The document provides detailed information on various types of joint dislocations, including shoulder, elbow, wrist, hip, and knee dislocations, along with their associated injuries and complications. It describes the anatomical positions and radiographic findings of dislocations, potential fractures, and associated soft tissue injuries. Diagnostic measures and classifications for conditions like acromioclavicular and sternoclavicular dislocations are also discussed, alongside mechanisms of injury and clinical implications.

1. Dislocations Of Joint
Dr Muhammad Bin Zulfiqar
PGR III FCPS Services Hospital/Services Institute of Medical
Sciences

2. Shoulder - Anterior dislocation - AP view
• The humeral head is dislocated from the
glenoid of the scapula and is now located
inferior to the coracoid process of the scapula.

4. Shoulder -
Anterior
dislocation - Y-
view
• The dislocated
humeral head is
located anterior
to the glenoid
and inferior to
the coracoid
process.

6. • Shoulder - Anterior dislocation - Axial view
• The dislocated humeral head is positioned
anterior to the glenoid fossa.

7. • Shoulder - Anterior dislocation/ humerus
fracture
• This shoulder dislocation is complicated by a
fracture of the humeral head.

8. • Shoulder - Anterior
dislocation/Hill-
Sachs lesion
• Flattening or
indentation of the
posterior humeral
head following
shoulder dislocation
is known as a 'Hill-
Sachs' lesion.
• In this case the
humeral head is
impacted on the
anterior rim of the
glenoid.

9. • Shoulder - Anterior
dislocation/ glenoid
fracture
• The humeral head has
been relocated
following an anterior
dislocation. A fragment
of bone is visible at the
anterior-inferior edge
of the glenoid.
• A fracture of the
anterior glenoid
following shoulder
dislocation is known as
a 'bony Bankhart'
lesion.

10. • Right image shows humeral head displaced from glenoid
and lying inferior to the coracoid process (red arrow);
• the middle image demonstrates a defect along the
posterolateral aspect of the head, which is the Hill-Sach's
deformity (green arrow).
• The Left image is the scapular Y view (blue line outlines
scapula). The head lies in a subcoracoid (i.e. anterior
location).

11. • Shoulder - Posterior dislocation - AP
• The glenohumeral joint is widened (arrowheads) and
the humeral head has taken on a more rounded 'light
bulb' shape. These are typical appearances of a
posterior glenohumeral dislocation.

12. • Shoulder - Posterior
dislocation - Y-view
• The humeral head is
posteriorly
positioned in
relation to the
glenoid.

13. Inferior Shoulder Dislocation
• LUXATIO ERECT A
• = extremity held over head in fixed position
with elbow flexed.
• Mechanism: severe hyperabduction of arm
resulting in impingement of humeral head
against acromion
• Humeral articular surface faces inferiorly

14. • Anteroposterior radiograph shows luxatio erecta, or inferior
dislocation of the shoulder. The arm is abducted, elevated, and
fixed. The humeral head is subcoracoid in position, with a parallel
humeral shaft and a parallel scapular spine. An associated greater
tuberosity fracture is present.

15. Acromioclavicular Dislocation (12%)
• Grade 4 (posterior dislocation)
• Posterior position of clavicle with respect to
acromion
• Grade 5 (fascial injury)
• Penetration of clavicle through deltotrapezial
fascia
• Grade 6 (inferior dislocation)
• Inferior position of clavicle with respect to
acromion

16. Acromioclavicular Dislocation (12%)
• Grade 1 (strain)
• = stretching / partial tearing of acromioclavicular ligament fibers
• Soft-tissue swelling, stable AC joint without joint widening
• Grade 2 (subluxation)
• = disruption of acromioclavicular ligament+ strain of
coracoclavicular ligament
• Elevation of clavicle of <100% of shaft width (weight bearing!)
widening of AC joint
• Grade 3 (superior dislocation)
• = disruption of acromioclavicular + coracoclavicular
• ligaments
• Widening of AC joint, elevation of clavicle > 100% of shaft width

17. Normal measurements
• AC joint space is usually <5mm
– Right and left differ by no more than 2-3 mm
• Coracoclavicular distance usually <11-13 mm
– Right and left should differ by < 5 mm
• 50% difference in size between the two shoulders is considered
significant
• Inferior plane of the distal clavicle should be on same plane as
inferior border of acromion
– Developmental variations reported as high as 19%
• Fall on shoulder is frequent mechanism of injury Point tenderness,
limitation of motion
• Abnormal widening of the AC joint due to disruption of the AC
ligament CC separation is the more important soft tissue injury
• Extent of CC separation has direct effect on degree of AC separation

18. • Mild asymmetric widening of the right AC joint
(7mm). CC distance is symmetrical. No
displacement. No fracture.

19. • GRADE II : Anteroposterior radiograph shows
widening of acromioclavicular interspace
(ellipse) without clavicular displacement.

20. • GRADE II: Anteroposterior radiograph
apparently shows 50% superior clavicular
displacement, but acromioclavicular joint
interspace (ellipse) appears to be normal.

21. • GRADE III Two views of right shoulder show elevation of the clavicle
and separation of the AC joint in a Type III AC joint separation

22. • GRADE V: Dislocation of the left acromioclavicular
joint, with the clavicle displaced superiorly and
widening of the coracoclavicular space (25 mm),
consistent with coracoclavicular ligament
injury/rupture. This is a grade V injury. Grossly
enlocated glenohumeral joint. No fractures
detected.

23. Sternoclavicular Joint Dislocation
• POSTERIOR STERNOCLAVICULAR DISLOCATION
• = posterior displacement of head of clavicle
• Cause: blow to shoulder I medial clavicle
• Cx: injury to mediastinal blood vessels, trachea,
esophagus
• ANTERIOR STERNOCLAVICULAR DISLOCATION
• = anterior displacement of head of clavicle (more
common)
• Cause: anterior blow to shoulder
• Protruding clavicular head can be palpated
• Cx: chronic pain, ankylosis, deformity
• Rx: conservative therapy

24. • Right Posterior Sternoclavicular Joint
Dislocation

25. • Preoperative (a) X-ray and (b) 3D CT reconstruction showing anterosuperior
dislocation of the sternoclavicular joint and superioposterior dislocation of
acromioclavicular joint

26. • Manubriosternal
Joint Subluxation is
seen.

27. • Posterior
manubriosternal
Joint dislocation is
seen.

28. Elbow Dislocation
• Elbow dislocation is the second most common
large joint dislocation in the adult population.
• A dislocation with no fracture is simple whereas
an accompanying fracture makes the
dislocation complex. The most common fracture
is a radial head fracture, although coronoid
process fracture is also common. The terrible
triad of the elbow is the combination of 1-3:
• posterior dislocation
• coronoid process fracture
• radial head fracture

29. • Elbow dislocation - Lateral
• The ulna has dislocated posteriorly from the trochlea of the
humerus. The radius has dislocated from the capitulum of the
humerus.
• The roll-over image shows the normal position post-reduction.

30. • Elbow dislocation -
AP
• The same injury is
shown on the AP
view.
• The roll-over image
shows the normal
position post-
reduction and
reveals a fracture.

31. • X ray show posterior dislocation of the elbow

32. • Posterior Elbow Dislocation with radial neck
fracture

33. • Posterior dislocation of the elbow with
associated fracture of the coronoid process.

34. • Posterior elbow dislocation with fracture of the
coronoid process and radial head fracture.
• Given the poor prognosis for such injuries, they
have been given the name of the "terrible triad of
the elbow".

35. • There is medial dislocation of proximal end of
radius - ulna along with fracture of medial
epicondyle.

36. • Fracture dislocation of the elbow. Note the
fracture of the lateral condyle.

37. • Fracture dislocation of the elbow with
avulsion of the medial epicondyle.

38. Wrist I Carpal Dislocation
• Mechanism: fall on outstretched hand
• Incidence: 10% of all carpal injuries
• 0 Up to 25% overlooked at initial examination!

39. Lunate Dislocation
• = final stage of peri lunate injury with highest
degree of instablity
• Spilled teacup sign = lunate dislocated in volar
direction (on LAT view)
• Rest of carpus assumes alignment with radius

40. • There is fracture of the ulnar styloid. On the AP
projection there is disruption of the normal alignment
of the proximal carpal row with the lunate appearing
triangular in shape and superimposed over the
capitate. Lunate dislocation is confirmed on the lateral
film.

42. Perilunate Dislocation
• = dislocation of capitate head from concavity of distal lunate
• Prevalence: 2-3 times more common than lunate dislocation
• Mechanism: high-energy wrist hyperextension (MVC, fall from
height, sports) with sequential injury of scapholunate to
lunocapitate to lunotriquetral joints to complete dislocation
• Average age: 30 years; M >> F
• Associated with: fracture in 75%
• Disruption of carpal arcs (AP view)
• Terry-Thomas sign= widening of space between scaphoid and
lunate (AP view)
• Triangular lunate (AP view)
• Posterior dislocation of capitate head relative to lunate
• (LAT view)

45. Rotary Subluxation of Scaphoid
• = SCAPHOLUNATE DISSOCIATION = tearing of
interosseous ligaments of lunate, scaphoid,
capitate
• Mechanism: acute dorsiflexion of wrist; may
be associated with rheumatoid arthritis
• Gap >4 mm between scaphoid +lunate (PA
view)
• Foreshortening of scaphoid
• Ring sign of distal pole of scaphoid

46. • There is an intra-articular radial styloid fracture. Importantly there
is widening of the scapholunate distance (Terry Thomas
sign) consistent with scapholunate dissociation. This represents a
surgically significant ligamentous injury.

47. • A, Posteroanterior view of wrist shows abnormal configuration of
lunate (dashed lines), which is referred to as “piece-of-pie” sign. B,
Lateral radiograph of wrist shows loss of colinearity of radius,
lunate, and capitate (dashed line). Lunate (solid arrow) is volarly
tilted and volarly subluxed. Capitate (dotted arrow) is dorsally
subluxed. All these findings are consistent with midcarpal and
central carpal dislocation.

48. LESSER ARC INJURY
• = pure ligamentous disruption around lunate
• Most commonly dorsal dislocation
• Rx: open reduction+ internal fixation

49. • Lesser arc perilunate
dislocation. (a, b) Frontal
radiograph (a) and 3D CT
image (b) show a triangular
appearance of the lunate
(*), disruption of Gilula arcs
I and II, and a small avulsion
fracture (arrow) in the
scapholunocapitate space.
(c, d) Lateral radiograph (c)
and sagittal reformatted CT
image (d) show dorsal
dislocation of the rest of the
carpal bones along with the
hand relative to the lunate
(*). Note the associated
triquetral fracture (arrow
in c).

50. GREATER ARC INJURY
• = peri lunate dislocation+ fracture of scaphoid
I trapezium I capitate I hamate I triquetrum
• Twice as common as lesser arc injury
• Most commonly transscaphoid peri lunate
dislocation
• Fracture of any carpal bone around lunate

51. • Greater Arch Injury: Transscaphoid perilunate
dislocation. Frontal (a) and lateral (b)
radiographs and 3D CT images (c, d) show
disruption of Gilula arcs I and II, a triangular
lunate (*), and dorsal dislocation of the rest of
the carpal bones along with the hand relative to
the lunate, findings consistent with perilunate
dislocation. In addition, there is a displaced
fracture of the scaphoid waist (large arrow), an
avulsion fracture of the lunate (small arrow in a
and c), and a fracture of the ulnar styloid
process.

52. Hip dislocation
• Hip dislocation (dislocation of the femoral head
from the acetabulum) is most frequent following
total hip replacement (THR). Dislocation is usually
in a posterior direction which clinically leads to
leg shortening, with flexion and internal rotation
at the hip (note - hip fractures usually cause
external rotation).
• Hip dislocation may be accompanied by fracture
of the acetabulum, or significant soft tissue
injuries not visible with X-ray.

53. • Standard views
• Anterior-Posterior (AP) pelvis and Lateral hip.
Both views should be carefully viewed to look
for an accompanying fracture of the
acetabular rim.
• Key points
• Hip dislocation can be accompanied by
fractures, or soft tissue injury not visible with
X-ray

54. • Hip dislocation - AP
• The femoral head lies superior and lateral to the
acetabulum
• No associated fracture is visible in this case but significant
soft tissue injury is likely

55. • Posterior fracture-dislocation,
hip. Anteroposterior
conventional radiograph of the
pelvis (above) shows
that right femoral head (blue
arrow) lies more superior than
the superior rim of the
acetabulum (white arrow). The
normal left femoral head
appears slightly larger than the
posteriorly dislocated right
because it is farther from the
imaging surface and more
magnified. The contrast in the
bladder was injected
intravenously for a CT scan. The
CT scan of the pelvis (below)
demonstrates the femoral head
(red arrow) well posterior to
the acetabulum. There are
associated fractures of the
posterior rim of the
acetabulum (yellow arrow).

56. • Hip dislocation - Dislocated THR
• Patient with Total Hip Replacement (THR)
• The ball of the femoral component is
displaced from the cup of the acetabular
component

57. Posterior Hip Dislocation

58. Anterior Hip Dislocation
• Posterior hip dislocations are much more common
than anterior hip dislocations (90% to about 10%)
• In anterior dislocations, the head of the femur usually
rests inferior and medial to its normal acetabular
position, frequently overlying the obturator foramen
(inferior type of anterior dislocation) Some anterior
dislocations the femoral head may lie superior to the
acetabulum (superior type of anterior dislocation)
These occur when mechanism is abduction, external
rotation, and extension rather than flexion of the leg
• The superior type of anterior dislocation may be
confused with a posterior dislocation

59. • Anterior Hip Dislocation. The right femoral head (blue
arrow) overlies the obturator foramen, inferior and medial
to its normal location in the acetabulum (white arrow).

60. Dislocation of the Knee
• Uncommon dislocation Most are either anterior or
posterior Using the position of the tibia as the reference
Anterior dislocations (most frequent)
– Hyperextension
– Posterior dislocations (second most frequent)
• Force to anterior tibia with knee flexed as in MVC or falls
– Medial, lateral or rotational
• Valgus, varus or rotational forces
– As many as 50% of knee dislocations spontaneously self-reduce
• Can lead to underestimation of damage
• Most believe that dislocation requires injury to both
anterior and posterior cruciate ligaments and either of the
collateral ligaments

61. • Posterior and Lateral Dislocation of Knee. The tibia is displaced
laterally and posteriorly relative to the femur (red arrow). The
patella is displaced laterally (black and white arrows) and comes to
lie over the lateral femoral condyle. Some degree of rotational force
is usually required to produce this type of injury.

62. • A, Supine anteroposterior and lateral radiographs of
right knee show mild posterolateral subluxation of
tibiofemoral articulation and subtle widening of
medial joint space (solid arrow). There is mild lateral
patellar subluxation (open arrow) and large knee joint
effusion (asterisk).

63. • Radiograph shows anterior knee dislocation in
21-year-old man.

64. • Radiograph shows anterolateral rotational
knee dislocation in 38-year-old man.

65. • A, Supine anteroposterior and cross-table lateral
radiographs of left knee show depressed medial tibial
plateau fracture (thick arrows) and displaced avulsion
fracture of fibular
• head (thin arrow). There is slight lateral subluxation of
tibia. There is small bone fragment in region of tibial spines
and anterior cruciate ligament (ACL) footprint (open arrow).

66. • A, Supine anteroposterior and lateral radiographs of
left knee show lateral dislocation of tibiofemoral
joint. Small capsular avulsions are projected posterior
to femoral condyles on lateral examination (black
arrow), and there is small bone fragment adjacent to
lateral femoral condyle (white arrow). Note irregularity
of medial femoral condyle (arrowhead).

67. • Cross-table lateral and anteroposterior
radiographs show posterolateral dislocation of
tibiofemoral articulation and lateral
dislocation of patella (asterisks).

68. • A, Cross-table lateral and anteroposterior
radiographs of left knee show posteromedial
dislocation of tibiofemoral joint. Note artifact
from overlying splint and soft-tissue gas
(arrows).

69. Patella Alta
• Patella alta (or a high riding patella) describes a
situation where the position of the patella is
considered high. It may be idiopathic or may result
secondary to a patellar tendon rupture.
• Associations
• Several conditions are known to be associated with
patella alta, including:
• idiopathic retropatellar pain
• recurrent dislocation of the patella
• chondromalacia patellae
• knee joint effusion
• Patella alta may also occur as a result of spastic
cerebral palsy .

70. • Caton Deschamps
index =
A/B. Normal mean
= 1.
Ratio greater than
1.3 is highly
suggestive of
patella alta.

71. • Patellar tendon rupture resulting in patella
alta.

72. Patella Baja
• Patella baja (or patella infera) is an abnormally low lying patella, which is
associated with restricted range of motion, crepitations and retropatellar
pain. If long standing extensor dysfunction may ensue with significant
morbidity. It is seen in a variety of clinical scenarios including 1:
• quadriceps dysfunction:
– poliomyelitis
– tourniquet paralysis
• bony or ligamentous trauma:
– fractures
– osteotomies
– tibial tubercle transplant
– ACL repair
– total knee replacement: seen in 25% of patients 1
• achondroplasia: usually asymptomatic

73. Radiographic features
• A number of methods for determining patella height have been
devised:
• Insall-Salvati ratio: according to the relative height of the patella
and length of the patellar tendon. It is assessed on lateral
radiographs or sagittal cross-sectional imaging.
• Blackburne-Peel ratio: ratio of vertical distance between tibial
plateau and patellar articular surface and length of the patellar
articular surface.
• Norman, Egund and Ekelund method
• Caton-Linclau method
• Blumensaat's technique
• It is important in the setting of previous surgery to ensure that the
patella has not been resected, as change in patellar morphology will
clearly affect the ratio .

75. • Height from line to
inferior edge of the
patellar articular
surface (PAS) :
Length of PAS =
23.2:32.5= 0,71

76. • Patella Baja

77. Ankle Dislocation
• Four types of dislocations are seen around the ankle
joint: posterior, anterior, lateral, and superior:
• Posterior
• A posterior dislocation in the most common type of
ankle dislocation. The talus moves in a posterior
direction in relation to the distal tibia as force drives
the foot backward. The wider anterior talus wedges
back, resulting in forced widening of the joint.
• This must be accompanied by either a disruption if the
tibiofibular syndesmosis or a fracture if the lateral
malleolus. This occurs most commonly when the ankle
is plantar flexed.

78. • Figure 1 X-ray showing posteromedial
dislocation of the right ankle without fracture
in patient 1.

79. • Figure 5 X-ray of posterior dislocation of the
left ankle of patient 3.

80. • Posterior dislocation of the talus with respect to the tibia (red arrows) is the most
common type of ankle dislocation. Dislocation may be associated with a distal
fibula fracture (blue arrow). Pure ankle dislocations must be distinguished from
subtalar (foot) dislocations because reduction techniques for the two differ.
Neurovascular compromise is an indication for immediate reduction without
waiting for radiographs. However, clinicians should be aware that attempts to
reduce a subtalar dislocation using the ankle reduction technique will be
unsuccessful and may further damage the articular cartilage. Image courtesy of
Wikimedia Commons.

81. Ankle Dislocation
• Anterior
• Anterior dislocations result from the foot
being forced anteriorly at the ankle joint.
• Typically, this occurs with the foot fixed and a
posterior force applied to the tibia or with
forced dorsiflexion.

82. Ankle Dislocation
Lateral
• These dislocations result from forced
inversion, eversion, or external or internal
rotation of the ankle.
• They are associated uniformly with fractures
of either or both the malleoli or the distal
fibula.

83. • Figure 2. Lateral Ankle Fracture Dislocation -
failure of the lateral malleolus with lateral
dislocation of the talus. ORIF reduces the
fractures, restoring the talus in the mortise,
with its stable malleolar buttresses.

84. Ankle Dislocation
Superior
• Diastasis occurs when a force drives the talus
upward into the mortise. These dislocations
usually are the result of a fall from a height.
• In such cases, the patient should be evaluated
carefully for concomitant spine injury and
fracture of the calcaneus.

85. • Figure 3. Superior
Ankle Fracture
Dislocation - high-
energy axial force
pushes the talus into
the mortise,
disrupting the
syndesmosis and
allowing for talar
dislocation.

86. Lisfranc injury
• The 'Lisfranc' ligament stabilizes the mid-
forefoot junction. Loss of alignment of the 2nd
metatarsal base with the intermediate
cuneiform indicates injury to this important
ligament.
• Every post-traumatic foot X-ray must be
checked for loss of alignment at the midfoot-
forefoot junction (tarsometatarsal joints).

87. • Second metatarsal Lisfranc injury - DP
• displaced from the intermediate cuneiform
• No fracture is visible but this is a severe injury which is
debilitating if untreated
• NOTE: Lisfranc ligament injury can be subtle and does
not always result in displacement - If there is a clinically
suspected ligament injury then clinical and radiological
follow-up must be arranged

88. Chopart Fracture
• Fracture dislocation through midtarsal/
chopart (calcaneocuboid-talonavicular) joint.
• There are frequently associated fractures of
the calcaneus, cuboid and navicular

89. • Chopart's fracture
dislocation. Black arrow
points to talus which is
dislocated from navicular
(yellow arrow) at
talonavicular joint.
Calcaneus (blue arrow) is
dislocated from the cuboid
(red arrow), which is also
fractured. The dislocation is
at the calcaneocuboid joint.
This is an uncommon
dislocation.
The forefoot is usually
displaced medially rather
than laterally as in this case.

90. Thank you
• Special Thanx To Radiology Master Class.