Category Archives: Orthopaedic

HACEK organisms

Cardiology, General paediatrics, Microbiology, Orthopaedic

Group of similar gram negative, low pathogenicity organisms – not actually related to each other, but cause similar infections:

  • Haemophilus (usually parainfluenzae, not H. influenzae which rarely causes endocarditis)
  • Aggregatibacter actinomycetemcomitans (prev Actinobacillus)
  • Cardiobacterium hominis
  • Eikenella corrodens
  • Kingella kingae

Commensals of the mouth – usually just cause dental infections but can cause endocarditis (gram positives are the usual cause) and osteomyelitis (esp Kingella – named after Elizabeth King – can be spread by respiratory route, so outbreaks of septic arthritis!).

May grow on chocolate agar but not the McConkey you usually use for gram negatives. Some beta-lactamase but most susceptible to cefalosporins.

Hemihypertrophy

General paediatrics, Genetics, Haem/Oncology, Orthopaedic

=Asymmetric overgrowth of one limb, or one side of the body, or just one side of the face.

Can be associated asymmetric overgrowth of internal organs.

Can be an isolated finding (of unknown cause) or associated with syndromes such as Beckwith-Wiedmann, Klippel-Trenaunay-Weber, or McCune-Albright syndromes.

Essentially a cosmetic problem. But increased risk of tumours, including Wilm’s tumour, adrenal cell carcinoma, hepatoblastoma and small bowel sarcoma.

Risk of tumour development in isolated hemihyperplasia is about 1 in 20 or approximately 5%. Given that oldest reported case was 6yrs and shortest interval between tumour presentation and ultrasound was 5 months, suggested hat till age of 6 years these children should have abdominal ultrasound scans at three monthly intervals.

Radial dysplasia

General paediatrics, Genetics, Orthopaedic

Spectrum of congenital abnormalities of hand and forearm, from hypoplastic or absent thumb, to short arm with deviated, clubbed hand.

Commonly part of a congenital syndrome, so refer to a clinical geneticist.

  • VACTERL Association,
  • VATER syndrome,
  • Holt-Oram syndrome ( association of cardiopulmonary and limb defects),
  • TAR syndrome (thrombocytopenia-absent radius),
  • Fanconi anaemia.  

Investigations

  • Spine x-rays,
  • renal ultrasound,
  • complete blood count,
  • echocardiography

Osteogenesis imperfecta

General paediatrics, Orthopaedic

Recurrent fractures, often with minimal trauma, family history. Joint and bone pain can be an issue even without fractures.

No single test for osteogenesis imperfecta.  Clues might be deformities, short stature, hypermobility and poor dentition.

Type 1 is most mild, no deformities. Type 2 lethal in early life, antenatal scan may show chest wall abnormality and respiratory failure often at birth.

Type 3 is severe, with fractures in the womb or during birth. Short stature, deformities marked.

Type 4 variable, may only be diagnosed later in life. Type 5 associated with excessive callus formation.

Bisphosphonate infusions are used for the most severely affected. Otherwise, management revolves around:

  • Fracture and pain management
  • Aids eg wheelchairs
  • Physiotherapy, esp if immobile due to fractures

Osteoporosis

General paediatrics, Medical, Orthopaedic

Various causes of secondary osteoporosis: coeliac disease,  hyperthyroidism, hypogonadism, IBD, chronic liver disease, JIA, chronic renal, immobility.

Consider calculating fracture risk if secondary osteoporosis or previous fragility fracture, frequent use of systemic steroids, FH hip fracture, low BMI, smoking/alcohol etc.

Use online tools FRAX or QFracture to estimate 10yr predicted fracture risk (FRAX includes previous bone mineral density value if DXA done, not necessary).  If risk is in the region of “intervention threshold” for proposed treatment, consider doing DXA and recalculate FRAX.  Tools may underestimate risk if history of multiple fractures, previous vertebral fracture, high dose steroids, other causes of secondary osteoporosis. These tools are meant for adults over 30-40yrs however.

“Intervention thresholds” are NOT covered in guideline, it says see local guidance!

For WOS, no Dexa for coeliac until in 20s.

[NICE osteoporosis guideline ]

Rickets

General paediatrics, Nutrition, Orthopaedic

Acquired bone disease, due to vitamin D deficiency. In UK, mostly black and Asian children, due to dark skin and low levels of sun exposure, also diets often rich in phytates and oxalates.

More common in boys, perhaps due to higher bone mineral density.

Safeguarding concerns note uncommon.  2 deaths reported in BPSU study, multiple risk factors, rickets only diagnosed post mortem

Clinically:

  • Leg deformity (bowing or knock-knees)/Swollen wrists or knees or ankles or ribs (rachitic rosary), AND
  • 25OH vitamin D <25nmol/L PLUS one or more abnormalities of serum calcium, alkaline phosphatase, phosphate, parathyroid hormone

Else radiological Rickets:

  • Widening, cupping, splaying of metaphysis (of any long bone) AND
  • 25OH vitamin D <25nmol/L

Other clinical features:

  • Delayed motor development 
  • Pain, limp

These are strict research definitions – some cases seen with abnormal PTH and radiological features but have dietary calcium deficiency and less severe vitamin D insufficiency (between 25 and 50), these would be called nutritional rather than Vit D deficiency rickets.  There is no clear cut off below which rickets occurs!

Incidence seemed to be rising but not borne out in most recent BPSU study (2020).

Differential

  • Vitamin D dependent rickets e.g. 1α hydroxylase deficiency
  • Vitamin D resistant rickets e.g. familial or X-linked hypophosphataemic rickets
  • Rickets associated with other chronic diseases e.g. malabsorption, liver disease, chronic renal disease
  • Metabolic Bone Disease of Prematurity (infants whose corrected age is < 3 months at presentation, who were born < 36 weeks gestation and weighing <1.5kg

Complications

  • Often cow’s milk allergy seen, else these are usually breast fed babies.
  • Fractures (usually femoral) can be a clue.
  • Hypocalcaemic seizures
  • Dilated cardiomyopathy can be seen, usually in older children where bone growth is more advanced already. Worth an echo!

Evidence from BPSU study that DOH guidance on Vitamin D supplementation not being followed, either in mothers or children themselves.

Wide variation in Vitamin D treatment prescriptions. Alfa-calcidol is potentially toxic and should be avoided.

Lower limb variants

Clinical, Common, General paediatrics, OPD, Orthopaedic

Beware 2 problems, with additive or compensatory effects e.g. foot and hip!

Rotation probs ie in-toeing and out-toeing.

Metatarsus adductus is common.  Outer edge of foot is curved, and vertical line through heel misses 2nd/3rd toe space.  Rigid forms need serial casting, else 90% improve without treatment by 6-9 months of age.

Internal tibial torsion can be seen by keeping patellae parallel (sitting, or kneeling), and seeing angle of foot.  No treatment required unless severe (tibial rotational osteotomy).

Femoral ante version is more common in girls and often familial.  W posture sitting, patella points in, eggbeater pattern running.  80% resolve spontaneously, else osteotomy (but high rate of complications).

Out toeing normal in first 24 months.  Usually external tibial torsion; occ femoral retroversion.  External tibial torsion associated with patellofemoral instability.  Beware Perthes and SUFE in school age children, esp  unilateral.

Pes Planus – Flexible or rigid?  Arch reforms on tiptoeing?  Rigid suggests congenital vertical talus (rocker bottom heel) or JIA, either way, usually painful.  Beware CP or muscular dystrophy or connective tissue disorder.  Asymptomatic is considered benign.  Insoles may be useful for pain and shoe deformation, do not correct flat foot!

Angular problems ie genu varum/valgum

(Bow/knock)  Gap between knees (intercondylar distance) should be <6cm, gap between ankles (intermalleolar) should be <8cm.  Beware rickets, renal osteodysplasia, tumours, skeletal dysplasias.  Note association between high impact sport and genu varum – cause or selection?  Increased risk of injury/OA in later life…  Differential includes Blounts disease (also associated with obesity).

Knock knees exacerbated by external tibial torsion, ligamentous laxity, obesity.  Less typical pattern of rickets but seen.

[Yeo, BMJ 2015;351:h3394 – videos too]

 

Chronic Recurrent Multifocal Osteomyelitis

General paediatrics, Infectious disease, Orthopaedic

Adolescents, longbones, probably 1% of all osteomyelitis. ?mech – biopsies usually negative on culture! Pain, ?arthritis if adjacent to focus. Associated with:

  • pyoderma gangrenosum
  • uveitis
  • palmar plantar pustulosis (as in psoriasis)
  • IBD (may come later)

ie inflammatory, autoimmune sounding. Osteolytic & sclerotic lesions on XR, hotspots on bone scan. Histology not characteristic. Differential diagnosis is Langerhans cell histiocytosis.

Rx NSAIDs, steroids if severe/recurrent, ?pamidronate, ?infliximab.

Self limiting but relapsing over 2-4 yrs. 1 case series showed high rate of deformity, but the largest found no long term complications at all!

Osteomyelitis

General paediatrics, Infectious disease, Orthopaedic

Bone infection.  Caused either by haematogenous spread (from distant site), direct innoculation (trauma) or spread from adjacent focus (eg otitis media).

Can be acute or more indolent eg 2/52+ symptoms (Brodie abcess). Mostly femur, tibia, humerus but can be anywhere. Up to 20% multifocal. Pelvic disease often presents with abdo/lumbar pain!

Septic arthritis – similar to OM, usually due to bacteraemia, same organisms. Potential for growth plate or joint consequences. Can lead to OM and vice versa.

Discitis – same bugs (probably), generally under 3-5yrs only, due to persistence of blood vessels in cartilage that subsequently atrophy – can mimic vertebral OM. Well, blood culture neg (cf vertebral osteomyelitis – >3yr, toxic, blood culture pos). Rx clindamycin for 2/52 but no evidence! Likely that some of these would resolve spontaneously if untreated.

Note also Chronic recurrent multifocal Osteomyelitis (CRMO) – clue is in the name! Sterile. Treat with NSAIDS.

Neonatal

Neonatal cases have wider range of organisms and generally involve both bone and joint.  Approx 50% have no systemic features, present with pseudoparalysis alone.

Bugs

Epidemiology varies. MRSA predominant in US etc.

Staph aureus is the main cause, plus:

  • Neonates – GBS, candida, enterobacteriae
  • Infant – kingella, rarely pneumococc, GAS, haemophilus (type B and others), MRSA.
  • Penetrating injuries – risk of contamination, so odd organisms

Kingella, incidentally, is often resistant to vanc and clinda!

Beware salmonella (sickle cell), meningococcal (gonococcal too), TB and non tuberculous mycobateria.  But unknown in up to half, PCR vs culture…

Panton Valentine Leucocidin toxin positive associated with higher fever, higher inflammatory markers, multiple sites, chronic/recurrent.

Radiology

X-ray shows mixture of fast (cortical breach, lysis) and slow (sclerosis, periosteal reaction) changes – but non-specific.

Abscess with sinus extending into soft tissue is indicative of infection.

Fistula and sequestrum (isolated bit of dead bone) more suggestive but take 1-2 weeks to develop.

“Onion skin appearance” suggests chronic infection but is also seen in normal infants, malignancy and in retinoid therapy.

USS may show sub-periosteal oedema early on.

MRI standard for defining collections and guiding surgery: 92-97% sens cf 64-71% for bone scan (latter is also operator dependent).

Investigations

CRP better than ESR.  But can (like WBC) be normal.

Bone biopsy rarely done unless cancer suspected. Joint/pus aspiration can be useful, but generally diagnosis relies on blood culture, hence low identification rates. New PCR technique for Kingella from conventional culture media.

Treatment

Surgical drainage if collection identified or poor response after 48-72hrs in absence of resistance. But still not well defined – over 1 yr and delayed presentation seems to have worse prognosis but will also depend on virulence and resistance.

A septic hip should always be drained promptly, but less clear for other sites – some still advocate early intervention given potential for rapid joint destruction. Aspiration and irrigation probably adequate for most, with second line open arthrotomy (laparoscopic view is limited)

Immobilization +/- traction are considered good practice. For SA, window of 4hrs considered acceptable to get samples before starting antibiotics.

Poor evidence for antibiotic treatment.  Current recommendations:

Cefuroxime under <6yrs (non-neonatal) else Fluclox  or clinda. Beware PVL staph, Hib unimmunized and risk factors for MRSA.  Broad spectrum if neonate, immuncompromised or sickle cell disease.

For all antibiotics use the maximum dose. Never give rifampicin monotherapy as resistance quickly induced. Beware erythromycin resistant MRSA and clinda (inducible resistance). Teico good for bone (keep level>10).

Switch to oral when clinically improved +/- CRP response (eg<20 or down more than 2/3 of peak), median 4 days.  Under 3 months, give full 4/52 treatment course IV.

Failure to improve –

  • consider metastatic infection, DVT, unusual organism eg Fusobacterium. PVL pos
  • IV for 21 days minimum, total 6/52 minimum (even SA)
  • HPA recommend max dose clinda, rifamp AND linezolid. Max 4/52 linez – neuropathy.

Total duration 4-6 weeks for OM, in textbooks, 3 weeks for SA.

Recent HPA guidelines suggest initial therapy for deep seated PVL positive Staphylococcus aureus infections in children as intravenous clindamycin plus rifampicin and linezolid (linezolid maximum of 4 weeks due to the risk of development of peripheral neuropathy), followed by clindamycin plus rifampicin.  Beware thrombosis.

Shorter courses eg 10 days? Peltola’s Finnish studies of shorter courses may not be applicable, as possibly selected for milder infection, exclude culture negative but have high rates of positive diagnosis (staph). [Current Opinion in Pediatrics. 25(1):58-63, 2013 Feb. UI: 23283291] Howard-Jones & Isaacs in JPedsCH however feel evidence for 3/52 courses (grade 2B), emphasize QDS dosing. 1 small old study suggested nafcillin/methicillin inferior to cefuroxime, so Clinda preferable to Fluclox. [Jourrnal of Paediatrics and Child Health 49 (2013) 760–76 UI: 23745943]

[Saul Faust Arch Dis Child 2012;97:545–553. doi:10.1136/archdischild-2011-301089]