Aim. Antimicrobial resistance (AMR) aggravates an already difficult treatment of periprosthetic joint infections (PJI). The prevalence of drug-resistant pathogens varies across countries and increases over time. Regular monitoring of bacteriological analyses should be performed. Due to many factors influencing the AMR, the correct choice of antimicrobial management remains arguable. The primary purpose of this retrospective study was to identify and compare causative bacteria and to compare the incidence of antibiotic resistance between the septic revision total knee arthroplasty (TKA) and septic revision total hip arthroplasty (THA). Method. A review of all revision TKAs and revision THAs, undertaken between 2007 and 2020 in a tertiary referral centre, was performed. Included were cases meeting the consensus criteria for PJI, in which an organism has been identified. There were no major differences in tissue sampling between revision TKAs and revision THAs over time. Results. A total of 228 bacterial strains, isolated after revision TKA and THA, were analysed for their resistance to 20 different antibiotics. There was a statistically significant higher occurrence of Gram-negative bacteria (p=0.002) and Enterococcus species (p=0.026) identified after revision THAs compared to TKA. The comparison of antibiotic resistance between revision TKAs and revision THAs was statistically significant in 9 of 20 analysed antibiotics. Pathogens isolated after revision THA were much more resistant compared to pathogens isolated after revision TKA. Resistance in revision THAs was significantly higher to oxacillin (p=0.03), ciprofloxacin (p<0.001), levofloxacin (p<0.001), moxifloxacin (p=0.005), clindamycin (p<0.001), co-trimoxazole (p<0.001), imipenem (p=0.01), rifampicin (p=0.005) and tetracycline (p=0.009). There was no significantly higher resistance of pathogens isolated after revision TKAs detected. No statistically significant difference in antibiotic resistance of Gram-negative bacteria between revision TKA and revision THA was observed. Conclusions. The occurrence and the resistance of bacteria to antibiotics differs significantly between revision TKAs and revision THAs. This has implications on of the choice of empirical antibiotic in revision surgery as well as prophylactic antibiotic in primary surgery, depending on the joint that is to be replaced

Background. The knowledge about the common mode of failure and each period in primary and revision TKAs offers useful information to prevent those kinds of failure in each surgery. However, there has been limited report that simultaneously compared the mode of failure between primary and revision TKAs using single prosthesis. We compared the survival rate, mode of failure, and periods of each mode of failure between primary and revision TKAs. Methods. A consecutive cohort of 1606 knees (1174 patients) of primary TKA and 258 knees (224 patients) of revision TKA using P.F.C® prosthesis was retrospectively reviewed. The mean follow-up periods of primary and revision TKAs were 10.2 and 10.8 years, respectively. We compared the above variables between primary and revision TKAs. Results. The average 5-, 10-, 15-year survivor rate of primary TKA were 99.1% (CI 95%, ±0.3%), 96.7% (CI 95%, ±0.7%), and 85.4% (CI 95%, ±2.0%). They were 97.8% (CI 95%, ±1.0%), 91.4% (CI 95%, ±2.5%), and 80.5% (CI 95%, ±4.5%) in revision TKA. The common mode of failure included polyethylene wear, loosening, and infection in both primary and revision TKAs. The most common mode of failure was polyethylene wear in primary TKAs and infection in revision TKAs. The mean periods of polyethylene wear and loosening were not significantly different between primary and revision TKAs, but the mean period of infection was significantly long in revision TKA (4.8 years vs. 1.2 years, p=0.003). Conclusions. The survival rate decreased with time, especially after 10 years in both primary and revision TKAs. The continuous efforts are required to prevent and detect various modes of failure during the long-term follow-up after primary and revision TKAs. More careful attention is necessary to detect the late infection as a mode of failure after revision TKA. Level of Evidence. Level III, Therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence

Background. As life expectancy increases, the number of octogenarians requiring primary and revision total knee arthroplasty (TKA) is increasing. Recently, primary TKA has become a common treatment option in octogenarians. However, surgeons are still hesitant about performing revision TKA on octogenarians because of concerning about risk- and cost-benefit. The purpose of this study was to investigate postoperative complications and mid-term survival in octogenarians following primary and revision total knee arthroplasty (TKA). Methods. We retrospectively reviewed 231 primary TKAs and 41 revision TKAs performed on octogenarians between 2000 and 2016. The mean age was 81.9 for primary TKA and 82.3 for revision TKA (p=0.310). The American Society of Anesthesiologists (ASA) score was not different, but the age-adjusted Charlson comorbidity index was higher in revision TKA (4.4 vs. 4.8, p=0.003). The mean follow-up period did not differ (3.8 vs. 3.5 years, p=0.451). The WOMAC scores and range of motion (ROM) were evaluated. The incidence of postoperative complication and survival rate (end point; death determined by telephone or mail communication with patient or family) were investigated. Results. The postoperative WOMAC and ROM were better in primary TKA (33.1 vs. 47.2, p<0.001; 128.9° vs. 113.6°, p<0.001). The most common postoperative complication was delirium in both groups (7.4% vs. 14.6%, p=0.131). There were no differences in the specific complication rates between the two groups. The 5- and 10-year survival rates were 87.2% and 62.9%, respectively, in primary TKA and 82.1% and 42.2%, respectively, in revision TKA (p=0.017). Conclusions. Both primary and revision TKAs are viable options for octogenarians when considering the clinical results and mid-term survival. Delirium needs to be managed appropriately as the most common complication in both primary and revision TKAs for octogenarians

Aim. Despite several synovial fluid biomarkers for diagnosis of periprosthetic joint infection (PJI) have being investigated, point-of-care (POC) tests using these biomarkers are not widely available. Synovial calprotectin has recently been reported to effectively exclude diagnosis of PJI and a novel lateral flow POC test using it has shown potential to be effective. Thus, the aims of this study were to 1) validate calprotectin POC with enzyme linked immunosorbet assay (ELISA) 2) at 2 separate thresholds for PJI diagnosis in total knee arthroplasty (TKA) patients using the 2013 Musculoskeletal Infection Society (MSIS) PJI diagnosis criteria as the gold standard. Method. Intraoperative synovial fluid samples were prospectively collected from 123 patients who underwent revision TKAs (rTKA) at two academic hospitals within the same healthcare system from October 2018 to January 2020. The study was conducted under IRB approval. Included patients followed the hospital standard for their PJI diagnostic work-up. Data collection included demographic, clinical, and laboratory data in compliance with MSIS criteria. Synovial fluid samples were analysed by calprotectin POC and ELISA tests in accordance with manufacturer's instructions. Patients were categorized as septic or aseptic using MSIS criteria by two independent reviewers blinded to calprotectin assay results. The calprotectin POC and ELISA test performance characteristics were calculated with sensitivities, specificities, positive, and negative predicted values (PPV and NPV, respectively) and areas under the curve (AUC) for 2 different PJI diagnosis scenarios: (1) a threshold of >50 mg/L and (2) a threshold of >14 mg/L. Results. According to MSIS criteria, 53 rTKAs were septic while 70 rTKA were aseptic. In the (1) >50 mg/mL threshold scenario, the calprotectin POC and ELISA performance showed 100% agreement with sensitivity, specificity, PPV, NPV, and AUC, respectively, of 98.1%, 95.7%, 94.5%, 98.5%, and 0.969. In the (2) >14 mg/mL threshold scenario, the POC slightly outperformed the ELISA with sensitivity, specificity, PPV, NPV and AUC of 98.1%, 87.1%, 85.2%, 98.4%, and 0.926, respectively (ELISA values were 98.1%, 82.9%, 81.3%, 98.3%, and 0.905, respectively). Conclusions. The calprotectin POC test performed as well as the ELISA at the >50mg/L threshold and was slightly better at the >14 mg/L threshold. The >50 mg/L threshold had a better specificity while maintaining the same sensitivity as the >14 mg/L threshold. This test could be effectively implemented as a rule out test. However, further investigations with larger cohorts are necessary to validate these results

During revision total knee arthroplasty (rTKA), proximal tibial bone loss is frequently encountered and can result in a less-stable bone-implant fixation. A 3D printed titanium alloy (Ti6Al4V) revision augment that conforms to the irregular shape of the proximal tibia was recently developed. The purpose of this study was to evaluate the fixation stability of rTKA with this augment in comparison to conventional cemented rTKA. Eleven pairs of thawed fresh-frozen cadaveric tibias (22 tibias) were potted in custom fixtures. Primary total knee arthroplasty (pTKA) surgery was performed on all tibias. Fixation stability testing was conducted using a three-stage eccentric loading protocol. Static eccentric (70% medial/ 30% lateral) loading of 2100 N was applied to the implants before and after subjecting them to 5×103 loading cycles of 700 N at 2 Hz using a joint motion simulator. Bone-implant micromotion was measured using a high-resolution optical system. The pTKA were removed. The proximal tibial bone defect was measured. One tibia from each pair was randomly allocated to the experimental group, and rTKA was performed with a titanium augment printed using selective laser melting. The contralateral side was assigned to the control group (revision with fully cemented stems). The three-stage eccentric loading protocol was used to test the revision TKAs. Independent t-tests were used to compare the micromotion between the two groups. After revision TKA, the mean micromotion was 23.1μm ± 26.2μm in the control group and 12.9μm ± 22.2μm in the experimental group. There was significantly less micromotion in the experimental group (p= 0.04). Prior to revision surgery, the control and experimental group had no significant difference in primary TKA micromotion (p= 0.19) and tibial bone loss (p= 0.37). This study suggests that early fixation stability of revision TKA with the novel 3D printed titanium augment is significantly better then the conventional fully cemented rTKA. The early press-fit fixation of the augment is likely sufficient for promoting bony ingrowth of the augment in vivo. Further studies are needed to investigate the long-term in-vivo fixation of the novel 3D printed augment

Background. Subvastus approach for Total Knee Arthropalsty (TKA) allows a faster recovery. It is traditionally not utilized for revision surgeries because of difficulty in exposure of the knee and eversion of the patella. It is considered to have limited indications. We hypothesized that revision TKA should not really pose a problem as the exposure gained is adequate with added advantage of preserving the extensor mechanism, thereby allowing faster functional recovery. We present an analysis of the use of subvastus approach for revision TKAs. Materials and methods. 50 patients (50 knees) 37 females + 13 males with mean age 68 years underwent revision total knee arthroplasty (TKA) by subvastus approach between January 2006 to January 2013. All patients were prospectively evaluated by pre- and postoperative Knee Society and function score. The average follow-up was 24 months (range from 1 to 3 years) with minimum 1 year follow-up. The indications for revisions were aseptic loosening (20 knees), infection (12 knees), instability (12 knees) and peri-prosthetic fractures (6 knees). Constrained condylar prosthesis (43 knees), hinged prosthesis (6 knees) and custom made prosthesis (1 knee) were fixed using the subvastus approach. Infected knees underwent one or two staged revisions. Results. The approach provided adequate exposure in all revisions. The average Knee Society score improved from 42 to 83 and the function score from 48 to 65. The complications included medial collateral ligament injury (one case), patellar tendon avulsion (one case) and mal-tracking patella (one case). Average hospital stay was 4 days. Average blood lose was 400 ml. Conclusion. Our results compare favourably with other reported series on revision TKA. The subvastus approach can be considered for revision TKAs

Introduction:. Revision total knee arthroplasty (TKA) can be very complex in nature with difficulties/obstacles involving bone and soft tissue deficits, visualization and exposure, as well as alignment and fixation. Auxiliary devices such as augmentation and offset adapters help address these issues; however they increase the complexity of the reconstruction. The objective of this study was to show that use of a single radius revision TKA system allowing for minimal auxiliary revision devices can yield positive early clinical outcomes. Methods:. This data was collected as part of a prospective, post-market, multicenter study. One hundred and twenty-five single radius revision TKA cases were evaluated. Surgical details were reviewed and cases were grouped based on type of auxiliary devices used. Group 1 included cases that used only femoral and/or tibial augments. Group 2 used femoral and/or tibial augments in conjunction with femoral and/or tibial offset adapters. Early clinical outcomes, operative data and radiographic findings were used to compare cases. Results:. At 6 weeks and 1 year postoperatively, Knee Society Scores, pain, function and quality of life all improved more in Group 1 (augments only) than Group 2 (augments and offset adapters). There was no difference in range of motion postoperatively for either group. Preoperative demographics showed no differences between Group 1 and Group 2. Offset adapters were used in only 17.6% of the cases. Discussion/Conclusion:. Studies have discussed the increase in complexity of revision TKAs is associated with a decrease in patient outcomes. The surgical technique for revision TKAs can be more difficult due to an increase in bone loss and anatomical changes. Augment usage is the main auxiliary component utilized to supplement bone loss. By design, this single radius revision system limits the additional need for offset adapters to adjust patient alignment, while achieving excellent postoperative patient outcomes. Reducing the amount of devices needed for reconstruction decreases the intraoperative complexity and has shown improved functional outcomes with this single radius revision TKA system

Nutritional Status and Short-Term Outcomes Following THA; Initial Metal Ion Levels Predict Risk in MoM THA; THA Bearing Surface Trends in the US ‘07- ’14; Dislocation Following Two-Stage Revision THA; Timing of Primary THA Prior to or After Lumbar Spine Fusion; Failure Rate of Failed Constrained Liner Revision; ESR and CRP vs. Reinfection Risk in Two-Stage Revision?; Mechanical Complications of THA Based on Approach; Impaction Force and Taper-Trunnion Stability in THA; TKA in Patients Less Than 50 Years of Age; Post-operative Mechanical Axis and 20-year TKA Survival and Function; Return to Moderate to High-intensity Sports after UKA; “Running Two Rooms” and Patient Safety in TJA; Varus and Implant Migration and Contact Kinematics after TKA; Quadriceps Snips in 321 Revision TKAs; Tubercle Proximalization for Patella Infera in Revision TKA; Anterior Condylar Height and Flexion in TKA; Compression Bandage Following Primary TKA; Unsupervised Exercise vs. Traditional PT After Primary TKA and UKA

Introduction. Within the reconstruction of unicondylar femoral bone defects with morselized bone grafts in revision total knee arthroplasty (TKA), a stem extension appears to be critical to obtain adequate mechanical stability. Whether the stability is still secured by this reconstruction technique in bicondylar defects has not been assessed. Long, rigid stem extensions have been advocated to maximize the stability in revision TKAs. The disadvantage of relatively stiff stem extensions is that bone resorption is promoted due to stress shielding. Therefore, we developed a relatively thin intramedullary stem which allowed for axial sliding movements of the articulating part relative to the intramedullary stem. The hypothesis behind the design is that compressive contact forces are directly transmitted to the distal femoral bone, whereas adequate stability is provided by the sliding intramedullary stem. A prototype was made of this new knee revision design and applied to the reconstruction of uncontained bicondylar femoral bone defects. Materials and Methods. Five synthetic distal femora with a bicondylar defect were reconstructed with impacted bone grafting (IBG) and this new knee revision design. A custom-made screw connection between the stem and the intercondylar box was designed to lock or initiate the sliding mechanism, another screw (dis)connected the stem. A cyclically axial load of 500 N was applied to the prosthetic condyles to assess the stability of the reconstruction. Radiostereometry was used to determine the migrations of the femoral component with a rigidly connected stem, a sliding stem and no stem extension. Results. We found a stable reconstruction of the bicondylar femoral defects with IBG in case of a rigidly connected stem. After disconnecting the stem, the femoral component showed substantially more migrations. With a sliding stem rotational migrations were similar to those of a rigidly connected stem. However, the sliding stem allowed proximal migration of the condylar component, thereby compressing the IBG. Discussion. A stable reconstruction of uncontained bicondylar femoral defects could be created with IBG and a TKA with a thin stem extension. It appeared that the presence of a functional stem extension was important for the stability of the bicondylar reconstruction. In an effort to reduce stress shielding, we developed a sliding stem mechanism. This sliding stem provided adequate stability, while compressive contact forces are still transmitted to the distal femoral bone. Clinical studies have to confirm that our sliding stem mechanism leads to long term bone maintenance after revision TKAs

Background. Periprosthetic joint infection (PJI) after knee arthroplasty surgery remains a serious complication. Yet, there is no international consensus on the surgical treatment of PJI. The purpose was to assess the prosthesis survival rates, risk of re-revision, and mortality rate following the different surgical strategies (1-stage or 2-stage implant revision, and irrigation and debridement (IAD) with implant retention) used to treat PJI. Methods. The study was based on 653 total knee arthroplasties (TKAs) revised due to PJI in the period 1994 to 2016. Kaplan-Meier (KM) and multiple Cox regression analyses were performed to assess the survival rate of these revisions and the risk of re-revisions. We also studied the mortality rates at 90 days and 1 year after revision for PJI. Results. Of the 653 revision TKAs; 329, 81, and 243 revisions were performed with IAD, 1-stage, and 2-stage revision procedures, respectively. During the follow-up period, 19%, 12.3% and 11.5% of the IAD, 1-stage, and 2-stage revision cases were re-revised due to PJI, respectively. With any reasons of re-revision as end-point the 5 year KM survival of the index revision procedure was 76%, 82%, and 84% after IAD, 1-stage, and 2-stage revision, respectively. Similarly, the 5-year KM survival with a re-revision for infection as end-point was 79%, 88%, and 87% after IAD, 1-stage, and 2-stage revision, respectively. There were no statistically significant differences between 1-stage and 2-stage revision for re-revision of any reasons (RR=1.6; 95% CI: 0.8–3.1) nor did we find a difference for re-revision due to deep infection (RR=1.4; 95% CI: 0.6–3.1) as end-point. In an age-stratified analysis, however, the risk of re-revision for any causes was 4 times increased after 1-stage revision compared to 2-stage revision in patients over 70 years of age (RR=4.2, 95% CI: 1.3–13.7) but the risk was similar for deep infection as end-point. Age had no statistically significant effect on the risk of re-revision for knees revised with the IAD procedure. The 90-days and 1-year mortality rate after revision for PJI were 2.1% and 3.6% after IAD, 1.2% and 1.2% after 1-stage revision, and 0.4% and 1.6% after 2-stage revision and there were no statistically significant differences in mortality rate according to revision procedure. Conclusion. IAD had good results compared to earlier published studies. Despite that 1-stage revisions had a 4 times higher risk for re-revision compared to 2-stage revisions in older patients, the overall outcomes after 1-stage and 2-stage revision were similar

Introduction. Computed tomography (CT) based preoperative planning provides useful information for severe TKA and revision TKA cases, such as the amount of augmentation, length of stem extension and component alignment, to achieve correct alignment and joint line. In this study, we evaluated TKA alignment performed with CT preoperative planning. Materials and Methods. 7 primary TKAs for severe deformity and 3 revision TKAs were included. CT preoperative planning was performed with JIGEN (LEXI, Japan). Constrained condylar prosthesis (LCCK, Zimmer) were used in all case. For femoral component, axial alignment was decided by controlled IM rod insertion to femoral canal. Rotational alignment was decided according to anterior cortex that usually was not compromised. For tibial component, axial alignment was set to perpendicular to tibial mechanical axis. Coverage and joint line level were carefully decided. The amount of bone resection of bilateral distal and posterior femoral condyle and proximal tibia was measured, respectively. Stem extension length and offset were selected according to components position and canal filling. Amount of augmentation was also estimated bilateral distal and posterior femoral condyle, respectively. Postoperative component alignment was evaluated three-dimensionally with Knee-CAS (LEXI, Japan). Results. All femoral and tibial components were implanted within 5°in coronal and sagittal plane. All knees showed mechanical alignment within 5 degree from neutral. One of 10 TKAs needed femoral component size down, and two of 20 stems needed size change

The National Joint Registry (NJR) for England & Wales provides a useful reference for hospitals to assess and compare their current practice with national figures. We aimed to identify patient and surgical factors at time of primary total knee arthroplasty (TKA) responsible for the revision. A retrospective case note review was performed of all revision TKAs performed at Musgrove Park Hospital 2005–2010. Exclusion criteria included primary TKA performed elsewhere. 38 TKAs and 13 unicompartmental knee arthroplasties (UKAs) were revised. Mean time to revision was 1.8 years and 2.1 years respectively. Reason for revision was pain or disease progression in 54% revised UKAs and infection in 53% revised TKAs. 35% infected cases were therapeutically anticoagulated, 75% ASA 3 and 50% had a BMI >30. No problems were identified with surgeon grade or level of supervision. 5 cases of revision were of a trial primary prosthesis. There were large numbers of high risk patients (increased BMI, ASA grade or on anticoagulants), which may contribute to increased infection rates and subsequent revision. We suggest avoiding trial prostheses and recommend delaying anticoagulation reintroduction until the wound is fully healed. This information may be useful for aiding with patient selection and consent

Introduction. Modular stems are commonly used to improve fixation in revision total knee arthroplasty (TKA). Hybrid fixation, in which cement is placed around the metaphysical portion of the component combined with an uncemented diaphyseal modular stem, has potential advantages including ease of insertion, improved component alignment, and ease of removal if needed. The aim of this study was to evaluate clinical results of revision total knee arthroplasty with uncemented modular stems using a hybrid fixation technique with a minimum 5-year follow-up. Methods. 23 revision TKAs were performed in 21 patients with hybrid fixation using uncemented modular stems. 3 patients (3 knees) had died of causes unrelated to the index arthroplasty at the time of the study, and 1 patient (1 knee) was lost to the follow-up. The remaining 19 knees were clinically and radiographically evaluated for the present study. The average follow-up time was 9.5 years. The average age of the patients was 70.5 years at the time of the revision surgery. The average time between the primary and revision surgeries was 10.6 years. Results. The reasons for the revision of the 19 knees were aseptic loosening in 14 knees and breakage of polyethylene or implant in 5 knees. The mean postoperative range of motion was 110.2 degrees at the time of the most recent follow-up. The mean postoperative knee and function scores were 80.6 and 50.8, respectively. Periprosthetic radiolucencies were found adjacent to 2 tibial components and an asymptomatic cortical thickening around the end-of-stem was found in 1 tibial component. There were no intra- or postoperative complications resulting from the prosthesis implantation with this technique. Discussion. Revision TKA with hybrid fixation demonstrated excellent clinical results in terms of survival rate at a minimum 5-year follow-up. Although the ideal fixation of modular stems in revision TKA remains unclear, this study demonstrated that hybrid fïxation can be a viable option to provide durable fixation

Introduction. Revision Total Knee Arthroplasty (TKA) is becoming increasingly prevalent as the number of TKA procedures grow in a younger, higher-demand population. Factors associated with patients requiring multiple revision TKAs are not yet well understood. The purpose of this study is to investigate the epidemiology of re-revision TKA, and identify risk factors that are associated with failure of re-revision TKA. Methods. A retrospective analysis was performed on 358 patients who underwent revision TKA at a single institution between 1/2012 and 12/2013. Patients who underwent revision knee arthroplasty two or more times were included. Patients were excluded if their indication for the first revision was periprosthetic joint infection (PJI). Patient demographics, surgical indications, revision details, and available follow-up information were collected. Re-revision failure was defined as the need for any additional operative intervention. A logistic regression analysis was performed to assess for significant predictors of re-revision failure. Results. A total of 66 re-revision TKA patients were included in this study. Mean age at re-revision was 60 (±11 years). There were 48 (73%) females. Mean BMI was 31.8 (±6.9). Median ASA level was 2 (40/59; 68%). Average follow up was 2.1 (±1.0) years, with 68% (45/66) of patients having greater than 2 year follow up (Table 1). The median number of revisions was 2 (range 2–11). The most common indication for re-revision was arthrofibrosis (15; 23%), followed by PJI (14; 21%) and aseptic component loosening (13; 20%). Among re-revision patients, the most common indication of the first revision was aseptic component loosening (17; 30%), followed by arthrofibrosis (16; 28%) and instability (9; 16%) (Table 2). Among the top four indications for re-revision, both the re-revision and initial revision indication were the same. Additionally, 42% of patients possessed the same indication for re-revision as the initial revision. The proportion of patients that had a lateral release performed in either the index procedure or initial revision was higher in re-revisions performed for patellar maltracking (p=0.013). There was a significantly increased risk of re-revision failure if the patient had a higher BMI (OR=1.22; p=0.006). Re-revision survival at 30 days was 92% (60/65), at 1 year was 81% (52/64), and at 2 years 73% (33/45). The indication history of re-revision failure is shown on Table 3. Discussion. Arthrofibrosis and PJI were the most common indications for re-revision. There was an increased risk of re-revision failure in patients with a higher BMI. It was common to have a re-revision TKA for the same indication as the initial revision. A better understanding of the indications and patient factors that are associated with re-revision failures can help align surgeon and patient expectations in this challenging population. For any figures or tables, please contact authors directly (see Info & Metrics tab above).

Recent analyses of failure mechanisms continue to show aseptic loosening as the predominant mechanism of total knee arthroplasty (TKA) failure. Evaluation for aseptic loosening begins with careful assessment of plain films radiographs, however the utility of examining lucent lines under a cemented tibial tray remains unclear. The purpose of this study is to examine the distribution of lucent lines under cemented tibial components on single-series anteroposterior (AP) and lateral plain radiographs and to determine their significance in the prediction of aseptic loosening found during revision TKA surgery. Retrospective chart and radiographic review of all patients that underwent revision TKA between 2001–2014 at a single academic hospital center. Revision TKA for periprosthetic fracture, stem fracture, implant dissociation and periprosthetic joint infection were excluded. The most recent pre-revision surgery AP and lateral knee radiographs were assessed by two fellowship trained adult reconstruction surgeons blinded to patient demographics and intraoperative details. Lucent lines under the tibia tray defined as >2mm were documented according to the new KSS radiographic scoring system. Demographic details and the surgeon's assessment whether the tibia tray was loose intraoperatively were extracted from chart review and the operative note, respectively. Univariate and multivariable logistic regression modeling was used to predict the outcome of aseptic loosening. Between 2001 and 2014, 312 revision TKAs were performed that met our inclusion criteria. Of these, 84 (26.9%) had intraoperative loose tibia trays. We observed a significantly increased risk of aseptic tibia loosening among older patients at time of surgery (odds ratio [OR] 1.05, 95% CI 1.02, 1.08). Posterior stabilised primary TKA components conferred a significantly decreased risk of aseptic tibia loosening (OR 0.36, 95% 0.21, 0.60). On an AP radiograph, after adjustment for other zones, the presence of a lucent line in zone 1, 2 or 3 were all significantly associated with tibia loosening, OR 7.35, 8.69 and 22.26 (p<0.0001) respectively. On a lateral radiograph, after adjustment for other zones, the presence of a lucent line in zone 1, 2 or 3 were all significantly associated with tibia loosening, OR 12.89, 18.03, and 11.63 (p<0.004) respectively. The complete absence of lucent lines under a tibia tray on an AP or lateral radiograph were associated with 96% (CI 0.02, 0.07) and 95% (CI 0.02, 0.09) reduced odds of aseptic tibia loosening. Careful examination of lucent lines under a tibia component can be highly predictive of aseptic loosening. The areas associated with highest risk of tibia loosening occur in zone 3 on the AP radiograph (medial or lateral to the keel) and zone 2 on the lateral radiograph (posteriorly). The risk of loosening in the absence of lucent line findings on plain films is significantly low

Purpose. To identify the modes of failure after total knee arthroplasty (TKA) in patients ≤ 55 years of age and to compare with those ≥ 56 years of age in patients who underwent revision TKA. Materials and Methods. We retrospectively reviewed 256 revision TKAs among patients who underwent TKA for knee osteoarthritis between January 1992 and December 2012. The causes of TKA failure were analyzed and compared between those ≤ 55 years of age and those ≥ 56 years of age. The age at the time of primary surgery was ≤ 55 years in 30 patients (31 knees) and ≥ 56 years in 210 patients (225 knees). Results. A total of 453 TKAs were performed in ≤ 55-year-old patients between 1992 and 2012. Of these, 31 cases (7%) were revised. Their mean age was 50.6 years (range, 40 to 55 years) at primary surgery and the interval from primary TKA to revision was 8.6 years (range, 1 to 17 years). In the ≤ 55 years of age group, the most common modes of TKA failure was polyethylene wear in 14 cases (45%) followed by infection in 8 cases (26%) and component loosening in 5 cases (17%). The other conditions led to TKA failure were stiffness, periprosthetic fracture, malalignment, and osteolysis in one case each (3%). Of the 11,363 TKAs that were performed in ≥ 56-year-old patients, 225 cases (2%) required a revision. The mean interval between the operations was 5.3 years (range, 0.1 to 18 years). The major modes of failure of primary TKA include polyethylene wear in 99 cases (44%), infection in 91 cases (40%), and component loosening in 26 cases (12%). In both groups, the most common cause of failure was polyethylene wear, which was followed by infection and component loosening. There were relatively lower infection rate and higher loosening rate in patients ≤ 55 years of age, but the difference was not statistically significant (p > 0.05). The mean interval between the operations was shorter in the ≥ 56 years of age group (5.3 years; range, 0.1 to 18 years) than in the younger patient group (8.6 years; range, 1 to 17 years), but there was no notable intergroup difference (p > 0.05). Conclusion. The main modes of failure after TKA in patients ≤ 55 years of age were polyethylene wear, infection and loosening, and there was no significant difference in the modes of failure after TKA between the two groups

Introduction:. Non-cemented, porous-coated metaphyseal sleeves have been designed to improve biologic fixation and stability in revision total knee arthroplasty (TKA) with major bone defects. The aim of this study was to evaluate the clinical results and osteointegration of these sleeves in major bone loss. Materials and Methods:. Between 2008 and 2011, 24 revision TKAs with major bone loss were reconstructed with non-cemented, porous-coated proximal sleeve (DePuy, Warsaw, IN). All patients were prospectively followed for a minimum of 2 years. Indications for use of sleeves were major metaphyseal tibial and femoral bone loss, younger age, and higher activity level. Osteointegration around the sleeves were classified as: . –. Grade 1: Complete osteointegration in all views without any demarcation. –. Grade 2: Sleeves that are not completely osteointegrated but they are stable. Grade 2A: Demarcation less than 2 mm on any view. Grade 2B: Demarcation more than 2 mm on any view . –. Grade 3: Sleeves that are not osteointegrated and unstable with evidence of subsidence. Grade 3A: Subsidence less than 2 mm on any view. Grade 3B: Subsidence more than 2 mm on any view. Results:. Mean range of motion and Knee Society Scores were 108 degrees and 92 respectively. 14 cases were revised for aseptic loosening and 10 cases for infection (which were treated with two stage revision arthroplasty). There was no malalignment, subsidence or re-revision at final follow-up. All sleeves were osteointegrated with majority grade 1 or 2a. Discussion and conclusion:. Short-term results of non-cemented metaphyseal sleeves in major bone loss for loosening of infection demonstrated excellent clinical results and osteointegration

1) INTRODUCTION. Total knee arthroplasty (TKA) is one of the most common orthopaedic procedures performed, and is projected to exponentially increase over the next 20 years. As primary TKA cases increase, so does the frequency of revisions. The primary goals for all TKA cases include alleviating pain and improving overall knee function. The objective of this study was to evaluate the change in outcomes as measured by the Knee Society Score (KSS) between primary and revision TKA systems. 2) METHODS. This data was collected as part of three prospective, post-market, multicenter studies comparing preoperative to 6-week data. Patients were stratified into two groups based on type of single radius knee device; Posteriorly Stabilized (PS) group and Total Stabilizer (TS) group. Early clinical outcomes based on the KSS and operative data were used to compare groups. 3) RESULTS. The KSS was compared to determine the amount of improvement in revision vs. primary cases. Within the KSS Pain/Motion section, the improvement in range of motion was greatest in the TS revision group (change of 8°) in comparison to the primary PS group (change of 3°), as well as a significant decrease in pain classification. The KSS Functional scores improved significantly more in the revision group compared to the primary group. 4) DISCUSSION and CONCLUSION. Studies have determined that revision TKAs have lower rates of functional outcomes, leading to a decreasing trend in KSS. This trend can be correlated to increased difficulty of the surgical technique due to increased bone loss and anatomical changes, as well as a higher constraint in revision TKA devices. The design of a single radius knee revision system addresses these issues with revision TKA and has been shown to have comparable KSS evaluations to patients receiving primary single radius TKAs

Introduction. Even a number of studies have reported clinical outcomes after revision total knee arthroplasty (revision TKA), little information is still available on whether outcomes of patients undergoing a revision TKA as a second stage procedure because of infected TKA are poorer than those of the patients undergoing a single-stage revision TKA because of non-infectious causes. In addition, use of various revision prostheses in most previous studies may limit solid interpretation of the outcomes after revision TKA. This study sought to determine whether outcomes in patients undergoing revision TKA due to infected TKA would be different from those in patients undergoing revision TKA due to non-infectious causes. Materials and Methods. We assessed 71 cases undergoing revision TKAs with use of a same revision system (Scorpio TS®, Stryker, Mahwah, NJ) from October 1999 to February 2012. All patients followed more than two years and mean follow-up period was 67 months (range: 24 – 168 months). Of them, thirty five patients underwent revisions due to infected TKA (group for infected TKA) while 36 patients due to non-infectious causes including loosening, wear, and/or instability (group for non-infected TKA). All patients in the group for infected TKA underwent two-stage revision surgeries while all patients in the group for non-infected TKA single stage revision surgeries. Comparative variables between two groups were preoperative range of motion (ROM) and American knee society (AKS) scores, postoperative ROM and AKS scores assessed at latest follow-up, amount of bone loss and requirement of stem assessed during the surgeries, and survival rate. Results. Preoperatively, the group for infected TKA showed significantly poorer range of motion (102° vs. 112°, P = 0.011) and knee society knee scores (58 vs. 67 points, P = 0.02) than the group for non-infected TKA. During operation, stem for femoral component was more frequently used in the group for infected TKA than the group for non-infected TKA (71% vs. 42%, P = 0.009). Postoperatively, the group for infected TKA still showed significantly poorer range of motion (115° vs. 122°, P = 0.015) and trend of poorer knee society knee scores (83 vs. 89 points, P = 0.054). However, there were no significant differences in amounts of improvement of the ROM and AKS scores, and survival rate between the two groups. Conclusion. The patients undergoing revision TKA as a two-stage procedure due to infected primary TKA showed significantly poorer pre- / postoperative range of motion and poorer preoperative clinical scores, and trend of poorer postoperative scores than those undergoing single stage revision TKA due to non-infectious causes. Nevertheless, the amounts of improvement of the clinical values and survival rate were not different between the two groups. Our findings suggest that even the group for infected TKA had inferior postoperative outcomes than the group for non-infected TKA, the inferior outcomes seems to stem from poorer preoperative outcomes of the group for infected TKA

Purpose. Two-stage re-implantation after infection of Total Knee Arthroplasty (TKA), remains the gold standard to which other forms of treatment should be compared. The primary purpose of this study was to determine the rates of failure and functional outcome of two stage revision TKA for treatment of infection comparing cemented posterior stabilized compared to constrained condylar implants. Method. The study group included 25 consecutive patients who had two stage revision TKA to treat infection with an average follow up of 3.25 1.5 years (range 2–6). In all patients the diagnosis of infection was made using standard serum parameters as well as aspiration for joint fluid analysis. Eight patients had posterior stabilized TKAs and 17 patients with had constrained condylar TKAs. Clinical evaluation included the Knee Society Knee Scores (KSKS) at each follow-up visit as well as a detailed record of any difficulties or complications. Results. No patient (8/8) in the LPS posterior stabilized group and 16 of 17 (94.1%) patients in the LCCK constrained condylar group, had any complaint indicative of instability. Two patients (8%) had re-infection (1 in each group). There was no significant difference between the knee scores (p=0.64) and function scores (p=0.38) of the LPS posterior stabilized and LCCK constrained condylar groups at latest follow up. Conclusion. Our findings suggest that the strategy of using the least constrained implants that provide adequate stability as judged intra-operatively is appropriate also in 2 stage revision TKAs for infection