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Although there are numerous reports of septic pyogenic arthritis after arthroscopic anterior cruciate ligament (ACL) reconstruction, there is limited information regarding the outcomes of fungal infection. We determined the outcomes of six patients with mycotic infection after regular ACL reconstruction. There were four males and two females with a mean age of 33 years. We determined the number of procedures performed, bone loss originating to control infection, and final reconstruction in these patients. An average of five arthroscopic lavage procedures had been performed at the referring centers. Fungal infection was diagnosed based on pathologic samples; five infections were the result of mucormycosis and one was Candida. After final débridement, the mean segmental bone loss was 12.8 cm. All patients were treated with intravenous antifungal coverage and cement spacers before final reconstruction. At final followup, all patients were free of clinical infection. Three had reconstruction with an allograft-prosthesis composite, two with hemicylindrical allografts, and one with an intercalary allograft arthrodesis. Despite the extremely unusual presentation of this complication, surgeons should be aware of potential and catastrophic consequences of this severe complication after ACL reconstruction.
Level of Evidence: Level IV, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.
The online version of this article (doi:10.1007/s11999-009-0714-0) contains supplementary material, which is available to authorized users.
Arthroscopically assisted ACL reconstruction is a routine orthopaedic procedure with infrequent complications and effective results. Infection is a rare complication after this surgical intervention ranging from 0.3% to 1.70% and usually involving bacterial organisms [2, 5–8, 10, 11, 14–16]. Although it is an uncommon complication, sepsis of the knee after ACL reconstruction can have serious consequences [3, 16].
Fungal infections are often difficult to diagnose owing to their seemingly mild and insidious nature, but nonetheless can cause devastating consequences . One case of fungal destructive tibial osteomyelitis has been described after reconstruction of an ACL . There was an extensive area of necrotic bone leading to radical débridement and massive bone resection. Compared with a pyogenic infection, fungal infections produce few tissue reactions and usually progress through a more indolent course, leading to massive bone destruction [1, 9, 13].
We therefore analyzed the outcome of a group of patients with a mycotic infection after routine ACL reconstruction, with subsequent severe bone loss that needed to be treated with salvage operations. We describe the bone loss after fungal infection; we then describe the salvage operations to reconstruct the bone loss; finally, we questioned whether the infections could be eradicated.
We retrospectively reviewed all six patients treated at our institution for fungal infections after arthroscopic ACL reconstruction. All ACL reconstructions were performed in six different surgical environments at different hospitals by different surgical teams in different areas of the country. Reconstruction of the ACL was performed with hamstring autografts in five patients and bone-patellar tendon-bone autograft in one; no drainage was left in any patient. Femur hamstring fixation was accomplished with Bio-Transfix cross pins (Arthrex, Naples, FL) in two patients, a Transfix cross pin (Arthrex) in one, Rigid-fix pins (Mitek, Johnson & Johnson, Norwood, MA) in one, and a Cross-screw pin (Stryker, Kalamazoo, MI) in one. In all cases using hamstring autograft reconstructions, biointerference screws were used for tibial fixation. The bone-patellar tendon-bone graft was fixed with two nonabsorbable interference screws. There were six consecutive patients seen during a 10-month period. Four patients were men and the other two were women with a mean age of 33 years (range, 26–52 years). None of the six patients had comorbidities or immunodeficient disease. Infection symptoms began in the original institutions at a median of 14 days (range, 10–17 days) after the ACL reconstruction. An average of five arthroscopic débridements (range, 2–8) had been performed before patients were referred to our institution, where as a result of persistent symptoms, a fungal infection was suspected. Open débridement was performed at referring institutions in two patients. The mean time between the onset of infection and radical débridement performed at our institution was 84 days (range, 38–150 days). The minimum followup was 24 months (mean, 28 months; range 24–34 months).
On admission we obtained detailed medical history and blood analyses. All patients had persistent serous drainage from previous wounds (three from the proximal tibia and three from the distal femur). At initial presentation in our hospital, four patients had mild pain and two had severe pain and all had limited range of motion. Imaging studies including radiographs, MRI, and tomographic studies showed all patients had extensive areas of necrotic bone involvement.
We performed radical open débridement consisting of open arthrotomy with a medial parapatellar approach, synovectomy, removal of osteosynthesis implants and graft, curettage, and massive bone resection resulting from severe bone necrosis involving the distal femur (Fig. 1) or the proximal tibia (Figs. 2–4). Radical débridement was performed based on intraoperative findings. Extensive bone necrosis was observed; the bone initially was curetted, however, in four patients, the entire extension of the affected meta-epiphyseal region was completely necrotic, and massive resection was required. In the remaining two patients, the articular surface could be preserved after extensive curettage and partial resection of the affected bone. In three of the four patients (one tibia and three femurs) in which only one articular surface was preserved, the reconstructive procedure consisted of an allograft-prosthesis composite (Figs. 1, ,3).3). The remaining patient was the one treated originally in this series with a patellar tendon autograft (Table 1) and was referred to our institution with a previous resection of all extensor knee mechanisms owing to an apparently uncontrolled infection. This patient had reconstruction with an intercalary allograft arthrodesis stabilized with an intramedullary nail. A cement spacer was left in all patients to avoid articular collapse and obtain temporary joint stabilization.
Empiric antibiotic therapy included vancomycin and rifampicin and was started immediately after surgery but was suspended when fungal infection was evident and no evidence of bacterial infection was found.
Aerobic, anaerobic, mycobacterial, and fungal cultures were obtained from joint fluid, synovial lining, ACL graft, and bone. Samples also underwent histologic analysis. Histopathologic analysis of the débrided tissue showed chronic inflammation, bone necrosis, and the presence of nonseptated hyphae (Fig. 4) in all patients. Fungal cultures were available after an average of 25 days (range, 18–30 days) and showed the presence of five Rhizopus Microsporus (fungal specimens of the Mucorales type) and one Candida albicans. After frozen sections confirmed the presence of fungal infection, 1 mg/kg intravenous amphotericin B was administered per day for 6 weeks. Treatment for four patients’ was changed from amphotericin B to liposomal amphotericin after they showed evidence of renal toxicity.
All patients were seen postoperatively at 1 week, 2 weeks, 1 month, and then every month thereafter until final reconstruction. Plain radiographs were obtained at every visit beginning 1 month after surgery. The patients were followed with serial erythrocyte sedimentation rate and C-reactive protein laboratory tests.
We considered the infection eradicated when clinical and laboratory parameters were in normal values at least 2 months after ending antifungal therapy.
The mean bone loss was 12.8 cm long (range, 9.5–19 cm). As described, in two cases, both articular surfaces were preserved after radical débridement, and in four, only one surface was preserved (Table 1).
The mean time between radical débridement and the final reconstructive procedure was 9.5 months (range, 6–15 months). In the two cases (two tibias) with both articular surfaces preserved, bone reconstruction was performed combining fragmented bone allograft to fill the metaphyseal cavity and a hemicylindrical intercalary structural cortical allograft to reconstruct the cortex (Fig. 2). This additional strut allograft buttresses the affected bone segment and restored the physiologic load to avoid potential fractures resulting from abnormal cortical load transmission in patients treated with fragmented allograft alone (A supplemental video is available with the online version of CORR). It also allowed immediate partial weightbearing and contains the allograft chips in the bone.
At final followup, all patients were free of clinical evidence of infection. One patient needed arthroscopic débridement as a result of arthrofibrosis. The patient with the intercalary arthrodesis had nonunion develop at the proximal osteotomy that required an additional autograft and revision of the intramedullary nail. Four patients walked without the use of supports and two walked using a cane. Three patients could walk an unlimited distance and three had some limitations in walking. Two patients had no discernible limp, two had a minor limp, and two had a major limp. No patient returned to sports.
Septic arthritis after arthroscopic ACL reconstruction is a rare complication usually involving bacterial organisms [2, 3, 5–8, 10, 11, 14–16]. The reported incidence of infection after ACL surgery ranges from 0.3% to 1.70%, but fungal infections are rare. The primary objectives in the treatment of septic arthritis after ACL surgery are to protect the articular cartilage and to preserve the graft. Prompt specific antibiotic therapy is mandatory as part of the treatment. Given the limited information on fungal infections, we analyzed the outcome of six patients with a mycotic infection after routine ACL reconstruction, with subsequent severe bone loss. We described bone loss after fungal infection and salvage operations to reconstruct the bone loss, and asked whether the infections could be eradicated.
Our report includes only referred patients treated originally at other institutions, and because we do not know the total numbers of cases from these institutions, we could not determine the incidence of this type of infection. Because of the relatively low number of patients, we were not able to find risk factors in this group of immunocompetent patients.
Mycotic bone infection is uncommon and, more frequently, specimens involved are Blastomyces and Coccidiodes . Mucormycosis is an opportunistic infection caused by fungi of the order of Mucorales, usually Rhizopus, Mortierella, Absidia, or Mucor . These virtually always occur in patients with defects in host defenses and/or with increased presence of serum iron (diabetes, neutropenia, corticosteroids, bone marrow transplantation), although rare cases have been reported in apparently normal hosts . The classic site of presentation is the rhinocerebral region, but pulmonary, gastrointestinal, and cutaneous forms also have been described . The agents of mucormycosis are typically incapable of penetrating intact skin. However, burns, traumatic disruption, surgical injuries, or skin maceration enable the organism to penetrate into deeper tissues. The clinical hallmark of mucormycosis is angioinvasion resulting in thrombosis and tissue infarction/necrosis with hematogenous dissemination. Mucorales are rare in the hospital environment, but contaminated surgical dressings and tape have been implicated as sources of mucormycosis. In addition, bacterial infections do not exclude the possibility of a concomitant fungal contamination.
We identified only one reported case of fungal osteomyelitis after arthroscopic ACL reconstruction . The authors described a patient with reconstruction of the ACL with an autogenous bone-patellar tendon-bone graft that was complicated by mucormycosis infection. No massive bone resection was needed, but radical débridement and amphotericin therapy were indicated. After 1-year followup, the patient had varus deformity with good range of motion.
We report six cases of severe fungal osteomyelitis with devastating consequences after arthroscopic ACL surgery. All patients were immunocompetent and transferred to our institution from different sites around the country. Different techniques had been performed, and given the small numbers of cases, we could discern no relationship among surgical implants, reconstructive procedures, or commercial providers. The six cases ended with radical débridement and massive bone resection (mean, 12.8 cm) with a cement spacer in combination with antifungal therapy (amphotericin). At final followup, all patients had undergone reconstruction and were free of clinical infection. Three were treated with an allograft-prosthesis composite, two with a hemicylindrical allograft, and one with an intercalary allograft arthrodesis resulting from severe alteration of stability after bone and extensor mechanism resection performed at the referring institution.
Timely treatment for osteomyelitis resulting from mucormycosis seems crucial [1, 4, 9, 12]. The mild and insidious clinical presentation of this disease usually delays the diagnosis. The infection is relentlessly progressive with aggressive soft tissue compromise and bone destruction and may result in extremity amputation [4, 12] or death unless treatment with aggressive surgical débridement and antifungal therapy are initiated promptly. It is extremely important to maintain a high index of clinical suspicion and to aggressively pursue material for a diagnostic biopsy.
Despite the extremely unusual incidence of this complication, we believe orthopaedic surgeons should be aware of the potential and catastrophic consequences of this disease, even after apparently routine and simple ACL reconstruction.
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