x-rays: pelvis, hip & shoulder

X-rays:Pelvis, Hip & Shoulder

Feb. 22, 2006J. Huffman, PGY-1

Thanks to Dr. J. LordAlso thanks to Moritz, Adam and Steve Lan for some borrowed slides

and images

Goals:

As per instructions, this is a radiology talk ONLY. The focus is on reading as many films as possible.

Therefore, try your best to describe what you see as you would when on the phone with a consultant.

No epidemiologyNo managementNo associated injuries (i.e. vascular injury with

pelvic #)

Outline

1. Pelvisa) Anatomyb) Viewsc) Classification of

fracturesd) Practice

2. Hipa) Anatomyb) Views c) Fracturesd) Dislocationse) Practice

3. Shouldera) Anatomyb) Viewsc) Dislocationsd) Fracturese) Practice

Pelvis: Anatomy

Pelvis = sacrum, coccyx + 2 inominate bones

Inominate bones = ilium, ischium, pubis

Strength from ligamentous + muscular supports

Pelvis: Anatomy

Anterior Support: ~40% of strength Symphysis pubis

Fibrocartilaginous joint covered by ant & post symphyseal ligaments

Pubic rami Posterior Support:

~60% of strength Sacroiliac ligament

complex Pelvic floor

Sacrospinous ligamentSacrotuberous ligamentPelvic diaphragm

Pelvis: Anatomy

Very strong posterior ligaments Disruption of these is the cause of mechanical

instabilityArteries and veins lie adjacent to posterior arch

Pelvis: Anatomy

Divided into 3 columns: Anterior superior

column (= ilium)

Anterior inferior column (= pubis)

Posterior Column (= ischium)

Pelvis: Imaging

Plain films AP Inlet view / Outlet view Judet view (oblique – shows columns, acetabulum)

AP alone ~90% sensitive; combined w/ inlet/outlet views ~94%

Limited in ability to clearly delineate posterior injuriesPelvic films are NOT necessary in pts with normal physical

exam, GCS >13, no distracting injury and not intoxicatedAt least one study shows clinical exam reliable in EtOH

Gonzalez et al. J Am Coll Surg. 2002; 194: 121-5

CT scansEvaluates extent of posterior injury betterSuperior imaging of sacrum and acetabulumMore detailed info about associated injuries

Pelvis: Imaging - Acetabulum

a) Arcuate line

b) Ileoischial line

c) Radiographic U (teardrop)

d) Acetabular roof

e) Anterior lip of acetabulum

f) Posterior lip of acetabulum

Pelvis: Imaging - Acetabulum

Pelvis: Imaging – Normal Inlet

Pelvis: Imaging – Normal Outlet

Pelvis: Imaging

Radiographic clues to posterior arch fractures:

L5 transverse process avulsion* (iliolumbar ligament)

Avulsion of the lower, lateral sacral lip* (sacrotuberous ligament)

Ischial spine avulsion* (sacrospinous ligament)

Assymmetry of sacral foramina

Displacement at the site of a pubic ramus fracture

Pelvis: Fracture Classification Systems

2 most common are Tile and Young systems Tile Classification system:

AdvantagesComprehensivePredicts need for operative intervention

DisadvantagesDoes NOT predict morbidity or mortality

Young Classification System: Advantages

Based on mechanism of injury predicts ass’d injuryEstimates mortality

DisadvantagesExcludes more minor injuries

Tile Classification System

Type A: Stable: Posterior structures intact

Type B: Partially stable: Posterior

structures incompletely disrupted

Type C: Unstable: Posterior structures

completely disrupted

*Each type further classified into 3 sub-types based on fracture.

Tile Classification System

Type A: Stable pelvis: post structures intact A1: avulsion injury

A2: iliac wing or ant arch #

A3: Transverse sacrococcygeal #

Tile Classification System

Type B: Partially stable pelvis: incomplete posterior structure disruption B1: open-book injury

B2: lateral compression injury

B3: contralateral / bucket handle injuries

Tile Classification System

Type C: Unstable pelvis: complete disruption of posterior structures C1: unilateral

C2: bilateral w/ one side Type B, one side Type C

C3: bilateral Type C

Young Classification System

Lateral Compression

Anteroposterior Compression

Vertical Shear

Combination

*LC and APC further classified into 3 sub-types based on fracture

Young Classification System:

Lateral Compression (50%) transverse # of pubic

rami, ipsilateral or contralateral to posterior injuryLC I – sacral compression

on side of impactLC II – iliac wing # on

side of impactLC III – LC-I or LC-II on

side of impact w/ contralateral APC injury

Young Classification System:

AP Compression (25%) Symphyseal and/or

Longitudinal Rami FracturesAPC I – slight widening of

the pubic symphysis and/or anterior SI joint

APC II – disrupted anterior SI joint, sacrotuberous, and sacrospinous ligaments

APC III – complete SI joint disruption w/ lateral displacement and disruption of sacrotuberous and sacrospinous ligaments

Young Classification System:

Vertical Shear (5%) Symphyseal diastasis or

vertical displacement andteriorly and posteriorly

Combined Mechanism combination of injury

patterns

Young Classification System: Morbidity and Mortality

Tile A1

Tile B1 / Young APC II

Tile C1/ Young VS

Tile A1

No Fracture, just an IUD

Tile B3 / Young APC

Tile A2 / Young LC II

No #, just SC air from rib fractures

Pelvis: Acetabular Fractures

Four Categories:1. Posterior lip fracture

Commonly assoc. w/ posterior hip dislocation

2. Central or transverse fracture Fracture line crosses acetabulum horizontally

3. Anterior column fracture Disrupts arcuate line, ileoischial line intact, U

displaced medially

4. Posterior column fracture Ileoischial line disrupted and separated from the

U Judet (oblique views) or CT helpful if suspicious

Pelvis: Imaging - Acetabulum

Posterior Column #

Focus on the acetabular fractures.

Posterior Column #

Anterior Column #

Bilateral Anterior Column #

Posterior Lip #

Central (Transverse) fracture

Proximal Femur & Hip

Proximal Femur & Hip: Injuries

Fractures:Femoral neck, intertrochanteric, femoral

head, greater & lesser trochanter, subtrochanteric

Dislocations:Anterior, posterior, central, (inferior)

Proximal Femur: Anatomy

Ward’s Triangle

Proximal Femur: Images

AP Internal rotation!

Lateral Cross-table Lateral Frog-leg Lateral

Proximal Femur: Images

Cross-table lateral view* = ischial tuberosity

Proximal Femur: Fracture Classification

1. Relationship to capsule Intracapsular, extracapsular

2. Anatomic location Neck, trochanteric, intertrochanteric,

subtrochanteric, shaft

3. Degree of displacement

Proximal Femur: Approach to the film

1. Shenton’s Line

Femoral neck #

Dislocation

2. ‘S’ and ‘Reverse S’ patterns

3. Position of lesser trochanter

Dislocation

4. Femoral head size

Dislocation

5. Trace trabecular groups

Left posterior dislocation – note Shenton’s line

Proximal Femur: Approach to the film

Lowell’s ‘S’ patterns

Impacted femoral neck #

Hip: Dislocations

EtiologyAdults: high energy mechanism (MVA)Elderly, prosthetic joints, kids < 6yo: minor mech

Types:Posterior >> anterior > central (> inferior)

Orthopedic emergencies:Urgent reduction after ABC’s / stabilizationSignificant neurovascular complicationsOften multiple associated injuriesMandate CT post-reduction

Hip: Dislocation imaging

Plain Films: ant vs. post dislocationsFemoral head size

Posterior dislocation femoral head smallerLesser trochanter visibility

Post dislocation adduction & internal rotation, lesser trochanter not seen

Ant dislocation external rotation; lesser trochanter clearly visible

CT Indicated for more detailed evaluation of

femoral neck, intra-articular #’s, and acetabulm

Anterior dislocation

Posterior dislocation

Lesser trochanter

Proximal Femur: Fractures

Femoral head fracture:Usually 2° to dislocationPipkin classification

Femoral neck fracture:Can be subtle (check lines, ‘S’)Describe as nondisplaced (15-20%) vs displaced

Intertrochanteric fracture:High energy or weak boneClassify according to number of bone fragments

(e.g. two-part)

Displaced femoral neck fracture

Nondisplaced femoral neck #

Two-part intertrochanteric fracture

Three-part intertrochanteric #

Proximal Femur: Fractures

Isolated trochanter fracture:Rare (women more than men)Direct fall or avulsion by iliopsoasOutpt management

Subtrochanteric fracture:#’s b/w lesser trochanter & point 5 cm distalCommon site for pathologic fracturesVague symptoms

Occult fracture:~%5 of hip fractures not seen radiographically

Isolated greater trochanter #

Isolated lesser trochanter #

Subtrochanteric fracture

Proximal Femur & Hip

Practice

Intertrochanteric fracture 2° to mets from prostate CA

Pipkin III femoral head fracture and posterior dislocation

Shoulder

AC separationClavicle fractureScapula fractureShoulder dislocation

Shoulder: Anatomy

3 bones:ClavicleHumerusScapula

3 joints:AcromioclavicularGlenohumeralSternoclavicular

1 articulation:Scapulothoracic

Shoulder: Anatomy

Shoulder: Anatomy

Shoulder: Images

True APShould see no overlap of humerus over the

glenoid

Lateral (transcapular)Scapula looks like a ‘Y’)

AxillaryBest “true lateral” view of the shoulder

AC view100° abduction

Shoulder: Images

Internal rotation

External rotationMore useful for soft-tissue

evaluation

Normal True AP of the Shoulder

Normal lateral film of the shoulder

Normal axillary film of the shoulder

AC Separation: Classification

Type I Sprain of the AC joint CC distance maintained (N = 11-

13mm)

Type II AC ligaments disrupted Joint space widened CC distance maintained Clavicle rides upward (<50% its

width)

AC Separation: Classification

Type III (and IV, V, VI) Complete disruption of AC and

coracoclavicular ligaments as well as muscle attachements

Joint space widened CC space is increased

(5mm difference from uninjured side)

Clavicle is displaced

Type III AC separation – AC view (100° Abduction)

Clavicle Fracture

Classified anatomically:

1. Medial third (5%) – direct blow to the anterior chest

2. Middle third (80%) – direct force to lateral aspect of shoulder

3. Lateral third (15%) – direct blow to the top of shoulder

I. Lateral to the coracoclavicular lig. (stable)

II. Medial to the coracoclavicular lig. (tend to displace)

III. Involves the articular surface

Fracture of the middle third of the clavicle

Comminuted fracture of the middle third of the clavicle

Distal third clavicle fracture – type II

Scapula Fracture

Classified Anatomically:I. Acromion process, scapular spine or coracoid

process

II. Scapular neck involved

III. Intra-articular fractures of the glenoid fossa

IV. Scapular body involved (most common)

Type I scapular fracture (coracoid fracture)

Type III scapular fracture

Comminuted, type III scapular fracture

Shoulder: Dislocation

Classification

Anterior (95-97%) Subcoracoid (most common) Subglenoid

(1/3 associated with # greater tuberosity, or # glenoid rim)

Subclavicular Intrathoracic Also important to note primary vs. recurrent

Anterior dislocation - subcoracoid

Shoulder: Dislocation

Classification – cont’d

PosteriorSubacromial (98% of posterior dislocations)SubglenoidSubspinous

Inferior (Luxatio Erecta) - raresuperior - rare

Shoulder: Dislocation

Signs of posterior shoulder dislocation:

↑distance from anterior glenoid rim and humeral head “rim” sign

Humeral head internally rotated “Light bulb” or “drum stick” sign

True AP shows humeral/glenoid overlap

Impaction # of the anteromedial humeral head “reverse Hill-Sachs deformity” “Trough sign”

Posterior dislocationArrow = impaction # of anteromedial humeral head

Posterior dislocationNote the humeral head roatation

Posterior dislocation – lateral view

Posterior dislocation – axillary view

Shoulder: Dislocation

Associated fractures:

1. Compression # of the posterolateral aspect of the humeral head “Hill-Sachs deformity” 11-50% of anterior dislocations

2. Anterior glenoid rim fracture “Bankart’s fracture” ~5% of cases

3. Avulsion fracture of the greater tuberosity ~10-15% of cases

Anterior dislocationArrow = # of the posterolateral aspect of humerus

Post-reduction filmAvulsion # of the greater tuberosity

Shoulder

Practice

Clavicle fracture – distal third – type II

Scapula fracture – type III

AC separation - grade I

Anterior shoulder dislocation

Posterior dislocation (False AP – note overlap)