Local infiltration analgesia (LIA) is promoted as an effective treatment modality for pain control after total knee arthroplasty (TKA) (1). A mixture of drugs is used to provide a multimodal analgesic effect. Previous studies reported that the use of these drugs is safe. After we carefully implemented a LIA study protocol in our practice, concerns raised about patient safety with probably higher infection rates. This forced us to perform an interim analysis after the first 58 cases.

58 patients underwent a unilateral TKA with a standardised LIA protocol (2), which consisted of a mixture of ropivacaine, epinephrine, and triamcinolone acetonide. Complications, knee function and patient satisfaction scores were prospectively recorded during regular outpatient control.

Four patients (6.9%) presented with signs of periprosthetic joint infection (PJI) within two months after surgery. Baseline characteristics were similar between the infected and non infected group. All infections were treated with debridement and retention, and antimicrobial treatment was started. One patient who suffered an infection died during followup. At two years followup all implants could be retained. Knee function and KSS score were acceptable for the patients who suffered PJI.

There is no consensus on the combination of drugs used for LIA. The application of corticosteroids in LIA is reported to be safe (3), but arguable results about the injection of local corticosteroids around knee arthroplasty surgery in the past have raised suspicion in literature (4). Combined with our unacceptable high rate of PJI, we believe that the current body of evidence, with small heterogeneous series, does not support the safe use of corticosteroids in LIA.

Prosthetic joint infections (PJI) caused by Streptococcus species are relatively common.

The aim of our study was to assess outcome after treatment for early and late PJI with Streptococcus species after a follow-up of two years.

For this study we retrospectively included all patients with primary or revision total knee arthroplasty (TKA) or total hip (THA) arthroplasty, a minimum of two periprosthetic tissue cultures positive for Streptococcus species and a minimum follow-up of one year. According to international guidelines patients were classified as having early or late PJI. All patients with an early PJI were treated according to a standard treatment protocol, i.e. debridement and retention of the prosthesis, followed by adequate antibiotic therapy. Patients with late PJI underwent a debridement followed by adequate antibiotic therapy or joint revision. Patients’ hospital records were reviewed and we evaluated the status of the original prosthesis after an infection.

Forty cases were included; 24 early and 16 late PJI. For early PJI, open debridement was performed in all patients, after a mean of 19 (range: 9 – 80) days. At final follow-up 21 prostheses (88%) were still in situ and without clinical signs of infection. Eight cases (41%) of late PJI were successfully treated with debridement and retention. Nine patients (59%) underwent a one- or two-stage revision. At final follow-up 16 patients (100%) with late PJI had a prosthesis in situ. Streptococcus dysgalactiae species accounted for more than 50% of the early infections, followed by Streptococcus agalactiae with 30%.

In case of PJI with Streptococcus species open debridement and retention of the prosthesis should be performed followed by adequate and long-term antibiotic treatment. As expected, the retention rate for early PJI is much higher than that for late PJI.