Gastrocnemius Flap Reconstruction in Single-Stage Re-Revision Total Knee Arthroplasty for Infection with Soft-Tissue Defects: A Limb Salvage Approach

Introduction

Periprosthetic joint infection (PJI) is one of the most devastating complications following total knee arthroplasty (TKA), often necessitating complex surgical interventions. However, the incidence of PJI remains relatively low, affecting approximately 1% to 3% of cases of TKA. The management of deep PJI typically extends beyond antibiotic therapy, requiring surgical interventions, such as debridement with implant retention, single-stage or 2-stage revision arthroplasty, and, in severe cases, resection arthroplasty, arthrodesis, or even amputation [1–4]. The 2-stage revision, which was first described by Insall et al in 1983, remains the benchmark for complex chronic PJI. It involves removing the implant, debriding infected tissue, placing an antibiotic cement spacer, administering at least 2 weeks of antibiotics, and later implanting a new prosthesis. Although this procedure is effective, the infection recurrence rate ranges from 9% to 28%. In some cases, a single-stage revision, in which debridement and re-implantation occur in 1 operation, is performed. For example, Bonanzinga et al reported reinfection rates as low as 9% in selected cases, while other studies, including large cohorts, have reported failure rates exceeding 28% in high-risk populations [2,4,5]. A newer approach gaining popularity is the modified single-stage “2-in-1” revision, which follows the same principles as the 2-stage procedure but involves implanting the new prosthesis during the same surgery, after redraping and using sterile instruments. Recent evidence suggests that single-stage revision demonstrates non-inferiority in selected cohorts, particularly in patients with well-defined pathogens, good soft tissue quality, and no sinus tracts (Table 1) [3–5]. Repeat 2-stage revisions for persistent or recurrent infection have lower success rates, with infection-free survival dropping to 43% to 72% at 5 years and a high risk of further complications, including amputation and mortality [6]. Soft tissue complications around the knee, particularly following TKA, present significant reconstructive challenges. These problems are often compounded by infection, which can lead to exposure of the prosthesis, bone, or patellar tendon and can threaten the viability and function of the limb. Infected wounds often require aggressive debridement, which can create large, complex defects with exposed hardware or bone. The main challenges include (1) achieving durable, well-vascularized coverage over the prosthesis or joint, (2) managing dead space and infection, and (3) selecting appropriate recipient vessels for microvascular reconstruction if needed, especially in previously traumatized or operated fields with subsequent damage to tissues typically used to cover defects in that area. Soft tissue management in infected TKA is complex and requires individualized, multidisciplinary planning [6,7]. Muscle local flaps remain the criterion standard for infected soft tissue, especially with exposed prosthesis or bone. They offer obliteration of dead space, enhanced blood supply to aid infection control and antibiotic delivery, and reliable, robust coverage. The gastrocnemius flap (medial or lateral head) is the most commonly used, especially for patellar, infrapatellar, and proximal tibia with tuberosity defects. It is reliable, easy to harvest, and effective for deep infection. Other local muscle flaps, including the astus lateralis and medialis advancement flap, reverse vastus lateralis flap, medial soleus flap and skin with subcutaneous flaps as “keystone” type, and perforator propeller flaps, can be used for specific defect locations or when gastrocnemius is unavailable. Prosthesis salvage rates are 75% to 85% in the context of infection and soft tissue reconstruction [6–10]. The aim of this case report is to illustrate the application of a modified single-stage re-revision in a complex PJI case with soft tissue loss. It also highlights the importance of thorough debridement aided by methylene blue staining and immediate soft tissue reconstruction using bilateral gastrocnemius muscle flaps as a limb salvage procedure.

Case Report

An 81-year-old male patient was treated at multiple medical centers between 2021 and 2022 before being referred to our institution. He initially underwent TKA in June 2020 using a press-fit condylar (PFC) Sigma posterior-stabilized implant. Five weeks postoperatively, he developed wound dehiscence. In July 2020, a first revision surgery was performed due to infection (no pathogen data available), and the patient underwent debridement, antibiotics, and implant retention. Due to persistent infection, a second revision was performed in October 2020. A single-stage revision was performed at that time, during which the implant was exchanged for a Link Endo-Model rotating-hinge prosthesis. In November 2021, the patient presented with a recurrent abscess and 2 cutaneous fistulas. Over the following year, he was transferred between several institutions, with above-knee amputation proposed as a potential solution. In March 2022, the patient was referred to our reconstructive center. On presentation, he reported severe knee pain, limited range of motion (15°–40°), and 2 persistent fistulas associated with a soft tissue defect (Figure 1). Imaging studies (X-ray, computed tomography [CT], and bone scintigraphy) were performed. Synovial fluid aspiration yielded Proteus mirabilis on culture. Laboratory test results revealed elevated C-reactive protein at 12 mg/L (institutional upper limit: 5 mg/L) and leukocyte count of 8200/mm3 (within the reference range). In May 2022, a modified single-stage re-revision arthroplasty was performed with soft tissue reconstruction. The procedure included radical debridement with complete excision of infected soft tissue and fistulous tracts. An important element of the treatment was the use of methylene blue, which stained the inflamed tissues and enabled radical debridement (Figure 2). The surgical field and instruments were exchanged mid-procedure to minimize contamination. A new Link Endo-Model prosthesis was implanted, and local antibiotic delivery was provided using calcium sulfate beads (Stimulan) loaded with gentamicin and vancomycin. Soft tissue coverage was achieved using medial and lateral gastrocnemius muscle flaps, supplemented with split-thickness skin grafts harvested from the contralateral lower limb. This provided robust, vascularized coverage of the prosthesis (Figure 3). Within 3 weeks after surgery, complete soft tissue healing was achieved. The patient underwent extended antibiotic therapy with intravenous ceftriaxone for 6 weeks. He regained full weight-bearing capacity, ambulated pain-free, and achieved a knee range of motion of 0° to 90°. Radiographs showed stable implant positioning without signs of infection. After 18 months of satisfactory function, the patient developed recurrent knee pain. Imaging (X-ray, CT, and bone scintigraphy) revealed prosthetic loosening suggestive of reinfection (Figure 4). Laboratory studies demonstrated mildly elevated C-reactive protein (13 mg/L), while other inflammatory markers remained within the reference range. Repeated joint aspirates consistently grew Proteus mirabilis. Importantly, due to the previously successful soft tissue reconstruction, there were no cutaneous defects or fistulas at this time. In August 2024, the patient underwent a repeat modified single-stage re-re-revision arthroplasty. The Link Endo-Model prosthesis was exchanged, and further radical debridement of bone and soft tissue was performed. The previously reconstructed gastrocnemius flaps provided reliable vascularized coverage and allowed safe surgical access without compromise (Figure 5). Healing of the soft tissue was again complete and uneventful. At the 12-month follow-up, the patient remained pain-free, ambulated with full weight-bearing, and maintained a range of motion of 0° to 80°. Clinical examination and laboratory test results show no signs of reinfection. Early results were promising, but given the prior reinfection at 18 months, extended surveillance beyond 24 months is necessary to confirm the durability and long-term success of the intervention. The most important achievement of the treatment was successful soft tissue coverage and preservation of the limb, allowing for safe approach through the previously reconstructed soft tissues.

Discussion

In the presented case, the patient underwent multiple revisions because of infection. Due to incomplete eradication, recurrent infection occurred, which led to extensive inflammatory infiltration of the soft tissues with the formation of fistulas and soft tissue defect. An essential treatment strategy in this case was the removal of the endoprosthesis and inflamed bone, and most importantly, the radical excision of the inflamed soft tissues along with the fistulas. Unfortunately, such an approach resulted in the creation of a significant soft tissue defect, which required reconstruction. Preservation of viable tissue is critical, as it provides the biological environment necessary for infection control and optimal healing. In this case, a single-stage revision was performed with local implantation of antibiotics (vancomycin and gentamicin) using the antibiotic carrier Stimulan Rapid Cure, along with soft tissue reconstruction, using the medial and lateral heads of the gastrocnemius muscle, and extended antibiotic therapy with intravenous ceftriaxone for 6 weeks. This approach allowed for coverage of the endoprosthesis with well-vascularized tissues, creating favorable conditions for healing. Functional recovery and infection control were maintained for 18 months following the initial re-revision. However, long-term success could not be sustained, highlighting the complexity of managing recurrent PJI. Several studies have compared single-stage and 2-stage revisions, indicating that infection eradication rates may be comparable between the 2 techniques. A meta-analysis by Kunutsor et al demonstrated no significant difference in reinfection rates between single- and 2-stage revisions, suggesting that single-stage procedures can achieve similar outcomes with fewer surgeries and faster rehabilitation [2]. Similarly, Pangaud et al emphasized that, for selected patients, single-stage revision offers comparable infection control with added benefits of reduced hospitalization, lower costs, and better patient satisfaction [6]. The treatment strategy is extremely important because repeat 2-stage revisions for persistent or recurrent infection have lower success rates, with infection-free survival dropping to 43% to 72% at 5 years and a high risk of further complications, including amputation and mortality [6]. Another study focusing on patients with multiple prior failed surgeries, including failed single-stage and 2-stage revisions, reported that single-stage revision with adjunct intra-articular antibiotic infusion achieved an infection-free survival of 87.6% at 7 years, suggesting that, while challenging, repeat single-stage revision can still be effective in selected cases, especially with enhanced antibiotic strategies [7]. An equally critical factor was the use of muscle flaps, particularly the medial and lateral heads of the gastrocnemius, to reconstruct the soft tissue defect. Muscle flaps not only obliterate dead space but also deliver enhanced blood supply, which is vital for infection eradication and antibiotic penetration [6–8]. In this case, well-vascularized muscle coverage enabled robust healing and provided a stable biological environment for the new implant. This treatment requires rapid assessment, early and aggressive debridement, and durable, contoured coverage. Special consideration should be given to the timing of the intervention [9]. After 18 months, prosthesis loosening and reinfection occurred; however, the previously reconstructed flaps allowed safe surgical re-entry without vascular compromise, in line with cohort studies reporting durable flap function during subsequent revisions [15,16]. Moreover, systematic reviews and meta-analyses emphasize the central role of muscle flaps, particularly the gastrocnemius, in improving infection control and outcomes in complex revision knee arthroplasty reconstructions [11,12].

A modified single-stage re-revision with extensive soft tissue reconstruction using the gastrocnemius muscle is rarely performed, and there are no comparative analyses between such cases and 2-stage revisions. In our opinion, this approach can offer a viable alternative to 2-stage revision in selected cases; however, further data with longer follow-up and comparative studies are required to confirm its efficacy. The key aspect of this treatment was limb preservation and achieving good coverage of the soft tissues surrounding the knee, to allow for the possibility of future surgical intervention if needed.

Conclusions

A modified single-stage knee re-revision with extensive bone and soft tissue eradication and simultaneous soft tissue reconstruction using gastrocnemius muscle flaps represented a viable option in this complex scenario. The infection management must be aggressive, involving complete removal of all unhealthy tissue, including both the bone and soft tissue. To ensure thorough debridement, methylene blue staining was used intraoperatively to highlight infected and non-viable tissues, aiding in precise excision. This strategy allows for a single-stage approach, and in the event of further revision, enables safe surgical re-entry through previously reconstructed skin-muscle flaps without risking vascular compromise or tissue necrosis. The presented case has certain limitations, but preliminary results are encouraging, with successful soft tissue coverage and healing, as well as infection control maintained at 12 months. However, given the patient’s previous reinfection at 18 months, extended surveillance beyond 24 months is essential to confirm the durability and long-term outcomes of this intervention.