The External Obturator Footprint as a Landmark for Stem Depth in Direct Anterior Total Hip Arthroplasty - Clinical Validation
The External Obturator Footprint as a Landmark for Stem Depth in Direct Anterior Total Hip Arthroplasty - Clinical Validation
One of the goals of Total Hip Arthroplasty (THA) is to reconstruct leg length as adequately
 as possible. In order to achieve this one needs landmarks that are visible both on the
 templating X ray as well as during surgery. The classical posterior and lateral approaches
 often rely on the distance from the greater trochanter (GT) to the shoulder of the femoral
 stem or the distance from the lesser trochanter (LT) to the side of the neck osteotomy. If
 the surgeon finds out on the digital template that the distance from the GT to the shoulder
 of the implant should be X mm to achieve equal leg length, than the surgeon can try to
 reconstruct this during surgery. During the Direct Anterior Approach (DAA) these landmarks
 usually are not visible or require additional dissection injuring important soft tissue
 structures along the way. One anatomical structure that appears to be always visible during
 the DAA is the External Obturator tendon (EO). It was recently confirmed that the level of
 insertion of the EO onto the proximal femur can also always be determined on pre-operative X
 rays. It therefore represents one of the few landmarks that is visible both on the templating
 X ray as well as during DAA THA. Indeed, many hip surgeons, including ourselves, believe that
 if the shoulder of the femoral stem is near the insertion of the EO leg length cannot be far
 off. However, there is no clinical data to support this. The investigators would therefore
 like to the correlate the distance observed intra-operatively to the actual established
 distance on the post-operative X ray.
Inclusion Criteria:

 -  All patient who underwent THA via DAA by a single surgeon who routinely documents the
 distance from the shoulder of the stem to the upper border of the EO tendon

 Exclusion Criteria:

 -  Distance not noted

 -  No radiographs available