Abstract
This study looks at Australian Orthopaedic Association National Joint Replacement Registry figures to try to see if any questions can be answered about the role of the trunion in some THR failures.
The Registry shows that large head (≥50 mm) hip resurfacings are doing well in appropriate patients, but the same size resurfacing cups with stemmed THR are doing poorly, while the smaller sizes in metal/metal stemmed THR continue to perform well.
The Registry also shows all stemmed THR with exchangeable (modular) necks have twice the revision rate of non exchangeable necks, and that these revisions are for dislocation as well as “loosening/lysis”.
One possible reason for the failure of large head metal – metal THRs is the trunion, which has been designed for use with small (22 mm–32 mm) femoral heads and is now being used with large (up to 56 mm) femoral heads.
We postulated that if the trunion were failing it might be seen more commonly with the smaller tapers such as the Stryker V40 taper, and that this might be seen with large (36 mm–44 mm) metal heads used on these tapers even in metal-poly hips.
Results from the Registry are shown.
