Antibiotic Therapy for 6 or 12 Weeks for Prosthetic Joint Infection.

BACKGROUND: The management of prosthetic joint infection usually consists of a combination of surgery and antimicrobial therapy. The appropriate duration of antimicrobial therapy for this indication remains unclear. METHODS: We performed an open-label, randomized, controlled, noninferiority trial to compare 6 weeks with 12 weeks of antibiotic therapy in patients with microbiologically confirmed prosthetic joint infection that had been managed with an appropriate surgical procedure. The primary outcome was persistent infection (defined as the persistence or recurrence of infection with the initial causative bacteria, with an antibiotic susceptibility pattern that was phenotypically indistinguishable from that at enrollment) within 2 years after the completion of antibiotic therapy. Noninferiority of 6 weeks of therapy to 12 weeks of therapy would be shown if the upper boundary of the 95% confidence interval for the absolute between-group difference (the value in the 6-week group minus the value in the 12-week group) in the percentage of patients with persistent infection within 2 years was not greater than 10 percentage points. RESULTS: A total of 410 patients from 28 French centers were randomly assigned to receive antibiotic therapy for 6 weeks (205 patients) or for 12 weeks (205 patients). Six patients who withdrew consent were not included in the analysis. In the main analysis, 20 patients who died during follow-up were excluded, and missing outcomes for 6 patients who were lost to follow-up were considered to be persistent infection. Persistent infection occurred in 35 of 193 patients (18.1%) in the 6-week group and in 18 of 191 patients (9.4%) in the 12-week group (risk difference, 8.7 percentage points; 95% confidence interval, 1.8 to 15.6); thus, noninferiority was not shown. Noninferiority was also not shown in the per-protocol and sensitivity analyses. We found no evidence of between-group differences in the percentage of patients with treatment failure due to a new infection, probable treatment failure, or serious adverse events. CONCLUSIONS: Among patients with microbiologically confirmed prosthetic joint infections that were managed with standard surgical procedures, antibiotic therapy for 6 weeks was not shown to be noninferior to antibiotic therapy for 12 weeks and resulted in a higher percentage of patients with unfavorable outcomes. (Funded by Programme Hospitalier de Recherche Clinique, French Ministry of Health; DATIPO ClinicalTrials.gov number, NCT01816009.).

Cement Loaded With High-Dose Gentamicin and Clindamycin Reduces the Risk of Subsequent Infection After One-Stage Hip or Knee Arthroplasty Exchange for Periprosthetic Infection: A Preliminary Study.

BACKGROUND: The use of antibiotic-loaded acrylic cement for treating periprosthetic joint infections remains controversial. We hypothesized that the raw rate of surgical site infection (SSI) is lower after using cement loaded with high-dose gentamicin and clindamycin than after using cement loaded with standard-dose gentamicin for implant fixation during 1-stage hip and knee revision arthroplasty for infection. METHODS: One hundred seventy-one continuous patients operated by 2 experienced surgeons during a 2-year period were included in the study. All patients were followed for 24 months. The primary endpoint was the raw rate of SSI after 2 years of follow-up time. RESULTS: The raw rate of SSI after 2 years of follow-up time was significantly lower in the study group (13%) than in the control group (26%) (P = .03) with an odds ratio of 0.42 (P = .03). These SSIs were new infections rather than a recurrence/persistence of the initial infection. CONCLUSION: The cement used in the study group significantly reduced the risk of SSI relative to the cement used in the control group. Routine use of this high-dose dual antibiotic-loaded cement can be considered during 1-stage knee or hip revision arthroplasty for infection.

Routine one-stage exchange for chronic infection after total hip replacement.

PURPOSE: We hypothesized that a routine one-stage exchange for treatment of chronically infected total hip replacement (THR) will lead to (1) a higher rate of infection recurrence and (2) a poorer hip outcome than the published rates after two-stage exchange. METHODS: Sixty-five cases have been treated consecutively with one-stage exchange. All patients have been followed for a period of three to six years or until death or infection recurrence. RESULTS: The five-year rate for infection recurrence was 16%. The five-year survival rate for recurrence of the index infection was 8%. Forty-two percent of the hips had a good or excellent PMA score, and 46% a good or excellent OH score. CONCLUSIONS: Routine one-stage exchange was not associated with a higher recurrence rate and a poorer hip function than previously published series of two-stage exchange. Therefore, there is little support to choose two-stage exchange as the routine treatment for management of chronically infected THR.

High infection control rate and function after routine one-stage exchange for chronically infected TKA.

BACKGROUND: Many 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/PURPOSES: We asked whether a one-stage exchange protocol would lead to infection control rates and knee function similar to those after two-stage exchange. METHODS: We 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. RESULTS: Three 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. CONCLUSIONS: While 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.

Primary musculoskeletal hydatid cyst of the thigh: Diagnostic and curative challenge for an unusual localization.

Primary muscular echinococcosis is an uncommon localization of hydatid cysts. The nonspecific clinical presentation and possible post-therapeutic complications lead to problems for the diagnosis of this infection and the support of the patient. The authors describe an unusual case of double hydatid cyst of the vastus intermedius muscle. After a precise preoperative evaluation based on clinical, radiological and biological examinations, a surgical excision by pericystectomy combined with perioperative chemotherapy enabled the authors to treat the patient and to prevent postoperative complications. The diagnostic tools and the treatment of this particular type of echinococcosis are discussed.

L'échinococcose musculaire primaire est un foyer inhabituel des kystes hydatiques. La présentation clinique non spécifique et les complications post-thérapeutiques éventuelles peuvent s'associer à des difficultés à diagnostiquer cette infection et à soutenir le patient. Les auteurs décrivent un cas inhabituel de double kyste hydatique du muscle vaste intermédiaire. Après une évaluation préopératoire détaillée fondée sur des examens clinique, radiologique et biologique, les auteurs ont traité le patient en procédant à une excision chirurgicale par périkystectomie conjuguée à une chimiothérapie périopératoire, ce qui a permis d'éviter les complications postopératoires. Ils présentent également les outils diagnostiques et le traitement de ce type d'échinococcose.

Navigated non-image-based positioning of the acetabulum during total hip replacement.

We tested the hypothesis that the non-image-based navigation system used in our department was able to measure accurately the 3D positioning of the acetabular cup of a total hip replacement (THR) and to increase the accuracy of its implantation during THR. We studied 50 consecutive navigated implantations of a THR and compared the intra-operative measurement of the cup by the navigation system to the post-operative measurement by computed tomography (CT) scan. The mean difference between the navigated and CT scan measurements for cup inclination was 2 degrees . The mean difference between the navigated and CT-scan measurements for cup flexion was 4 degrees . These differences were significant but considered to be clinically irrelevant in most cases. A total of 73% of the cases were within the safe zone defined prior to the study. The non-image-based system used allows a precise orientation of the cup during THR.

Bone penetration of daptomycin in diabetic patients with bacterial foot infections.

OBJECTIVES: Daptomycin has shown clinical efficacy in diabetic foot infections (DFI). However, only limited data are available on its bone penetration in this particular population. The aim of this study was to determine daptomycin bone concentrations in patients with DFI undergoing surgery after multiple daptomycin infusions and to determine bone daptomycin inhibitory quotients (IQs) for the predominant gram-positive species involved in DFI. METHODS: Fourteen adult patients hospitalized with DFI treated with daptomycin and requiring surgical bone debridement and amputation were included in this single-centre prospective study. Daptomycin concentrations in serum and bone were determined by HPLC at steady state. Bone IQs were then calculated according to different minimum inhibitory concentrations (MICs; range 0.25-4mg/l) that are representative of the main MICs for Staphylococcus aureus, coagulase-negative staphylococci (CoNS), and Enterococcus sp populations. RESULTS: Residual and peak concentrations varied from 4.5mg/l to 39.9mg/l and from 31.8mg/l to 110.9mg/l, respectively. Bone daptomycin concentrations at the moment of surgery varied from 1.2mg/l to 17mg/l. Up to a MIC of 1mg/l, which is the epidemiological cut-off value (ECOFF) and breakpoint value for S. aureus and CoNS, all bone daptomycin IQs were positive. The highest bone IQs were observed with Staphylococcus species. Calculated bone IQs for Enterococcus species were often weak at MIC values near the ECOFF. CONCLUSIONS: Daptomycin penetrates bone well in patients treated for DFI. At an initially recommended dosage of 6mg/kg, bone concentrations are likely to be effective against staphylococcal infections and infections due to low-MIC Enterococcus.

Reproducibility of intra-operative measurement of the mechanical axes of the lower limb during total knee replacement with a non-image-based navigation system.

OBJECTIVE: The restoration of a normal mechanical axis of the lower limb following total knee prosthesis (TKP) depends on the accuracy of the intra-operative measurement of the femoro-tibial angle. We have studied the reproducibility of intra-operative measurement of the coronal mechanical femoro-tibial axis with the OrthoPilot (Aesculap, Tuttlingen, Germany) non-image-based navigation system. MATERIAL AND METHODS: A consecutive series of 20 TKP (Aesculap SEARCH Evolution prosthesis) implanted by the same surgical team of two senior orthopedic surgeons was analyzed. They used a non-image-based navigation system that allows the mechanical axes of the femur and tibia to be defined with a kinematic analysis. The operating surgeon and assistant surgeon performed the kinematic analysis twice and once, respectively, and measured coronal mechanical femoro-tibial angles in maximal extension and at 90 degrees flexion without varus or valgus stress. RESULTS: The mean intra-observer variation in the measurement of the coronal mechanical femoro-tibial angle in maximal extension was 0.1 degrees (SD = 0.7 degrees). The mean intra-observer variation in the measurement of the coronal mechanical femoro-tibial angle at 90 degrees of knee flexion was 0.2 degrees (SD = 0.6 degrees). The mean inter-observer variation in the measurement of the coronal mechanical femoro-tibial angle in maximal extension was 0.1 degrees (SD = 0.7 degrees). The mean inter-observer variation in the measurement of the coronal mechanical femoro-tibial angle in maximal extension was 0.0 degrees (SD = 0.6 degrees). There were no significant differences and a high correlation between all paired intra- and inter-observer measurements. CONCLUSION: This system allows high reproducibility of the intra-operative measurement of the mechanical axes of the lower limb by a non-image-based kinematic registration of the hip, knee and ankle centers.

Navigated non-image-based registration of the position of the pelvis during THR. An accuracy and reproducibility study.

The precise recording of the position of the pelvis is a prerequisite for total hip replacement (THR). The anterior pelvic plane is an accepted reference for determining the 3D pelvic orientation. We hypothesized that cutaneous palpation of this plane was accurate and reproducible. Ten consecutive navigated implantations of THR prostheses were studied. In each case, four palpations of both anterior iliac spines and the pubic symphysis were performed with a navigated stylus. The first palpation was made on actual bone contours through a skin puncture and was considered as the reference. The other three palpations were made over the intact skin as a normal intra-operative procedure. There was no significant difference between the pelvic orientations measured by the three cutaneous palpations, or between the orientations measured by transcutaneous palpation and the mean result with cutaneous palpation. Cutaneous palpation can be considered as a reliable technique for the definition of pelvic orientation during THR with the non-image-based system employed.

The rationale for navigated minimally invasive unicompartmental knee replacement.

Computer-aided systems have been developed recently to improve the precision of implantation of unicompartmental or total knee replacements. Minimally invasive techniques were developed to decrease the surgical trauma related to prosthesis implantation. However, there are concerns about loss of implant positioning accuracy with minimally invasive techniques. Minimally invasive instruments have been adapted for use with a typical 6-cm skin incision for unicompartmental knee replacement. We prospectively studied 60 patients who had minimally invasive navigated UKA and compared them with an earlier group of 60 patients who underwent open navigated UKA. We used an intraoperative non-image-based navigation system. Minimally invasive navigated implantation of a UKA did not reduce the radio-graphic accuracy of the implantation compared to open navigated implantation. There were no major complications and little change from the conventional navigated operating technique. Because we do not yet know if navigation influences function and long-term survival, our conclusions need to be confirmed on a larger scale.

Results of treatment of septic knee arthritis: a retrospective series of 40 cases.

We studied a consecutive series of 40 patients presenting a septic knee arthritis, with a mean age of 49 +/- 20 (range 19-81) years. The aetiologies were: 18 postoperative arthritis, 12 haematogenous infections, 7 arthritis following aspiration or infiltration, and 3 articular wounds. The most common organisms were Staphylococcus aureus and epidermidis (23 cases). Surgical procedures consisted in 20 arthroscopic debridements, 6 open debridements, 14 synovectomies. According to Gächter's classification, there were 8 stage I, 18 stage II, 11 stage III and 3 stage IV cases. Fifteen patients had to be reoperated after the index procedure at our institution: one open debridement, six open synovectomies, one open arthrolysis, one arthrodesis and six total knee arthroplasties (TKA). Final examination was performed after 22 +/- 26 (range 12-96) months. All cases were considered free of infection. Good functional result was present by 19/33 cases (excluding arthrodesis and TKA). The delay between the onset of symptoms and surgery was the major prognostic factor of success (P=0.023). This delay was correlated with Gächter's staging of the intra-articular lesions. The diagnosis of septic knee arthritis must be suspected at the early stage of the disease, and diagnostic joint aspiration must be immediately performed when the diagnosis is suspected. We suggest that the treatment should be more aggressive than generally advocated. Needle aspiration should be only performed at the very early stages. Arthroscopic debridement should be the routine treatment. Synovectomy should be considered even as a primary procedure when significant synovial hypertrophy is present (Gächter stage III and IV) or when a more conservative treatment did not lead to a fast improvement.

Coronal alignment of the lower limb.

BACKGROUND: The coronal alignment of the lower limb is important for knee reconstruction procedures. However, normal alignment is hard to define because of its wide variation among normal individuals. Our hypothesis was that the variation in the normal anatomy as assessed by radiography is greater than commonly accepted. METHODS: We performed anteroposterior long-leg radiographs on 100 Caucasian patients without any known knee abnormality, to determinate the femorotibial angle, coronal orientation of the distal femoral condyles, and coronal orientation of the proximal tibial condyles. All measurements were performed by the same experienced knee surgeon. RESULT: The mean values observed were close to the values commonly described in the Caucasian population. However, only 15-20% of the cases met the mean values of Moreland et al. (1987) for the individual items, and only 2 cases had the exact normal values. There was a wide variation for all angles measured, with a standard deviation higher than the mean value. INTERPRETATION: The variation in the lower limb axes is wider than commonly believed. There is a need for individual knee reconstruction which takes the specific knee axes of the patient to be operated into account.

Should plain X-rays be routinely performed after blunt knee trauma? A prospective analysis.

BACKGROUND: We tested the hypothesis that it was possible to decrease the number of performed x-rays after a knee trauma without delayed fracture diagnosis by using the Ottawa knee rules. METHODS: Patients had routine x-rays of the injured knee during the first stage of the study and selective x-rays during the second stage. All patients were followed up to 6 months after the trauma. RESULTS: 138 patients were included in the first stage; 57 had negative Ottawa criteria: no fracture was observed; following the Ottawa rules, 41% of the x-rays could have been avoided. 178 patients were included in the second stage; 63 patients had negative Ottawa criteria: no fracture was diagnosed during the whole follow-up; 35% of the x-rays have been avoided. CONCLUSIONS: Ottawa rules allowed decreasing the number of x-rays performed after a knee trauma by 35% with a sensitivity for a knee fracture detection of 100%.

Accuracy of implantation of a unicompartmental total knee arthroplasty with 2 different instrumentations: a case-controlled comparative study.

The accuracy of implantation is an accepted prognostic factor for the long-term survival of unicompartmental total knee arthroplasties (UKAs). We adapted the conventional instruments for tricompartmental total knee arthroplasty implantation, with intramedullary femoral and extramedullary tibial guiding rods, to a UKA implantation. A total of 52 patients in whom a UKA was implanted with this instrumentation were matched (using age, sex, body mass index, preoperative coronal mechanical femorotibial angle, and severity of preoperative degenerative changes according to Ahlback) with 52 patients operated with the alternative instruments. Accuracy of implant placement measured by radiography was improved significantly by the new instrumentation, but there was no difference in the survival rate or the clinical outcome after 5 years in both groups. No complication related to the new instrumentation occurred. Longer follow-up is required to determine the advantages and disadvantages of both techniques.

Unicompartmental knee prosthesis implantation with a non-image-based navigation system: rationale, technique, case-control comparative study with a conventional instrumented implantation.

The accuracy of implantation is an accepted prognostic factor for the long-term survival of unicompartmental knee prostheses (UKP). We developed a non-image-guided navigation system for UKP implantation without any extramedullary or intramedullary guiding device. The 30 patients operated on with the navigation system (group A) were matched to 30 patients operated on with the conventional technique (group B) using age, sex, body mass index, preoperative coronal mechanical femorotibial angle, and severity of the preoperative degenerative changes. All patients had a complete radiological examination in the first 3 months after the index procedure, with anteroposterior and lateral plain knee radiographs and anteroposterior and lateral long leg radiographs. Coronal femorotibial mechanical angle and both coronal and sagittal orientations of the femoral and tibial components were measured. There were no significant differences in the mean numerical values of all measured angles except for the sagittal orientation of the tibial component, with a significant excessive posterior tibial slope in group B. There was a significant increase in the rate of prostheses implanted in the desired angular range for all criteria except the coronal mechanical femorotibial angle in group A. An optimal implantation with all optimal items was obtained by 18 cases in group A and 6 cases in group B. Navigated implantation of a UKP with the used, non-image-based system improved the accuracy of the radiological implantation without any significant inconvenience and with little change in the conventional operative technique. The only inconvenience was a 20-min longer operative time. This improvement could be related to a longer survival of such implanted prostheses.

Low reproducibility of the intra-operative measurement of the transepicondylar axis during total knee replacement.

BACKGROUND: The transepicondylar axis is often used for positioning of the femoral component in knee replacement. METHODS: We studied the reproducibility of the intra-operative palpation of the transepicondylar axis for rotational alignment of the femoral component in 20 total knee replacement (TKR) implantations with a non-image-based navigation system. 2 surgeons defined the transepicondylar axis 3 times each without changing the reference plane. RESULTS: The angle between the reference plane and the transepicondylar axis was measured by the navigation system. The mean intra-observer ranges of variation were 5 degrees and 6 degrees for both surgeons, with a maximum of 15 degrees. The mean inter-observer range of variation was 9 degrees, with a maximum of 15 degrees. Variations occurred in either internal or external rotation. Intra-observer agreement was considered good for one surgeon and poor for the other. There was no agreement between the two observers. INTERPRETATION: To define the rotational alignment of the femoral component of a TKR according to the intra-operative palpation of the transepicondylar axis may not be as reproducible as expected. However, the exact effect of this variability on the outcome after TKR should be studied.