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

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

Aim. Evaluate the metabolites composition of the synovial fluid from patients with PJI or aseptic failure of total knee arthroplasties. Method. The synovial fluids from 21 patients scheduled for revision total knee arthroplasty (11 with the diagnosis of PJI and 10 with aseptic failures) were analyzed using 1D 1H NMR spectroscopy. Univariate and multivariate statistical analyses were used to identify metabolites that were differentially abundant between those groups. Results. A total of 28 metabolites were identified and five of them found to be differentially abundant between infected and non-infected synovial fluids. Lactate, acetate and 3-hydroxybutyrate were found to be in a higher concentration, and glucose and creatine were found reduced in the synovial fluid from PJI patients. Conclusions. Synovial fluid from patients with PJI exhibit a distinct metabolic profile, possibly reflecting metabolic adaptation that occurs in the infected periprosthetic microenvironment. Further research and studies are warranted to gain a broader insight into the metabolic pathways engaged by both pathogen and immune cells in the context of a PJI

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

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

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. 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

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

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

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

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

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

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. 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

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

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

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

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