Abstract
The author's experience is with a specific type of femoral stem and modular neck both fabricated from Ti alloy. Fracture of this Ti-Ti modular neck is associated with heavy weight, heavy activity, long modular necks and corrosion at the junction of the neck to the stem. Instruments have been designed that can remove the distal fragment of the fractured modular neck in most cases.
After the neck is removed, the clinician is faced with the decision to remove the stem or to place another modular neck. At present MicroPort (formerly Wright Medical Technology) the company whose modular neck forms the data for this presentation, suggests that the female part of the taper (that is the part at the top of the stem) should not be reused if a modular neck (fractured or intact) has been removed. Thus the recommendation from the company is that the stem be removed. This recommendation is true across all modular neck – femoral stem combinations particularly for those that have been recalled by the manufacturer.
There is no question that the female taper is changed by having had the modular neck implanted. In most cases of fracture there is severe corrosion at the junction of the neck to stem. Thus, reuse of the taper could have problems and it is understandable that the company does not sanction its reuse. On the other hand, removal of a well-fixed ingrown stem is not without morbidity. In several cases, with patient informed consent, I have left the stem and implanted a new modular neck (either CoCr or Ti alloy) in the damaged taper. We are following these patients closely and it is too soon to make recommendations as to the wisdom of this practice.
My strong recommendation is to remove the stem and place a new one.
