Distal Femoral Replacement in an 86-Year-Old-Man with Culture-Negative PJI After Multiple Revision TKAs

From Grand Rounds from HSS: Management of Complex Cases | Volume 14, Issue 1

Case Report

An 86-year-old man with a history of bilateral total knee arthroplasty (TKA) and left revision TKA 3 years later due to aseptic loosening presented to HSS 2 years after that with knee instability and recurrent effusions. A revision to a hinged knee prosthesis was performed; 4 months later, the patient noted knee swelling, with fevers and chills, and was diagnosed with a Staphylococcus schleiferi periprosthetic joint infection (PJI). An incision and drainage with liner exchange was performed, and chronic antibiotic treatment commenced. After a breakthrough PJI after 3 years, he underwent 2-stage exchange with explantation and spacer insertion, followed by reimplantation 2 months later with distal femoral replacement (DFR) (Figure 1).

Figure 1: Radiographs of the left knee after re-revision TKA (A), after explantation and cement spacer insertion (B), and after reimplantation with distal femoral prosthesis (C, D).

Recurrent PJI suspected 2 months later was treated with IV vancomycin and then oral doxycycline, although cultures remained negative. The patient reported persistent swelling of the leg, but no fevers, chills, or wound issues. The left knee subsequently grew Aspergillus flavus a year later, treated with DFR reimplantation and soft tissue reconstruction by way of a medial gastrocnemius muscle flap. Nonetheless, the infection persisted, and a static antibiotic eluting hip-knee-ankle fusion nail spacer (Figure 2) was inserted, with continuous voriconazole treatment.

Figure 2: Postoperative EOS X-ray showing static antibiotic eluting hip-knee-ankle fusion nail spacer.

On examination, the patient walked with a cane but reported that his pain had subsided and he had no body aches, fever, chills, or knee swelling. The left knee demonstrated mild edema, with no erythema or signs of persistent infection. Left knee X-ray revealed well-positioned intramedullary hip-knee-ankle fusion nail without movement of the proximal or distal interlocking screws. Magnetic resonance imaging (MRI) revealed fluid surrounding the cement spacer, distending the joint capsule (Figure 3). Preoperative laboratory results included a white blood cell (WBC) count of 8.5/nL (neutrophils 67.5%, lymphocytes 15.7%), erythrocyte sedimentation rate of 58 mm/hr, and C-reactive protein of 2.2 mg/dL. Synovial fluid culture showed Aspergillus flavus infection of the multiply revised TKA. The patient could not perform activities of daily living with the fusion nail in place and was indicated for conversion to DFR.

Figure 3: Preoperative MRI showing bone marrow edema and joint fluid surrounding the cement spacer, distending the joint capsule 18 cm proximal to distal.

The hip-knee-ankle nail removal was performed through the prior medial gastrocnemius muscle flap. The soft-tissue envelope appeared inadequate, and extensive fasciocutaneous flap mobilization was performed. The cement block was resected and the nail removed percutaneously via the piriformis fossa. Sequential reaming and metaphyseal cone reconstruction of both medullary canals was performed. Bone loss of the tibial metaphysis warranted the use of a 21-mm cone. On the femoral side, a 15-mm cone and a 13 × 190 mm stem were assembled and inserted; a 12-mm polyethylene insert-and-hinge mechanism was placed and the knee reduced. The knee was stable to varus and valgus stress in extension, mid-flexion, and flexion. Complex closure was performed, with modified incisions in the extensor mechanism and in the lateral joint capsule. A customizable vacuum-assisted-closure dressing was applied.

At 6 weeks postoperatively, intraoperative cultures returned negative, and X-ray showed the implants to be in good position, with no complications (Figure 4), and the patient began long-term oral voriconazole therapy.

Figure 4: Plain anteroposterior (A) and lateral (B) radiographs 6 weeks postoperatively, showing implants in good position.

Discussion

Approximately 20% to 50% of PJI cases are culture negative, which can lead to misdiagnosis as aseptic failure of total joint arthroplasty [1,2]. One systematic review and metaanalysis [3] found the neutrophil-to-lymphocyte ratio to be affordable and accessible for early PJI detection, compared to biomarkers that may be elevated in extraarticular cases. More recently, reverse transcription–polymerase chain reaction (RT-PCR) and genetic sequencing have been suggested as sensitive tests, especially for culture-negative PJI [4].

Two-stage revision arthroplasty with an antifungal agent is considered the most successful approach for fungal PJI, but controversies exist. A systemic review of 164 fungal PJIs reported an 85% success rate [5]; a retrospective study of 26 fungal PJIs found a success rate of only 38.5% with a 2-stage approach [1]. Salvage procedures such as knee arthrodesis may be needed if the 2-stage technique fails to eliminate PJI, especially in cases involving severe bone loss, multiple surgeries, or soft-tissue problems. Intramedullary knee arthrodesis may be superior to an external fixator in rates of complications, revision, and loosening [6].

Primary skin closure may not be possible in patients after multiple revisions, especially those with draining sinus or skin necrosis requiring accessory mobilization incisions or vacuum-assisted closure dressings. A recent study of 43 PJI cases involving gastrocnemius flap found survival rates of 71% at 2 years and 63% at 5 years [7].

Multiple TKA revisions can cause bone loss at the knee, requiring placement of revision components at the metaphysis and use of endoprosthesis or cone/sleeve during reimplantation. Fractures around primary TKAs treated with cemented DFR have shown revision-free survival of 97% at 5 years [8].

This case of PJI necessitated a close working relationship between surgical and infectious-disease teams to suppress the bacterial and fungal load. A static spacer facilitated soft-tissue healing and reduced infection, and plastic surgery interventions provided soft-tissue coverage at the 3 most recent surgeries. Despite negative intraoperative cultures, the patient will need antimicrobial therapy for the rest of his life to ensure treatment success.

Authors

References

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