An 80-year-old man presented with a failed acetabular component 29 years after the index total hip arthroplasty (THA). The patient was found to be free of infection. Radiographs identified a well-fixed, uncemented stem and a combined segmental and cavitary acetabular bone deficiency. The socket had migrated 1 cm superomedially, but posterior column and superolateral coverage remained intact. He had no history of pelvic irradiation.
The patient was treated with revision of the acetabular component to a jumbo socket with a diameter of 68 mm. Multiple screws were used as adjunctive fixation for the socket. Allograft cancellous bone was placed medially to fill the remaining defect. The patient was doing well at the last follow-up, with no pain and stable implants ( Figs. 58.1 and 58.2 ).
Revision of the acetabular component with uncemented devices has a long track record of achieving reliable ingrowth. In this chapter, we discuss the indications, technique, and results of revision of the acetabular component with the use of a jumbo, uncemented, hemispherical component.
Use of a jumbo cup is a durable and versatile method of acetabular reconstruction that can manage most cases of moderate or severe bone loss.
Cases of extreme bone loss may require alternative methods of reconstruction, such as a cup–cage construct, porous-coated metal augments, and antiprotrusio devices in concert with structural or cancellous bone grafting, oblong or bilobed acetabular components, or custom triflange devices.
Appropriate exposure of the acetabulum allows safe extraction of the acetabular component and implantation of the revision component.
Great care should be taken to avoid overreaming critical areas of bone, including the posterior column, medial wall, and dome of the acetabulum.
Failure to adequately expose the acetabulum can lead to problems with component extraction and revision component implantation.
Failure to identify and treat pelvic dissociation may lead to early failure of the acetabular reconstruction.
When there is insufficient stability or contact of the socket with host bone, use of a jumbo socket alone cannot be successful.
For less severe defects, the socket can be supplemented with structural metal augments or allografts.
In cases of extreme bone loss, use of an antiprotrusio device or a custom triflange implant may be necessary. Use of a cup–cage construct promotes biologic fixation and initial stability of an ingrowth socket in the setting of deficient host bone.
Total hip arthroplasty (THA) is the best treatment option for a variety of end-stage hip conditions. Some of these patients eventually require revision of the acetabular component. One study reported that the most common causes of revision THAs were instability or dislocation (22.5%), mechanical loosening (19.7%), and infection (14.8%). All-component revision was performed in 41% of cases, and isolated acetabular component revision was performed in 12.7% of cases. Management of failed acetabular components in an efficient and durable way will become increasingly important as the number of hip revisions grows over the next 20 years.
Indications and Contraindications
The goal of acetabular revision is to restore a durable, well-functioning implant (e.g., pain relief, stability) while minimizing bone and soft tissue damage. The use of an uncemented, hemispherical acetabular component is indicated for most acetabular component revisions. Use of a jumbo socket is indicated when the extra-large, hemispherical component allows the surgeon to overream through smaller cavitary or segmental bone defects to enable adequate initial fixation on host bone. Patients with Paprosky type I, IIA, and IIC defects typically are best managed with this form of reconstruction. Some patients with type IIIA defects and spherical osseous remodeling may also be candidates for jumbo cup reconstruction.
All patients must be evaluated for infection before surgery because active infection is an absolute contraindication. Eradication of the infection should be confirmed before definitive acetabular reconstruction.
An extra-large, hemispherical component cannot be used in isolation if there is inadequate host bone available for contact and support. This is confirmed when the trial or revision component is unstable in response to a force directed posteriorly or superiorly. The surgeon must use alternative methods, such as structural allografting, porous-coated metal augments, cup–cage constructs, antiprotrusio devices, or custom triflange devices. Pelvic dissociation must also be identified and treated.
Successful use of a jumbo socket requires viable host bone in contact with the revision component. Patients with a history of bulk allograft or high-dose pelvic irradiation may have nonviable bone and should be considered for an alternative method of reconstruction.
Use of a jumbo socket requires certain equipment:
Implant extraction tools, including curved acetabular gouges for acetabular component removal
Cement extraction tools as needed
Implant-specific extraction devices (e.g., screwdrivers, liner extraction tools)
Femoral modular components or other revision components as indicated
Revision acetabular components that allow multiple-screw fixation
Large-diameter bearing surfaces that maximize stability
Examination and Imaging
Preoperative planning is essential. Operative notes and implant records for previous procedures should be obtained to ensure that appropriate extraction tools and revision components are available.
All patients should be evaluated with a thorough history and physical examination, focusing on historical features that suggest wound healing problems, infection, or instability. The nature, location, and timing of pain should be assessed. All patients with a painful THA or in need of revision surgery should be evaluated for occult infection with the use of serologic inflammatory markers, including the erythrocyte sedimentation rate and C-reactive protein. If these values are elevated and infection is suspected (e.g., history of prolonged wound drainage, previous postoperative débridement), the patient’s hip should be aspirated for a white blood cell count with a differential and culture.
A complete radiographic assessment should be obtained. At our institution, the typical evaluation includes anteroposterior radiographs of the pelvis and proximal femur, a true lateral radiograph of the hip, and a lateral, frog-view radiograph. In cases of more significant bone loss, Judet or false-profile oblique views can help in visualizing the integrity of the anterior and posterior columns. Cemented sockets typically are evaluated for loosening using the system described by Hodgkinson and co-workers ( Table 58.1 ). Uncemented sockets are typically evaluated according to the system described by Massin and colleagues ( Box 58.1 ).