1 Principles topenlarge
Definition: Anterior column fractures
Anterior column fractures separate a segment of anterior acetabulum from the rest of the innominate bone. The fracture starts from the middle of the ischiopubic ramus below, then passes through the anterior acetabulum. The proximal extension of this fracture passes variably through the innominate bone, at different levels above the acetabulum, as far upwards as the middle third of the iliac crest.
Anterior column fractures are classified by the level of their proximal end. Depending on this level, we distinguish very low, low, intermediate, and high fracture types.
Low and very low fractures
In low fractures, the upper margin of the fracture extends to the level of the psoas gutter. The anterior wall of the acetabulum and a small amount of its roof are separated from the remaining anterior column (see figure).
In very low fractures, the displaced fragment comprises the lowest part of the anterior wall, adjacent anterior column, and the related acetabular surface. The superior fracture line transsects the anterior wall and descends through the fovial notch (not illustrated).
The upper margin of the fracture extends to the level between the anterior superior and inferior iliac spines. This fracture separates a larger portion of the anterior column and wall from the intact acetabulum.
Often, a comminuted portion of the quadrilateral surface is detached and hinged posteriorly.
The upper margin of the fracture extends to the level of the iliac crest, as far backwards as its middle third.
This fracture separates a massive segment of the anterior column, containing the anterior wall with its related articular surface. It involves nearly all of the roof, and the front part of the iliac wing.
Anterior column fractures are often comminuted, splitting the free part into several pieces.
Dislocation of the femoral head
Displacement of the anterior column fragment always is the result of an anterior femoral head displacement or dislocation. The head of the femur pushes the fragments anteriorly and typically remains displaced anteriorly and medially, dislocated from the posterior articular surface.
The head is easily visible in the fracture gap. The pelvic brim fragment is rotated externally around its long axis. The quadrilateral plate is rotated internally.
The CT view reminds us of the swinging doors of traditional style Western saloons.
Intraarticular fracture fragments and marginal impaction
Part of the internal portion of the roof may appear isolated or be impacted into the underlying cancellous bone. Intraarticular fracture fragments and marginal impaction create a condition of incongruity and instability.
Femoral head damage
Due to dislocation, the femoral head may show areas of contusion, abrasion, or indentation.
These conditions can not be reversed and worsen the prognosis.
2 Principles of reduction topenlarge
Closed reduction of anterior hip dislocation
Femoral head dislocation should be reduced urgently. Anterior dislocations often accompany anterior column fractures. Reduction is usually obtained by manual traction, and leg manipulation. If closed reduction is unstable, it may be helpful to use the large distractor (see below).
Reduction is facilitated by hip flexion, in order to relax the hip flexor muscles, which cross anterior to the hip joint.
Reduction may also be maintained by applying skeletal traction to the femur with the fracture table.
Open fracture reduction, from peripheral to central
Anterior column fractures are reduced from peripheral to central, starting with the proximal end of the fracture, at the level of the iliac crest (or below), and ending at the acetabular fossa. The peripheral reduction must be anatomical, since displacement there will aggravate malreduction at the acetabular fossa.
Reduction of anterior column fractures, through the ilioinguinal approach, is indirect. The articular surface of the hip joint is not seen directly. Reduction must be assessed by the appearance of the extraarticular fracture lines, and intraoperative fluoroscopic assessment.
Interpretation of radiographic anatomy involves the six fundamental landmarks of Letournel:
(1) Posterior wall of the acetabulum
(2) Anterior wall of the acetabulum
(3) Roof (dome or tectum)
(5) Ilioischial line (posterior column)
(6) Iliopectineal line (anterior column)
Impacted articular fragments must be elevated
Reduction of all fracture fragments is critical to the final outcome. Marginal impacted fragments are common. They must be elevated and supported with bone grafts.
Skeletal traction aids anterior column reduction
Traction may be applied through a Schanz screw in the greater trochanter, manually or attached to fracture table.
Insert a Schanz screw along the axis of the femoral neck, through a short, separate incision over the greater trochanter.
The large distractor is applied with the following technique.
Insert the proximal 5 mm Schanz screw in the sciatic buttress placed from anteriorly to posteriorly.
Place the distal Schanz screw into the femur at the level of the lesser trochanter from anteriorly to posteriorly. Attach the distractor as shown to these two screws.
Center the head under the roof using a combination of longitudinal traction, limb position, and manual lateral traction.
Verify the femoral head reduction with the image intensifier.
Hold the reduction by tightening the large distractor.
3 Marginal impaction topenlarge
Elevate impacted fragments
In case of a subchondral impaction of the articular surface, carefully elevate and mold the area to fit the reduced femoral head.
Fill the defect
Fill the defect zone with cancellous autograft or a bone substitute.
4 Fracture reduction top
Cleaning of the fracture site
Clean and irrigate the fracture site in preparation for the reduction.
Reduction with clamps
Reduction is achieved with the help of a Farabeuf clamp, pointed reduction forceps, and/or one or more of the specialty pelvic clamps. A ball spike pusher is very helpful for final fragment reduction.
The anterior column fracture fragment is manipulated with a Farabeuf clamp or possibly a Schanz screw (higher fractures).
Reduction starts at the upper fracture margin. First reduce the peripheral end of the fracture (iliac crest).
Provisional fixation is provided by a pointed reduction forceps across the reduced fracture at the iliac crest.
Another clamp is placed between the reduced pelvic brim fragment and the external surface of the bone just lateral to the anterior inferior iliac spine.
Depending upon fracture configuration, additional clamps may be useful.
Provisional fixation can be stabilized with temporary K-wires.
5 Definitive fixation topenlarge
Lag screw osteosynthesis
For fixation of the upper part of the anterior column fracture, lag screw osteosynthesis is preferable. At the iliac crest use small fragment screws (long 3.5 mm). At the level of the pelvic brim, larger screws may be used (see considerations for safe screw placement).
Additional lag screws
At the pelvic brim segment, one or two additional isolated interfragmentary lag screws can be applied from the anterior into the posterior column (see considerations for safe screw placement).
Make sure to insert every screw extraarticularly.
As a rule, isolated lag screw placement does not provide adequate fracture stability.
Position lag screws so they do not interfere with optimal plate location.
Plate fixation of iliac crest
A plate across the fracture line at the iliac crest can be used to supplement or replace lag screw fixation at this level.
Pelvic brim neutralization plate
Neutralize the reduced fracture with a precontoured small-fragment pelvic reconstruction plate applied to fit the reduced fracture.
The plate bridges the reduced pelvic brim segment of the anterior column. It extends superiorly to the inner part of the iliac fossa in front of the sacroiliac joint and inferiorly to the intact part of the superior pubic ramus and the body of the pubis.
A sufficient number of screws is placed through the plate holes. Interfragmentary lag screws can also be applied through the plate. Every screw should be placed extraarticularly.
In case of osteoporotic bone adequate anchorage of the neutralization plate is only obtained by the use of very long screws in the first and last holes of the plate near the sacroiliac joint and the symphysis pubis. Typically, more screws are required in osteoporotic bone.
Confirm reduction and screw placement
Confirm fracture reduction with AP, iliac and obturator oblique radiographs. The position of all screws should be assessed, particularly those close to the acetabulum. An image centered over a screw and aimed along its axis is the best way to ensure that it does not enter the hip joint.
6 Wound closure topenlarge
Before closure, one may place drains in the space of Retzius and anterior internal iliac fossa.
Layered closure then begins with repair of the conjoint tendon to the distal inguinal ligament. A careful fascial repair restores the floor of the inguinal canal.
The external oblique aponeurosis and the rectus sheath are then repaired, followed by secure reattachment of the abdominal wall origin to the iliac crest, in the lateral portion of the incision. A hernia-free repair, and avoidance of entrapment of the spermatic cord should be achieved.
Subcutaneous drains may be inserted.
Finally, perform an appropriate subcutaneous and skin closure.