Preoperative Planning and Preparation

Independent of surgeon experience, preoperative planning, team communication, and adequate preparation will determine the efficiency of femoral component removal. These steps cannot be overemphasized. The specific goal of preoperative planning is to anticipate and plan for the worst-case scenario during the revision procedure.

Every successful revision total hip procedure requires careful planning and templating based on preoperative radiographs obtained with high-quality equipment, and in sufficient view to demonstrate the pathology. For femoral component revision, an anteroposterior (AP) view of the pelvis and AP and lateral views of the femur are the minimum radiographs required for planning. The radiographs of the femur should include the entire prosthesis and the distal extent of any existing bone cement in the femur. Because revision usually requires a longer implant, it is best to have the entire femur included on radiographs to understand the normal curvature of the femoral shaft, the structural integrity of the bony cortex, and the shape and dimensions of the canal.

Radiographs and clinical history are ideally reviewed in a team conference. This conference should include all key personnel who will participate in the procedure. At a minimum, this will include the surgeon, the surgical assistants who will help during the procedure, and the implant representative. Preferably, the circulating staff, the scrub technician, and the anesthesia staff should be aware of the anticipated duration and complexity of the operation, the expected blood loss, and the need for special equipment, bone grafts, and intraoperative fluoroscopy.

Old femoral implants should be identified using stickers or operative reports from the previous operation. Experienced implant representatives can be a very good resource in accomplishing this. If there is any doubt whether the entire femoral stem will need to be removed, then proximal subcomponents specific to the stem design should be available, such as modular neck pieces and femoral heads compatible with the specific taper dimensions. The tools and equipment needed to remove the old femoral implant should be reviewed at this planning session, along with the stem design to be implanted, bone grafts, and other augments required for reconstruction.

Proper planning and communication are critical components of the revision procedure. A properly educated support staff and implant representative can communicate details of the procedure to the operating room staff and can contribute greatly to a smooth and efficient procedure. Details of the planning session should be captured in writing, preferably using a standard form, such that all members of the operative team have access to this information.

Tools and Specialized Equipment

Once the mode of fixation (i.e., cemented stem versus porous ingrowth) has been identified, the proper tools for the stem removal should be anticipated. With few exceptions the Moreland cemented and cementless revision sets (DePuy, Warsaw, IN) are sufficient for most femoral revision procedures. Similar sets of hand-held instruments are made by other implant companies and can be used with equally effective results..

In some cases, power tools may be necessary for safe femoral stem extraction, and representative examples are available from Anspach (Lake Park, FL) and Midas Rex (Fort Worth, TX). Special courses are available to teach surgeons the proper technique for using these high-speed, low-torque tools that are very useful in some revision THA procedures. Power oscillating and reciprocating saw blades in various small sizes can be used very effectively to quickly develop a plane between the proximal femur and the implant.

Ultrasonic tools are sometimes useful for removing cement from the intramedullary femoral canal. Specially designed tool tips convert electrical energy to mechanical energy that is concentrated at the cement mantle, thereby breaking it down. When cortical bone is contacted instead of cement, auditory and tactile feedback can prevent canal perforation. Because more force is required to break cortical bone than cement, the ultrasonic system is generally safe, and this has been validated clinically. Limitations include a learning curve and the expense of purchasing or renting the ultrasonic equipment. If the equipment is not available, alternatives to removing retained cement in the femoral canal include the use of hand tools, facilitated by an extended osteotomy of the femoral canal that can expose the entire cement mantle.

In some revision procedures the existing cement mantle may have separated from the femoral cortices and fragmented into loose pieces. In such situations, one removal strategy is to introduce new cement into the femoral canal that can bond to the old cement and remove it in 1- to 2-cm–long segments with an extraction rod anchored in the new cement mantle ( Fig. 40-1 ). If indicated, this strategy requires the availability of special equipment (SEG-CES, Zimmer, Warsaw, IN).

Removal of loose, fragmented cement located distally in the canal can be achieved mechanically or by using an alternative strategy shown here. New cement is introduced to secure a retraction instrument and capture old cement in the canal. The entire construct is then extracted from the femur once the cement hardens, bringing the old cement out of the canal.

Extraction tools that can help pull the femoral implant out of the canal include modular femoral head and neck detachment devices and femoral stem extractors. Universal femoral extractors for modular and nonmodular components and special extractors that insert into a hole in the prosthesis or fit tightly around the prosthetic femoral neck can greatly facilitate implant removal and save operative time. In addition to extractors, a set of long-handled bone punches with and without offset built into the instrument should be available to impact the stem against the collar (if any) and assist in stem extraction ( Fig. 40-2 ).

Long-handled bone punches with and without offset built into the instrument are essential for impacting the collar of the stem during extraction and for related uses in revision femoral surgery.

Surgical Approach

The surgical approach is typically determined by the surgeon’s preference. The most commonly used approaches in THA in the United States are the posterolateral and the direct lateral (modified Hardinge) approaches. The posterolateral approach usually permits better visualization of the posterior column and acetabular wall, but exposure of the proximal femur is equally satisfactory with either approach.

The greater trochanteric osteotomy (GTO) and the extended trochanteric osteotomy (ETO) provide increasing exposure and operative flexibility to facilitate femoral component removal while decreasing the risk of femoral canal perforation. These surgical approaches are particularly suitable for complex revision total hip surgery. Before attempting any revision total hip operation, the surgeon should be familiar with trochanteric osteotomy and the method of trochanteric reattachment. After femoral component removal, deficient bone in the trochanteric bed may necessitate trochanteric advancement to the distal femoral cortex and reattachment with a cable-grip system.

A variation of the trochanteric osteotomy is the sliding trochanteric osteotomy. This is an excellent technique that maintains the continuity of the vastus lateralis and the abductors while mobilizing both muscles with a bony segment of greater trochanter during revision THA. Despite the preservation of muscle continuity, the option of transposing and reattaching the osteotomized fragment to viable distal femoral cortex is preserved with this technique.

The ETO and its variations can be used in combination with either the posterolateral or the anterior approach to the hip joint if further femoral exposure is deemed necessary. The ETO involves an osteotomy of the lateral third of the femoral circumference in continuity with the greater trochanter. By elevating the osteotomized piece with the muscular insertions preserved, excellent exposure of the femoral canal can be achieved. Reattachment consists of cerclage fixation of the osteotomized fragment back into its anatomic bed using wires or cables.

Trochanteric osteotomy generally provides a commanding and extensile view of the femur and facilitates component and cement removal. Because individual cases can present unique challenges, the ETO is best reserved as an option to be used if component removal cannot be accomplished otherwise. An ETO is possible even with a sliding trochanteric osteotomy, if after the trochanteric slide the femoral stem cannot be removed.

Cementless Stem Removal

During preoperative planning, the status of bone ingrowth and location of bone ingrowth on a porous femoral stem should be critically assessed on radiographs. The classifications “stable,” “bone ingrown,” and “fibrous ingrown” are useful tools for evaluation of radiographs of an existing porous femoral stem.

If the stem is mechanically loose on radiographs or demonstrates motion between the implant and bone during surgery, removal is usually straightforward. Proximal bone overhang should be cleared, and a sharp disimpaction force applied with a bone punch against the stem collar or with a suitable stem extractor device. If the stem cannot be removed by this maneuver, then removal by disimpaction should be abandoned because repeated disimpaction of a stable stem can lead to a fracture of the femur. If the stem cannot be extracted, it is stable and must be approached as such.

For proper approach to a stable uncemented porous-coated femoral stem, complete exposure of the proximal femur should be followed by a stepwise approach. The goals are to expose the proximal femur by removing cement, overhanging trochanteric bone, and fibrous tissue in this location. Then, thin flexible osteotomes of various dimensions and shapes should be used to develop a plane between metal and bone starting at the proximal end ( Fig. 40-3 ). Small oscillating and reciprocating power saw blades can initiate this process, followed by a gentle, repetitive tapping in and out of the flexible osteotome. Aggressive hammering will result in bone perforation. The intent is to free up the implant proximally and as far distally as possible without splitting the femur. Medially and laterally around the proximal stem, thin U-shaped osteotomes can follow the contour of the implant. Once the implant is sufficiently freed up, a sharp impaction down into the femur can break up any remaining implant-bone bonding and facilitate extraction. If extraction is not successful, the bone-metal plane is again developed from proximal to distal, using thin osteotomes. This is a laborious process that requires patience, without shortcuts. Aggressive haste will complicate the procedure by producing multiple cracks in the proximal femur.

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