Description of device

Femoral stem medical devices are implanted into a patient’s thigh bone. They are classified as a type 3 medical device in the EU and are typically made from metal or metal alloys that may be surface treated. They can remain in place for a patient’s lifetime. A patient may have two implants at any given time. Over 90,000 were sold in the UK in 2017.

Specific Sample Related Considerations for Chemical Characterisation

  • Material of Construction: metal material – less extractable and no chance of solvent penetration to the material (extraction is a surface phenomenon)
  • Analytical Limits: very low due to large surface area, therefore a large amount of sample concentration is required
  • Extraction Type: exhaustive extraction which can further affect analytical limits and requires additional time and testing
  • Overall chemical characterisation complexity rating = 7

Numbers sold per year (UK) 91,698
Contact time Patient life time
Patient contact devices/day 2
Analytical Limits (without concentration) 0.00075
Study Complexity (out of 10) 7


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Key Factors for Chemical Characterisation

  • Related Guideline – 10993-18
  • Extraction Type – Exhaustive (due to long term, >30 days contact)
  • Solvents – 3 (polar, semi-polar, non-polar)
  • Typical Sample Size – Very Large (200cm2)
  • Extraction volume 200 mL
  • Analytical Limits (without concentration) = 0.00075 ug/mL