irritable hip

definition

·      syn. transient synovitis

·      syndrome characterised by

·      acute onset of hip pain and stiffness

·      no systemic illness

·      complete resolution

epidemiology

·      most common cause of hip pain

·      reported incidence is 1 in 1000

·      may occurin 3% of children with majority not seeking medical attention

·      wide range of age

·      from 9 months to adolescence

·      usually between age 3 and 8 yrs

·      peak age is 6 yrs

·      more common in

·      boys (2:1)

·      whites

·      never bilateral

aetiology

·      unclear

Infection

·      may be infectious or post-infectious condition

·      supported by frequent association with current or antecedal illness

·      viral or bacterial

·      most commonly ENT

·      no specific viral antibodies found

Trauma

·      may be contusion of hip

·      history of trauma in 30%

Allergic hypersensitivity

·      may be hypersensitivy response

·      25% of patients have allergic predisposition

·      dramatic response to antihistamines and steroids

pathology
Histology

·      culture-negative synovial effusion

·      synovial hypertrophy secondary to nonpyogenic inflammatory reaction

Natural history

·      limited duration of symptoms

·      average 10 days

·      may be as long as 8 weeks

·      recurrence uncommon

·      < 10%

·      may be mild radiographic changes in hip

·      coxa magna and femoral neck widening

·      probably 2o to local hypervascularisation

·      not symptomatic

·      association with Perthes disease in 1.5%

·      probably nat causative

clinical
Presentation

·      acute onset of unilateral hip pain

·      usually hip and groin

·      may be thigh and knee

Findings

·      limp

·      inability to weight bear

·      hip held in flexion and external rotation

·      protective muscle spasm

·      restricted ROM, esp. IR

·      may be low-grade fever (< 38o)

investigations
Laboratory

·      may be mild elevation of

·      WCC

·      ESR

·      CRP

Radiology

Plain x-ray

·      usually normal

·      performed to exclude other conditions

Ultrasound

·      may show effusion

Bone scan

·      shows variable pattern

·      routine use not indicated

differential diagnosis

·      Perthes disease

·      septic arthritis

·      osteomyelitis

·      juvenile rhemoatoid arthritis

·      slipped femoral epiphysis

Treatment

·      symptomatic

·      shown to decrease recovery time and recurrence

·      bed rest and analgesia until full ROM achieved

·      admission only for severe cases where diagnosis unclear

·      traction only for severe cases that fail to settle

·      may add NSAIDs

·      partial weight bearing on crutches until limp resolves