Jeannot Gaudias

High Infection Control Rate and Function After Routine One-stage Exchange for Chronically Infected TKA

BackgroundMany surgeons consider two-stage exchange the gold standard for treating chronic infection after TKA. One-stage exchange is an alternative for infection control and might provide better knee function, but the rates of infection control and levels of function are unclear.Questions/PurposesWe asked whether a one-stage exchange protocol would lead to infection control rates and knee function similar to those after two-stage exchange.MethodsWe followed all 47 patients with chronically infected TKAs treated with one-stage exchange between July 2004 and February 2007. We monitored for recurrence of infection and obtained Knee Society Scores. We followed patients a minimum of 3 years or until death or infection recurrence.ResultsThree of the 47 patients (6%) experienced a persistence or recurrence of the index infection with the same pathogen isolated. Three patients (6%) had control of the index infection but between 6 and 17 months experienced an infection with another pathogen. The 3-year survival rates were 87% for being free of any infection and 91% for being healed of the index infection. Twenty-five of the 45 patients (56%) had a Knee Society Score of more than 150 points.ConclusionsWhile routine one-stage exchange was not associated with a higher rate of infection recurrence failure, knee function was not improved compared to that of historical patients having two-stage exchange. One stage-exchange may be a reasonable alternative in chronically infected TKA as a more convenient approach for patients without the risks of two operations and hospitalizations and for reducing costs. The ideal one stage-exchange candidate should be identified in future studies.Level of EvidenceLevel IV, therapeutic study. See the Instructions for Authors for a complete description of levels of evidence.

C-reactive protein to transthyretin ratio for the early diagnosis and follow-up of postoperative infection.

Abstract The clinical usefulness of C-reactive protein (CRP) and of transthyretin (TTR) for the early diagnosis and follow-up of infection after an open fracture was prospectively investigated (cohort A). It was complemented by a retrospective study of trauma patients admitted to an intensive care unit (cohort B). Serial determinations of serum CRP and TTR concentrations were first performed in uninfected patients from cohort A to define a reference profile during the early postoperative period. It showed a concomitant increase in CRP and decrease in TTR concentrations, followed by progressive return to initial values in patients free from bacterial infection. Variations of the CRP/TTR ratio were analyzed. Recovery phase was defined by an exponential evolution of the two plasma proteins and of their ratio value. The CRP and TTR concentrations were independent of sex and severity of the trauma. In the case of postoperative infection, patients of cohort A revealed amplified CRP and TTR responses usually preceding the occurrence of clinical signs. During successful antibiotic therapy, their recovery response became superimposable to that of the reference group. The same profiles were recorded in cohort B patients admitted with lower limb fractures or various types of trauma. This suggests that observations made on cohort A can be extrapolated to other trauma patients. We recommend that serial measurements of CRP and TTR and of their ratio should be performed every 2 days to appropriately follow-up these patients.

Diagnostic value of C-reactive protein and transthyretin in bone infections of the lower limb

In a prospective study, white and red blood cell counts, hematocrit, erythrocyte sedimentation rate (ESR), albumin, alpha-1 acid glycoprotein, C-reactive protein (CRP), and transthyretin (TTR) values were determined by serial measurements during 23 days in 80 patients with an open fracture of the lower limb. Postoperative reference profiles were defined in 74 patients without septic complications. In the six remaining patients, serum CRP and TTR concentrations were found efficient for the early diagnosis of postoperative infections: a CRP/TTR mass concentration ratio higher than 0.6 from the 8th day after surgery was sensitive (100%) and specific (93%). Variations of CRP and TTR concentrations often preceded the clinical diagnosis in patients with early infection. ESR was found unreliable with regard to postoperative infection because of its high dependence with respect to red blood cell count.

Diagnostic accuracy of intra-articular C-reactive protein assay in periprosthetic knee joint infection – a preliminary study

BACKGROUND Periprosthetic joint infection often raises diagnostic challenges, as the published criteria are heterogeneous. New markers for predicting periprosthetic infection have been evaluated. Here, we assessed one of these markers, C-reactive protein (CRP), in joint fluid. HYPOTHESIS We hypothesised that intra-articular CRP levels would perform better than serum CRP concentrations in diagnosing knee prosthesis infection. PATIENTS AND METHODS We prospectively included 30 patients including 10 with native-knee effusions, 11 with prosthetic-knee aseptic effusions, and 11 with prosthetic-knee infection defined using 2011 Musculoskeletal Society criteria. Serum CRP was assayed using turbidimetry or nephelometry and intra-articular CRP using nephelometry. Appropriate statistical tests were performed to compare the three groups; P values < 0.05 were considered significant. RESULTS Serum and intra-articular CRP levels were 5- to 16-fold higher in the group with periprosthetic infection than in the other two groups. Although the areas under the ROC curves were not significantly different, the likelihood ratios associated with the selected cut-offs suggested superiority of intra-articular CRP: a value > 2.78 mg/L suggested possible infection (100% sensitivity and 82% specificity) and a value > 5.37 mg/L probable infection (90% sensitivity and 91% specificity). DISCUSSION Our findings suggest a possible role for intra-articular CRP assay in diagnosing knee prosthesis infection and perhaps periprosthetic infection at any site. LEVEL OF EVIDENCE Level III, diagnostic study, development of a diagnostic criterion in consecutive patients comparatively to a reference standard.

Incomplete or absent acute phase response in some postoperative patients.

In a prospective study, 74 patients were admitted for an open fracture of the lower limb and treated by osteosynthesis. None of them presented infectious complication during the postoperative period. Among them, 67 exhibited a classical acute phase response. In 5 patients, the response was apparently incomplete since no serum C-reactive protein (CRP) rise was observed after the injury; i.e. CRP concentrations remained inferior to the detection limit of the assay used; in contrast, serum alpha-1 acid glycoprotein (AAG) concentrations were temporarily increased, a variation associated with a concomitant decrease of transthyretin (TTR) concentration. In 2 other patients, CRP and AAG levels were not significantly modified. The 7 patients did not suffer hepatic insufficiency or protein malnutrition. In our series, incomplete or absent acute phase response was not rare (prevalence 9%) and was not related to an increased risk of postoperative infection. In contrast to CRP, the TTR response, i.e. a transitory decrease, was observed in all the 7 patients.

Agreement between pre-operative and intra-operative bacteriological samples in 85 chronic peri-prosthetic infections

BACKGROUND Whether pre-operative microbiological sampling contributes to the management of chronic peri-prosthetic infection remains controversial. We assessed agreement between the results of pre-operative and intra-operative samples in patients undergoing single-stage prosthesis exchange to treat chronic peri-prosthetic infection. HYPOTHESIS Agreement between pre-operative and intra-operative samples exceeds 75% in patients undergoing single-stage exchange of a hip or knee prosthesis to treat chronic peri-prosthetic infection. MATERIAL AND METHODS This single-centre retrospective study included 85 single-stage prosthesis exchange procedures in 82 patients with chronic peri-prosthetic infection at the hip or knee. Agreement between pre-operative and intra-operative sample results was evaluated. Changes to the initial antibiotic regimen made based on the intra-operative sample results were recorded. RESULTS Of 149 pre-operative samples, 109 yielded positive cultures, in 75/85 cases. Of 452 intra-operative samples, 354 yielded positive cultures, in 85/85 cases. Agreement was complete in 54 (63%) cases and partial in 9 (11%) cases; there was no agreement in the remaining 22 (26%) cases. The complete agreement rate was significantly lower than 75% (P=0.01). The initial antibiotic regimen was inadequate in a single case. DISCUSSION Pre-operative sampling may contribute to the diagnosis of peri-prosthetic infection but is neither necessary nor sufficient to confirm the diagnosis and identify the causative agent. The spectrum of the initial antibiotic regimen cannot be safely narrowed based on the pre-operative sample results. We suggest the routine prescription of a probabilistic broad-spectrum antibiotic regimen immediately after the prosthesis exchange, even when a pathogen was identified before surgery. LEVEL OF EVIDENCE IV, retrospective study.

Photo Quiz: Is Gardening Dangerous?

A 60-year-old female without any notable past medical or surgical history presented with redness, swelling, and pain at the base of her left fourth finger. Twelve hours before, she had cut the end of her finger with the tip of a pitchfork while mixing the compost in her garden. At the time of