Perthes Disease

Question 1

what is perthes disease?

Answer 1

avn of femoral head
in children 4-8y

Question 2

how does perthes disease present?

Answer 2

gradual onest limp and hip pain
pain can be referred to knee

Question 3

how to differentiate perthes disease from transient synovitis?

Answer 3

pain is similar but only 2 weeks in transient synovitis
pain >4 weeks raises suspicion for perthes

Question 4

mx of perthes disease?

Answer 4

depends on extent of necrosis

if <50% femoral head - resolves with conservative measures (bed rest, traction), good prognosis

if >50% femoral head - plaster cast with hip abducted or osteotomy, poor prognosis + high risk of degen arthritis

Question 5

epidemiology of perthes?

Answer 5

5x more common in boys
10% cases bilateral

Question 6

dx of perthes?

Answer 6

hip x-ray - shows sclerosis and fragmentation of epiphysis

may be initially normal so needs to be repeated later if clinical suspicion persists

Question 7

what is a limp?

Answer 7

a clinical presentation - not a diagnosis

asymmetric gait
deviation from normal age-appropriate gait pattern

Question 8

what can cause a limp?

Answer 8

secondary to pain, weakness, deformity due to different causes (e.g. transient synovitis, septic arthritis, malignancy)

Question 9

what are red flags in a child presenting with a limp?

Answer 9

pain waking child at night - malignancy
redness/swelling/stiffness of joint - infection, inflammatory disease
FLAWs - malignancy, infection, inflammation
rash/bruising - haematological/inflammatory/maltreatment
unable to WB - trauma, infection
palpable mass - malignancy/infection
symptoms worse in mroning - inflammatory

Question 10

referral criteria for urgent specialist assessment in child w limp?

Answer 10

• fever and/or red flags
• ?maltreatment
• <3y (septic arthritis more common than transient syno)
• > 9y with pain or restricted hip movement (exclude SUFE)