Acetabular Exposure and Preparation for Reaming : Wheeless' Textbook of Orthopaedics

Discussion

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;

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;

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;

place acetabular retractor underneath the "elevated" anterior capsule (and underneath the psoas major tendon, and on top of the pelvic brim to pull stump of neck anteriorly;
- more proximal placement of the retractor may help avoid injury to the iliac artery (due to protection of the psoas muscle);
care must be taken at this stage to avoid vascular injuries;
references:
- Common femoral artery intimal injury following total hip replacement. A case report and literature review.
- Motor-Evoked Potential Analysis of Femoral Nerve Status During Direct Anterior Approach for Total Hip Arthroplasty

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;

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;

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);