1 General considerations top
General remarks for sequential approach
Any anterior approach ( modified Stoppa or ilioinguinal approach) can be combined with any posterior approach. Here a combination of the Stoppa approach and the prone Kocher-Langenbeck approach is illustrated as the easiest and most reliable combination.
Sequence of the treatment
For ORIF of anterior column/posterior hemitransverse fractures (ACPHT) with a sequential approach, the following surgical sequence is common:
- Patient positioning supine for Stoppa approach
- Direct reduction of the anterior column
- Assessment of reduction
- Fixation of the anterior column avoiding posterior column
- Wound closure
- Patient positioning prone for Kocher-Langenbeck approach
- Direct reduction of the posterior column
- Assessment of reduction
- Fixation of the posterior column
Preoperative templating is essential for understanding the complexity of an acetabular fracture.
When using implants on the innominate bone, it is important to know the best starting points for obtaining optimal screw anchorage (see General stabilization principles and screw directions).
Approach windows for the anterior column
Many fractures can be treated with use of the Stoppa window only. The lateral window may supplement this.
Fractures with low and intermediate anterior column elements will only require a Stoppa window (B).
Only high anterior column fractures (A) may benefit from a lateral window to allow control of the iliac crest and supplemental fixation.
2 Principles of reduction top
Open fracture reduction
The Stoppa approach allows direct control of the anterior column around the acetabulum and it is often possible to control the reduction entirely at the level of the pelvic brim. This may enable the lateral window to become unnecessary and the approach limited to the Stoppa window only.
Unusually for a significant joint, articular reduction of acetabular fractures 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. Some fracture lines are palpated manually but not seen directly such as transverse fracture lines on the quadrilateral plate.
Quality of reduction
Posttraumatic arthrosis is directly related to the quality of reduction - the better the reduction, the greater the chance of a good or excellent result.
3 Joint distraction topenlarge
Application of traction
It is important to ensure hip flexion to allow enhanced exposure of the iliac fossa and true pelvis.
The anterior column/posterior hemitransverse fracture is a result of medial displacement of the femoral head at the time of injury. In order to allow manipulation of the anterior column element, the femoral head must be distracted. This is typically accomplished with the application of lateral and/or distal traction.
It may be successful to push the femoral head out of the pelvis using a ball spike pusher.
Otherwise this may be accomplished with the application of lateral or distal traction.
In some surgeon’s experience, the use of a traction table post or other traction frame is helpful during this operation.
Center the femoral head under the radiological roof using a combination of lateral traction, distal/longitudinal traction, and limb positioning.
Verify the femoral head reduction with the image intensifier.
Lateral traction with a trochanter screw
Traction may be applied through a Schanz screw in the greater trochanter, manually or attached to a fracture table.
Insert the screw along the axis of the femoral neck, through a short, separate incision over the greater trochanter.
Distal or longitudinal traction may be applied in the axis of the femur. This can be accomplished manually via a distal femoral traction pin or via a fracture table.
Alternatively, a large distractor may be applied using the following technique.
Insert the proximal 5 mm Schanz screw in the sciatic buttress placed from anterior to posterior. This screw must be cranial to the fracture and into an intact segment of the innominate bone. Based on the fracture through the ilium, this screw may not be possible in high anterior column fractures.
Place the distal Schanz screw into the femur at the level of the lesser trochanter from anterior to posterior. Attach the distractor as shown to these two screws.
AO teaching video: Use of the distractor on the pelvis
4 Cleaning of the fracture site top
Fracture sites are prepared by preliminarily increasing the displacement and then removing early callus and granulation tissue.
Joint distraction is extremely useful to facilitate this debridement.
5 Anterior column: reduction and fixation top
Fixation with a pelvic brim plate
A contoured pelvic brim plate is used through the Stoppa approach. This plate can be contoured as required by the specific fracture.
The plate must be long enough to provide adequate fixation above and below the acetabulum. This typically requires extension to the pubic body.
It is likely that the application of the plate will facilitate some or all of the reduction.
Contouring the plate
Contour the plate to fit the anterior column in advance of the reduction.
The use of a malleable template aids plate contouring.
Because the primary purpose of this plate is to buttress the anterior column, posterior contouring is most critical. For this reason, plate fixation normally starts posteriorly and proceeds anteriorly. Final adjustment of the plate profile can be achieved in situ, due to plate malleability.
Tools for in situ plate contouring include the ball spike for pushing, ...
... and large and small fragment screwdrivers for torsional adjustment.
Plate fixation of the anterior column
The plate is positioned in the medial iliac fossa adjacent to the SI joint. The cranial screw is placed proximal to the fracture in an anterior to posterior direction parallel to the SI joint, and typically measures 40 mm in length. The screw drives the plate down and buttresses the elevated anterior column fragment, completing the reduction.
The next two screws may have the proximal cortex overdrilled with a 4.5 mm drill if further compression of the fracture is required.
Care should be taken to avoid inadvertent violation of the SI joint.
The proximal fixation is typically shorter than with an ilioinguinal approach and the fixation includes screws through the proximal part of the fracture.
The interfragmentary screws applied through the plate ensure compression of the fracture and provide additional stability above the acetabulum. Care should be taken to ensure that each screw is placed extraarticularly, as this region is juxtaarticular.
Completion of the fixation to the plate near the pubic fracture provides completed anterior column fixation.
Fixation of high anterior column fractures
High fractures will be adequately controlled by the fixation at the pelvic brim. It may be necessary to supplement this with the addition of a lateral window.
With an approach through a small lateral window, direct reduction and screw or plate fixation can be completed.
6 Posterior column: reduction topenlarge
Repositioning of the patient and Kocher-Langenbeck approach
At this stage of the surgery the anterior exposure is closed, the patient is repositioned prone and the posterior column exposed through the Kocher-Langenbeck approach.
Ischial Schanz screw as a handle
A Schanz screw is placed into the ischial tuberosity to act as a handle or joystick. This is a key aid for manipulating the posterior column fragment.
The orientation of the screw is directed from lateral to medial and is typically applied through the muscular insertions overlaying the tuberosity. The muscles do not need to be elevated from the bone to allow screw placement.
Care should be taken to avoid blocking the fracture environment with this screw. A proximal to distal trajectory should be avoided, as the Schanz screw will block subsequent adjuncts for fracture reduction at the retroacetabular surface.
Use of pointed push pull devices
Fracture adjustment requires fine manipulation at the fracture itself. There are several adjuncts that can accomplish this fine adjustment.
Rotation and fine adjustment of this fragment is aided with a bone hook, sharp dental hooks, and/or ball spike pusher.
Manipulation with a hook placed as shown demonstrates mobility of the posterior column, and helps in the reduction. If reduction is difficult, check the fracture site for interposed debris.
Use of pointed reduction forceps
The pointed reduction forceps is a very powerful way of manipulating the reduction along the fracture line and applying compression.
Due to the convexity of the bone, small holes may need to be drilled into the cortex to allow clamp application, and to prevent the points from slipping.
Use of a Farabeuf clamp
This clamp has jaws shaped to fit around screw heads. It can be used to compress fracture surfaces with two properly placed 3.5 mm cortical screws. They should be securely placed, and a little prominent, to be grasped by the clamp.
Properly placed, this clamp can both de-rotate the posterior column, and approximate the fracture fragments.
Care should be taken, as poor clamp placement may pressure the sciatic nerve.
Use of a Jungbluth clamp
The Jungbluth pelvic reduction clamp is a similar alternative, which requires a larger exposure and also depends upon proper screw placement so that the forces applied by the clamp correctly realign the fracture.
A proximal screw is placed in the superior portion of the iliac wing above the acetabulum.
A distal screw is placed in the posterior column above the ischial tuberosity.
Their positions determine the direction of applied force, and this must be perpendicular to the fracture plane.
The use of the screw-dependent clamps (the Jungbluth and Farabeuf) creates the potential problem of screw traffic. Care must be taken to avoid placing these screws in the way of provisional and definitive fixation screws.
Articular surface reduction
In the elementary posterior column fracture, the articular surface cannot be easily visualized once the fracture has been reduced. This is different than the associated posterior column/wall fracture, in which the posterior column articular reduction can be assessed through the displaced posterior wall fragment.
Intraarticular inspection may be possible by opening the hip capsule with an incision parallel to the acetabular border, avoiding damage to the labrum. Inspection of the joint surface demonstrates reduction.
The reduction of the cortical surfaces of the fracture acts as a surrogate for articular reduction. Visualization of the fraction line along the cortical retroacetabular surface and palpation of the fracture along the quadrilateral surface together indicate the quality of the obtained reduction.
Examine the reduction by inserting a finger or an appropriate instrument along the quadrilateral plate. With a satisfactory reduction, the quadrilateral surface should have no palpable gap or step-off.
Additional manipulation of translation and rotation of the posterior column fragment should occur until both the internal palpation and external visualization demonstrate an anatomical reduction.
To mobilize the posterior column in cases older than 3 weeks, cut the sacrospinous ligament at its insertion on the ischial spine to aid mobilization of the fragment.
7 Posterior column: fixation topenlarge
Interfragmentary lag screw
If possible, begin definitive fixation with an interfragmentary lag screw, placed from the distal fragment, into the posterior buttress of the ilium. The trajectory of this screw often requires a percutaneous insertion through the posterior gluteus musculature. Great care must be taken not to compromise the sciatic nerve.
The gliding hole may be drilled before reduction to ensure its proper placement.
Screw placement must allow optimal plate positioning as described below.
Contouring of the plate with a template
In addition to the lag screw, a reconstruction plate will be applied. The two points of fixation will provide torsional stability to the ultimate construct.
A reconstruction plate is chosen to reconstitute the structural stability of the native posterior column and the sciatic buttress. Ideally, it will be applied to the mid-column and contoured to obtain purchase in the strong bone of the sciatic buttress.
An aluminum template can be bent to fit the pelvis in the optimal location. The plate positioning will be limited cranially by the superior gluteal nerve and vascular pedicle. The distal end of the plate will be contoured to optimize screw positioning down the ischial ramus.
The plate contour should enforce the vectors required for the reduction.
Application of the reconstruction plate
Definitive stabilization is obtained by adding the reconstruction plate spanning the posterior column and anchored securely to the ilium and ischium.
The screws placed in the periarticular portion of the plate must be positioned carefully to avoid intraarticular perforation. This becomes more probable as the plate is positioned laterally and closer to the acetabular rim.
Pitfall: Injury to gluteal vessels and nerve
Proximally, retraction and plate and screw placement may result in neurovascular injury. Careful retraction and attention to plate location are essential to protect these fragile structures.
8 Radiographic assessment top
Intraoperative confirmation of hardware position
During reduction and fixation, take fluoroscopic images in AP, iliac, and obturator oblique views to confirm reduction and/or screw placement.
To confirm that the lag screws are extraarticular an image exposed with the fluoroscope’s central ray superimposed on the long axis of the screw is taken.
Final radiographic assessment
Once all fixation is in place, confirm the appropriate appearance of AP, obturator oblique and iliac oblique views and check the location of any screw that is placed near the hip joint.
Postoperatively, obtain formal high-quality radiographs of AP and both oblique views.