A 2-year-old boy, fifth child in a caucasian family of political refugees, was referred to the pediatrician for further investigation of a windswept deformity and of a deflection in the length and weight grow curve.
The boy was breastfed exclusively for the first 4 months, and received breastfeeding in combination with solids through the first and second year. Supplements of vitamin D were advised but neglected by the parents. Laboratory investigation revealed hypocalcaemia, increased parathyroid hormone levels, low phosphorus and increased alkaline phosphatase concentrations. Radiographs of the legs demostrated the clinically diagnosed windswept deformity. Radiographs of the wrist and knees showed metaphyseal cupping, fraying and irregularity along the physeal margins. The chest radiograph revealed discrete widening of the sternal ends of the ribs. The diagnosis of (nutritional) rickets was made and therapy with vitamin D supplements was initiated. Laboratory values and radiographic findings were normal on follow-up examination three months after initiation of therapy.
Rickets is the bony manifestation of a (relative or absolute) deficiency of vitamin D or its derivatives, which can result from dietary deficiency, malabsorption, renal disease, or lack of end-organ response. Most cases of nutritional rickets in Europe and in the United States occur in breastfed infants who receive no vitamin D supplementation. The lack of vitamin D results in insufficient conversion of growing cartilage into mineralized osteoid and build-up of non-ossified osteoid, resulting in growth retardation and delayed skeletal development. Rickets refers to the changes caused by deficient mineralization at the growth plate, while osteomalacia refers to impaired mineralization of the bone matrix. Rickets and osteomalacia usually occur together as long as the growth plates are open; only osteomalacia occurs after the growth plates have fused.
The radiographic findings of rickets are most prominent in rapidly growing bones, and skeletal surveys to evaluate for rickets can be confined to frontal views of the knees and wrists. Radiographic hallmarks include metaphyseal fraying, cupping, and irregularity along the physeal margin. The sternal ends of the ribs may enlarge and result in the appearance of a "rachitic rosary". Patients may be predisposed to insufficiency fractures (Looser zones) and slipped capital femoral epiphyses. Craniotabes may occur, in which the bones of the skull soften and flattening of the posterior skull can be seen. Weight bearing may result in an exaggeration of the normal physiological bowing of the legs (genu varum), which is a characteristic finding in the toddler who has started to walk. Development of knock-knees (genu valgum) may occur because of displacement of the growth plates during active disease. The combination of genu varum and genu valgum, as seen in our patient, is called windswept deformity. The type of deformity (valgus, varus, or windswept deformity) depends upon the biomechanical situation of the lower extremities at the time when the structural weakness develops.
Rickets
1. From the provided anteroposterior and lateral X-ray views of the lower limbs, the proximal tibial and distal femoral metaphyses bilaterally show characteristic “roughening” changes, including a blurred marrow-cortex interface, metaphyseal cupping, and irregular (fraying) edges.
2. Abnormal lower-limb alignment: on one side there is genu valgum (knock-knee), while the other side may show varying degrees of valgum or varum, resulting in a “windswept” knee deformity.
3. The hand X-ray also reveals similar poor calcification and fuzzy metaphyseal margins in areas of rapid growth, indicating severe impairment in bone mineralization.
4. A longitudinal review of the chest X-ray suggests a relatively normal thorax, but there is a suspicion of mild sternal or costochondral widening (a possible “rachitic rosary”), consistent with active rickets imaging features.
5. No definite fracture lines are observed. However, against a background of osteopenia, the risk of fractures is increased and warrants ongoing surveillance.
Based on the imaging findings, the child’s age, and nutritional and social background, the possible diagnoses or differential diagnoses include:
Considering the family background (potentially inadequate nutrition), clinical presentation (windswept deformity, deviation of height and weight growth curves), and radiographic features of the metaphyses, a preliminary diagnosis of vitamin D deficiency rickets (nutritional rickets) can be established.
1. Medication and Nutritional Supplementation:
- Provide adequate Vitamin D supplementation (dosage adjusted according to body weight and serum 25-hydroxyvitamin D levels, commonly 400–1000 IU/day, following pediatric nutrition guidelines).
- Ensure appropriate calcium intake and a balanced diet. If other nutrient deficiencies exist (e.g., iron or protein), these should be corrected accordingly.
- Regularly monitor serum calcium, phosphorus, and alkaline phosphatase, and follow up on bone development status.
2. Orthopedic Management and Exercise Training:
- Given fragile bones and lower-limb deformities, consider using soft braces or orthoses when necessary to maintain proper lower-limb alignment.
- Rehabilitation training should be gradual and individualized. For a 2-year-old child, activities can be integrated into daily routines:
3. Application of the FITT-VP Principle for This Child:
- Frequency: 3–5 times per week of regular rehabilitation activities, or incorporate daily play to ensure consistent weight-bearing stimulation.
- Intensity: Light to moderate, avoiding excessive load on vulnerable growth plates and soft bone areas under repair.
- Time: Start each session at 10–15 minutes. Based on tolerance and skeletal development, gradually extend to 20–30 minutes every 1–2 weeks.
- Type: Primarily safe, supervised standing, walking, and squatting weight-bearing activities, supplemented with outdoor sun exposure.
- Progression: As the child’s bone health and muscle strength improve, incrementally increase the duration and range of weight-bearing activities. Conduct regular follow-up to monitor improvement in lower-limb deformities.
- Volume: The overall activity volume should match the child’s growth status, with prompt adjustments if any adverse symptoms occur.
This report is based solely on the currently provided patient history and imaging data, and it does not replace an in-person clinical diagnosis and treatment recommendation. Specific treatment and rehabilitation plans should be conducted under the guidance of a qualified pediatrician or orthopedic specialist to ensure patient safety and efficacy.
Rickets
