Extraction of well-fixed extended porous-coated cementless stems using a femoral longitudinal split procedure

We herein described a useful method, referred to as the femoral longitudinal split (FLS) procedure, for the extraction of well-fixed extended porous-coated cementless stems while preserving the normal configuration of the proximal femur. Using the FLS procedure, we achieved the successful extraction of the femoral stem in 8 out of 10 patients who had extended porous-coated cementless femoral stems.

The extracted stem was an extended porous-coated stem in each case. Although one hip had fibrous stable fixation, 11 hips were evaluated radiographically with bone ingrown fixation. When removing osseointegrated cementless stems, debonding of the stem from the surrounding bone using a thin osteotome can be difficult. ETO offers a method for extraction in which the lateral femoral fragment is opened longitudinally to visualize the whole stem, followed by the use of a thin or wire osteotome to debond and remove the stem [1, 2]. In contrast, our method, based on the FLS procedure, affords a minimally invasive stem extraction procedure in which the posterior aspect of the proximal femur is split.

Jack et al. [3] reported satisfactory clinical results for 18 patients who underwent revision THA with slot femoral osteotomy while leaving the most proximal metaphysis intact. In this study, however, 80 % of the extracted stems were curved anatomic stems fixed in the metaphysis. Bauze [4] also reported posterior longitudinal split osteotomy for femoral component extraction in revision total hip arthroplasty. However, these authors did not include extended porous-coated stems [5]. In contrast, the fact that almost of the stems in our series were distally osseointegrated extended porous-coated stems suggests that a more extensive split osteotomy through the proximal part of the femur to facilitate extraction of the stem was required. In our method, a Kirschner wire was used to drill multiple small holes (2.0 mm in diameter) at 1-cm intervals longitudinally along the exposed posterior linea aspera to the femoral stem, and these small holes were connected by an osteotome to make a femoral longitudinal split (Fig. 1). This process did not leave any longitudinal bone defects in the femur. The use of tight cerclage wiring, consisting of ultrahigh molecular weight polyethylene fiber cable [6], to prevent femoral cracking did not produce any adverse effects, such as diminished femoral diameter. Furthermore, this method did not interrupt further reimplantation surgery as the configuration of the proximal femur was conserved (Fig. 3).

At present, the choice of stem retention or extraction in patients facing any of a variety of problems associated with well-fixed extended porous-coated stems is based on a number of different treatment strategies employed to resolve these problems. Indeed, even in cases of periprosthetic infection, hip surgeons tend to retain the well-fixed extended porous-coated stem because of difficulties associated with its extraction [7] and the potential for catastrophic failure, such as comminuted femoral fracture, when violent extraction methods are used. However, periprosthetic infection, in which a biofilm [8] may be produced, can be difficult to resolve. Furthermore, in cases of ARMD, tissue necrosis might spread, with allergic reactions to CoCr ions resulting in catastrophic failure; thus, removal of the CoCr element must be considered as the first treatment option [9, 10]. Minimal damage to the bone during the stem extraction process can make stem extraction possible even in these severe situations.

Limitations to this study are that not all patients underwent reimplantation surgery and that only a small number of cases were analyzed. Further, this study was retrospective and did not have a control group.

In the reimplantation process, ETO required relatively longer stems that reached beyond the osteotomy to achieve initial stability of the stem. However, it was sufficient for the reimplanted stems to be shorter or equal in length to the extracted stem in the FLS procedure as the fixation reliably restored the integrity of the metaphysis. In the FLS procedure, cerclage wiring is speculated to be sufficient to prevent comminuted fracture as no large bone defects remain.

Although this technique allows the expansion of the metaphyseal–diaphyseal region of the proximal femur facilitating extraction of well-fixed extended porous-coated stems, the fact that fractures could not be prevented during operation indicated that there was learning curve of this surgical procedure. Even if this process was not sufficient to remove the stem, it is supposed that our procedure can easily be converted to conventional ETO that might be reliable to extract stems and avoid femoral fractures. This useful FLS procedure may allow the easy removal of well-fixed extended porous-coated stems and become an alternative method for the removal of all stems.