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Femoral Reconstruction Options in Revision Hip Arthroplasty
CASE STUDY
An 81-year-old woman presented with pain in the right hip and thigh that was associated with progressive difficulty in ambulating and putting weight on the right leg. She had undergone a hybrid total hip arthroplasty (THA) approximately 13 years earlier. Radiographs revealed loosening of the cemented stem with subsidence, cement mantle fracture, varus collapse, osteolysis in all Gruen zones, and Paprosky type IIIB bone loss ( Fig. 48.1 , A ). The uncemented acetabular component was well fixed. Results of the infection workup were negative, confirming aseptic loosening and failure of the femoral component.
The patient was given optimal medical care before surgery. Preoperative planning was performed to ascertain the component’s length, diameter, and offset and to determine the length of the extended trochanteric osteotomy (ETO) needed. A fluted, tapered, modular implant was chosen. Due to peculiar femoral remodeling and greater trochanteric overhang, removal of the femoral component and cement was performed with the use of an ETO. A prophylactic cable was applied distal to the osteotomy, followed by progressive manual reaming to obtain endosteal chatter (i.e., engaging hard endosteal bone to determine component size). After insertion of the distal segment of the implant, an appropriately sized trial proximal body was used to optimize leg length, offset, version, and stability, and it was confirmed with intraoperative radiographs. After the final components were implanted, the undersurface of the ETO fragment was prepared, and it was reattached with multiple cables. A socket revision was performed concomitantly to maximize hip stability. Final radiographs were obtained (see Fig. 48.1 , B to D ).
Algorithm
This is the authors’ preferred surgical algorithm for femoral reconstruction in revision total hip arthroplasty (THA) based on Paprosky’s bone-loss classification and other commonly encountered situations.
Introduction
With the increasing number of primary total hip arthroplasties (THAs) being performed, the number of revision THAs is expected to rise exponentially. In the United States alone, THA revisions may grow by 137% between 2005 and 2030. The revision surgeon may encounter various degrees of femoral bone loss at the time of revision. Depletion of femoral bone stock typically occurs as a result of multiple previous procedures involving insertion and removal of implants, infection, aseptic loosening, osteolysis due to particle debris, stress shielding, or periprosthetic fractures. Femoral revision with bone loss provides significant challenges to achieving implant fixation, stability, and durability.
Numerous options are available for femoral reconstruction in revision THA based on the extent of bone loss and the quality of remaining bone stock. They include cemented fixation, cementless fixation with the use of proximally porous-coated implants, extensively porous-coated cylindrical implants, and modular and nonmodular, fluted, tapered stems. In femurs with advanced bone loss, options include impaction bone grafting and cemented stem fixation, allograft-prosthetic composites, and proximal femoral replacement (i.e., megaprosthesis).
Indications for Revision
Classification of Femoral Bone Loss
Many classifications have been proposed for quantifying bone loss in the revision setting. They include the Mallory, Saleh, and Paprosky, schemas and the American Academy of Orthopaedic Surgeons (AAOS) classification proposed by D’Antonio and colleagues (see Chapter 46 ). The one most widely used is the Paprosky classification, which is based on the quality and quantity of metaphyseal and diaphyseal bone loss, because it provides an algorithm for planning femoral reconstruction.
Paprosky Classification
The Paprosky system divides femoral bone loss into four types and provides reconstructive recommendations. Type I consists of minimal metaphyseal cancellous bone loss and an intact diaphysis. This type of defect is commonly seen after removal of a cementless femoral component without a biologic ingrowth surface. Cemented or cementless, proximal or extensively porous-coated fixation can be used for revision.
In type II, the femur has extensive metaphyseal cancellous bone loss with an intact diaphysis. This type of bone loss is encountered after removal of a cemented femoral component. Because cemented fixation is unreliable in this situation, cementless fixation is recommended with a device for obtaining fixation in the metaphysis or diaphysis, or both.
In type IIIA, the femur has a severely damaged and unsupportive metaphysis along with more than 4 cm of intact diaphyseal bone available for distal fixation. This defect is typified by a femur after removal of a grossly loose femoral component that was inserted with a first-generation cementation technique. This level of bone loss necessitates use of a cementless, diaphyseal-fitting implant such as an extensively porous-coated, cylindrical stem.
In type IIIB, the femur has a severely damaged and unsupportive metaphysis along with less than 4 cm of diaphyseal bone available for distal fixation. This type of femur is often seen after failure of a cemented femoral component that was inserted with a cement restrictor or a cementless femoral component associated with substantial distal osteolysis. Use of a fluted, tapered, modular type of cementless stem is recommended.
In type IV, the femur has extensive metaphyseal and diaphyseal bone loss along with a widened femoral canal and nonsupportive isthmus. The reconstruction options include impaction bone grafting, an allograft-prosthetic composite, and proximal femoral replacement.
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