Rickets, TS, Reactive + Septic Arthritis

Question 1

What is Rickets, how does it differentiate from Osteomalacia?

Answer 1

• Failure in mineralisation of the growing born or osteoid tissue.
• Failure in mineralisation of mature bone is osteomalacia.

Question 2

Risk factors for Rickets?

Answer 2

1) Decreased sunlight
2) Dark skin
3) Maternal vitamin D deficiency
4) Diet deficient in calcium, phosphorus and Vitamin D (exclusively breastfed till late infancy)
5) Vegan diet
6) Intestinal malabsorption - coeliac, cystic fibrosis, pancreatic insufficiency.
7) Drugs - Anticonvulsants interfere with Vitamin D metabolism
8) Chronic liver and renal disease

Question 3

Rickets Ppx:

Answer 3

• Rickets due to profound Vitamin D deficiency - VIt D required for Ca2+ and phosphate absorption which are incorporated into the bone.
• Vit D produced in skin through sunlight, and some obtained from dietary sources such as oily fish, egg yolks and margarine.
• Vit D is converted to in the liver, 25-hydroxy Vit D, which is again converted to Calcitriol in the kidney.
• CALCITRIOL is active Vit D and promotes Ca2+ absorption in intesting and reabsorption of calcium and phosphate in kidney.

Question 4

Presentation of Rickets?

Answer 4

1) Craniotabes - depression of skull elicited by pressing firmly over the occipital and posterior parietal bones (ping pong ball)
2) Costochondral junctions palpable - rachitic rosary
3) Wrists (crawling infants) and ankles may be widened
4) Horizontal groove along the lower border of thorax (costal insertion with the diaphragm) - Harrison’ sulcus
5) Failure to thrive
6) Bowing of weight-bearing bones - CHARACTERISTIC
7) Seizures (late)

Question 5

Diagnosis of Rickets?

Answer 5

1) Bloods - low serum calcium, phosphorous levels low, low hydroxyvitamin D, PTH elevated, and plasma alkaline phosphatase activity is raised.
2) Dietary history of vitamin and calcium intake.
3) X-ray of wrist - cupping and fraying of metaphyses and a widened epiphyseal plate.

Question 6

Treatment of Rickets?

Answer 6

1) Balanced diet/correct predisposing risk factors
2) Daily administration of vitamin D3 - cholecalciferol
3) Treat cause (kidney/liver disease)
4) Healing occurs in 2-4 weeks - lowering alkaline phosphatase, increasing vitamin D levels, healing on X-ray.
5) Complete reversal of bony deformities may take several years.

Question 7

Transient Synovitis (irritable hip) Ex and Ax?

Answer 7

1) 2-12 years old
2) Followed or accompanied by infection often
3) Most common cause of hip pain (acute)

Ax: Viral illness (recent viral URTI precedes), autoimmune, trauma

Question 8

Presentation of Transient Synovitis?

Answer 8

1) Acute onset hip pain (sudden)
2) Refusal to bear weight on affected extremity - limp
3) No pain at rest but decreased range of movement (internal rotation)
4) Pain radiating to knee?
5) Afebrile or mild fever (not ill)

Question 9

Ddx of transient synovitis:

Answer 9

• Septic arthritis o hip joint - HIGH FEVER, child LOOKS ILL, hip held flexed and severe pain at rest.

Question 10

Diagnosis of transient synovitis?

Answer 10

1) Mild to moderate restriction of internal hip rotation

2) Painless arc of motion

Question 11

Treatment of transient synovitis? Prognosis?

Answer 11

1) Bed rest
2) NSAID: ibuprofen

Symptom resolution in 1 week, in small proportion transient synovitis will precede Perthes disease.

Question 12

What is Reactive Arthritis? Ex and Ax?

Answer 12

• Sterile inflammation of the synovial membrane (synovitis), tendons and fascia triggered by an infection at a distant site (usually GI or genital).
  Ex: Most common arthritis in childhood
  Ax: Enteric bacteria - Salmonella, shigella, campylobacter. Or Viral infections.

Question 13

Presentation of Reactive arthritis?

Answer 13

Sx:

1) Transient joint swelling - ankles and knees (for less than 6 weeks)
2) Low grade fever

Dx:

1) Raised ESR, CRP (or normal)
2) X-ray: Normal

Question 14

Treatment of Reactive arthritis?

Answer 14

1) Supportive, and NSAIDs (ibuprofen)

Question 15

Septic Arthritis Ex and Ax?

Answer 15

Serious infection of the joint space that can lead to bone destruction, most common in children <2yrs.
Direct inoculation from trauma/surgery, haematogenous siding, extension from adjacent bone (osteomyelitis).

Ax:

1) Steph Aureus (most common)
2) Group B Streptococcus (Neonates)
3) Neisseria gonorrhoea (adolescents) (multiple joint)
4) Haemophilus influenzae (multiprofissional joint but rare)

Question 16

Risk factors of Septic Arthritis?

Answer 16

1) Immunodeficiency
2) Prematurity
3) Sickle cell disease
4) Osteomyelitis - can spread to cause septic arthritis

Question 17

Presentation of Septic arthritis? Ddx with transient synovitis?

Answer 17

1) Acute onset, usually one joint affected
2) Erythematous, warm, acutely tender joint
3) Reduced range of movement
4) Refusal to weight bear on affected side
5) Acutely unwell, with high fever (>38.5)
7) Guarding of limb and crying if moved
6) Diagnosis of hip is difficult - well covered by subcut fat (limp/pain referred to knee signs)

Ddx: Transient synovitis: Child looks well, with no/mild fever, no pain on rest only on movement, limited internal rotation.

Question 18

Diagnosis of Septic arthritis?

Answer 18

1) WBC, ESR, CRP raised
2) Blood cultures
3) Ultrasound to identify effusion
4) X-ray - widening of joint space?
5) Aspiration of joint space under US guidance - DIAGNOSTIC for culture
6) Kocher criteria

Question 19

Kocher criteria for Septic arthritis?

Answer 19

1) WCC>12000
2) Fever - >38.5
3) ESR >40
4) Inability to weight bear on affected side

3/4 - 93% chance of septic arthritis

Question 20

Treatment for Septic arthritis?

Answer 20

1) Joint washout/drainage may be required if slow resolution/deep-seated joint (e.g. hip)
2) Prolonged antibiotic course for 6 weeks: IV Vancomycin (Staph), OR IV Cefotaxime (Strep) - step down to oral after 2 weeks.
3) After initial immobilisation, ensure joint is mobilised to prevent permanent deformity.

Question 21

Complications of Septic arthritis?

Answer 21

1) Deformity
2) Limb length discrepancy - gait abnormalities
3) Femoral head destruction