Chapter 46- The Child's Hip

Question 1

In a child with a trendelenberg limp, what is the limp diagnostic calendar

Answer 1

• 1-5 years- missed congenital dislocation of the hip
• 5-10 years- perthes disease
• 10-15 years- slipped upper femoral epiphyses
• septic arthritis and transient synovitis of the hip can present at any age

Question 2

What is developmental dysplasia of the hip

Answer 2

• idiopathic hip dysplasia
• it includes dislocation at birth and acetabular dysplasia where the hip is located, patient becomes symptomatic later in life because acetabulum has not developed normally

Question 3

Ligamentous laxity contributes to developmental dysplasia of the hip. What causes ligamentous laxity

Answer 3

• sensitivity to female perinatal hormone relaxin

Question 4

Mechanical factors contributing to developemental dysplasia of the hip

Answer 4

• in utero: increased incidence in Breech, first born and oligohydramnios
• Postnatal: swaddling eg by native americans

Question 5

Pathology of developmental dysplasia of the hip

Answer 5

Hip dislocates supero-laterally and capsule develops in an hourglass deformity with the inferior capusle being the main obstruction to reduction. Acetabulum becomes more dysplastic with deficient antero-lateral cove.

Question 6

Describe the tests done in the neonatal period to test for hip instability

Answer 6

• Ortolani: dislocated hip relocates with abduction of the hip
• Barlow: hip located but unstable and dislocates with adduction

Question 7

What test is indicated in patients at high risk for developmental dysplasia of the hip and when is the ideal time for this test

Answer 7

• Ultrasound (more sensitive than clinical exam)

- Ideal time is at 6 weeks

Question 8

Describe a patient at high risk for developmental dysplasia of the hip

Answer 8

• positive family history
• First born
• Breech
• Barlow positive hip
• any ‘suspicious’ hip

Question 9

Describe the AP pelvis radiograph in developmental dysplasia of the hip

Answer 9

• Femoral epiphyses only apparent at 6 months, therefore special lines are required to show superolateral dislocation.
• Shenton’s line (joining inferior femoral neck with inferior pubic ramus) is broken
• Metaphysis of femoral neck lies laterally to a line drawn from the lateral border of the acetabulum

Question 10

What may an untreated dislocated hip in a child eventually lead to

Answer 10

• Adequate treatment prevents a trendelenburg, short leg limp
• Stiff, painful hip due to avascular necrosis is often due to treatment only

Question 11

Treatment of dislocation based on age?

Answer 11

• <6 months: Pavlik harness
• 6- 18 months: traction, closed reduction and spica
• > 18 m: Open reduction, pelvic osteotomy +- femoral osteotomy

Question 12

What position does the pavlik harness hold the hips in?

Answer 12

-Hips in flexion and abduction but allows mobility

Question 13

What is the complication of treatment of developmental dysplasia of the hip

Answer 13

• Avascular necrosis
• Caused by splinting of the hip in more than 40 degrees of abduction in the pavlik harness or spica. or with a tight open reduction (femoral shortening reduces the chance of avascular necrosis

Question 14

Average age of presentation of SUFE

Answer 14

• Boys: 14

- Girls: 12

Question 15

Main complications of SUFE

Answer 15

• Avascular necrosis

- Chondrolysis

Question 16

What are the current theories of the cause of SUFE

Answer 16

• Hormonal: Sex hormones close the growth plate and growth hormone increases the thickness of the growth plate, and therefore makes it weaker
• Retroversion: Increased retroversion of the femoral neck predisposes the femoral head to slip posteriorly
• Trauma: repetitive trauma in obese patients acting of an abnormal growth plate could be a factor
• Hereditary

Question 17

Definite causes of SUFE

Answer 17

• Primary hypothyroidism
• Pituitary tumours
• Hypogonadism
• Renal rickets

Question 18

Clinical presentation of SUFE

Answer 18

• Hip pain often referred to the knee
• 50 percent are overweight
• Antalgic, trendelenberg and possibly short limb limp
• decreased abduction and internal rotation of the hip
• Hip goes into external rotation when flexing because anteriorly displaced femoral neck blocks internal rotation
• Acute slip: duration of symptoms less than 3 weeks
• Chronic slip: Duration more than three weeks
• Acute on chronic: sudden exacerbation of chronic symptoms

Question 19

Stable vs unstable SUFE

Answer 19

• Stable: patient can weight bear with or without crutches. no AVN
• Unstable: cannot weight bear with or without crutches. 10 percent develop AVN

Question 20

Findings on radiograph in SUFE (Ap and frog lateral)

Answer 20

• AP: minimal slip shows a widened and irregular physis. An established slip has a positve Trethowan’s sign: a line along the superior aspect of the neck remains superior to the head instead of going through it.
• Lateral radiograph: Positive Capener’s sign: femoral head lies outside the acetabulum

Question 21

How is the percentage slip determined in SUFE and how does this relate to the severity

Answer 21

• Percentage slip is determined on lateral view by the Wilson percentage method or the head shaft angle
• Mild: < 30% slip or 30 degrees
• Moderate: 30- 50 % slip or 30-60 degrees
• Severe: > 50 % slip or >60 degrees

Question 22

Treatment of mild to moderate SUFE

Answer 22

Pinning in situ is achieved by one screw placed in the centre of the epiphyses and 90 degrees to the growth plate

Question 23

Treatment of severe SUFE

Answer 23

-If slip is unpinnable, slow reduction of the hip with traction in abduction and internal rotation over a few days has a low incidence of AVN

Question 24

What is Perthe’s disease

Answer 24

-Partial or total avascular necrosis of the femoral head, in contrast to other causes of AVN, the femoral head recovers

Question 25

Etiology of perthes disease

Answer 25

• Recurrent infarction occurs
• Etiology is unknown
• Blood supply from 3-10 years is limited to the lateral retinacular vessel only, the metaphyseal vessels disappear after 2 years
• The lateral retinacular vessel is vulnerable to changes of pressure in the hip capsule

Question 26

What are the three stages of Perthes disease

Answer 26

• Avascular stage: Femoral head can be normal. joint space is increased. Subchondral fracture occurs when trabeculae collapse. Finally the head becomes sclerotic
• Revascularisation phase: Dead bone is removed by ‘creeping substitution and the femoral head looks cystic and fragmented
• Healing stage: Subchondral ossification occurs. whole process up till now takes up to one year. the healing process is only completed after 2-4 years and the final shape of the head (spherical, oval or flat) becomes obvious at maturity

Question 27

Clincal presentation of Perthes disease

Answer 27

• Antalgic and trendelenberg limp

- Decreased abduction and external rotation

Question 28

How does one classify Perthes disease according to the Catterall groups?

Answer 28

1: anterior quarter
2: Anterior half (lateral pillar intact)
3: lateral three quarters (lateral pillar involved)
4: whole head involvement

Question 29

What is the goal of treatment in Perthes disease

Answer 29

-Protect the femoral head during biologically plastic or soft stage (during avascular and revascularisation phases) and prevent it from becoming flat instead of spherical

Question 30

Definitive treatment of Perthes ?

Answer 30

Includes:

• Containment: by abducting the hip the lateral pillar is protected by the acetabulum
• Movement for cartilage nutrition
• Some believe non weight bearing also plays a role

Question 31

Conservative treatment of Perthes disease

Answer 31

-Abduction plasters or splints (weight bearing and non-weight bearing) for about one year until subchondral ossification occurs and deformity of the femoral head cannot occur

Question 32

Surgical treatment of Perthes

Answer 32

• Pelvic Osteotomy: salter (<8), Chiari, Shelf

- Femoral osteotomy

Question 33

Prognostic Factors of Perthes disease

Answer 33

• Age ( > 8 years)

- Lateral pillar involvement