with, the sacmospinous ligaments.

The medial border forms a portion of

the pelvic outlet. The sacrospinous

ligaments (Fig. 2) also derive from

the lateral border of the sacrum,

where they intermingle with the sa-

crotuberous ligaments and pass di-

rectly to the ischiab spine.

Stability of the pelvis is also pro-

vided by the iliolumban and lateral

lurnbosacral ligaments, which run

between the fifth lumbar transverseprocess and the superior bonder of

the ilium and sacrum.

In the symphysis pubis, the oppos-ing bone is covered with hyabine car-

tibage and supported by fibrocarti-

lage and fibrous tissue. Infemionly,

the inferior pubic ligament adds sup-

port (3).

Pelvic Stability

Stability of the pelvis depends on

the integrity of the supporting biga-

ments. Tile (2) has demonstrated that

division of the symphysis ligaments

while the posterior ligaments are in-

tact allows the anterior pelvis to

“open” approximately 2.5 cm, with

the posterior structures preventing

further movement. Additional divi-

sion of the anterior sacroiliac, sacro-

spinous, and sacrotuberous ligaments

allows further opening until the

spines of the iliac bone abut the sa-crum. Additional division of the pos-

tenor ligaments gives rise to corn-

plete pelvic instability, as the iliac

wings can now be separated freely

from the sacrum.

Furthermore, Tile (2) has shownthat severe bleeding, usually from

the internal iliac artery or its

branches, is invariably associated

with injury to the posterior region,

with on without resulting instability.

This is not surprising, as most of

these injuries are the result of blunt

trauma, and massive forces are me-

quired to damage the pelvis or men-

den it unstable, particularly in young

patients. It is clear that accompany-ing injuries, both at adjacent and me-

mote sites, are to be expected, partic-

ulanly when there is posterior

involvement.

PATIENTS AND METHODS

A retrospective analysis was made ofthe radiographs of 142 patients with frac-

tunes of the pelvis. In each patient, three

views of the pelvis were obtained: an an-

teroposterior (AP) view with the patient

supine; a view of the pelvic inlet with the

patient supine, the x-ray tube angled 40#{176}

caudad, and the beam centered on theumbilicus; and a view of the pelvic outlet

with the x-ray tube angled 60#{176}cephalad

and the beam centered on the symphysis.

Each view was analyzed for the radiologic

appearances of the particular fracture

type. The fracture type was established

using historic, clinical, and radiographic

criteria.

RESULTS AND DISCUSSION

Patterns of Force

Four principal types of force were

identified as contributing to the inju-

4. 5.

Volume 160 Number 2 Radiology #{149}447

Figures 4, 5. (4) Type 2 A? compression fracture. There is diastasis of the right SIJ (large arrowhead), indicated by interruption of the

smooth line between the sacral arcuate lines and medial iliac bone. The symphysis is diastased 2.5 cm. This indicates rupture of the liga-

ments of the symphysis, the anterior sacroiliac ligaments, and, most likely, the sacrospinous and sacrotuberous ligaments on the right. In ad-

dition, there are vertical fractures of the inferior and superior pubic rami on the left (small arrows). (5) Type 1 AP compression fracture.

There is only a 1 .9-cm separation of the symphysis. No instability was found posteriorly. A vertical fracture of the left inferior pubic ramus is

seen, together with a largely undisplaced fracture of the posterior column of the left acetabulum (arrowheads). This fracture was stable dur-

ing manual examination.

nies studied: AP compression (exten-

nab rotation of the hemipelvis), later-

ab compression (internal rotation of

the hemipelvis), vertical shear, and a

complex pattern.

In our series, 22 (15%) of our cases

revealed AP compression, 81 (57%)

involved lateral compression, seven

(6%) involved vertical shear, and 32

(22%) involved complex fractures.

AP compression.-Injunies resulting

from AP compression, which corn-

pnised 15% of our cases, are the result

of direct AP force (Fig. 3). This force

vector frequently produces fractures

of the pubic ramus and may cause

ligamentous injury involving the big-

aments of the symphysis, the anterior

sacroiliac ligaments, the sacrospinous

and sacrotuberous ligaments, and the

posterior sacroiliac ligaments, either

singly or in combination (Fig. 3). AP-

compression injuries commonly pro-

duce the clinical “open book” or“sprung pelvis” type of injury, which

occurs with or without fractures of

the pubic mami. In our series, when

fractures of the pubic mami were

present, they were oriented vertical-

by in every case of AP compression.

This is an important feature differen-

tiating AP-compression from lateral-

compression injuries, where the frac-

tune line is in the horizontal or

coronal plane (Fig. 4). Opening of the

symphysis indicates that there has

been rupture of the ligaments of the

symphysis. However, as indicated

earlier, it has been shown that the

symphysis can be opened by as much

as 2.5 cm without rupture of the pos-

tenor ligaments of the pelvis. When

there is less than 2.5 cm separation,

the radiologist cannot determine

with plain madiogmaphs the integrity

of the posterior ligaments unless ob-

vious diastasis of the SIJ is seen. CT

scanning is more accurate is assessing

mild SIJ diastasis, but, in practice, we

have found that this imaging mode

may be oversensitive. Minimal ante-

nor separation of the SIJ seen at CT

study and not seen on plain radio-

graphs was not associated with poste-

nor instability in the three cases that

occurred in our series (Fig. 5). This

likely is due to persistent integrity of

the anterior sacroiliac ligament corn-

plex, with probable mild “stretch-

ing.” This concurs with Tile’s obser-

vations (2) that no division of the

sacroiliac ligament is necessary to

open the symphysis by 2.5 cm. Under

such conditions and with obvious ex-

temnab rotation of the pelvic wings,

mild diastasis of the SIJ must occur.

This is webb demonstrated in Figure

5, where separation of the symphysis

would be expected to cause mild wid-

ening of the anterior SIJs. However,

at clinical examination, this patient’s

pelvis was stable, indicating intact

ligaments. In practice, we examine

the pelvis manually to determine

whether the normal-appearing SIJsare stable when acute trauma has oc-

cunred.

Bucholz has designated threegroups of AP fractures on the basis of

the extent of posterior injury (4). We

have applied this concept to the ma-

diographic and clinical appearances

and have devised a three-stage cbassi-

fication of AP compression injuries.

Type 1 fractures are those in which

there is no posterior instability, ma-

diognaphic or clinical. Type 2 frac-

tunes are those showing separation of

the symphysis, with some posterior

instability involving the anterior sa-

croiliac complex. Type 3 injuries are

those with associated total disruption

of the sacroiliac joint. This cbassifica-

tion correlates well with the work of

both Bucholz and Tile and our own

observations (2, 4). In type 1 injuries,

an opening of the syrnphysis of less

than 2.5 cm is to be expected (Fig. 5).

In type 2 injuries, the symphysis maybe opened more than 2.5 cm, and theanterior sacroiliac joint will also ap-

pear to be opened (Fig. 4). In type 3injuries, there will be disruption of

the entire SIJ involving anterior and

posterior groups (Fig. 6).

Even when theme is no widening of

the symphysis, AP compression can

be diagnosed nadiographicabby by the

Figure 6. Type 3 AP compression fracture. There is total disrup-

tion of the posterior sacroiliac complex on the left (large arrow).

An undisplaced fracture of the posterior column of the right ace-

tabulum is seen (arrowhead). ac, sacrotuberous, and sacmospinous

7. 8. 9.


vertical appearance of pubic-rarni

fractures, if present. Of the 22 cases

of AP compression in our series, five

had less than 2.5-cm splaying of the

symphysis, with no demonstrable

posterior instability (type 1). Seven-

teen showed posterior instability.

Ten of these were type 2 injuries, and

in eight, openings of the symphysis

larger than 2.5 cm were demonstrat-

ed radiographically. In the other two

cases, separation of the symphysis

was less than 2.5 cm, but disruption

of the sacroiliac was evident on the

nadiographs (Fig. 4). Seven cases

demonstrated total disruption of the

sacroiliac and were therefore type 3

injuries.

Of interest is the finding of frac-tunes in the posterior pillar of the

acetabulum in 14 of the 22 cases of

AP compression, most likely the me-sult of anterior compression on a

flexed femur at the time of injury

(Fig. 6). This pattern was not seen in

lateral-compression injuries, where

acetabular fractures involve central

dislocation or involve the medial as-

pect of the acetabulum.

Lateral compression.-Injuries me-subting from lateral compression ac-

counted for 57% of our patients and

were associated with fractures of thepubic rami (100% in our series), sa-

cmum (88%), and iliac wing (19%).

Dislocations in the central hip may

also occur (19%). The fracture pattern

depends to a large extent on the posi-

tion along the lateral aspect of the

pelvis at which the force was applied

(Figs. 7-9). Ligamentous injury may

be minimal, as the forces are pmedOm-inantly compressive, although rup-

tune of the posterior sacroiliac liga-

ments may occur if the compressive

force is delivered anteriorly (Figs. 8,9). Compression fractures of the sa-

crum or sacroiliac joint may occur.

The fractures of the pubic nami are

characteristically horizontal or com-

onal in orientation (5) (Fig. 10).

Recently, because of the pattern ofinjury found, we have subdivided

lateral-compression injuries intothree types (5). In type 1, the force isdelivered over the posterior aspect ofthe pelvis, with little resulting pelvic

instability, although crush fractures

of the sacrum may be seen (Figs. 7,

10). In type 2, the force is more ante-nor, tending to cause internal dis-

placement of the anterior hemipelvis

and thus, potentially, external rota-

tion of the posterior hemipelvis, with

the anterior part of the sacroiliac

joint acting as a pivot (Fig. 8).

In type 3 lateral-compression frac-tures, there is such severe internal no-

tation of the ipsilatemal hemipelvis

that contralatemal external rotation

occurs, with subsequent disruption

of the contralatenal anterior sacroili-

Figures 7-9. Diagrams showing lateral-compression injuries. (7) A lateral force is applied posteriorly (arrow). This causes a crush effect on

the SIJ (A), which may be visible as a fracture radiographically. The characteristic fracture pattern of the pubic rami will be seen (B). No liga-

mentous injury is seen. (8) A force is applied anteriorly (arrow), causing the typical anterior fracture (B). In this case, however, rotation ofthe pelvis around the anterior sacral margin may occur, causing rupture of the posterior sacroiliac ligaments (R). A crush fracture of the sa-

crum (A) may also be seen. (9) A force is applied anteriorly (arrow at bottom right), causing internal rotation of the anterior hemipelvis. Con-

tinuing through to the contralateral hernipelvis (arrow at center left), the force causes external rotation. The result is a pattern of lateral com-

pression on the ipsilateral side, with apparent AP compression on the contralateral side and with rupture of the posterior sacroiliacligaments on the left (R) and rupture of the sacrospinous/sacrotuberous complex and anterior ligaments on the right (5). There may also be acrush fracture of the sacrum (A). Typical fractures of the pubic rami (B) are to be expected.


ligaments (5) (Fig. 9).

The importance of recognizing

these fracture patterns is in differen-

tiating them from fractures caused by

other force vectors. Fractures of the

pubic rami resulting from lateral

compression must be differentiated

from AP-compression injuries, so

that the appropriate corrective forcesare applied. If the significance of thehorizontal fractures of the nami is not

appreciated, or if the presence of a

crash fracture of the sacrum is not

recognized, incorrect compressive

forces can be applied, causing inter-

nab rotation of the hemipelvis and

compression of the pelvic wing (5).

Vertical shear. -Injuries caused by

vertical shear accounted for only 6%of our cases. These injuries are causedby a severe vertical disruptive force

delivered over one or both sides of

the pelvis lateral to the midline.

They generally occur in patients who

have fallen or jumped from a heighton have had a heavy load deliveredacross their head, shoulders or back,

such as those hit by a falling tree.

Both types of trauma effectively

cause the sacrum to be driven downbetween the pelvic wings. This typeof injury is associated with severe big-amentous disruption and pelvic in-

stability (Fig. 11). If the force is on

one side, the ipsilateral posterior andanterior sacroiliac, sacrospinous-sa-

crotuberous, and anterior symphysis

ligaments are usually involved. Frac-

tunes may also be seen involving the

pubic rami, sacrum, or iliac wing.These vertically orientated fracturesindicate the inferior-superior direc-tion of the force vector (Fig. 12). Ver-

tical displacement of the fracture

fragment can usually be appreciated

on the AP view but is best visualizedon the view of the pelvic outlet,which indicates the severity of thesuperior displacement.

Complex pattern. -Twenty-sevencases demonstrated a complex pat-

tern of injury in which at least two

different force vectors had been ap-plied. In 21 of these cases, the forcevector was predominantly of the bat-eral-compression type with AP corn-pression (1 9 cases) or vertical shear

(two cases) as the additional forcevector (Fig. 13).

In such cases, the surgeon must bemade aware of the complex nature ofthe injury because correcting forces

must reflect opposition to the onigi-

nab force vector. In cases of mixed an-

terior and lateral compression, thememust be an element of posteroanter-

ion stability applied by the stabilizing

device, as well as pure lateral meduc-tion. Simibarby, where an element of

vertical shear is seen, identified bythe view of the outlet, some inferior

corrective force is needed.

Straddle Fractures

Our experience suggests that the

so-called isolated straddle fracture of

all four pubic rami does not occur per

se and is seen with either anterior-compression (Fig. 14) or lateral-corn-pmession injuries (Fig. 10). Posteriorinjury has been shown to occur in ev-ery case of anterior pelvic fracture,confirming this point (6). In cases ofanterior compression, diastasis of theSIJ may be seen in addition to frac-tunes of the pubic nami. In fracturesdue to the lateral compression, corn-pmessive injury to the SIJ on sacrum isseen, and the fractures demonstratethe classic horizontal/coronal onien-tation.

Radiographic Study

Review of our cases reveals thatthe vast majority of diagnoses can bemade correctly by using radiogmaphsin the AP projection alone (94% inour series), although we always ob-tam a series of three views.

Inlet views of the pelvis are of usefor several reasons. They may dem-onstrate subtle compression or the

expansion of the pelvic ring seen inlateral- or AP-compression fractures.They may also demonstrate the con-onal nature of pubic-rami fracturesthat appear vertically oriented on theAP view, thus indicating the effectsof a lateral-compression force. In onecase, the inlet view enabled identifi-cation of a subtle “buckle” fracture of

the sacrum that was not identified onthe AP view.

The outlet view of the pelvis, al-though not diagnostic of any pelvic

Figure 10. Type 1 lateral compression fracture. In this injury,most of the lateral force was applied posteriorly, giving rise to a

lateral crush fracture of the sacrum on the right (small arrow-heads). The horizontal and overlap fractures of the pubic rami

(large arrowheads) are typical of this type of injury. There is no

displacement of the pelvic ring, and no ligamentous injury or in-

stability was expected or found.

Figure 11. Diagram of vertical shear injury.The ipsilatera! posterior and anterior sacroil-iac (R), sacrospinous/sacrotuberous (5), andanterior symphysis (P) ligaments are usuallyinvolved (compare Fig. 12). Fractures canalso be seen involving the pubic rami, sa-crum, or iliac wing (Q). These vertically on-entated fractures indicate the inferior-supe-rior direction of the force vector (largearrows).

Figure 14. Example of AP-compression fracture (so-called strad-die fracture). Vertical fractures of all four pubic rami are seen (ar-

rowheads). No significant posterior ligamentous injury has oc-

curred.

12. 13.


Figures 12, 13. (12) Vertical shear fracture. There are fractures through the left iliac wing (small open arrows) and both left pubic rami (ar-

rowheads). The fracture fragment in the left hemipelvis is displaced superiorly, indicating the predominantly superior direction of the force

of injury. In addition, there is disruption of the right SIJ, superior displacement of the right hemipelvis, and diastasis of the symphysis with

an avulsion of the inferior aspect of the right iliac wing (large open arrow). This is a “double” vertical-shear injury resulting when the pa-

tient jumped from a height. (13) Mixed fracture pattern. This fracture demonstrates features of both lateral compression and vertical shear.

The horizontal/coronal fracture of the superior left pubic ramus (dotted line) and media! displacement of the major hemipelvic fragment in-

dicate a lateral force as the cause of injury. However, the superior displacement of the major hemipelvic fragment argues for vertical shear.

The fracture through the left iliac wing (arrowheads) could occur in either type of injury.

fracture, provided an indication as to

the amount of vertical displacement

of the fracture fragment in cases of

vertical shear. This is of some impon-

tance to the surgeon in planning con-

rective treatment.

As a result of these observations, it

is now our standard practice to ob-

tam a single AP view of the pelvis in

every patient admitted to the Shock

Trauma Unit. If there is any sugges-

tion of pelvic fracture, either radio-

logic or clinical, inlet and outlet

views are then obtained.

The role of CT scanning in the

evaluation must be considered. There

is no doubt that CT scans can provide

information not gleaned from plain

nadiographs-including subtleties of

fragment displacement and the corn-

plexity of a particular fracture. It is

therefore the method of choice for

evaluating the acetabulurn for surgi-

cab reconstruction. In cases of pelvic

trauma involving the acetabulurn, we

always obtained CT scans.

CT scanning is also the most accu-rate method for visualizing the sacro-

iliac joint and sacrurn. We therefore

frequently use CT scans to define

posterior injury when definitive in-

tennal fixation is planned. However,

we do not use CT scanning routinely

as an admitting procedure in patients

with acute injuries to the pelvic ring

because we have found plain radio-

graphs to be highly accurate in the

overall assessment of the pelvic ring,

and because, in conjunction with

clinical examination, plain radiogra-phy allows inexpensive and rapid

evaluation of pelvic stability. Rapid

external surgical immobilization has

resulted from swift analysis of the

fracture pattern, and we have found

that, as a result, life-threatening

hemorrhage is now rare. In over 140

cases of pelvic trauma in this series,

angiography was required in only 19.

In eight of these, bleeding vessels


were found and embolized, and infive, surgical stabilization had notyet been performed. Of the other 11

patients, in whom no bleeding site

was found, external fixation had

been performed in seven.In our diagnostic workup, data ob-

tamed from plain nadiographs, thehistory of the accident, and clinical

examination are integrated to pro-

vide an overall assessment. Severeinstability with hemorrhage is treat-

ed initially with external fixation,unless angiography and emboliza-

tion procedures are believed to be

more urgent. Frequently, fixation of

the pelvis negates the need for angi-

ography. Signs of unobogic damage

are sought at the original examina-tion, and diagnostic urethrograms

and cystograrns are obtained, if mdi-cated. CT scanning is used in a sec-ondary role-either in more stable

patients, for whom urgent hemosta-

sis is not required and a detailed

view of the fractured pelvis is me-quired for definitive surgery, or

when fractures of the acetabulum arepresent, again as a preparation for

definitive surgical repair.

CONCLUSION

Plain radiographs are of consider-

abbe importance in cases of severetrauma to the pelvis. CT scanning is a

valuable diagnostic tool in the defini-tive evaluation of the fractures butcannot be done in many patients

who require immediate surgical im-mobilization. Also, in some centers,

CT scanning may not be readily

available. Appreciation of the types

of pelvic fracture, direction of theforces producing them, and likely

ligamentous injuries can be achieved

rapidly and inexpensively from plain

radiographs, indicating to the sum-

geon the type of disruptive force and

enabling the planning of the comrec-

tive procedure.Fractures of the pubic mami may of

themselves indicate the type of force

vector producing the fracture. How-ever, evaluation of the posterior pel-vic ring is vital. Horizontal fractures

of the pubic rami indicate that there

has been lateral compression and

should bead to careful inspection of

the sacrum for additional evidence of

sacrab compression and to a determi-

nation of the extent of posterior inju-

ry. Vertically oriented fractures of

the pubic rami indicate that there has

been AP compression and shouldlead to examination of the posteriorpillars of the acetabuli.

Diastasis of the sacroiliac may oc-

cur in any form of pelvic injury. Con-fimmation of the type of injury can beobtained by evaluation of the addi-tionab fracture patterns. U

References1. Penna! GF, Tile M, Waddell JP, Garside H.

Pelvic disruption: assessment and classifi-cation. Clin Orthop 1980; 151:12-21.

2. Tile M. Fractures of the pelvis and acetab-ulum. Baltimore: Williams & Wilkins, 1984.

3. Gray H. Anatomy of the human body.

Charles Mayo Gross, ed. 28th ed. Philadel-phia: Lea & Febiger, 1966; 318-320.

4. Bucholz RW. The pathological anatomy ofMa!gaigne fracture dislocations of the pel-vis. J Bone Joint Surg 1981; 63A:400-404.

5. Young JWR, Burgess AR, Brumback RJ. Lat-era! compression fractures of the pelvis: the

importance of plain radiographs in the di-agnosis and surgical management. Skeletal

Radio! 1986; 15:103-104.

6. Gertzbein SD, Chenoweth DR. Occult in-

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Documents

Pelvic Fractures Value of Plain Radiography