A 6-year-old boy fell down and injured Left wrist joint, operated and plastered four months ago. After removing plaster, hand looks like wrist drop. He can move wrist joint but not full range of movements, at rest it remains in condition of wrist drop. MT cbc esr, MRI of wrist is normal, usg of wrist TB?

X-ray wrist done every month is normal. This child was referred to me to ruleuot TB in joint, I couldn't detect tb. What happened during operatives procedure /or nerve injury missed initially?