Ch Belli, P Bousquet, GP Muller – Papeete – Tahiti
With the world record of morbidly obese people, THA in Polynesia often poses installation problems and questions around the surgical approach. For our part, we operate using the Supine Position with some installation details that greatly simplify the operation but above all uses an original approach “self -separating”, this is the Orthodromic Approach that we have described.
After more than 800 THA all of which were in the Supine Postion, we have managed to develop a unique argument.
Our attitude is to consider in depth the Fascia Lata, there is no significant difference according to the patient’s weight.
The idea comes from the problem whereby access is through the “fat mass” which we sometimes see on particularly developed breeches although the BMI remains in the realm of reasonableness.
The approach must allow:
- An axis for the Acetabular Rim Cutter to descend slightly for an anteversion.
- An axis for the Femur Grinder to slightly ascend, especially as the femur has a large volume.
The distal extremity of the scar should be generally at the axis of the femur while the proximal end must be significantly lower.
The passage of fat must therefore join these two points bypassing a volume sometimes close to that of a sphere.
The solution is based on geometry and not on an anatomical reflection. The quickest way to connect the two points on a curved surface is Orthodromically.
The shape of the incision corresponding to the logical geometry is an arc whose concavity is directed downwards, a kind of Watson Jones reversed incision!
To get the Orthodromic outline, simply apply a cord (such as the anaesthetists
stethoscope) from the proximal point to the distal point. It will automatically take to the curvature of the shortest path. This curve determines an oblique sectional level to the inside and the lower end which allows us to globally reach the trochanteric mass in the axis of the femur.
The incision seen from the patient’s feet is on the right! The operator thus finds itself facing a hip that is no longer an obese hip (or almost) and for the continuation of the operation it is now possible to choose between all variants (Rothinger, Hardinge, other).
The lower lip of the incision falls under its own weight, the forward spacing is done without any effort and therefore without any threat to the femoral.
The other important elements of this installation in the Supine Position are:
- Hyper extension setting of the contralateral hip
- The maximum lateralization of the hip which is to be operated placing the ischium near the table edge
- A moderate Trendelbourg position for the lower limb to lean downwards in order to stem blood.
- Pull the abdominal area towards the healthy side
- A sturdy table, long instruments with a tip to extend the space.
The slide show presentation shows these various technical issues and in particular the tracing of the incision.
The installation in the Supine Position facilitates the finding of space among the obese (for positioning the Acetabulum in particular), it prevents the increase of bleeding and cuts the amount debris at the bottom of the Acetabulum, it is safer while under anaesthesia.
This approach, in addition to the operating comfort it provides, puts the scar free from maceration, ensures stability of the prosthesis which is significantly higher during flexion and doesn’t show any tension during this movement.
In conclusion during THA with obese patients the only problem which arises is how to access the mass of fat, this is now solved thanks to the use of geometry within the area.