PRACTICE PEARLS: Using Cement Spacers in the Hip
Dr. Wayne Paprosky demonstrates his technique for constructing and implanting a cement spacer when a patient is undergoing 2-stage exchange for an infected total hip arthroplasty.
Although there has been some interest lately in 1-stage exchange for an infected total hip arthroplasty (THA), Wayne G. Paprosky, MD, FACS, continues to prefer 2-stage exchange for revision procedures in his patients.
And rather than use premade spacers, he also continues to prefer to construct the cement spacers for the first stage of the procedure himself, which he demonstrated during ICJR’s Instructional Course at the 9th Congress of the Chinese Association of Orthopaedic Surgeons.
These are the steps of his 2-stage exchange protocol:
- Perform a radical debridement of components and cement, making sure to remove all cement and debris. If necessary, use intraoperative X-ray to confirm all cement has been removed.
- Use 3 grams of vancomycin and 1 bottle of tobramycin per package of cement. The systemic effects of the antibiotic seem to be minimal, he said.
- To make the cement spacers, use a threaded Steinman pin for internal support and use a bulb syringe as a “mold” to create the femoral head.
- Do not use an articulating spacer in patients with severe bone loss of the acetabulum, as this may cause further bone loss, pelvic discontinuity, or dislocation.
- Keep these patients “touch-down” weight-bearing to protect the cement spacer, and advise them to follow general THA precautions to prevent spacer dislocation.
- Administer intravenous (IV) antibiotics for 9 to 10 weeks, checking the erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) level weekly. Continue to check the ESR and CRP after IV antibiotic treatment ends.
- Perform the second (reimplantation) stage at about 3 months after the first stage. For most patients, Dr. Paprosky prefers cementless femoral fixation. Cement fixation allows the use of antibiotics in the cement, but long-term results are better with cementless fixation in revision THA.
Many of these infected hips still have strong fixation and ingrowth of the femoral stem, Dr. Paprosky said. In his video demonstration, he showed how he uses an extended trochanteric osteotomy (ETO) from the posterior aspect of the femur to expose and remove these stems. An oscillating saw is used to interrupt the anterior and posterior interface, and then a Gigly saw is used to disrupt the medial interface. If the stem is still well-fixed distally, the stem can be cut and the distal piece extracted without having to extend the osteotomy.
Dr. Paprosky advised attendees to spend as much time on implant removal as they would on constructing and implanting the spacer.
“Have the tools available to remove an ingrown acetabulum,” he said. “You want to spare as much bone as possible when removing the implants so that you can use an articulating spacer and put In the new implant without difficulty.”
Dr. Paprosky then showed his preferred method for constructing the articulating spacer from inexpensive materials commonly available in the operating room:
- The bulb part of a bulb syringe is filled with cement to create the femoral head.
- A thick threaded K-wire is bent to match the shape of the component that was removed and is then covered in cement to a thickness matching the femoral canal.
- The end of the K-wire is inserted into the femoral head and cement is added to the “neck” of the spacer to complete the construct.
- A gauge is used as a final check to confirm that the thickness of the stem of the construct is a good fit for the femoral canal.
Before inserting the spacer, Dr. Paprosky further debrides and cleans out the femoral canal using 3 to 4 liters of irrigation to ensure that all old cement and debris have been removed. In addition, the rubber bulb used to shape the femoral head is removed from the spacer.
The cement spacer is inserted into the femoral canal, taking care to achieve the correct amount of anteversion. A reduction is then performed and the hip is brought through a range of motion.
The ETO is reattached using monofilament wires. Dr. Paprosky prefers monofilament wire as studies have shown the infection risk when using monofilament wire is equal to that of procedures done without an osteotomy. Dr. Paprosky advises against using cables for fixation in infection cases.
Finally, the wound is closed and the position of the cement spacer is confirmed with X-rays.
Click the image above to watch Dr. Paprosky’s presentation from ICJR’s Instructional Course at the 9th Congress of the Chinese Association of Orthopaedic Surgeons.