Haematogenous prosthetic knee infections: Prospective cohort study of 58 patients.

BACKGROUND: Prosthetic joint infection (PJI) is a rare (incidence, 0.15% to 0.9%) but serious complication of knee arthroplasty. Haematogenous PJI of the knee (KhPJI) which accounts for 10% of cases, has been less studied than PJI due to other mechanisms. The primary objective of this study in patients with KhPJI of the knee was to determine the 2-year infection eradication failure rate after either exchange arthroplasty or arthrotomy/synovectomy/irrigation (ASI), combined with prolonged peri-operative antibiotic therapy, at a referral centre for complex osteo-articular infections. HYPOTHESIS: ASI within 2 weeks after symptom onset and one-stage exchange arthroplasty produce similar 2-year success rates in patients with KhPJI of the knee. MATERIAL AND METHODS: A prospective observational cohort study was performed in patients managed for PJI of the knee between 2003 and 2015. The primary outcome measure was the occurrence of a septic event or of KhPJI -related death during a minimum follow-up of 2 years. RESULTS: Of 265 patients with PJI after total knee arthroplasty, 58 (22.1%) had KhPJI with onset more than 3 months after the last arthroplasty procedure and were included in the study. Among them, one-third had immune deficiencies. The most common causative organisms were streptococci (n=25, 43%) and Staphylococcusaureus (n=20, 34%). The primary focus of infection was identified in only 64% of patients and was most often cutaneous (n=19, 33%) or dental (n=11, 19%). A septic event or KhPJI-related death occurred in 5/34 (15%) patients after one-stage exchange arthroplasty and 6/19 (32%) patients after ASI within 15 days after symptom onset (p=0.03). Patient characteristics, type of prosthesis, and causative organism were not significantly associated with failure to eradicate the infection. CONCLUSION: ASI carried a high failure rate despite being performed within 15 days after symptom onset. One-stage exchange arthroplasty seems to be the best surgical option, particularly as the exact time of symptom onset may be difficult to determine. Identifying and eradicating the primary focus of infection is crucial. LEVEL OF EVIDENCE: II, low-powered prospective cohort study.

Outcome of patients over 80 years of age on prolonged suppressive antibiotic therapy for at least 6 months for prosthetic joint infection.

OBJECTIVES: To describe elderly patients treated with prolonged suppressive antibiotic therapy for a prosthetic joint infection (PJI) in cases where the infected prosthesis could not be removed. METHODS: All patients aged ≥80 years with a documented PJI and treated with prolonged suppressive antibiotic therapy for more than 6 months were included retrospectively in this study. The following events were noted: failure including persisting infection, relapse, new infection, treatment discontinuation due to severe adverse events, and related death, and also unrelated death. RESULTS: Thirty-eight patients with a median age of 84 years (80-95 years) were included; there were 24 hip infections, 13 knee infections, and one shoulder infection. The main causative organisms were Staphylococcus aureus (39%) and Streptococcus agalactiae (16%). The most commonly prescribed antibiotics as prolonged suppressive therapy were penicillins. The median follow-up duration was 24 months; 60% of the patients were event-free at 24 months and were still on prolonged suppressive antibiotic therapy. Fifteen events (six failures and nine unrelated deaths) were observed. Hypoalbuminaemia, the presence of a sinus tract, and a staphylococcal PJI were associated with an increased risk of an event. CONCLUSIONS: Prolonged suppressive antibiotic therapy is an alternative therapy in elderly patients with PJI when surgery is contraindicated and when the bacteria are susceptible to well-tolerated oral antimicrobial therapy such as beta-lactams.

Doctor, what does my knee arthroplasty weigh?

The aim of this study was to compare the weight of the total knee arthroplasty (TKA) implants and the weight of the natural knee. A prospective study was conducted with two different brands of cemented primary TKA. During the procedure, we collected the removed bone, soft tissues and the post-implantation cement and weighed them all separately at the end. In both groups, the implants plus cement were significantly heavier than the removed bone and soft tissues. The average weight gained was 266.7 ± 35.1 g for group 1 and 279.1 ± 48.7 g for group 2. This significant local weight gained after TKA is a new parameter that should be taken into account for further studies and when creating new implants.