Abstract
Cementless stem fixation is a widely used method of stem revision in North America and elsewhere in the world. There is abundant literature in its support. Most of the reports from 1985 to 2005 related to proximally or extensively porocoated designs, the former falling into disfavor with time because of unpredictable outcomes. With few exceptions (e.g. S-ROM) the modularity of these designs was limited to the head/neck junction. But this generation of designs was associated with some issues such as insertional fractures, limited control of anteversion (and risk of dislocation), limited applicability in the setting of severe bone loss (Paprosky Type 4 osteolysis or Vancouver Type B3 periprosthetic fracture), as well as ongoing concern relating to severe proximal stress shielding.
In the past decade we have seen the mounting use of a new design concept: tapered fluted titanium stems (TFTS), which incorporate the advantages of titanium (for less flexural rigidity), conical taper (for vertical taper-lock stability), longitudinal ribs or flutes (for rotational stability), and surface preparation which attracts bone ongrowth for long term fixation.
Four consecutive reports from our center have documented the superiority of the TFTS in our hands, with encouraging outcomes even when dealing with severe bone loss or periprosthetic fractures. There is an increasing body of other literature which reports a similar experience.
Furthermore, with increasing experience and confidence in this design concept, we now use a monoblock or non-modular design in the majority of cases in which a TFTS is indicated. This circumvents the potential drawbacks of stem modularity, including taper corrosion and taper junction fracture. Our recent report of this concept in 104 cases with a 2-year minimum follow-up supports the use of this concept in many if not most stem revisions.
The question remains as to which should be favored? Because of equipoise in the outcomes of the two fundamental stem designs, at least in our hands, clearly the surgeon needs to ask other, more practical questions:
Am I familiar enough with the TFTS technique so as to bypass the potential versatility of the modular stem for the simplicity and potential cost savings of the non-modular?
Is this a case in which modularity will offer me distinct advantages (periprosthetic fracture, and severe bone loss as examples)
Should I introduce the nonmodular TFTS to my practice, choosing straightforward cases first; ones in which I would comfortably and with confidence use an extensively porocoated stem?
