We see both spellings in our industry.
In general...
Orthopedic is the preferred American English spelling.
Orthopaedic is the standard British English spelling.
The Origin
The word “Orthopaedics” comes from the Greek words “orthos” – meaning straight – and “paideion” – meaning children... or Straight Child. It was coined by French physician Nicholas Andry when he published Orthopaedia: or the Art of Correcting and Preventing Deformities in Children in 1741.
As with many words derived with the "æ" ligature, simplification to either "ae" or just "e" is common, especiall...