Hip and Pelvis

Question 1

The majority of females have what kind of pelvis?

Answer 1

gynaecoid

Question 2

What type of pelvis do males have?

Answer 2

android

Question 3

What are the routine projections of the Hip?

Answer 3

AP and Lateral

Question 4

What are the routine projections of the pelvis?

Answer 4

AP

Question 5

What are the clinical indications for the hip?

Answer 5

A hip x-ray is indicated if there has been trauma, if there is hip pain or abnormal gait, the patient cannot bear weight on the affected side, arthropathy (joint disease) of if the patient has knee pain – hip conditions can often present as knee pain.

Question 6

What are the clinical indications for the pelvis?

Answer 6

Pelvis x-rays are indicated for a number of reasons: blunt trauma; generalised hip pain, arthropathy (a joint disease); post operative follow up after a total hip replacement; paget’s disease or if the patient has had a fall.

Question 7

How is the patient positioned in an AP pelvis X-ray?

Answer 7

The patient is supine and the lower limbs are internally rotated 15-25°from the hip – this should not be attempted if a fracture is suspected! This Internal rotation demonstrates an AP view of the proximal femur.

Question 8

What does an AP pelvis X-ray allow us to view?

Answer 8

TheAP pelvis viewis part of the routinepelvic series which examines the iliac crest, sacrum, proximal femur, pubis, ischium and the great pelvic ring.
The AP Pelvis allows us to assess for joint dislocations and fractures when there has been trauma as well as bone lesions and degenerative diseases.

Question 9

What constitutes an adequate image for AP Pelvis?

Answer 9

An adequate image should demonstrate the whole of the bony pelvis from superior of the iliac crest to the proximal shaft of the femur; the obturator foramina appear symmetrical; the iliac wings have an equal concavity; and the greater trochanters of the proximal femur are in profile (from the side).

Question 10

What is the patient’s position for an AP Hip X-ray?

Answer 10

The patient’s position is the same as the AP pelvis – they are supine and the hip is internally rotated 15 to 25 degrees, and the collimation (size of the beam) is adjusted to just image one side/one hip.

Question 11

Why would you take an AP Hip X-ray?

Answer 11

Potential fractures,dislocations, bone lesions or degenerative diseases to the hip joint, post-operative examinations evaluating the placement of existing orthopaedic devices

Question 12

What does an AP Hip X-ray view assess?

Answer 12

The AP hip assesses one hip – unilateral – and allows us to get a closer look at the hip joint and the proximal femur. If both hips are to be assessed at the same time then an AP pelvis would be more favourable then the unilateral image.

Question 13

What constitutes an adequate AP Hip X-ray?

Answer 13

An adequate image should demonstrate the whole of the hip and proximal femur with the long axis of the femur running parallel to the long axis of the image. The greater trochanter should be seen in profile which demonstrates adequate internal rotation of the lower limb.

Question 14

When would you not use a lateral hip x-ray?

Answer 14

When the patient has had trauma or suspected fracture.

Question 15

How do you conduct a lateral hip x-ray?

Answer 15

The lateral hip involves rolling the patient onto the side of interest with 90 degrees hip flexion, meaning it is not suitable for trauma situations. If there has been trauma, you would perform a horizontal beam lateral hip which involves moving the x-ry beam rather than moving the patient.
For the lateral hip, again it is a unilateral projection – demonstrating one side/hip.

Question 16

What constitutes an adequate image of a lateral hip x-ray?

Answer 16

An adequate image will demonstrate the pelvis from ASIS to the proximal shaft of the femur, Closed obturator foramina due to the superimposition of the pubic rami, the Greater and lesser trochanters of the proximal femur are in profile, the Proximal one-third of the femur is visible and there may be some foreshortening of the femoral neck due to superimposition.

Question 17

What are the additional projections of the hip?

Answer 17

Frog leg lateral

Question 18

What are the additional projections of the pelvis?

Answer 18

Judet View
Inlet/Outlet

Question 19

Why would you take a Judet view of the pelvis?

Answer 19

If there is suspicion of acetabular fracture

Question 20

What is the 1st projection for a Judet View Pelvis X-ray?

Answer 20

Iliac oblique
assessment of theposterior columnand anterior wall of the acetabulum

Question 21

What is the 2nd projection for a Judet View Pelvis X-ray?

Answer 21

Obturator oblique
assessment of theanterior column and posterior wall of theacetabulum

Question 22

In an Iliac Oblique Judet view of the pelvis, how is the patient positioned?

Answer 22

patient is supine
the unaffected side is rotated roughly 45°anterior, generally aided with a 45° sponge
it is advisable the patient is central on the table and at no risk of over rolling
(lie on the affected side)

Question 23

In an Obturator Oblique Judet view of the pelvis, how is the patient positioned?

Answer 23

patient is supine
the affected side is rotated roughly 45° anterior, generally aided with a 45° sponge
ensure the patient is central on the table and at no risk of over rolling
(lie on unaffected side)

Question 24

How is a patient positioned in an Outlet Pelvis X-ray?

Answer 24

The central ray is angled 20-35° cephalic for males and 30-45° for females
Assessment of cephalic/caudal translation andsuperior migrationof the hemipelvis following trauma and suspected fractures or lesions of the pubic rami

Question 25

How is a patient positioned in an Inlet Pelvis X-ray?

Answer 25

The central ray is angled 25-40° caudal to be perpendicular to the plane of the pelvic inlet Assessment of any suspected narrowing or widening of that rim and anterior-posterior displacement of pubic rami fractures

Question 26

What should the anatomy look like in an AP Outlet View of the pelvis?

Answer 26

the pubic symphysis should be central to the image with little to no patient rotation. there is a clear demonstration of both the superior and inferior pubic ramus with little to no foreshortening

Question 27

What should the anatomy look like in an AP Inlet view of the pelvis?

Answer 27

The entirety of the bony pelvic rim is central to the image without superimposition The iliac wings are evident on the superior portion of the image, the inferior and superior pubic rami are superimposed on the inferior portion

Question 28

What is a Frog Leg Lateral Hip X-ray?

Answer 28

Bilateral examination allows for better visualisation of the hip joints and femoral neck. It is almost exclusively used in the paediatric population slipped capital femoral epiphysis Perthes disease

Question 29

How do you assess for adequacy of the Frog Leg Lateral Hip X-ray?

Answer 29

the entirety of the bony pelvis is imaged from superior of the iliac crest to the proximal shaft of the femur the obturator foramina appear equal the iliac wings have an equal concavity greater trochanters of the proximal femur are in profile

Question 30

What is Shenton's line of measurement for the Hip?

Answer 30

Curved line drawn along: Inferior border of the superior pubic ramus (superior border of obturator foramen) Inferomedial border of the neck of femur Line should be continuous and smooth Interruption of a Shenton Line can indicate: DDH – Developmental Dysplasia of the Hip Fractured Neck of Femur

Question 31

What are pelvic rings?

Answer 31

Trace the main pelvic ring and two obturator foramina if a ring is disrupted, think fracture... then look for a second one

Question 32

What are sacral arcuate lines?

Answer 32

Lines should be smooth and symmetrical. Disruption of the arcuate lines can indicate fracture of the sacrum

Question 33

What is Hilgenreiner’s Line?

Answer 33

Line drawn horizontally through the inferior aspect of both triradiate cartilages It should be horizontal Femoral head ossification should be inferior to this line Used in the diagnosis of developmental dysplasia of the hip (DDH)

Question 34

What is perkin's line?

Answer 34

Line drawn perpendicular to Hilgenreiner line, intersecting the lateral most aspect of the acetabular roof If the nucleus of the femoral head is not visible (not ossified yet) the femoral metaphysis should be used femoral head ossification should be medial to this line Lateral displacement of the femoral head = developmental dysplasia of the hip (DDH).

Question 35

What is Hilgenreiner’s and Perkin’s Line?

Answer 35

The upper femoral epiphysis should be seen in the inferomedial quadrant: it should lie below Hilgenreiner’s line, and medial to Perkin’s line

Question 36

What is the pubic Symphysis width?

Answer 36

Pubic Symphysis = Midline cartilaginous joint that unites both pubic bodies Females have a greater thickness of the fibrocartilaginous disc: allowing more mobility of the pelvic bones  childbirth Widening of this joint space = Pubic Symphysis Diastasis, 10mm or greater is diagnostic 3 years ~ 10mm 20 year ~ 6mm 50 years ~3mm

Question 37

What is the Femoroacetabular Joint Space?

Answer 37

Superior: 3-6 mm Medial: 4-13 mm Axial: 3-7 mm Loss of joint space is often an indicator of degeneration/osteo-arthritis

Question 38

What is Kohler’s Teardrop Distance?

Answer 38

lateral aspect of the pelvic teardrop and the medial aspect of the femoral head Waldenström sign = increased distance between the pelvic teardrop and the femoral head >11 mm total distance or >2 mm difference compared to contra-lateral hip Hip joint effusion or hip dysplasia

Question 39

What is Kohler’s Line – ilioischial line?

Answer 39

Evaluation of posterior column of the pelvis. AP Pelvis radiograph Outer border of the obturator foramen to the medial border of the iliac wing It should pass through the acetabular teardrop Femoral head should not interfere with this line Abnormalities rheumatoid/degenerative arthritis, Paget’s disease, osteogenesis imperfecta and other bone softening conditions

Question 40

What is skinner's line?

Answer 40

Relationship of the fovea capitis to the trochanteric line AP Pelvis Longitudinal femoral shaft axis (A). Perpendicular line tangential to the tip of the greater trochanter (B) Perpendicular line should pass through or below the fovea capitis Hip joint abnormality present if line is found above the fovea capitis; suspect fracture or bone-softening conditions

Question 41

What is Iliofemoral Line?

Answer 41

AP pelvis  A curvilinear line, along the outer surface of the ilium, through the superior acetabular rim and the femoral neck bilaterally symmetrical Asymmetry congenital dysplasia,  slipped femoral capital epiphysis (SCFE), Dislocation fracture

Question 42

What is Acetabular Angle/Index?

Answer 42

evaluating potential developmental dysplasia of the hip (DDH) Angle formed by Hilgenreiner’s line and Perkin’s line. ADULT: tridate cartilage is fused – use inferior margin of pelvic teardrop.  horizontal line shifts inferiorly = angle changes CHILDREN Angle < 28° at birth Angle should become progressively shallower with age > 1 year old : angle should measure less than 22° ADULTS Normal range = 33°-38° Angles >47°  acetabular dysplasia 39°-46° - indeterminate (not exactly known) Conditions associated with increased acetabular angles include: Neuromuscular disorders Developmental dysplasia of the hip (DDH) Conditions associated with decreased acetabular angles: Down syndrome Achondroplasia

Question 43

What is the femoral angle?

Answer 43

angle formed between the neck of the femur and its shaft Normal range: 120-135 degrees <120° Coxa Vara Deformity of the hip where the formed between the head and neck of the femur and its shaft is decreased Congenital or acquired The common mechanism in congenital cases is a failure of medial growth of the epiphyseal plate >135o Coxa Valga Deformity of the hip where there is an increased angle between the femoral neck and femoral shaft Bilateral causes include:- neuromuscular disorders, e.g. cerebral palsy skeletal dysplasia's, e.g. Turner syndrome, mucopolysaccharidoses Unilateral causes include:trauma causing growth plate arrest

Question 44

What is the Subpubic Angle?

Answer 44

angle that is formed just below the pubic symphysis

Question 45

What is Os Acetabuli?

Answer 45

Accessory ossicle - unfused secondary centres of the acetabulum acetabular rim may be bilateral and partially fused to the acetabulum What causes them? Ununited secondary ossification centre Incomplete healing of acetabular rim # Ossifications within the acetabular labrum How are they diagnosed? X-ray : rounded in shape, concave lateral border, convex medial border, acetabular rim Clinical significance: Normally seen in children  typically fuse in mid-to-late teens = uncommonly seen in adults. Mostly asymptomatic Possible acetabular impingement

Question 46

What is Paraglenoid Sulcus?

Answer 46

AKA: pre-auricular sulcus Variable groove in the ilium adjacent to the inferior end of the sacroiliac joint What causes them? Resorption at the insertion of the anterior sacroiliac ligament in response to stress How are they diagnosed? X-ray : Bilateral symmetric indentations of the ossa ilia, lateral to the lower borders of the sacroiliac joints Clinical significance: associated with Osteitis Condensans Ilii

Question 47

What is Synovial Herniation Pits?

Answer 47

AKA Pitt’s pits Anterosuperior aspect of the femoral neck, distal to the articular surface.  Herniation of synovium or soft tissues into the bone through a cortical defect What causes them? Exact aetiology is debatable femoroacetabular impingement   around 30% of patients with this condition are found to have a pit How are they diagnosed? X-ray : oval or round lucency in the anterosuperior aspect of the femoral neck Diameter = 5 mm(Range 3-15 mm) Clinical significance: “Do Not Touch” lesion

Question 48

What are Bilateral Iliac Horns (Fong’s Prongs)?

Answer 48

bony protuberances (“iliac horns.) arising bilaterally from the posterior aspects of the iliac bones What causes them? present in ~80% of patients with Nail-Patella Syndrome How are they diagnosed? X-ray : bilateral triangular shaped bony protuberance on the iliac fossa, lateral to the SI joint. Clinical significance: Other diagnostic radiographic findings associated with Nail-Patella Syndrome: fragmented/absent/hypoplastic patellae with a tendency for recurrent patellar dislocation hypoplasia of the radial head and/or capitellum leading to subluxation or dislocation dorsally flared iliac crests with protuberant anterior iliac spines

Question 49

What is Ischiopubic Synchondrosis?

Answer 49

the junction between the inferior ischial and pubic rami  principally composed of hyaline cartilage. temporary joint, occurring in childhood prior to fusion of the ischial and pubic bones

Question 50

What is Ischiopubic Synchondrosis Asymmetry?

Answer 50

Aka van Neck-Odelberg disease enlargement of one of the ischiopubic synchondroses What causes them? Mechanical stress – non-dominant leg How are they diagnosed? X-ray : Asymmetric enlargement and lucency of the synchondrosis, often simulating a lytic lesion Clinical significance: a common and usually asymptomatic finding. Symptomatic cases = groin or buttock pain in ambulatory, pre-pubertal children Resolves with skeletal maturation

Question 51

What are Phleboliths?

Answer 51

"vein stones", What causes them? calcification within venous structures m/c >40yrs M=F Uncertain – congenital or non-congenital How are they diagnosed? X-ray : focal calcifications, often with radiolucent centres, comet tail sign - (tail of soft tissue extending from a calcification, representing the collapsed/scarred/thrombosed parent vein) Clinical significance: may mimic ureteric calculi Seen in venous malformations. Can be associated with Maffucci Syndrome. 

Question 52

What is normal structures that simulates pathology - Kohler's teardrop?

Answer 52

Normal radio-dense projection that resembles a teardrop What causes it? Results from the end-on projection of a bony ridge running along the floor of the acetabular fossa: Lateral = inferior-anterior acetabular fossa Medially = anterior surface iliac bone X-ray : radio-opaque teardrop supero-lateral to the obturator foramen Clinical significance: A feature of Paget disease of the pelvis = disappearance of the pelvic teardrop. The ilioischial line intersects the teardrop In adults, it may be used as a marker for measurement of the acetabular angle and Köhler teardrop distance

Question 53

What is normal structures that simulates pathology - prominent Ischial Spines?

Answer 53

Ischial Spine Sign Dx of acetabular retroversion What causes them? rotation of the entire acetabular complex X-ray : triangular projection of the ischial spine is visible medially to the pelvic inlet or iliopectineal line Clinical significance: Predisposes pt. to femoroacetabular impingement

Question 54

What are normal structures that simulates pathology - Kohler's teardrop?

Answer 54

Normal radio-dense projection that resembles a teardrop What causes it? Results from the end-on projection of a bony ridge running along the floor of the acetabular fossa: Lateral = inferior-anterior acetabular fossa Medially = anterior surface iliac bone X-ray : radio-opaque teardrop supero-lateral to the obturator foramen Clinical significance: A feature of Paget disease of the pelvis = disappearance of the pelvic teardrop. The ilioischial line intersects the teardrop In adults, it may be used as a marker for measurement of the acetabular angle and Köhler teardrop distance

Question 55

What are normal structures that simulates pathology - Vascular Grooves?

Answer 55

Vascular/nutrient channel is a small tunnel through the cortex of a long bone containing a nutrient artery which supplies the bone Ilium = Flat bone – appears as groove How are they diagnosed? X-ray : In ilium, seen as “Y” or “V” shaped grooves in the main bodies of the ilia In the femur, seen pointed away from knee Lucent lines with sclerotic borders Clinical significance: Can be mistaken for fractures

Question 56

What are normal structures that simulates pathology - Ward's triangle?

Answer 56

A radiolucent area between principal/primary compressive, secondary compressive and primary tensile trabeculae in the neck of femur How are they diagnosed? X-ray : radiolucent triangle on the neck of femur enclosed by white trabecular lines. Clinical significance: A reduction in the trabeculae lines = Ward’s triangle looks bigger and less distinct  osteopenia

Question 57

What are normal structures that simulates pathology - Risser's Sign/Classification?

Answer 57

Used to grade skeletal maturity based on the level of ossification and fusion of the iliac crest apophyses Stage 0 and 5 can appear similar Stage 0  open growth plates in most long bones Stage 5  NO open growth plates in long bones (stopped growing) X-ray : stage 0: no ossification centre at the level of iliac crest apophysis stage 1: apophysis under 25% of the iliac crest stage 2: apophysis over 25-50% of the iliac crest stage 3: apophysis over 50-75% of the iliac crest stage 4: apophysis over >75% of the iliac crest stage 5: complete ossification and fusion of the iliac crest apophysis Clinical significance: Mistaken for fracture Age the radiograph

Question 58

What are normal structures that simulates pathology - Triradiate Cartilage?

Answer 58

Y- shaped epiphyseal plate between the ischium, ilium, and pubis in a skeletally immature skeleton.  Complete fusion: M ~ 15-16yrs | F ~ 13-14yrs X-ray : radiolucent line/gap between the ilium and pubis extending from the acetabulum to the pelvic inlet bilaterally Clinical significance: Evaluation for developmental dysplasia of the hip  landmark for Hilgenreiner’s line and Perkin’s line

Question 59

What are normal structures that simulates pathology - Accessory Superior Acetabular Notch?

Answer 59

Normal anatomical variant on the superior acetabular roof X-ray : Small lucencies in the roof of the acetabulums bilaterally (this image) Clinical significance: Do not confuse with fracture!

Question 60

What are normal structures that simulates pathology - Fovea Capitis?

Answer 60

A small, oval-shaped dimple on the femoral head What causes it? Attachment site of ligamentum teres X-ray : small half-oval shaped indentation on the femoral head Clinical significance: appears as an erosion or osseous destructive process

Question 61

What are normal structures that simulates pathology - Acetabular Roof?

Answer 61

Superior aspect of the acetabulum – main weight-bearing region What causes them? Normal or increased stress on the superior acetabulum How are they diagnosed? X-ray : sclerotic appearance of the superior acetabulum Clinical significance: Mistaken for degenerative sclerosis