TOACS FCPS Station · X‑ray Hip: Epiphyseal Dysgenesis (Congenital Hypothyroidism)

📷 X‑ray Hip (AP view)

Hip X-ray showing epiphyseal dysgenesis of the femoral head in congenital hypothyroidism

Figure 1 · AP hip radiograph · Congenital Hypothyroidism – Epiphyseal Dysgenesis

🔍 Key radiographic features:

✓ Delayed appearance of the femoral head epiphysis (absent or small)
✓ Fragmented, stippled appearance – multiple small ossification centers
✓ Irregular epiphyseal contour – “moth-eaten” appearance
✓ Widened joint space – due to delayed ossification
✓ Delayed bone age – overall skeletal maturation retarded

📋 Clinical scenario (examiner prompt)

A 9‑month‑old infant with known congenital hypothyroidism (diagnosed by newborn screening) presents for routine follow‑up. The infant has been on levothyroxine since day 14 of life but has had poor adherence to therapy. On examination, there is hypotonia, macroglossia, and delayed motor milestones. A hip X‑ray (AP view) is shown.

Congenital hypothyroidism Fragmented epiphysis Delayed bone age Poor adherence

🧑‍⚕️ Examiner tasks · TOACS

1. Identify the diagnosis from the hip X‑ray and clinical context.

2. Describe the X‑ray findings (epiphyseal dysgenesis, fragmented femoral head).

3. Explain the pathophysiology (thyroid hormone deficiency → impaired ossification).

4. Discuss management (levothyroxine adherence, monitoring, prognosis).

⚠️ Key concept: Epiphyseal dysgenesis is a classic skeletal finding in untreated or poorly treated congenital hypothyroidism. The femoral head epiphysis may be absent, fragmented, or stippled (multiple small ossification centers). This results from impaired endochondral ossification due to thyroid hormone deficiency. Delayed bone age is universal in untreated hypothyroidism.

🎯 Expected answers (for examiners)

• Diagnosis: Epiphyseal dysgenesis due to congenital hypothyroidism (poorly controlled)
• X‑ray findings: Fragmented/stippled femoral head epiphysis, delayed ossification, widened joint space
• Pathophysiology: Thyroid hormone deficiency → impaired chondrocyte maturation and endochondral ossification
• Management: Optimize levothyroxine dose (10-15 mcg/kg/day), ensure adherence, monitor TSH/free T4, repeat bone age

⚡ Quick FCPS‑style MCQ

A fragmented, stippled femoral head epiphysis on hip X‑ray in an infant with congenital hypothyroidism is due to:

A. Thyroid hormone deficiency → impaired endochondral ossification B. Growth hormone deficiency C. Vitamin D deficiency D. Osteomyelitis

Feature	Congenital Hypothyroidism
Bone age	Delayed (retarded skeletal maturation)
Epiphyses	Fragmented, stippled, absent (dysgenesis)
Skull	Wide sutures, large fontanels
Reversibility	Reversible with adequate levothyroxine

🩻 TOACS FCPS Station · X‑ray Hip: Epiphyseal Dysgenesis (Congenital Hypothyroidism)

📷 X‑ray Hip (AP view)

🧑‍⚕️ Examiner tasks · TOACS

📌 Topic summary ·