Ganz Surgical Dislocation of Hip
Surgical dislocation of the adult hip: A technique with full access to the femoral head & acetabulum without the risk of avascular necrosis
R Ganz, T J Gill, E Gautier, K Ganz, et al. Journal of Bone & Joint Surgery. (British volume). London: Nov 2001. Vol.83, Iss. 8; pg. 1119, 6 pgs
Principles
- blood supply to the femoral head is mainly from the deep branch of the medial femoral circumflex artery (MFCA)
- During dislocation of the hip, this vessel is protected by the intact obturator externus muscle
- Using a trochanteric flip approach the hip can be exposed anteriorly, subluxated & dislocated in the same direction, if required, while respecting the integrity of the external rotator muscles
- This allows a gap of up to 11 cm between the head & the acetabulum, giving a view of the femoral head of about 360° & a full 360° view of the acetabulum
Position
- lateral decubitus position
Incision
- Posterior Kocher-Langenbeck incision is made & the fascia lata split accordingly
Superficial Dissection
- leg is then internally rotated & the posterior border of gluteus medius identified
- No attempt is made to mobilise gluteus medius or to visualise the tendon of piriformis
- An incision is made from the posterosuperior edge of the greater trochanter extending distally to the posterior border of the ridge of vastus lateralis
Deep Dissection
- A trochanteric osteotomy with a maximal thickness of about 1.5 cm is made along this line with an oscillating saw
- At its proximal limit, the osteotomy should exit just anterior to the most posterior insertion of gluteus medius
- This preserves & protects the profundus branch of the MFCA, which becomes intracapsular at the level of the superior gemellus muscle
- greater trochanteric fragment is mobilised anteriorly with its attached vastus lateralis after releasing it along its posterior border to about the middle of the tendon of gluteus maximus
- most posterior fibres of gluteus medius are also released from the remaining trochanteric base
- osteotomy is correct when only part of the fibres of the tendon of piriformis has to be released from the trochanteric fragment for its further mobilisation
- With the leg flexed & slightly rotated externally vastus lateralis & intermedius are elevated from the lateral & anterior aspects of the proximal femur
- tendon of piriformis becomes visible by careful anterosuperior retraction of the posterior border of gluteus medius
- inferior border of gluteus minimus is separated from the relaxed piriformis & underlying capsule
- constant anastomosis between the inferior gluteal artery & MFCA, which runs along the distal border of the piriformis muscle & tendon, is preserved
- Care has to be taken to avoid injury to the sciatic nerve, which passes inferior to the piriformis muscle into the pelvis. When the nerve is double branched, the piriformis muscle is sandwiched between the branches & its insertion into the greater trochanter should be released to avoid stretching the branches of the nerve during dislocation
- entire flap, including gluteus minimus, is retracted anteriorly & superiorly to expose the superior capsule. This is facilitated by further flexion & external rotation of the hip. The anterior, superior & posterosuperior capsule can now be visualised
- capsule is first incised anterolaterally along the long axis of the femoral neck since incision in this area avoids injury to the deep branch of the MFCA. An anteroinferior capsular incision is made. The capsulotomy must remain anterior to the lesser trochanter in order to avoid damage to the main branch of the MFCA, which lies just superior & posterior to the lesser trochanter
- Elevation of the anteroinferior flap allows visualisation of the labrum
- first capsular incision is then extended towards the acetabular rim where it is sharply turned posteriorly parallel to the labrum reaching the retracted tendon of piriformis. Care must be taken not to damage the labrum
- hip can now be dislocated; the leg is flexed, externally rotated, brought over the front of the operating table, & placed in a sterile bag allowing inspection of most of the acetabulum
- greater trochanter is reattached using two or three 3.5 mm cortical screws or cerclage wire
