Week 5: Infant Hip
septic arthritis
a bacterial infection that can cause permanent damage to the hip joint if not treated quickly
hip dysplasia
a congenital or developmental deformation or misalignment of the hip joint; more common in females, infants who have family history, or who have had a breech presentation in utero
Slipped capital femoral epiphysis
a hip condition that occurs in teens and pre-teens who are still growing -the femoral ball slips off the neck in a backwards direction -causes pain, stiffness and instability in the affected hip (more common in males) -fracture -arthritis
liagementum teres
a ligament located deep in the hip joint. It connects the ball (femoral head) to the socket (acetabulum) and provides blood supply to the femoral head; also important for stability
Where does the neonatal hip develop from?
mesoderm
adduction
moving sideways inward
Which is the most anterior of the bones?
pubis
transverse/neutral view position
-leg neutral position 15%-20% flexion -transducer horizontally into the acetabulum from the lateral aspect of the hip
fascia lata
a sheet or band of fibrous sheath that forms a complete cover for the thigh and has an opening in front just below the inguinal ligament
femoral triangle
a triangular space in the anterior aspect of the upper thigh bounded by: -inguinal ligament -adductor longus -sartorius -floor formed by iliopsoas -medially by pectineus muscle -contains femoral vein, artery and nerve
Galeazzi Sign
abnormal hip examination where the knee is lower in position of the affected side when the patient is supine and the knees are flexed
What pathology is seen in this ultrasound image?
abnormal vs normal synovial space in the hip
A dislocated hip has no contact with or coverage by the _____.
acetabulum
extension
bending backwards
flexion
bending forward
What pathology is seen in this ultrasound image? Label the structures.
coronal C: capsule G: gluteus muscle GT: greater trochanter H: cartilaginous femoral head IL: ilium IS: ischium L: labrum Tr: triradiate cartilage
What view is seen in this ultrasound image?
coronal (with flexed hip)
If you encounter a hip that is completely dislocated, why shouldn't you attempt to stress?
could cause damage to the soft tissue
What pathology is seen in this ultrasound image?
dislocated hip
What pathology is seen in this ultrasound image?
femoral head
When does the neonatal hip ossify and where does it begin?
femoral head between 2-8 months; begins from the center to the periphery; ossifies earlier in females
bony pelvis
fusion of ilium, ischium, pubis
What pathology is seen in this ultrasound image?
hip dysplasia
What pathology is seen in this ultrasound image?
hip effusion
What pathology is seen in this ultrasound image?
hip subluxation (no stress vs. stress)
osteomyelitis
inflammation of the bone
Which view, position, and hip is seen in this ultrasound image?
left hip, coronal, flexion/abduction
What view is seen in this ultrasound image?
transverse
What pathology is seen in this ultrasound image? Label the structures.
transverse flexion G: gluteus muscle H: cartilaginous femoral head IS: ischium L: labrum FS: femoral shaft M: femoral metphysis
True or False: For hip effusion, ultrasound only assists determining presence of fluid, but not the etiology.
true
What graf type is seen in this ultrasound image?
type 1
What graf type is seen in this ultrasound image?
type 2
What graf type is seen in this ultrasound image?
type 3
What graf type is seen in this ultrasound image?
type 4
What will help the clinician decide if hip aspiration is necessary?
ultrasound alone cannot distinguish between the two but the presence of fluid in the joint along with lab work will help the clinician decide if hip aspiration is necessary
What does normal hip placement require?
both heads to be seated normally and congruently within the acetabulum
What happens if hip placement is not in normal position?
both sides will develop abnormally
What was developmental displacement of the hip formerly known as?
congenital hip dislocation
What are the hip abductor muscles?
gluteal muscles: gluteal maximus, gluteal medius, gluteal minimus
_____ uses a series of lines and angle measurements to evaluate the morphology of the acetabulum.
graf
What transducer and at which frequencies are used when performing an ultrasound on the neonatal hip?
high frequency linear array transducer -premature: 12 MHz -0 - 3 months of age: 7.5 MHZ -3 - 7 months: 5.0 MHz• -> 7 months: 3 MHz (rarely)
What can severe abnormal hip placement cases cause?
impaired function and degenerative joint disease (diagnosis should be made early and treatment instituted promptly)
Why is radiography more reliable for scanning the hip after 6 months of age?
it increases bony ossification
What ligament contains an artery to supply the femoral head (in the younger child)?
ligamentum teres
How many hip dislocations cases are made by ultrasound?
may be as high as 40-60 cases per 1000 births
abduction
moving sideways outward; the gluteus medius and minimus muscles opens the limbs
When is graf type 2 normal?
normal if newborn, up to 3 months of age; indicates slowed development, alpha angle 44-60; head covered 50% and acetabulum is rounded
hip effusion
occurs with synovial fluid builds up in the capsule
What is the hip joint reinforced by?
outside ligaments and muscles: femoral head, iliofemoral ligament, triangular ligament
coronal view position with hip flexion at 90 degrees
push and pull maneuver: -normal hip will never show the femoral head slipping over the posterior lip of the acetabulum -with instability, this can be seen as the femur pushed -when pulled the head disappears from the plane barlow maneuver: -gently adduct and push against the knee -with subluxation or dislocation, the head will migrate laterally or posteriorly -echogenic soft tissue will be seen between the femoral head the acetabulum (Pulvinar)
proximal focal femoral deficiency (PFFD)
rare non-hereditary birth defect that affects the pelvic, specifically the hip bone and proximal femur; commonly associated with an absence or shortening of the leg bone and absence of kneecap
inguinal ligament
serves to contain the soft tissue as they courses anteriorly from the trunk to the lower extremity; marks the superior and inferior border of the femoral triangle
The _____ ________ are imaging counter parts of the Barlow and Ortolani maneuvers.
stress maneuvers
______ is when the head is either in contact with part of the acetabulum or is displaced, but partly covered.
subluxation
graf type 3
subluxation with a shallow acetabulum α < 50 degrees; acetabular rim rounded
Perthes disease
temporary loss of blood supply to the hip -the area becomes intensely inflamed and irritated -usually seen in children between 4-10 years of age -5 times more common in boys than in girls
hip dysplasia
the Alpha angle is less than 60°, indicating a shallow acetabulum; the femoral head has less than 50% coverage without stress
medial rotators
the anterior fiber of the gluteal medius and minimus
Where does the gluteal region extend from?
the iliac crest to the gluteal fold and from the midline over sacrum to the greater trochanter of femur
lateral rotators
the small muscles at the back of the joint-piriformis, obturator internus and quadratus femoris, with assistance from the gluteus maximus
What is the most important function of the hip abductor muscles?
to prevent abduction and keep the pelvis level during walking
What is the most important function of the gluteus medius and minimus?
to prevent adduction which is the function they perform during walking
Why is ultrasound used for scanning the infant hip?
ultrasound evaluates the degree to which the femoral head is covered by the labrum as well as the position of the femoral head in the acetabulum at rest and during motions and stress
Is the neonatal hip compromised?
yes (femoral head, acetabulum)
graf type 2
-50-60 degrees -reflects a physiologic immaturity in infants less than 3 months old -follow-up would be required but no treatment -if an infant is greater than 3 months old, treatment would be necessary -normal if newborn, up to 3 months of age; indicates slowed development, alpha angle 44-60; head covered 50% and acetabulum is rounded
graf technique (static)
-acquire image in the coronal plane at the mid acetabular level from the lateral aspect of the neutral position -images included: femoral head, acetabulum, labrum, iliac bone as it meets the triradiate cartilage -measures the alpha or beta Graf angles
What are the adductor muscles and where do they each originate?
-adductor longus: originates at the pubic bone near symphysis -adductor magnus: originates at the ischial tuberosity -adductor gracilis: originates at the lower edge of the symphysis
lateral rotation
-backward movement of the trochanter -lateral rotators are the small muscles at the back of the joint-piriformis, obturator internus and quadratus femoris, with assistance from the gluteus maximus
What does the neonatal hip consist of?
-bony pelvis (Girdle) -superior portions of the femur -hip joint: acetabulum, acetabulum labrum, supporting ligaments and muscles
What are the clinical symptoms of hip dislocation?
-careful physical examination remains the universal screening and therefore is critical to the diagnosis -asymmetric skin folds of the thigh -one knee that appears to be lower than the other when knees and hips are flexed -hip click -newborns with slight positive physical exam and a risk factor for DDH should be examined with sonography after this period to reduce false-positive result -newborns with a grossly positive physical examination result or dislocation for DDH are often seen earlier
sonographic evaluation of the neonatal hip
-clearly visible structures -femoral head -cartilaginous acetabular rim• -labrum -characteristics assessed by ultrasound -femoral head: size, shape, position, motion
labrum
-composed of hyaline cartilage that surrounds the acetabulum and forms an extension of the acetabular roof -narrows the acetabulum and increases depth function in stabilizing and supporting the femoral head articulation with the acetabulum
developmental displacement of the hip (DDH)
-congenital malformation of the hip joint that either results in dislocation of the femoral head from the acetabulum or underdevelopment of the acetabulum -believed to cover a spectrum of pathologies that usually develops after birth -is now used to encompass a spectrum of pathologies: subluxation, dysplastic, dislocation, dislocated hips -also called: developmental dysplasia of the Hip (DDH)
sonographic protocol when scanning neonatal hip
-coronal and transverse view in neutral and flexed positions -stress to the infant hip by either push or pull or the Barlow Maneuver -make sure baby is fed and warm or has a pacifier -it is ok to allow family member -can be performed with one or two personnel
What are indications for ultrasound of the neonatal hip?
-developmental displacement of the hip (DDH): does not fit firmly into the acetabulum -septic arthritis: inflammatory process in the acetabulum/orthopedic emergency -joint effusion: fluid accumulation -proximal focal femoral deficiency: rare non-hereditary birth defect that affects the pelvic, specifically the hip bone and proximal femur; commonly associated with an absence or shortening of the leg bone and absence of kneecap
Describe the incidences and demographic evaluation of hip dislocation.
-difficult to define -no gold standard test at this point -estimated between 1.5 to 20 cases per 1000 births -left hip affected 64% of time -African Americans 0.06 per 1000 -Native Americans 76.1 per thousand
graf type 4 (DDH bilateral)
-dislocation that lacks contact between the femoral head and acetabulum -α < 43 deg or immeasurable with significant dysplasia (with or without changes of the labrum -femoral head is completely displaced. -acetabular rim is flattened -urgent orthopedic referral
transverse flexion view
-echogenic shaft of the femur is seen anteriorly to the hypoechoic femoral head -acetabulum is seen posterior to the femoral head -a U-shaped configuration in seen; the metaphysis and ischium surround the femoral head -the push pull technique is applied for subluxation and dislocation with the same findings as listed before -barlow test: normal remains in place, subluxation femoral head displaces laterally, dislocation femoral head pops out with not contact remaining with the acetabulum
medial rotation
-forward movement of the trochanter -medial rotators are the anterior fiber of the gluteal medius and minimus
What are the supporting muscles, tendons, and ligaments?
-iliopsoas tendon -iliofemoral ligament -inguinal ligament -ligament teres (head of the femur) -iliacus muscle -psoas muscle -gluteus maximus muscle -gluteus minimus muscle -gluteal medius muscle -muscle extensor/anterior groups
sonographic appearance at coronal view with hip flexed position
-ilium appears as a straight line parallel to the transducer -femoral head is seen resting in the acetabulum -echogenic cartilage tip of the labrum is seen -normal hips should have a "ball on a spoon" appearance: femoral head is the ball, acetabulum is the curve in the spoon, ilium is the handle of the spoon -with subluxation, the head will migrate superiorly or laterally, but remain in the joint -with dislocation, the femoral head can be seen out of the joint
coronal view with flexed hip position
-infant in supine position or lateral decubitus position from the lateral aspect of the hip joint -transducer is placed parallel to the lateral aspect of the infant's hip -images are taken with the neonate's leg flexed
What are the causes of hip dislocation?
-laxity (loose, elastic joint capsule) -genetic (family history) -mechanical (Swaddled too tight) -physiological (breech position) -believed to be caused by hormones (theory): estrogen increases muscle laxity late in pregnancy (aids in childbirth) more common for females; progesterone increases the collagen content in the joint capsule facilitating hip dislocation -hip instability may resolve after 4-6 weeks, due to waning maternal hormones
triradiate cartilage (Y shape)
-lies posterior to the femoral head -useful sonographic landmark appears hypoechoic (not ossified at birth) -fused completely by 20-25 years of age
What is each line in the graf angles?
-line 1: baseline, drawn along the ilium, extending through the head of the femur -line 2: provides the alpha angle drawn from the bony edge of the acetabulum at the triradiate cartilage to the lowest point of the ilium -line 3: provides the beta angle, drawn form the ilium along the labrum
acetabulum labrum
-located in acetabular rim -extends over the superolateral aspect of femoral head -increases the surface strength of hip joint
acetabulum
-located on the lateral surface of hip bone -receives the head of femur
alpha angle (α)
-measures the acetabular depth -the alpha angle reflects changes in the osseous portion of the acetabulum which occur gradually -normally greater than 60%
general sonographic appearance of the neonatal hip
-mid portion of the acetabulum is seen -ilium junction and triradiate cartilage should be seen -tip of the echogenic labrum should also be identified -a normal hypoechoic femoral head is seen resting against the acetabulum -with subluxation, the hip will migrate superiorly or laterally, but remain in the joint
pubis
-most anterior portion of the hip bone -composed of three parts: body, superior rami, inferior rami
transient synovitis
-most common hip effusion in children 3-10 years of age -more prevalent in males -believed to be caused by an inflammatory response to viral infection: present with localized pain, unable to apply weight, limited mobility, capsular thickness of greater than 5mm, removal of fluid brings relief
iliofemoral ligament
-most important ligament -passes from the anterior inferior iliac spine to the end of the intertrochanteric line -strongest ligament in the body -important for standing and maintaining correct upright balance -functions: flexion, extension, abduction, adduction, medial rotation, lateral rotation
What occurs within unrecognized hip dislocation?
-muscles tighten -limit movement: causes the acetabulum to become dysplastic, because it lacks the stimulation of the femoral head -ligaments stretch -fibrofatty tissue occupies the acetabulum making it impossible for the femoral head to return to acetabulum
graf type 1
-normal angle= α >60 %, β < 55 % -covers femoral head >50% -acetabular rim is angular -labrum in normal position -alpha angle >60 degrees
sonographic appearance at transverse/neutral view position
-normal: hypoechoic femoral head is seen against the acetabulum over the triradiate cartilage -resembles a flower: femoral head is the flower; echoes from the posterior ischium and anterior pubis create the leaf appearance; the stem is created by the shadow of the triradiate cartilage -subluxation and dislocation, soft tissue echoes are seen between the femoral head and acetabulum -subluxation: femoral head moves posterior and/or laterally -dislocation: femoral head moves out of the acetabulum laterally, posterior and superior and rest against the boney ilium
Ortolani Maneuver
-patient in supine position -examiner hand is placed around the hip with fingers over the femoral head -the examiners middle finger lies over the greater trochanter and the thumb is over the lesser trochanter -hip is flexed at 90% and the thigh is abducted -normal movement should be smooth -abnormal movement in cases of DDH, a clunk is appreciated as the femoral head returns into the acetabulum -dislocated hip may produce a palpable or audible click as the hip relocated into the acetabulum
Barlow Maneuver
-patient in supine position with hip flex 90% and adducted -downward and outward pressure is applied -if the hip can be dislocated , the examiner will feel the femoral head move out of the acetabulum with his or her fingers
DDH treatment
-pavlik harness to flex, abduct, and externally rotate the hip -surgical reduction and casting -osteotomies: stress maneuvers not done with harness on, harness is ONLY removed if requested out of harness with and without stress
What are the hip flexor muscles?
-psoas major -iliacus -quadriceps femoris; rectus femoris -sartorius
What are the primary flexors of the hip and what is it brought back by?
-psoas major, iliacus, rectus femoris -brought back by: hamstrings , gluteus maximus
beta angle (β)
-reflects changes in the cartilaginous acetabulum(labrum), which occurs more quickly than do changes in the osseous acetabulum -normally less than 55 degrees
What are the hip extensor muscles (hamstring group) and where do they each originate?
-semitendinosus: originates at the ischial tuberosity -biceps femoris: originates at the ischial tuberosity and posterior femur -semimembranosus: originates at the ischial tuberosity
Describe hip mobility movement.
-somewhat limited in range -due to the tight fit between the femur and acetabulum -hip bone is immobile -sonographic evaluation: primarily concerned with abduction and adduction motions
subluxed neonatal hip
-subluxed superiorly. -rounded/indented ilium-acetabular roof angle (Green). -abnormally elevated labrum (yellow) -femoral head (red circle) would produce an abnormally shallow alpha angle
hip joint
-surrounded by a tough capsule -attaches to the intertrochanteric line of the femur -attached by its apex to the anterior spine of the ilium and rim of the acetabulum -attached inferiorly to the intertrochanteric line of the femur -limits extension of the hip joint
dislocation of the hip: newborn (4-6 weeks)
-the femoral head may be dislocated in a lateral position or posterosuperior position (both relative to the acetabulum) -femoral head can be reduced without deformity to the joint
What are the functions of the tendons and ligaments?
-they are soft collagenous tissues -tendons connect muscles to bone -ligaments connect bone to bone -both play a significant role in musculoskeletal biomechanics
transverse view position
-transducer at 90 degrees to the position in coronal view. -hip flexion (rest, stress) -stress: gentle push of femur towards hip. (Baby in oblique) -move the transducer posteriorly to a posterolateral position on the hip joint
femur
-upper thigh bone -most superior portion of the hip bone -surrounded by muscles, ligaments, and tendons -articulates with the acetabulum of the hip bone
Abnormal hip placement diagnosed up to ______ to _____ weeks of age is due to normal laxity of the hips.
4 to 6 weeks
At what age is ultrasound of the infant hip best performed.
6 months of age
What percent of mild abnormal hip placement cases may resolve?
90%
What are the risk factors of hip dislocation?
12 to 16% of all newborns have one or more of the salient risk factors: -oligohydramnios during pregnancy (not enough fluid for the fetus to move around) -breech presentation -first pregnancy -female babies (male to female ration 1.5-5.8) -family history (sibling 6%, parents 12%) -increased birth weight -infants swaddled dramatically during early infancy (believed to be prevalent among certain North American tribe and Asian decent) (more prevalent among winter months) -foot deformities -torticollis
The rotation range that occurs at the head of the femur ranges up to _____ % to the shaft of the femur.
120%
What is the strongest ligament in the body?
iliofemoral ligament
What is the most important ligament?
iliofemoral ligament
Which view, position, and hip is seen in this ultrasound image?
right hip, coronal, flexion/abduction
asymmetric skin folds
thigh creases are uneven, there are more creases on the right than left
What are causes of proximal femoral focal deficiency?
-in utero vascular event -associated with numerous syndromes
What are some pitfalls/difficulties when scanning for hip effusion?
-muscles of the joint can often look hypoechoic or even anechoic and mimic fluid or if gain is too low -the hip joint and synovial space is seen under the joint capsule(hyperechoic line anterior purple line)yellow arrow -the cartilage of the hip joint has low level echoes (yellow arrow)for effusion
Transient synovitis of the hip is an acute inflammatory condition of the inner lining of the hip that goes away in _____ to _____weeks.
2 to 3 weeks
The primary flexors of the hip are limited to _____ %.
20%
What imaging modalities can be used to scan for proximal femoral focal deficiency?
radiology, sonography, MRI -sonography is not definitive but may be able to identify presence or absence of the femoral head or a lack of connection between femoral head and shaft
Proximal Femoral Focal Deficiency (PFFD)
rare and congenital anomaly involving proximal femur and acetabulum -decreased ossification -absence of hip joint with shortening or absence of femur -clinically, it may present with short lower extremity
Which view, position, and hip is seen in this ultrasound image?
right hip, coronal, neutral
Which view, position, and hip is seen in this ultrasound image?
right hip, transverse, flexion/adduction/push
What pathology is seen in this ultrasound image?
septic arthritis
What pathology is seen in this ultrasound image?
subluxed neonatal hip
What is labelled in this ultrasound image of hip effusion?
the hip joint and synovial space is seen under the joint capsule (hyperechoic line anterior purple line) yellow arrow; the cartilage of the hip joint has low level echoes (yellow arrow) for effusion
What does an abnormal amount of synovial space cause?
this much fluid in the space inferior to the capsule and joint represents a hip joint effusion
