Revision Total Hip Arthroplasty with a Modular Fluted Tapered Stem for a Periprosthetic Femoral Fracture.

Abstract

Background: As the number of primary total hip arthroplasty procedures performed each year continues to rise, so too do the number of complications, including periprosthetic femoral fracture^1-9. Vancouver B2 and B3 periprosthetic femoral fractures are difficult to treat because they require the surgeon to simultaneously manage a femoral fracture and gain new implant fixation. Fluted tapered stems have advanced the treatment of periprosthetic femoral fractures by providing immediate axial and rotational implant fixation distal to the fracture^10-18. Modular fluted tapered stems provide the added practical advantage of allowing length and anteversion adjustment after implantation of the distal fixation portion of the stem.

Description: In this technique, a modified extended trochanteric osteotomy incorporating the fracture is utilized to gain access to the loose femoral implant and femoral diaphyseal canal. The femoral diaphyseal canal is then sequentially reamed in 1-mm increments. A fluted tapered stem with the appropriate length, diameter, and axial and rotational stability is inserted into the canal. A proximal body is then chosen that establishes the appropriate leg length, femoral offset, and version. The final proximal body is engaged into the fluted tapered stem. Finally, the fracture is fixed around the implant with a combination of cables or wires.

Alternatives: Historically, implants such as extensively porous coated stems were utilized to treat Vancouver B2 or B₃ periprosthetic femoral fractures. Unfortunately, these implants were associated with high rates of failure and revision^7,9.

Rationale: The introduction of a fluted tapered stem provided a more reliable implant that achieves immediate axial and rotational stability. In addition, utilizing a fluted tapered stem allowed for a more soft-tissue-preserving approach to these complex injuries, in turn allowing the fracture to be reduced around the implant proximally with cerclage cables and or wires. Modular fluted tapered stems provide the additional advantage of allowing the surgeon to modify leg length, offset, and femoral version, independently of the fluted tapered stem. As a result of these unique advantages, these stems were introduced several years ago for the treatment of Vancouver B₂ or B₃ periprosthetic femoral fractures.

Expected outcomes: Contemporary series have demonstrated that the use of a modular fluted tapered stem leads to improved implant survivorship and clinical outcomes with lower complication rates for Vancouver B2 and B₃ periprosthetic femoral fractures^{1,10-12,14-19}.

Important tips: Template both the fluted tapered stem and proximal body preoperatively. The proximal body should be templated at the ideal hip center of rotation that appropriately restores leg lengths and offset. Template the fluted tapered stem so that it provides appropriate isthmic fit and bypasses the most distal extent of the fracture by at least 2 cortical diameters.Utilize a modified extended trochanteric osteotomy for your exposure in order to facilitate visualization of the fracture and to provide direct access to the femoral canal.Place a prophylactic cable prior to preparing the femur for the implant in order to help prevent iatrogenic fracture.Place a trial stem and obtain intraoperative anteroposterior and lateral radiographs in order to assess the position of the implants and the risk of anterior cortical perforation.When placing the final implants, be sure the fluted tapered stem has both axial and rotational stability.Reduce and fix the fracture after the final implants are placed and the hip is reduced.

Acronyms and abbreviations: AP = anteroposteriorMFT = modular fluted tapered (stem)ETO = extended trochanteric osteotomyTHA = total hip arthroplastyCT = computed tomographyPJI = periprosthetic joint infection.