Rickets
Updates to Article Attributes
Rickets, less commonly known as rachitis, refers to deficient mineralizationmineralisation of the growth plate in the paediatric population. In contrast, osteomalacia refers to deficient mineralizationmineralisation of the bone matrix, which co-occurs with rickets but can also occur even after growth plate closure, in adults 7.
Epidemiology
Risk factors
Rickets is seen in a number of distinct populations 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
Aetiology
Abnormalities in calcium-phosphate homeostasishomoeostasis disrupt endochondral ossification at open physes. The etiologiesaetiologies can be classified by whether the initial abnormality is inadequate calcium absorption or excessive phosphate excretion, termed "calcipenic" and "phosphopenic" rickets, respectively 7,8. The serum laboratory abnormalities are characteristic:
-
calcipenic rickets
parathyroid hormone: markedly elevated
calcium: low or normal
phosphate: low or normal
-
phosphopenic rickets
parathyroid hormone: normal or modestly elevated
calcium: normal
phosphate: low
Calcipenic rickets etiologiesaetiologies are the most common:
vitamin D deficiency (most common cause) due to diet, insufficient sun exposure, and/or malabsorption
dietary calcium deficiency
defective vitamin D metabolism: mutation in CYP27B1 gene, which encodes the renal 1-alpha-hydroxylase enzyme (vitamin D dependent rickets type 1); 25-hydroxylase deficiency (very rare)
hereditary vitamin D resistance: mutation in VDR gene, which encodes the vitamin D receptor (vitamin D dependent rickets type 2)
Phosphopenic rickets etiologiesaetiologies are usually associated with elevated circulating fibroblast growth factor 23 (FGF23) levels and/or renal tubule disorders:
hereditary
hypophosphatemichypophosphataemic rickets (vitamin D resistant rickets)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 and abnormal configuration of the metaphysis:
fraying: indistinct margins of the metaphysis
splaying: widening of metaphyseal ends
cupping: concavity of metaphysis 6
Pseduofracture on the compression side of bone known as Looser's zone.
It is not surprising that these features are most prominent at the bones where growth is greatest:
knee: distal femur, proximal tibia
wrist: especially the ulna 1
-
anterior rib ends: rachitic rosary
As osteomalacia co-occurs with rickets, 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). Presence of Codfish vertebrae is another Radiographic feature of rickets.
A mnemonic to help remember these features is RICKETS.
Post-treatment radiographic appearances
Radiographic features of rickets lag behind biochemical and clinical improvements by about 2 weeks. Harris growth arrest line is a dense line traversing parallel to the metaphysis which can be used as a marker of old rickets 6.
Treatment and prognosis
Treatment requires correction of the metabolic imbalance. Only rarely is the orthopaedic surgical intervention necessary to correct skeletal deformities.
Differential diagnosis
The differential for leg bowing in children includes 2:
developmental or congenital bowing
many others that are not usually a consideration (see leg bowing in children)
The differential for a widening of the growth plate includes:
Schmid-type metaphyseal chondrodysplasia
delayed maturation due to illness
-
endocrine disturbances
growth hormone excess
The differential for flaring of the metaphysis includes:
storage diseases
chronic lead poisoning
-<p><strong>Rickets</strong>, less commonly known as <strong>rachitis</strong>, refers to deficient mineralization of the growth plate in the paediatric population. In contrast, <a href="/articles/osteomalacia">osteomalacia</a> refers to deficient mineralization of the bone matrix, which co-occurs with rickets but can also occur even after growth plate closure, in adults <sup>7</sup>.</p><h4>Epidemiology</h4><h5>Risk factors</h5><p>Rickets is seen in a number of distinct populations <sup>4 </sup>:</p><ul>-<li>premature infants (especially if on parenteral nutrition)</li>-<li>unbalanced infant nutrition<ul>-<li>protracted exclusive breastfeeding</li>-<li>non-vitamin D supplemented formula-fed infants</li>-<li>vegetarian diets</li>-</ul>-</li>-<li>maternal <a href="/articles/vitamin-d">vitamin D</a> deficiency</li>-<li>lack of sun exposure<ul>-<li>dark skin in sun-poor countries</li>-<li>lack of outdoor time</li>-<li>clothing that eliminates sun exposure</li>- +<p><strong>Rickets</strong>, less commonly known as <strong>rachitis</strong>, refers to deficient mineralisation of the growth plate in the paediatric population. In contrast, <a href="/articles/osteomalacia">osteomalacia</a> refers to deficient mineralisation of the bone matrix, which co-occurs with rickets but can also occur even after growth plate closure, in adults <sup>7</sup>.</p><h4>Epidemiology</h4><h5>Risk factors</h5><p>Rickets is seen in a number of distinct populations <sup>4 </sup>:</p><ul>
- +<li><p>premature infants (especially if on parenteral nutrition)</p></li>
- +<li>
- +<p>unbalanced infant nutrition</p>
- +<ul>
- +<li><p>protracted exclusive breastfeeding</p></li>
- +<li><p>non-vitamin D supplemented formula-fed infants</p></li>
- +<li><p>vegetarian diets</p></li>
-</ul><p>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.</p><h4>Clinical presentation</h4><p>The presentation is usually with skeletal changes (see below) and bone pain.</p><h4>Pathology</h4><h5>Aetiology</h5><p>Abnormalities in calcium-phosphate homeostasis disrupt endochondral ossification at open <a href="/articles/physis">physes</a>. The etiologies can be classified by whether the initial abnormality is inadequate calcium absorption or excessive phosphate excretion, termed "calcipenic" and "phosphopenic" rickets, respectively <sup>7,8</sup>. The serum laboratory abnormalities are characteristic:</p><ul>-<li>calcipenic rickets<ul>-<li>parathyroid hormone: markedly elevated</li>-<li>calcium: low or normal</li>-<li>phosphate: low or normal</li>- +<li><p>maternal <a href="/articles/vitamin-d">vitamin D</a> deficiency</p></li>
- +<li>
- +<p>lack of sun exposure</p>
- +<ul>
- +<li><p>dark skin in sun-poor countries</p></li>
- +<li><p>lack of outdoor time</p></li>
- +<li><p>clothing that eliminates sun exposure</p></li>
-<li>phosphopenic rickets<ul>-<li>parathyroid hormone: normal or modestly elevated</li>-<li>calcium: normal</li>-<li>phosphate: low</li>- +</ul><p>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.</p><h4>Clinical presentation</h4><p>The presentation is usually with skeletal changes (see below) and bone pain.</p><h4>Pathology</h4><h5>Aetiology</h5><p>Abnormalities in calcium-phosphate homoeostasis disrupt endochondral ossification at open <a href="/articles/physis">physes</a>. The aetiologies can be classified by whether the initial abnormality is inadequate calcium absorption or excessive phosphate excretion, termed "calcipenic" and "phosphopenic" rickets, respectively <sup>7,8</sup>. The serum laboratory abnormalities are characteristic:</p><ul>
- +<li>
- +<p>calcipenic rickets</p>
- +<ul>
- +<li><p>parathyroid hormone: markedly elevated</p></li>
- +<li><p>calcium: low or normal</p></li>
- +<li><p>phosphate: low or normal</p></li>
-</ul><p>Calcipenic rickets etiologies are the most common:</p><ul>-<li>-<a title="Vitamin D deficiency (overview)" href="/articles/vitamin-d-deficiency-overview">vitamin D deficiency</a> (most common cause) due to diet, insufficient sun exposure, and/or malabsorption</li>-<li>dietary calcium deficiency</li>-<li>defective vitamin D metabolism: mutation in <em>CYP27B1 </em>gene, which encodes the renal 1-alpha-hydroxylase enzyme (vitamin D dependent rickets type 1); 25-hydroxylase deficiency (very rare)</li>-<li>hereditary vitamin D resistance: mutation in <em>VDR </em>gene, which encodes the vitamin D receptor (vitamin D dependent rickets type 2)</li>-</ul><p>Phosphopenic rickets etiologies are usually associated with elevated circulating fibroblast growth factor 23 (FGF23) levels and/or renal tubule disorders:</p><ul>-<a href="/articles/hereditary-hypophosphatemic-rickets">hereditary hypophosphatemic rickets</a> (vitamin D resistant rickets)</li>-<li>tumour-induced (oncogenic) rickets <sup>6</sup>- +<p>phosphopenic rickets</p>
- +<ul>
- +<li><p>parathyroid hormone: normal or modestly elevated</p></li>
- +<li><p>calcium: normal</p></li>
- +<li><p>phosphate: low</p></li>
- +</ul>
-<li><a href="/articles/fanconi-syndrome">Fanconi syndrome</a></li>- +</ul><p>Calcipenic rickets aetiologies are the most common:</p><ul>
- +<li><p><a href="/articles/vitamin-d-deficiency-overview" title="Vitamin D deficiency (overview)">vitamin D deficiency</a> (most common cause) due to diet, insufficient sun exposure, and/or malabsorption</p></li>
- +<li><p>dietary calcium deficiency</p></li>
- +<li><p>defective vitamin D metabolism: mutation in <em>CYP27B1 </em>gene, which encodes the renal 1-alpha-hydroxylase enzyme (vitamin D dependent rickets type 1); 25-hydroxylase deficiency (very rare)</p></li>
- +<li><p>hereditary vitamin D resistance: mutation in <em>VDR </em>gene, which encodes the vitamin D receptor (vitamin D dependent rickets type 2)</p></li>
- +</ul><p>Phosphopenic rickets aetiologies are usually associated with elevated circulating fibroblast growth factor 23 (FGF23) levels and/or renal tubule disorders:</p><ul>
- +<li><p><a href="/articles/hereditary-hypophosphatemic-rickets">hereditary hypophosphataemic rickets</a> (vitamin D resistant rickets)</p></li>
- +<li><p>tumour-induced (oncogenic) rickets <sup>6</sup></p></li>
- +<li><p><a href="/articles/fanconi-syndrome">Fanconi syndrome</a></p></li>
-<li>fraying: indistinct margins of the metaphysis</li>-<li>splaying: widening of metaphyseal ends</li>-<li>cupping: concavity of metaphysis <sup>6</sup>-</li>- +<li><p>fraying: indistinct margins of the metaphysis</p></li>
- +<li><p>splaying: widening of metaphyseal ends</p></li>
- +<li><p>cupping: concavity of metaphysis <sup>6</sup></p></li>
- +<li><p>Pseduofracture on the compression side of bone known as Looser's zone. </p></li>
-<li>knee: distal femur, proximal tibia</li>-<li>wrist: especially the ulna <sup>1</sup>-</li>-<li>anterior rib ends: <a href="/articles/rachitic-rosary">rachitic rosary</a>-</li>-</ul><p>As osteomalacia co-occurs with rickets, 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/acetabular-protrusion-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-sulcus">Harrison's sulcus</a>).</p><p>A mnemonic to help remember these features is <a href="/articles/rickets-mnemonic">RICKETS</a>.</p><h5>Post-treatment radiographic appearances</h5><p>Radiographic features of rickets lag behind biochemical and clinical improvements by about 2 weeks. <a href="/articles/growth-arrest-lines">Harris growth arrest line</a> is a dense line traversing parallel to the metaphysis which can be used as a marker of old rickets <sup>6</sup>.</p><h4>Treatment and prognosis</h4><p>Treatment requires correction of the metabolic imbalance. Only rarely is the orthopaedic surgical intervention necessary to correct skeletal deformities.</p><h4>Differential diagnosis</h4><p>The differential for <a href="/articles/leg-bowing-in-children">leg bowing in children</a> includes <sup>2</sup>:</p><ul>-<li>developmental or <a href="/articles/congenital-leg-bowing">congenital bowing</a>-</li>-<li><a href="/articles/blount-disease">Blount disease</a></li>-<li><a href="/articles/osteogenesis-imperfecta-1">osteogenesis imperfecta</a></li>-<li>many others that are not usually a consideration (see <a href="/articles/leg-bowing-in-children">leg bowing in children</a>)</li>- +<li><p>knee: distal femur, proximal tibia</p></li>
- +<li><p>wrist: especially the ulna <sup>1</sup></p></li>
- +<li>
- +<p>anterior rib ends: <a href="/articles/rachitic-rosary">rachitic rosary</a></p>
- +<p></p>
- +<p></p>
- +</li>
- +</ul><p>As osteomalacia co-occurs with rickets, 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/acetabular-protrusion-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-sulcus">Harrison's sulcus</a>). Presence of Codfish vertebrae is another Radiographic feature of rickets. </p><p>A mnemonic to help remember these features is <a href="/articles/rickets-mnemonic">RICKETS</a>.</p><h5>Post-treatment radiographic appearances</h5><p>Radiographic features of rickets lag behind biochemical and clinical improvements by about 2 weeks. <a href="/articles/growth-arrest-lines">Harris growth arrest line</a> is a dense line traversing parallel to the metaphysis which can be used as a marker of old rickets <sup>6</sup>.</p><h4>Treatment and prognosis</h4><p>Treatment requires correction of the metabolic imbalance. Only rarely is the orthopaedic surgical intervention necessary to correct skeletal deformities.</p><h4>Differential diagnosis</h4><p>The differential for <a href="/articles/leg-bowing-in-children">leg bowing in children</a> includes <sup>2</sup>:</p><ul>
- +<li><p>developmental or <a href="/articles/congenital-leg-bowing">congenital bowing</a></p></li>
- +<li><p><a href="/articles/blount-disease">Blount disease</a></p></li>
- +<li><p><a href="/articles/osteogenesis-imperfecta-1">osteogenesis imperfecta</a></p></li>
- +<li><p>many others that are not usually a consideration (see <a href="/articles/leg-bowing-in-children">leg bowing in children</a>)</p></li>
-<li>Schmid-type <a href="/articles/metaphyseal-chondrodysplasia">metaphyseal chondrodysplasia</a>-</li>-<li><a href="/articles/hypovitaminosis-c-scurvy-1">hypovitaminosis C (scurvy)</a></li>-<li>delayed maturation due to illness</li>-<li>endocrine disturbances<ul>-<li>growth hormone excess</li>-<li><a href="/articles/hyperparathyroidism">hyperparathyroidism</a></li>-<li><a href="/articles/hypothyroidism">hypothyroidism</a></li>- +<li><p>Schmid-type <a href="/articles/metaphyseal-chondrodysplasia">metaphyseal chondrodysplasia</a></p></li>
- +<li><p><a href="/articles/hypovitaminosis-c-scurvy-1">hypovitaminosis C (scurvy)</a></p></li>
- +<li><p>delayed maturation due to illness</p></li>
- +<li>
- +<p>endocrine disturbances</p>
- +<ul>
- +<li><p>growth hormone excess</p></li>
- +<li><p><a href="/articles/hyperparathyroidism">hyperparathyroidism</a></p></li>
- +<li><p><a href="/articles/hypothyroidism">hypothyroidism</a></p></li>
-<li><a href="/articles/anaemia">anaemias</a></li>-<li><a href="/articles/fibrous-dysplasia">fibrous dysplasia</a></li>-<li>storage diseases</li>-<li>chronic <a href="/articles/lead-poisoning-1">lead poisoning</a>-</li>-<li><a href="/articles/skeletal-dysplasia">bone dysplasias</a></li>- +<li><p><a href="/articles/anaemia">anaemias</a></p></li>
- +<li><p><a href="/articles/fibrous-dysplasia">fibrous dysplasia</a></p></li>
- +<li><p>storage diseases</p></li>
- +<li><p>chronic <a href="/articles/lead-poisoning-1">lead poisoning</a></p></li>
- +<li><p><a href="/articles/skeletal-dysplasia">bone dysplasias</a></p></li>
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