The Hip - book
Home » Joints » Hip » Radiographic Templating of Femoral Neck Length:

Radiographic Templating of Femoral Neck Length:

- See:
    - Technique of Femoral Neck Resection
    - Femoral Component Offset

- Discussion:
    - some pts have relative coxa vara and a very short distance between the lesser trochanter and the pelvis;
    - others have a relative coxa valga and a large distance between the lesser trochanter and pelvis;
    - select neck length to restore limb length and medial offset;
    - if no shortening is present, then match center of head w/ the previously marked center of the acetabulum;
    - if discrepancy exists, distance between femoral head center & acetabular center should be = to the previously measured limb length discrepancy;
    - once neck length is selected, mark level of anticipated neck resection and measure the distance from the top of lesser trochanter to use as an intra operative reference;
    - femoral head center frequently, but not always, corresponds w/ level of most superior aspect of greater trochanter;
    - aligning marking for neck length determined by preoperative x-rays analysis w/ level of center of femoral head will set neck resection guide at appropriate level;
    - incorrect neck resection level will be misleading w/ respect to apparent stem fit;
    - too high resection: - resection level which is too high, would yeild excessive space medially in proximal canal, leading one to believe stem is to small;
          - this would lead to varus stem position and high placement of head;
    - too low resection:
          - a resection level which is too low would result in impression that the stem is too large;
          - causes incomplete seating, valgus stem position, and low head placement