This is Important radio-logical classification of fracture and AVN, I made this from various references like radiopaedia and radiology website , It will help for radiology resident, radiologist and even orthopedics resident. Thanks.

1. Important radiological classification of fracture and AVN
Schatzker classification system is one method of classifying tibial
plateau fractures.
Increase in type number denotes increasing severity, reflecting an
increase in energy imparted to the bone at the time of injury and also an
increasingly worse prognosis 1. The most common fracture of the tibial
plateau is type II.
Classification
This system divides tibial plateau fractures into six types:
 Schatzker I: wedge-shaped pure cleavage fracture of the lateral tibial
plateau, originally defined as having less than 4 mm of depression or
displacement
 Schatzker II: splitting and depression of the lateral tibial plateau;
namely, type I fracture with a depressed component
 Schatzker III: pure depression of the lateral tibial plateau; divided
into two subtypes:
o Schatzker IIIa: with lateral depression
o Schatzker IIIb: with central depression
 Schatzker IV: medial tibial plateau fracture with a split or depressed
component
 Schatzker V: wedge fracture of both lateral and medial tibial plateau
 Schatzker VI: transverse tibial metadiaphyseal fracture, along with
any type of tibial plateau fracture (metaphyseal-diaphyseal
discontinuity)

2. Calcaneal fracture
Calcaneal fractures are the most common tarsal fracture and can
occur in a variety of settings.
Epidemiology
The calcaneus is the most commonly fractured tarsal bone and
accounts for about 2% of all fractures and ~60% of all tarsal
fractures 3.
Pathology
Calcaneal fractures can be divided broadly into two types depending
on whether there is articular involvement of the subtalar joint
1. extra-articular: 25-30%
o anterior calcaneal process fracture
o calcaneal tuberosity avulsion fracture
o extra-articular body fracture

3.  lover's fracture
o medial sustentaculum
2. intra-articular: 70-75%
o intra-articular body fracture
The calcaneus is also a common site of stress fractures, occurring in
the posterosuperior aspect.
Another method of classification is as
 type A fractures: the anterior process of the calcaneus is
fractured
 type B: fracture of the mid calcaneus, trochlear process, and
sustentaculum tali
 type C: fracture of the posterior tuberosity
Radiographic features
Plain radiograph
 Böhler's angle is the angle between two tangent lines drawn
across the anterior and posterior borders of the calcaneus in the
lateral view. When Böhler's angle becomes <20º it indicates a
calcaneal fracture. On a lateral radiograph, an angle of Gissane of
>130° suggests depression of the posterior facet of the subtalar
joint.
 normal Böhler's angle does not exclude a fracture and is
unreliable in children 9
 calcaneal stress fracture shows vertical linear sclerotic
appearance 9
CT
CT is the modality of choice to evaluate calcaneal fracture. It can
show the extent and extra- or intra-articular components of the
fracture and haematoma along the sole of the foot (Mondor
sign). Intra-articular fractures are often classified using the Sander
classification system, which is one of the only systems that correlate
well with patient outcome.
Practical points

4. If bilateral calcaneal fractures are seen, then the spine should also
be evaluated for fracture as the mechanism of injury is often a large
load to the axial skeleton, such as jumping from a second-story
window.
If an intraarticular calcaneal fracture is seen, the images should be
scrutinized for a lateral malleolar fleck sign (ankle), which raises the
likelihood of peroneal tendon instability

5.  type 1: includes all intraarticular fractures that have less than 2 mm of
articular displacement, regardless of the number of fracture
lines/fragments present
 type 2a: involves one primary fracture line that courses through the
lateral aspect of the posterior facet; the primary fracture usually
assumes a "y" shaped configuration as it exits medially and laterally
out of the calcaneal body; this fracture is often accompanied by one or
more accessory fracture lines that do not involve the posterior articular
facet
 type 2b: involves one primary fracture line that courses through the
central aspect of the posterior facet; the primary fracture usually
assumes a "y" shaped configuration as it exits medially and laterally
out of the calcaneal body; this fracture is often accompanied by one or
more accessory fracture lines that do not involve the posterior articular
facet

6.  type 2c: involves one primary fracture line that courses through the
medial aspect of the posterior facet and is accompanied by a transverse
fracture through the body of the calcaneus; this fracture is often
accompanied by one or more accessory fracture lines that do not
involve the posterior articular facet
 type 3ab: involves two primary fracture lines, one coursing through
the lateral aspect of the posterior facet and the second through the
central aspect; this subtype usually presents with depression of the
central fragment; the two primary fracture lines may be accompanied
by additional accessory fracture lines that do not involve the posterior
articular facet
 type 3ac: involves two primary fracture lines, one coursing through
the lateral aspect of the posterior facet and the second through the
medial aspect; this subtype usually presents with depression of the
central fragment. The two primary fracture lines may be accompanied
by additional accessory fracture lines that do not involve the posterior
articular facet
 type 3bc: involves two primary fracture lines, one coursing through
the central aspect of the posterior facet and the second through the
medial aspect; this subtype usually presents with depression of the
central fragment; the two primary fracture lines may be accompanied
by additional accessory fracture lines that do not involve the posterior
articular facet
 type 4: involves three or more primary fracture lines with greater than
2 mm of articular displacement, and are therefore severely
comminuted
Acetabular fracture
Classification
The Judet and Letournel system for acetabular fractures is the most
widely used classification system in clinical practice. It classifies fracture
based on oblique pelvic view on plain radiographs.
Additional classification systems include:
 Orthopaedic Trauma Association classification (primarily for research)
 Harris system (CT imaging based)
Radiographic features

7. Plain radiograph
Initial assessment is often with a portable AP radiograph of the pelvis in
the emergency department.
Assess the following lines:
1. anterior acetabular wall
2. posterior acetabular wall
3. acetabular roof
4. iliopectineal line: disrupted in fractures involving the anterior column
5. ilioischial line: disrupted in fractures involving the posterior column
6. radiographic U (teardrop)
After diagnosis, oblique pelvic views (Judet views) may be used for follow
up. These include:
1. iliac oblique view for the posterior pelvic column and anterior
acetabular wall
2. obturator oblique view for the anterior pelvic column and posterior
acetabular wall
CT
CT has revolutionised the diagnosis, enabling precise delineation of the
fracture configuration and assessment of any articular surface disruption.
Many patients with high-energy trauma will have a whole body CT,
allowing initial assessment of the femoroacetabular joint as well as any
other injuries that are likely to be present, given the typically high energy
mechanism of injury 2.
For those patients with pelvic insufficiency fractures involving the
acetabulum, a standard CT with a bony algorithm may be useful,
especially if operative management is under consideration.
A repeat CT after traction is sometimes used to assess response to
treatment.
Treatment and prognosis
Treatment
 analgesia
 venous thromboembolism prophylaxis
 traction

8. o skin traction
o skeletal traction
 non-operative management
o may be indicated in the setting of minimally displaced fracture
o more common in developing countries
 open reduction and internal fixation (ORIF)
o articular incongruence/displaced fracture
o significantly distorted acetabular roof arc
o entrapped intra-articular fragment
o subluxation of the femoral head

10. The Judet and Letournel classification is more widely used and is
applicable to both CT and plain radiographs, whereas, the Harris
classification is applicable to CT only .
Classification
The Harris classification defines acetabular fractures in four categories :
 category 0: anterior wall or posterior wall only
 category 1: single-column fractures
 category 2: both columns (i.e. transverse)
o 2a: no extension
o 2b: superior extension
o 2c: inferior extension
o 2d: superior and inferior extension
 category 3: acetabular dissociated from the axial skeleton
Avascular necrosis (AVN), or more correctly osteonecrosis, is a
generic term referring to the ischaemic death of the constituents of bone.
AVN has a wide variety of causes and can affect nearly any bone in the
body. Most sites of involvement have an eponym associated with
avascular necrosis of that area, and these sites are discussed individually
as each site has unique clinical, aetiologic and prognostic features.
Eponymous names for specific sites of avascular
necrosis
 Ahlback disease: medial femoral condyle, i.e. SONK
 Brailsford disease: head of the radius
 Buchman disease: iliac crest
 Burns disease: distal ulna
 Caffey disease: entire carpus or intercondylar spines of the tibia
 Dias disease: trochlea of the talus
 Dietrich disease: head of metacarpals
 Freiberg infraction: head of the second metatarsal
 Friedrich disease: medial clavicle
 Hass disease: humeral head
 Iselin disease: base of 5th metatarsal
 Kienböck disease: lunate

11.  Köhler disease: patella or navicular (children)
 Kümmell disease: vertebral body
 Legg-Calvé-Perthes disease: femoral head
 Mandl disease: greater trochanter
 Mauclaire disease: metacarpal heads
 Milch disease: ischial apophysis
 Mueller-Weiss disease: navicular (adult)
 Panner disease: capitellum of the humerus
 Pierson disease: symphysis pubis
 Preiser disease: scaphoid
 Sever disease: calcaneal epiphysis
 Siffert-Arkin disease: distal tibia
 Thiemann disease: base of phalanges
 van Neck-Odelberg disease: ischiopubic synchondrosis
Radiographic features
Radiographic changes alter with the stage of AVN - Ficat staging, Steinberg classification.
Radiograph
In general, there is initial minor osteopenia, followed by variable density.
Gradually microfractures of the subchondral bone accumulate in the dead
bone, which is unable to repair leading to the collapse of the articular
surface and the crescent sign of AVN. Eventually the cortex collapses and
fragments, with superimposed secondary degenerative change.
MRI
MRI is the most sensitive (~95%) modality and demonstrates changes
well before plain films changes are visible.
 reactive interface line: focal serpentine low signal line with fatty centre
(most common appearance and first sign on MRI)
 double line sign: serpentine peripheral/outer dark (sclerosis) and inner
bright (granulation tissue) on T2WI is diagnostic
 diffuse oedema: oedema is not an early sign; instead, studies show
that oedema occurs in advanced stages and is directly correlated with
pain
 rim sign: osteochondral fragmentation
 secondary degenerative change (i.e. osteoarthritis)

12. Nuclear medicine
Bone scintigraphy is also quite sensitive (~85%) and is the second option
after MRI. It is a choice when multiple sites of involvement must be
assessed in patients with risk factors, such as sickle cell disease. The
findings are different accordingly to the time of the scan:
 early disease: often represented by a cold area likely representing the
vascular interruption
 late disease: may show a "doughnut sign": a cold spot with
surrounding high uptake ring (surrounding hyperaemia and adjacent
synovitis)

13. Steinbergclassification
 Modic type I
o T1: low signal
o T2: high signal
o represents bone marrow oedema and inflammation
o T1+C: enhancement

14.  Modic type II
o T1: high signal
o T2: iso to high signal
o represents normal red haemopoietic bone marrow conversion into
yellow fatty marrow as a result of marrow ischaemia
 Modic type III
o T1: low signal
o T2: low signal
o represents subchondral bony sclerosis
Acromioclavicularinjury
Acromioclavicular joint injuries are characterised by damage to
the acromioclavicular joint and surrounding structures. Almost
invariably traumatic in aetiology, they range in severity from a mild
sprain to complete disruption.
Clinical presentation
Acromioclavicular joint injuries usually occur from a direct blow or
following a fall onto the shoulder with an adducted arm. This pushes
the acromion forcibly inferiorly and medially with respect to the
clavicle 7.
Radiographic features
Imaging can be used to classify acromioclavicular injuries, with
the Rockwood system most commonly used to classify injuries into

15. six types. Other described systems include the Tossy and the Allman
classification systems.
In most cases, plain films (including an axillary view) are sufficient
for accurate grading although CT or MRI may be useful in cases
where plain films are thought to underrepresent the degree of
injury.
Plain radiograph
Standard acromioclavicular joint radiographs consist of a clavicle
series including an AP and cephalic angled oblique (10-15º) views.
Additional weight-bearing stress views may be of benefit if:
 initial radiographs are normal, but an injury is suspected
 surgical intervention on a type III injury would be contemplated
(see below)
These are performed with the patient erect and holding a weight in
the arm. If the joint is normal, then acromioclavicular alignment
should remain normal and symmetric.
Features of acromioclavicular joint injury include 6:
 soft tissue swelling/stranding
o may be the only finding in type I injuries
 widening of the acromioclavicular joint
o normal: 5-8 mm (narrower in the elderly)
o greater than 2-4 mm asymmetry (compared to radiographs of
the contralateral side)
 increased coracoclavicular distance
o normal: 10-13 mm
o greater than 5 mm asymmetry (compared to the contralateral
side)
 superior displacement of the distal clavicle
o the inferior edge of the acromion should be level with the
inferior edge of the clavicle

16. Slipped upper femoral epiphysis
Slipped upper femoral epiphysis (SUFE), also known as
a slipped capital femoral epiphysis (SCFE), (plural:
epiphyses) is a relatively common condition affecting the physis of
the proximal femur in adolescents. It is one of the commonest hip
abnormalities in adolescence and is bilateral in ~20% of cases.
Epidemiology
Slipped upper femoral epiphysis is more common in boys than girls
and more common in Afro-Caribbeans than Caucasians. The age of
presentation is somewhat dependant on gender with boys
presenting later (10-17 years) than girls (8-15 years) 2. Obesity is a
significant risk factor.

17. Clinical presentation
Patients present with hip pain progressing to a limp and even leg
length discrepancy.
If slipped upper femoral epiphysis is confirmed on imaging, the child
should be rested, admitted, and not allowed to weight-bear.
Pathology
Slipped upper femoral epiphysis is a type I Salter-Harris growth
plate injury due to repeated trauma on a background of mechanical
and probably hormonal predisposing factors.
Radiographic features
In all situations, especially when imaging children, the fewest number of radiographs, with
the smallest exposed area is performed. Gonad protection is usually used in pelvic x-rays of
children. However, there should always be one radiograph without the lead protection so that
the entire pelvis is visualised.
Plain radiograph
The radiographs that are used will depend on the institution where you
work:
 AP and frog-leg: the commonest situation allows assessment of two
views
 AP only: a perceived concern about a risk of worsening a slip means
that a frog-leg lateral is only performed if the orthopaedic surgeon or
radiologist agrees
 frog-leg only: to reduce the dose, only frog-leg lateral is performed
because it is this view that is most sensitive and the AP rarely adds
diagnostic information
The slip that occurs is posterior and, to a lesser extent, medial. It is
therefore is more easily seen on the frog-leg lateral view rather than the
AP hip view. Because the epiphysis moves posteriorly, it appears smaller
because of projectional factors.
On the AP, a line drawn up the lateral edge of the femoral neck (line of
Klein) fails to intersect the epiphysis during the acute phase (Trethowan
sign).
The metaphysis is displaced laterally and therefore may not overlap
posterior lip of the acetabulum as it should normally (loss of triangular
sign of Capener) .

18. The metaphyseal blanch sign, a sign seen on AP views, involves increases
in the density of the proximal metaphysis. It represents the superposition
of the femoral neck and the posteriorly displaced capital epiphysis.
Alignment of the epiphysis with respect to the femoral metaphysis can be
used to grade the degree of slippage:.
MRI
In the acute stage, marrow oedema results in an increased signal on T2-
weighted sequences, e.g. STIR. Marrow oedema is non-specific, and while
it may indicate early bone changes in SUFE, there are numerous other
causes, e.g. infection or a tumour.
MRI can be used to examine the contralateral hip which is important
because of the high incidence of bilateral slip.
 STIR
o high signal in epiphysis and metaphysis
o joint effusion
 T1
o low signal in oedematous regions
o metaphyseal displacement
n an AP radiograph a line along the superior margin of the femoral neck
(line of Klein) should intersect the lateral corner of the epiphysis.
As the epiphysis slips, the metaphysis can be divided into thirds.
 mild: lateral edge of epiphysis is within the lateral third of the
metaphysis

19.  moderate: middle third
 severe: medial third
On a true lateral radiograph, the angle (slip angle) which the epiphysis
makes with the metaphysis may also be employed (sometimes known as
the Southwick head shaft angle).
 normal: ~0 degrees
 mild: 0-30 degrees
 moderate: 30-60 degrees
 severe: >60 degrees
Perthes disease
Perthes disease, also known as Legg-Calvé-Perthes disease,
refers to idiopathic osteonecrosis of the femoral epiphysis seen in
children. It should not be confused with Perthes lesion of the
shoulder.
It is a diagnosis of exclusion and other causes of osteonecrosis
(including sickle cell disease, leukaemia, corticosteroid
administration, Gaucher disease) must be ruled out .
Epidemiology
Perthes disease is relatively uncommon and in Western populations
has an incidence approaching 5 to 15:100,000.
Boys are five times more likely to be affected than girls.
Presentation is typically at a younger age than slipped upper
femoral epiphysis (SUFE) with peak presentation at 5-6 years, but
confidence intervals are as wide as 2-14 years .
Perthes is considered an idiopathic condition, and there are no clear
predisposing factors.
Clinical presentation
Most children present with atraumatic hip pain or limp. Some
children have a coincidental history of trauma. This may precipitate
the presentation or the realisation of symptoms that in fact had
been long-standing.

20. Blood tests are typically normal in Perthes. It is important to be
certain that there is no other cause of osteonecrosis (e.g. sickle cell
disease) during the workup.
Pathology
The specific cause of osteonecrosis in Perthes disease is unclear.
Osteonecrosis generally occurs secondary to the abnormal or
damaged blood supply to the femoral epiphysis, leading to
fragmentation, bone loss, and eventual structural collapse of the
femoral head. In approximately 15% of cases, osteonecrosis occurs
bilaterally.
Radiographic features
The best initial test for the diagnosis of Perthes is a pelvic
radiograph. In a small number of patients with Perthes, the
radiograph will be normal and persistent symptoms will trigger
further imaging, e.g. MRI.
The investigation of atraumatic limp will often include a hip
ultrasound to look for effusion, but ultrasound is unlikely to pick up
osteonecrosis.
The radiographic findings are those of osteonecrosis. There are
separate systems for staging of Perthes disease:
 temporal evolution
o Waldenström classification
o modified Elizabethtown classification
 severity and prognosis
o Catterall classification: extent of femoral head involvement
o Salter-Thompson classification: extent of femoral head
involvement
o Herring classification: lateral pillar involvement
 healed stage deformity: osteoarthritis risk
o Stulberg classification

21. Plain radiograph
The radiographic changes to the femoral epiphyses depend on the
severity of osteonecrosis and the amount of time that there has
been an alteration of blood supply:
 early: there may be no appreciable change
 established: reduction in epiphysis size, lucency
 late: fragmentation, destruction
As changes progress, the width of the femoral neck increases (coxa
magna) in order to increase weight-bearing support.
Early signs
 joint effusion: widening of the medial joint space
 asymmetrical femoral epiphyseal size (smaller on the affected
side)
 apparent increased density of the femoral head epiphysis
 blurring of the physeal plate (stage 1)
 radiolucency of the proximal metaphysis
Late signs
Eventually, the femoral head begins to fragment (stage 2), with
subchondral lucency (crescent sign) and redistribution of weight-
bearing stresses leading to thickening of some trabeculae which
become more prominent.
The typical findings of advanced burnt out (stage 4) Perthes disease
are:
 femoral head deformity with widening and flattening (coxa plana)
 proximal femoral neck deformity: coxa magna
 "sagging rope sign" (thin sclerotic line running across the femoral
neck)
Additionally, tongues of cartilage sometimes extend inferolaterally
into the femoral neck, creating lucencies, which must be
distinguished from infection or neoplastic lesions 4. The presence of
metaphyseal involvement not only increases the likelihood of
femoral neck deformity but also make early physeal closure with
resulting leg length disparity more likely.

22. Arthrography
Traditionally arthrography performed under general anaesthesia
with conventional fluoroscopy is performed to assess congruence
between the femoral head and the acetabulum in a variety of
positions . MRI is increasingly replacing this, in an effort to eliminate
pelvic irradiation.
MRI
MRI is gaining an increasing role in a number of scenarios:
 early diagnosis, before the onset of x-ray findings
 assessing the extent of cartilaginous involvement, important in
prognosis
 assessing joint congruence in a variety of joint positions (requires
open magnet and dynamic imaging) 2
Both arthrography and dynamic MRI assess three main features :
 deformity of the femoral head (also assessed on static x-rays and
MRI)
 congruence: how well the femoral head contour matches that of
the acetabulum
 containment: the amount of lateral subluxation of the flattened
femoral head out of the acetabulum
o when severe this may lead to hinge abduction, whereby rather
than rotation and medial movement of the femoral head during
hip abduction, the flattened head 'hinges' on the lateral lip of
the acetabulum, widening the medial joint space 2,3
here are several classification systems for sacral fractures, but the
most commonly employed are the Denis classification and
subclassification systems, and the Isler classification system. These
classification systems are important to understand as proper classification
can impact management.
AO classification of sacral injuries
 type A: lower sacrococcygeal injuries

23.  type B: posterior pelvic injuries
 type C: spinopelvic injuries
The AO sacral injury classification further subdivides these three injury
types and also involves neurological and other modifiers that can be
added.
Denis classification
 zone 1: fracture involves the sacral ala lateral to the neural foramina
 zone 2: fracture involves the neural foramina, but does not involve the
spinal canal
 zone 3: fracture is medial to the neural foramen, involving the spinal
canal; these may be transverse or longitudinal, and can be sub-
classified into 4 types:
o type 1: only kyphotic angulation at the fracture site (no translation)
o type 2: kyphotic angulation with anterior translation of the distal
sacrum
o type 3: kyphotic angulation with complete offset of the fracture
fragments
o type 4: comminuted S1 segment, usually due to axial compression
Morphologic injury patterns of zone 3 fractures
 “H” shaped fracture
 “U” shaped fracture
 “ʎ” (lambda) shaped fracture
 “T” shaped fracture
Isler classification
Used for fractures that involve the lumbosacral articulation:
 Isler 1: fracture occurs lateral to the L5/S1 facet
 Isler 2: fractures line involves the L5/S1 facet
 Isler 3: fracture line extends medially to the L5/S1 facet