community acquired MRSA pyomyositis of thigh or pelvic muscles
more common in tropics
rare in temperate climates but frequency is increasing with prevalence of MRSA pvl-positive USA300 strains in the community 1)
PVL is an exotoxin that forms pores and induces polymorphonuclear leukocyte death by apoptosis, and is associated with deep-seated furunculosis, and it may be that it has a propensity to infect damaged muscle tissue following minor trauma or strenuous activity
overuse injury causing worsening hip/thigh pain esp. on internal rotation and with hopping ⇒ bone scan or MRI
NB. performing a single-leg hopping test in a patient with a potential FNSF is risky and may cause completion of the stress fracture - instead, test in supine position with axial loading on the heel
tendonitis
overuse injury, local tenderness, pain increases with activity, “snapping” weakness ⇒ USS or MRI
iliopsoas tendinitis
esp. overuse with repeated hip flexion or external rotation of the femur, rheumatoid arthritis
iliopsoas bursitis
this bursa lies between the psoas muscle and the anterior aspect of the femoral head
typically occurs when people with tight hip flexors from sedentary jobs with prolonged sitting decide to do a long uphill hike or take up uphill running, can also occur in gymnasts, track and field sports and dancing.
theoretically pressure over the ant. hip from tight low-slung backpack waist belts may be a contributory cause for hikers
the tightness and pain in the iliopsoas may also be secondary spasm if there is underlying labral tear or femoral ligt strain
severe ant. hip pain radiating to knee worse on hip extension such as when getting up from a seated position or hanging up the washing
pain worse when patient is supine and raises both heels 15deg
Dx: clinical, or MRI or US may show an enlarged bursa
Rx with rest, NSAIDs, hip flexor stretch exercises
pressure from a large bursa has been known to cause femoral V thrombosis
acute muscle strains ⇒ USS or MRI
rupture of tendon insertions:
ASIS - sartorius
AIIS - rectus femorus
pubic symphysis - adductors
ischael tuberosity - hamstrings
lesser trochanter - iliopsoas
greater trochanter - gluteals
iliac crest - abdominal muscles
sports hernia / tear of oblique aponeurosis
chronic groin pain esp. soccer/rugby/ice hockey players; pain worse with “cutting”/sprinting
tender superficial inguinal ring
+/- obturator or ilioinguinal nerve entrapment ⇒ adductor weakness or spasm / decreased sensation
osteitis pubis
midline pubic pain with radiation to hip; worse with striding or pivoting;
tenderness; pain on adduction; limited rotation and obliquity ⇒ bone scan
“When presented with an acutely irritable hip, no single test (other than the gold standard hip arthrocentesis) can reliably differentiate between septic arthritis and transient synovitis. The predicted probability for septic arthritis appears to increase with the cumulative presence of: the presence of fever >38.5, refusal to weight bear, serum WCC > 12, ESR >40mm/hr, CRP >20 mg/dL and a previous health care visit for the same complaint. Further validation of the proposed algorithms is required. There is some evidence that CRP is more sensitive than ESR.”
investigations of the child with an acute non-traumatic limp
the New Zealand study reported in EMA April 2009
in 350 children studied with an acute non-traumatic limp in New Zealand5), the following was found:
286 final diagnosis of irritable hip, 7 (2%) septic hip (all were aged < 5yrs old), 30 (8%) osteomyelitis, 9 had SUFE, 1 had Perthe's disease.
21 (6%) had abnormal Xrays making the suggestion that perhaps hip Xrays were NOT indicated in these cases for children under 9 years of age (over 9 years of age they are much more important in excluding SUFE which was present in 18% of all those Xrayed aged 9 and over, and in the Maori/Islander population, the youngest was 8 yrs old).
hip Xrays are NOT useful in diagnosis of hip effusions, osteomyelitis or early stages of Perthe's disease.
tibial Xrays ARE useful if one suspects Toddler's fracture (spiral fracture of tibia shaft usually with minimal clinical findings or history), or non-accidental injury.
the optimum inflammatory marker appeared to be a CRP > 12 which gave a sens. of 87% and spec. 91% for septic hip or osteomyelitis - either diagnosis made more likely if there was also either fever, non-weight-bearing, raised WCC, or raised ESR.
given the low incidence of bacterial infection, ultrasound-guided hip aspiration is probably unnecessarily invasive.
hip ultrasound is NOT generally helpful as it cannot distinguish between septic arthritis or a reactive arthritis, and usually the presence of clinically irritable hip suggests an effusion will be present. It's utility would primarily lay if one were to then perform an US-guided hip aspiration if effusion were found.
inflammatory markers are probably unnecessary in a well looking, afebrile child who is mobile but limping and has had symptoms for 48hrs or less, as the probability of missing bacterial infection in this group is very low.
an approach to the atraumatic limping child
age 9 yrs or older with pain on internal/external rotation of hip (may present with knee pain!):
strongly suspect slipped upper femoral epiphysis and keep non-weight bearing until proven otherwise
Xray hips - if in doubt discuss with radiologist or orthopaedics team.
irritable hip can still occur in the older child but 85% of cases occur in the 1st decade of life
adolescents also tend to develop chondrities from over-use (such as Kohler's disease, etc) as well as mechanical pain such as from patello-femoral issues.
age 2 yrs of younger:
examine carefully for local causes (eg. foreign body in foot, hot foot suggestive of osteomyelitis)
consider non-accidental injury
if no obvious cause found then:
if internal/external rotation of hips is relatively pain free, strongly consider Toddler fracture and Xray tibia
if internal/external rotation of hips is painful then hip effusion is most likely to be present (thus US not usually helpful) and most likely diagnosis is irritable hip and thus manage as for older children (see below)
any age child with presumed “irritable hip”:
if well looking, afebrile child who is mobile but limping and has had symptoms for 48hrs or less then discharge home with advice to return if becomes unwell, febrile, worsening pain or prolonged pain > 48 hours.
otherwise, take blood for FBE, ESR and CRP
if all are normal (WCC < 12,000, ESR < 30, CRP < 12) then bacterial infection is very unlikely but not fully excluded
if any of these are elevated, consult with orthopaedic team for inpatient Mx of presumed bacterial infection.