Rickets

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Rickets, less commonly known as rachitis, refers to osteomalacia in the paediatric population that occurs before fusion of the growth plate.

Epidemiology

Rickets is seen in a number of distinct populations which include ⁴:

premature infants (especially if on parenteral nutrition)
unbalanced infant nutrition
- protracted exclusive breastfeeding
- non-vitamin D supplemented formula fed infants
- vegetarian diets
maternal vitamin D deficiency
lack of sun exposure
- dark skin in sun-poor countries
- lack of outdoor time
- clothing that eliminates sun exposure

The onset and presentation of rickets depend on the aetiology and degree of deficiency. Typically, in severe cases, rickets becomes apparent in the second year of life.

Clinical presentation

The presentation is usually with skeletal changes (see below) and bone pain.

Pathology

Results from abnormality or deficiency in one or more of ¹:

1,25-dihydroxyvitamin D
calcium
phosphorus, e.g. from X-linked hypophosphataemia
alkaline phosphatase
body pH

As a consequence of this imbalance, the ratio of mineralised to non-mineralised osteoid is abnormal (with an excess of the non-mineralised osteoid), and bone strength is reduced.

Varieties of rickets

vitamin D resistant rickets
vitamin D dependent
tumour-induced oncogenic rickets ⁶

Radiographic features

In the growing skeleton, the deficiency of normal mineralisation is most evident at metaphyseal zones of provisional calcification where there is an excess of non-mineralised osteoid resulting in growth plate widening with metaphysis flares out and appears frayed.

fraying; indistinct margins of the metaphysis
splaying; Widening of metaphyseal ends
cupping; Concavity of metaphysis ⁶

It is not surprising that these features are most prominent at the growth plates where growth is greatest:

knee: distal femur, proximal tibia
wrist: especially the ulna ¹
anterior rib ends: rachitic rosary

It is important to remember that even bones that appear mineralised are weak and result in bowing, most commonly seen in the lower limbs once the child is walking. The legs bow outwards with variable deformity of the hips (both coxa vara and coxa valga are seen ¹). Other bone deformities are also noted such as genu valga and vara as well as protrusio acetabuli. ⁶ The lower ribs may also be drawn inwards inferiorly by the attachment of the diaphragm (Harrison's sulcus).

A mnemonic to help remember these features is RICKETS.

Treatment and prognosis

Treatment requires correction of the metabolic imbalance. Only rarely is orthopaedic surgical intervention necessary to correct skeletal deformities.

Post-treatment

Radiographic features of rickets lag behind biochemical and clinical improvements about 2 weeks. Harris growth arrest line is a dense line traversing adjacent to metaphysis which can be used as a marker of old rickets. ⁶

Differential diagnosis

The differential for leg bowing in children includes ²:

developmental or congenital bowing
Blount disease
osteogenesis imperfecta
many others that are not usually a consideration (see leg bowing in children)

The differential for widening of the growth plate includes:

Schmid-type metaphyseal chondrodysplasia
hypovitaminosis C (scurvy)
delayed maturation due to illness
endocrine disturbances
- growth hormone excess
- hyperparathyroidism
- hypothyroidism

The differential for flaring of the metaphysis includes:

-</ul><p>As a consequence of this imbalance, the ratio of mineralised to non-mineralised osteoid is abnormal (with an excess of the non-mineralised osteoid), and bone strength is reduced.</p><p> </p><h5>Varieties of rickets</h5><ul>
+</ul><p>As a consequence of this imbalance, the ratio of mineralised to non-mineralised osteoid is abnormal (with an excess of the non-mineralised osteoid), and bone strength is reduced.</p><h5>Varieties of rickets</h5><ul>
-</ul><p>It is important to remember that even bones that appear mineralised are weak and result in bowing, most commonly seen in the lower limbs once the child is walking. The legs bow outwards with variable deformity of the hips (both <a href="/articles/coxa-vara">coxa vara</a> and <a href="/articles/coxa-valga-">coxa valga</a> are seen <sup>1</sup>). Other bone deformities are also noted such as genu valga and vara as well as <a href="/articles/protrusio-acetabuli-1">protrusio acetabuli</a>. <sup>6</sup> The lower ribs may also be drawn inwards inferiorly by the attachment of the diaphragm (<a href="/articles/harrison-s-sulcus">Harrison's sulcus</a>).</p><p>A mnemonic to help remember these features is <a href="/articles/rickets-mnemonic">RICKETS</a>.</p><h4>Treatment and prognosis</h4><p>Treatment requires correction of the metabolic imbalance. Only rarely is orthopaedic surgical intervention necessary to correct skeletal deformities.</p><p> </p><h5>Post-treatment</h5><p>Radiographic features of rickets lag behind biochemical and clinical improvements about 2 weeks. Harris growth arrest line is a dense line traversing adjacent to metaphysis which can be used as a marker of old rickets. <sup>6</sup></p><h4>Differential diagnosis</h4><p>The differential for <strong>leg bowing in children</strong> includes <sup>2</sup>:</p><ul>
+</ul><p>It is important to remember that even bones that appear mineralised are weak and result in bowing, most commonly seen in the lower limbs once the child is walking. The legs bow outwards with variable deformity of the hips (both <a href="/articles/coxa-vara">coxa vara</a> and <a href="/articles/coxa-valga-">coxa valga</a> are seen <sup>1</sup>). Other bone deformities are also noted such as genu valga and vara as well as <a href="/articles/protrusio-acetabuli-1">protrusio acetabuli</a>. <sup>6</sup> The lower ribs may also be drawn inwards inferiorly by the attachment of the diaphragm (<a href="/articles/harrison-s-sulcus">Harrison's sulcus</a>).</p><p>A mnemonic to help remember these features is <a href="/articles/rickets-mnemonic">RICKETS</a>.</p><h4>Treatment and prognosis</h4><p>Treatment requires correction of the metabolic imbalance. Only rarely is orthopaedic surgical intervention necessary to correct skeletal deformities.</p><h5>Post-treatment</h5><p>Radiographic features of rickets lag behind biochemical and clinical improvements about 2 weeks. Harris growth arrest line is a dense line traversing adjacent to metaphysis which can be used as a marker of old rickets. <sup>6</sup></p><h4>Differential diagnosis</h4><p>The differential for <strong>leg bowing in children</strong> includes <sup>2</sup>:</p><ul>