Intramedullary Positive Tissue Culture Increases the Risk of Reinfection Following One-Stage Septic Revision Total Knee Arthroplasty.

BACKGROUND: Intraoperative acquisition of representative tissue samples is essential during revision arthroplasty of the infected total knee arthroplasty (TKA). While the number of intraoperative tissue samples needed to identify the organism is well described in the literature, there is still a paucity of evidence regarding the location of positive intraoperative samples and their correlation to postoperative outcomes. METHODS: There were forty-two patients who had septic failure following one-stage revision TKA for periprosthetic joint infection who were identified between January 2009 and December 2017. They were matched to a control group of patients who had successful one-stage revision TKA without septic failure. The location of positive intraoperative tissue samples was categorized as: 1) soft tissue; 2) interface between bone and prosthesis; and 3) intramedullary (IM). Chi-square, Student's t-, and Wilcoxon Mann-Whitney U-tests were used as appropriate. Univariate and multivariate logistic regression analyses were performed to evaluate predictors of septic failure. RESULTS: Weight > 100 kilograms (P = .033), higher Charlson Comorbidity Index (P < .001), and positive IM cultures (P < .001) were associated with a higher risk of reinfection after one-stage revision TKA. A positive IM sample carried a nearly five-fold increase in odds of reinfection (odds ratio 4.86, 95% confidence interval 1.85 to 12.78, P = .001). CONCLUSIONS: A positive IM culture sample is significantly associated with septic failure after one-stage exchange for periprosthetic joint infection of the knee. Patients who had positive IM cultures may benefit from longer postoperative antibiotic therapy for the treatment of one-stage exchange arthroplasty to minimize the risk of reinfection.

Anatomic Reduction of Greater Tuberosity Fragment for Shoulder Hemiarthroplasty: a Predictor of Good Clinical Outcome.

Objectives: Proximal humerus fractures account for four-five % of all fractures. Shoulder hemiarthroplasty is indicated for complex fractures with high complication rates when treated with ORIF. This study aims to evaluate the correlation between the proper intraoperative tuberosity reduction, and the mid-to-long-term clinical outcome in a series of patients treated with hemiarthroplasty after proximal humerus fracture. Methods: Forty-one patients with proximal humerus fractures who underwent hemiarthroplasty surgery between July 2009 and December 2019 were retrospectively reviewed. Quantitative analysis of the reduction of the tuberosities was performed on postoperative X-rays focusing on the distance between reconstructed greater tuberosity and the apex of the head of the prosthesis, (head-tuberosity distance), and contact between tuberosity and humerus diaphysis. The University of California Los Angeles Score (UCLA) was calculated for each patient. Results: The mean time to surgery was 6.29 ± 2.8 days (range 2-18 days). Nine patients out of 41 (22%) had non anatomic tuberosity, and 32 (78%) were anatomic reduced. The UCLA score at the final follow-up was good and excellent (≥27) in 27 patients (66%), and poor (<27) in 14 (34%). A significant correlation was observed between proper tuberosity reduction and good/excellent UCLA scores (P<0.001). Conclusion: Hemiarthroplasty is a valid and reliable technique for the treatment of proximal humerus fracture not eligible for internal fixation, with high risk of failure. The proper tuberosity reconstruction, paying special attention to the HTD and the contact between the cortical of the humeral diaphysis and the reconstructed tuberosity, is essential to reach a good clinical outcome.

The impact of sustentaculum tali fracture on clinical outcome in patients affected by isolated calcaneal fractures.

INTRODUCTION: The sustentaculum tali is displaced in almost half of calcaneal fractures and during surgical fixation represents one of the main reference points upon which the other bone has to be reduced. The purpose of this study was to investigate which subtalar joint fracture pattern is more frequently associated with sustentaculum tali involvement. Furthermore, correlation between postoperative clinical outcome and sustentaculum tali integrity was performed. MATERIAL AND METHODS: Patients with isolated calcaneal fractures were analyzed. Sanders-type fracture and involvement of both sustentaculum tali and calcaneocuboid joint were detected on computed tomography imaging; postoperative AOFAS scores were analyzed according to sustentacular involvement. RESULTS: Fifty calcaneus fractures in 47 patients were included in the final analysis. The sustentaculum tali was fractured in 18 cases (36.0%), thus contradicting its supposed constant position. Sanders type 3 and 4 fractures were more frequently associated with fractured sustentaculum than type 2 (p = 0.012). Sanders type 4 fractures were associated with displaced sustentacular fragment significantly more than type 2 and 3 (p = 0.043). Patients with intact sustentaculum tali reported significantly higher (p < 0.001) mean AOFAS scores than the uninjured group (84.4 ± 9.1 and 74.3 ± 9.5, respectively). CONCLUSION: Sanders type 3 and 4 fractures were more frequently associated with sustentaculum tali and/or calcaneocuboid joint involvement than simpler fractures. Injury of sustentaculum tali was related to significant worse postoperative clinical outcomes, underlying the relevance of this fragment on clinical course.

Accuracy of radiographic projections to guide cephalic screw position in pertrochanteric fracture: a cadaveric study.

PURPOSE: The aim of this study was to evaluate the relationship between the Löwenstein Lateral view and the True Lateral view for the positioning of the cephalic hip screw, through a cadaveric study. MATERIALS AND METHODS: We placed two Kirschner wires in eight femur specimens using an Antero-Posterior view, Löwenstein Lateral view and True Lateral view. The distances between the Kirschner wires and the anterior, posterior, superior and inferior cortex were measured in all projections. The head of the femur was then sectioned, and the same macroscopic distances were measured. Finally, we could calculate the accuracy of the two radiographic lateral projections. RESULTS: When the Kirschner wire was placed in the center of the head using the Antero-Posterior and the True Lateral view, the accuracy of Antero-Posterior view was 0.9705 while the accuracy of True Lateral view and Löwenstein Lateral view was 1.1479 and 1.1584, respectively. When the Kirschner wire was placed superior on the Antero-Posterior and centrally on the True Lateral view, the accuracy of Antero-Posterior view was 0.9930 while the accuracy of True Lateral view and Löwenstein Lateral view was 1.1159 and 0.7224, respectively. CONCLUSION: When the Kirschner wire was positioned proximal in Antero-Posterior view and central in True Lateral view, only the True Lateral view showed high accuracy.

A Novel Radiological Classification System of the Proximal Humerus.

Different anatomical variants have been reported for the proximal and distal femur. Given this context, the goal of our study was to answer the following question: Can we also identify different anatomical variants of the proximal humerus?Two hundred anteroposterior (AP) radiographs of the proximal humerus with an equal gender distribution and equal laterality per gender were reviewed. The metaphyseal diameter of the proximal humerus at the level of the anatomical neck (X) and the intramedullary diameter at 10 cm from the apex of the greater tuberosity (Y) were measured. A new ratio was established, based on both measurements (Y/X). Radiographs showed different anatomical variants: type A: Y/X < 0.3, type B: Y/X = 0.3-0.4, type C: Y/X > 0.4. Two observers reviewed the AP radiographs independently and blindly in 2 different sessions.Three different anatomical groups (A, B and C) were identified based on the 25th and 75th percentiles. A higher percentage of type C was observed among females and a higher percentage of type A among males. A high inter-observer reliability was noted, with a Cronbach's alpha of 0.97 (ICC 0.96-0.98). The intra-observer reliability for observer 1 had a Cronbach's alpha of 0.98.A novel radiological classification of the proximal humerus has been established based on 3 different anatomical types (A, B and C). Further studies are needed to establish whether the novel classification system can be used as an indicator for aseptic loosening of cemented or cementless total shoulder arthroplasty.

What Is the Most Reliable Concordance Rate of Preoperative Synovial Fluid Aspiration and Intraoperative Biopsy to Detect Periprosthetic Joint Infection in Knee, Hip and Shoulder Arthroplasty?

The accuracy of preoperative synovial fluid microbe detection in periprosthetic joint infection (PJI) is widely reported. However, the reliability of this diagnostic modality amongst the different joints is not yet described. We aimed to compare the concordance rate between preoperative synovial fluid and intraoperative tissue cultures in shoulder, knee and hip PJIs. A total of 150 patients who met the 2018 International Consensus Meeting criteria for shoulder, hip and knee PJI were retrospectively reviewed. This cohort was divided into three groups based on the involved joint (should, hip or knee), with 50 patients in each group. Cultures were collected and held for culture for 14 days. The overall concordance rate was 56.7%. Concordance rates between preoperative and intraoperative cultures were 60%, 56% and 54% for the knee, shoulder and hip joints, respectively. The analysis of high- or low-virulence and difficult- or not-difficult-to-treat germs did not reveal any significant differences between preoperative and intraoperative cultures in any of the groups. However, even considering the higher concordance in knee PJI, the overall discordance between preoperative and intraoperative cultures should prompt surgeons not to rely solely on preoperative synovial fluid culture data in determining appropriate treatment and antibiotics.

Setting the Tibial Component Rotation Based on Femoral Landmarks Allows Congruent Knee Kinematics in Robotic-Assisted Medial Unicompartmental Knee Replacement.

The accurate positioning of the prosthetic components is essential for achieving successful results in medial unicompartmental knee arthroplasty (mUKA). The tibial component rotation in image-based robotic-assisted UKA is usually based on tibial bony landmarks matched to the pre-operative CT model. The study aimed to evaluate whether setting the tibial rotation on femoral CT-based landmarks allows congruent knee kinematics. We retrospectively analyzed data from 210 consecutive image-based robotic-assisted mUKA cases. In every case, we set the tibia rotation landmark parallel to the posterior condylar axis and centered it on the trochlea groove defined on the preoperative CT scan. The implant positioning was primarily set parallel to this rotation landmark and then adjusted based on tibial sizes avoiding component over- or under-hang. During surgery, we recorded the knee kinematics under valgus stress to reduce the arthritic deformity. A femoral-tibial contact point was recorded over the entire range of motion and displayed as a tracking profile on the tibia implant. The femoro-tibial tracking angle (FTTA) was then calculated based on a tangent line to the femoro-tibial tracking-points and the difference to the femur-based rotation landmark. In 48% of the cases, we could position the tibia component exactly to the femoral rotation landmark, whereas in 52% of cases, minimal adjustments were made to avoid component's under- or over-hang. The mean tibia component rotation (TRA) with reference to our femur-based landmark was +0.24° (SD ± 2.9°). The femur-based tibia rotation landmark showed a high correspondence to the FTTA with 60% of the cases having less than 1° of deviation. Mean FTTA was +0.7° (SD ± 2.2°). The mean difference between the absolute value of the TRA and the FTTA (|TRA| - |FTTA|) was -0.18° (SD ± 2°). Setting the tibial component rotation based on CT scan femoral landmarks and not on tibial anatomical landmarks is a reliable method to obtain congruent knee kinematics during image-based robotic-assisted medial UKA with less the 2° deviations on average.

What is the Safe Distance Between Hip and Knee Implants to Reduce the Risk of Ipsilateral Metachronous Periprosthetic Joint Infection?

BACKGROUND: Periprosthetic joint infection (PJI), the most common cause of revision after TKA and THA, is a devastating complication for patients that is difficult to diagnose and treat. An increase in the number of patients with multiple joint arthroplasties in the same extremity will result in an increased risk of ipsilateral PJI. However, there is no definition of risk factors, micro-organism patterns, and safe distance between knee and hip implants for this patient group. QUESTIONS/PURPOSES: (1) In patients with hip and knee arthroplasties on the same side who experience a PJI of one implant, are there factors associated with the development of subsequent PJI of the other implant? (2) In this patient group, how often is the same organism responsible for both PJIs? (3) Is a shorter distance from an infected prosthetic joint to an ipsilateral prosthetic joint associated with greater odds of subsequent infection of the second joint? METHODS: We designed a retrospective study of a longitudinally maintained institutional database that identified all one-stage and two-stage procedures performed for chronic PJI of the hip and knee at our tertiary referral arthroplasty center between January 2010 and December 2018 (n = 2352). Of these patients, 6.8% (161 of 2352) had an ipsilateral hip or knee implant in situ at the time of receiving surgical treatment for a PJI of the hip or knee. The following criteria led to the exclusion of 39% (63 of 161) of these patients: 4.3% (seven of 161) for incomplete documentation, 30% (48 of 161) for unavailability of full-leg radiographs, and 5% (eight of 161) for synchronous infection. With regard to the latter, per internal protocol, all artificial joints were aspirated before septic surgery, allowing us to differentiate between synchronous and metachronous infection. The remaining 98 patients were included in the final analysis. Twenty patients experienced ipsilateral metachronous PJI during the study period (Group 1) and 78 patients did not experience a same-side PJI (Group 2). We analyzed the microbiological characteristics of bacteria during the first PJI and ipsilateral metachronous PJI. Calibrated, full-length plain radiographs were evaluated. Receiver operating characteristic curves were analyzed to determine the optimal cutoff for the stem-to-stem and empty native bone distance. The mean time between the initial PJI and ipsilateral metachronous PJI was 8 ± 14 months. Patients were followed for a minimum of 24 months for any complications. RESULTS: The risk of ipsilateral metachronous PJI in the other joint secondary to a joint implant in which PJI develops can increase up to 20% in the first 2 years after the procedure. There was no difference between the two groups in age, sex, initial joint replacement (knee or hip), and BMI. However, patients in the ipsilateral metachronous PJI group were shorter and had a lower weight (1.6 ± 0.1 m and 76 ± 16 kg). An analysis of the microbiological characteristics of bacteria at the time of the initial PJI showed no differences in the proportions of difficult-to-treat, high virulence, and polymicrobial infections between the two groups (20% [20 of 98] versus 80% [78 of 98]). Our findings showed that the ipsilateral metachronous PJI group had a shorter stem-to-stem distance, shorter empty native bone distance, and a higher risk of cement restrictor failure (p < 0.01) than the 78 patients who did not experience ipsilateral metachronous PJI during the study period. An analysis of the receiver operating characteristic curve showed a cutoff of 7 cm for the empty native bone distance (p < 0.01), with a sensitivity of 72% and a specificity of 75%. CONCLUSION: The risk of ipsilateral metachronous PJI in patients with multiple joint arthroplasties is associated with shorter stature and stem-to-stem distance. Appropriate position of the cement restrictor and native bone distance are important in reducing the risk of ipsilateral metachronous PJI in these patients. Future studies might evaluate the risk of ipsilateral metachronous PJI owing to bone adjacency. LEVEL OF EVIDENCE: Level III, therapeutic study.

Unexpected Positive Cultures in Patients Who Have a History of Septic Revision in the Same Joint.

BACKGROUND: The prevalence of unexpected positive cultures (UPC) in an aseptic revision surgery of the joint with a prior septic revision in the same joint remains unknown. The purpose of this study was to determine the prevalence of UPC in that specific group. As secondary outcomes, we explored risk factors for UPC. METHODS: This retrospective study includes patients who had an aseptic revision total hip/knee arthroplasty procedure with a prior septic revision in the same joint. Patients who had less than 3 microbiology samples, without joint aspiration or with aseptic revision surgery performed <3 weeks after a septic revision were excluded. The UPC was defined as a single positive culture in a revision that the surgeon had classified as aseptic according to the 2018 International Consensus Meeting. After excluding 47, a total of 92 patients were analyzed, who had a mean age of 70 years (range, 38 to 87). There were 66 (71.7%) hips and 26 (28.3%) knees. The mean time between revisions was 83 months (range, 31 to 212). RESULTS: We identified 11 (12%) UPC and in 3 cases there was a concordance of the bacteria compared to the previous septic surgery. There were no differences for UPC between hips/knees (P = .282), diabetes (P = .701), immunosuppression (P = .252), previous 1-stage or 2-stages (P = .316), causes for the aseptic revision (P = .429) and time after the septic revision (P = .773). CONCLUSION: The prevalence of UPC in this specific group was similar to those reported in the literature for aseptic revisions. More studies are needed to better interpret the results.

Periprosthetic joint infection in patients with multiple arthroplasties.

Despite numerous studies focusing on periprosthetic joint infections (PJIs), there are no robust data on the risk factors and timing of metachronous infections. Metachronous PJIs are PJIs that can arise in the same or other artificial joints after a period of time, in patients who have previously had PJI. Between January 2010 and December 2018, 661 patients with multiple joint prostheses in situ were treated for PJI at our institution. Of these, 73 patients (11%) developed a metachronous PJI (periprosthetic infection in patients who have previously had PJI in another joint, after a lag period) after a mean time interval of 49.5 months (SD 30.24; 7 to 82.9). To identify patient-related risk factors for a metachronous PJI, the following parameters were analyzed: sex; age; BMI; and pre-existing comorbidity. Metachronous infections were divided into three groups: Group 1, metachronous infections in ipsilateral joints; Group 2, metachronous infections of the contralateral lower limb; and Group 3, metachronous infections of the lower and upper limb. We identified a total of 73 metachronous PJIs: 32 PJIs in Group 1, 38 in Group 2, and one in Group 3. The rate of metachronous infection was 11% (73 out 661 cases) at a mean of four years following first infection. Diabetes mellitus incidence was found significantly more frequently in the metachronous infection group than in non-metachronous infection group. The rate of infection in Group 1 (21.1%) was significantly higher (p = 0.049) compared to Groups 2 (6.2%) and 3 (3%). The time interval of metachronous infection development was shorter in adjacent joint infections. Concordance between the bacterium of the first PJI and that of the metachronous PJI in Group 1 (21/34) was significantly higher than Group 2 (13/38; p = 0.001). The findings of this study suggest that metachronous PJI occurs in more than one in ten patients with an index PJI. Female patients, diabetic patients, and patients with a polymicrobial index PJI are at significantly higher risk for developing a metachronous PJI. Furthermore, metachronous PJIs are significantly more likely to occur in an adjacent joint (e.g. ipsilateral hip and knee) as opposed to a more remote site (i.e. contralateral or upper vs lower limb). Additionally, adjacent joint PJIs occur significantly earlier and are more likely to be caused by the same bacteria as the index PJI.

Acetabular Morphology Predicts the Risk of Dislocation Following Hemiarthroplasty for Femoral Neck Fractures in the Elderly.

BACKGROUND: Hip hemiarthroplasty dislocation is a devastating complication. Among other preoperative risk factors, acetabular morphology has been rarely studied. The purpose of the study was to evaluate the influence of preoperative native acetabular morphology on hemiarthroplasty dislocation. METHODS: We retrospectively reviewed 867 patients who underwent hip hemiarthroplasty for femoral neck fracture between January 1, 2014 and January 1, 2019. The 380 included patients were treated with an anterior-based muscle-sparing approach. The central-edge angle (CEA) and acetabular depth-to-width ratio (ADWR) of the fractured hip were measured preoperatively on the anteroposterior pelvic view. Receiver operating characteristic curves were performed to analyze the optimal cutoff for CEA and ADWR. Hemiarthroplasty dislocation occurred in 18 patients (4.7%), and the remaining 362 patients were used as the control group. RESULTS: No significant differences in terms of sex, age, dementia, neuromuscular disease, and body mass index were found between the 2 groups. The 18 patients who had a hip dislocation had significantly smaller mean CEA than the control group (P = .0001) (mean 36.1 ± 7.5° and 43.2 ± 5.6°, respectively) as well as ADWR (mean 34 ± 6 versus 37 ± 4, respectively) (P = .001). Using the receiver operating characteristic analysis, we report significant cutoffs of 38.5° for CEA (P = .0001) and 34.5 for the ADWR (P = .017). CONCLUSION: Higher rates of hemiarthroplasty dislocation were observed in patients who had a preoperative CEA of less than 38.5° and an ADWR of less than 34.5. Patients who have preoperative acetabular morphological risk factors for dislocation might be better candidates for a total hip arthroplasty.

Clinical outcomes and return to sport after single-stage revision anterior cruciate ligament reconstruction by bone-patellar tendon autograft combined with lateral extra-articular tenodesis.

PURPOSE: The anterior cruciate ligament reconstruction (ACLR) failure rate continues to increase. Involvement of a young population with a desire to return to sport, explains the increased need for ACLR (revACLR) revision. The aim of this study was to evaluate clinical outcome, complications, failure rate and return to sport of a single-stage revACLR using bone patellar tendon-bone (BTBT) combined with lateral extra-articular tenodesis (LET). MATERIAL AND METHODS: A retrospective analysis was performed on 36 patients who underwent revACLR. Knee stability was assessed by Lachman and Pivot shift test. Objective anterior laxity was determined by KT-2000 arthrometer. The IKDC subjective, Lysholm, ACL-RSI Scores, level of sport activity and Forgotten Joint Score-12 were recorded. RESULTS: Of 36 patients, we collected data from 17 who underwent single-stage revACLR with autologous BTBT combined with LET, performed using an extra-articular MacIntosh procedure as modified by Arnold-Coker. The side-to-side difference in Lachman test and Pivot shift test significantly improved postoperatively. The subjective IKDC, Lysholm and ACL-RSI significantly improved from 71.4 ± 9.03 to 92 ± 6.9, from 58.3 ± 19.3 to 66.8 ± 27.7 and from 50.4 ± 12.2 to 68.6 ± 24.5, respectively during the post-operative follow-up. Ten patients (58.8%) returned to their desired level of sport. One patient was considered a failure because of the postoperative laxity. CONCLUSION: Single-stage revACLR with BPTB combined with LET is a safe procedure that shows good objective and subjective outcomes, and a high rate of return to the same level of sport. Reducing rotational instability and strain on intra-articular reconstructed structures results in a low rate of complications and failure.

Successful eradication rate following one-stage septic knee and hip exchange in selected pre-operative culture-negative periprosthetic joint infections.

PURPOSE: The main requirement for performing the one-stage septic exchange is the pre-operative identification of the pathogen and its susceptibility. The purpose of this study is to evaluate the success rate with special focus on reinfection in a cohort of patients who underwent one-stage septic knee or hip revision for pre-operative culture-negative PJI. METHODS: We retrospectively analyzed 640 patients treated by one-stage revision for chronic knee or hip PJI between January 1, 2016, and December 31, 2018. Only cases with pre-operative culture-negative PJI, with culture-negative synovial aspirations and one negative open biopsy, were analyzed. We evaluated the septic and aseptic complication and the rate of complication-free survival defined as the time from the date of first operation and the date of complication events. RESULTS: A total of 22 patients fulfilled the inclusion and were enrolled. The mean age of the group was 73.2 ± 9.8 years, with a median ASA score of 3 (range 3-4). After mean follow-up of 3.6 ± 2.6 years, 86.4% (19 out of 22) of patients reported no complications. Two patients (9.1%) after one-stage hip required revision arthroplasty due to septic failure, while one patient (4.5%) with one-stage knee had revision for femoral component aseptic loosening. CONCLUSION: Our analysis suggests that the absence of pre-operative pathogen detection may not be contraindication to the one-stage revision in selected patients. The one-stage exchange might be considered in patients with pre-operative negative cultures in presence of ASA > 3 and multiple comorbidities that are not able to tolerate multiple surgeries.

Outcome of surgically treated acetabular fractures: risk factors for postoperative complications and for early conversion to total hip arthroplasty.

INTRODUCTION: The gold standard of Acetabular fractures treatment is open reduction and internal fixation (ORIF). Our purpose is to assess the short- to medium-term outcomes and complications of surgically treated acetabular fractures. We analysed factors influencing clinical outcomes, incidence of complications and predictors of conversion in total hip arthroplasty (THA). MATERIALS AND METHODS: We retrospectively analysed 102 patients with acetabular fracture surgically treated between December 2017 and September 2020. We evaluated the quality of reduction with x-ray measuring residual displacement, classified into 3 groups (Matta Radiological Score). At the final follow-up, radiographs were graded according to Matta's Radiological Outcome Grading, and the clinical outcomes were graded using Oxford Hip Score (OHS). RESULTS: 62 patients were enrolled. OHS was influenced by quality of reduction (p = 0.031), injury severity score (ISS) (p = 0.003) and BMI > 30 (p < 0.0001). The late sequelae were heterotopic ossification (HO) in 13 patients, osteoarthritis (OA) in 22 and avascular necrosis (AVN) in 4. HO was significantly affected by posterior approach and ISS > 15. The analysis showed a correlation between AVN and posterior hip dislocation. OA had a correlation with postoperative quality of reduction (p = 0.014). Eight patients required THA with a significant correlation between THA and posterior dislocation, isolated posterior wall fracture and ISS > 15. CONCLUSION: A high rate of patients with acetabular fractures still develop complications and require THA. Identification of predictors for poor outcome may help to inform surgical decision-making regarding options of plate osteosynthesis or 'Fix and Replace', to avoid poor outcomes and early revision surgery.

What is the concordance rate of preoperative synovial fluid aspiration and intraoperative biopsy in detecting periprosthetic joint infection of the shoulder?

BACKGROUND: The accuracy of preoperative synovial fluid culture for microbe detection in shoulder periprosthetic joint infection (PJI) is poorly described. To evaluate the utility of preoperative culture data for early pathogen identification for shoulder PJI, we determined the concordance between preoperative synovial fluid culture results and intraoperative tissue culture results. METHODS: Fifty patients who met the 2014 Musculoskeletal Infection Society criteria for shoulder PJI between January 2016 and December 2019 were retrospectively reviewed for clinical and demographic data. This cohort of patients was divided into 2 groups based on the concordance between preoperative and intraoperative culture results. The pathogens identified on preoperative and intraoperative cultures were classified as high-virulence or low-virulence. Student's t tests and Mann-Whitney U tests were used as appropriate for continuous variables, and χ2 and Fisher's exact tests were used as appropriate for categorical variables. RESULTS: Concordance between preoperative aspiration and intraoperative tissue culture was identified in 28 of 50 patients (56%). Preoperative cultures positive for Gram-positive species were more likely to be concordant than discordant (P = .015). Preoperative cultures positive for Cutibacterium acnes were more likely to be concordant with intraoperative cultures (P = .022). There were more patients with polymicrobial infection in the discordant group compared with the concordant group (P < .001). No statistically significant correlation between the preoperative serum C-reactive protein level and the intraoperative category of bacteria was reported. Staphylococcus aureus and coagulase-negative Staphylococci were associated with high specificity and negative predictive value. Preoperative cultures positive for C. acnes demonstrated sensitivity, specificity, positive predictive value, and negative predictive value lower than 0.8. Gram-negative pathogens demonstrated the highest sensitivity (1) and specificity (1), whereas polymicrobial infections exhibited the lowest sensitivity and positive predictive value. CONCLUSION: Preoperative synovial fluid aspiration for shoulder PJI poorly predicts intraoperative culture results, with a discordance of 44%. More favorable concordance was observed for monomicrobial preoperative cultures, particularly for Gram-negative organisms and methicillin-sensitive S. aureus. The overall high rate of discordance between preoperative and intraoperative culture may prompt surgeons to base medical and surgical management on patient history and other factors and avoid relying solely on preoperative synovial fluid culture data.

Time to Positivity of Cultures Obtained for Periprosthetic Joint Infection.

BACKGROUND: Despite its well-established limitations, culture remains the gold standard for microbial identification in periprosthetic joint infection (PJI). However, there are no benchmarks for the time to positivity (TTP) on culture for specific microorganisms. This study aimed to determine the TTP for pathogens commonly encountered in PJI. METHODS: This retrospective, multicenter study reviewed prospectively maintained institutional PJI databases to identify patients who underwent hip or knee revision arthroplasty from 2017 to 2021 at 2 tertiary centers in the United States and Germany. Only patients who met the 2018 International Consensus Meeting (ICM) criteria for PJI and had a positive intraoperative culture were included. TTP on culture media was recorded for each sample taken intraoperatively. The median TTP was compared among different microbial species and different specimen types. Data are presented either as the mean and the standard deviation or as the median and the interquartile range (IQR). RESULTS: A total of 536 ICM-positive patients with positive cultures were included. The mean number of positive cultures per patient was 3.9 ± 2.6. The median TTP, in days, for all positive cultures was 3.3 (IQR, 1.9 to 5.4). Overall, gram-negative organisms (TTP, 1.99 [1.1 to 4.1]; n = 225) grew significantly faster on culture compared with gram-positive organisms (TTP, 3.33 [1.9 to 5.8]; n = 1,774). Methicillin-resistant Staphylococcus aureus (TTP, 1.42 [1.0 to 2.8]; n = 85) had the fastest TTP, followed by gram-negative rods (TTP, 1.92 [1.0 to 3.9]; n = 163), methicillin-sensitive Staphylococcus aureus (TTP, 1.95 [1.1 to 3.3] n = 393), Streptococcus species (TTP, 2.92 [1.2 to 4.3]; n = 230), Staphylococcus epidermidis (TTP, 4.20 [2.4 to 5.5]; n = 555), Candida species (TTP, 5.30 [3.1 to 10]; n = 63), and Cutibacterium acnes (TTP, 6.97 [5.9 to 8.2]; n = 197). When evaluating the median TTP according to specimen type, synovial fluid (TTP, 1.97 [1.1 to 3.1]; n = 112) exhibited the shortest TTP, followed by soft tissue (TTP, 3.17 [1.4 to 5.3]; n = 1,199) and bone (TTP, 4.16 [2.3 to 5.9]; n = 782). CONCLUSIONS: To our knowledge, this is the first study to examine the TTP of common microorganisms that are known to cause PJI. Increased awareness of these data may help to guide the selection of appropriate antimicrobial therapy and to predict treatment outcomes in the future. Nonetheless, additional studies with larger cohorts are needed to validate these benchmarks. LEVEL OF EVIDENCE: Diagnostic Level IV . See Instructions for Authors for a complete description of levels of evidence.

The use of posteromedial portal for arthroscopic treatment of synovial chondromatosis of the knee: a case report.

BACKGROUND: The synovial chondromatosis is an uncommon proliferative metaplastic process of the synovial cells that can develop in any synovial joint. An isolated primary chondromatosis of the posterior compartment of the knee is uncommon and few cases are reported in literature. Our purpose is to describe a rare case of primary chondromatosis of the knee posterior compartment and report the arthroscopic loose bodies excision through a difficult posteromedial portal, avoiding the use of the accessory posterior portal, most commonly reported for approaching this disease. CASE PRESENTATION: We report a rare case of a 35-year-old Caucasian male patient with diagnosis of chondromatosis of the posterior knee compartment. The radiographs showed multiple loose bodies of the posterior compartment. The MRI revealed minimal synovial hypertrophy areas, multiple osteophytes in the intercondylar notch, and loose bodies in the posteromedial compartment. The CT allowed us to assess the bony structures, the morphology of the intercondylar notch, and the presence osteophytes of the medial and lateral femoral condyles. The CT images were crucial to plan how to reach the posterior compartments of the knee through a trans-notch passage. The patient underwent arthroscopic surgery using anteromedial, anterolateral, and posteromedial portals. The tunneling through the intercondylar osteophytes was performed to allow the arthroscope to pass trans-notch. To avoid additional accessory posterior portals, we used a 70° arthroscope to better explore the posterior knee compartment. The cartilage-like bodies were removed and synovectomy of the inflamed areas was performed. The clinical and radiological follow-up was 12 months and the patient showed excellent clinical outcomes, returning to his activities of daily living and sport activity. CONCLUSION: Our case report highlights the importance of the arthroscopic approach to treat synovial chondromatosis, despite the involvement of the posterior compartment of the knee. An optimal preoperative imaging allows to plan for the proper surgical procedure even in patients with severe osteoarthritis. Moreover, the adoption of an intercondylar notch tunneling and a 70° arthroscope can help surgeons to better explore the posterior knee compartment, avoiding an accessory posterior trans-septal portal. Therefore, a synovectomy of the inflamed foci may be useful to prevent recurrence.

Varus morphology and its surgical implication in osteoarthritic knee and total knee arthroplasty.

BACKGROUND: Knee varus alignment represents a notorious cause of knee osteoarthritis. It can be caused by tibial deformity, combined tibial-femoral deformity and/or ligament imbalance. Understanding malalignment is crucial in total knee arthroplasty to restore frontal plane neutral mechanical axis. The aim of this study was to determine which factor contributes the most to varus osteoarthritic knee and its related surgical implications in performing a total knee arthroplasty. METHODS: We retrospectively evaluated 140 patients operated for total knee arthroplasty due to a varus knee. Full-leg hip to ankle preoperative X-rays were taken. Radiological parameters recorded were: mechanical axis deviation, hip-knee-ankle, anatomical-mechanical angle, medial neck shaft angle, mechanical lateral distal femoral angle (mLDFA), medial proximal tibial angle (MPTA), joint line convergence angle (JLCA), lateral proximal femoral angle, lateral distal tibial angle (LDTA), femoral bowing, and length of tibia and femur. We also determined ideals tibial and femoral cuts in mm according to mechanical alignment technique. A R2 was calculated based on the linear regression between the predicted values and the observed data. RESULTS: The greatest contributor to arthritic varus (R = 0.444) was MPTA. Minor contributors were mLDFA (R = 0.076), JLCA (R = 0.1554), LDTA (R = 0.065), and femoral bowing (R = 0.049). We recorded an average of 7.6 mm in lateral tibial cut thickness to restore neutral alignment. CONCLUSIONS: The radiological major contributor to osteoarthritic varus knee alignment is related to proximal tibia deformity. As a surgical consequence, during performing total knee arthroplasty, the majority of the correction should therefore be made on tibial cut.

Positive Cultures Can Be Safely Ignored in Revision Arthroplasty Patients That Do Not Meet the 2018 International Consensus Meeting Criteria.

BACKGROUND: During aseptic revision total joint arthroplasty (TJA), one or more cultures may occasionally isolate an organism. The hypothesis of this study was that in a portion of patients undergoing revision arthroplasty for aseptic failure, culture may isolate an organism(s) that can be left untreated. METHODS: All patients undergoing revision TJA from 2000 to 2017 at two institutions were retrospectively reviewed. Patients were categorized as aseptic if they were appropriately investigated preoperatively and did not meet the 2018 International Consensus Meeting criteria. In the aseptic revision cohort, patients with a single positive culture or multiple cultures positive for different organisms ("organism-positive") and patients who had negative intraoperative cultures ("organism-negative") were compared based on demographics, comorbidities, operative details, subsequent reoperations, and periprosthetic joint infection (PJI). RESULTS: In total, 3,234 International Consensus Meeting-negative aseptic revision TJAs were included, of which 215 patients (6.6%) were organism-positive, 196 (91.2%) had a single positive culture, and 19 (8.8%) were positive for 2 or more distinct organisms (ie, polymicrobial). The most prevalent organisms were coagulase-negative Staphylococci (37.5%), Staphylococcus epidermidis (9.6%), and Cutibacterium acnes (8.0%). Demographics and operative details were comparable between the groups. Using multiple regressions there was no association between culture positivity and the rate of reoperation or PJI. CONCLUSION: Isolation of organisms by culture in patients undergoing revision for aseptic failure was not uncommon. As long as these patients were appropriately investigated preoperatively and PJI was excluded, these findings suggest that culture results may be ignored without subjecting patients to additional antimicrobial treatment.

Periprosthetic femoral fractures in Total Hip Arthroplasty (THA): a comparison between osteosynthesis and revision in a retrospective cohort study.

BACKGROUND: Periprosthetic femoral fractures are challenging complications of hip arthroplasty. They are supposed to be a rare complication, but their incidence is rapidly increasing. Surgical treatment aims to achieve early mobilization and avoid the complications of prolonged bed rest. Aim of this study is to evaluate the clinical outcomes of surgical treatment comparing two surgical approaches: revision arthroplasty (RA) versus open reduction and internal fixation (ORIF). METHODS: Authors retrospectively reviewed a series of 117 patients with total hip arthroplasty treated for periprosthetic femur fractures in the period between January 2013 and March 2018 at a single tertiary referral center. Of these, 70 patients satisfied strict inclusion criteria. Patients were classified according to the Unified Classification System (UCS) and distributed in two groups according to surgical treatment. Clinical outcomes were assessed using the Oxford Hip recorded preoperatively and post operatively, Barthel Score, CIRS score (Cumulative illness rating scale), type of fracture and post-operative complications with a minimum follow up of 1 year. RESULTS: Nominal univariate statistical analysis revealed significant differences between the post and pre-operative Oxford Hip Score (Δ Oxford) and the surgical treatment (p = 0.008) and CIRS score (p = 0.048). Moreover, we observed a significant relationship between type of treatment and type of fracture (p = 0.0001). Multivariate analyses revealed that CIRS score was independently associated with Oxford Score improvement after surgery (p = 0.024). CONCLUSIONS: Data from this case series confirmed that surgical treatment was correlated to type of fracture, according to UCS classification. Patients treated by RA had a better functional outcome than patients treated with ORIF, but these results are strongly influenced from the patients' age, Barthel index and CIRS score. Also, authors found a correlation between functional outcome and comorbidities evaluated by CIRS score. Based on these data we suggest a multimodal approach to these patients, like those used for proximal femoral fractures.