Posterior Cruciate-Retaining vs Posterior Cruciate-Stabilized Prosthesis in Total Knee Arthroplasty: A Meta-Analysis.

Objective: To evaluate the clinical and imaging results of posterior cruciate-retaining vs the posterior cruciate-stabilized method in total knee arthroplasty (TKA). Methods: PubMed, EMbase and Cochrane Library databases were used to retrieve randomized controlled trials (RCTs) concerning the posterior cruciate-retaining vs posterior cruciate-stabilized method in TKA. Determination of study quality and data extraction were performed by 2 reviewers. Study heterogeneity was assessed by ReviewManager (RevMan) software and meta-analysis was conducted. Results: A total of 15 RCTs were finally included in our meta-analysis. The results showed that no significant differences were found in the American Knee Society Score (AKSS) (MD = 0.13; 95% CI, -0.73 to 1.00), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) (MD = 0.59; 95% CI, 0.00-1.18), knee extension range of motion (MD = 0.10; 95% CI, -0.30 to 0.51)] or posterior tibial slope (MD = -0.09; 95% CI, -0.52-0.33) after surgery between the 2 groups. Compared with the posterior cruciate-retaining prosthesis group, in the posterior cruciate-stabilized prosthesis group the active knee joint range of motion was significantly increased (MD = -6.99; 95% CI, -9.17 to -4.81), knee flexion was significantly increased (MD = -4.22; 95% CI, -6.03 to -2.41) and the mechanical tibial angle was closed to 6° (MD = 0.85; 95% CI, 0.46-1.25). There were no significant differences in residual knee pain (OR = 1.26; 95% CI, 0.57-2.78), infection rate at the surgical site (OR = 0.50, 95% CI, 0.13-1.88) or revision rate (OR = 0.59; 95% CI, 0.15-2.32) between the 2 groups. Funnel plot revealed no significant bias in the included studies. Conclusions: In summary, patients who received a posterior cruciate-stabilized prosthesis had better knee joint active range of motion, knee flexion and mechanical femorotibial angle than patients who received a posterior cruciate-retaining prosthesis. Due to the surgical difficulty involved in a posterior cruciate-retaining prosthesis, junior doctors should choose a posterior cruciate-stabilized prosthesis first, and senior doctors should choose the prosthesis according to the patient's condition and the surgeon's proficiency at performing the surgery in question.

Comparative retrieval analysis of antioxidant polyethylene: bonding of vitamin-E does not reduce in-vivo surface damage.

BACKGROUND: With the Persona® knee system a new polyethylene formulation incorporating vitamin-E which aims to reduce oxidation and maintain wear resistance was introduced. Although in-vitro studies have demonstrated positive effects of the vitamin-E antioxidants on UHMWPE, no retrieval study has looked at polyethylene damage of this system yet. It was the aim to investigate the in-vivo performance of this new design, by comparing it with its predecessor in retrieval analysis. METHODS: 15 NexGen® and 8 Persona® fixed-bearing implants from the same manufacturer (Zimmer Biomet) were retrieved from two knee revision centres. For retrieval analysis, a macroscopic analysis of polyethylene using a peer-reviewed damage grading method was used (Hood-score). The roughness of all articulating metal components was measured using a contact profilometer. The reason(s) for TKA revision were recorded. Statistical analyses (t-test) were performed to investigate differences between the two designs. RESULTS: The mean Hood score for Persona® inserts was 109.3 and for NexGen® 115.1 without significant differences between the two designs. Results from the profilometer revealed that Persona® and NexGen® femoral implants showed an identical mean surface roughness of 0.14 µm. The Persona® tibial tray showed a significantly smoother surface (0.06 µm) compared to the NexGen® (0.2 µm; p < 0.001). Both Hood score and surface roughness were influenced by the reasons for revision (p < 0.01). CONCLUSIONS: The bonding of the antioxidant vitamin-E to the PE chain used in the novel Persona® knee system does not reduce in-vivo surface damage compared to highly crosslinked PE without supplemented vitamin-E used in its predecessor knee system NexGen®. However, the Persona® titanium alloy tibial tray showed a significantly smoother surface in comparison to the NexGen® titanium alloy tibial tray. This study provides first retrieval findings of a novel TKA design and may help to understand how the new Persona® anatomic knee system performs in vivo.

[Efficacy of hydrotherapy versus gym treatment in primary total knee prosthesis due to osteoarthritis: a randomized controlled trial].

BACKGROUND: Physiotherapy is postulated as an effective treatment after total knee arthroplasty (TKA). The objective of the study was to assess the efficacy of hydrotherapy versus gym kinesitherapy during the second phase of treatment in TKA patients, with regard to the improved gait test, pain, stiffness, joint balance, muscle strength and inflammation. METHODS: A controlled and randomized trial was carried out. TKA patients received a first rehabilitative phase (15 60-minutes sessions) at the gym. In the second phase (15 40-minute sessions), one group performed physiotherapy in a gym and another in a swimming pool. Different variables were assessed (basal, after 15 and after 30 ses-sions): functional capacity, pain and stiffness with WOMAC index, joint balance with goniometer; muscle strength with Lovett scale, and result of 6-minute gait test. RESULTS: A total of 115 patients participated, 59 (51.3%) in the gym group and 56 (48.7?%) in the pool group. After the second phase of re-habilitation, higher clinical improvements were observed in the pool group, with statistically significant differences in pain (p?=?0.005), stiffness (p?=?0.010), joint balance (p?=?0.027) and muscle strength (p?=?0.049) in the operated knee, and in the result of the 6-minute gait test (p?=?0.002). CONCLUSIONS: In TKA patients, hydrotherapy during the second phase of rehabilitative treatment was more effective than gym physiother-apy in terms of improved pain, stiffness, joint balance, muscle strength and gait testing.

Modular knee arthrodesis secures limb, mobility, improves quality of life, and leads to high infection control in periprosthetic knee infection, when revision knee arthroplasty is not an option.

INTRODUCTION: This study compared the outcome of knee arthrodesis versus hinged total knee arthroplasty (TKA) in patients suffering from periprosthetic joint infection (PJI). METHODS: 104 patients with PJI were treated using a two-stage exchange of failed TKA. In case of non reconstructable bone loss or loss of extension mechanism, a modular intramedullary arthrodesis nail was used for reimplantation [Knee Arthrodesis Module (KAM); n = 52]. The control group was retrospectively matched treated using a hinged revision TKA [Rotating Hinge Knee (RHK); n = 52]. PJI remission rates, functional outcome (WOMAC; KSS) and quality of life (SF-12), as well as comorbidities and pain were evaluated. RESULTS: Mean age was 72.5 years. Charlson Comorbidity Index was higher in the KAM group (3.3 vs. 2.8). PJI remission rate was 89.4% (88.5% vs. 90.4%, respectively). In case of reinfection, implant retention was mostly possible in the RHK group (7.7%), whereas amputations were mostly performed in the KAM group (9.6%). Significant pain reduction (VAS 7.9-2.8) was achieved in both groups. Walking distance was significantly reduced in the KAM groups versus the RHK group (504 vs. 1064 m). WOMAC and KSS function scores were significantly reduced in the KAM group (25 vs. 40 and 35 vs. 64). Only moderate reduction in quality of life in the KAM group was observed (SF-12 physical: 34 vs. 40; SF-12 mental: 51 vs. 56) respectively. CONCLUSIONS: Arthrodesis using a modular intramedullary nail is an alternative for limb salvage, pain reduction, and preservation of quality of life and everyday mobility, when revision TKA is not an option. This study presents the largest number of case, comparing the outcome after performing an arthrodesis versus hinged TKA after septic failed TKA.

One-stage versus two-stage revision of the infected knee arthroplasty - a randomized multicenter clinical trial study protocol.

BACKGROUND: A two-stage prosthesis exchange procedure has been the gold standard in surgical treatment of the chronically infected knee arthroplasty so far. This includes 2 surgeries/hospitalizations and an interim period of 2-3 months between surgeries with impaired health, functional status and quality of life of the patients. A one-stage exchange procedure holds many obvious advantages compared to the two-stage approach, but outcomes of a one-stage versus two-stage procedures have never been investigated in a randomized clinical trial. The purpose of this study is primarily to investigate time-adjusted differences in functional status of patients after one-stage versus two-stage revision. Secondary, to report time-adjusted differences in quality of life, complications (including re-revisions due to infection) and mortality. METHODS: This study is a pragmatic, multi-center, randomized, non-inferiority trial comparing one-stage versus two-stage revision of the infected knee arthroplasty. Seven Danish hospitals are currently participating in the study, but additional hospitals can enter the study if adhering to protocol. Ninety-six patients will be included prospectively. Follow-up will be with PROM-questionnaires and clinical controls up to 10 years. The patients who are not able to participate in the randomized trial are followed in a parallel cohort study. PROM'S: Oxford Knee Score and EQ5D + EQ5D VAS questionnaires are completed preoperatively and sent out to the study participants at 6 weeks, 3, 6, 9, 12, 18 and 24 months as well as 5 and 10 years postoperatively. In addition a tailor made cost questionnaire on the non-treating hospital resource use, community health and social service use, travel costs, time off work and informal care are sent out. DISCUSSION: If one of the two treatment alternatives is found superior in both domains of quality of life (both knee-specific and generic) and health economics, that treatment should be promoted. Other outcomes will open informed discussions about treatment strategies for periprosthetic knee infections. TRIAL REGISTRATION: The randomized trial is registered on ClinicalTrials.gov with ID NCT03435679 , initial release date January 31, 2018 and the cohort study is registered with ID NCT04427943 , submitted January 8, 2020 and posted June 11, 2020.

Evaluation of Nutritional Status and Correlation with Postoperative Complications in Elderly Patients Submitted to Surgical Treatment of Proximal Femoral Fractures / Avaliação do estado nutricional e correlação com complicações cirúrgicas em pacientes idosos submetidos a tratamento cirúrgico de fratura do fêmur proximal

Abstract Objective This study aims to evaluate and correlate the nutritional status with potential complications during the immediate postoperative period of elderly patients surgically treated for proximal femoral fractures. Methods A prospective, cross-sectional analytical study with a quantitative approach, targeting patients aged 60 years old or more who were admitted to a hospital in Amazonas, Brazil, for surgical treatment of proximal femoral fractures. Surgical complications during the immediate postoperative period and their relationship with the nutritional status of the patient were determined using the mini nutritional assessment (MNA); in addition, the lymphocyte numbers and serum albumin levels were determined and correlated with the length of hospital stay. Results The sample consisted of 19 elderly patients, of both genders, with a mean age of 70.8 years. Most of the subjects (68.4%) were female. Malnutrition was diagnosed in 15.8% of the subjects using the body mass index (BMI) as, an anthropometric variable, and the MNA identified 31.6% of the subjects with malnutrition. Regarding total lymphocyte count, 100% of the sample showed a positive association with malnutrition in varying degrees; using serum albumin level as a parameter, malnutrition was identified in 89.4% of the subjects. Malnourished patients had the highest average length of stay. Surgical complications as surgical site infections occurred in 10.5% of the patients at risk of malnutrition. Conclusion This study revealed a higher rate of postoperative complications in elderly patients diagnosed with malnutrition.

Resumo Objetivo Avaliar e correlacionar o estado nutricional com possíveis complicações no pós-operatório imediato de pacientes submetidos a tratamento cirúrgico de fraturas de fêmur proximal. Métodos Estudo transversal prospectivo analítico e de abordagem quantitativa, tendo como população-alvo pacientes com idade igual ou superior a 60 anos, internados em uma instituição hospitalar no Amazonas, submetidos a tratamento cirúrgico de fraturas de fêmur proximal. Foram avaliadas as complicações cirúrgicas no pós-operatório imediato e sua relação com o estado nutricional através da mini avaliação nutricional (MAN), assim como a mensuração da contagem de linfócitos e albumina e a sua correlação com o tempo de internação. Resultados A amostra foi composta por 19 pacientes idosos, de ambos os sexos, com média de idade de 70,8 anos. A maioria dos pacientes (68,4%) eram do sexo feminino. Por meio da variável antropométrica índice de massa corporal (IMC), identificou-se a presença de desnutrição em 15,8% dos pacientes e, por meio da MAN, de 31,6%. Na avaliação do cálculo da contagem total de linfócitos, 100% da amostra apresentou associação positiva com desnutrição em graus variáveis e, fazendo-se uso da albumina sérica como parâmetro, a desnutrição foi identificada em 89,4%. Os pacientes desnutridos apresentaram a maior média de tempo de internação. As complicações cirúrgicas, por infecções do sítio cirúrgico, ocorreram em 10,5% nos pacientes em risco nutricional. Conclusão Neste estudo, observou-se maior índice de complicações no pós-operatório em idosos diagnosticados com desnutrição.

Modular Tibial Stem Use and Risk of Revision for Aseptic Loosening in Cemented Primary Total Knee Arthroplasty.

BACKGROUND: Modular tibial stem extensions in total knee arthroplasty (TKA) are designed to reduce the risk of aseptic loosening of the tibial base plate. However, these implants add significant cost and an evaluation of their effectiveness in reducing this risk of loosening has not been studied in a large cohort. We sought to evaluate modular tibial stem utilization in primary TKA. METHODS: We conducted a cohort study using our integrated healthcare system's Total Joint Replacement Registry. Patients who underwent cemented primary TKA were identified (2009-2019). Propensity scores were used to 1:1 match patients without to those with a stem extension. Cox proportional-hazards regression was used to evaluate the risk for revision due to aseptic loosening. RESULTS: Ten thousand four hundred seventy six TKA with a modular tibial stem were matched to 10,476 TKA without a tibial stem. Stem utilization associated with a lower risk of revision for loosening across all postoperative follow-up (hazard ratio = 0.38, 95% confidence interval = 0.17-0.85). CONCLUSION: In a matched cohort study, we observed presence of a stem extension was associated with a lower risk of revision for aseptic loosening. Further study to identify specific risk factors for aseptic loosening and confirm the findings presented here are warranted. LEVEL OF EVIDENCE: Level III.

Is EDTA Irrigation Effective in Reducing Bacterial Infection in a Rat Model of Contaminated Intra-articular Knee Implants?

BACKGROUND: To mitigate the possibility of infection after arthroplasty, intraoperative irrigation is essential to remove contaminating bacteria. Previous studies have demonstrated that irrigation with an EDTA solution before wound closure is superior to irrigation with normal saline in removing contaminating bacteria in a rat model of open fractures. However, the effectiveness of an EDTA solution in a model with a contaminated intra-articular implant remains unclear. QUESTIONS/PURPOSES: (1) Does irrigation with an EDTA solution decrease the proportion of culture-positive joints compared with normal saline, benzalkonium chloride, and povidone iodine? (2) Is an EDTA solution toxic to cells resident in joints including chondrocytes, osteoblasts, and synovial fibroblasts? (3) Does irrigation with an EDTA solution have adverse effects including arthrofibrosis and hypocalcemia? METHODS: We first established a model of contaminated intra-articular implants. Female Sprague-Dawley rats (n = 30 for each treatment group) underwent knee arthrotomy and implantation of a femoral intramedullary wire with 1 mm of intra-articular communication. To simulate bacterial contamination, the inserted wire was inoculated with either Staphylococcus aureus or Escherichia coli. After 1 hour, the wound and implant were irrigated with normal saline, benzalkonium chloride, povidone iodine, or an EDTA solution (1 mM). The animals were euthanized 1 week later, and the distal femur, knee capsule, and implanted wire were harvested for bacterial culture using standard techniques. In this study, we used a well-established animal model of an intra-articular implant and inoculated the implant to simulate the clinical setting of intraoperative contamination. The proportion of culture-positive joints in normal saline, benzalkonium chloride, povidone-iodine, and EDTA groups were compared. The viable cell numbers (chondrocytes, osteoblasts, and synovial fibroblasts) were counted and compared after treatment with either solution. Measurement of blood calcium level and histological examination of the joint were performed to rule out hypocalcemia and arthrofibrosis after EDTA irrigation. RESULTS: With S. aureus inoculation, EDTA irrigation resulted in fewer culture-positive joints than normal saline (37% [11 of 30] versus 70% [21 of 30]; p = 0.019), benzalkonium chloride (83% [25 of 30]; p < 0.001), and povidone iodine (83% [25 of 30]; p < 0.001) irrigation. Likewise, infection rates for implant inoculation with E. coli were also lower in the EDTA irrigation group (13% [four of 30]) than in the normal saline (60% [18 of 30]; p < 0.001), benzalkonium chloride (77% [23 of 30]; p < 0.001), and povidone iodine (80% [24 of 30]; p < 0.001) groups. Between normal saline control and EDTA, there were no differences in cell viability in chondrocytes (normal saline: 98% ± 18%; EDTA: 105% ± 18%; p = 0.127), osteoblasts (normal saline: 102 ± 19%, EDTA: 103 ± 14%; p = 0.835), and synovial fibroblasts (normal saline: 101% ± 21%, EDTA: 110% ± 13%; p = 0.073). EDTA irrigation did not result in hypocalcemia (before irrigation: 2.21 ± 0.32 mmol/L, after irrigation: 2.23 ± 0.34 mmol/L; p = 0.822); and we observed no arthrofibrosis in 30 histologic samples. CONCLUSIONS: In a rat model of a bacteria-contaminated intra-articular implants, intraoperative irrigation with 1 mmol/L of an EDTA solution was superior to normal saline, 0.03% benzalkonium chloride, and 0.3% povidone iodine in preventing surgical-site infection and caused no adverse effects including death of resident cells, arthrofibrosis, and hypocalcemia. Future studies should seek to replicate our findings in other animal models, perhaps such as dog and goat. CLINICAL RELEVANCE: If other animal models substantiate the efficacy and safety of the EDTA solution, clinical trials would be warranted to determine whether the use of an EDTA irrigation solution might reduce the risk of periprosthetic joint infections in patients compared with traditional irrigation solutions.

Probabilistic chemotherapy in knee and hip replacement infection: the place of linezolid.

Prosthetic joint infection (PJI) can occur with a wide range of microorganisms and clinical features. After replacement surgery of prosthetic joint, prescription of probabilistic broad-spectrum antimicrobial therapy is usual, while awaiting microbial culture results. The aim of our study was to describe the antibiotic susceptibility of microorganisms isolated from hip and knee PJI. The data were collected to determine the best alternative to the usual combination of piperacillin-tazobactam (TZP) or cefotaxime (CTX) and vancomycin (VAN). Based on a French prospective, multicenter study, we analyzed microbiological susceptibility to antibiotics of 183 strains isolated from patients with confirmed hip or knee PJI. In vitro susceptibility was evaluated: TZP+VAN, TZP+linezolid (LZD), CTX+VAN, and CTX+LZD. We also analyzed resistance to different antibiotics commonly used as oral alternatives. Among the 183 patients with PJI, 62 (34%) had a total knee prosthesis, and 121 (66%) a hip prosthesis. The main identified bacteria were Staphylococcus aureus (32.2% of isolates), coagulase-negative staphylococci (27.3%), Enterobacteriaceae (14.2%), and Streptococcus (13.7%). Infections were polymicrobial for 28 (15.3%) patients. All combinations were highly effective: CTX+VAN, CTX+LZD, TZP+VAN, and TZP+LZD (93.4%, 94%, 98.4%, and 98.9% of all cases respectively). Use of LZD instead of VAN in combination with a broad-spectrum beta-lactam covers almost all of the bacteria isolated in PJI. This association should be considered in probabilistic chemotherapy, as it is particularly easy to use (oral administration and no vancomycin monitoring).

Optimization of the empirical antibiotic choice during the treatment of acute prosthetic joint infections: a retrospective analysis of 91 patients.

Background and purpose - The preferred treatment of an acute prosthetic joint infection (PJI) is debridement, antibiotics, irrigation and retention of the prosthesis (DAIR). The antibiotic treatment consists of an empirical and targeted phase. In the empirical phase, intravenous antibiotics are started after surgery before micro-organisms are determined in microbiological cultures. Which empirical antibiotic is used differs between hospitals, partly reflecting geographic differences in susceptibility spectrums. We investigated whether flucloxacillin should remain the antibiotic of choice in our hospital for empiric treatment of acute PJI with DAIR. Patients and methods - We retrospectively analyzed 91 patients treated for PJI with DAIR between 2012 and 2016. The susceptibility of micro-organisms was determined in multiple cultures of periprosthetic tissue and synovial fluid for 3 antibiotics: amoxicillin/clavulanic acid, cefazolin, and flucloxacillin. Results - Positive microbiological cultures from 68 patients were analyzed. Staphylococcus aureus was the predominant pathogen, cultured in half of the patients. In one-third of patients more than 1 micro-organism was found. On a patient level, the data showed that 65% were responsive to flucloxacillin, 76% to amoxicillin/clavulanic acid, and 79% to cefazolin. Interpretation - Flucloxacillin appeared to be a suboptimal choice in our patient population treated with DAIR. We therefore changed our practice to cefazolin as the preferred antibiotic in the empirical treatment of acute PJI with DAIR.

Radiostereometric Analysis Permits In Vivo Measurement of Very Small Levels of Wear in TKA.

BACKGROUND: Revision of TKA as a result of polyethylene wear is decreasing, but long-term wear performance of polyethylene is still a topic of interest to surgeons and device manufacturers seeking to improve longevity. Measuring wear of modern, wear-resistant implants has been described using radiostereometric analysis (RSA). Performing in vivo measurements would establish whether implant retrieval studies are representative of wear in well-performing knees. QUESTIONS/PURPOSES: For a single knee implant system, we sought to determine (1) the linear wear rate using RSA; (2) the association between demographic factors and wear rate; and (3) the association between limb alignment and wear rate. METHODS: A total of 49 patients with a minimum followup of 10 years (median, 12 years; range, 10-20 years) were retrospectively selected. During the examined period, 4082 TKAs were performed of which 2085 were the implant examined in this study. There were 71 of these patients who met the criteria including an available full-leg radiograph postoperatively, and 34 of these patients returned for examination along with 15 additional from a separate RSA study that also met the criteria. All patients received a posterior-stabilized, cobalt-chromium-on-conventional polyethylene total knee implant from a single implant system, which was the most commonly used at our institution at the time. Patients underwent standing RSA examinations from 0° to 120° of flexion at a single time point without the use of marker beads. Linear wear rates (including creep) were measured based on intersections between the femoral component and tibial insert models. Associations between wear and patient age at surgery, sex, height, weight, body mass index, tibial insert size, and limb alignment were examined. RESULTS: Using the maximum linear wear rate from any flexion angle, the lateral rate was 0.047 mm/year (interquartile range [IQR], 0.034-0.066 mm/year) and the medial rate was 0.052 mm/year (IQR, 0.040-0.069 mm/year). Using the median of the linear wear rates across all flexion angles, the lateral rate was 0.027 mm/year (IQR, 0.017-0.046 mm/year) and the medial rate was 0.038 mm/year (IQR, 0.022-0.054 mm/year). This rate for males was 0.049 mm/year medially (IQR, 0.042-0.077 mm/year) and 0.032 mm/year laterally (IQR, 0.026-0.059 mm/year), and for females was 0.027 mm/year medially (0.016-0.039 mm/year) and 0.020 mm/year laterally (IQR, 0.013-0.032 mm/year). The wear rate for males was greater medially (difference = 0.022 mm/year, p < 0.001) and laterally (difference = 0.012 mm/year, p = 0.008). There were associations between greater wear and increasing height (ρ = 0.48, p < 0.001 medially and ρ = 0.30, p = 0.04 laterally), decreasing body mass index (ρ = -0.31, p = 0.03 medially), and greater implant size (ρ = 0.34, p = 0.02 medially). Increasingly varus leg alignment was associated with greater medial wear (ρ = 0.33, p = 0.02). CONCLUSIONS: Greater wear rates were associated with demographic factors and leg alignment. Further RSA wear studies of other modern implant systems would provide complementary information to retrieval studies and valuable data on wear resistance. CLINICAL RELEVANCE: Good wear resistance was demonstrated by well-performing implants in patients at long-term followup with wear magnitudes in agreement with reported values from retrieval studies.

Total knee arthroplasties from the origin to navigation: history, rationale, indications.

Since the early 1970s, total knee arthroplasties have undergone many changes in both their design and their surgical instrumentation. It soon became apparent that to improve prosthesis durability, it was essential to have instruments which allowed them to be fitted reliably and consistently. Despite increasingly sophisticated surgical techniques, preoperative objectives were only met in 75% of cases, which led to the development, in the early 1990s, in Grenoble (France), of computer-assisted orthopaedic surgery for knee prosthesis implantation. In the early 2000s, many navigation systems emerged, some including pre-operative imagery ("CT-based"), others using intra-operative imagery ("fluoroscopy-based"), and yet others with no imagery at all ("imageless"), which soon became the navigation "gold standard". They use an optoelectronic tracker, markers which are fixed solidly to the bones and instruments, and a navigation workstation (computer), with a control system (e.g. pedal). Despite numerous studies demonstrating the benefit of computer navigation in meeting preoperative objectives, such systems have not yet achieved the success they warrant, for various reasons we will be covering in this article. If the latest navigation systems prove to be as effective as the older systems, they should give this type of technology a well-deserved boost.

Prospective Comparison of a Metal-Free Ceramic Total Knee Arthroplasty with an Identical Metal System.

AIMS: The aim of this open-label, prospective, short-term study was to carry out an initial comparison of a completely metal-free ceramic with a geometrically identical metallic arthroplasty over a 1-year follow-up period. METHODS: This study investigates a completely metal-free system using a composite matrix material containing aluminum oxide (Al2O3, BPK-S Integration, Peter Brehm GmbH, Weisendorf, Germany) or zirconium oxide (ZrO2, BPK-S Integration Ceramic, Biolox Delta-CeramTec GmbH, Plochingen, Germany). Eighty patients (40 in each group) received either a completely metal-free ceramic system (matrix of aluminum and zirconium oxide) or an anatomically identical metallic knee system made of a cobalt-chromium alloy. Clinical assessment was performed preoperatively, and during follow-up at 3 and 12 months, using the Knee Society Score, Oxford Knee Score, and EQ-5D-VAS. For radiological evaluation, standard preoperative and postoperative standardized radiographs were taken at the given follow-up visits. RESULTS: The postoperative clinical scores improved significantly at the 3- and 12-month follow-ups, but did not differ statistically between the two groups. The radiologically evaluated mean postoperative mechanical and anatomical axes showed proper alignment within both groups at all times. No revision surgery had to be performed, and no complications or loosening were recorded whatsoever. CONCLUSIONS: To our knowledge, this is the first study comparing a total ceramic metal-free knee system with a geometrically identical metallic TKA (total knee arthroplasty). Longer follow-ups will be required to demonstrate the overall efficiency of this TKR and perhaps to expand its medical indication.

[Bone Cement Adhesion on Ceramic Surfaces - Deactivation of Surfaces and as a Consequence Inefficient Retention of Knee Prostheses Because of Adsorption of Atmospheric Water]. / Haftung von Knochenzement auf keramischen Oberflächen ­ Deaktivierung der Oberfläche als wirksame Retentionsfläche für Knieendoprothesen durch die Adsorption von atmosphärischem Wasser.

AIM: CoCrMo alloys are contraindicated for sufferers from allergy. For these patients, uncemented and cemented prostheses made of non-allergenic titanium alloy are indicated. Knee prostheses machined from that alloy, however, may have poor tribological behaviour, especially in contact to UHMWPE inlays. Therefore, high-strength oxide ceramics may be especially suitable for knee replacement in allergy patients with mobile bearing prostheses. For adhesion to bone cement, the ceramic surface only exhibits mechanical retention spots that are less adequate than those with a textured metal surface. Generating undercuts by corundum blasting is highly efficient for mechanical adhesion to a CoCrMo surface, but is not possible on a ceramic surface, due to the brittleness of ceramics. Lack of retention of bone cement promotes micromotions of the prostheses. As a consequence of micromotions, early aseptic loosening is predictable. Silicoating (silicate and silane layering) of the ceramic surface would allow specific adhesion and hence would result in increased and hydrolytically more stable bonding between the bone cement and the prosthesis surface - thereby preventing early aseptic loosening. Silicoating, however, presupposes a chemically active surface that is not blocked by a layer of chemisorbed molecules, e.g. water. Desorption of this chemisorbed layer is mandatory and can be attained by baking out the surface. METHOD: In order to evaluate the effectiveness of surface activation via thermal treatment by baking out, with subsequent silicoating of the surface, the bond strengths of thermally treated and silicate layered ZPTA samples were compared with thermally treated surfaces that had not been silicoated. In our study of thermal surface treatment for baking out the surface, we focused on the question of whether there is a minimal "critical" temperature Ts for effective desorption of a chemisorbed water layer. The samples were prepared for the traction-adhesive strength test (sequence: ceramic disc, silicate and silane layering, protective lacquer ("PolyMA" layer), bone cement, TiAlV probes for the traction-adhesive strength test) and their traction-adhesive strengths were then measured. RESULTS: The bond strength was measured as a function of temperature for ceramic discs that had been baked out and subsequently silicoated. This was graduated, exhibits with a pronounced increase in the bond strength at a baking temperature of Ts ≈ 350 °C. The observed bond strengths before the step are ≤ 20 MPa and after the step ≥ 30 MPa. CONCLUSION: Silicoating is effective in achieving high bond strength of bone cement on surfaces of oxide ceramics and can also stabilise the long term behaviour of the bond strength, provided the surface has been thermally treated prior to silicoating. Because of the proposed migration of the silicoating layer, micromotions and debonding should be widely reduced or even eliminated.

Single-Dose, Preoperative Vitamin-D Supplementation Decreases Infection in a Mouse Model of Periprosthetic Joint Infection.

BACKGROUND: Despite recent advances, infection remains the most common etiology of arthroplasty failure. Recent work suggests that 25-hydroxyvitamin D (25D) deficiency correlates with the frequency of periprosthetic joint infection (PJI). We endeavored to examine whether 25D3 deficiency leads to increased bacterial burden in vivo in an established mouse model of PJI and, if so, whether this effect can be reversed by preoperative 25D3 supplementation. METHODS: Mice (lys-EGFP) possessing fluorescent neutrophils were fed a vitamin D3-sufficient (n = 20) or deficient (n = 40) diet for 6 weeks. A group of 25D3-deficient mice (n = 20) were "rescued" with 1 intraperitoneal dose of 25D3 at 3 days before surgery. A stainless steel implant was inserted into the knee joint and the joint space was inoculated with bioluminescent Staphylococcus aureus (1 × 10 colony forming units [CFUs]). In vivo imaging was used to monitor bacterial burden and neutrophil infiltration. Blood was drawn to confirm 25D3 levels 3 days before surgery and on postoperative days (PODs) 0 and 14. Mice were killed at POD 21, and CFUs were quantified after culture. Myeloperoxidase (MPO) and ß-N-acetylglucosaminidase (NAG) were assayed to look at neutrophil infiltration and activated tissue macrophage recruitment, respectively. RESULTS: Serum values confirmed 25D3 deficiency and repletion of the 25D3-rescued group. Bacterial bioluminescence and neutrophil fluorescence were significantly greater (p < 0.05) in the 25D3-deficient group. CFU counts from the joint tissue and implant were also significantly greater in this group (p < 0.05). Rescue treatment significantly decreased bacterial burden and neutrophil infiltration (p < 0.05). Compared with the 25D3-sufficient and 25D3-rescued groups, MPO activity was higher (p < 0.02) and NAG activity was lower (p < 0.03) in the 25D3-deficient group. CONCLUSIONS: This study demonstrated in vivo in a mouse model of PJI that (1) 25D3 deficiency results in increased bacterial burden and neutrophil infiltration, and (2) this effect can be reversed with preoperative repletion of 25D3. CLINICAL RELEVANCE: Considering that >65% of patients undergoing arthroplasty have insufficient or low levels of total 25D and that 25D levels can be replenished with ease using a U.S. Food and Drug Administration (FDA)-approved, oral 25D3 product, 25D deficiency may be an important modifiable risk factor in humans undergoing joint replacement.

Clinical results of alumina medial pivot total knee arthroplasty at a minimum follow-up of 10years.

BACKGROUND: The medial pivot total knee prosthesis with alumina ceramic femoral components was introduced to reproduce physiological knee kinematics and reduce polyethylene wear. The five-year clinical outcomes of alumina medial pivot total knee arthroplasties (TKA) have previously been reported. The purpose of this study was to provide the longer-term clinical results at a minimum follow-up of 10years. METHODS: The clinical results of 70 alumina medial pivot TKA in 51 consecutive patients, with a minimum follow-up period of 10years, were evaluated. RESULTS: Mean follow-up was 11.8years (range 10 to 13). Alumina medial pivot TKAs improved the patients' Knee Society knee scores, function scores, and postoperative ranges of motion compared with their pre-operative statuses (P<0.05 for each). Revision surgery was required in one knee due to a postoperative fracture of the tibial plateau after a fall that occurred two years postoperatively. Osteolysis and femoral component loosening was identified in one case after the initial five-year time point of analysis. The survival rate was 99.1% at 10years. CONCLUSIONS: This study demonstrated excellent clinical results for patients receiving the alumina medial pivot prosthesis at a minimum follow-up period of 10years.

Mujer de 83 años con disnea y edemas en miembros inferiores / An 83 year old woman with dyspnoea and oedema of the lower limbs

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Dosis única intravenosa de ácido tranexámico como medida de ahorro transfusional en prótesis total primaria de rodilla / Single intravenous tranexamic acid dose to reduce blood loss in primary total knee replacement

Objetivo. Evaluar la eficacia y seguridad de la administración de una dosis única intravenosa de ácido tranexámico como medida de ahorro transfusional en prótesis total primaria de rodilla. Material y métodos. Estudio observacional prospectivo de la administración de ácido tranexámico en pacientes intervenidos de prótesis total primaria de rodilla desde noviembre de 2013 a febrero de 2015, en los que se utilizó un sistema de recuperación de sangre autóloga. Se incluyeron en el estudio 98 pacientes distribuidos en dos grupos de 49 pacientes según la exposición a la administración de ácido tranexámico. La variable principal del estudio fue el número de pacientes que precisaron autotransfusión del sistema de recuperación de sangre autológa. Resultados. No se registraron pérdidas durante el seguimiento. No hubo diferencias significativas entre ambos grupos con respecto a las variables preoperatorias y hospitalarias. Los valores medios de hemoglobina y hematocrito preoperatorios, a las 24 y 48 h postoperatorias eran similares en ambos grupos. El volumen medio de sangrado en el sistema de recuperación de sangre autóloga y la pérdida media estimada de sangre fue menor en los pacientes a los que se había administrado ácido tranexámico, siendo las diferencias significativas. Ningún paciente del grupo en el que se administró ácido tranexámico precisó autotransfusión sanguínea. No se precisó alotransfusión sanguínea en los pacientes de la cohorte. No se registraron eventos adversos relacionados con la administración del ácido tranexámico. Conclusiones. El uso de una dosis única 15 mg/kg de ATX intravenoso en PTR primaria ha presentado una tasa de no autotransfusión ni alotranfusión sanguínea del 100%, sin aumento en la incidencia de eventos trombóticos. Por ello recomendamos su utilización en este grupo de pacientes, con una indicación que debe ser individualizada, justificar su uso en la historia clínica y precisar del consentimiento informado del paciente. Nivel de evidencia III (AU)

Objective. To evaluate the effectiveness and safety of a single intravenous dose of tranexamic acid in order to reduce blood loss in total knee replacement. Materials and methods. Prospective observational study of the administration of tranexamic acid in patients undergoing primary total knee arthroplasty from November 2013 to February 2015, in which an autologous blood recovery system was used. The study included 98 patients, distributed into two groups of 49 patients according to whether or not they received intravenous tranexamic acid. The primary endpoint was the number of patients requiring autologous transfusion from the recovery system autologous blood recovery system. Results. No drop-outs were recorded during follow-up. There were no significant differences between groups as regards the preoperative and hospital variables. The mean preoperative haemoglobin and haematocrit at 24 and 48 hours postoperatively were similar in both groups. The average volume of bleeding in the autologous blood recovery system and estimated average blood loss was lower in patients who had been administered tranexamic acid, with significant differences. No patients in the group that was administered tranexamic acid required blood autotransfusion. The transfusion rate was zero in the two groups. No adverse events related to the administration of tranexamic acid were recorded. Conclusions. Intravenous administration of tranexamic acid, according to the described protocol, has presented a non-autotransfusion or allo-transfusion rate of 100%, with no increased incidence of thrombotic events. Thus, its use in this group of patients is recommended. The indication should be individualized, its use justified in the patient medical records, and informed consent is mandatory (AU)

Prosthetic joint infection caused by Trueperella bernardiae.

Trueperella bernardiae is a Gram-positive coryneform bacilli which role as human pathogen is unknown because it has been usually considered a contaminant. Furthermore its identification by biochemical test was difficult. We describe a prosthetic joint infection in a women who years ago underwent a total knee replacement with superinfection and necrosis of the patellar tendon as major complications. In the sample of synovial fluid collected grew a gram-positive bacilli which was identified by matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) as T. bernardiae. The patient was treated with ciprofloxacin and currently preserves the prosthesis without signs of infection.

Cost-Effectiveness of Five Commonly Used Prosthesis Brands for Total Knee Replacement in the UK: A Study Using the NJR Dataset.

BACKGROUND: There is a lack of evidence on the effectiveness or cost-effectiveness of alternative brands of prosthesis for total knee replacement (TKR). We compared patient-reported outcomes, revision rates, and costs, and estimated the relative cost-effectiveness of five frequently used cemented brands of unconstrained prostheses with fixed bearings (PFC Sigma, AGC Biomet, Nexgen, Genesis 2, and Triathlon). METHODS: We used data from three national databases for patients who had a TKR between 2003 and 2012, to estimate the effect of prosthesis brand on post-operative quality of life (QOL) (EQ-5D-3L) in 53 126 patients at six months. We compared TKR revision rates by brand over 10 years for 239 945 patients. We used a fully probabilistic Markov model to estimate lifetime costs and quality-adjusted life years (QALYs), incremental cost effectiveness ratios (ICERs), and the probability that each prosthesis brand is the most cost effective at alternative thresholds of willingness-to-pay for a QALY gain. FINDINGS: Revision rates were lowest with the Nexgen and PFC Sigma (2.5% after 10 years in 70-year-old women). Average lifetime costs were lowest with the AGC Biomet (£9 538); mean post-operative QOL was highest with the Nexgen, which was the most cost-effective brand across all patient subgroups. For example, for 70-year-old men and women, the ICERs for the Nexgen compared to the AGC Biomet were £2 300 per QALY. At realistic cost per QALY thresholds (£10 000 to £30 000), the probabilities that the Nexgen is the most cost-effective brand are about 98%. These results were robust to alternative modelling assumptions. CONCLUSIONS: AGC Biomet prostheses are the least costly cemented unconstrained fixed brand for TKR but Nexgen prostheses lead to improved patient outcomes, at low additional cost. These results suggest that Nexgen should be considered as a first choice prosthesis for patients with osteoarthritis who require a TKR.