Surgical Techniques: Socket Removal

Introduction

Removing a solidly fixed, cemented or cementless acetabular component with minimal bone loss while avoiding further structural damage to the pelvis can be technically challenging as well as time consuming. The success of total hip arthroplasty (THA) depends in large part on the quality, volume, and location of host bone after implant removal. If revision surgery is not done meticulously, significant damage can occur to the host acetabulum or pelvis, further complicating reconstruction. Key factors in achieving successful acetabular implant removal are preoperative planning, selection of the correct surgical approach to provide adequate exposure, availability of correct instruments, and competence with a variety of surgical techniques.

Indications and Contraindications

A solidly fixed acetabular component may be removed during revision surgery because of chronic infection, hip instability (e.g., improper component orientation, need for a constrained prosthesis), or severe osteolysis that cannot be dealt with satisfactorily while retaining the original component. In cases of excessive polyethylene wear but a well-positioned shell, the acetabular component can remain in situ, and the polyethylene liner can be exchanged, provided the acetabular component is modular with an intact locking mechanism and the cup is solidly fixed to the pelvis. Cementation of a new liner into a well-fixed shell also is an option when the locking mechanism is damaged or the matching liner is unavailable. Revision of the acetabular component is indicated when loosening and change of the component position is identified radiographically or when stability of the component is lost with intraoperative manipulation. In all cases, the surgeon should understand why the hip is being revised and how extraction of the implant will be done.

The first step in preoperative planning is to determine the manufacturer of the component from the surgical implant labels or operative notes. Radiographs can be used when surgical notes are unavailable. Judet radiographic views or computed tomography (CT) scans can supplement standard preoperative radiographs. Anteroposterior pelvic and lateral hip radiographs can determine cup placement and the extent of bone loss and identify an associated fracture or pelvic dissociation.

During the preoperative workup, the surgeon should compare and analyze serial radiographs and identify the specific tools needed for implant removal. For example, if acetabular screws were used in the previous arthroplasty, the correct screwdriver must be selected for removal, and the surgeon must understand how the locking mechanism works for the polyethylene liner in a cementless cup.

In cases of severe component migration, such as intrapelvic component migration, angiography or CT-angiography of the pelvis is important for determining the proximity of the iliac vessels to the migrated component. A vascular or general surgeon may be needed for extraction of an intrapelvic component or in case complications arise.

Surgical Techniques