Executive Editor: Peter Trafton

Authors: Keith Mayo, Michel Oransky, Pol Rommens, Carlos Sancineto

Acetabulum

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Glossary

Trochanter flip extension
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Introduction

The trochanter flip (digastric trochanteric osteotomy) can be used to extend the exposure of the Kocher-Langenbeck approach superiorly and anteriorly.
When full exposure of the inferior portion of the posterior column is not required, this trochanteric flip osteotomy can be utilized as well with the Gibson approach.
This exposure can be combined with a surgical dislocation of the hip in more complex injury patterns.
 

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  • in dark brown: Direct access
  • in light brown: Digital or clamp access

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The most common use for this approach variant is the postero-superior wall fracture.
In addition, certain transverse, transverse plus posterior wall, T-shaped, and associated posterior column plus posterior wall fracture patterns may be treated using this approach.
Factors which would favor this alternative include superior wall extension or a transtectal transverse fracture component in a patient thought to be a poor candidate for an extensile or combined approach.


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Skin incision

With the hip in a neutral rotation position, a long straight lateral incision is made. The straight proximal limb illustrated is the Gibson variation.
The usual skin incision begins 10-15 cm proximal to the trochanter and extends an additional 10-15 cm along the proximal lateral femur.
The total length of the incision is dictated by the body habitus of the patient.


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Superficial surgical dissection

Deepen the incision through subcutaneous fat.
The interval between the gluteus maximus and medius must be delineated. This is accomplished more easily in the proximal portion of the wound. This fascial incision is continued distally to split the iliotibial tract longitudinally.
In some cases it may be necessary to release a portion of the gluteus maximus tendineous insertion onto the femur in the distal portion of the wound. This facilitates posterior retraction in the larger patient.
The gluteus medius fascia is mobilized with the gluteus maximus muscle belly allowing preservation of important vascular supply from the superior gluteal artery.


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Deep dissection

Two vascular landmarks assist in the identification of external rotator anatomy. The trochanteric anastomosis communicates with the ascending branch of the medial femoral circumflex at the cranial border of the quadratus femoris.
The second landmark is provided by the superior gluteal artery branch which traverses the inferior border of the piriformis tendon. This vessel also anastomoses with the ascending medial femoral circumflex.

Evaluate the sciatic nerve
Next the sciatic nerve is localized in its path posterior to the quadratus femoris.
It is traced proximally to the level of the piriformis, and any anomalies in neural anatomy are noted.
In the majority of the cases the sciatic nerve is a single trunk which passes anterior to the piriformis as it enters the greater sciatic notch. In these cases the piriformis is left attached to the trochanter, and no further dissection is carried out in the zone of the short external rotators.


Note
In cases where the sciatic nerve is bifid or penetrates the substance of the piriformis, it may be prudent to release the piriformis 1 cm posterior to the trochanter. This will limit the potential traction on the nerve if surgical dislocation of the femoral head is required.


Develop the piriformis muscle
This requires inferior retraction of the piriformis and superior retraction of the medius. The minimus is sharply mobilized beginning along its inferior fascial border. The release extends posteriorly to the greater sciatic notch, taking care to avoid injury to the superior gluteal neurovascular bundle. The initial anterior dissection proceeds to the mid supra-acetabular area.


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Develop the minimus-piriformis interval

Next the interval between the piriformis and gluteus minimus is developed.
This requires inferior retraction of the piriformis.
The minimus muscle should be protected because it carries the circumflex vessels. It is sharply released from the retroacetabular surface.


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Trochanteric osteotomy

The plane of the trochanteric osteotomy is then prepared by cauterizing the trochanteric anastomotic vessels.
It may be useful to predrill the trochanter for subsequent reattachment prior to the osteotomy.
The osteotomy is then carried out from the tip of the trochanter to the base of the vastus tubercle using a saline-cooled oscillating saw. A small portion of the medius tendon is left temporarily attached to the intact femur until the trochanter can be mobilized. This provides an additional aid to prevent injury to the retinacular vessels caused by an excessively thick osteotomy.


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Anterior exposure and mobilization gluteus minimus

The vastus lateralis fascia is incised from the vastus tubercle distally a distance of 5-8 cm to allow extra periosteal mobilization of the proximal lateralis muscle belly with the trochanteric segment.
The trochanter is progressively everted utilizing a Hohmann retractor placed over the anterior aspect of the greater trochanter. Now, the small remaining gluteus medius attachment to the intact trochanteric ridge is released. At times the piriformis insertion will be partially attached to the mobile trochanteric fragment. This should be released as the trochanter is everted.
Flex and externally rotate the hip to improve anterior exposure.
This allows complete mobilization of the gluteus minimus from the retroacetabular surface along the superior capsule to its femoral insertion along the anterior aspect of the trochanter.
The minimus insertion may also straddle the trochanteric osteotomy. If so, it must be released from the intact femur to allow full trochanteric mobilization.


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Hemicircumferential view of the acetabular rim

Exposure of the anterior capsule requires mobilization of the proximal portion of the vastus intermedius.
Once this is achieved, a hemicircumferential view of the acetabular rim and capsule is provided. This starts posterior and inferior to the retracted piriformis tendon and extends anteriorly around the acetabulum to the level of the reflected head of the rectus.


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Capsulotomy

Intraarticular visualization is provided by a Z-shaped capsulotomy.
This aids reduction of fractures which do not have a posterior or superior wall component. Retraction sutures are useful.


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Reflect the posterior wall fragment

When a posterior wall fracture is present, the capsular pedicle to the wall fragments must be preserved. The capsulotomy is modified to incorporate the posterior wall at its margin.
The wall fragments are then reflected inferiorly to assist in joint visualization. The labrum is typically intact at the anterior aspect of the wall fragment, but is avulsed at the postero-inferior margin.


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Release conjoint tendon for additional exposure

For many fractures the surgical exposure is now complete. It is possible with this exposure to tunnel anterior to the short external rotator tendons for plate application along the posterior column.
If this becomes too difficult, the piriformis and conjoint tendon of the obturator internus and gemelli muscles can be released at least 2 cm posterior to their insertions for additional exposure.
The repair of these tendons at the time of closure represents additional risk to the femoral head circulation.
Passage of a needle into the tendon stump may injure the ascending branch of the medial femoral circumflex artery. 


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Dislocation of the hip joint

“Figure of four” extension of the approach
More complex fracture patterns may require extension of this approach to include anterior surgical dislocation.
This is accomplished by careful placement of the involved limb in a “figure-four” position (flexion to 90 degrees combined with adduction and external rotation).
A sterile pouch is required for this maneuver. Divide the ligamentum teres with a pair of curved scissors to reduce the force required for dislocation.


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Dislocation of the femoral head
With the femoral head dislocated, appropriate anterior and posterior retraction provides a panoramic view of the joint.


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Visualization of anterior column and limb

Dislocation is best used for visualization and reduction of the anterior column or anterior limb of the ischiopubic segment.
However, because of soft-tissue limitations it is usually necessary to relocate the hip to provide access for implant insertion.
The sequence of dislocation and reduction may have to be repeated multiple times during the reconstruction.


Closure

For many fractures the surgical exposure is now complete. It is possible with this exposure to tunnel anterior to the short external rotator tendons for plate application along the posterior column.
If this becomes too difficult, the piriformis and conjoint tendon of the obturator internus and gemelli muscles can be released at least 2 cm posterior to their insertions for additional exposure.
The repair of these tendons at the time of closure represents additional risk to the femoral head circulation.
Passage of a needle into the tendon stump may injure the ascending branch of the medial femoral circumflex artery. 

When the reconstruction is completed, the capsule is closed loosely to allow drainage of any secondary hemarthrosis.
The trochanter is then reattached with lag screws. The number (2-3) and diameter (3.5-4.0) of screws utilized is dependent on bone density.

The vastus lateralis fascia is repaired and the short rotator tendons are reapproximated.
Deep drains are placed as needed. The gluteus maximus tendon is repaired, and lastly, the iliotibial tract and gluteal fascia are closed.
Subcutaneous drains follow, and subcutaneous and skin closure are completed.

v1.0 2007-07-22