Investigation of the pathogen-specific antibody response in periprosthetic joint infection.

PURPOSE: Periprosthetic joint infections (PJIs) are a very demanding complication of arthroplasty. Diagnosis of PJI and pathogen identification pose considerable challenges in clinical practice. We hypothesized that the pathogen-specific immune response to PJI reflects the infection process, provides clinically relevant information on disease course, and has the potential to further optimize antimicrobial therapy. METHODS: We conducted a prospective matched cohort pilot study with 13 patients undergoing two-stage septic revision arthroplasty (PJI patients) between 06/2020 and 06/2021, as well as 11 control patients undergoing one-stage aseptic revision arthroplasty (Non-PJI patients). Pre-, intra- and postoperative serum samples were collected at standardized time points. We developed a custom Luminex®-based quantitative bead-based suspension array (Infection Array; IA), and used it for simultaneous measurement of antibody specificities against 32 pathogens commonly associated with PJI in 267 serum samples. RESULTS: The IA was able to trace the dynamics of the pathogen-specific humoral immune response in all patients against PJI-related pathogens, prominently coagulase-negative staphylococci and streptococci. Pathogen-specific serum antibody titers declined in 62% of PJI patients over the course of treatment, while no changes in antibody titers were observed in 82% of Non-PJI patients during this study. Our serological data strongly suggested that antibody signatures reflect an immune response to microbial invasion. CONCLUSION: Our results provide insights into the pathophysiology of PJI and information on the individual disease courses. The IA is therefore a promising and novel serological tool of high resolution for monitoring the immunoproteomic footprints of infectious pathogens in the course of PJI.

[Minimally invasive periacetabular osteotomy for adult hip dysplasia]. / Minimal-invasive periazetabuläre Osteotomie zur Therapie der Hüftdysplasie des Erwachsenen.

OBJECTIVE: Performance of a periacetabular osteotomy (PAO) using a minimally invasive approach for three-dimensional correction of the acetabular position. INDICATIONS: Symptomatic developmental dysplasia of the hip in adolescents and adults. CONTRAINDICATIONS: Advanced osteoarthritis of the hip, incongruence of the hip joint surfaces. SURGICAL TECHNIQUE: A periacetabular osteotomy is performed via a minimally invasive approach. RESULTS: In total, 39 patients were followed up for 3.5 (3-4.5) years. The lateral center-edge angle of Wiberg increased significantly from 16.1° (7-24°) to 30.5° (25-37°) (p < 0.0001), the acetabular index changed from 13.2° (2-25.3°) to 2.8° (-3-13°; p < 0.0001). Mean duration of surgery was 88 (57-142) minutes. No major complications occurred.

Identification of risk factors for treatment failure of closed reduction and abduction bracing after first-time total hip arthroplasty dislocation.

INTRODUCTION: After a first-time total hip arthroplasty (THA) dislocation, a closed reduction followed by partial immobilization in an abduction brace is the recommended therapy. Despite modern abduction braces the success rate of conservative therapy is limited and evidence is scarce. The aim of this study was to identify risk factors for failure of conservative treatment after THA dislocation. MATERIAL AND METHODS: Eighty-seven patients, with conservative treatment of a first-time dislocation of a primary or revision THA, were included in this retrospective cohort study. Success was defined as a stable THA for a minimum of 6 months. Re-dislocation, open reduction or revision was defined as failure. The following risk factors were analyzed: gender, age, body mass index (BMI), ASA (American Society of Anesthesiologists) score, time of dislocation, head size, cup orientation, leg length, center of rotation and offset. RESULTS: Sixty-seven percent of all patients experienced a re-dislocation, despite standardized conservative therapy. A BMI ≥ 25 kg/m2, early THA dislocation, and low cup anteversion were associated with a statistically significantly higher risk for re-dislocation. None of the other risk-factors achieved statistical significance. A multifactorial risk-factor analysis was performed to assess whether a cup position outside of Lewinnek's safe zone in combination with gender, BMI and time to dislocation showed statistical significance for re-dislocation. Both BMI ≥ 25 kg/m2 and early dislocation showed a statistically higher failure rate. Cup position and gender were not significant. CONCLUSIONS: BMI ≥ 25 kg/m2, early THA dislocation and low cup anteversion were identified as significant risk factors for failure of conservative treatment with an abduction brace for first-time THA dislocation.

Developmental Hip Dysplasia Treated with Cementless Total Hip Arthroplasty Using a Straight Stem and a Threaded Cup-A Concise Follow-Up, At a Mean of Twenty-Three Years.

We previously reported the 9-year follow-up results of 121 cementless total hip arthroplasties (THAs) from 1990 to 1994 in 93 patients with developmental dysplasia of the hip (DDH). The present study reports the updated long-term results after a mean follow-up of 23 years. Fifty-seven patients (72 hips) were alive and available for follow-up. Since our previous report, nine THAs had been revised. The cumulative implant survivorship of any component was 87% (95% CI, 78-92%). The cumulative probability of not having aseptic cup loosening was 87% (95% CI, 77-93%) and there was no revision surgery for aseptic stem loosening. In three hips (5%), an exchange of the ball and liner due to polyethylene wear was performed after a mean of 12 years. This study demonstrates that cementless THA for DDH with restoration of the hip joint center provides excellent long-term durability.

Defining the Clinically Meaningful Outcomes for Arthroscopic Treatment of Femoroacetabular Impingement Syndrome at Minimum 10-Year Follow-up: The Timing of Surgery Is Crucial.

BACKGROUND: Arthroscopic treatment of femoroacetabular impingement syndrome (FAIS) has become a common procedure. However, meaningful long-term clinical outcomes have not been defined. PURPOSE: To define the minimal clinically important difference (MCID), substantial clinical benefit (SCB), and patient acceptable symptomatic state (PASS) for the modified Harris Hip Score (mHHS) at a minimum 10-year follow-up in patients undergoing arthroscopic treatment for FAIS and identify preoperative predictors for achievement of the MCID, SCB, and PASS. STUDY DESIGN: Case-control study; Level of evidence, 3. METHODS: A consecutive series of patients undergoing arthroscopic treatment for FAIS between 2007 and 2009 with a minimum 10-year follow-up was analyzed. Patient data included patient characteristics, radiographic parameters, and the pre- and postoperative mHHS and visual analog scale (VAS) for pain score. Paired t tests were used to compare the patient-reported outcome measures (PROMs). The MCID was determined by calculating half of the standard deviation, and SCB and PASS were calculated by the anchor method. Correlation and logistic regression analyses were conducted to identify predictors for the achievement of the MCID, SCB, and PASS. RESULTS: A total of 44 patients (27 men, 17 women) were included. The mean age and body mass index were 42.2 years (range, 16-67 years) and 22.3 kg/m2 (range, 16.76-29.78 kg/m2), respectively. The MCID, absolute SCB, net change SCB, and PASS of the mHHS were calculated to be 19.6, 90.1, 31.5, and 84.4 points, respectively. Preoperative symptom duration was identified as an independent predictor for the achievement of meaningful clinical outcomes. The median symptom durations for patients who achieved the MCID, absolute SCB, net change SCB, and PASS were 11.7, 9.1, 9.0, and 10.8 months, respectively. The median symptom duration for patients who did not achieve the MCID, absolute SCB, net change SCB, and PASS were 15.8, 17.4, 17.3, and 18.4 months, respectively. No other statistically significant correlations were found. CONCLUSION: The preoperative duration of symptoms was identified as an independent predictor for achievement of the MCID, SCB, and PASS. These findings can be helpful in accelerating the transition to surgical treatment of FAIS.

A New Rectus and Sartorius Sparing Approach for Periacetabular Osteotomy in Patients with Developmental Dysplasia of the Hip.

BACKGROUND: periacetabular osteotomy (PAO) is known as the gold standard surgical treatment in young adults with symptomatic hip dysplasia. With the aim of reducing soft tissue trauma, we developed a new rectus and sartorius sparing (RASS) approach. We hypothesized that this new PAO technique was equal regarding acetabular reorientation, complication rate, and short-term clinical outcome parameters, compared to our conventional, rectus sparing (RS) approach. PATIENTS AND METHODS: we retrospectively assessed all PAO procedures performed by a single surgeon between 2016 and 2019 (n = 239 hips in 217 patients). The cases in which the new RASS technique were used (n = 48) were compared to the RS cases for acetabular orientation parameters, surgical time, perioperative reduction of hemoglobin level, and length of hospital stay (LOHS). Inclusion criteria were a lateral center-edge angle (LCEA) <25° and osteoarthritis Tönnis grade ≤1. Patients with acetabular retroversion or additional femoral osteotomy were excluded. RESULTS: the mean patient age at the time of surgery was 29 years (14 to 50, SD ± 8.5). Females accounted for 79.5% in this series. The mean preoperative LCEA were 16° (7 to 24°, SD ± 4.4) and 15° (0 to 23°, SD ± 6) in the RASS and the RS group, respectively (p = 0.96). The mean preoperative acetabular index (AI) angles were 14° (2 to 25°, SD ± 4) and 14° (7 to 29°, SD ± 4.3), respectively (p = 0.67). The mean postoperative LCEA were significantly improved to 31° (25 to 37°, SD ± 3.5, p < 0.001) and 30.2° (20 to 38°, SD ± 4, p < 0.001), respectively. The mean postoperative AI angles improved to 2.8° (-3 to 13°, SD ± 3.3, p < 0.001) and 3° (-2 to 15°, SD ± 3.3, p < 0.001), respectively. There were no significant differences between the RASS and the RS group for surgical time, perioperative reduction in hemoglobin level, and LOHS. No blood transfusions were necessary perioperatively in either group. No major perioperative complication occurred in either group. We observed one surgical site infection (SSI) requiring superficial debridement in the RS group. CONCLUSION: the RASS approach for PAO showed to be a safe procedure with equivalent acetabular reorientation and equivalent clinical outcome parameters compared to the RS approach. Additionally, patients have fewer postoperative restrictions in mobilization with the RASS approach.

Transversus abdominis Plane Block for Improved Early Postoperative Pain Management after Periacetabular Osteotomy: A Randomized Clinical Trial.

Background: Patients undergoing periacetabular osteotomy (PAO) may experience significant postoperative pain due to the extensive approach and multiple osteotomies. The aim of this study was to assess the efficacy of the transversus abdominis plane (TAP) block on reducing opioid consumption and improving clinical outcome in PAO patients. Patients and Methods: We conducted a two-group randomized-controlled trial in 42 consecutive patients undergoing a PAO for symptomatic developmental dysplasia of the hip (DDH). The study group received an ultrasound-guided TAP block with 20 mL of 0.75% ropivacaine prior to surgery. The control group did not receive a TAP block. All patients received a multimodal analgesia with nonsteroidal anti-inflammatory drugs (NSAID) (etoricoxib and metamizole) and an intravenous patient-controlled analgesia (PCA) with piritramide (1.5 mg bolus, 10 min lockout-time). The primary endpoint was opioid consumption within 48 h after surgery. Secondary endpoints were pain scores, assessment of postoperative nausea and vomiting (PONV), measurement of the quality of recovery using patient-reported outcome measure and length of hospital stay. Forty-one patients (n = 21 TAP block group, n = 20 control group) completed the study, per protocol. One patient was lost to follow-up. Thirty-three were women (88.5%) and eight men (19.5%). The mean age at the time of surgery was 28 years (18-43, SD ± 7.4). All TAP blocks were performed by an experienced senior anaesthesiologist and all operations were performed by a single, high volume surgeon. Results: The opioid consumption in the TAP block group was significantly lower compared to the control group at 6 (3 mg ± 2.8 vs. 10.8 mg ± 5.6, p < 0.0001), 24 (18.4 ± 16.2 vs. 30.8 ± 16.4, p = 0.01) and 48 h (29.1 mg ± 30.7 vs. 54.7 ± 29.6, p = 0.04) after surgery. Pain scores were significantly reduced in the TAP block group at 24 h after surgery. There were no other differences in secondary outcome parameters. No perioperative complication occurred in either group. Conclusion: Ultrasound-guided TAP block significantly reduces the perioperative opioid consumption in patients undergoing PAO.

Osteoarthrosis, Advanced Age, and Female Sex Are Risk Factors for Inferior Outcomes After Hip Arthroscopy and Labral Debridement for Femoroacetabular Impingement Syndrome: Case Series With Minimum 10-Year Follow-Up.

PURPOSE: (1) To determine the cumulative survivorship using the endpoint of total hip arthroplasty (THA) correlated with osteoarthrosis (Tönnis grade ≤ 1 vs Tönnis grade > 1) at a minimum 10-year follow-up and (2) to identify risk factors for THA conversion. METHODS: This study examined 112 patients who underwent hip arthroscopy for femoroacetabular impingement syndrome (FAIS) between 2007 and 2009. The inclusion criterion was primary hip arthroscopy to treat FAIS with corresponding chondrolabral pathologies. The exclusion criteria were secondary hip pathologies, revision hip arthroscopy, or dysplasia. The mean follow-up period was 11 years. Cumulative survival was estimated by Kaplan-Meier analysis using the endpoint of THA. Risk factors for THA conversion were identified using a multivariate Cox proportional hazards model. RESULTS: Forty patients underwent THA. The cumulative survivorship rate at 11 years was 86% for patients with a Tönnis grade of 1 or less and 46% for those with a Tönnis grade greater than 1. Osteoarthrosis, advanced age, and female sex were associated with lower hip survival rates. In particular, the risk of THA conversion was 24% higher for patients with an advanced age at the time of surgery, 97% higher for female patients, and 133% higher for hips with a Tönnis grade greater than 1. CONCLUSIONS: The survivorship rate at a mean 11-year follow-up after arthroscopic FAIS therapy was 86.3% in the group with a Tönnis grade of 1 or less and 46.4% in the group with a Tönnis grade greater than 1. The presence of osteoarthrosis, advanced age, and female sex adversely affected the outcome. LEVEL OF EVIDENCE: Level III, retrospective comparative study.

Dealing with the COVID-19 pandemic in orthopaedics: experiences and procedure in Germany.

AIMS: The worldwide COVID-19 pandemic is directly impacting the field of orthopaedic surgery and traumatology with postponed operations, changed status of planned elective surgeries and acute emergencies in patients with unknown infection status. To this point, Germany's COVID-19 infection numbers and death rate have been lower than those of many other nations. METHODS: This article summarizes the current regimen used in the field of orthopaedics in Germany during the COVID-19 pandemic. Internal university clinic guidelines, latest research results, expert consensus, and clinical experiences were combined in this article guideline. RESULTS: Every patient, with and without symptoms, should be screened for COVID-19 before hospital admission. Patients should be assigned to three groups (infection status unknown, confirmed, or negative). Patients with unknown infection status should be considered as infectious. Dependent of the infection status and acuity of the symptoms, patients are assigned to a COVID-19-free or affected zone of the hospital. Isolation, hand hygiene, and personal protective equipment is essential. Hospital personnel directly involved in the care of COVID-19 patients should be tested on a weekly basis independently of the presence of clinical symptoms, staff in the COVID-19-free zone on a biweekly basis. Class 1a operation rooms with laminar air flow and negative pressure are preferred for surgery in COVID-19 patients. Electrocautery should only be utilized with a smoke suction system. In cases of unavoidable elective surgery, a self-imposed quarantine of 14 days is recommended prior to hospital admission. CONCLUSION: During the current COVID-19 pandemic, orthopaedic patients admitted to the hospital should be treated based on an interdisciplinary algorithm, strictly separating infectious and non-infectious cases.Cite this article: Bone Joint Open 2020;1-6:309-315.

[Hip-spine syndrome-current developments and state of the evidence]. / Hip-Spine-Syndrom ­ Aktuelle Entwicklungen und Evidenzlage.

The movements between the spine, pelvis and hip joints are coordinated to allow for a physiological balance of the upper body and the pelvis during sitting and standing. Degenerative changes or spondylodesis of the spine result in decreased pelvic mobility and can lead to increased rates of instability in the presence of total hip arthroplasty (THA). To reduce the risk of THA dislocation several authors have recently recommended functional radiographs of the spine and pelvis, as well as individual safe zones for THA components. The aim of this article is to summarize the current body of knowledge regarding the influence of spinopelvic alignment on THA and provide recommendations for everyday clinical practice.

Increased Synovial Inflammatory Markers in Aseptic Total Hip Arthroplasty Dislocation.

BACKGROUND: In cases of total hip arthroplasty (THA) dislocation, a synovial fluid aspiration is often performed to evaluate for periprosthetic joint infection (PJI). It is currently unclear how aseptic dislocation of a THA influences synovial fluid white blood cell (WBC) count and polymorphonuclear percentage (PMN%). The primary aim of this study is to investigate the influence of THA dislocation on synovial WBC count and PMN%. METHODS: Twenty-eight patients who underwent a synovial aspiration of a THA between 2014 and 2019 were identified and enrolled in our case-control study. Patients with an aseptic THA dislocation and synovial hip aspiration were matched against patients without dislocation, patients undergoing hip aspiration before aseptic THA revision surgery, and patients undergoing hip aspiration before septic THA revision surgery. RESULTS: Synovial WBC count was significantly increased in the dislocation vs aseptic THA revision group (P = .015), as well as between the septic revision group vs dislocation and aseptic THA revision group (both P < .001). The PMN% did not differ significantly between the dislocation and aseptic revision groups (P = .294). Mean C-reactive protein values were 12.4 ± 14.9 mg/dL in THA dislocation, 24.1 ± 37.7 mg/dL in THA without infection compared to 85.7 ± 84.9 mg/dL in THA infection group (P < .001). CONCLUSION: This study shows that THA dislocation has a significant impact on synovial WBC count in joint aspiration. Our data suggest that in the setting of THA dislocation, synovial WBC and PMN% may not be the best method to evaluate for PJI. Further research should be performed to establish new thresholds for these synovial inflammatory markers in the setting of THA dislocation and PJI. LEVEL OF EVIDENCE: Level III; retrospective trial.

Long-Term Survivorship of Total Hip Arthroplasty with Highly Cross-Linked Polyethylene for Osteonecrosis.

BACKGROUND: Osteonecrosis of the hip is the underlying etiology for 3% to 12% of total hip arthroplasties (THAs). Compared with patients who undergo THA because of osteoarthritis, those who do so because of osteonecrosis typically are younger, have a greater number of underlying diagnoses, and have inferior clinical outcomes and implant survivorship. The purpose of this study was to compare the long-term implant survivorship (median follow-up, 10 years), functional outcomes, and radiographic results of contemporary THAs with a highly cross-linked polyethylene (HXLPE) liner between patients with osteonecrosis and those with osteoarthritis. METHODS: All patients who underwent primary THA with an HXLPE liner from 1999 to 2007 were identified from our institutional total joint registry. Patients with a primary diagnosis of osteonecrosis were matched 1:1, on the basis of age, sex, and body mass index (BMI), to patients with a diagnosis of osteoarthritis. This resulted in 461 hips in 413 patients with osteonecrosis matched to 461 hips in 427 patients with osteoarthritis (mean age, 59 years; 47% female; and mean BMI, 29 kg/m). Long-term implant survivorship, patient-reported outcomes, and radiographic findings were compared. In addition, a subgroup analysis of the osteonecrosis group was performed to see whether certain underlying etiologies portended poor outcomes. The median follow-up was 10 years. RESULTS: The 15-year cumulative rates of revision were 6.6% and 4.5% in the osteonecrosis and osteoarthritis groups, respectively (hazard ratio [HR] = 1.8, p = 0.09). The 15-year cumulative rates of any reoperation were 10.5% and 6.4% in the osteonecrosis and osteoarthritis groups, respectively (HR = 2.2, p = 0.008). There were no radiographic signs of component loosening or osteolysis in the entire cohort. Despite a lower median preoperative Harris hip score (HHS) for patients with osteonecrosis, both groups had marked improvements in their scores, which were similar at all time points after surgery. The cumulative rate of reoperations at 15 years was 0% for hips with radiation-induced osteonecrosis, 6.3% for those with alcohol-induced osteonecrosis, 9.0% for those with posttraumatic osteonecrosis, 12.1% for those with steroid-induced osteonecrosis, and 25% for those with idiopathic osteonecrosis. CONCLUSIONS: Contemporary THA with an HXLPE liner offers excellent long-term implant survivorship and functional outcomes for patients with osteonecrosis; however, the risk of a reoperation is higher when compared with patients with osteoarthritis. LEVEL OF EVIDENCE: Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Management of Chronically Infected Total Knee Arthroplasty With Severe Bone Loss Using Static Spacers With Intramedullary Rods.

BACKGROUND: Two-stage revision with static antibiotic spacers is the preferred treatment for chronically infected total knee arthroplasty (TKA) associated with severe bone loss. Intramedullary rods to reinforce static spacers have been described. On those, however, bacterial colonization may occur and hamper infection control. This study reports the microbiological findings on the spacer rods and the treatment outcome among these patients. METHODS: We reviewed 97 infected TKA with extensive bone loss treated with antibiotic-loaded cement spacers reinforced with intramedullary rods. Mean interim period with the spacer in situ was 9 weeks (range: 6-24 weeks). Intraoperative cultures and sonicated spacer rods were analyzed. Mean follow-up after TKA reimplantation was 41 months (range: 27-56 months). Treatment success was defined using the modified Delphi consensus criteria. RESULTS: Twenty-two patients (23%) had treatment failure, including 3 reinfections caused by the same organism, 9 reinfections caused by a different organism, 9 patients required interim spacer exchange, and 1 patient died in the early postoperative course. Sonication cultures of the spacer rods were positive in 2 cases (2%), and none of them failed. Host and limb status was significantly worse in patients who sustained reinfection. At the latest follow-up, all patients had a TKA in place, and 2 patients received chronic antibiotic suppression. CONCLUSION: Two-stage revision with the use of intramedullary rods is a safe and efficient treatment for chronically infected TKA with severe bone loss. Most reinfections grew different organisms compared with initial infection. Compromised hosts and extremities may be subjected to chronic antibiotic suppression.

Cerclages after Femoral Osteotomy Are at Risk for Bacterial Colonization during Two-Stage Septic Total Hip Arthroplasty Revision.

Aims: In cases of a two-stage septic total hip arthroplasty (THA) exchange a femoral osteotomy with subsequent cerclage stabilization may be necessary to remove a well-fixed stem. This study aims to investigate the rate of bacterial colonization and risk of infection persistence associated with in situ cerclage hardware in two-stage septic THA exchange. Patients and Methods: Twenty-three patients undergoing two-stage THA exchange between 2011 and 2016 were included in this retrospective cohort study. During the re-implantation procedure synovial fluid, periprosthetic tissue samples and sonicate fluid cultures (SFC) of the cerclage hardware were acquired. Results: Seven of 23 (30%) cerclage-SFC produced a positive bacterial isolation. Six of the seven positive cerclage-SFC were acquired during THA re-implantation. Two of the seven patients (29%) with a positive bacterial isolation from the cerclage hardware underwent a THA-revision for septic complications. The other five patients had their THA in situ at last follow-up. Conclusions: Despite surgical debridement and antimicrobial therapy, a bacterial colonization of cerclage hardware occurs and poses a risk for infection persistence. All cerclage hardware should be removed or exchanged during THA reimplantation.

Validation of CT image-based software for three-dimensional measurement of acetabular coverage profile.

BACKGROUND: Plain radiography, 2-dimensional (2D) magnetic resonance imaging (MRI), and computed tomography (CT) do not precisely display morphology and acetabular coverage in developmental dysplasia of the hip or pincer-type femoroacetabular impingement. Pelvic position and pelvic tilt affect assessment of the acetabular parameters, leading to misinterpretation. OBJECTIVE: We tested a 3-dimensional (3D) CT evaluation script to calculate the crossover sign (COS), acetabular coverage and morphology. METHODS: To test the method, we constructed a phantom pelvic model, in which the acetabulum was mounted at different coverages of the femoral head, and simulated a COS and the acetabular morphology. Additionally we examined the reliability and objectivity of this method in ten patients with CT scans of the pelvis for conditions unrelated to hip disorders. RESULTS: We obtained an average accuracy of the 3D CT evaluation script of -0.37∘ (range -3.84 to 3.88; SD ± 1.43) for morphology, and 0.002% (range -7.28% to 6.90%; SD ± 1.60%) for coverage of the femoral head. Significant correlation between the expected and calculated COS (p= 0.01) was found. CONCLUSIONS: Our 3D CT evaluation script permits precise evaluation of the acetabular coverage profile, the presence or absence of a COS and acetabular morphology, independent of patient positioning or pelvic tilt.

Reduced culture time and improved isolation rate through culture of sonicate fluid in blood culture bottles.

BACKGROUND AND OBJECTIVE: The aim of this study was to investigate if the cultivation of sonicate fluid (SFC) in blood culture bottles (BCB) leads to a higher rate of bacterial isolations than agar plate culture (APC) and to investigate whether the utilization of BCB leads to a reduction in culture time. METHODS: We performed a retrospective analysis of 206 revision total knee and total hip arthroplasty patients comparing the results of both synovial fluid culture and SFC in both BCB and conventional APC. RESULTS: The use of BCB improved both the rate of positive bacterial isolations and reduced the culture time for synovial fluid as well as SFC. Fifty-one patients showed a bacterial isolation in SFC-APC and 101 in SFC-BCB. For synovial fluid 24 patients showed a bacterial isolation on APC and 37 showed a bacterial isolation in BCB. The synovial fluid cultures showed growth on APC after an average of 2.8 days vs. 1.8 days in BCB. The SFC-APC showed growth after an average of 4.2 days vs. 2.9 days for SFC-BCB. CONCLUSIONS: The culture of synovial and sonicate fluid in BCB leads to more positive bacterial isolations and quicker bacterial growth than conventional agar plate cultures.

Inadequacy of Joint Aspiration for Detection of Persistent Periprosthetic Infection During Two-Stage Septic Revision Knee Surgery.

Despite the lack of validation, synovial aspiration remains a common practice during 2-stage septic revision total knee arthroplasty (TKA). The goal of this study was to investigate the diagnostic validity of synovial polymethylmethacrylate (PMMA) spacer aspiration of temporary knee arthrodesis to detect persistent periprosthetic joint infection before TKA reimplantation. This retrospective cohort study included 73 consecutive patients who underwent 2-stage septic revision TKA according to a standard protocol. After explantation surgery, including temporary arthrodesis with an intramedullary stabilized PMMA spacer, all patients had synovial aspiration 2 weeks before reimplantation to exclude persistent periprosthetic joint infection. Patients had a 2-week antibiotic holiday before aspiration. Sensitivity and specificity of the synovial PMMA spacer joint aspiration for the detection of periprosthetic joint infection were determined and referenced against intraoperative microbiologic and histologic samples obtained at second-stage surgery. Sensitivity of the synovial PMMA spacer aspiration was 21%. Because of poor diagnostic validity, synovial PMMA spacer aspiration cannot be recommended for routine exclusion of persistent periprosthetic joint infection before TKA reimplantation. Therefore, exclusion of persistent periprosthetic joint infection should be supplemented by other diagnostic methods, and it is not necessary to delay TKA reimplantation for PMMA spacer aspiration. [Orthopedics. 2017; 40(4):231-234.].

Increased rate of bacterial colonization on PE-components in total joint arthroplasty: An evaluation through sonication.

BACKGROUND: It is currently unclear if an isolated exchange of the mobile components, in cases of periprosthetic joint infection (PJI), leads to a complete eradication of all bacteria or if residual bacteria remain attached to the retained components? OBJECTIVE: The purpose of this study was to investigate if bacteria only adhere to certain components or materials, or if they are ubiquitously distributed throughout the joint. METHODS: Twenty hundred and eighty four patients undergoing revision total hip or total knee arthroplasty surgery were included in this retrospective cohort study. Synovial fluid cultures, periprosthetic tissue cultures, histological samples and sonicate fluid cultures (SFC) from the individual endoprosthetic components were acquired. The isolated bacterial species were recorded according to their endoprosthetic component of origin. RESULTS: In 72% of all cases with multiple SFC, the cultures were concordant with all samples being either homogenously negative or showing positive bacterial growth. The polyethylene (PE) components showed a significantly higher rate of bacterial isolation than the non-mobile components. All components and materials showed bacterial colonization, however between all other components or materials were not statistically significant. CONCLUSIONS: PE-components show a higher rate of bacterial isolation than other components. If an isolated bearing exchange is performed this should be supplemented by adequate antimicrobial therapy.