The Hip
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Acetabular Exposure and Preparation for Reaming

(see also: acetabular component)VTHR16

Discussion

Exposure

  • for hips w/ severe osteoarthritis (or w/ heavily scarred hips) it may be necessary to fully release the quadratus femoris, and a portion of the gluteal sling;
    • because the majority of the maximus inserts into the IT band, there is little consequence of releasing the gluteal sling;
    • amount of gluteus tendon released is dependent upon how easy it is to retract proximal femur anteriorly;

protect the sciatic nervePELV4

  • note that hip flexion and knee extension will place the sciatic nerve under tension, and will risk a traction palsy with posterior retraction;
  • hence keep the hip in only slight flexion, and make sure the knee is flexed 90 deg throughout;

Capsule

  • see: anterior capsule:
  • it is important to leave the superior half of the anterior capsule intact, inorder to avoid anterior instability;
  • insert a bone hook around the greater trochanter and retract it anteriorly and laterally, which puts the anterior capsule on stretch;
  • use heavy Mayo scissors to incise the inferior half of the capsule off of its attachment to the femur;
  • alternatively, use large Kelly clamp to "puncture" and "spread" through the anterior capsule, right off of the anterior edge of the acetabulum;
  • only incise enough capsule to allow sufficient anterior translation of the proximal femur so that the acetabulum is exposed;

Retractors

anterior retractor

postero-inferior rectration

  • a "sciatic nerve retractor" or a sharp Homan retractor is placed just inferior to the posterior 1/3 of the transverse acetabular ligament;
    • hence the retractor comes to rest at the posterior ischial surface and superior to the obturator externus groove;
  • in some cases, a second retractor needs to be placed directly inferior to the transverse acetabular ligament;
  • retractors may be placed beneath the Charnley retractor and secured w/ a clamp, which then allows the assistant to handle anterior retractor;
  • if retractor is placed too anteriorly, the retractor may injure the obturator artery;
  • if retractor is placed to posteriorly, the retractor may injure the sciatic nerve;

superior rectraction

  • glutei medius and minimus are distracted anteriorly;
  • they may be restrained by inserting steinmann pin into ilium, 2 cm superior to superior margin of the acetabular labrum;

Labrum and Transverse Acetabular Ligament

  • expose bony margins of the rim of acetabulum around it entire circumference to facilitate proper placement of acetabular reaming;
    • anterior osteophytes are removed with a rongeur;
    • superior osteophytes dont require removal because they rarely cause impingement & can augment acetabular coverage of cup;
  • excise the acetabular labrum circumferentially;
  • draw soft tissues into acetabulum and divide them immediately adjacent to acetabular rim (keep knife blade within acetabulum);

transverse acetabular ligament

References