I prefer collared uncemented stem in revision hip arthroplasty cases only

I agree that collared stems have especially advantages in revision arthroplasty in

prevention of migration in the early post-operative period and improved load transfer to the calcar and successful osseointegration.

I agree! In revision settings collared stems seem to prevent migration compared with collarless stems.

So, in regular primary cases you don't use collared stems? In your opinion, does the shape of the femoral canal (Dorr types) have any influence on your decision?

Additionally, anatomy of the femoral canal shape (see Dorr classification) may dictate the use of uncemented vs cemented stem (not actually collared vs non-collared uncemented stems).

Don't you think that especially in Dorr Type A femurs a collar could give you additional support if you cannot reach optimal metaphyseal fit and fill? Or do you go straight to cemented stems? I am just asking because Dorr Type A is mostly seen in younger active patients and our institution tends to use uncemented stems in this group of patients.

I mostly use non-collar uncemented hip prostheses.

Collared uncemented stems have significantly greater immediate stability than collarless though the long term outcome might be the same

They are able to withstand greater multi-directional forces thereby ensuring less chances of implant subsidence and fracture

Hi, I don't use those stems, because I prefer to rely on wide stress distribution than local from the collar. I have seen periarticular ossification around the collar, probably because of irritation of iliopsoas tendon.

This is probably one of the biggest downsides that load and stress distribution might not be as "natural" as with collarless stems. However, a recent biomechanical study by Lamb et al. suggested that collared stems seem to prevent periprosthetic fractures occurred through torsional stress.

I tend to use non-collared uncemented stems though use collared one in elderly undergoing uncemeted hemiarthroplasty

I think collared cementless stem in primary hip can be used when surgeon concerned about inadequate vertical stability to prevent subsidence especially in fully coated cylindrical stem. For wedge type stem, if there is no metaphyseal diaphyseal mismatch , increase stem size to make stem adequately fit should be justified without the need of collar. I used collared stem only in revision case.

Ideally would like to always use a collar. The collar cannot substitute good primary fixation and cannot be seen as a tool to prevent subsidence in an undersized stem. The major advantage it imparts is the rotational stability , hence the ability to resist the high torsional forces on the stem-bone interface prior to biological fixation. It is the high torsional forces in those early stages which can lead to lack of fixation and loosening. This is important as patients tend to mobilise earlier and faster with modern rapid recovery protocols.

Another advantage is the ability to adjust the height of the stem using the collar depending on the proximal femoral anatomy.

In most of my cases I use a non-cemented stem without a collar, but I think that the use of the collar depends on the type of stem, if a wagner-type stem is used, the collar makes more sense than a wedge like the Corail where part of the success is the pressure fit when resting on the impacted spongy bone.

no advantages