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Subtrochanteric approach (according to Guardini)

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As with the anterior approach to the sciatic nerve, the subtrochanteric approach offers the advantage that it does not require painful repositioning of the patient, for example secondary to trauma or fractures. Another even greater advantage over the anterior approach, we believe, is the low puncture depth into the nerves and the fact that no vulnerable structures are located in or along the puncture channel.

 

Anatomical landmarks

Greater trochanter, ischial tuberosity

subtrochanteric

 

Block technique

The patient is supine, with the leg in a neutral position or rotated slightly inwards. Padding placed under the lower leg and pelvis helps facilitate puncture, but is not imperative. By passive rotation of the hip joint, it is possible to palpate and mark the greater trochanter, even in adipose patients. The puncture site is located approx. 2 cm inferior and 4 cm distal to the greater trochanter. The direction of insertion is horizontal and slightly cranial to the ischial tuberosity. Needles of between 80 and 120 mm in length are employed. The anticipated distance to the nerve can usually be judged very accurately in advance by measuring the horizontal distance from the greater trochanter to the sartorius muscle compartment. If the femur is encountered during puncture, the insertion point must be changed to the dorsal. Should stimulation at a reasonable depth fail to achieve the desired response, a correction of the insertion direction a little to the ventral will often help along with shifting the accentuation of inward rotation of the hip. Placement of a pain catheter should pose no problems.