Acute septic arthritis of the knee can lead to joint damage or sepsis, if early diagnosis and treatment fail to occur, which includes drainage of the joint, adequate antibiotic coverage and resting of the knee. Classically, drainage of the knee was performed either with multiple aspirations or open arhtrotomy. The arthroscopic approach has becoming widely accepted, as it allows adequate drainage of the pus and debridement with partial or total sinovectomy of the joint.

The aim of this study was to evaluate the differences between arthroscopy and open arthrotomy in the clinical outcomes and rate of recurrence in patients with septic arthritis of the knee joint.

We reviewed patients with acute septic arthritis of the knee admitted in our center between January 2010 and December 2014. The criteria for diagnosis was report of purulent material when arhtrotomy or arthroscopy was performed or a positive culture of the joint fluid. Patients with recent surgery or documented osteomyelitis of the femur or tíbia were excluded.

We used the Oxford Knee Score (OKS) to classify the clinical outcomes in the end of follow-up, and registered the rate of recurrence in each group. The statistical evaluation of the results was performed using Student's t-test.

65 patients were treated during this period, 37 by an open arthrotomy through a lateral supra-patellar aproach, and 28 by arthroscopy through 2 standard anterior portals. All the patients were imobilized with a cast or orthosis in the immediate post-operation period for a mean period of 13 days in the arthrotomy group (8–15) and 9 days in the arthroscopy group (6–12) and received endovenous antibiotics for at least 10 days, followed by oral antibiotics for a mean total of 36 days in the the arthrotomy group (30–48) and 32 days in the arthroscopy group (22–36). The mean follow-up was 22 months in the arthrotomy group (8–28 months) and 18 months in the arthroscopy group (14–24). The mean OKS was 31 in the the arthrotomy group (21–39) and 35 in the arthroscopy group (25–44). There was 1 recurrence in the arthrotomy group and 1 recurrence in the arthroscopic group, both managed by knee arthrotomy.

Drainage is a key step in treatment of knee pyoarthrosis, either through an open or an arthroscopic approach. Both seem to be equally effective, with no significant statistical difference in terms of recurrence. The functional results tend to favour the arthroscopic approach, but with no statistical significance.

Acute septic arthritis of the knee may be a challenging diagnosis in the emergency department and must always be excluded in any patient with knee pain and local or systemic signs of infection. Arthrocentesis of the suspected knee is mandatory, since the analysis of the synovial fluid gives useful information like the white blood cell count (WBC)/mm3 or the polymorphonuclear cell percentage (PMP). These parameters will help the clinician to make the decision to drain the joint in the operation room, without having to wait for the culture or Gram stain, which may take several days to be available. The classical cutoff of 50,000 WBC/mm3 with more than 90% of PMP may fail to include all the septic arthritis of the knee, since significant variation have been described in recent years. The aim of this study was to evaluate the accuracy of WBC/mm3 and PMP in the synovial fluid in the diagnosis of acute septic arthritis of the knee.

We reviewed the clinical data of patients diagnosed with acute septic arthritis of the knee admitted in our center between January 2010 and December 2014, specifically the WBC/mm3 and the PMP of the synovial joint fluid. The criteria for diagnosis of an acute septic arthritis of the knee was report of purulent material when arhtrotomy or arthroscopy was performed or a positive culture of the joint fluid. The statistical evaluation of the results was performed using Student's t-test.

48 patients matched the inclusion criteria. The mean WBC/mm3 was 44.333 (14.610–182.640) and the mean PMP was 91,89% (86,4%–98,1%). 28 patients (58,33%) had a WBC/mm3 below 50.000 and 44 patients (91,67%) had a PMP above 90%, both with no statistical significance.

Knee arthrocentesis is mandatory in every patient suspected to have an acute knee pyoarthrosis, since the joint fluid analysis may show several abnormal findings. Our results show that a considerable number of patients may show a relatively low WBC/mm3 in the joint fluid in the presence of a knee pyoarthrosis. The PMP may be a better criteria, but again failed to achieve statistical significance, probably because of the low number of patients. The synovial fluid analysis alone is probably misleading in the diagnosis of an acute septic arthritis of the knee if the clinician is guided by the classical guidelines. The physical examination, medical history, laboratory and imagiologic tests are all key elements in this challenging diagnosis.

Knee joint infection after an ACL reconstruction procedure is infrequently but might be a devastating clinical problem, if not diagnosed promptly and treated wisely.

The results of functional outcomes in these patients are not well known because there aren't large patient series in the literature.

The objective of this study was to evaluate the prevalence and determine the adequate management of septic arthritis following ACL reconstruction and to assess the patient functional outcomes.

The authors conducted a retrospective multicentric analysis of septic arthritis cases occurring after arthroscopically assisted ACL reconstructions (hamstrings and BTB), in patients submitted to surgery between 2010 to 2014. The study reviewed patients submitted do ACL reconstruction, that presented objective clinical suspicion of joint infection, in post-operative acute and sub-acute phases, associated with high inflammatory seric parameters (CRP >=10,0, ESR>=30,0) and synovial effusion laboratory parameters highly suggestive (PMN >=80, leucocytes >=3000).

All this patients were treated with antibiotic empiric suppressive therapy and then directed antibiotherapy according to antibiotic sensitivity profile, then the patients were submitted to arthroscopic lavage procedure, without arthropump, but with debris and fibrotic tissue removal preserving always the ACL plasty. The functional outcomes analyzed were the Lysholm and the IKDC score.

Eleven (2.2 %) out of 490 patients analyzed in the sudy were diagnosed with a post-operative septic arthritis. The microbiologic exams showed coagulase-negative Staphylococcus was present in 5 patients (S. lugdunensis in 4 cases and S. capitis in 1 case), Staphylococcus Aureus in 2 patients (1 MSSA and 1 MRSA). In four patients, the micro-organism was not identified.

The studied patients had a mean follow-up of 28 ± 16 months, the Lysholm score was 74.8 ± 12.2, the IKDC score was 66.4 ± 20.5.

Functional outcomes in the control group were better than those obtained in the infected group.

(Lysholm score 88.2 ± 9.4 (NS); IKDC score 86.6 ± 6.8 (NS). All patients retained their reconstructed ACL. None of the patients relapsed or need other intervention because of ACL failure and chronic instability.

The prevalence of septic arthritis after an ACL reconstruction in this series was 2.2 %, slightly higher than other international series (0.14 to 1.7 %). Arthroscopic lavages along with antibiotic treatment showed to be a secure procedure and allowed the preservation of the ACL plasties, without infection relapse. But the functional outcomes after active intra-articular infection were largely inferior to those obtained in patients without infection, probably to uncontrolled and intense inflammatory local response.

Postoperative infection is a difficult complication affecting total hip arthroplasty. It is painful, disabling, costly and it lacks definitive treatment guidelines. Klebsiella spp. are uncommon causes of Total Hip Arthroplasty. The aim of this case report was to document an effective treatment algorithm for a multidrug resistant Klebsiella spp infection after THA.

We report a case of a 56-year-old male who has performed a THA in 2007 at our institution. After 4 admissions due to posterior hip dislocations it was performed an Acetabular Revision in May 2014. The periprothesic infection was suspected by delayed wound healing with inflammatory signals and both abnormal values of Erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP). The patient was submitted to two hip arthrocenteses, one before and the other after antibiotic therapy (EV). The intra-articular cultures revealed a Klebsiella Pneumoniae infection only carbapenem-sensitive.

We decided to performed a two-stage total hip arthroplasty revision approach.

After the First Acetabular revision, ESR and CRP were augmented. X-rays and CT scans were performed, but inconclusive for infection. The patient completed longterm ertapenem therapy after the results of intra-articular cultures.

We repeated arthrocentesis and the result was positive for the same bacteria.

After 3 months of the Acetabular procedure we performed a Girldstone. We continued with Ertapenem and after 4 months we performed a Total Revision Arthroplasty. Final intra-articular cultures were negative for infection and ESR and CRP were both normal.

After 5 months of follow-up the patient is pain-free and has good ROM.

The infection risk is greater with the number of revision surgeries. Our institution has good outcomes with 2-stage procedure for multi drug infections. The best diagnosis tools were ESR and CRP, and intra-articular cultures. Two-stage revision surgery is a good choice for multi-resistent infections, and proper indications must be followed.