Worldwide rates of primary and revision total knee arthroplasty (TKA) are rising due to increased longevity of the population and the burden of osteoarthritis. Revision TKA is a technically demanding procedure generating outcomes which are reported to be inferior to those of primary knee arthroplasty, and with a higher risk of complication. Overall, the rate of revision after primary arthroplasty is low, but the number of patients currently living with a TKA suggests a large potential revision healthcare burden. Many patients are now outliving their prosthesis, and consideration must be given to how we are to provide the necessary capacity to meet the rising demand for revision surgery and how to maximise patient outcomes. The purpose of this review was to examine the epidemiology of, and risk factors for, revision knee arthroplasty, and to discuss factors that may enhance patient outcomes. Cite this article: Bone Joint J 2015; 97-B:723–8

Aims. We have previously reported the mid-term outcomes of revision total knee arthroplasty (TKA) for flexion instability. At a mean of four years, there were no re-revisions for instability. The aim of this study was to report the implant survivorship and clinical and radiological outcomes of the same cohort of of patients at a mean follow-up of ten years. Methods. The original publication included 60 revision TKAs in 60 patients which were undertaken between 2000 and 2010. The mean age of the patients at the time of revision TKA was 65 years, and 33 (55%) were female. Since that time, 21 patients died, leaving 39 patients (65%) available for analysis. The cumulative incidence of any re-revision with death as a competing risk was calculated. Knee Society Scores (KSSs) were also recorded, and updated radiographs were reviewed. Results. The cumulative incidence of any re-revision was 13% at a mean of ten years. At the most recent-follow-up, eight TKAs had been re-revised: three for recurrent flexion instability (two fully revised to varus-valgus constrained implants (VVCs), and one posterior-stabilized (PS) implant converted to VVC, one for global instability (PS to VVC), two for aseptic loosening of the femoral component, and two for periprosthetic joint infection). The ten-year cumulative incidence of any re-revision for instability was 7%. The median KSS improved significantly from 45 (interquartile range (IQR) 40 to 50) preoperatively to 70 (IQR 45 to 80) at a mean follow-up of ten years (p = 0.031). Radiologically, two patients, who had not undergone revision, had evidence of loosening (one tibial and one patellar). The remaining components were well fixed. Conclusion. We found fair functional outcomes and implant survivorship at a mean of ten years after revision TKA for flexion instability with a PS implant. Recurrent instability and aseptic loosening were the most common indications for re-revision. Components with increased constraint, such as a VVC or hinged, should be used in these patients in order to reduce the risk of recurrent instability. Cite this article: Bone Joint J 2022;104-B(10):1126–1131

Aims. Stemmed tibial components are frequently used in revision total knee arthroplasty (TKA). The purpose of this study was to evaluate patient satisfaction, overall pain, and diaphyseal tibial pain in patients who underwent revision TKA with cemented or uncemented stemmed tibial components. Methods. This is a retrospective cohort study involving 110 patients with revision TKA with cemented versus uncemented stemmed tibial components. Patients who underwent revision TKA with stemmed tibial components over a 15-year period at a single institution with at least two-year follow-up were assessed. Pain was evaluated through postal surveys. There were 63 patients with cemented tibial stems and 47 with uncemented stems. Radiographs and Knee Society Scores were used to evaluate for objective findings associated with pain or patient dissatisfaction. Postal surveys were analyzed using Fisher’s exact test and the independent-samples t-test. Logistic regression was used to adjust for age, sex, and preoperative bone loss. Results. No statistically significant differences in stem length, operative side, or indications for revision were found between the two cohorts. Tibial pain at the end of the stem was present in 25.3% (16/63) of cemented stems and 25.5% (12/47) of uncemented stems (p = 1.000); 74.6% (47/63) of cemented patients and 78.7% (37/47) of uncemented patients were satisfied following revision TKA (p = 0.657). Conclusion. There were no differences in patient satisfaction, overall pain, and diaphyseal tibial pain in cemented and uncemented stemmed tibial components in revision TKA. Patient factors, rather than implant selection and surgical technique, likely play a large role in the presence of postoperative pain. Stemmed tibial components have been shown to be a possible source of pain in revision TKA. There is no difference in patient satisfaction or postoperative pain with cemented or uncemented stemmed tibial components in revision TKA. Cite this article: Bone Joint J 2021;103-B(6 Supple A):165–170

Introduction. The primary aim of this study was to describe a baseline comparison of early knee-specific functional outcomes following revision total knee arthroplasty (TKA) using metaphyseal sleeves with a matched cohort of patients undergoing primary TKA. The secondary aim was to compare incidence of complications and length of stay (LOS) between the two groups. Methods. Patients undergoing revision TKA for all diagnoses between 2009 and 2016 had patient-reported outcome measures (PROMs) collected prospectively. PROMs consisted of the American Knee Society Score (AKSS) and Short-Form 12 (SF-12). The study cohort was identified retrospectively and demographics were collected. The cohort was matched to a control group of patients undergoing primary TKA. Results. Overall, 72 patients underwent revision TKA and were matched with 72 primary TKAs with a mean follow-up of 57 months (standard deviation (SD) 20 months). The only significant difference in postoperative PROMs was a worse AKSS pain score in the revision group (36 vs 44, p = 0.002); however, these patients still produced an improvement in the pain score. There was no significant difference in improvement of AKSS or SF-12 between the two groups. LOS (9.3 days vs 4.6 days) and operation time (1 hour 56 minutes vs 1 hour 7 minutes) were significantly higher in the revision group (p < 0.001). Patients undergoing revision were significantly more likely to require intraoperative lateral release and postoperative urinary catheterisation (p < 0.001). Conclusion. This matched-cohort study provides results of revision TKA using modern techniques and implants and outlines what results patients can expect to achieve using primary TKA as a control. This should be useful to clinicians counselling patients for revision TKA

Aims. This study aimed to determine outcomes of isolated tibial insert exchange (ITIE) during revision total knee arthroplasty (TKA). Methods. From 1985 to 2016, 270 ITIEs were performed at one institution for instability (55%, n = 148), polyethylene wear (39%, n = 105), insert fracture/dissociation (5%, n = 14), or stiffness (1%, n = 3). Patients with component loosening, implant malposition, infection, and extensor mechanism problems were excluded. Results. Survivorship free of any re-revision was 68% at ten years. For the indication of insert wear, survivorship free of any re-revision at ten years was 74%. Re-revisions were more frequent for index diagnoses other than wear (hazard ratio (HR) 1.9; p = 0.013), with ten-year survivorships of 69% for instability and 37% for insert fracture/dissociation. Following ITIE for wear, the most common reason for re-revision was aseptic loosening (33%, n = 7). For other indications, the most common reason for re-revision was recurrence of the original diagnosis. Mean Knee Society Scores improved from 54 (0 to 94) preoperatively to 77 (38 to 94) at ten years. Conclusion. After ITIE, the risk and reasons for re-revision correlated with preoperative indications. The best results were for polyethylene wear. For other diagnoses, the re-revision rate was higher and the failure mode was most commonly recurrence of the original indication for the revision TKA. Cite this article: Bone Joint J 2021;103-B(6):1103–1110

Aims. Tibial tubercle osteotomy (TTO) facilitates surgical exposure and protects the extensor mechanism during revision total knee arthroplasty (rTKA). The purpose of this study was to determine the rates of bony union, complications, and reoperations following TTO during rTKA, to assess the functional outcomes of rTKA with TTO at two years’ minimum follow-up, and to identify the risk factors of failure. Methods. Between January 2010 and September 2020, 695 rTKAs were performed and data were entered into a prospective database. Inclusion criteria were rTKAs with concomitant TTO, without extensor mechanism allograft, and a minimum of two years’ follow-up. A total of 135 rTKAs were included, with a mean age of 65 years (SD 9.0) and a mean BMI of 29.8 kg/m. 2. (SD 5.7). The most frequent indications for revision were infection (50%; 68/135), aseptic loosening (25%; 34/135), and stiffness (13%; 18/135). Patients had standardized follow-up at six weeks, three months, six months, and annually thereafter. Complications and revisions were evaluated at the last follow-up. Functional outcomes were assessed using the Knee Society Score (KSS) and range of motion. Results. The mean follow-up was 51 months (SD 26; 24 to 121). Bony union was confirmed in 95% of patients (128/135) at a mean of 3.4 months (SD 2.7). The complication rate was 15% (20/135), consisting of nine tibial tubercle fracture displacements (6.7%), seven nonunions (5%), two delayed unions, one tibial fracture, and one wound dehiscence. Seven patients (5%) required eight revision procedures (6%): three bone grafts, three osteosyntheses, one extensor mechanism allograft, and one wound revision. The functional scores and flexion were significantly improved after surgery: mean KSS knee, 48.8 (SD 17) vs 79.6 (SD 20; p < 0.001); mean KSS function, 37.6 (SD 21) vs 70.2 (SD 30; p < 0.001); mean flexion, 81.5° (SD 33°) vs 93° (SD 29°; p = 0.004). Overall, 98% of patients (n = 132) had no extension deficit. The use of hinge implants was a significant risk factor for tibial tubercle fracture (p = 0.011). Conclusion. TTO during rTKA was an efficient procedure to improve knee exposure with a high union rate, but had significant specific complications. Functional outcomes were improved at mid term. Cite this article: Bone Joint J 2023;105-B(10):1078–1085

The demand for revision total knee arthroplasty (TKA) has grown significantly in recent years. The two major fixation methods for stems in revision TKA include cemented and ‘hybrid’ fixation. We explore the optimal fixation method using data from recent, well-designed comparative studies. We performed a systematic review of comparative studies published within the last 10 years with a minimum follow-up of 24 months. To allow for missing data, a random-effects meta-analysis of all available cases was performed. The odds ratio (OR) for the relevant outcome was calculated with 95% confidence intervals. The effects of small studies were analyzed using a funnel plot, and asymmetry was assessed using Egger's test. The primary outcome measure was all-cause failure. Secondary outcome measures included all-cause revision, aseptic revision and radiographic failure. There was a significantly lower failure rate for hybrid stems when compared to cemented stems (p = 0.006) (OR 0.61, 95% CI 0.42-0.87). Heterogeneity was 4.3% and insignificant (p = 0.39). There was a trend toward superior hybrid performance for all other outcome measures including all-cause re-revision, aseptic re-revision and radiographic failure. Recent evidence suggests a significantly lower failure rate for hybrid stems in revision TKA. There is also a trend favoring the use of hybrid stems for all outcome variables assessed in this study. This is the first time a significant difference in outcome has been demonstrated through systematic review of these two modes of stem fixation. We therefore recommend the use, where possible, of hybrid stems in revision TKA

Aims. Obtaining solid implant fixation is crucial in revision total knee arthroplasty (rTKA) to avoid aseptic loosening, a major reason for re-revision. This study aims to validate a novel grading system that quantifies implant fixation across three anatomical zones (epiphysis, metaphysis, diaphysis). Methods. Based on pre-, intra-, and postoperative assessments, the novel grading system allocates a quantitative score (0, 0.5, or 1 point) for the quality of fixation achieved in each anatomical zone. The criteria used by the algorithm to assign the score include the bone quality, the size of the bone defect, and the type of fixation used. A consecutive cohort of 245 patients undergoing rTKA from 2012 to 2018 were evaluated using the current novel scoring system and followed prospectively. In addition, 100 first-time revision cases were assessed radiologically from the original cohort and graded by three observers to evaluate the intra- and inter-rater reliability of the novel radiological grading system. Results. At a mean follow-up of 90 months (64 to 130), only two out of 245 cases failed due to aseptic loosening. Intraoperative grading yielded mean scores of 1.87 (95% confidence interval (CI) 1.82 to 1.92) for the femur and 1.96 (95% CI 1.92 to 2.0) for the tibia. Only 3.7% of femoral and 1.7% of tibial reconstructions fell below the 1.5-point threshold, which included the two cases of aseptic loosening. Interobserver reliability for postoperative radiological grading was 0.97 for the femur and 0.85 for the tibia. Conclusion. A minimum score of 1.5 points for each skeletal segment appears to be a reasonable cut-off to define sufficient fixation in rTKA. There were no revisions for aseptic loosening at mid-term follow-up when this fixation threshold was achieved or exceeded. When assessing first-time revisions, this novel grading system has shown excellent intra- and interobserver reliability. Cite this article: Bone Joint J 2024;106-B(5):468–474

Aims. To identify variables independently associated with same-day discharge (SDD) of patients following revision total knee arthroplasty (rTKA) and to develop machine learning algorithms to predict suitable candidates for outpatient rTKA. Methods. Data were obtained from the American College of Surgeons National Quality Improvement Programme (ACS-NSQIP) database from the years 2018 to 2020. Patients with elective, unilateral rTKA procedures and a total hospital length of stay between zero and four days were included. Demographic, preoperative, and intraoperative variables were analyzed. A multivariable logistic regression (MLR) model and various machine learning techniques were compared using area under the curve (AUC), calibration, and decision curve analysis. Important and significant variables were identified from the models. Results. Of the 5,600 patients included in this study, 342 (6.1%) underwent SDD. The random forest (RF) model performed the best overall, with an internally validated AUC of 0.810. The ten crucial factors favoring SDD in the RF model include operating time, anaesthesia type, age, BMI, American Society of Anesthesiologists grade, race, history of diabetes, rTKA type, sex, and smoking status. Eight of these variables were also found to be significant in the MLR model. Conclusion. The RF model displayed excellent accuracy and identified clinically important variables for determining candidates for SDD following rTKA. Machine learning techniques such as RF will allow clinicians to accurately risk-stratify their patients preoperatively, in order to optimize resources and improve patient outcomes. Cite this article: Bone Jt Open 2023;4(6):399–407

Aims. Metal allergy in knee arthroplasty patients is a controversial topic. We aimed to conduct a scoping review to clarify the management of metal allergy in primary and revision total knee arthroplasty (TKA). Methods. Studies were identified by searching electronic databases: Cochrane Central Register of Controlled Trials, Ovid MEDLINE, and Embase, from their inception to November 2020, for studies evaluating TKA patients with metal hypersensitivity/allergy. All studies reporting on diagnosing or managing metal hypersensitivity in TKA were included. Data were extracted and summarized based on study design, study population, interventions and outcomes. A practical guide is then formulated based on the available evidence. Results. We included 38 heterogeneous studies (two randomized controlled trials, six comparative studies, 19 case series, and 11 case reports). The evidence indicates that metal hypersensitivity is a rare complication with some histopathological features leading to pain and dissatisfaction with no reliable screening tests preoperatively. Hypoallergenic implants are viable alternatives for patients with self-reported/confirmed metal hypersensitivity if declared preoperatively; however, concerns remain over their long-term outcomes with ceramic implants outperforming titanium nitride-coated implants and informed consent is paramount. For patients presenting with painful TKA, metal hypersensitivity is a diagnosis of exclusion where patch skin testing, lymphocyte transformation test, and synovial biopsies are useful adjuncts before revision surgery is undertaken to hypoallergenic implants with shared decision-making and informed consent. Conclusion. Using the limited available evidence in the literature, we provide a practical approach to metal hypersensitivity in TKA patients. Future national/registry-based studies are needed to identify the scale of metal hypersensitivity, agreed diagnostic criteria, and management strategies. Cite this article: Bone Jt Open 2021;2(10):785–795

Aims. The aim of this study was to perform a systematic review and bias evaluation of the current literature to create an overview of risk factors for re-revision following revision total knee arthroplasty (rTKA). Methods. A systematic search of MEDLINE and Embase was completed in accordance with the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines. The studies were required to include a population of index rTKAs. Primary or secondary outcomes had to be re-revision. The association between preoperative factors and the effect on the risk for re-revision was also required to be reported by the studies. Results. The search yielded 4,847 studies, of which 15 were included. A majority of the studies were retrospective cohorts or registry studies. In total, 26 significant risk factors for re-revision were identified. Of these, the following risk factors were consistent across multiple studies: age at the time of index revision, male sex, index revision being partial revision, and index revision due to infection. Modifiable risk factors were opioid use, BMI > 40 kg/m. 2. , and anaemia. History of one-stage revision due to infection was associated with the highest risk of re-revision. Conclusion. Overall, 26 risk factors have been associated with an increased risk of re-revision following rTKA. However, various levels of methodological bias were found in the studies. Future studies should ensure valid comparisons by including patients with identical indications and using clear definitions for accurate assessments. Cite this article: Bone Jt Open 2024;5(8):644–651

Aims. The aim of this study was to evaluate medium- to long-term outcomes and complications of the Stanmore Modular Individualised Lower Extremity System (SMILES) rotating hinge implant in revision total knee arthroplasty (rTKA) at a tertiary unit. It is hypothesized that this fully cemented construct leads to satisfactory clinical outcomes. Methods. A retrospective consecutive study of all patients who underwent a rTKA using the fully cemented SMILES rotating hinge prosthesis between 2005 to 2018. Outcome measures included aseptic loosening, reoperations, revision for any cause, complications, and survivorship. Patients and implant survivorship data were identified through both prospectively collected local hospital electronic databases and linked data from the National Joint Registry/NHS Personal Demographic Service. Kaplan-Meier survival analysis was used at ten years. Results. Overall, 69 consecutive patients (69 knees) were included with a median age of 78 years (interquartile range 69 to 84), and there were 46 females (66.7%). Indications were septic revisions in 26 (37.7%), and aseptic aetiology in the remining 43 (62.3%). The mean follow-up was 9.7 years (4 to 18), and the overall complication was rate was 7.24%, all with patellofemoral complications. Failure rate with ‘any cause revision’ was 5.8%. There was one case of aseptic loosening of the femoral component. At ten years, 17/69 patients (24.63%) had died, and implant survivorship was 92.2%. Conclusion. In our experience, the SMILES rotating hinge prosthesis achieves satisfactory long-term outcomes with ten-year implant survivorship of 92.2% and a patellofemoral complication rate of 7.24%. Cite this article: Bone Jt Open 2023;4(10):776–781

Aims. Tranexamic acid (TXA) is proven to reduce blood loss following total knee arthroplasty (TKA), but there are limited data on the impact of similar dosing regimens in revision TKA. The purpose of this multicentre randomized clinical trial was to determine the optimal regimen to maximize the blood-sparing properties of TXA in revision TKA. Patients and Methods. From six-centres, 233 revision TKAs were randomized to one of four regimens: 1 g of intravenous (IV) TXA given prior to the skin incision, a double-dose regimen of 1 g IV TXA given both prior to skin incision and at time of wound closure, a combination of 1 g IV TXA given prior to skin incision and 1 g of intraoperative topical TXA, or three doses of 1950 mg oral TXA given two hours preoperatively, six hours postoperatively, and on the morning of postoperative day one. Randomization was performed based on the type of revision procedure to ensure equivalent distribution among groups. Power analysis determined that 40 patients per group were necessary to identify a 1 g/dl difference in the reduction of haemoglobin postoperatively between groups with an alpha of 0.05 and power of 0.80. Per-protocol analysis involved regression analysis and two one-sided t-tests for equivalence. Results. In total, one patient withdrew, five did not undergo surgery, 16 were screening failures, and 25 did not receive the assigned treatment, leaving 186 patients for analysis. There was no significant difference in haemoglobin reduction among treatments (2.8 g/dl for single-dose IV TXA, 2.6 g/dl for double-dose IV TXA, 2.6 g/dl for combined IV/topical TXA, 2.9 g/dl for oral TXA; p = 0.38). Similarly, calculated blood loss (p = 0.65) and transfusion rates (p = 0.95) were not significantly different between groups. Equivalence testing assuming a 1 g/dl difference in haemoglobin change as clinically relevant showed that all possible pairings were statistically equivalent. Conclusion. Despite the higher risk of blood loss in revision TKA, all TXA regimens tested had equivalent blood-sparing properties. Surgeons should consider using the lowest effective dose and least costly TXA regimen in revision TKA. Cite this article: Bone Joint J 2019;101-B(Supple 7):10–16

Aims. Metaphyseal cones with cemented stems are frequently used in revision total knee arthroplasty (TKA). However, if the diaphysis has been previously violated, the resultant sclerotic canal can impair cemented stem fixation, which is vital for bone ingrowth into the cone, and long-term fixation. We report the outcomes of our solution to this problem, in which impaction grafting and a cemented stem in the diaphysis is combined with an uncemented metaphyseal cone, for revision TKA in patients with severely compromised bone. Methods. A metaphyseal cone was combined with diaphyseal impaction grafting and cemented stems for 35 revision TKAs. There were two patients with follow-up of less than two years who were excluded, leaving 33 procedures in 32 patients in the study. The mean age of the patients at the time of revision TKA was 67 years (32 to 87); 20 (60%) were male. Patients had undergone a mean of four (1 to 13) previous knee arthroplasty procedures. The indications for revision were aseptic loosening (80%) and two-stage reimplantation for prosthetic joint infection (PJI; 20%). The mean follow-up was four years (2 to 11). Results. Survival free from revision of the cone/impaction grafting construct due to aseptic loosening was 100% at five years. Survival free from any revision of the construct and free from any reoperation were 92% and 73% at five years, respectively. A total of six patients (six TKAs, 17%) required a further revision, four for infection or wound issues, and two for periprosthetic fracture. Radiologically, one unrevised TKA had evidence of loosening which was asymptomatic. In all unrevised TKAs the impacted diaphyseal bone graft appeared to be incorporated radiologically. Conclusion. When presented with a sclerotic diaphysis and substantial metaphyseal bone loss, this technique combining diaphyseal impaction grafting with a metaphyseal cone provided near universal success in relation to implant fixation. Moreover, radiographs revealed incorporation of the bone graft and biological fixation of the cone. While long-term follow-up will be important, this technique provides an excellent option for the management of complex revision TKAs. Cite this article: Bone Joint J 2020;102-B(6 Supple A):116–122

Aims. To map literature on prognostic factors related to outcomes of revision total knee arthroplasty (rTKA), to identify extensively studied factors and to guide future research into what domains need further exploration. Methods. We performed a systematic literature search in MEDLINE, Embase, and Web of Science. The search string included multiple synonyms of the following keywords: "revision TKA", "outcome" and "prognostic factor". We searched for studies assessing the association between at least one prognostic factor and at least one outcome measure after rTKA surgery. Data on sample size, study design, prognostic factors, outcomes, and the direction of the association was extracted and included in an evidence map. Results. After screening of 5,660 articles, we included 166 studies reporting prognostic factors for outcomes after rTKA, with a median sample size of 319 patients (30 to 303,867). Overall, 50% of the studies reported prospectively collected data, and 61% of the studies were performed in a single centre. In some studies, multiple associations were reported; 180 different prognostic factors were reported in these studies. The three most frequently studied prognostic factors were reason for revision (213 times), sex (125 times), and BMI (117 times). Studies focusing on functional scores and patient-reported outcome measures as prognostic factor for the outcome after surgery were limited (n = 42). The studies reported 154 different outcomes. The most commonly reported outcomes after rTKA were: re-revision (155 times), readmission (88 times), and reinfection (85 times). Only five studies included costs as outcome. Conclusion. Outcomes and prognostic factors that are routinely registered as part of clinical practice (e.g. BMI, sex, complications) or in (inter)national registries are studied frequently. Studies on prognostic factors, such as functional and sociodemographic status, and outcomes as healthcare costs, cognitive and mental function, and psychosocial impact are scarce, while they have been shown to be important for patients with osteoarthritis. Cite this article: Bone Jt Open 2023;4(5):338–356

Aims. Metaphyseal fixation during revision total knee arthroplasty (TKA) is important, but potentially difficult when using historical designs of cone. Material and manufacturing innovations have improved the size and shape of the cones which are available, and simplified the required bone preparation. In a large series, we assessed the implant survivorship, radiological results, and clinical outcomes of new porous 3D-printed titanium metaphyseal cones featuring a reamer-based system. Methods. We reviewed 142 revision TKAs in 139 patients using 202 cones (134 tibial, 68 femoral) which were undertaken between 2015 and 2016. A total of 60 involved tibial and femoral cones. Most cones (149 of 202; 74%) were used for Type 2B or 3 bone loss. The mean age of the patients was 66 years (44 to 88), and 76 (55 %) were female. The mean body mass index (BMI) was 34 kg/m. 2. (18 to 60). The patients had a mean of 2.4 (1 to 8) previous operations on the knee, and 68 (48%) had a history of prosthetic infection. The mean follow-up was 2.4 years (2 to 3.6). Results. Survivorship free of cone revision for aseptic loosening was 100% and survivorship free of any cone revision was 98%. Survivorships free of any revision and any reoperation were 90% and 83%, respectively. Five cones were revised: three for infection, one for periprosthetic fracture, and one for aseptic tibial loosening. Radiologically, three unrevised femoral cones appeared loose in the presence of hinged implants, while the remaining cones appeared stable. All cases of cone loosening occurred in patients with Type 2B or 3 defects. The mean Knee Society score (KSS) improved significantly from 50 (0 to 94) preoperatively to 87 (72 to 94) (p < 0.001). Three intraoperative fractures with cone impaction (two femoral, one tibial) healed uneventfully. Conclusion. Novel 3D-printed titanium cones, with a reamer-based system, yielded excellent early survivorship and few complications in patients with severe bone loss undergoing difficult revision TKA. The diversity of cone options, relative ease of preparation, and outcomes rivalling those of previous designs of cone support their continued use. Cite this article: Bone Joint J 2020;102-B(6 Supple A):107–115

Introduction. Revision total knee arthroplasty (TKA) is becoming increasingly common in the United States as the population ages and larger numbers of primary TKA are performed in younger individuals. Cemented or uncemented tibial stems are frequently used in revision cases. Decreased clinical outcomes and patient satisfaction have been described for revision TKA. This study aims to determine if the presence of overall pain and tibial pain at the end of the stem differs between cemented and uncemented tibial stems in revision TKA. Methods. This was a retrospective cohort study comparing patients who underwent revision TKA utilizing cemented or uncemented tibial stems in a 15-year period at a single institution with at least two-year follow-up. Exclusion criteria included age under 18, isolated revisions of the femoral component or polyethylene exchanges, lack of preoperative or postoperative imaging, insufficient operative or implant records available for electronic chart review, revision procedures performed at outside facilities, patients who were deceased at the time of survey administration, refusal to participate in the study, and failure to return the mailed survey or respond to a telephone follow-up questionnaire. Radiographic analysis included calculation of the percentage of the tibial canal filled with the implant, as well as measurement of the diameter of the tibial stem. Radiographs were also reviewed for evidence of cavitary defects, pedestal formation, radiolucent lines, and periprosthetic fractures. Mailed surveys addressing overall pain, tibial pain, and satisfaction were analyzed using Fisher's exact test and the independent sample t-test. Logistic regression was used to adjust for age, gender, and preoperative bone loss. Results. A total of 110 patients were included (63 cemented and 47 uncemented stems). No statistically significant differences in stem length, operative side, or indications for revision were found. The uncemented group had a significantly higher percent canal fill (p < 0.0001). Tibial pain at the end of the stem was present in 25.3% of cemented stems and 25.5% of uncemented stems (p = 1.00). There was a trend towards more overall pain in the uncemented cohort, but this did not reach statistical significance. Only 74.6% of cemented patients and 78.7% of uncemented patients were satisfied following revision TKA (p = 0.66). Conclusion. The data supports our hypothesis that there are no differences in end-of-stem pain or overall pain between cemented and uncemented tibial stems in revision TKA. High rates of dissatisfaction were noted in both cohorts postoperatively, consistent with previous literature. Patient factors likely play a large role in the presence of postoperative pain. These factors should be further evaluated in future studies in an effort to reduce pain and improve patient satisfaction

Abstract. Introduction. Revision total knee arthroplasty (rTKA) in elderly patients (>85 years) is associated with increased mortality, hospital stay and a high rate (55%) of complications. The objective was to assess PROMs in elderly patients undergoing rTKA. Methods. A retrospective cohort study of consecutive patients undergoing rTKA at an arthroplasty centre from 2001–2022 were compared to a control group (aged 50–79y) matched for gender, diagnosis & surgery year. The commonest reasons for revision in elderly patients was aseptic loosening (53/100), infection (21/100) and fracture (7/100). One-year patient-reported outcome data was available for 64%. Results. 100 patients underwent rTKA with a mean age of 84 years (range 80–97 years, SD 3) compared to a matched control group of younger patients (mean age 69y). Preoperative function was poor, with a mean Oxford knee score (OKS) of 40/100 in elderly and 43/100 in younger patients (p=0.164). At one-year postop, mean OKS was comparable between elderly and young patients (81 and 84/100 respectively, p=0.289). The number of patients with severe pain at one year was also comparable (4% elderly and 7% young respectively, p=0.177). The improvement in OKS for elderly patients was sustained at three (82 95% CI 58–100, 14/100 known) and five years. Overall complication rate was 54%. 14% were dead at 1 year and 56% were dead at five-years. Conclusion. Elderly patients undergoing elective revision TKA show a mean improvement in Oxford knee score of +38 at one year. This is the same as younger patients and is sustained at three and five years

Revision total knee arthroplasty (TKA) procedures performed secondary to periprosthetic joint infection (PJI) are associated with significant morbidity and mortality. These poor outcomes may be further complicated by the development of postoperative infection requiring aggressive antibiotic treatment. However, this antibiotic overuse may suppress patients' native bacterial flora, leading to Clostridium difficile infection (CDI). With the increased demand for primary TKAs and expected rise in revision TKA due to PJI, it is important to identify factors contributing to CDI. Therefore, we aimed to study the: 1) incidence, 2) demographics, length of stay (LOS), and total costs, and 3) risk factors and mortality associated with CDI in revision TKA patients. The National Inpatient Sample database was queried for all individuals diagnosed with PJI and who underwent revision TKA between 2009 and 2013. Patients who developed CDI during their in-patient hospital stay were identified, yielding 83,806 patients (799 with CDI) with a mean age of 65 (S.D.=11.2). Logistic regression analysis was conducted to assess the association between hospital- and patient-specific characteristics and the development of CDI. During the study period, the overall incidence of CDI after revision TKA was 1%. These patients were significantly older (mean age 69.05 vs. 65.52 yrs), had greater LOS (median 11 vs. 5 days), had greater costs ($30,612.93 vs. 18,873.75), and had higher in-hospital mortality (3.6 vs. 0.5%, p < 0 .001 for all) compared to those without infection. Patients with CDI were more likely to be treated in urban, not-for-profit, medium or large bed-sized hospitals located in the Northeast or Midwest (p < 0 .05 for all). Patients with underlying depression (OR 4.267, p=0.007) or fluid/electrolyte disorders (OR 3.48, p=0.001) were more likely to develop infection. Although CDI is a rare event following revision TKA, it can have detrimental consequences. Our report demonstrates that CDI is associated with longer LOS, higher costs, and greater in-hospital mortality. With increased legislative pressure to lower healthcare expenditures, it is crucial to identify means of preventing costly complications

Objectives. Preservation of posterior condylar offset (PCO) has been shown to correlate with improved functional results after primary total knee arthroplasty (TKA). Whether this is also the case for revision TKA, remains unknown. The aim of this study was to assess the independent effect of PCO on early functional outcome after revision TKA. Methods. A total of 107 consecutive aseptic revision TKAs were performed by a single surgeon during an eight-year period. The mean age was 69.4 years (39 to 85) and there were 59 female patients and 48 male patients. The Oxford Knee Score (OKS) and Short-form (SF)-12 score were assessed pre-operatively and one year post-operatively. Patient satisfaction was also assessed at one year. Joint line and PCO were assessed radiographically at one year. Results. There was a significant improvement in the OKS (10.6 points, 95% confidence interval (CI) 8.8 to 12.3) and the SF-12 physical component score (5.9, 95% CI 4.1 to 7.8). PCO directly correlated with change in OKS (p < 0.001). Linear regression analysis confirmed the independent effect of PCO on the OKS (p < 0.001) and the SF-12 physical score (p = 0.02). The overall rate of satisfaction was 85% and on logistic regression analysis improvement in the OKS (p = 0.002) was a significant predictor of patient satisfaction, which is related to PCO; although this was not independently associated with satisfaction. Conclusion. Preservation of PCO should be a major consideration when undertaking revision TKA. The option of increasing PCO to balance the flexion gap while maintaining the joint line should be assessed intra-operatively. Cite this article: N. D. Clement, D. J. MacDonald, D. F. Hamilton, R. Burnett. Posterior condylar offset is an independent predictor of functional outcome after revision total knee arthroplasty. Bone Joint Res 2017;6:172–178. DOI: 10.1302/2046-3758.63.BJR-2015-0021.R1

Aims. Metaphyseal tritanium cones can be used to manage the tibial bone loss commonly encountered at revision total knee arthroplasty (rTKA). Tibial stems provide additional fixation and are generally used in combination with cones. The aim of this study was to examine the role of the stems in the overall stability of tibial implants when metaphyseal cones are used for rTKA. Methods. This computational study investigates whether stems are required to augment metaphyseal cones at rTKA. Three cemented stem scenarios (no stem, 50 mm stem, and 100 mm stem) were investigated with 10 mm-deep uncontained posterior and medial tibial defects using four loading scenarios designed to mimic activities of daily living. Results. Small micromotions (mean < 12 µm) were found to occur at the bone-implant interface for all loading cases with or without a stem. Stem inclusion was associated with lower micromotion, however these reductions were too small to have any clinical significance. Peak interface micromotion, even when the cone is used without a stem, was too small to effect osseointegration. The maximum difference occurred with stair descent loading. Stress concentrations in the bone occurred around the inferior aspect of each implant, with the largest occurring at the end of the long stem; these may lead to end-of-stem pain. Stem use is also found to result in stress shielding in the bone along the stem. Conclusion. When a metaphyseal cone is used at rTKA to manage uncontained posterior or medial defects of up to 10 mm depth, stem use may not be necessary. Cite this article:Bone Joint Res. 2020;9(4):162–172

Aims. Both the femoral and tibial component are usually cemented at revision total knee arthroplasty (rTKA), while stems can be added with either cemented or press-fit (hybrid) fixation. The aim of this study was to compare the long-term stability of rTKA with cemented and press-fitted stems, using radiostereometric analysis (RSA). Methods. This is a follow-up of a randomized controlled trial, initially involving 32 patients, of whom 19 (nine cemented, ten hybrid) were available for follow-up ten years postoperatively, when further RSA measurements were made. Micromotion of the femoral and tibial components was assessed using model-based RSA software (RSAcore). The clinical outcome was evaluated using the Knee Society Score (KSS), the Knee injury and Osteoarthritis Outcome Score (KOOS), and visual analogue scale (pain and satisfaction). Results. The median total femoral translation and rotation at ten years were 0.39 mm (interquartile range (IQR) 0.20 to 0.54) and 0.59° (IQR 0.46° to 0.73°) for the cemented group and 0.70 mm (IQR 0.15 to 0.77) and 0.78° (IQR 0.47° to 1.43°) for the hybrid group. For the tibial components this was 0.38 mm (IQR 0.33 to 0.85) and 0.98° (IQR 0.38° to 1.34°) for the cemented group and 0.42 mm (IQR 0.30 to 0.52) and 0.72° (IQR 0.62° to 0.82°) for the hybrid group. None of these values were significantly different between the two groups and there were no significant differences between the clinical scores in the two groups at this time. There was only one re-revision, in the hybrid group, for infection and not for aseptic loosening. Conclusion. These results show good long-term fixation with no difference in micromotion and clinical outcome between fully cemented and hybrid fixation in rTKA, which builds on earlier short- to mid-term results. The patients all had type I or II osseous defects, which may in part explain the good results. Cite this article: Bone Joint J 2022;104-B(7):875–883

Aims. The aim of this study was to measure the effect of hospital case volume on the survival of revision total knee arthroplasty (RTKA). Methods. This is a retrospective analysis of Scottish Arthroplasty Project data, a nationwide audit which prospectively collects data on all arthroplasty procedures performed in Scotland. The primary outcome was RTKA survival at ten years. The primary explanatory variable was the effect of hospital case volume per year on RTKA survival. Kaplan-Meier survival curves were plotted with 95% confidence intervals (CIs) to determine the lifespan of RTKA. Multivariate Cox proportional hazards were used to estimate relative revision risks over time. Hazard ratios (HRs) were reported with 95% CI, and p-value < 0.05 was considered statistically significant. Results. From 1998 to 2019, 8,301 patients (8,894 knees) underwent RTKA surgery in Scotland (median age at RTKA 70 years (interquartile range (IQR) 63 to 76); median follow-up 6.2 years (IQR 3.0 to 10.2). In all, 4,764 (53.6%) were female, and 781 (8.8%) were treated for infection. Of these 8,894 knees, 957 (10.8%) underwent a second revision procedure. Male sex, younger age at index revision, and positive infection status were associated with need for re-revision. The ten-year survival estimate for RTKA was 87.3% (95% CI 86.5 to 88.1). Adjusting for sex, age, surgeon volume, and indication for revision, high hospital case volume was significantly associated with lower risk of re-revision (HR 0.78 (95% CI 0.64 to 0.94, p < 0.001)). The risk of re-revision steadily declined in centres performing > 20 cases per year; risk reduction was 16% with > 20 cases; 22% with > 30 cases; and 28% with > 40 cases. The lowest level of risk was associated with the highest volume centres. Conclusion. The majority of RTKA in Scotland survive up to ten years. Increasing yearly hospital case volume above 20 cases is independently associated with a significant risk reduction of re-revision. Development of high-volume tertiary centres may lead to an improvement in the overall survival of RTKA. Cite this article: Bone Joint J 2021;103-B(4):602–609

Aims. Single-stage revision total knee arthroplasty (rTKA) is gaining popularity in treating chronic periprosthetic joint infections (PJIs). We have introduced this approach to our clinical practice and sought to evaluate rates of reinfection and re-revision, along with predictors of failure of both single- and two-stage rTKA for chronic PJI. Methods. A retrospective comparative cohort study of all rTKAs for chronic PJI between 1 April 2003 and 31 December 2018 was undertaken using prospective databases. Patients with acute infections were excluded; rTKAs were classified as single-stage, stage 1, or stage 2 of two-stage revision. The primary outcome measure was failure to eradicate or recurrent infection. Variables evaluated for failure by regression analysis included age, BMI, American Society of Anesthesiologists grade, infecting organisms, and the presence of a sinus. Patient survivorship was also compared between the groups. Results. A total of 292 consecutive first-time rTKAs for chronic PJI were included: 82 single-stage (28.1%); and 210 two-stage (71.9%) revisions. The mean age was 71 years (27 to 90), with 165 females (57.4%), and a mean BMI of 30.9 kg/m. 2. (20 to 53). Significantly more patients with a known infecting organism were in the single-stage group (93.9% vs 80.47%; p = 0.004). The infecting organism was identified preoperatively in 246 cases (84.2%). At a mean follow-up of 6.3 years (2.0 to 17.6), the failure rate was 6.1% in the single-stage, and 12% in the two-stage groups. All failures occurred within four years of treatment. The presence of a sinus was an independent risk factor for failure (odds ratio (OR) 4.97; 95% confidence interval (CI) 1.593 to 15.505; p = 0.006), as well as age > 80 years (OR 5.962; 95% CI 1.156 to 30.73; p = 0.033). The ten-year patient survivorship rate was 72% in the single-stage group compared with 70.5% in the two-stage group. This difference was not significant (p = 0.517). Conclusion. Single-stage rTKA is an effective strategy with a high success rate comparable to two-stage approach in appropriately selected patients. Cite this article: Bone Joint J 2021;103-B(8):1373–1379

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. Revision total knee arthroplasty (rTKA) is a complex procedure with increased risk of blood loss and transfusions. The Musculoskeletal Infection Society has included D-dimer as a serology marker for peri-prosthetic infection. The study's intent is to understand the impact of preoperative D-dimer levels on blood loss and venous thromboembolism in revision TKA. Methods. Following IRB approval, rTKA performed by a single surgeon between January 1, 2017 and December 31, 2019 were reviewed. Inclusion criteria consisted of pre-operative D-Dimer, cemented revision TKA of one or both components under tourniquet control. 89 patients met the criteria including 37 males (41.6%) and 52 females (58.4%). Mean ages were 65 for males and 67 for females. The data revealed 54 patients (61%) had an elevated D-dimer (group 1) and 35 patients (39%) had a normal D-dimer (group 2). Sex stratification showed 21 males (57.8%) and 33 females (63.5%) with elevated D-dimer. TXA protocol included 2 grams intravenous (82 patients) or 2 grams intra-articular application (7 patients). Post-operative anticoagulation included Lovenox 40mg daily for 2 weeks followed by aspirin 325 twice daily for 4 weeks. Pre-operative and post-operative hemoglobin, transfusion rates and post-operative VTE within 90 days of surgery were recorded. Results. The mean pre-operative hemoglobin (hgb) was 13.30 and post-operative was 11.21. The mean change in hgb for males was 2.75 and for females 1.91. Both male and female cohorts had an acceptable range and the change in hgb was not statistically significant (p=0.076). Two female patients (2.25%) were transfused, both receiving IV TXA and their pre-operative hgb was lower than the cohort. No VTE events were identified in either groups of patients within the 90 day post-operative period. Conclusion. This study revealed that TXA is effective in reducing blood loss following rTKA and an elevated D-dimer is not a contraindication to its use

Aim. To improve the challenging treatment of periprosthetic joint infections (PJI), researchers are constantly developing new handling methods and strategies. In patients with PJI after total knee arthroplasty (TKA) and severe local or systemic comorbidities, a two-stage exchange using a temporary antibiotic loaded PMMA-spacer is considered gold standard. This method has undisputed advantages, however, the increased risk of biofilm formation on the spacer surface, bone defects and soft tissue contractions after a six-week spacer interval are severe limitations. Our hypothesis is that a vacuum sealed foam in combination with constant instillation of an antiseptic fluid can address these drawbacks due to a significantly reduced spacer interval. Method. A pilot study was conducted in five PJI cases after TKA with severe comorbidities and/or multiple previous operations to evaluate the feasibility and safety of the proposed method. In the first step, surgical treatment included the explantation of the prosthesis, debridement, and the implantation of the VeraFlo-Dressing foam. The foam is connected to the VAC-Instill-Device via an inflow and an outflow tube. The surgical site is sealed airtight with the VAC-film. During the next 5 days, an antiseptic fluid (Lavasorb® or Taurolidine®) is instilled in a 30-minute interval using the VAC-Instill-Device. The limb is immobilized (no flexion in the knee joint, no weight bearing) for five days. Following that, the second operation is performed in which the VAC-VeraFlo. TM. -Therapy System is explanted and the revision TKA is implanted after debridement of the joint. Results. No serious adverse event occurred during the VAC-Instill spacer treatment. The TKA revision was performed after a mean of 5.4 ± 1.9 days. Mean patient age was 71±6 years with a mean of 6 previous PJI surgeries. Host classification according to McPherson was I/B/3, III/B/3 and III/C/3 in three cases. Out of the five cases included, four were successfully treated and remained infect free to date (mean 14.2 ± 12 months; germs: methicillin-resistant s. aureus, e. coli, staph. lugdunensis and one culture neg.). One case with candida infection of a total femur prosthesis had to be treated with an enucleation of the hip due to rising inflammation parameters and signs of sepsis 7 days after VAC-Instill implantation. Conclusions. The presented data on the VAC-Instill spacer method in septic two-stage revision TKA show promising results regarding feasibility and safety. A prospective randomized controlled examination is in progress to evaluate the possible advantages over a two-stage approach using a standard PMMA spacer

Aims. The aim of this study was to evaluate medium-term outcomes and complications of the S-ROM NOILES Rotating Hinge Knee System (DePuy, USA) in revision total knee arthroplasty (rTKA) at a tertiary unit. Methods. A retrospective consecutive study of all patients who underwent a rTKA using this implant from January 2005 to December 2018. Outcome measures included reoperations, revision for any cause, complications, and survivorship. Patients and implant survivorship data were identified through both local hospital electronic databases and linked data from the National Joint Registry/NHS Personal Demographic Service. Kaplan-Meier survival analysis was used at ten years. Results. A total of 89 consecutive patients (89 knees) were included with 47 females (52.8%) and a median age of 74 years (interquartile range 66 to 79). The main indications were aseptic loosening with instability (39.4%; n = 35) and infection (37.1%; n = 33) with the majority of patients managed through two-stage approach. The mean follow-up was 7.4 years (2 to 16). The overall rate of reoperation, for any cause, was 10.1% (n = 9) with a rate of implant revision of 6.7% (n = 6). Only two cases required surgery for patellofemoral complications. Kaplan-Meier implant-survivorship analysis was 93.3% at ten years, using revision for any cause as an endpoint. Conclusion. This implant achieved high ten-year survivorship with a low complication rate, particularly patellofemoral complications. These can be avoided by ensuring central patella tracking and appropriate tension of the patellofemoral joint in this posterior hinge design. Cite this article: Bone Jt Open 2022;3(3):205–210

Aims. It has previously been shown that higher-volume hospitals have better outcomes following revision total knee arthroplasty (rTKA). We were unable to identify any studies which investigated the effect of surgeon volume on the outcome of rTKA. We sought to investigate whether patients of high-volume (HV) rTKA surgeons have better outcomes following this procedure compared with those of low-volume (LV) surgeons. Methods. This retrospective study involved patients who underwent aseptic unilateral rTKA between January 2016 and March 2019, using the database of a large urban academic medical centre. Surgeons who performed ≥ 19 aseptic rTKAs per year during the study period were considered HV and those who performed < 19 per year were considered LV. Demographic characteristics, surgical factors, and postoperative outcomes were compared between the two groups. Results. A total of 308 rTKAs were identified, 132 performed by HV surgeons and 176 by 22 LV surgeons. The LV group had a significantly greater proportion of non-smokers (59.8% vs 49.2%; p = 0.029). For all types of revision, HV surgeons had significantly shorter mean operating times by 17.75 minutes (p = 0.007). For the 169 full revisions (85 HV, 84 LV), HV surgeons had significantly shorter operating times (131.12 (SD 33.78) vs 171.65 (SD 49.88) minutes; p < 0.001), significantly lower re-revision rates (7.1% vs 19.0%; p = 0.023) and significantly fewer re-revisions (0.07 (SD 0.26) vs 0.29 (SD 0.74); p = 0.017). Conclusion. Patients of HV rTKA surgeons have better outcomes following full rTKA. These findings support the development of revision teams within arthroplasty centres of excellence to offer patients the best possible outcomes following rTKA. Cite this article: Bone Joint J 2021;103-B(6 Supple A):131–136

Aims. Current guidelines consider analyses of joint aspirates, including leucocyte cell count (LC) and polymorphonuclear percentage (PMN%) as a diagnostic mainstay of periprosthetic joint infection (PJI). It is unclear if these parameters are subject to a certain degree of variability over time. Therefore, the aim of this study was to evaluate the variation of LC and PMN% in patients with aseptic revision total knee arthroplasty (TKA). Methods. We conducted a prospective, double-centre study of 40 patients with 40 knee joints. Patients underwent joint aspiration at two different time points with a maximum period of 120 days in between these interventions and without any events such as other joint aspirations or surgeries. The main indications for TKA revision surgery were aseptic implant loosening (n = 24) and joint instability (n = 11). Results. Overall, 80 synovial fluid samples of 40 patients were analyzed. The average time period between the joint aspirations was 50 days (SD 32). There was a significantly higher percentage change in LC when compared to PMN% (44.1% (SD 28.6%) vs 27.3% (SD 23.7%); p = 0.003). When applying standard definition criteria, LC counts were found to skip back and forth between the two time points with exceeding the thresholds in up to 20% of cases, which was significantly more compared to PMN% for the European Bone and Joint Infection Society (EBJIS) criteria (p = 0.001), as well as for Musculoskeletal Infection Society (MSIS) (p = 0.029). Conclusion. LC and PMN% are subject to considerable variation. According to its higher interindividual variance, LC evaluation might contribute to false-positive or false-negative results in PJI assessment. Single LC testing prior to TKA revision surgery seems to be insufficient to exclude PJI. On the basis of the obtained results, PMN% analyses overrule LC measurements with regard to a conclusive diagnostic algorithm. Cite this article: Bone Jt Open 2021;2(8):566–572

Aims. Porous metaphyseal cones can be used for fixation in revision total knee arthroplasty (rTKA) and complex TKAs. This metaphyseal fixation has led to some surgeons using shorter cemented stems instead of diaphyseal engaging cementless stems with a potential benefit of ease of obtaining proper alignment without being beholden to the diaphysis. The purpose of this study was to evaluate short term clinical and radiographic outcomes of a series of TKA cases performed using 3D-printed metaphyseal cones. Methods. A retrospective review of 86 rTKAs and nine complex primary TKAs, with an average age of 63.2 years (SD 8.2) and BMI of 34.0 kg/m. 2. (SD 8.7), in which metaphyseal cones were used for both femoral and tibial fixation were compared for their knee alignment based on the type of stem used. Overall, 22 knees had cementless stems on both sides, 52 had cemented stems on both sides, and 15 had mixed stems. Postoperative long-standing radiographs were evaluated for coronal and sagittal plane alignment. Adjusted logistic regression models were run to assess malalignment hip-knee-ankle (HKA) alignment beyond ± 3° and sagittal alignment of the tibial and femoral components ± 3° by stem type. Results. No patients had a revision of a cone due to aseptic loosening; however, two had revision surgery due to infection. In all, 26 (27%) patients had HKA malalignment; nine (9.5%) patients had sagittal plane malalignment, five (5.6%) of the tibia, and four (10.8%) of the femur. After adjusting for age, sex, and BMI, there was a significantly increased risk for malalignment when a cone was used and both the femur and tibia had cementless compared to cemented stems (odds ratio 3.19, 95% confidence interval 1.01 to 10.05). Conclusion. Porous 3D-printed cones provide excellent metaphyseal fixation. However, these central cones make the use of offset couplers difficult and may generate malalignment with cementless stems. We found 3.19-times higher odds of malalignment in our TKAs performed with metaphyseal cones and both femoral and tibial cementless stems. Cite this article: Bone Joint J 2021;103-B(6 Supple A):150–157

Background. Joint line, patellar height and posterior condylar offset (PCO) are related to functional outcome such as stability and range of motion after revision total knee arthroplasty (TKA). The purpose of this study was (1) to determine whether revision TKA can restore the joint line, patella height and condylar offset after surgery, and (2) to assess factors associated with failed restoration. Materials and Methods. We retrospectively reviewed 27 consecutive patients who underwent revision TKA. Among 27 patients, 11 patients had two-stage revision TKA due to periprosthetic joint infection while 14 patients underwent revision TKA due to aseptic loosening. In addition, there were 2 patients who had traumatic event causing a periprosthetic fracture which led to revision TKA. The joint line was measured using the distance from the adductor tubercle of the femur to the most distal portion of the medial femoral component on knee anterior-posterior radiographs. Patella height was assessed using the Caton-Deschamps method. In addition, PCO were measured relative to the tangent of the posterior cortex of the femur using knee lateral radiograph. All parameters were compared between pre- and postoperative radiographs after revision TKA. Results. After revision TKA, mean joint line elevation was 0.9 mm. Seven of 27 patients showed joint line elevation of 5 mm or more. There was no significant difference between pre- and postoperative PCO (27.6 mm and 28.1 mm, respectively; P = 0.528). Fifteen patients (56%) showed patellar baja after revision TKA. Compared to the patients with aseptic loosening, the patients with periprosthetic joint infection or fracture showed greater joint line elevation (4.1 mm and −2.2 mm, respectively; P < 0.01), smaller PCO change (1.9 mm and −1.1 mm respectively, P < 0.05). Even if the cause of revision TKA was not associated with the postoperative patellar baja, presence of preoperative patellar baja was significantly associated with postoperative patellar baja (P < 0.05). Conclusions. Overall, restoration of the joint line and PCO were achieved in contemporary revision TKA. However, the patients who underwent revision TKA due to periprosthetic joint infection or fracture showed greater joint line elevation as well as smaller PCO. In addition, the patellar height was not improved in patients with preoperative patellar baja. Further evaluation of functional outcome is needed to assess correlation between radiological and functional outcome

Little information exists regarding optimal tibial stem usage in revision total knee arthroplasty (rTKA) utilising a tibial trabecular metal (TM) cone. The purpose of this study was to compare 1) functional outcomes, 2) radiographic outcomes, and 3) implant survivorship in rTKA utilising TM cones combined with either short stems (SS) or long stems (LS) at minimum two-years clinical follow-up. In this retrospective, multi-centre study, patients undergoing TM cone utilising rTKA between 2008 and 2019 were included. Patients were divided into: SS group (no diaphyseal engagement), and LS group (diaphyseal engagement). All relevant clinical charts and post-operative radiographs were examined. Oxford Knee Score (OKS) and EuroQol-5D (EQ-5D-5L) data were collected at most recent follow-up. In total, 44 patients were included: 18 in the SS group and 26 in the LS group. The mean time of follow-up was 4.0 years. Failure free survival was 94.5% for the SS group and 92.3% for the LS group. All failures were for prosthetic joint infections managed with debridement, antibiotics, and implant retention. At most recent follow-up, 3 patients demonstrated radiographic signs of lucency (1 SS 2 LS, p = 1) and the mean OKS were 37 ± 4 and 36 ± 6 (p = 0.73) in the SS and LS groups, respectively. Tibial SS combined with TM cones performed as well as LS in rTKA at minimum two-years follow-up. A tibial SS in combination with a TM cone is a reliable technique to achieve stable and durable fixation in rTKA

Background. Patellar dislocation is a serious complication leading to patient morbidity following total knee arthroplasty. The cause can be multifactorial. Extensor mechanism imbalance may be present and result from technical errors such as malrotation of the implants. Methods. We performed a retrospective study assessing the outcomes of revision surgery for patellar dislocation in patients with component malrotation in both primary and revision total knee arthroplasty. Patient demographics, etiology of dislocation, presurgical deformity, intraoperation component position, complications, reoperation and knee society scores were collected. Results. Twenty patients (twenty-one knees) were identified. The average time from primary arthroplasty to onset of dislocation was 33.6 months (SD, 44.4), and the average time from dislocation to revision was 3.38 months (SD, 2.81). Seventeen knees (80.1%) had internal rotation of the tibial component and 7 knees (33.3%) had combined internal rotation of both the femoral and tibial components. Sixteen knees (76.1%) were treated with a condylar constrained implant at the time of revision, and 5 knees were converted to a hinged prosthesis. The average follow-up time was 56 months. During this time, one patient (4.54%) had a recurrent dislocation episode, requiring further surgery. At final follow up, the mean knee society score for the patient cohort was 86.2. Conclusion. Revision total knee arthroplasty to treat patellar dislocation in patients with malrotated components was associated with high success rates. After revision surgery, patients had a low recurrence of patellar dislocation, low complication rates, and excellent functional outcomes. For figures, tables, or references, please contact authors directly

Abstract. Objectives. 1. To investigate the effect of revision total knee replacement (TKR) on gait kinematics in patients with a primary TKR and instability.2. To compare gait kinematics between patients with a well-functioning TKR and those with a primary TKR and symptoms of instability. Methods. This single-centre observational study is following patients who have had a revision TKR due to knee instability. Data was collected pre- and post-operatively at 8–12 week follow-up. The data was compared to a control group of 18 well-functioning TKR patients. Kinematic gait data was collected during routine clinics using a treadmill-based infrared 3D system (Vicon, Oxford, UK) and a published lower limb marker-set. Patients performed 15 strides at three different speeds: 0.6mph, self-selected, and a ‘slow walk’ normalised to leg length (Froude number 0.09). PROMs questionnaires were collected. NHS ethical approval was obtained. Results. Data was collected for 18 well-functioning TKR patients and 8 revision TKR patients pre- and post-operatively, but only 5 could walk at the normalised speed. When walking at a normalised speed (Froude 0.09), patients with a TKR with instability had reduced range of knee flexion (52° (sd 14)) compared to those with a well-functioning TKR (59° (sd 11)). Short term follow-up after a revision TKR operation demonstrated a stiffer knee (45° (sd 12)). However, those with revision TKR had a more flexed knee during stance phase. Conclusions. At short-term follow-up, this cohort of revision TKR patients appear to have reduced flexion range, while remaining more flexed during stance. This may represent a less efficient gait pattern, which may also adversely affect the implant[1]. Longer term follow-up may demonstrate whether this normalises with post-operative rehabilitation. Declaration of Interest. (b) declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported:I declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project

The amount of bone loss due to implant failure, loosening, or osteolysis can vary greatly and can have a major impact on reconstructive options during revision total knee arthroplasty (TKA). Massive bone loss can threaten ligamentous attachments in the vicinity of the knee and may require use of components with additional constraint to compensate for associated ligamentous instability. Classification of bone defects can be helpful in predicting the complexity of the reconstruction required and in facilitating preoperative planning and implant selection. One very helpful classification of bone loss associated with TKA is the Anderson Orthopaedic Research Institute (AORI) Bone Defect Classification System as it provides the means to compare the location and extent of femoral and tibial bone loss encountered during revision surgery. In general, the higher grade defects (Type IIb or III) on both the femoral and tibial sides are more likely to require stemmed components, and may require the use of either structural graft or large augments to restore support for currently available modular revision components. Custom prostheses were previously utilised for massive defects of this sort, but more recently have been supplanted by revision TKA component systems with or without special metal augments or structural allograft. Options for bone defect management are: 1) Fill with cement; 2) Fill with cement supplemented by screws or K-wires; 3) Morselised bone grafting (for smaller, especially contained cavitary defects); 4) Small segment structural bone graft; 5) Impaction grafting; 6) Porous metal cones or sleeves 7) Massive structural allograft-prosthetic composites; 8) Custom implants. Of these, use of uncemented highly porous metal metaphyseal cones in combination with an initial cemented or partially cemented implant has been shown to provide versatile and highly durable results for a range of bone defects including those previously requiring structural bone graft. The hybrid fixation combination of both cement and cementless fixation of an individual tibial or femoral component has emerged as a frequent and often preferred technique. Initial secure and motionless interfaces are provided by the cemented portions of the construct, while subsequent bone ingrowth to the cementless porous metal portions is the key to long term stable fixation. As bone grows into the porous portions there is off loading and protection of the cemented interfaces from mechanical stresses. While maximizing support on intact host bone has been a longstanding fundamental principle of revision arthroplasty, this is facilitated by the use of metaphyseal cones or sleeves in combination with initial fixation into the adjacent diaphysis. Preoperative planning is facilitated by good quality radiographs, supplemented on occasion by additional imaging such as CT. Fluoroscopically controlled x-ray views may assist in diagnosing the loose implant by better revealing the interface between the implant and bone and can facilitate accurate delineation of the extent of bone deficiency present. Part of the preoperative plan is to ensure adequate range and variety of implant choices and bone graft resources for the planned reconstruction allowing for the potential for unexpected intraoperative findings such as occult fracture through deficient periprosthetic bone. While massive bone loss may compromise ligamentous attachment to bone, in the majority of reconstructions, the degree of revision implant constraint needed for proper balancing and restoration of stability is independent of the bone defect. Thus, some knees with minimal bone deficiency may require increased constraint due to the status of the soft tissues while others involving very large bone defects, especially of the cavitary sort, may be well managed with minimal constraint

Over the last decade, the number of total knee arthroplasty (TKA) has risen over 125%. Numerous studies have established a relationship between obesity and complications in primary TKA. Interestingly, few studies have investigated medical and orthopaedic complications in obese patients undergoing revision TKA (RTKA). With the increasing number of RTKA and with the prevalence of obesity still on the rise, the study of obesity on complications following RTKA is indicated. We retrospectively reviewed 180 RTKA performed by a single surgeon done between August 2008 and June 2017. All patients who underwent RTKA were included, but revisions done with simultaneous extensor mechanism reconstruction and/or distal femur replacement were excluded since these procedures are technically more demanding. 154 revisions met our inclusion/exclusion criteriaes and were included in the final analysis. 81 patients were included in the non-obese group (BMI . The total number of orthopaedic complications in the obese group (46.6%) was significantly higher than in the non-obese group (27.2%) (OR=1.71) (p = 0.01). The number of infection was higher in the obese group (11%) than in the non-obese (6.2%) but this was not statistically significant (OR=1.77) (p = 0.28). Reoperation rate was also higher in the obese group (23.3%) than in the non-obese group (16%) but this did not reach statistical significance (OR=1.46) (p = 0.26) (Table 3). Medical complications were higher in the obese group (31.5% vs 19.8%) (OR=1.59) (p=0.09). According to the Dindo-Clavien classification, the obese group demonstrated a significantly higher rate of grade 3 or higher complications (p = 0.01). Obesity significantly increases the occurrence of orthopaedic complications following RTKA. Obesity also seems to increase the number of medical complications following RTKA. The obese patient should be informed prior to revision TKA that there is an increased risk of complications when compared with the non-obese patient. Further research with higher power would seem advisable to confirm this trend. For any figures or tables, please contact the authors directly

Introduction. Tranexamic acid (TXA) is proven to reduce blood loss following total knee arthroplasty (TKA), but there are limited data on the impact of similar dosing regimens in revision TKA that is associated with greater blood loss. The purpose of this multi-center randomized trial was to determine the optimal regimen to maximize the blood-sparing properties of TXA in revision TKA. Methods. 233 Septic and aseptic revision TKA from six-centers were randomized to either receive 1g pre-incision intravenous (IV) TXA, 1g pre- and post-incision IV TXA, 1g pre-incision IV and 1g intra-operative topical TXA, or three doses of 1950mg oral TXA given 2 hours pre-operatively, 6 hours post-operatively, and the morning of postoperative day 1. Randomization was performed based on type of revision to ensure equivalent distribution among groups. The primary outcome was reduction in hemoglobin. Power analysis determined 40 patients per group were necessary to identify a 1g/dL difference with an alpha of 0.05 and beta of 0.80. Per-protocol analysis involved regression analysis and two one-sided t-tests for equivalence. Results. One patient withdrew, 3 didn't undergo surgery, 16 were screen failures, and 17 did not receive the assigned treatment, leaving 196 patients for the analysis. There was no significant difference in reduction in hemoglobin amongst treatment groups (2.88g/dL for oral TXA, 2.79g/dL for single-dose IV TXA, 2.59g/dL for combined IV/topical TXA, and 2.58g/dL for double-dose IV TXA; p=0.48). Similarly, calculated blood loss (p=0.63) and transfusions (p=0.78) were not significantly different between groups. Finally, equivalence testing assuming a 1g/dL difference in hemoglobin change as clinically relevant showed all possible pairings were statistically equivalent. Conclusions. Despite the higher risk of blood loss in revision TKA, all TXA regimens tested had equivalent blood-sparing properties. Surgeons should consider using the lowest effective dose and the least costly regimen for TXA use in revision TKA

Purpose. The aim of this study was to compare the clinical outcomes of the revision TKA in which trabecular metal cones and femoral head allografts were used for large bone defect. Method. Total 53 patients who have undergone revision TKA from July 2013 to March 2017 were enrolled in this study. Among them, 24 patients used trabecular metal cones, and 29 patients used femoral head allografts for large bone defect. There were 3 males and 21 females in the metal cone group, while there were 4 males and 25 females in the allograft group. The mean age was 70.2 years (range, 51–80) in the femoral head allograft group, while it was 79.1 years (range, 73–85) in the metal cone group. Bone defect is classified according to the AORI classification and clinical outcomes were evaluated with Visual Analogue Scale (VAS), Hospital Special Surgery-score (HSS), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), Knee Injury and Osteoarthritis Outcome Score (KOOS), and ROM. Operation time was also evaluated. We used radiographs to check complications such as migration or loosening. We took follow-up x-rays and 3D CT of the patients, to assess the mean bone union period. Shapiro-Wilk test was done to check normality and Student T-test and Mann Whitney U-test were done for comparison between two groups. Result. The mean follow-up period was 3 .75 years (Range; 2.1 ∼ 5.75). The pre-op scores did not show significant difference. The mean VAS in the allograft and trabecular metal cone groups was 2.1 ± 0.87 and 1.8 ± 0.53, respectively (p = 0.16). The mean HSS score were 76.3 ± 5.51 and 79.2 ± 4.12 respectively (p = 0.13) and the mean WOMAC scores were 15.1 ± 3.25 and 14.8 ± 3.31 respectively (p = 0.06), and the mean KOOS scores were 27.8 ± 4.77 and 25.5 ± 4.84, respectively (p = 0.07). The mean ROM ranges were 100.6 ± 17.54 and 101.3 ± 19.22, respectively (p = 0.09). But the mean operation time of the allograft and trabecular metal cone groups was 137 minutes (Range; 111–198) and 102minutes (Range; 93 −133) (p=0.02) respectively, which showed statistical significance. In follow-up x-rays, no migration or loosening of the implants, osteolysis and other complications were found in both groups. In follow-up 3D CT, osteointegration was seen at the trabecular metal cone site, host bone being interpreted to the host bone. The allograft group showed fibrous and stable union in follow-up 3D CT. Conclusion. According to this study, in case of revision TKA with large bone defect, using whether allograft or trabecular metal cones did not affect the clinical outcomes. However, operation time was significantly shorter in trabecular metal cone group, therefore, in patients with poor general condition along with severe underlying diseases, usage of trabecular metal cone would be a better choice to shorten operation time and ease postoperative care. Keywords. Revision TKA, metal cone, allograft, bone defect. For any figures or tables, please contact authors directly

Purpose. The aim of this study was to assess the clinical and radiological result of the usage of chip bone graft in non-contained type bone defect in primary or revision total knee arthroplasty patients. Subjects and Methods. We investigated 32 patients who had underwent primary or revision total knee arthroplasty from March, 2014 to February, 2017 in our hospital, who had non-contained type of defect. The mean age was 73.1 years. 5 of them were males, while 27 of them were females. 7 of them were primary total knee arthroplasty patients, while 25 of them were revision patients. 8 of them had chip bone graft used both in the femur and tibia. 9 of them had chip bone graft used only in the tibia. The other 15 had chip bone graft used only in the femur. Wire-mesh was used in the 9 patients who had chip bone graft used only in the medial side of the tibia. We used KOOS (Knee injury and osteoarthritis outcome score), HSS (Hospital for Special Surgery knee service rating system) and WOMAC scores to assess the clinical result, before the surgery and at the last follow-up. In addition, we had follow-up x-rays and 3D CT done for the patients to check the mean bone union period. In addition, overall radiologic imaging studies were used for complications such as loosening, osteolysis and lesions with radiolucency. Result. The Mean follow-up period was 2.7 years (range; 2.1 to 5). The Mean preoperative KOOS was 102.8 (range; 47 to 132), while it became 31.8 postoperatively (range; 20 to 45). The mean HSS was 13.1 (range; 6 to 35), while it became 35.9 postoperatively (range; 24 to 64). The mean WOMAC was 82.9 (range; 62 to 92), while it became 22.5 postoperatively (range; 13 to 30). According to follow-up x-ray and CT, the mean bone union period was 10.6 months (range: 10 to 13). In follow-up 3D CT of all cases, we could check cortical healing and new bone formation, seen as medium to high-attenuating conglomerate. The graft-host junction showed trabecular ingrowth, while the medullary canal showed fibrous ingrowth. Radiologically, there was no complication such as loosening, osteolysis, migration and radiolucent lines around the stems or cement mantles. In addition, there was no complication such as infection. Conclusion. Chip bone graft is not a commonly used method for bone defect in total knee arthroplasty. According to the result of the usage of chip bone graft in primary or revision total knee arthroplasty with non-contained type of bone defect, it showed favorable result for the subject patients. Therefore, we can consider it as one of the effective methods to manage non-contained bone defect in knee arthroplasty. Keywords. Revision TKA, chip bone graft, wire-mesh, non-contained bone defect. For any figures or tables, please contact authors directly

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. Tibial cones are often utilized in revision total knee arthroplasty (TKA) with metaphyseal defects. However, there are few studies evaluating outcomes out to five years with a sufficient cohort. The purpose of this study was to evaluate implant survivorship and complications in revision TKAs with tibial cones. Methods. A retrospective review was completed from September 2006 through March 2018 evaluating 149 revision TKAs that received a tibial cone. The mean follow-up was 5.3 years. According to the AORI classification: 8% were 1, 18% were 2A, 55% were 2B, and 19% were 3. Results. Survival analysis at 6 years showed 96% free of revision for aseptic tibial loosening, 85% free of tibial component revision for any reason, and 72% free of reoperation. Eleven knees had progressive radiolucent lines with eight having tibial construct migration on serial radiographs. Aseptic tibial loosening was associated with significant tibial bone loss, AORI 3 (p=0.0001). Tibial component revision for any reason was associated with AORI 3 (p=0.013) and a pre-revision diagnosis of reimplantation after PJI (p<0.0001). Four knees had revision for aseptic tibial loosening, 12 knees had revision of the tibial construct for reasons other than aseptic loosening (11/12 were for PJI), and 15 knees had reoperation for reasons other than tibial construct revision. Conclusions. Revision TKA with tibial cones had excellent survivorship free of revision for tibial construct aseptic loosening, 96% at 6 years. Patients receiving a tibial cone construct at the time of reimplantation for PJI were at increased risk for tibial construct revision

Aims. Varus-valgus constrained (VVC) implants are often used during revision total knee arthroplasty (TKA) to gain coronal plane stability. However, the increased mechanical torque applied to the bone-cement interface theoretically increases the risk of aseptic loosening. We assessed mid-term survivorship, complications, and clinical outcomes of a fixed-bearing VVC device in revision TKAs. Methods. A total of 416 consecutive revision TKAs (398 patients) were performed at our institution using a single fixed-bearing VVC TKA from 2007 to 2015. Mean age was 64 years (33 to 88) with 50% male (199). Index revision TKA diagnoses were: instability (n = 122, 29%), aseptic loosening (n = 105, 25%), and prosthetic joint infection (PJI) (n = 97, 23%). All devices were cemented on the epiphyseal surfaces. Femoral stems were used in 97% (n = 402) of cases, tibial stems in 95% (n = 394) of cases; all were cemented. In total, 93% (n = 389) of cases required a stemmed femoral and tibial component. Femoral cones were used in 29%, and tibial cones in 40%. Survivorship was assessed via competing risk analysis; clinical outcomes were determined using Knee Society Scores (KSSs) and range of movement (ROM). Mean follow-up was four years (2 to 10). Results. The five-year cumulative incidence of subsequent revision for aseptic loosening and instability were 2% (95% confidence interval (CI) 0.2 to 3, number at risk = 154) and 4% (95% CI 2 to 6, number at risk = 153), respectively. The five-year cumulative incidence of any subsequent revision was 14% (95% CI 10 to 18, number at risk = 150). Reasons for subsequent revision included PJI (n = 23, of whom 12 had previous PJI), instability (n = 13), and aseptic loosening (n = 11). The use of this implant without stems was found to be a significant risk factor for subsequent revision (hazard ratio (HR) 7.58 (95% CI 3.98 to 16.03); p = 0.007). KSS improved from 46 preoperatively to 81 at latest follow-up (p < 0.001). ROM improved from 96° prerevision to 108° at latest follow-up (p = 0.016). Conclusion. The cumulative incidence of subsequent revision for aseptic loosening and instability was very low at five years with this fixed-bearing VVC implant in revision TKAs. Routine use of cemented and stemmed components with targeted use of metaphyseal cones likely contributed to this low rate of aseptic loosening. Cite this article: Bone Joint J 2020;102-B(4):458–462

Stems are a crucial part of implant stabilization in revision total knee arthroplasty. In most cases the metaphyseal bone is deficient, and stabilization in the diaphyseal cortical bone is necessary to keep the implant tightly fixed to bone and to prevent tilt and micromotion. While sleeves and cones can be effective in revision total joint arthroplasty, they are technically difficult and may lead to major bone loss in cases of loosening or infection, especially if the stem is cemented past the cone. A much more conservative method is to ream the diaphysis to the least depth possible to achieve tight circumferential fixation, and to apply porous augments to the undersurface of the tibial tray or inner surface of the femoral component to allow them to bottom out against the bone surface and apply compressive load. If a robust, strong taper, stem and component combination is used, rim contact on only one side is necessary to achieve rigid permanent fixation. Porous and non-porous stems are available. The non-porous stems should have a spline surface that engages the diaphyseal bone and achieves rigid initial fixation but does not provide long-term axillary support. In that way the porous rim-engaging surface can bear compressive load and finally unload the stem and taper junction. Correctly designed stems do not stress relieve unless they are porous-coated. In situations where metaphyseal bone is not available, porous-coated stems that link to hinge prostheses are a very important part of the armamentarium in complex revision arthroplasty. Use of stems requires experience and special technique. Slight underreaming and initial scratch fit are necessary techniques. This does not result in tight fixation every time because split of the cortex does occasionally occur. In most cases these splits do not need to be repaired, but when there is a question, an intra-operative x ray should be taken and the surgeon should be prepared to repair the fracture. Stems are an essential part of revision total knee arthroplasty. A tightly fit stem in the diaphysis is necessary for fixation when metaphyseal bone is deficient. No amount of cement pressed into the deficient metaphyseal bone will substitute for rigid stem fixation

Introduction. Revision total knee arthroplasty (revision TKA) occurs for a wide variety of indications and along with revision total hip arthroplasty is billed for using Diagnosis-Related Groups (DRGs) 466, 467, and 468 in the United States. However, DRGs do not account for revision etiology, a potentially substantial driver of cost. This study investigates revision TKA costs and 30-day complications by indication, employing both local granular as well as national standardized databases. Methods. Hospitalization costs and complication rates for 1,422 aseptic revision TKAs performed at a high-volume center between 2009 and 2015 were retrospectively reviewed. Additionally, charges for 28,173 revision TKAs in the National Inpatient Sample (NIS) were converted to costs using the Healthcare Cost and Utilization Project cost-to-charge ratios. 30-day complication rates for 3,450 revision TKAs were obtained using the American College of Surgeons National Surgical Quality Improvement Project (ACS-NSQIP). Costs and complications were compared between revision TKAs performed for the indication of fracture, wear/loosening, and instability with use of simultaneous and pairwise comparisons and a multivariable model accounting for American Society of Anesthesiologists (ASA) score, age, and sex. Results. Local hospitalization costs for fracture (median, $30,643) were significantly higher than those for wear/loosening ($24,734; p < 0.001) or instability ($22,932; p < 0.001), with differences remaining significant even after adjusting for patient comorbidities (p < 0.001). Local fracture patients were admitted for an average of 1.9 days longer (mean length of stay [LOS]: 4.8 days; IQR: 3 – 6) than instability patients (mean LOS: 2.9; IQR: 2 – 3; p < 0.001) and 1.7 days longer than wear/loosening patients (mean LOS: 3.1, IQR: 2 – 3; p < 0.001) but had similar 30-day orthopedic-specific complication rates (10.8%) as compared to instability (11.2%; p > 0.999) and wear/loosening (15.9%; p = 0.333). Nationally, NIS costs for fracture (median, $31,207) were higher than those for other aseptic indications (wear/loosening: $21,747; instability: $16,456; p< 0.001). Combined medical and surgical complication rates for fracture (56.6% of patients with ≥1 complication) were significantly higher than those for wear/loosening (19.7%) and instability (15.5%) (p < 0.001), with 3.5 – 5.4 fold increased transfusion rates (45.7% fracture, 13.2% wear/loosening, 8.5% instability; p < 0.001) and 1.2 – 3.3 fold increased urinary tract infection rates (2.3% fracture, 0.7% wear/loosening, 1.9% instability; p = 0.004). Discussion and Conclusion. Hospitalization costs for revision TKA for fracture were 37% to 50% higher than for all other aseptic revision TKAs, both locally and nationally. This increased cost persisted even after multivariable comorbidity adjustment, the current approach for DRG assignment for both revision TKA and THA reimbursement. Indication-specific coding and reimbursement systems are necessary to maintain sustainable access to revision TKA for all patients. For figures, tables, or references, please contact authors directly

We analyzed the causes of 113 revision total knee arthroplasties in 84 patients between December 1996 and June 2008. Patient history, medical record and radiographs were reviewed to detect the main cause of failure of primary total knee arthroplasty. The causes of revision total knee arthroplasty were as follows: 44 infections (38.9 %), 34 loosenings (30.1%), 22 polyethylene wears or breakages (19.5%), 5 stiffness (4.4%), 4 polyethylene dislocations (3.5%), 2 patellar dislocations (1.8%), 1 patellar component failure and 1 instability (0.9%, each). The mean interval from the index operation to the revision surgery was 59 months (1 month-20 years). Infection was the most common causes of revision TKA and followed by loosening, wear or breakage of polyethylene, stiff knee, dislocation of polyethylene and so on

Introduction. Removal of primary components during revision TKA procedure can damage underlying bone, resulting in defects that may need filled for stability of the revision reconstruction. Special revision components including cones and/or augments are often used to compensate for the missing bones. Little work has been done to characterize metaphyseal geometry in the vicinity of the knee joint, however, in order to motivate proper size and shape of cones and augments. The objective of this study was to use statistical shape modelling to evaluate variation in endosteal anatomy for revision TKA. Methods. Digital models of the femur and tibia were generated through segmentation of computed tomography scans, for the femur and the tibia (n∼500). Custom software was used to perform virtual surgery and statistical shape analysis of the metaphyseal geometry. A representative and appropriately sized revision femoral component was placed on each bone, assuming anterior referencing with an external rotation of 3 degrees from the posterior condyle axis. The outer and inner boundaries of the cortical bone were determined at the resection level and at 5 mm increments proximally, up to 40 mm. Similar analyses were performed on the tibia, using a typical revision resection (0 degrees medial and posterior slope), with outer and inner boundaries of the cortical bone were determined in 5 mm increments up to 40mm distal to the resection. Metaphyseal contours were exported relative to the central fixation feature of the implant, and average geometries were calculated based on size, and across the entire cohort. Principal Component Analysis (PCA) was used to quantify the variability in shape, specifically to evaluate the +/− 1 and 2 standard deviation geometries at each cross section level of Principal Component 1 (PC1). Results. Representative results illustrating the effect of size for the femur at single depth and the effect of depth and PC1 for tibia are reported. The average inner metaphyseal geometry of the femur (30mm proximal to resection) varied from 25.1×47.7 mm (AP x ML) at the smallest size to 54.5×78.0 at the largest size. The overall average tibia geometry decreased from 51.5×69.5 mm at the base resection level to 33.5×31.3 mm at the most distal resection level (40mm) distal to the resection. At the 20 mm level, the average tibia contour of 45.0×47.8 mm changed to 32.2×33.4 at −2 standard deviations of PC1 and 57.9×62.4 mm at the +2 standard deviations of PC1. Discussion. The generated contours can be used as a design input to optimize the shape of cones and augments, in order to fit potential defects in the femur and tibia encountered during revision TKA while respecting the anatomical constraints of the bone. Statistical shape analysis shows that these constraints are not strictly uniform scaling, based on bone size or on location in the metaphysis, but rather reflect variations in shape that may be used to optimize fit and stability of the prostheses

Introduction: Stiffness after primary total knee arthroplasty (TKA) is a severe complication that has been associated with excessive internal rotation of the femoral component. Methods: Between 2001 and 2004, 18 patients with 18 well-fixed, aseptic primary TKA underwent revision TKA at a single high-volume joint replacement center for stiffness in the presence of femoral component mal-rotation. Stiffness was defined as ROM with less than 90° of maximum flexion or a flexion contracture greater than 10°. Femoral component malrotation was defined as a condylar twist angle of more than 4° of internal rotation using CT scans. Following IRB approval, 17 out of 18 patients (median age at time of the index surgery 62.7 years, range 45 to 78; female, n=11; male, n=6) were available for retrospective outcome assessment. The mean time between primary and revision TKA was 3.2 years (range, 9–79 months). At a mean follow-up of 3.3 years (range, 2 to 6), all patients were evaluated clinically using the Knee Society objective and functional scores, and by CT measurement of femoral component rotation. Patients without additional procedures between primary and index revision TKA (group A, n=9) were compared using Student t-testing with those which had undergone additional interventions (group B, n=8). Results: Five patients had required additional procedures after the index revision TKA including closed manipulation under anesthesia in one case, patellar resurfacing in one case, metal removal after tubercle osteotomy and open debridement in another case, and tibial component revision followed by revision TKA in one case. CT scans after revision TKA revealed correction of femoral component rotation in all but one case from each group. After revision TKA, the mean objective score was overall 73 points, in group A 82 points compared to 63 points in group B (p< 0.001). In group A there were 78% excellent or good results compared to 13% in group B. The mean function score was overall 74 points, 78 points in group A compared to 69 points in group B. There were 67% good or excellent results in group A compared to 12% in group B. Mean flex-ion increased overall from 71 to 92 degrees (p< 0.01), in group A from 61 to 96 degrees (p< 0.01) and in group B from 82 to 89 degrees. Mean flexion contracture was reduced overall from 7 to 4 degrees, in group A from 6 to 3 degrees, and in group B from 8 to 5 degrees. Stiffness persisted in four cases (24%) (group A, n=1; group B, n=3). Satisfaction (VAS 0–100; 100=completely satis-fied) scored overall a mean of 52 points, in group A 57 points and in group B 44 points. Conclusion: Overall, revision TKA for knee stiffness associated with femoral component internal malrotation resulted in significantly improved knee motion. However, outcome was less predictable in those patients with additional procedures between primary and revision TKA

We identified 148 patients who had undergone a revision total knee replacement using a single implant system between 1990 and 2000. Of these 18 patients had died, six had developed a peri-prosthetic fracture and ten had incomplete records or radiographs. This left 114 with prospectively-collected radiographs and Bristol knee scores available for study. The height of the joint line before and after revision total knee replacement was measured and classified as either restored to within 5 mm of the pre-operative height or elevated if it was positioned more than 5 mm above the pre-operative height. The joint line was elevated in 41 knees (36%) and restored in 73 (64%). Revision surgery significantly improved the mean Bristol knee score from 41.1 (. sd. 15.9) pre-operatively to 80.5 (. sd. 15) post-operatively (p < 0.001). At one year post-operatively both the total Bristol knee score and its functional component were significantly better in the restored group than in the elevated group (p < 0.01). Overall, revision from a unicondylar knee replacement required less use of bone graft, fewer component augments, restored the joint line more often and gave a significantly better total Bristol knee score (p < 0.02) and functional score (p < 0.01) than revision from total knee replacement. Our findings show that restoration of the joint line at revision total knee replacement gives a significantly better result than leaving it unrestored by more than 5 mm. We recommend the greater use of distal femoral augments to help to achieve this goal

The amount of bone loss due to implant failure, loosening, or osteolysis can vary greatly and can have a major impact on reconstructive options during revision total knee arthroplasty (TKA). Massive bone loss can threaten ligamentous attachments in the vicinity of the knee and may require use of components with additional constraint to compensate for associated ligamentous instability. Classification of bone defects can be helpful in predicting the complexity of the reconstruction required and in facilitating pre-operative planning and implant selection. One very helpful classification of bone loss associated with TKA is the Anderson Orthopaedic Research Institute (AORI) Bone Defect Classification System as it provides the means to compare the location and extent of femoral and tibial bone loss encountered during revision surgery. In general, the higher grade defects (Type IIb or III) on both the femoral and tibial sides are more likely to require stemmed components, and may require the use of either structural graft or large augments to restore support for currently available modular revision components. Custom prostheses were previously utilised for massive defects of this sort, but more recently have been supplanted by revision TKA component systems with or without special metal augments or structural allograft. Options for bone defect management are: 1) Fill with cement; 2) Fill with cement supplemented by screws or K-wires; 3) Morselised bone grafting (for smaller, especially contained cavitary defects); 4) Small segment structural bone graft; 5) Impaction grafting; 6) Large prosthetic augments (cones); 7) Massive structural allograft-prosthetic composites (APC); 8) Custom implants. Maximizing support on intact host bone is a fundamental principle to successful reconstruction and frequently requires extending fixation to the adjacent diaphysis. Pre-operative planning is facilitated by good quality radiographs, supplemented on occasion by additional imaging such as CT. Fluoroscopically controlled x-ray views may assist in diagnosing the loose implant by better revealing the interface between the implant and bone and can facilitate accurate delineation of the extent of bone deficiency present. Part of the pre-operative plan is to ensure adequate range and variety of implant choices and bone graft resources for the planned reconstruction allowing for the potential for unexpected intra-operative findings such as occult fracture through deficient periprosthetic bone. Reconstruction of bone deficiency following removal of the failed implant is largely dictated by the location and extent of bone loss and the quality of bone that remains. While massive bone loss may compromise ligamentous attachment to bone, in the majority of reconstructions the degree of implant constraint needed for proper balancing and restoration of stability is independent of the bone defect. Thus some knees with minimal bone deficiency may require increased constraint due to the status of the soft tissues while others involving very large bone defects especially of the cavitary sort may be well managed with minimal constraint. Highly porous metal augments designed to reestablish metaphyseal support and function in the manner of a prosthetic structural graft have been introduced or are under development by several manufacturers. Published reports of short term experiences have been encouraging for both the tibial side and for femoral augmentation. It remains to be seen whether these implants will provide the desired longer term durability

Total knee arthroplasty is a predictable operation. Unfortunately, there is a subset of patients who do not well and require revision surgery. The surgical objective of revision total knee arthroplasty is the same as primary total knee arthroplasty: restore the original anatomy, restore function and provide a stable joint. The operation technique itself is a decisive for the success of arthroplasty as any type of malalignment may result in pain, instability or loosening of the implant. 1. REASONS OF FAILURE. The most important reason for revision total knee arthroplasty include aseptic loosening of one or both components. Early loosenings occur frequently as failures of ingrowth of a porous coated implant, while late loosenings mainly concentrate on cemented components, predominantly the tibial part. Another major reason for knee arthroplasties to fail is instability between the femur and tibia, caused by incorrect alignment or laxacity of the ligaments. Wear and osteolysis are the result of abnormally increased abrasion and plastic deformation of the polyethylene inlay. Usually this is a sequela of overloading through subluxation or deformity. It generally happens when the weight-bearing contact surfaces are small. Pain around the patella may occur due to anterior displacmenet of the patellofemoral joint and is not related whether the patella remains natural or is totally replaced. Rare complications are fatigue fractures of metallic components, femoral or tibial fractures around the implant, extreme limitation of motion or hyperextension of the joint. The most severe complication is periprosthetic infection, which in most of the cases requires a one or two-stage revision procedure to replace the implant. 2. GOALS OF REVISION SURGERY. Correct axial and rotational alignment including the restoration of the right joint line is mandatory for the success of a revision total knee arthroplasty. Especially joint line elevation can result in functional disorders, therefore the use of distal femoral augmentation in revision has given more attention. Balance of soft tissues to create equal flexion and extension spaces is another mandatory goal for revisions. Soft tissue releases can usually correct fixed angular deformities. Concerning balance by additional cuts of femoral or tibial bone one has to remember that adjustments on the femoral side can effect the knee in flexion or extension, whereas any adjustment on the tibial side will effect both. Minimize bone resection and achieving stability by stable fixation of all components of the implant are further prerequisits for the success of revision surgery. Another criteria for success is correct patella tracking, which can on the one hand be solved by soft tissue procedures or by revising the implant. Even one has to change the femoral and tibial component, retaining a well fixed patella component appears to be a suitable option. One of the most important criteria in revision total knee arthroplasty is implant selection. Recent publications have demonstrated that the implant-related failure rate was 25% when using implants designed for primary total knee arthroplasty, the failure rate of modified primary components was 14% and if components were used specially designed for revision the implant-related failure rate dropped to 6%. It was evident that revision implants exhibited superior performance and durability despite their use in more difficult reconstructions. Concerning wear and osteolysis one should consider that an isolated revision of an polyethylene insert should not be performed when there is accelerated wear of the insert with severe delamination and radiographically under surface osteolysis. The major objectives of bone grafting or augmentation blocks are filling in bony defects with biomechanically stable components to allow weight bearing and functional motion, to create an equal flexion and extension space for ligamentous stability and to restore a nearly anatomic joint line. The use of intramedullary stems at revision surgery provides fixation of components into diaphyseal bone leading to increased stability for reconstruction. It produces axial alignment, the stems also partially relieve stresses on the deficient metaphyseal bone or allograft. 3. TREATMENT OF INFECTION. The incidence of periprosthetic infections is rather low. In early infections antibiotic treatment combined with open arthrotomy including debridement and exchange of inlay are the treatments of choice. Late infections are best treated combining antibiotics and two stage exchange arthroplasty. Arthrodeses or amputations are extremely rare to indicate. 4. REVISIONS WITHOUT REPLACING THE IMPLANT. Many of these procedures belong to the patella including the removal of osteophytes, secondary release of the lateral patella retinaculum, secondary replacing the patella with an implant, or patellectomy. The replacement of a worn tibial inlay is often combined with secondary synovectomy, sometimes heterotopic ossifications need to be removed for the improvement of mobility. In infected knees the placement of an inflow/outflow drain in an attempt to manage an acute periprosthetic infection or to provide relief of pain in the presence of sepsis

Introduction. Presentation of our outcome in implant survival and clinical function using rotating-hinge knee prosthesis in revision total knee arthroplasty. Method. A retrospective review of 44 revision TKA containing 21 RHK (Biomet) and 23 MRH (Stryker). The patient population consisted of 27 women and 17 men with an average age of 75 years at the time of the revision. The mean follow-up period was 13 months. The clinical and functional results were evaluated according to the Knee-Society-Score (KSS) after 3, 6, 12, 24 and 36 months together with a x-ray. Results. The indication for the revision included aseptic loosening and ligamentous instability, 6 times as primary total knee replacement, an infected total knee in 6 cases and fractures with severe bone defect in 4 cases. The KSS pain improved from 49 (range 23–70) to 76 (range 34–98). The KSS function did not show any significant improvement of 60 (range 10–55) to 65 (range 20–100). The ROM improved with 53% from 74 (range 50–110) to 113 (range 65–130). Our complications have been revisions of hematoma in 4 cases, an infection/recurrence of infection in 2 cases with following explantation. There were 3 ligamentum patellae ruptures, 2 times due to rheumatoid arthritis, once due to Mb. Parkinson. We noticed 2 cases with peronaeus paresis (once temporarily) and one Guillain-Barre-Syndrom. With our x-rays we observed radiolucent lines without any progression or loosening factor for the prosthesis. Conclusion. We have seen good results using RHK and MRH in function and particularly a very good stability even for loss of collateral ligaments or massive bone loss. We evaluated a reduction of pain and an improvement of ROM although we had a number of revisions because of infection and co-morbidities

Introduction. Total knee arthroplasty (TKA) is a proven treatment method for advanced knee arthritis in terms of pain relief, function restoration, and quality-of-life improvement. The TKA use has increased significantly over the past decade and the growing rate is more prominent in Asian countries. Thus, the revision TKA may also increase in recent days, which represents a burden to the national health care system. To the best of our knowledge, little information is currently available regarding the incidence and related factors of revision TKA in Asian countries on the basis of nationwide database. This study sought to find the incidence of revision TKA and related factors in South Korea using national database from 2007 to 2012. Material and Method. Data collected by the Health Insurance Review Agency of Korea, from 260,068 TKA patients between 2007 and 2012, were used to estimate the incidence of revision TKA according to age group, gender and hospital TKA and manufacturer prosthesis volume (i.e., the number of TKA procedures carried out at a given hospital, and the number of procedures performed using a given manufacturer's prosthesis, respectively). Age group and hospital and manufacturer volumes were categorized into three groups and TKA incidence rates were computed for groups stratified according to age, gender and hospital and manufacturer volumes. Result. Incidence rates per 100,000 person-years were as follows: 1) by age: < 65 years, 447.2; 65–74 years, 363.7; ≥ 75 years, 270.9, 2) by gender: male, 537.8; female, 346.1; 3) by hospital volume (procedures/year): < 20, 536.9; 20–199, 432.3; ≥ 200, 300.1; and 4) by manufacturer volume (prostheses/year): < 1500, 772.3; 1500–3999, 453.9; ≥ 4000, 345.6. TKA incidence rate in young males was significantly higher compared to that in elderly females. The difference in cumulative incidence, between hospitals with an annual volume of < 20 procedures and those with a volume of 20–199 procedures, was reduced for manufacturers with an annual volume of ≥ 4000. Similarly, the difference in cumulative incidence between manufacturers with an annual volume of < 1500 and those with a volume of 1500–3999 was reduced in hospitals with an annual volume of ≥ 200. Conclusions. Revision TKA incidence varied according to age, gender and hospital and manufacturer volumes. This data could inform clinical decisions and healthcare strategies

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

Aims. The aim of this study was to establish the results of isolated exchange of the tibial polyethylene insert in revision total knee arthroplasty (RTKA) in patients with well-fixed femoral or tibial components. We report on a series of RTKAs where only the polyethylene was replaced, and the patients were followed for a mean of 13.2 years (10.0 to 19.1). Patients and Methods. Our study group consisted of 64 non-infected, grossly stable TKA patients revised over an eight-year period (1998 to 2006). The mean age of the patients at time of revision was 72.2 years (48 to 88). There were 36 females (56%) and 28 males (44%) in the cohort. All patients had received the same cemented, cruciate-retaining patella resurfaced primary TKA. All subsequently underwent an isolated polyethylene insert exchange. The mean time from the primary TKA to RTKA was 9.1 years (2.2 to 16.1). Results. At final follow-up, 13 patients had died, leaving 51 patients for study. Only seven of these patients had required re-operation. Knee Society scores (KSS) prior to RTKA were a mean of 78.4 (24 to 100). By six weeks post-revision, the mean total KSS was 93.5 (38 to 100) and at final follow-up, they had a mean of 91.6 (36 to 100). Conclusion. In appropriate circumstances, where the femoral and tibial components are satisfactorily aligned and well fixed, and where the soft tissues can be balanced, a polyethylene exchange alone can provide a durable solution for these RTKA patients. Cite this article: Bone Joint J 2019;101-B(7 Supple C):104–107

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

We report a consecutive series of 16 revision total knee arthroplasties using the Total Condylar III system in 14 patients with inflammatory arthritis which were performed between 1994 and 2000. There were 11 women and three men with a mean age of 59 years (36 to 78). The patients were followed up for 74 months (44 to 122). The mean pre-operative Knee Society score of 37 points (0 to 77) improved to 88 (61 to 100) at follow-up (t-test, p < 0.001) indicating very good overall results. The mean range of flexion improved from 62° (0° to 120°) to 98° (0° to 145°) (t-test, p < 0.05) allowing the patients to stand from a sitting position. The mean Knee Society pain score improved from 22 (10 to 45) to 44 (20 to 50) (t-test, p < 0.05). No knee had definite loosening, although five showed asymptomatic radiolucent lines. Complications were seen in three cases, comprising patellar pain, patellar fracture and infection. These results suggest that the Total Condylar III system can be used successfully in revision total knee arthroplasty in inflammatory arthritis

Introduction. Porous metaphyseal cones are increasingly used for fixation in revision total knee arthroplasty (RTKA). Both cemented shorter length stems and longer diaphyseal engaging stems are currently utilized with metaphyseal cones with no clear evidence of superiority. The purpose of this study was to evaluate our experience with 3D printed titanium metaphyseal cones with both short cemented and longer cementless stems from a clinical and radiographic perspective. Methods. In total 136 3D printed titanium metaphyseal cones were implanted. The mean patient age was 63 and 48% were female. The mean BMI was 33 and the mean ASA class was 2.5. There were 42 femoral cones in which 28 cemented and 14 cementless stems were utilized. There were 94 tibial cones in which 67 cemented and 27 cementless stems were utilized. The choice for stem fixation was surgeon dependent and in general cones were utilized for AORI type 2 and 3 bone defects on the femur and tibia. The most common fixation scenario was short cemented stems on both the femur and tibia followed by cemented stem fixation on the tibia and cementless fixation on the femur. Clinical data such as revision, complication, and PRO was collected at last follow-up (minimum follow-up 1 year). Radiographic analysis included cone bony ingrowth and coronal and sagittal alignment on long-standing radiographs. Descriptive statistics were used to compare demographics between patients who had malalignment (HKA beyond +/− 3 degrees and flexion/extension beyond +/− 3 degrees). Adjusted logistic regression models were run to assess malalignment risk by stem type. Results. Patient reported outcomes demonstrated modest improvements with Pre-op KOOS improving from 44 pre-op to 59 post -op and PF-CAT improving from 33 to 37 post-op. PROMIS pain scores decreased significantly from 54 to 44 post-op. 36% of patients had malalignment in either the coronal or sagittal plane. Patients with malalignment were more likely to be female (66.7% vs 40.4%, p-value=0.02). After adjusting for age, sex and BMI, there was a significantly increased risk for coronal plane malalignment when both the femur and tibia had cementless compared to cemented stems (odds ratio=5.54, 95%CI=1.15, 26.80). There was no significantly increased risk when comparing patients with mixed stems to patients with cemented stems. Sagittal plane malalignment was more common with short cemented stems although both coronal plane and sagittal plane malalignment with either stem type was not associated with inferior clinical outcome. Overall cone survivorship was excellent with only two cones removed for infection. Conclusion. Metaphyseal titanium cones provide reliable fixation in revision TKA. However, PROs in this complex patient population show only modest improvement consistent with other variables such as co-morbidities and poor baseline physical function. Small cone inner diameter may adversely influence cementless stem position leading to coronal plane malalignment. Short cemented stems are subject to greater sagittal plane malalignment with no apparent influence on clinical outcome

Many surgeons consider revision total knee arthroplasty (TKA) a difficult procedure, calling for flexibility and improvisation. However, revision TKA can be broken into a number of consecutive steps that need to be performed. Setting up a reproducible and stepwise approach is mandatory for the surgeon who performs this procedure more or less regularly. At our institution, we have followed a five-step protocol in performing 166 revision TKA procedures. Its relatively strict guidelines leave little room for intraoperative improvisation. Our protocol covers exposition, implant extraction, implant selection, bone preparation and dealing with bony defects. There has been acceptable ‘on the table’ reconstruction in all cases

Patella resurfacing in revision total knee arthroplasty is a controversial issue. While performing revision TKA we must consider some different situations: previously resurfaced patella or not, in case of resurfaced patella, if it is fix or loosened, in case of loosened patella is there a bone loss or not. If patella wasn’t previously resurfaced, we can preserve natural patella performing at least a regularization of its osteophytes, or we can realize a primary resurfacing. If patella was previously resurfaced and still well fixed, we preserve domed component if not grossly damaged. Its revision is performed if it is damaged or not congruent. If patella was previously resurfaced and loosened the two possibilities are the revision or the retention of the bony patella. In case of previously resurfaced and loosened patella, with severe bone loss, we can preserve the bony shell, or we can realize revision with the use of cortical grafting or we can performa patelloplasty, or complete patellectomy. Finally, in these cases it’s possible the revision with tantalum patella. Outcomes of patella resurfacing in revision total knee arthroplasty are usually fair: low functional and pain scores, quadricipite leverage loss, worse patellar tracking, anterior pain, patellar fractures, knee stiffness

Following a careful in-depth preoperative plan for revision TKA, the first surgical step is adequate exposure. It is crucial to plan your exposure for all contingencies. Prior incisions have tremendous implications and care must be taken to consider their impact. Due to the medially based vascular supply to the skin and superficial tissues about the knee, consideration for use of the most LATERAL incision should be made. It is essential to avoid the development of flaps which may compromise the skin and soft tissue which can have profound implications. Exposure options can be broken down into either PROXIMALLY based techniques or DISTALLY based options. The proximal based techniques involve a medial parapatella arthrotomy followed by the establishment of medial and lateral gutters. An assessment of the ability to evert or subluxate the patella should be made. Care must be taken to protect the insertion of the patella tendon into the tibial tubercle. If the patella is unable to be mobilised, then extension of arthrotomy proximal is performed. If this is not adequate, then consider inside out lateral release. If still unable to mobilise, then a QUAD SNIP is performed. In rare instances, you can connect the lateral release with quad snip resulting in a V-Y quadplasty, which results in excellent exposure. Another option is to employ DISTALLY based techniques such as the tibial tubercle osteotomy technique described by Whiteside. A roughly 8cm osteotomy segment with distal bevel is performed. The osteotomy must be at least 1.5–2cm thick: too thin and risk of fracture increases. This approach leaves the lateral soft tissues intact and then a “greenstick” of the lateral cortex is performed with eversion of patella and the lateral sleeve of tissue. This technique is excellent for not only exposure but also in instances where tibial cement or a cementless tibial stem needs to be removed. Closure is accomplished with wires either through the canal or around the posterior cortex of the tibia

Revision total knee replacement is becoming a more common procedure. Landmarks commonly used for alignment are often distorted by the cause of the failure or removing the components themselves. This can make correct alignment and re-creation of joint line height difficult. We looked at consecutive knee replacements that underwent revision surgery over one year. All cases had revision total knee replacements by the senior author using the Stryker® Navigation System. All cases were assessed radiographically post-operatively with long leg Maquet views. The tibial and femoral component varus/ valgus angles taken from the mechanical axis and the mechanical tibio-femoral angle were measured. On long leg Maquet views the mean mechanical tibio-femoral angle was 3.25 with a range from 0 to 6, the mean tibial component angle was 90.4 with a range of 89 to 92 and the mean femoral component angle was 90.3 with a range of 89 to 91. Computer navigation in revision total knee replacement is a safe procedure that gives reproducible results. Postoperative alignment, as measured radiographically, gave good results with tibial and femoral components within 2 degrees to the perpendicular of the mechanical axis. We feel that navigation is helpful in obtaining accurate positioning of components in revision knee surgery

We have previously developed a radiographic technique, the oblique posterior condylar view, for assessment of the posterior aspect of the femoral condyles after total knee arthroplasty. The purpose of this study was to confirm the validity of this radiographic view based upon intra-operative findings at revision total knee arthroplasty. Lateral and oblique posterior condylar views were performed for 11 knees prior to revision total knee arthroplasty, and radiolucent lines or osteolysis of the posterior aspect of the femoral condyles were identified. These findings were compared with the intra-operative appearance of the posterior aspects of the femoral condyles. Statistical analysis showed that sensitivity and efficacy were significantly better for the oblique posterior condylar than the lateral view. This method can, therefore, be considered as suitable for routine follow-up radiographs of the femoral component and in the pre-operative planning of revision surgery

Summary. Revision TKA using CCK prosthesis showed comparable outcome to PS prosthesis in clinical and radiological results. Introduction. In revision total knee arthroplasty (TKA), the goal should be to obtain good motion, function and most importantly stability. The stability depends on remaining soft tissue and implant design. The more the ligaments retain function, the less the implant constraint is needed to achieve stability. With increased constraint, the transfer of joint reaction forces to implant-bone interface may lead to mechanical loosening of the implant. Constrained condylar knee (CCK) prosthesis provides more constraint compared with posterior stabilized (PS) prosthesis. The purpose of this study was to compare the clinical, radiological outcome and survivorship of CCK and PS prosthesis in revision TKA. Materials and Methods. One hundred and twenty-one consecutive revision TKAs using CCK (79 knees) and PS (42 knees) were included. The mean follow-up period was 63.2 months for CCK and 64.8 months for PS. The mean age was 69.5 years and 70.6 years in CCK and PS, respectively. Range of motion (ROM), American Knee Society (AKS) score, Hospital for Special Surgery (HSS) score, complications and failure rate were assessed. Radiographic measurements included tibiofemoral angle and radiolucent lines. The Kaplan-Meier survivorship analysis was performed with an end point of re-revision surgery for any reason and compared between CCK and PS using the Log-rank test. Results. The mean range of motion improved from 97.5° to 115.9° in PS, from 89.5° to 110.1° in CCK. The mean Knee Society knee and functional scores improved from 47.6 and 36.4 to 89.7 and 66.1 with PS, from 53.5 and 41.7 to 79.2 and 66.8 with CCK. The mean Hospital for Special Surgery knee score also improved from 57 to 76.9 and 59.7 to 77.6, respectively. The complication rate was 7.5% (4 cases; 3 recurred infections, 1 instability) in PS and 10.3% (7 cases; 4 recurred infections, 1 periprosthetic fracture, 2 stem tip pains) in CCK. The Kaplan–Meier survivorship analysis revealed that ten year survival of the components was 85.4% for PS and 80.0% for CCK. In all aspects, there were no statistical difference (a p-value of more than 0.05) between PS and CCK. Conclusion. Revision TKA using CCK prosthesis showed comparable outcome to PS prosthesis in clinical and radiological results. CCK prosthesis is a reliable and successful option for prosthesis selection in revision TKA when PS prosthesis is not enough for management of instability

Introduction: Common failure modes of revision total knee arthroplasty (TKA) include aseptic component loosening and damage to constraining mechanisms which are often required in revision TKA. Mobile-bearing (MB) revision TKA components have been developed in hopes of lessening these failure mechanisms. Our objective was to evaluate the early clinical outcomes for the use of MB in revision TKA with a minimum 2-year follow-up and to evaluate bearing complications. Methods: Retrospective clinical and radiographic evaluation of 84 MB revision TKAs with minimum 2-year follow-up was performed. Revision TKAs were performed using PFC Sigma and LCS revision rotating platform implants (Depuy, Warsaw, IN). Indications for revision include aseptic loosening (31 knees), instability (30 knees), failed unicompartmental knee replacement (8 knees), infection reimplantation (7 knees), arthrofibrosis (3 knees), chronic hemarthrosis (3 knees), failed patellofemoral replacements (1 knees), and nonunion of a supracondylar femur fracture (1 knee). Results: At a mean follow-up of 3.7 years, the average Knee Society clinical and function scores had increased from 50.3 points preoperatively to 89.1 points and from 49.3 points to 80.1 points, respectively. Average motion improved from 99.8° preoperatively to 116.5° postoperatively. Radiographic review demonstrated excellent fixation with no evidence of component loosening upon latest follow-up. No cases of bearing instability were observed. Conclusion: This evaluation of 84 MB revision TKAs has demonstrated favorable early results at a mean follow-up of 3.7 years with no occurrence of bearing instability. Longer follow-up is required to evaluate for potential advantages of reducing polyethylene wear, lessening fixation stresses, and protection of constraining mechanisms

The use of stems in revision TKA enhances implant stability and thus improves the survival rate. Stemmed components obtain initial mechanical stability when there is deficient metaphyseal bone. However the optimal method of stem fixation remains controversial, which includes selection of stem size, length or the use of cemented vs. cementless stems. Although postulated by many surgeons, there is no sufficient evidence, that cementless or hybrid fixation does perform better in the long term outcome, than cemented stems. In addition a number of studies, even from the U.S., suggested that there might be a benefit for the long term survival for cemented stems in revision TKA. Obviously cemented stems have some few advantages in revision set up as: topic antibiotic delivery and initial strong fixation. While main disadvantages arise during limited/poor bone quality for initial cancellous bone-cement fixation; revision with removal of a long cement mantle and re-cementing into a previously cemented canal. Furthermore removing a fully cemented implant can be much more time consuming. The Endo Klinik has currently over 30 years of experience utilising cemented stems in combination with a rotating hinge implant in revision TKA, including satisfactory long-term results. However we are aware of this technique associated limitations, including aseptic loosening and further conversion to a re-revision with necessary impaction bone grafting. Generally it has to be mentioned, that type of stem and reconstruction type if often driven by surgeons own and institutional preference

Introduction. Revision total knee arthroplasty (TKA) has been often used with a metal block augmentation for patients with poor bone quality. However, bone defects are frequently detected in revision TKA used with metal block augmentation. This study focused on identification of a potential possibility of the bone defect occurrence through the evaluation of the strain distribution on the cortical bone of the tibia implanted revision TKA with metal block augmentation, during high deep flexion. Materials and Methods. Composite tibia finite element (FE) model was developed and revision TKA FE model with a metal block augmentation (Baseplate size #5 44AP/67ML, Spacer size #5 44AP/67ML, Stem size Φ9, L30, Augment #5 44AP/67ML thickness 5mm) was integrated with the composite tibia FE model. 0°, 30° 60°, 90°, 120° and 140° flexion positions were then considered with femoral rollback phenomenon [Fig 1.A]. A compressive load of 1,600N through the femoral component was applied to the composite tibia FE model integrated with the tibia component, sharing by the medial and lateral condyles, simulating a stance phase before toe-off [Fig 1.B]. Results and Discussions. The strain distribution on the cortical bone of the tibia was shown in [Fig 2]. The results showed that the strains on the posterior region were gradually increased from extension to high deep of the knee joint and generally larger than the other regions. This fact was favorably corresponded to the femoral rollback phenomenon in the knee joint, showing a good accuracy of our FE model. In contrast to the results on the posterior region, the strains on the medial region were gradually decreased after 60° or 90° flexion position and relatively lower than the other regions. Particularly, the strains on the medial region were generally lower than 50–100 µstrain, which is known as critical value range able to inducing bone loss, during high deep flexion. This fact indicate that a potential possibility of bone defect occurrence in revision TKA used with a metal block augmentation may be relatively increased in patients who are frequently exposed to a personal lifestyle history with the loading conditions of the high flexion. This study may be valuable by identifying for the first time a potential possibility of the bone defect occurrence through evaluation of the strain distribution beneath metal block augmentation in revision TKA used with a metal block augmentation during high deep flexion. Conclusions. A potential possibility of bone defect occurrence in revision TKA used with a metal block augmentation may be dependent on loading patterns applied on the knee joint related to personal lifestyle history. Particularly, it may be relatively increased in patients who are frequently exposed to a personal lifestyle history with the loading conditions of the high flexion. Acknowledgements. This study was supported by a grant from the New Technology Product Evaluation Technical Research project, Ministry of Food and Drug Safety (MFDS), Republic of Korea

Purpose. Most of revision TKA needs bone reconstruction. The success of revision TKA depends on how well the bone reconstruction can be done. The method of reconstruction includes bone cementing, metal augmentation, allogenic bone graft, APC and tumor prosthesis, etc. In moderate to severe bone defect, allograft is needed. However, allogenic bone graft is surgically demanding and needs long operation time, which is very risky to the elderly patients. The authors revised an alternative method of bone defect reconstruction using cementing method with multiple screws augmentation. Methods. There were 12 cases of patients with large defect which could not be reconstructed with metal augment from April 2012 to April 2014. The authors performed 3 to 5 screws fixation on the defect site. Sclerotic bone is prepared with burring for better cementing. 3 ∼ 5 screws according to the size of defect. The length of screw fixation was determined as deep to the bone until stable fixation just beneath the implant. When drilling for the screw insertion, intramedullary guide is put into the medullary canal so as not to interfere with implant insertion. The defect is filled with cement during prosthesis fixation. Weight bearing was permitted on postoperative 3rd day, as usual manner of primary TKA. Results. According to the AORI classification, there were 10 cases of 2A and 2 cases of 2B. Mean follow up period was average 15 months. The number of screw insertion was 4.3 ea (2∼8). Average operation time was 1 hour and 57 minutes. Mean ROM was 107.9. HSS score, KSS score ad WOMAC score were 86.3, 92.8 and 11, respectively. There were no case of infection and loosening at the last follow-up. Conclusion. Cementing with multiple screws augmentation technique is a good alternative of bone reconstruction

Introduction. Previous studies have demonstrated that higher volume hospitals have better outcomes following revision total knee arthroplasty (rTKA), in current literature there are no reports investigating the effect of surgeon volume. The purpose of this study is to investigate if patients of high-volume revision surgeons have better outcomes following rTKA as compared to patients of low volume surgeons. Methods. This retrospective observational analysis examined the rTKA database at a large urban academic medical center for aseptic, unilateral rTKA between January 2016 and March 2019 with at least 1-year of follow-up. Surgeon operative volume during the same time period was evaluated. Surgeons who performed at least 18 aseptic rTKA per year were considered high volume (HV), whereas surgeons who performed fewer than 18 aseptic rTKA per year were considered low volume (LV). Demographics, surgical factors, and post-operative outcomes were collected and compared between the two cohorts. A post-hoc power analysis was conducted for full revisions (1-ß=0.909, α=0.05). Results. 307 cases were identified: 177 performed by LV surgeons and 130 performed by HV surgeons. The only demographic difference was a greater proportion of non-smokers in the LV cohort (59.4% vs. 50.0%; p=0.031). Patients of HV surgeons were more likely to receive a full revision (64.6% vs. 47.5%; p<0.001). For all revisions, HV surgeons had shorter surgical times by about 17 minutes (p=0.010). For the 168 full revisions (84 HV, 84 LV), patients of HV surgeons had shorter hospital stays (2.92±1.62 vs. 3.57±2.69 days; p=0.048), shorter surgical times (131.42±33.86 vs. 171.65±49.88 minutes; p<0.001), lower re-revision rates (7.1% vs. 19.0%; p=0.038), and fewer re-revisions (0.07±0.26 vs. 0.29±0.74 re-revisions; p=0.018). Conclusions. Patients of HV revision surgeons have better outcomes following full rTKA. These findings support the development of revision teams within arthroplasty centers of excellence to offer patients the best possible outcomes following rTKA

There has been speculation as to how the outcome of revision total knee arthroplasty (TKA) compares with that of primary TKA. We have collected data prospectively from patients operated on by one surgeon using one prosthesis in each group. One hundred patients underwent primary TKA and 60 revision TKA. They completed SF-12 and WOMAC questionnaires before and at six and 12 months after operation. The improvements in the SF-12 physical scores and WOMAC pain, stiffness and function scores in both primary and revision TKA patients were highly statistically significant at six months. There was no statistically significant difference in the size of the improvement in the SF-12 physical and WOMAC pain, stiffness and function scores between the primary and revision patients at six months after surgery. The SF-12 mental scores of patients in both groups showed no statistically significant difference after surgery at the six- and 12-month assessments. Our findings show that primary and revision TKA lead to a comparable improvement in patient-perceived outcomes of physical variables in both generic and disease-specific health measures at follow-up at one year

Patient satisfaction is not uniform or consistent following revision total knee arthroplasty. This study evaluates ninety-nine patients with a self-administered patient satisfaction questionnaire at a minimum of two years following the revision procedure (1997–99) to determine differences between satisfied (sixty-six patients) and dissatisfied patients (thirty-three patients). Univariate analysis revealed that patients satisfied with their results were significantly different (p< .05) than dissatisfied patients with regards to post op scores including those of the WOMAC pain and function, oxford, and SF-12. Patients were not different with regards to (p> .05) age, comorbidity score, surgical approach, or sepsis as a reason for the revision procedure. Regression analysis demonstrated that gender, post-op WOMAC score, and pre-op arc of motion were significant determinants of satisfaction. The purpose of this study is to evaluate determinants of patient satisfaction following revision total knee arthroplasty. Patient satisfaction with revision knee surgery is most strongly associated with both pre and post-operative descriptors of knee function as well as gender. Understanding the variables associated with satisfaction/dissatisfaction following revision knee arthroplasty may further assist ongoing research efforts to improve the outcomes of this procedure. Univariate analysis revealed that patients satisfied with their results were significantly different (p< .05) than dissatisfied patients with regards to WOMAC pain and function score, oxford knee score, and SF-12. Patients were not different with regards to (p> .05) age, comorbidity score, surgical approach, or presence of sepsis as a reason for the revision procedure. Regression analysis demonstrated that gender, post-op WOMAC score, and pre-op arc of motion were significant determinants of satisfaction (p< .05). A self-administered patient satisfaction survey was completed by ninety-nine patients at a minimum of two years following revision total knee arthroplasty. Fifty-nine patients were females and forty were males. Sixty-six patients were satisfied and thirty-three patients were dissatisfied with the outcome of their surgery at two years post-op. Univariate analysis and multivariate regression suggest that pre and post-operative joint function and gender are the most significant determinants of patient satisfaction

Backgroud: Revision total knee arthroplasty (TKA) consumes considerably more resources than primary TKA. Management of infected arthroplasty has been shown to require even more resources in terms of inpatient stay, microbiological investigation, multiple stage procedures and more complex implants than treatment of aseptic failures. We investigated the trends in cost of revision TKA over a 10 year period. Patients and Methods: Between 1997 and 2006, 189 patients underwent revision total knee arthroplasty in our institution. The perioperative data was available for 181 of these (95.77%). Data collected included age, gender, diagnosis, number of revisions length of stay, operative time, blood loss, number of units of blood transfused and ASA grade. Financial data included cost of implants and instrumentation, cost and number of bed-days, investigations and treatment. In the case of 2 stage revisions involving 2 admissions, the cumulative data was compiled as a single episode. Results: The study group comprised 123 females (65.07%) and 66 males (34.93%). The mean age for both groups was 68.97 (range of 20 to 91years), with a 6.7% increase in mean age over the ten year period (66.75 to 71.19). The mean ASA score dropped from 2.67 in 1997 to 2.23 in 2006. The number of revision surgeries per year increased over the study period from 8 to 36. The number of TKA revisions for infection over the 10 years was 18(9.5%). The mean length of stay for revision due to aseptic loosening in 1997 was 14.3 days. The average length of stay for revision for infected arthroplasty was 35 days. In 2006, the length of stay increased to 65 days for infected arthroplasty and 15.03 days for aseptic cases. The mean total cost of aseptic revision per patient was 12,409.92 (range 8,822.58–13,559.65) euro in 1997 with revisions for infection costing 20,888.66 euro, a difference of 68.32%. The industry cost of implants increased by 32–35% (€3119–€4371 and €4216–€5800) between 1999 and 2006 depending on implant selection. There was a 20– 42% increase in generic hospital costs (admission, investigation and treatment related costs) in the same period. Conclusion: With increasing life expectancy and increased indication for primary arthroplasty more patients are coming to revision surgery. The cost of Revision TKR has increased steadily over the last 10 years. Revision TKR for infection remains significantly more expensive than revision for aseptic loosening or other causes and provides a significant financial burden on orthopaedic services. Infected arthroplasty incurs significantly greater cost and every precaution should be taken to avoid infection in total knee arthroplasty

Aims. Enhanced perioperative protocols have significantly improved patient recovery following primary total knee arthroplasty (TKA). Little has been investigated the effectiveness of these protocols for revision TKA (RTKA). We report on a matched group of aseptic revision and primary TKA patients treated with an identical pain and rehabilitation programmes. Methods. Overall, 40 aseptic full-component RTKA patients were matched (surgical date, age, sex, and body mass index (BMI)) to a group of primary cemented TKA patients. All RTKAs had new uncemented stemmed femoral and tibial components with metaphyseal sleeves. Both groups were treated with an identical postoperative pain protocol. Patients were followed for at least two years. Knee Society Scores (KSS) at six weeks and at final follow-up were recorded for both groups. Results. There was no difference in mean length of stay between the primary TKA (1.2 days (0.83 to 2.08)) and RTKA patients (1.4 days (0.91 to 2.08). Mean oral morphine milligram (mg) equivalent dosing (MED) during the hospitalization was 42 mg/day for the primary TKA and 38 mg/day for the RTKA groups. There were two readmissions: gastrointestinal disturbance (RTKA) and urinary retention (primary TKA). There no were reoperations, wound problems, thromboembolic events or manipulations in either group. Mean overall KSS for the RTKA group was 87.3 (45 to 99) at six-week follow-up and 89.1 (52 to 100) at final follow-up (mean 3.9 years, (3.9 to 9.0)). Mean overall KSS for the primary group was 89.9 (71 to 100) at six-week follow-up and 93.42 (73 to 100) at final follow-up (mean 3.5 years (2.5 to 9.2)). Conclusion. An identical pain and rehabilitation protocol used for primary TKA patients can enable certain full-component aseptic RTKA patients to have a similar early functional outcome. Cite this article: Bone Joint J 2020;102-B(6 Supple A):96–100

Objectives. Initial stability of tibial trays is crucial for long-term success of total knee arthroplasty (TKA) in both primary and revision settings. Rotating platform (RP) designs reduce torque transfer at the tibiofemoral interface. We asked if this reduced torque transfer in RP designs resulted in subsequently reduced micromotion at the cemented fixation interface between the prosthesis component and the adjacent bone. Methods. Composite tibias were implanted with fixed and RP primary and revision tibial trays and biomechanically tested under up to 2.5 kN of axial compression and 10° of external femoral component rotation. Relative micromotion between the implanted tibial tray and the neighbouring bone was quantified using high-precision digital image correlation techniques. Results. Rotational malalignment between femoral and tibial components generated 40% less overall tibial tray micromotion in RP designs than in standard fixed bearing tibial trays. RP trays reduced micromotion by up to 172 µm in axial compression and 84 µm in rotational malalignment models. Conclusions. Reduced torque transfer at the tibiofemoral interface in RP tibial trays reduces relative component micromotion and may aid long-term stability in cases of revision TKA or poor bone quality. Cite this article: Mr S. R. Small. Micromotion at the tibial plateau in primary and revision total knee arthroplasty: fixed versus rotating platform designs. Bone Joint Res 2016;5:122–129. DOI: 10.1302/2046-3758.54.2000481

Methodology: A retrospective review based on a prospective database was performed on 146 consecutive revision TKA’s. An independent observer measured clinical outcomes using the Knee Society Knee (KS) and Function Score (FS). X-ray evaluation, including rating of radiolucent lines, tibiofemoral and patellofemoral alignment, was carried out by an independent radiologist. ANOVA was used for statistical analysis, with significance set at p≤0.05 (SPSS version 15.0). Post-hoc Bonferroni testing was carried out for single variables including primary cause of failure, age at revision surgery, time span between index operation and revision, type of index operation, partial or total revision and the performance of a tuberosity osteotomy. Results: 146 files were available in 135 patients. 16 patients deceased (17 knees) during the follow-up period and 2 patients (2 knees) were lost to follow-up. 117 patients (127 knees) were available for evaluation. Age at revision surgery averaged 67.7 years (range 32.3–88.1). Mean follow-up time was 4.5 years (range 1–14). Patients had revision TKA between 51 days and 16.1 years (average 4.7 years) after the index TKA. 54% of the early revisions were due to infection and instability, 55% of late revisions were caused by polyethylene-wear and loosening. The mean postoperative KS was 70.8 with a mean improvement of 43.2 points as compared to pre-operative. The mean postoperative FS was 52.9 with a mean improvement of 25.4 points. Grouping outcomes according to cause of failure of the index TKA gave the following ranking from better to worse, without being significant: wear (n=15; KS 80.8; range 43–99, SD 17.5), loosening (n=44; KS 75.8; range 15–100, SD=21.2), malalignment (n=19; KS 70.0; range 9–95, SD 25.9), instability (n=33; KS 68.2; range 5–100, SD 24.1), others (n=16; KS 66.7; range 10–100, SD 25.9), and infection (n=21; KS 64.2; range 3–100, SD 31.7). Survivorship at 5 years was 90.0% (CI 86.4% –93.6%), at 10 years 84,6% (CI 77.0% –92.3%) and at 14 years 84,6% (CI 37.7% –131.6%). Significant better outcomes were seen with late revisions, index operation being partial knee replacement and older age at revision. More failures (p=0.002) were seen with early revisions. In 32.6% of the patients radiolucent lines of ≥1 mm were observed. Points were granted with the use of a Radiolucency Scoring Scheme. Patients with less than 4 points (n=87, mean KS 71.2) had better outcomes than patients with 4 or more points (n=8, mean KS 56.4). 87% of patients were aligned within 4° of mechanical axis. Conclusion:. Outcomes of revision TKA are inferior to primary TKA. Early failures were mainly caused by infection, instability, malalignment. Grouping revision TKA’s to etiology of failure did not lead to significant differences in outcomes. Significant better outcomes were reported for late revisions, patients with older age at revision surgery and partial knee replacement. Survivorship analysis was significally better for late than for early revisions

Background. Revision total knee arthroplasty (rTKA) is a high stakes procedure with complex equipment and multiple steps. For rTKA using the ATTUNE system revising femoral and tibial components with sleeves and stems, there are over 240 pieces of equipment that require correct assembly at the appropriate time. Due to changing teams, work rotas, and the infrequency of rTKR, scrub nurses may encounter these operations infrequently and often rely heavily on company representatives to guide them. In turn, this delays and interrupts surgical efficiency and can result in error. This study investigates the impact of a fully immersive virtual reality (VR) curriculum on training scrub nurses in technical skills and knowledge of performing a complex rTKA, to improve efficiency and reduce error. Method. Ten orthopaedic scrub nurses were recruited and trained in four VR sessions over a 4-week period. Each VR session involved a guided mode, where participants were taught the steps of rTKA surgery by the simulator in a simulated operating theatre. The latter 3 sessions involved a guided mode followed by an unguided VR assessment. Outcome measures in the unguided assessment were related to procedural sequence, duration of surgery and efficiency of movement. Transfer of skills was assessed during a pre-training and post-training assessment, where participants completed multi-step instrument selection and assembly using the real equipment. A pre and post-training questionnaire assessed the participants knowledge, confidence and anxiety. Results. All participants reported orthopaedics as their primary speciality with mean of 6-years experience. 80% reported they are ‘sometimes’ required to scrub for operations in which they do not feel comfortable with the equipment. All participants improved across the 3 unguided sessions reducing their operative time by 47%, assistive prompts by 75%, dominant hand motion by 28% and head motion by 36%. This transferred into the real-world: Participants completed 11.3% of tasks correctly in pre-training compared to 83.5% correct in the timely selection and assembly of rTKA equipment, post-training. All participants reported increased confidence and reduced anxiety after the training. Conclusion. Unfamiliarity with orthopaedic procedures or equipment is common for scrub nurses and can impact surgical performance. VR training improves their understanding, technical skills and efficiency in complex rTKA. These VR-learnt skills translate into the physical environment. This has important implications on how scrub nurses can be trained remotely, asynchronously and safely to perform complex orthopaedic surgery

Purpose. Although the use of stems in revision total knee arthroplasty (RTKA) enhances survival by improving the stability of implant, questions as to the optimal fixation method as well as the vertical extent of the cement, remain unanswered. This study aimed 1) to determine the correlation between the vertical extent of cement and implant loosening; and 2) to determine the minimum cementing extent for a stable implant in revision TKA with a hybrid technique. Materials and Methods. We retrospectively analyzed 109 stemmed RTKAs with average follow-up of 63 months. In each case, a single varus-valgus constrained implant was used and fixed with a hybrid technique. During surgery, stem was partially covered with cement beyond stem-implant junction. Stability of implant was evaluated according to the modified Knee Society Radiographic Scoring System. Cementing extent was defined as length from implant base to the end of the radiopaque line around the stem. The correlation between the vertical cementing extent and implant stability was analyzed, and the minimal vertical cementing extent for a stable implant was evaluated with a scatter plot. Results. The vertical cementing extent was longer in stable implants (femur: P=.002, tibia:P=.007) and the correlation between the vertical cementing extent and implant stability was significant (femur:P<.001, tibia:P=.001). Logistic regression analysis found that the risk of loosening was 8.7 times higher if the cementing extent was less than 40mm (tibia=16.1 times). The minimal vertical cementing extent for a stable implant in femur was estimated to be 65mm for middle stem (40% of total implant length) and 50mm for long stem (25% of total implant length). For tibia, it was 55mm for middle stem (45% of total implant length) and 40mm for long stem (25% of total implant length). Conclusion. We confirmed that a negative correlation exists between the radiolucent line and the cementing extent in stemmed revision TKA with a hybrid fixation technique. We could expect a durable implant in revision TKA with a minimal vertical cementing extents and it was 65mm for the femur and 55mm for the tibia. Level of Evidence. IV, Cases series

Patient function is poorly characterised following revision TKA. Modern semi-constrained implants are suggested to offer high levels of function, however, data is lacking to justify this claim. 52 consecutive aseptic revision TKA procedures performed at a single centre were prospectively evaluated; all were revision of a primary implant to a Triathlon total stabiliser prosthesis. Patients were assessed pre-operatively and at 6, 26, 52 and 104 weeks post-op. Outcome assessments were the Oxford Knee Score (OKS), range of motion, pain rating scale and timed functional assessment battery. Analysis was by repeated measures ANOVA with post-hoc Tukey HSD 95% simultaneous confidence intervals as pairwise comparison. Secondary analysis compared the results of this revision cohort to previously reported primary TKA data, performed by the same surgeons, with identical outcome assessments at equivalent time points. Mean age was 73.23 (SD 10.41) years, 57% were male. Mean time since index surgery was 9.03 (SD 5.6) years. 3 patients were lost to follow-up. All outcome parameters improved significantly over time (p <0.001). Post-hoc analysis demonstrated that all outcomes changed between pre-op, 6 week and 26 weeks post-op assessments. No difference was seen between primary and revision cohorts in OKS (p = 0.2) or pain scores (p=0.19). Range of motion and functional performance was different between groups over the 2 year period (p=0.03), however this was due to differing pre-operative scores, post-hoc analysis showed no difference between groups at any post-operative time point. Patients undergoing aseptic revision TKA with semi-constrained implants made substantial improvements in OKS, pain scores, knee flexion, and timed functional performance, with the outcomes achieved comparable to those of primary TKA. High levels of function can be achieved following revision knee arthroplasty, which may be important considering the changing need for, and demographics of, revision surgery

Aims

Distal femoral resection in conventional total knee arthroplasty (TKA) utilizes an intramedullary guide to determine coronal alignment, commonly planned for 5° of valgus. However, a standard 5° resection angle may contribute to malalignment in patients with variability in the femoral anatomical and mechanical axis angle. The purpose of the study was to leverage deep learning (DL) to measure the femoral mechanical-anatomical axis angle (FMAA) in a heterogeneous cohort.

Revision TKR is a challenging procedure, especially because most of the standard bony and ligamentous landmarks are lost due to the primary implantation. However, as for primary TKR, restoration of the joint line, adequate limb axis correction and ligamentous stability are considered critical for the short- and long-term outcome of revision TKR. There is no available data about the range of tolerable leg alignment after revision TKR. However, it is logical to assume that the same range than after primary TKR might be accepted, that is ± 3° off the neutral alignment. One might also assume that the conventional instruments, which rely on visual or anatomical alignments or intra- or extramedullary rods, are associated with significant higher variation of the leg axis correction. We used an image-free system (ORTHOPILOT TM, AESCULAP, FRG) for routine implantation of primary TKA. The standard software was used for revision TKA. Registration of anatomic and kinematic data was performed with the index implant left in place. The components were then removed. New bone cuts as necessary were performed under the control of the navigation system. The size of the implants and their thickness was chosen after simulation of the residual laxities, and ligament balance was adapted to the simulation results. The system did not allow navigation for centromedullary stem extension and any bone filling which may have been required. This technique was used for 54 patients. The accuracy of implantation was assessed by measuring the limb alignment and orientation of the implants on the post-operative radiographs. Limb alignment was restored in 88%. The coronal orientation of the femoral component was acceptable in 92% of the cases. The coronal orientation of the tibial component was acceptable in 89% of the cases. The sagittal orientation of the tibial component was acceptable in 87% of the cases. Overall, 78% of the implants were oriented satisfactorily for the five criteria. The navigation system enables reaching the implantation objectives for implant position and ligament balance in the large majority of cases, with a rate similar to that obtained for primary TKA. The navigation system is a useful aid for these often difficult operations, where the visual information is often misleading. The navigation system used enables facilitated revision TKA

Introduction. Patients with solid organ transplant have been shown to have increased risk of complications following TKA compared to non-transplant patients. The risk of AKI in KTx is reported to be as high as 15.6 % and associated with increased morbidity, and length of stay (LOS). Our aim was to determine the incidence of AKI in KTx undergoing primary and revision TKA and to identify risk factors for its occurrence and its effect on allograft function 1 year postoperatively. Methods. Using the orthopedic and transplant databases we designed a case-control study of 82 patients undergoing 101 TKA between 2000 and 2018 at our institution. The average age at surgery was 65 years (range 35–83); 58% male and 98% white. AKI was defined per KIDGO guidelines. Results. The incidence of AKI was 7 % after primary and revision TKA. Median baseline kidney function (eGFR) was lower in the AKI group (33 vs. 53 ml/min, p=0.003). All AKI were stage 1 as per AKIN criteria. LOS was 4.9 vs. 3.5 days for those with and without AKI (p= 0.04). There was no significant difference between anesthesia time, pressor requirements, estimated blood loss, transfusion, or amount of fluid administered between the 2 groups. At one year, there was a drop in eGFR in AKI patients compared to non-AKI patients (− 14 vs. 0 ml/min (p=0.042). Discussion. The incidence of AKI after TKA in KTx was 7 % in this cohort and associated with longer hospitalization. AKI occurred in patients with lower baseline eGFR and there were no other identified risk factors. Despite the injury being mild, AKI in KTx was associated with greater decrease in eGFR at 1 year prompting the need to identify patients preoperatively at greatest risk. For figures, tables, or references, please contact authors directly

Introduction. Revision TKA can be a difficult and complex procedure. Bone quality is commonly compromised and stem fixation is required in many cases to provide stability of the prosthetic construct. However, utilization of diaphyseal engaging stems adds complexity to the case and can present technical challenges to the surgeon. Press fit metaphyseal sleeves can provide stable fixation of the construct without the need for stems and allows for biologic ingrowth of the prosthesis. Metaphyseal sleeves simplify the revision procedure by avoiding the need to prepare the diaphysis for stems, alleviating the need for offset stems and decreasing the risk of intra-operative complications. The ability to obtain biologic fixation in the young patient is also appealing. This study reports on the author's mid-term experience with this novel technique. Methods. Between May 2007 and June 2009 the author performed 17 revisions TKA that utilized press-fit metaphyseal sleeves without stems on either the tibial side of the joint, the femoral side of the joint or both. Twenty six sleeves were implanted altogether (13 tibial, 13 femoral). Patients were limited to touch down weight bearing for 6 weeks post-operatively. The patients were followed prospectively with clinical and radiographic follow-up at routine intervals. Results. Average clinical and radiographic F/U for the cohort was 57 months (range 30 – 77). Fourteen of seventeen patients had a minimum of 4 years F/U. Average age at the time of surgery was 58 years (range 46–72) and average BMI was 32.4. Indications for the index revision included nine knees with aseptic loosening and / or osteolysis, two knees for septic loosening, two knees for instability and 4 knees for pain / stiffness or other causes. ROM at pre-op and latest F/U averaged 2–108 deg and 0–117 deg respectively. Knee Society Scores at pre-op and latest F/U averaged 35 and 86 respectively (range 57–100). Survivorship analysis revealed 25 of 26 sleeves (96%) to still be in situ at latest F/U. One tibial sleeve was revised at 30 months for septic loosening. Radiographic analysis revealed 22 of the remaining 25 sleeves (88%) to be ingrown. Two tibial sleeves and one femoral sleeve exhibit stable fibrous fixation and are asymptomatic. Conclusions. Press-fit metaphyseal sleeves utilized without stems appear to provide excellent stability of the revision TKA construct at mid-term F/U. Biologic fixation appears to be present in the majority of cases. This ability to obtain reliable osseointegration of the revision construct is appealing, especially in the younger revision patient. The sleeves have proven easy to use and there have been no intra-operative complications. This technique appears to provide a simple, but robust alternative when compared to revision TKA with stems in appropriate cases. Further F/U of this cohort is necessary to evaluate long term results

Introduction Computer assistance can be valuable in positioning of knee prostheses when the bone interface is in the form of bone graft. The efficacy of this technique can be checked using the Perth CT Protocol for knee prosthesis alignment. Methods Fourteen patients are presented who had an allograft revision total knee replacement. The entire prosthesis had to be removed and this resulted in bone deficits sufficently severe to require bone grafting. The Stryker computer navigation system was used. The final outcome was subsequently checked using a multi-slice CT which provided a six paramenter evaluation of the alignment of the knee prosthesis. Results The technique produces excellent alignment of both components in the coronal plane, less good results in sagittal plane and the greatest problems are in the axial plane with femorotibial mismatch occuring in 50%. The mean mal-alignment index is 4.0:1.4. This compares with an index of 2.6:1.3 in navigated primary TKRs. Conclusions Computer assistance provides significant help in the revision total knee replacement but does not produce perfect alignment in every case. Further refinement of the techniques are still needed

This study evaluated the effect of prosthetic patellar resurfacing on outcome of revision total knee arthroplasty. One hundred and twenty-six patients who underwent consecutive revision of total knee arthroplasty were identified. The status of the patella was ascertained post revision as to the presence or absence of patellar prosthesis. WOMAC, Oxford-12, SF-12 and patient satisfaction data were obtained at a minimum of two years follow-up. Follow-up was obtained in one hundred and ten patients. There was no significant difference between the two cohorts with regards to outcomes. A patellar prosthesis does not appear to significantly affect pain, function, or satisfaction outcomes following revision total knee arthroplasty. The purpose of this study is to evaluate the effect of prosthetic patellar resurfacing on outcome of revision total knee arthroplasty in a matched cohort study. The presence or absence of a patellar prosthesis does not appear to significantly affect pain, function, or satisfaction outcomes following revision total knee arthroplasty. Attempting to resurface the patella in revision cases may not be worthwhile. Follow-up was obtained in one hundred and ten patients (fifty-two with patellar component, fifty-eight bony shell), matched for age, sex and co-morbidity scores and followed for a minimum of two years. There was no significant difference between the two cohorts with regards to outcomes of WOMAC pain (mean seventy-two and sixty-five, p=0.17), WOMAC function (mean sixty-four and fifty-nine, p=0.26) scores, Oxford −12 (mean sixty-three and sixty-seven, p=0.2), SF-12 (mean forty and thirty-six, p=0.27) and satisfaction outcomes (mean eight and nine, p=0.07), (power of 0.8, beta=0.2). From January 1997 to December 1999 one hundred and twenty-six patients who underwent consecutive revision total knee arthroplasty were identified. The status of the patella was ascertained post revision as to the presence or absence of patellar prosthesis. At a minimum of two years follow-up, pain and function were assessed by questionnaire for WOMAC, Oxford-12, SF-12 and patient satisfaction data. Co-morbidity, surgical exposure, HSS knee scores and ROM were also collected. Univariate and multivariate analyses were performed. It is questionable whether patient’s pain, function and satisfaction are affected in revision total knee arthroplasty by patellar prosthetic resurfacing. Funding: One or more of the authors has received funding from a commercial party. This was DePuy, Inc, Warsaw, IN

Introduction: Chronic stiffness is an uncommon complication of total knee arthroplasty (TKA) with reports in the literature citing an incidence of 1–5%. Surgical options to manage this debilitating condition include manipulation under anaesthesia (MUA) and arthrolysis; there is concern regarding revision surgery given the potential for stiffness recurrence. Methods: Patients undergoing revision TKA for stiffness were prospectively identified. Inclusion criteria required a flexion contracture greater than 10 degrees and/or less than 70 degrees arc of motion. WOMAC and SF-36 self-report questionnaires were completed by all patients’ pre and post revision surgery. Results: Between July 2005 and Dec 2006, 7 consecutive, aseptic, primary TKA’s were revised to address limited range of motion. Five female and 2 male patients (mean age: 57.6 years) underwent revision TKA 17.1 months (range, 7–25 months) after index TKA. All patients had attempted MUA, with additional open arthrolysis unsuccessful in 1 case. A medial parapatellar approach was performed although 3 required additional quadriceps snip for exposure. Five cases were revised with the Scorpio TS system and 2 with posterior stabilised components. Femoral augmentation was required in 2 cases and tibial in 1. Gap imbalance with increased soft tissue tension was noted intra-operatively in 5 cases with arthrofibrosis found in the remainder. At 6 months follow-up, arc of motion increased from a mean of 41.3° preoperatively to 81.4° (p=0.001) while mean flexion contracture decreased from 17.4° to 2.1° (p=0.004). Subjective improvement was also demonstrated: mean WOMAC decreased from 46.5 to 22.5 (p=0.023) and SF-36 scores increased by a mean of 35.8 points (p=0.001). Conclusion: When conservative, implant preserving measures fail, revision surgery can be considered a viable option in addressing restricted movement following primary TKA. Aggressive physiotherapy and good patient compliance is required to minimise the recurrence of stiffness

The number of revision knee arthroplasties performed is projected to rise dramatically in the coming years. Primary knee arthroplasties are also being performed in younger patients increasing the likelihood of multiple revision procedures. Reconstruction can be challenging with bone stock deficiencies and ligament incompetence. The aim of this study was to present our results of revision total knee arthroplasty using metaphyseal sleeve components to aid reconstruction. Sixty seven patients underwent revision total knee arthroplasty between September 2005 and November 2010 using metaphyseal sleeves. There were thirty one male and thirty six female patients. The indication for revision was aseptic loosening in thirty nine, sepsis in fifteen, malalignment in eight and instability in five patients. Thirty four patients had tibial sleeves, thirty patients had both tibial and femoral sleeves and three patients had femoral sleeves during revision. The patients were followed up for a mean of 32 months (Range 12–60) with outcome data collected prospectively. The mean revised oxford knee scores for the patients improved from 15 (Range 2 to 29) preoperatively to 33 (Range 20 to 45) postoperatively. Mean arc of flexion following revision was 87 degrees (Range 55 to 120). Seventy six percent of patients were satisfied or very satisfied with the result of the revision surgery. There have been no radiographic complications specific to the sleeves and no re-operations. There has been one recurrence of infection in a patient revised for sepsis. This has been managed with suppressive antibiotics due to patient co-morbidities. Metaphyseal sleeves are an effective adjunct in revision knee arthroplasty. We have had good results with their use. To our knowledge no larger series has been presented or published

The aim of this study was to measure the effect of hospital case-volume on the survival of revision total knee arthroplasty (RTKA). A retrospective analysis of Scottish Arthroplasty Project data was performed. The primary outcome was RTKA survival at ten years. The primary explanatory variable was annual hospital case-volume. Kaplan-Meier survival curves were plotted with 95% confidence intervals (CI) to determine the lifespan of RTKA. Multivariable Cox proportional hazards were used to estimate relative revision risks over time. From 1998 to 2019, 8894 patients underwent RTKA surgery in Scotland (median age 70 years, median follow-up 6.2 years, 4789 (53.5%) females; 718 (8.8%) for infection). Of these patients, 957 (10.8%) underwent a second revision procedure on their knee. Male sex, younger age at index revision, and positive infection status were associated with need for re-revision. The ten-year survival estimate for RTKA was 87.3% (95%CI 86.5–88.1). Adjusting for gender, age, surgeon volume and infection status, increasing hospital case-volume was significantly associated with lower risk of re-revision (Hazard Ratio 0.78 (0.64–0.94, p<0.001)). The risk of re-revision steadily declined in centres performing >20 cases per year: relative risk reduction 16% with >20 cases; 22% with >30 cases; and 28% with >40 cases. The majority of RTKA in Scotland survive up to ten years. Increasing yearly hospital case-volume above 20 cases is independently associated with a significant risk reduction of re-revision. Development of high-volume tertiary centres may lead to an improvement in the overall survival of RTKA

Aims

Periprosthetic joint infection (PJI) occurs in approximately 1% to 2% of total knee arthroplasties (TKA) presenting multiple challenges, such as difficulty in diagnosis, technical complexity, and financial costs. Two-stage exchange is the gold standard for treating PJI but emerging evidence suggests 'two-in-one' single-stage revision as an alternative, delivering comparable outcomes, reduced morbidity, and cost-effectiveness. This study investigates five-year results of modified single-stage revision for treatment of PJI following TKA with bone loss.

Introduction: Management of bone loss during revision total knee arthroplasty (TKA) can be challenging. The degree and location of bone loss often dictates the type of prosthesis that can be utilized during revision surgery. The aim of this prospective study was to determine if plain radiographs are adequate in assessing the degree of bone loss around TKA and identify the limitations of plain radiographs for this purpose, if any. Methods: 205 patients undergoing revision TKA at our institution were included. The indication for revision was aseptic failure in 120 patients and septic failure in the remaining patients. The plain radiographs were evaluated by a research fellow and the attending surgeon. The degree and the location of bone loss around the TKA was determined using the UPenn Bone Loss chart. The degree of real bone loss was then determined intraoperatively. Results: The predicted amount of bone loss for the tibia based on the AP (p=0.136) and lateral (p=0.702) radiographs correlated well with the intraoperative findings. However, plain radio-graphs underestimated the degree of bone loss around femur, particularly the condyles (p=0.005). Discussion: Reconstructive surgeons performing revision TKA need to be aware of the limitations of routine radiographs in assessing the degree of bone loss around the femoral component. Hence, patients undergoing revision TKA with suspected bone loss may need to be evaluated by additional imaging techniques and/or alternative reconstructive options need to be available to deal with greater than expected degree of bone loss intraoperatively

Introduction. Previous fluoroscopy studies have been conducted on numerous primary-type TKA, but minimal in vivo data has been documented for subjects implanted with revision TKA. If a subject requires a revision TKA, most often the ligament structures at the knee are compromised and stability of the joint is of great concern. In this present study, subjects implanted with a fixed or mobile bearing TC3 TKA are analyzed to determine if either provides the patient with a significant kinematic advantage. Methods. Ten subjects are analyzed implanted with fixed bearing PFC TC3 TKA and 10 subjects with a mobile bearing PFC TC3 TKA. Each subject underwent a fluoroscopic analysis during four weight bearing activities: deep knee bend (DKB), chair rise, gait, and stair descent. Fluoroscopic images were taken in the sagittal plane at 10 degree increments for the DKB, 30 degree increments for chair rise, and at heel strike, toe off, 33% and 66% cycle gait and stair descent. Results. The average weight bearing maximum flexion for the fixed bearing TKA group was 104 degrees (SD = 18.2 degrees). The average medial and lateral anterior-posterior (AP) translation for these subjects from full extension to maximum weight-bearing flexion was −6.74 mm and −8.0 mm in the posterior direction, respectively. The average femorotibial axial rotation was 1.27 degrees from full extension to maximum flexion. The average medial and lateral AP translations respectively from full extension to maximum flexion are shown in Figures 1 and 2 and the corresponding average femorotibial axial rotation pattern is shown in Figure 3. Subjects implanted with a mobile bearing device are presently being analyzed. Discussion. The fixed bearing device, on average, does not allow for much axial rotation when compared to less constrained or mobile bearing TKA designs. Previous studies have mobile bearing rotating platform primary posterior stabilized devices have documented that the bearing does rotate with the femur. Therefore, it is assumed subjects having a mobile bearing TC3 TKA may achieve greater axial rotation. Subjects having the fixed bearing TC3 TKA did achieve posterior femoral rollback of both condyles, revealing that a fixed bearing revision TKA may act more like a hinged device

Aims. The aim of this study was to compare the outcome of revision total knee arthroplasty (TKA) with and without proximalisation of the tibial tubercle in patients with a failed primary TKA who have pseudo patella baja. Patients and Methods. All revision TKAs, performed between January 2008 and November 2013 at a tertiary referral University Orthopaedic Department were retrospectively reviewed. Pseudo patella baja was defined using the modified Insall-Salvati and the Blackburne-Peel ratios. A proximalisation of the tibial tubercle was performed in 13 patients with pseudo patella baja who were matched with a control group of 13 patients for gender, age, height, weight, body mass index, length of surgery and Blackburne-Peel ratio. Outcome was assessed two years post-operatively using the Knee Society Score (KSS). Results. The increase in KSS was significantly higher in the osteotomy group compared with the control group. The outcome was statistically better in patients in whom proximalisation of > 1 cm had been achieved compared with those in whom the proximalisation was < 1 cm. Conclusion. In this retrospective case-control study, a proximal transfer of the tibial tubercle at revision TKA in patients with pseudo patella baja gives good outcomes without major complications. Cite this article: Bone Joint J 2017;99-B:912–16

Abstract. Introduction. Revision total knee arthroplasty (RTKA) is a complex procedure with higher rates of re-revision, complications and mortality compared to primary TKA. We report the effects of the establishment of a Revision Arthroplasty Network (The East Midlands Specialist Orthopaedic Network; EMSON). Methodology. The Revision Arthroplasty Network was established in January 2015 and covered the Nottinghamshire and Lincolnshire areas of England. This comprises a collaborative weekly multidisciplinary meeting where upcoming RTKA procedures are discussed, and a plan agreed. Using the Hospital Episode Statistics database, RTKA procedures carried out between 2011 and 2018 from the five EMSON hospitals were compared to all other hospitals in England. Age, sex, and Hospital Frailty Risk scores were used as covariates. The primary outcome was re-revision surgery within 1 year of the index revision. Secondary outcomes were re-revision surgery within two years, any complication within one and two years and median length of stay. Results. 33,828 RTKA procedures were performed across England; 1,028 (3.0%) were conducted within EMSON. Re-revision rates within 1 year were 11.6% and 7.4% pre- and post-intervention respectively within the network. This compares to a pre-post change from 11.7% to 9.7% for the rest of England. In comparative interrupted time-series analysis, there was a significant immediate improvement in re-revision rates for EMSON hospitals compared to the rest of England at 1 year (p = 0.024) and 2 years (p=0.032). Conclusion. Re-revision rates for RTKA improved significantly at one and two years with the introduction of EMSON, when compared to the rest of England

There has been speculation as to whether the outcome of revision total knee arthroplasty (TKA) is as successful as primary TKA, this study was designed to compare the outcomes of primary and revision TKA in order to address this question. The study collected data prospectively from patients operated upon by one surgeon using one prosthesis design in each group. All patients undergoing revision TKA between 1997 and 2000 were included in the study. 100 consecutive patients undergoing primary TKA between 1997 and 1999 were included in the study. All surgery was performed by the senior author. Patients completed SF-12 and WOMAC questionnaires pre-operatively and at six and twelve months post-operatively. Mean scores were calculated for the different areas within both outcome measures (WOMAC pain, stiffness and function; SF-12 – physical constant score [PCS] and mental constant score [MCS]). The results were entered into a database and analysed using a combination of two way and simple repeated measures analysis of variance (ANOVA) and t-tests. Only if the result of the ANOVA was significant were post-hoc adjusted t-tests performed on the data values. WOMAC scores did not differ between the two groups pre-operatively. Both patient groups showed a significant improvement in WOMAC scores at six months (P< 0.0005). In the primary group the pain and function scores improved significantly between six and twelve months (P=0.0258 and P=0.0019 respectively). This was not the case in revision patients. SF-12 PCS scores were significantly better in the primary patients pre-operatively (P< 0.0005). Both groups showed a significant improvement at six months assessment (P< 0.0005). Neither group demonstrated an improvement between six and twelve months. SF-12 MCS scores did not show any difference between the two groups pre-operatively. No significant change in MCS score occurred during the study in either the primary or revision patients. The SF-12 and WOMAC health questionnaires are valid, reliable and responsive outcome measures. The study has collected data prospectively from patients operated upon by one surgeon using one prosthesis design in each group. These findings support the concept that revision TKA leads to a comparable improvement in patient perceived outcomes of physical parameters as does primary TKA in both generic health outcome measures and disease specific outcome measures

Constrained condylar knee (CCK) prosthesis offers an implant option for complex revision total knee arthroplasties in which stable varus-valgus constraint as well as rotational control is needed for severe bone defect and ligament insufficiency. The aim of this study was to evaluate the clinical and radiological outcome of CCK prosthesis in revision TKA. Fify-one revision TKAs performed using CCK prosthesis between Jan. 1998 and Feb. 2006 were performed. The mean follow-up period was 5 years and 3 months (2 to 9 years) and the interval between initial and revision TKA was 8 years (4 months to 21 years). The mean age was 67 years. Range of motion (ROM), knee society (KS) score, hospital for special surgery (HSS) score, complication rate and failure rate was evaluated. The tibiofemoral angle and radiolucent line was also evaluated on plain radiograph. The mean ROM improved from 81.9° to 102°. The mean KS score improved from 49.3° to 79.7°, and KS function score from 50.3 to 71.0 (P< .001). The mean HSS score improved from 50.7 to 78.7 (P< .001). Tibiofemoral angle improved from valgus 3.1° to valgus 5.6° (P< .001). Radiolucent line more than 2mm was observed around 4 femoral and 4 tibial components. Complications including 1 skin necrosis, 1 tibial tubercle nonunion, 2 infections, 3 periprosthetic fractures and 5 arthrofibrosis were observed. Overall rating was excellent or good in 88% at the last follow up. Revision TKA using CCK prosthesis showed comparable results with other reports in average 5 years follow-up

By 1998, 10 patients had undergone 12 revision total knee arthroplasties at our institute. One patient died three weeks after surgery due to cerebral infarction, leaving 11 knees of nine patients for evaluation. Average follow-up was 4.8 years (1 to 9 years). All components were subjected to revision surgery in five knees, the tibial tray and insert in four knees, and only the insert in two knees. Patients were evaluated with clinical examinations, radiographs, and the Knee Society Clinical Rating System. After revision surgery, the Knee Scores and ROMs were restored to almost the same level as just after the first TKA. Re-revision was performed on two patients, one 103 months and the other 82 months after revision TKA. In those two patients, huge bone loss of the proximal tibial canal was filled with cement without bone graft. The other patients, however whose tibial trays were fixed with cement on adequate grafted bone obtained good results. The femoral components that were not treated with revision surgery despite small flaws or scratches due to wear and tear of the tibial insert did not cause marked wear of the new tibial insert. Conclusion: Bone loss of the proximal tibial canal should be filled with bone graft, not with cement only. Femoral components with small flaws or scratches, and without other ploblems, need not to be treated with revision surgery

Aim: To present the experience of a highly specialized total knee arthroplasty revision center with the use of femoral and tibial components with modular press-fit offset stem extensions. Methods: Intramedullary press-fit offset stem extensions were developed to offer an additional option when doing a revision total knee arthroplasty in the presence of periarticular bone loss. The radiological and clinical results of a cohort of 28 patients that had been previously subjected to a revision total knee arthroplasty utilizing modular press-fit offset stem extensions, were studied. Mean follow-up time of these patients was 3.5 years (range, 2–7 years). The NexGen Legacy Knee System was used in all our patients (25% LCCK, 75% LPS). The use of bone cement was restricted to the femoral and tibial articular surfaces only, without any intramedullary use. Results: Femoral intramedullary fit and fill was measured 87.9% in anteroposterior x-rays and 85.5% in laterals. Tibial intramedullary fit and fill was measured 94.5% in anteroposterior x-rays and 89.9% in laterals. Femoral components were implanted in 6.4 degrees of valgus angle (mean values) and 2.5 degrees of flexion (mean values). Tibial components were implanted in 2.2 degrees of valgus angle (mean values) and 3 degrees of posterior slope (mean values). Knee Society Score was 89.5 points, while Function Score was 84.8. One year post-revision follow-up evaluation revealed 89% satisfaction rate among these patients. Conclusion: The use of these press-fit offset stem extensions, with the best possible intramedullary femoral and tibial fit and fill, offer a very rewarding method and an alternative option to deal with complex reconstructive problems during a revision total knee arthroplasty

Purpose of the study: Revision total knee arthroplasty (rTKA) is becoming a routine procedure. The technical problems are greater than with a first-intention implantation because of the potential malposition of the initial implants, loss of bone stock, and prior ligament injury. It could be hypothesised that as for implantation of a primary TKA, navigation might improve the quality of the implantation. Material and methods: We used the Orthopilot™ (Aesculap, RFA) navigation system for first-intention TKA. The standard software was used for revisions. The acquisition of the anatomic and kinematic data was performed while the initial implants in situ. The implants were then removed. Any bone recuts required were done under navigation control. The size of the implants and their thickness were determined after digital simulation of residual laxity; ligament balance was adapted from this data. The system does not allow navigation for centromedullary stem extensions nor for filling potential bone defects. Sixty patients underwent the procedure. There was a comparative series of 30 patients who underwent manual conventional revision using an instrumentation guided by the centromedullary femoral and tibial stems. The quality of the implantation was determined by measuring the alignment of the limb and the orientation of the implants on the postoperative x-rays. Outcome was analysed with Student’s t test and the chi-square test with p< 0.05 taken as significant. Results: There was a significant improvement in quality of the implantation for all radiographic criteria in the navigation group. Limb alignment was restored in 88% of the navigated cases and 73% of the conventional cases. Similar differences were observed for femoral and tibial implant position on the lateral and AP views. Discussion: The objectives set for implant orientation and ligament balance can be met with the navigation system for the majority of knees, with a rate similar to that achieved with primary implantation. The navigation system is an appreciable aid for these often difficult procedures where visual information can be misleading. Conclusion: The navigation system used here facilitated revision TKA

Recent projections expect the number of revision knee replacements performed to grow from 38,000 in 2005 to 270,000 by the year 2030. 1. Although the results of primary total knee arthroplasty are well documented, with overall implant survivorship at 15 years greater than 95%. 2. the results of revision procedures are not as well known. What if the revision TKR fails and what is the prevalence of failure of revision TKRs, the complications and re-operation rates? There are various studies which has either exclusively dealt with the causes or outcomes of revision with a particular prosthesis and survivorship analysis. The effectiveness of revision total knee replacement must be considered in the light of complications rates which could be either medical, orthopaedic surgery related complications or combination of both. The purpose of this study was to evaluate the prevalence of complications, reoperation rates and outcomes in a single surgeon's series between 1984 and 2008. Ninety nine index revision cases were studied. Incidences of surgical complications were 52.5%. The total reoperation rate was 34.3% whilst single re revision accounted for 19.9% whereas multiple re-revision incidences were 4%. The mean outcome in terms of Knee Society Score, Knee Society Function, and Knee society range of motion was statistically and clinically significant between pre operative and posts operative score at one year and remained consistent with time. These results suggest that modern revision total knee replacement are satisfactory operations and the outcomes perhaps can be improved if relatively simple strategies are followed by focusing these operations to specialized that accumulate enough experience from these demanding surgeries. Overall the results asserts that even in the hands of an experienced surgeon the complications do occur which is usually multi factorial, whilst in the light of complications and reoperation incidence the patients can be counselled thoroughly before the procedure

Background. Revision total knee arthroplasties (rTKA) are performed with increasing frequency due to the increasing numbers of primary arthroplasties, but very little is known regarding the influence of muscle strength impairments on functional limitations in this population. Objectives. The aim of this study was to assess relationship between muscle strength and functional level in patient with rTKA. Design and Methods. Twenty-three patients (8 males, 15 females) were included in the study with mean age 68.4±10 years. Patients performed 3 performance tests (50-Step Walking Test, 10 Meter Walk Test, 30-Second Chair-Stand Test), and one self-report test (HSS) were preferred to assess patients. The maximum isometric muscle strength of quadriceps femoris and hamstring muscles of all the patients was measured using Hand-Held Dynamometer (HHD). Results. While moderate-to-strong significant correlations was found between quadriceps femoris muscle strength and 30- Second Chair-Stand Test (r=0.390, p=0.049), 50-Step Walking Test (r=−0.530, p=0.005), 10 Meter Walk Test (r=−0.587, p=0.002), there were not significant correlation between HSS knee score and all performance-based tests (p>0.05). Also there were not significant correlation between hamstring muscle strength and all other measurement tests (p>0.05). Conclusion. The moderate-to-strong statistical significant correlation between quadriceps femoris muscle strength and functional performance tests suggests that improved postoperative quadriceps strengthening could be important to enhance the potential benefits of rTKA

INTRODUCTION. Porous metal bone fillers are frequently used to manage bony defects encountered in revision total knee arthroplasty (rTKA). Compared to structural graft, porous metal bone fillers have shown significantly lower loosening and failure rates potentially due to osseointegration and increased material strength [1]. The strength of porous metal bone fillers used in lower extremities is frequently assessed using compression/shear/torsion test methods, adapted from spine standards. However, these basic methods may lack clinical relevance, and do not provide any insight on the relationship between patient activity and anticipated prosthesis performance. The goal of this study was to evaluate the response of bone fillers under different activities of daily living, in order to define physiologically relevant worst case biomechanics for component evaluation. METHODS. A bone filler tibial augment is shown in Figure 1. A test construct for tibial augments (half-block each for medial and lateral sides) is shown in Figure 2, along with compatible rTKA components. An additional void in the bone was filled using bone cement. Loading was applied through the tibiofemoral contact patches created on polyethylene tibial insert. Loading was used for two activities of daily living; walking and deep knee bend [2–3]. During walking, the tibiofemoral contact patch on the anterior tibial post gets loaded due to femoral hyperextension with 1.2xbody weight (BW), whereas the medial and lateral condyles get loaded with 3xBW compressive load. For deep knee bend, only the condyles get loaded with 4.34xBW. Compared to walking, 45% higher compressive load magnitude in deep knee bend located further posterior was anticipated to create a larger bending moment and induce higher stress on the half augments. A finite element analysis (FEA) was performed by modeling this test construct with a medium size tibial augment. All components were modeled using linear elastic material properties. All interfaces, including the augment-bone interface (representing full bony ingrowth construct) were modeled using bonded contact. The inferior surface of the bone analogue was constrained. Linear static analyses were performed and peak von mises stress predicted in the tibial augments was compared between activities. RESULTS. Deep knee bend resulted in 31% higher stresses in the tibial augments than for walking. High von mises stresses were mostly predicted at the superior/posterior aspect of the internal side of the augment and in the corners of the cutouts. Figure 3 presents the von mises stresses in the tibial augments for both loading scenarios. DISCUSSION. This study revealed that the 45% increased posterior compressive load associated with deep knee bend is a more significant factor than the moment applied to the post during walking gait for a hyperextended knee, when considering the stress in bone filler augments in revision TKA. The stress in the augments can depend on multiple factors and the proposed FEA method can be used to compare stresses in different porous material bone fillers to determine worst case for assessing its strength