Periprosthetic knee infection reconstruction with a hinged prosthesis: Implant survival and risk factors for treatment failure

BackgroundSevere bone and soft tissue defects are common after failed two-stage exchange arthroplasty for periprosthetic joint infection (PJI). There is a paucity of evidence on the outcomes of using a hinged prosthesis for knee PJI reconstruction during second-stage re-implantation, especially regarding implant survivorship, reinfection risk factors, and functionality after successful reconstruction.MethodsA total of 58 knee PJI patients with Anderson Orthopaedic Research Institute (AORI) type II/III defect and soft tissue insufficiency underwent reconstruction with hinged prosthesis. Enrolled patients adhered to a two-stage exchange arthroplasty protocol and were evaluated for a mean follow up of 65.1 months. Kaplan–Meier analysis was conducted for implant survivorship and infection-free survival. Multivariate analysis was used to determine independent risk factors for recurrent infections. Knee Society Score (KSS) was used to evaluate functional outcomes.ResultsThe survivorship of hinged prosthesis was 86.2% at 2 years and 70.2% at 5 years. Infection-free analysis revealed an estimation of 68.9% at 2 years and 60.6% at 5 years. Of the 58 patients, 13 (22.4%) developed recurrent PJI, three (5.2%) aseptic loosening, and one (1.7%) periprosthetic fracture. Multivariate analysis revealed that obesity (hazard ratio (HR), 3.11), high-virulent pathogen (HR, 3.44), and polymicrobial infection (HR, 3.59) were independent risk factors for reinfection. Patients showed a mean improvement of 32.8 ± 7.7 in Knee Society Clinical Score (KSCS) and 30.8 ± 11.0 in Knee Society Function Score (KSFS) after successful reconstruction (P < 0.001).ConclusionsUsing hinged knee prosthesis for PJI reconstruction provided an overall implant survival of 70.2% and an infection-free survival of 60.6% at mid-term follow up. Obesity, virulent pathogens, and polymicrobial infections were independent risk factors for infection recurrence.     

Revision total knee arthroplasty outcomes in solid organ transplant Patients,a matched cohort study of aseptic and infected revisions

BackgroundPrevious studies have demonstrated that solid organ transplant (SOT) patients undergoing primary total knee arthroplasty (TKA) are at an increased risk of postoperative complications. The purpose of this study is to utilize a large, national database to investigate revision TKA (rTKA) outcomes in SOT patients.MethodsThis was a retrospective review utilizing the Nationwide Readmissions Database (NRD) and ICD-9 codes to identify patients who underwent rTKA from 2010-2014 with a history of at least one SOT. Propensity-score-matching (PSM) was used to compare rTKA outcomes in SOT patients compared to matched patients without SOT.ResultsA total of 303,867 rTKAs, with 464 of those being performed in SOT patients, were included in the study. Of these, 71,903 and 182 were performed for PJI in non-SOT and SOT patients, respectively. rTKA was performed most frequently in kidney transplant patients (53.0%) followed by liver transplant patients (34.3%). For non-PJI patients, SOT patients had a higher 90-day readmission rate than matched non-SOT rTKA patients (23.2% vs 12.6%, p = 0.006). However, there were no differences in 90-day readmission rates for specific rTKA complications, subsequent revision rTKA, or mortality. Among patients undergoing rTKA for PJI, there was no difference in overall 90-day readmission rate, readmission for specific rTKA complications, subsequent revision rTKA, or mortality.ConclusionsWhile the increased medical comorbidities associated with SOT place patients at increased risk for complications following rTKA, it appears that SOT alone does not do so when patients are matched based on overall medical comorbidity.     

Satisfaction with playing pre-injury sports 1 year after anterior cruciate ligament reconstruction using a hamstring autograft

BackgroundFew studies have examined patient satisfaction with playing pre-injury sports after anterior cruciate ligament (ACL) reconstruction. The purpose of this study was to investigate patient satisfaction with playing pre-injury sport and identify factors associated with satisfaction.MethodsA total of 97 patients underwent unilateral ACL reconstruction using a hamstring autograft and returned to pre-injury sports 1 year after surgery. Patient satisfaction with playing pre-injury sport was assessed by a visual analog scale (VAS) and an ordinal four-grade scale. Problems related to the operated knee were also assessed. Knee muscle strength, single leg hop distance, knee laxity, subjective knee pain, and fear of movement/reinjury using Tampa Scale for Kinesiophobia-11 (TSK-11) were measured. Multivariate linear regression analysis was performed to determine the factors associated with patient satisfaction with playing pre-injury sport 1 year after surgery.ResultsThe average VAS score for patient satisfaction with playing pre-injury sports 1 year after surgery was 77.8 ± 20.2. Of the 97 patients, 87 patients (89.7%) answered “satisfied” or “mostly satisfied”, whereas 51 patients (52.6%) had one or more problems. Multivariate linear regression analysis identified that the TSK-11 score was associated with patient satisfaction with playing a pre-injury sport 1 year after surgery.ConclusionMost of the patients who returned to pre-injury sports were satisfied with their outcomes. In contrast, approximately half of the patients had one or more problems after returning to play pre-injury sports. In particular, fear of movement/reinjury was significantly associated with patient satisfaction with playing pre-injury sport 1 year after surgery.     

The midterm results of a cohort study of patellofemoral arthroplasty from a non-designer centre using an asymmetric trochlear prosthesis

PurposePatellofemoral arthroplasty (PFA) prosthesis with asymmetric trochlear component was introduced as an improvement from existing designs for surgical treatment of symptomatic isolated patellofemoral arthritis. The purpose of this study was to evaluate midterm results in patients who underwent PFA procedure using such prosthesis.MethodsOur study involved a continuous retrospective cohort of patients who underwent PFA using Journey PFA prosthesis with an asymmetric trochlear component, performed between June 2007 and July 2016 at a non-designer centre. The Patient Reported Outcome Measures and patient satisfaction questionnaires were collected for final evaluation.ResultsA total of 103 PFA performed on 79 patients were evaluated. Median age at the time of surgery was 58 years (range 42 to 78 years); the mean follow-up period was 6 years (range 2 to 11 years). Four knees were revised to Total Knee Arthroplasty for reasons not related to the implant. The cumulative survival estimated by the Kaplan–Meier method was 94.3% (95% confidence interval: 88.4%–100%). There were statistically significant improvements in functional outcome scores.ConclusionThis series of patients who underwent PFA with the asymmetric trochlear component has shown promising mid-term results with no implant-related complications.     

Unicompartmental knee arthroplasty is associated with lower proportions of surgical site infection compared with total knee arthroplasty: A retrospective nationwide database study

BackgroundThis study aimed to clarify the association between types of knee arthroplasty (KA) (total knee arthroplasty (TKA) or unicompatmental knee arthroplasty (UKA)) and surgical site infection (SSI) with adjustment for various factors, using a Japanese national database.MethodsData on 181,608 patients who underwent unilateral primary KA for osteoarthritis from 2010 to 2017 were obtained from the Japanese Diagnosis Procedure Combination database. SSI was identified based on International Classification of Diseases 10th Revision codes. Deep SSI (i.e. periprosthetic joint infection (PJI)) was identified as SSI treated with surgical procedures. Multivariable logistic regression analyses for SSI and PJI were performed, in which dependent variables included types of KA, patient backgrounds (sex, age, body mass index (BMI), smoking status, comorbidities), and seasonality.ResultsEight percent of analyzed patients underwent UKA, while 92% underwent TKA. The proportions of SSI and PJI after UKA were 0.9% and 0.3%, respectively, both of which were lower than those after TKA (1.9% and 0.6%) (P < 0.001). Multivariable analyses showed lower proportions of SSI for UKA (adjusted odds ratio, 0.47; 95% confidence interval, 0.37–0.60; P < 0.001) and PJI (adjusted odds ratio, 0.47; 95% confidence interval, 0.34–0.65; P < 0.001) than TKA. Other factors associated with both SSI and PJI included male sex, BMI >30 kg/m², renal dysfunction and summer season.ConclusionUKA was associated with lower proportions of SSI and PJI than TKA. Surgeons should carefully consider the indication of UKA before performing TKA, especially in patients with knee unicompartmental osteoarthritis who are at a high risk for SSI or PJI.     

Avoidance of intramedullary violation in computer-assisted total knee arthroplasty lowers the incidence of periprosthetic joint infection compared with conventional total knee arthroplasty: A propensity score matching analysis of 5342 cases

BackgroundConventional total knee arthroplasty (CONV-TKA) inevitably perturbs femoral medullary canal, disturbs medullary micro-architecture and increases blood loss and inflammatory responses. We hypothesized that avoidance of intramedullary violation may lower the incidence of periprosthetic joint infection (PJI). The aim of this study was to verify whether computer-assisted total knee arthroplasty (CAS-TKA) lowers the incidence of PJI as compared with CONV-TKA.MethodsA propensity score matching study of 5342 patients who underwent CAS-TKA (n = 1085) or CONV-TKA (n = 4257) for primary osteoarthritis of the knee from 2007 to 2015 in our institute was performed. Patients who underwent CAS-TKA were matched to those who received CONV-TKA at a 1:2 ratio according to demographics and comorbidities. PJI was defined according to the Musculoskeletal Infection Society diagnostic criteria from the 2013 International Consensus Meeting.ResultsAfter controlling potential risk factors, the use of CAS-TKA resulted in a lower incidence of PJI as compared with CONV-TKA [adjusted hazard ratio (HR), 0.42; 95% confidence interval (CI), 0.18–0.99]. The same trend in PJI reduction was observed with the usage of CAS-TKA under sensitivity testing [HR, 0.33; 95% CI, 0.12–0.95]. The cumulative incidence of PJI was lower in the CAS-TKA group than the CONV-TKA group (log-rank test, p = 0.013).ConclusionAvoidance of intramedullary violation during TKA may play a pivotal role in lowering the incidence of PJI. The use of CAS-TKA can reduce the incidence of PJI, with a better survival rate in terms of being free of PJI, as compared with CONV-TKA.Level of evidence III.     

Accelerated rehabilitation program following medial patellofemoral ligament reconstruction does not increase risk of recurrent instability

BackgroundRehabilitation protocols following medial patellofemoral ligament (MPFL) reconstruction were historically restrictive, with patients often immobilized and/or given weightbearing restrictions. However, more recently published protocols have been more aggressive. We compared patient-reported outcomes and recurrent dislocation risk between patients treated with a restrictive rehabilitation program (early post-operative bracing and weightbearing restrictions) and an accelerated rehabilitation protocol (no post-operative bracing or weightbearing restrictions) following MPFL reconstruction.MethodsPatients who underwent isolated MPFL reconstruction at an academic center between 2008 and 2016 were identified. Patient demographics, anatomical measurements, surgical details, and outcomes were collected. During this period, the rehabilitation protocol at the center transitioned from a restrictive to an accelerated rehabilitation protocol. Failure risk and patient-reported outcomes were compared based on rehabilitation protocol.ResultsOf the163 isolated MPFL reconstructions performed during the study period, 123 (75%) were available for minimum one-year follow up at a mean of 4.0 years post-operative. Overall, 53 knees (43%) underwent the accelerated rehabilitation protocol and the remaining 70 knees (57%) underwent the restrictive protocol. There were 3 recurrent dislocations during the study period (2.4%), all of which occurred in the restrictive rehabilitation group. Multiple linear regression demonstrated that being in the accelerated rehabilitation group was not associated with poorer Knee injury and Osteoarthritis Outcome Score (KOOS) subscales controlling for age, sex, body mass index, Caton-Deschamps Index, tibial tubercle-trochlear groove distance, sulcus angle, MPFL graft choice, and length of follow-up.ConclusionAn accelerated rehabilitation protocol without immobilization or weightbearing restrictions does not increase risk of recurrent patellar dislocation or poorer patient-reported outcome following isolated MPFL reconstruction.     

Conforming patellar button design improves outcome of total knee arthroplasty

BackgroundPatellar resurfacing is commonly performed during total knee arthroplasty (TKA), and the patellar button design can vary within a TKA implant. Implant design is known to affect patella kinematics, contact mechanics, and ultimately the outcome of TKA. The aim of this study was to compare the patient-reported outcomes of TKA with either a conforming (CP) or medialized dome (MD) patellar component.MethodsThe study was a prospective cohort study of 100 TKAs performed between December 2015 and August 2017. We compared a consecutive series of 50 TKA subjects with a CP, with the previous 50 TKA subjects with an MD patella. The primary outcome measure was difference in Knee Injury and Osteoarthritis Score (KOOS) at 12 months. Other patient-reported outcome measures included EQ5D as a general health measure, and patient satisfaction.ResultsThere was no significant difference in baseline characteristics, KOOS, or EQ5D between the two groups. At 12 months, the CP Group had a higher mean KOOS function score (87 vs. 80, P = 0.04), and greater patient satisfaction (98% vs. 82% satisfied, P = 0.009) compared with the MD group. The CP Group had significantly lower frequency of pain with level walking, less difficulty with stairs, and lower mean EQ5D mobility at 12 months compared with the MD group.ConclusionsTKA performed using a conforming patella has superior results over a medialized dome patellar component for KOOS function, patient satisfaction, walking pain, stair performance, and mobility at 12 months postoperatively. The differences observed with the change in patellar design may be unique to this prosthesis.     

Selective bundle reconstruction in partial ACL tears leads to excellent long-term functional outcomes and a low percentage of failures

BackgroundThe optimal treatment of partial anterior cruciate ligament (ACL) tears continues to be debatable. Short-term results of selective bundle reconstruction have already been widely shown. The purpose of this study was to assess functional outcomes, subjective satisfaction and the failure rate of selective bundle reconstructions for partial ACL tears over a five to nine year follow-up period.MethodsPatients who underwent ACL selective bundle reconstruction between October 2008 and October 2012 were studied. Functional assessment was performed with the objective International Knee Documentation Committee (IKDC) ligament evaluation form, the Lysholm knee scale and the Tegner activity level scale. Cumulative failure and level of satisfaction have also been investigated.ResultsSeventy-six patients were included. The average follow-up period was 85 months (range 65–110). Thirty-four had AMB tear and 42 had PLB tears. An overall statistically significant improvement (p < 0.001) was obtained in terms of the subjective IKDC and the Lysholm questionnaire between preoperative and last follow-up. The same or no more than one level lower Tegner score was restored in 97.3% of the cases. Cumulative failure was observed in two patients (2.6%). Dissatisfied patient percentage was 15% (4/76).ConclusionsSelective bundle reconstruction in partial ACL tears leads to excellent long-term functional outcomes, a low percentage of failures and a high degree of subjective satisfaction in patients.Level of evidenceTherapeutic case series; level 4.     

Clinical outcomes and patient satisfaction following revision of failed unicompartmental knee arthroplasty to total knee arthroplasty are as good as a primary total knee arthroplasty

BackgroundWith unicompartmental knee arthroplasty (UKA) being increasingly performed for medial compartment osteoarthritis (OA) of the knee, revision total knee arthroplasty (TKA) for failed UKA is expected to increase. Our primary aim is to evaluate patients in our tertiary institution who underwent revision of failed UKA to TKA to compare their pre-operative clinical scores (patient-reported outcome measures, PROMs) to those of primary TKA.MethodsRetrospective review of our institutional arthroplasty registry between 2001 and 2014 was performed. We identified 70 patients who underwent revision of UKA to TKA. The revision UKA to TKA patients was matched with 140 patients who underwent primary TKA for OA in terms of preoperative demographics, gender, age at time of surgery, body mass index (BMI), primary surgeon, and PROMs. Intra-operative data and postoperative complications or re-revision surgeries performed were reviewed.ResultsIn the revision UKA to TKA group, more stems, augments or constrained implants were used compared to primary TKA. A greater proportion of patients with metal-backed UKA revision to TKA required stems, augments or constrained implants as compared to all-polyethylene UKA revision to TKA, but not a significant proportion (P = 0.250). At two years postoperatively, there were no significant differences observed between the groups in terms of patient satisfaction and PROMs.ConclusionsThis study showed similar outcomes following revision of failed UKA to TKA and primary TKA. There were significant improvements in PROMs for revision UKA to TKA, which is comparable to that of primary TKA.     

Inferior outcomes of total knee replacement in early radiological stages of osteoarthritis

BackgroundTotal knee replacement (TKR) for osteoarthritis (OA) is a common and successful operation; the severity of radiographic changes plays a key role as to when it should be performed. This study investigates whether an early radiological grade of OA has an adverse effect on the outcome of TKR in patients with arthroscopically confirmed OA.MethodsBetween January 2006 and January 2011 data was collected prospectively on all patients undergoing a primary TKR for OA. We included all patients with a Kellgren–Lawrence score of two or less on their pre-operative radiograph who had had an arthroscopy to confirm significant OA. Our primary outcomes were the Oxford Knee Score (OKS) and a satisfaction rating.ResultsOver the study period 1708 primary TKRs were performed in 1381 patients. We identified 44 TKRs in 43 patients with a Kellgren–Lawrence score of two or less on their pre-operative radiograph. In this group the mean age was 63 years, 66% were female and the mean BMI was 31.7 kg/m². At a mean follow-up of 37 months the mean OKS was only 30 points compared to 36 in all TKRs performed over the same period (p = 0.0004). Only 68% were either satisfied or very satisfied. Eight knees (18%) underwent further surgery, three (6.8%) of which were revision procedures, compared to a revision rate of 1.6% in all patients.ConclusionThe outcomes of TKR in patients with early radiological changes of OA are inferior to those with significant radiological changes and should be performed with caution.Level of evidenceLevel IV case-series.     

The oxford knee score minimal clinically important difference for revision total knee arthroplasty

BackgroundMinimal clinically important difference (MCID) is crucial for interpreting meaningful improvements in patient-reported outcome measures (PROMs). No previous study has evaluated the MCID for the Oxford Knee Score (OKS) in revision total knee arthroplasty (TKA). This study aimed to propose the OKS MCID for revision TKA.MethodsProspectively collected data from 191 patients who underwent revision TKA at a single institution was analysed. Clinical assessment was performed preoperatively and at 2 years using OKS and Short-Form 36 Physical Component Score (SF-36 PCS). MCID was evaluated with a three-pronged methodology, using (1) anchor-based method with linear regression, (2) anchor-based method with receiver operating characteristic (ROC) and area under curve (AUC), (3) distribution-based method with standard deviation (SD). The anchors used were improvement in SF-36 PCS ≥ 12, patient satisfaction, and implant survivorship following revision TKA.ResultsThe MCID determined by anchor-based linear regression method using improvements in SF-36 PCS was 4.9 points. The MCID determined by anchor-based ROC was 10.5 points for satisfaction (AUC = 74.8%) and 13.5 points for implant survivorship (AUC = 73.7%). The MCID determined by distribution-based method of 0.5 SD was 4.7.ConclusionThe proposed MCID for OKS following revision TKA is 4.9 points. Patients who achieve an improvement in OKS of at least 10.5–13.5 points by 2 years are likely to be satisfied with their surgery and not require a subsequent re-revision TKA. Patients undergoing revision TKA should aim for an improvement in OKS of at least 10.5–13.5 points as a target score.     

No difference in long-term outcomes between men and women undergoing medial fixed-bearing cemented unicompartmental knee arthroplasty: A retrospective cohort study with minimum 10-year follow up

BackgroundSome studies have suggested that women have poorer short-term outcomes after unicompartmental knee arthroplasty (UKA) due to a higher incidence of implant overhang. This study aimed to compare patient-reported outcome measures (PROMs) between men and women after UKA at a minimum follow-up of 10 years.MethodsPatients who underwent medial fixed-bearing UKA by two arthroplasty surgeons were identified from an institutional joint registry. Men and women were matched for age, body mass index, Charlson Comorbidity Index, American Society of Anesthesiologists class, range-of-motion and baseline PROMs using propensity scores. PROMs were compared at 2 and 10 years. Patients also completed a satisfaction questionnaire during these visits. Radiographic outliers were defined as > 2 mm of overhang.ResultsA total of 128 patients were included. There was no difference in complications, length of stay or readmissions. Women had poorer Knee Society functional scores, Short-Form 36 physical and mental component scores (SF-36 MCS) at 2 years. No difference in PROMs was found at 10 years, except for poorer SF-36 MCS in women (P = 0.041). At 10 years, 96% of women and 92% of men were satisfied (P = 0.243). Fifteen-year survivorship free from any revision was 96% in each group. There were more medial-tibial outliers in women (9%) compared with men (5%) (P = 0.018). However, no association between outliers and outcomes or survivorship was found on multivariate analyses.ConclusionThere was no difference in clinical outcomes between men and women undergoing UKA at a minimum follow-up of 10 years. While women had a higher incidence of medial tibial overhang, this was not associated with long-term outcomes or survivorship.     

Midterm clinical and radiographic outcomes of 115 consecutive patient-specific unicompartmental knee arthroplasties

BackgroundPoor implant positioning has been identified as a factor in early failure of unicompartmental knee arthroplasty. The aim of this study was to report the accuracy of component positioning, and midterm clinical, functional and radiological outcomes following patient-specific instrumented (PSI) unicompartmental knee arthroplasty (UKA).MethodsA total of 115 PSI-UKA were included. The primary outcomes were UKA survival, complication, and failure rates. Tibial implant positioning was determined using plain radiographs. Functional assessment included Oxford Knee Score (OKS), Forgotten Joint Score (FJS), patient satisfaction, and range of motion (ROM).ResultsThe survival rate of PSI-UKA was 92% after a mean follow-up of 55 months. The complication and failure rate was 13% and eight percent, respectively. The tibial component was accurately implanted in the desired frontal and sagittal alignment with a minor deviation of 0.3° (SD 1.9°) and 0.4° (SD 2.6°) to the preoperative planning. OKS increased from 24 (SD eight) points to 44 (SD six). FJS was 87 (SD 23) and 89.6% of all patients reported to be satisfied at the final follow-up. Patient satisfaction was negatively correlated with patients’ age (p < 0.05).ConclusionExcellent accuracy regarding component placement in UKA can be achieved with PSI. However, despite excellent survivorship and clinical outcomes, these data indicate that the PSI system is not superior to conventional UKA implantation methods.     

Early prosthetic joint infection: outcomes with debridement and implant retention followed by antibiotic therapy

Recent expert reviews recommend a conservative surgical strategy – debridement and irrigation, antibiotics and implant retention (DAIR) – for most early post-surgical prosthetic joint infections (PJI). However, differences exist in published series regarding success rates with DAIR, and the size of most series is small. In this prospective multicenter cohort study of early PJI managed by DAIR, factors associated with failure of the DAIR were analyzed. Out of 139 early PJI, 117 cases managed with DAIR were studied For 67 patients (57.3%), infection was cured and the implant was salvaged with definite antimicrobial therapy. In 35 (29.9%) DAIR failed and removal of the prosthesis was necessary during follow-up. Finally, 15 patients (12.8%) needed chronic suppressive antimicrobial therapy due to suspected or confirmed persistent infection. Infections due to methicillin-resistant S. aureus (72.7% failed; p 0.05) and those treated at one of the hospitals (80.0% failed; p <0.05) had worse outcomes, but only this last variable was associated with treatment failure following multivariate analysis. Seventy-four per cent of patients who were successfully treated by DAIR and only 32.7% of the failures were able to walk without help or with one stick at the last follow-up visit (p <0.05). In conclusion, a substantial proportion of patients with an early PJI may be successfully treated with DAIR and definite antimicrobial therapy. In more than half of these, the infection can be cured. Since identification of factors associated with failure of DAIR is not simple, we recommend offering DAIR to most patients with early PJI.     

Motivations, satisfaction, and information of immediate breast reconstruction following mastectomy

This study evaluated patients’ motivations for, and satisfaction with, the treatment and information of immediate breast reconstruction (IBR) with a silicone prosthesis. It studied satisfaction more deeply by relating it to the quality of life, body-image and sexual functioning. Seventy-three patients who received mastectomy, followed by IBR with a subpectoral silicone prosthesis, completed a self-report questionnaire concerning their motivations for, perceived advantages of and satisfaction with IBR, the information received, quality of life, body image, and sexual functioning. Despite the fact that 50% of the reconstructions resulted in complications or complaints, 70% of the women were satisfied with the reconstruction and only 12% would never choose IBR again. Satisfaction was strongly correlated with the need for information. The higher the patient’s expectations, the higher their need for information. The most common perceived advantage of IBR was the avoidance of an external prosthesis. A majority of patients were satisfied with the breast reconstruction. However, a sizeable proportion needed more information about breast reconstruction and the use of the silicone prosthesis. To avoid too high expectations more attention should be given to possible complications and the moderate cosmetic results.     

Assessment of the automated multiplex-PCR Unyvero i60 ITI® cartridge system to diagnose prosthetic joint infection: a multicentre study

ObjectivesProsthetic joint infections (PJI) are responsible for significant morbidity and mortality and their number continues to rise. Their management remains complex, especially the microbiological diagnosis. Besides ‘homemade’ tests developed by several teams, new molecular biology methods are now available with different analytical performance and usability.MethodsWe studied the performances of one of these tests: ITI^® multiplex PCR (mPCR) by the Curetis^® company and compared it to either ‘optimized’ culture or 16S rRNA PCR. We performed a retrospective multicentre study to assess the contributions of mPCR in the diagnosis of PJI. We randomly selected 484 intraoperative specimens among 1252 of various types (biopsy, bone, tissue around the prosthesis, synovial fluid) from 251 patients in seven different hospitals. Each sample was treated according to the recommendations of the manufacturer.ResultsIn all, 154 out of 164 (93.9%) samples negative in culture were negative with the mPCR. Among the 276 positive samples in culture, 251 (90.9%) were monomicrobial, of which 119 (47.4%) were positive with the mPCR, and 25 (9.1%) were polymicrobial, of which 12 (48%) were positive with the mPCR. The concordance rate of mPCR with culture was 58.1% (53.6%–62.7%) and the concordance rate with 16S rRNA PCR was 70.1% (65.5%–74.6%).ConclusionThis new standardized molecular test showed a lack of detection when the bacterial inoculum was low (number of positive media per sample and number of colonies per media) but can be useful when patients have received antibiotic therapy previously.     

Prosthetic joint infection of the knee - arthroscopic biopsy identifies more and different organisms than aspiration alone

BackgroundProsthetic joint infection (PJI) causes significant morbidity and mortality following knee replacement surgery. Identifying causative organisms and antibiotic sensitivities is critical in increasing the chance of infection eradication. This study investigated whether biopsy alone was superior to aspiration alone for serological diagnosis in PJI following knee replacement. Secondly, we investigated whether biopsy identifies the same or new/different microbiological flora as aspiration.MethodsSince December 2014, the Exeter Knee Reconstruction Unit (EKRU) has prospectively collated data regarding all PJIs referred from our local/regional network which have been reviewed via our Multi-Disciplinary Team (MDT). We identified and included consecutive patients from this MDT from Dec.2014-Mar.2020 and analysed their electronic records. Statistical analysis was performed using Stata.Results65/100 patients studied had both pre-operative aspiration and biopsy. 31/65 (48%) had positive aspiration and biopsies. No aspirate samples were positive with corresponding biopsies negative. In 19/65 (29%) of infection positive patients, biopsy identified new (7) or additional (12) organisms not identified by aspiration. Aspiration had a sensitivity of 70%, specificity of 88%, positive predictive value of 90.3% and negative predictive value of 64.7%. Biopsy had a sensitivity of 97.5%, specificity of 88%, positive predictive value of 92.9% and negative predictive value of 95.7%.ConclusionIn 29% of confirmed PJI cases, arthroscopic biopsy identified either additional organisms in a polymicrobial PJI when compared to aspiration, or new positive results when aspiration alone was negative. This study demonstrates the benefits of arthroscopic biopsy for serological diagnosis in cases of knee PJI and aids treatment planning.     

BioCartilage augmentation of marrow stimulation procedures for cartilage defects of the knee: Two-year clinical outcomes

BackgroundThe present study evaluated short-term outcomes of microfracture augmented with micronized allograft cartilage matrix (BioCartilage) and platelet-rich plasma (PRP) for symptomatic focal femoral condyle or trochlea cartilage defects.MethodsPatients who underwent microfracture augmented with BioCartilage and PRP for isolated contained chondral defects were evaluated. Magnetic resonance imaging (MRI) was performed at one year postoperatively. Two-year postoperative outcomes included patient-reported outcome measures (PROMs) and rates of return-to-work and return-to-sport.ResultsMean age of the 10 patients who completed the study was 39.7 years (range, 19–66 years), and five (50%) were female. Mean post-debridement defect size of the five femoral condyle and five trochlea defects was 2.4 cm² (range, 0.7–5.0 cm²). One-year postoperative MRI analysis demonstrated that two chondral lesions were < 50% filled, four sites were > 50% filled, two sites were completely filled, and two sites had hypertrophied. Patients experienced improvements in three PROMs at six months, one year, and two years postoperatively (p < 0.01). Postoperative Marx Activity scores revealed no decrease in activity level compared to baseline preoperatively. Nine patients (90%) returned to their pre-injury level of work by one year postoperatively and remained at that level through two years postoperatively.ConclusionsOur findings suggest that small, contained focal chondral injuries in the femoral condyle and trochlea treated with a marrow stimulation procedure augmented with BioCartilage and PRP are associated with significant improvements in patient-reported outcomes at two years postoperatively. Further studies are needed to evaluate the long-term durability and imaging characteristics of this intervention.Level of evidenceTherapeutic Level IV.     

Characteristics and outcome of 27 elbow periprosthetic joint infections: results from a 14-year cohort study of 358 elbow prostheses

Elbow arthroplasty is increasingly performed in patients with rheumatic and post-traumatic arthritis. Data on elbow periprosthetic joint infection (PJI) are limited. We investigated the characteristics and outcome of elbow PJI in a 14-year cohort of total elbow arthroplasties in a single centre. Elbow prosthesis, which were implanted between 1994 and 2007 at Schulthess Clinic in Zurich, were retrospectively screened for infection. PJI was defined as periprosthetic purulence, the presence of sinus tract or microbial growth. A Kaplan–Meier survival method and Cox proportional hazard analysis were performed. Of 358 elbow prostheses, PJI was identified in 27 (7.5%). The median patient age (range) was 61 (39–82) years; 63% were females. Seventeen patients (63%) had a rheumatic disorder and ten (37%) had osteoarthritis. Debridement and implant retention was performed in 78%, followed by exchange or removal of the prosthesis (15%) or no surgery (7%). The relapse-free survival (95% CI) was 79% (63–95%) after 1 year and 65% (45–85%) after 2 years. The outcome after 2 years was significantly better when patients were treated according to the algorithm compared to patients who were not (100% vs. 33%, p <0.05). In 21 patients treated with debridement and retention, the cure rate was also higher when the algorithm was followed (100% vs. 11%, p <0.05). The findings of the present study suggest that the treatment algorithm developed for hip and knee PJI can be applied to elbow PJI. With proper patient selection and antimicrobial therapy, debridement and retention of the elbow prosthesis is associated with good treatment outcome.