Total Hip Revision Arthroplasty Techniques - Uncemented Revision Options
Proximally porous coated
Be wary as:
- These obtain fixation by “fit and fill” in the metaphysis and in revision setting it is often the metaphysis which is deficient.
- The cylindrical stem often provides little torsional stability unless they have deep cutting flutes (such as the SROM).
- The stems are often straight and in the revision setting a long stem is frequently needed – be aware of the anatomic bow of the femur and that the long straight stem can be accommodated.
- Bridging of bony defects with long, proximally coated stems will provide limited distal stability
Fully porous coated – Best results (approaching primary stems – 3-7% failure at 13 years).
Often a better option due to the following:
- They obtain their fixation in the diaphysis (where the bone is generally good) – bypassing the deficient metaphyseal bone.
- Less anatomic variation in the diaphysis as compared to the metaphysis allows for more reliable fill.
Success is correlated with:
- Canal fill > 90%.
- Diaphyseal support of > 4-6cm.
- Satisfy these criteria and the success approaches primary stems.
- Problems with this technique (both relate to difficulty of any further surgery) and proximal stress shielding.
- This is made worse by the fact that thus far these stems are only available in Co Cr. Due to its stiff modulus, Co Cr stems bigger than 13.5mm and are associated with stress shielding.
- There is difficulty in removing an ingrown fully porous stem.