Protrusion through the medial wall of the acetabulum can occur from any approach. Careful attention should be paid to the visualization of any soft tissue at the base of the acetabulum while reaming.
Note: If the medial wall is compromised, the musculature of the obturator internus and potentially the obturator neurovascular bundle can be encountered.
A simple protrusion does not typically lead to an unstable acetabular cup unless there is an underlying deformity of the pelvis. Instability might be present if the protrusion is more complex and involves the columns of the acetabulum (pelvic discontinuity). They are best addressed through an additional anterior intrapelvic approach, with the patient in supine position.
3. Cup removal
In the setting of infection, loosening, or osteolysis, cup removal may lead to acute bone loss and/or the creation of periprosthetic fractures. If this destabilizes the acetabular support of the arthroplasty, fracture specific reduction and fixation techniques are necessary. Depending on the fracture pattern, ORIF with plate and screw and/or column fixation may be indicated.
It is critical to remove the cup without causing additional fractures or bone defects.
Protrusio and/or central dislocation type fractures should be reduced if the cup does not have adequate support. This requires buttress fixation.
Protrusio preventing intraoperative cup stability
Protrusio or central dislocation type fractures that prevent cup stability intraoperatively are open reduced. Stability is typically achieved with a brim plate applied to buttress the anterior wall or column and if necessary, a quadrilateral buttress plate can be applied.
Reduction and stabilization of the fracture should be confirmed using fluoroscopy.
5. New acetabular cup/cage implantation
A multi-hole cup is used when there is enough acetabular support.
Postoperative management should include careful monitoring of hematocrit and electrolytes particularly in the elderly patients.
Postoperative IV antibiotics should be administered up to 24 hours.
Consideration should be given to anticoagulation for a minimal course of 35 days. If there are thromboembolic complication this treatment is extended.
Drains can be discontinued when output is less than 30 to 50 cc per 12 hours.
Immediate mobilization of the patient should commence. If fracture stability will allow, the patient should be made weight bearing as tolerated as soon as possible. Long periods of limited weight bearing are extremely detrimental to patient recovery.
Precautions against hip dislocation
Hip precautions can be extremely important in patients who have suffered intraoperative acetabular fracture. Much work has been done to minimize the surgical exposure during hip arthroplasty to decrease the risk of dislocation. These advantages are typically removed when acetabular stabilization need to be performed. A dislocation in the postoperative course of such a patient can be disastrous.
Patients are instructed to follow standard hip precautions against dislocation based upon the surgical approaches for hip arthroplasty.
Avoidance of edema postoperatively is critical for both wound healing and patient mobilization. This can be aided by pneumatic compression devices. If negative pressure wound therapy is utilized, it can be discontinued after 5 to 7 days. Staples or sutures are typically removed at 14 to 21 days.