Post-arthroscopic septic arthritis of the knee. Analysis of the outcome after treatment in a case series and systematic literature review

Evaluation of Experimental and Clinical Efficacy on Surgical Debridement and Systemic Antibiotics Treatment for Early Knee Infection after Anterior Cruciate Ligament Reconstruction

Deep knee infection (DKI) after anterior cruciate ligament reconstruction (ACLR) is rare and challenging. The optimal treatment strategy for infection after ACLR remains controversial. This study aimed to investigate the optimal treatment for early infection after ACLR surgery. Rats with unilateral ACLR were injected with 3.0 × 10⁵ colony forming units (CFU) of Staphylococcus aureus in the knee joint for 7 days. Next, with surgical debridement (SD) and/or 21 days of antimicrobial (systemic vancomycin and oral rifampicin [SVR]) therapy, rats were euthanatized and samples harvested. We evaluated signs of infection by general postoperative conditions, serum inflammatory markers, microbiological counting, knee radiographs, micro-computed tomography (micro-CT), histologic staining, and scanning electron microscopy (SEM). Clinically, the data from 12 patients who suffered from DKI after ACLR were analyzed retrospectively. The DKI rats treated with SVR showed better outcomes in general postoperative conditions, serum inflammatory markers, microbiological counting, biofilm on the interference screw and graft, radiographic signs of periarticular osseous destruction, and inflammatory reaction in the joint tissues than those with SD treatment, while the DKI rats with SD and SVR administration showed the best outcomes. Rats which received SD and SVR administration had their S. aureus contamination completely eradicated. All patients treated with SD & SVR or SVR alone had effectively controlled knee infections and achieved good knee function outcomes in the 6 months after treatment, but one patient developed more serious knee infections. Therefore, surgical debridement combined with systemic antibiotics treatment could effectively eliminate S. aureus contamination in the DKI rat model and in patients after ACLR without affecting knee function. Treatment with systemic antibiotics could also control early DKI, which would be especially applicable in patients who could not tolerate surgery.

Post-operative septic arthritis after arthroscopy: modern diagnostic and therapeutic concepts

PURPOSE

Septic arthritis is a significant complication following arthroscopic surgery, with an estimated overall incidence of less than 1%. Despite the low incidence, an appropriate diagnostic and therapeutic pathway is required to avoid serious long-term consequences, eradicate the infection, and ensure good treatment outcomes. The aim of this current review article is to summarize evidence-based literature regarding diagnostic and therapeutic options of post-operative septic arthritis after arthroscopy.

METHODS

Through a literature review, up-to-date treatment algorithms and therapies have been identified. Additionally, a supportive new algorithm is proposed for diagnosis and treatment of suspected septic arthritis following arthroscopic intervention.

RESULTS

A major challenge in diagnostics is the differentiation of the post-operative status between a non-infected hyperinflammatory joint versus septic arthritis, due to clinical symptoms, (e.g., rubor, calor, or tumor) can appear identical. Therefore, joint puncture for microbiological evaluation, especially for fast leukocyte cell-count diagnostics, is advocated. A cell count of more than 20.000 leukocyte/µl with more than 70% of polymorphonuclear cells is the generally accepted threshold for septic arthritis.

CONCLUSION

The therapy is based on arthroscopic or open surgical debridement for synovectomy and irrigation of the joint, in combination with an adequate antibiotic therapy for 6-12 weeks. Removal of indwelling hardware, such as interference screws for ACL repair or anchors for rotator cuff repair, is recommended in chronic cases.

LEVEL OF EVIDENCE

IV.

Knee septic arthritis caused by α-hemolytic Streptococcus in a patient with a recent history of knee arthroscopy: a case report

Background

Arthroscopic partial meniscectomy is a common procedure in orthopedic practice. Infections are uncommon complications of this procedure with an incidence rate of 0,01% - 3,4%. Staphylococcus spp are the predominant causative agents in such cases. We present a case of knee septic arthritis caused by α-hemolytic Streptococcus.

Case presentation

A 22-year-old woman diagnosed with obesity (body mass index [BMI] 35 kg/m²) but with no other major comorbidities underwent an arthroscopic selective meniscectomy with administration of intravenous cefazolin for antibiotic prophylaxis. After an uneventful period of 2 months, the patient returned with pain, fever and a discharging sinus at the site of anterolateral arthroscopic portal. Blood tests and magnetic resonance imaging revealed osteomyelitis involving the tibial plate. Cultures of synovial fluid obtained from the knee and a pharyngeal swab yielded α-hemolytic Streptococcus. Five days later, the patient underwent arthroscopic debridement with partial synovectomy. Intraoperative specimens yielded α-hemolytic Streptococcus. The patient received intravenous piperacillin/tazobactam, followed by an associative regimen of amoxicillin and clindamycin with clinical, laboratory and instrumental evidence of symptom resolution.

Conclusion

The incidence of knee septic arthritis after arthroscopic partial meniscectomy is 0.01–3.4%. This infection is usually caused by Staphylococcus spp. and in rare cases by commensal bacteria, such as α-hemolytic streptococci, secondary to transient bacteremia. Screening of the colonized area is important to prevent possible transient bacteremia. Diagnosis is based on isolation of the causative organisms from synovial fluid cultures, and treatment comprises arthroscopic debridement with individualized systemic antibiotic therapy based on the results of an antibiogram.