Aim. To examine the effects of total knee arthroplasty on markers of inflammation and endothelial dysfunction, as surrogate markers for enhanced risk of vascular disease or precipitation of acute vascular events post-operatively. Methods. All patients undergoing an elective uncemented total knee arthroplasty at a district general hospital were approached at the pre-assessment clinic. The study was explained and the patients were enrolled into the study following written consent. Venous blood samples were taken pre-operatively, day 1 and day 7 post-operatively. Serum levels of interleukin 6 (IL6), tumour necrosis factor (TNF??, e-selectin, Von willebrand factor (vWF), tissue plasminogen activator (tPA) and soluble CD40 ligand were analysed. Also, real time analysis of the expression of CD40 and CD14/CD42a aggregates on monocytes was carried out using flow cytometry. Patients were excluded from the study if there were signs of either superficial or deep infection. Results. Significant rises were seen with vWF, tPA and sCD40L levels up to day 7 (p= 0.01, 0.00. 0.00 respectively). IL6, e-selectin and TNF? levels were also significantly raised up to day 7 (p= 0.017, 0.031, 0.00). Analysis of the flow cytometry data revealed significant rises in the expression of CD40 (p= 0.006) and CD14/CD42a (P= 0.013) on monocytes over the same time period. Conclusion. Our study strongly suggests that patients undergoing an uncemented total knee arthroplasty provokes the release of vasoactive substances within the vasculature. These changes may explain the increased incidence of venous thrombosis and thromboembolism post-operatively as well as a potential increased risk of arterial thrombosis and sequelae from atherosclerotic plaque rupture

Introduction. Cementless total knee arthroplasty (TKA) implants use an interference fit to achieve fixation, which depends on the difference between the inner dimensions of the implant and outer dimensions of the bone. However, the most optimal interference fit is still unclear. A higher interference fit could lead to a superior fixation, but it could also cause bone abrasion and permanent deformation during implantation. Therefore, this study aims to investigate the effect of increasing the interference fit from 350 µm to 700 µm on the primary stability of cementless tibial implants by measuring micromotions and gaps at the bone-implant interface when subjected to two loading conditions. Methods. Two cementless e.motion® tibial components (Total Knee System, B. Braun) with different interference fit and surface coating were implanted in six pairs of relatively young human cadaver tibias (47–60 years). The Orthoload peak loads of gait (1960N) and squat (1935N) were applied to the specimens with a custom made load applicator (Figure 1A). The micromotions (shear displacement) and opening/closing gaps (normal displacement) were measured with Digital Image Correlation (DIC) in 6 different regions of interest (ROIs - Figure 1B). Two General Linear Mixed Models (GLMMs) were created with micromotions and interfacial gaps as dependent variables, bone quality, loading conditions, ROIs, and interference fit implants as independent variables, and the cadaver specimens as subject variables. Results. No significant difference was found for the micromotions between the two interference fit implants (gait p=0.755, squat p=0.232), nor for interfacial gaps (gait p=0.474, squat p=0.269). In contrast, significant differences were found for the ROIs in the two dependent variables (p < 0.001). The micromotions in the anterior ROIs (AM and AL) showed fewer micromotions for the low interference fit implant (Figure 2). More closing gaps (negative values) were seen for all ROIs (Figure 3), except in AM ROI during squat, which showed opening gaps (positive values). The posterior ROIs (PM and PL) showed more closing than seen in the anterior ROIs (AM and AL) for both loading configurations. Discussion. The results presented here demonstrate that increasing the interference fit from 350 µm to 700 µm does not affect the micromotions at the implant-bone interface of tibial TKA. While micromotions values were all below the threshold for bone ingrowth (40 µm), closing gaps were quite substantial (∼−150 µm). Since cementless e.motion® TKA components with an interference fit of 350 µm had shown a survival rate of 96.2% after 8.3 years postoperatively, interfacial gaps can be expected to be within a threshold value that can guarantee good primary stability. Moreover, increasing the interference fit to 700 µm can be considered a good range for an interference fit. For any figures or tables, please contact the authors directly

Introduction. Cemented total knee arthroplasty (TKA) remains the gold standard with survivorship above 90% at greater than 10 years postoperatively. However, with younger, heavier, more active patients undergoing TKA at an increasing rate, cementless implants have the appeal of potential for improved implant fixation longevity and decreased rates of aseptic loosening. The cementless implants are more expensive than their cemented counterparts such that implant costs may create a barrier to utilization. However, such comparisons fail to consider the unavoidable additional costs of cementing, including the cost of operating room time, cement and cementing accessories. The purpose of this study is to compare the actual cost of cemented and cementless TKA. Methods. The TKA cost calculation included the cost of operative time, implants, cement and cementing accessories. The difference in operative time between cemented and cementless TKA was determined from a previously published study of 100 TKAs performed using a cemented (55) or press fit (45) implant of the same design performed at a single institution by four fellowship trained arthroplasty surgeons. The decision to use cemented or cementless design in these patients was made based on patient bone quality intraoperatively. Operative time was compared between groups using a Student's two-tailed T-test. The cost of operating room time was based on estimates in the recent literature. The cost of cement and cementing accessories was estimated based on publically available market data. The cost of implants was estimated from institutional data for multiple companies. Results. The cost comparison between cemented and cementless total knee arthroplasty is summarized in Table 1. Mean operative time for cemented TKA was 14.3 minutes longer than for cementless TKA (94.7 + 15.2 vs. 80.4 + 15.7, p<0.01). The estimated cost of one minute of operating room time in the literature ranges from $30 to $60. For our analysis, we used an estimate of $36 per minute obtained from a recently published multi-center study. This resulted in an average operating room time cost $3406 for cemented and $2894 for cementless TKA. Antibiotic cement costs an average of $250 per bag and antibiotic-free cement costs an average of $75 per bag. Cement mixing techniques vary across surgeons. Approximately 95% use a vacuum system and 5% use a mixing bowl. The cost of vacuum systems ranges from $80 for an enclosed bowl to $125 for a vacuum system that can be directly connected to a cement gun. The cost of a plastic mixing bowl and spatula is $20. The cost of the disposables from a cement injection kit is $25. The average cost of a primary TKA implant, including femoral, tibial and polyethylene liner components, is $3530 for cemented and $4659 for cementless designs. Patellar resurfacing is not routinely used at our institution and therefore was not included in implant cost. Based on our calculations, the average cost of a cementless TKA is $7553. Using the cheapest cementing technique with 2 bags of plain cement and a manual mixing bowl with spatula, the cost of a cemented TKA $7114. Using the most expensive cementing technique with 2 bags of antibiotic cement and a cement gun compatible vacuum mixer, the cost of a cemented TKA is $7564. Conclusion. Cemented TKA remains the gold standard and still accounts for most procedures. Cementless TKA is increasing in utilization and may decrease the rate of aseptic loosening, especially in the rapidly growing young, active population undergoing TKA. Although cementless implants remain more expensive than cemented implants at most institutions, the actual overall cost of the two procedures is similar if operative time, cement and cementing accessories are considered. For any figures or tables, please contact authors directly

Introduction. Initial stability of cementless total knee arthroplasty (TKA) tibial trays is necessary to facilitate biological fixation. Previous experimental and computational studies describe a dynamic loading micromotion test used to evaluate the initial stability of a design. Experimental tests were focused on cruciate retaining (CR) designs and walking gait loading. A FEA computational study of various constraints and activities found CR designs during walking gait experienced the greatest micromotion. This experimental study is a continuation of testing performed on CR and walking gait to include a PS design and stair descent activity. Methods. The previously described experimental method employed robotic loading informed by a custom computational model of the knee. Different TKA designs were virtually implanted into a specimen specific model of the knee. Activities were simulated using in-vivo loading profiles from instrumented tibia implants. The calculated loads on the tibia were applied in a robotic test. Anatomically designed cementless tibia components were implanted into a bone surrogate. Micromotion of the tray relative to the bone was measured using digital image correlation at 10 locations around the tray. Three PS and three CR samples were dynamically loaded with their respective femur components with force and moment profiles simulating walking gait and stair descent activities. Periods of walking and stair descent cycles were alternated for a total of 2500 walking cycles and 180 stair descent cycles. Micromotion data was collected intermittently throughout the test and the overall 3D motion during a particular cycle calculated. The data was normalized to the maximum micromotion value measured throughout the test. The experimental data was evaluated against previously reported computational finite element model of the micromotion test. Results. The maximum average micromotion was on the CR design during walking gait. The greatest CR micromotion during stair descent was 67% of the maximum. The maximum micromotion in the PS design was 55% of the CR walking maximum and occurred during stair descent. The next highest PS value was 52% during walking. The absolute difference in these values was under 3 µm. The majority of the PS micromotion values around the tray were less than 50% that of the maximum micromotion of the CR design. Discussion. The experimental continuation of this investigation into cementless tray stability aligned with computational results in this model. The computational model predicted the PS tray would have 50% of the micromotion of the CR design, which was close to the experimental test. For CR, the computational rank order for walking and stair descent was also the same in the experimental follow-up. Future work in this investigation will include continued validation of the computational and experimental models, including more designs. Further exploration into accounting for patient and surgical variability should be explored. For any figures or tables, please contact authors directly

Introduction. The addition of hydroxyapatite in cementless total knee arthroplasty is believed to reduce the time for implant fixation and rehabilitation, reduce the incidence of RLLs and provide long lasting implant stability, through improved osseointegration. We report the results of a prospective, randomised controlled single blinded study comparing the post operative pain, biological fixation and clinical outcomes with the LCS Complete Porocoat and the hydroxyapatite-coated, LCS Complete Duofix mobile-bearing knee systems. Methods. Two hundred and four patients for TKA were prospectively recruited into the study between November 2006 and November 2008. Subjects were randomly assigned to receive the LCS Complete Duofix or LCS Complete Porocoat knee systems. Outcomes including VAS pain scores, American Knee Society scores and Oxford knee scores were performed pre-operatively and at 3 months. X-rays were analysed by an independent reviewer for the presence of radiolucent lines. Results. At no time point from immediately post-operatively to 3 months post-operatively was there a statistically significant difference between groups, in terms of reduction in pain, as measured by the VAS pain score (p=0.9575). American Knee Society and Oxford Knee scores showed similar results between groups. In terms of fixation of the prostheses, radiological analysis revealed a statistical difference between the study groups, Odds Ratio 28.17 (3.670, 216.3), with Duofix having fewer radiolucent lines than Porocoat. 25% of the Porocoat tibias were assessed as not fixated at 3 months whereas only 1% of the Duofix tibias were considered not fixated. There was no significant difference in pain between the fixated and not fixated groups (p=0.293). Conclusions. The addition of hydroxyapatite did not make a significant difference in terms of pain or functional outcomes in the early post-operative period, but did reduce the incidence of radiolucent lines. The presence of radiolucent lines was not associated with increased pain

We studied the influence of different femoral alignment systems on blood loss and the need for blood transfusion after total knee arthroplasty. We retrospectively recorded the blood loss in two groups of consecutive patients. The first group consisted of 46 patients in whom the total knee arthroplasty was performed using an intramedullary femoral alignment system and the second group consisted of 45 patients in whom the procedure was performed with the extramedullary system. In the first group, the mean volume of drained blood was 758 milliliters, while in the second group it was 613 milliliters (p< 0.05). More patients in the first group required blood transfusions, but there was no significant difference in the number of blood units transfused per patient. In conclusion, extramedullary femoral alignment instrumentation reduces the blood loss after the cementless total knee arthroplasty

Introduction. The purpose of this study is to evaluate the mid-term results of clinical and radiographic results Hi-tech knee a cementless total knee arthroplasty (Nakashima medical Co. Ltd., Okayama, Japan). This TKA system was developed in Chiba University from 1994. The characteristic of this system are flat on flat CR-TKA and cementless fixation. Contact surface are made of titanium alloy and UHMWPE, which is produced by the direct compression mold manufacturing method. Material and Method. Between May 1998 and May 2005, we performed 53 consecutive primary TKAs for 42 patients. There were 41 women and 1 man with a mean age of 64.4 years (39 to 78 years). The average follow up period was 7 years 8 months (5 years to 12 years). Osteoarthritis knee were 21 knees and rheumatoid arthritis were 32 knees. The mean pre-operative FTA was 181.7 degrees (168 to 203 degrees). The method of the operation went in measured cut technique for all cases. All 53 knees were implanted with a cruciate retaining prosthesis. All comportments, included a patella component, were fixed without cement. Clinical evaluations were performed according to American Knee Society (KS) system, knee score and function score. Results. The mean preoperative and postoperative, at the latest follow up, maximum flexion angles were 104 and 114 degrees, respectively. The KS knee score and function score improved from 47.5 and 38.9 points before surgery to 87.6 and 80.4 points after surgery, respectively. Postoperative alignment FTA average 174.8 degrees. Within follow up period, it maintained good valgus-varus stability. There was no major loosening. Six knees (11%) were observed radiolucent line at medial tibia plateau less than 1mm. No revisions of TKA were required because of loosening or sinking. There was also no problem at patellar component. Conclusions. Hi-Tech knee a cementless TKA system was made for the suitable for a Japanese knee, strong initial fixation in a concept. The patella component is also cementless fixation. Contact surface are made of titanium alloy and UHMWPE of the direct compression mold method, it was able to protect the abrasion of the polyethylene in a stable state, too. The mid-term results of Hi-Tech knee a cementless TKA, not only OA but also RA patient knee, provided almost good results

Aims

The mean age of patients undergoing total knee arthroplasty (TKA) has reduced with time. Younger patients have increased expectations following TKA. Aseptic loosening of the tibial component is the most common cause of failure of TKA in the UK. Interest in cementless TKA has re-emerged due to its encouraging results in the younger patient population. We review a large series of tantalum trabecular metal cementless implants in patients who are at the highest risk of revision surgery.

Introduction

The ideal type of total knee arthroplasty (TKA) prosthesis remains a debatable topic with many different options available. Uncemented TKA has been a viable option due to its decreased operating room (OR) time but also because of its proposed improved long term fixation. Unfortunately, in the past uncemented TKA was associated with increased blood loss. Surgical technique and perioperative treatments have changed since these original studies and tranexamic acid (TXA) has become the gold standard for TKA blood loss management. The objective of this study was to evaluate if there was a difference in hemoglobin and hematocrit change, along with blood loss volume during surgery between cemented and cementless TKA when modern blood loss techniques are utilized

Introduction

Cementless TKA offers the potential for strong fixation through biologic fixation technology as compared to cemented TKA where fixation is achieved through mechanical integration of the cement. Few mid-term results are available for newer cementless TKA designs that have used additive manufacturing (3-D printing) for component design. The purpose of this study is to present minimum 5-year clinical outcomes and implant survivorship of a specific cementless TKA using a novel 3-D printed tibial baseplate.

Introduction

A total knee arthroplasty (TKA) is the standard of care treatment for end-stage osteoarthritis (OA) of the knee. Over the last decade, we have observed a change in TKA patient population to include younger patients. This cohort tends to be more active and thus places more stress on the implanted prothesis. Bone cement has historically been used to establish fixation between the implant and host bone, resulting in two interfaces where loosening may occur. Uncemented fixation methods provide a promising alternative to cemented fixation. While vulnerable during the early post-operative period, cementless implants may be better suited to long-term stability in younger patient cohorts. It is currently unknown whether the surgical technique used to implant the cementless prostheses impacts the longevity of the implant. Two different surgical techniques are commonly used by surgeons and may result in different load distribution across the joint, which will affect bone ingrowth. The overall objective of the study is to assess implant migration and in vivo kinematics following cementless TKA.

Cementless fixation in TKA has been inconsistently adopted since its early use but is increasing due to a number of factors, predominantly related to a demand for improved survivorship in younger patients. Modern biomaterials have demonstrated optimal bone ingrowth and have also contributed to a renewed confidence by surgeons to utilise cementless fixation in TKA. With a modern design and appropriate surgical technique, optimal mechanical stability of new designs have been demonstrated and can build upon the excellent long-term outcomes that have rivaled traditional cemented TKA. Paramount to obtaining successful long-term osseointegration and clinical survivorship with cementless fixation is an awareness of the past failure mechanisms to improve implant modern implant design, and should also guide meticulous surgical technique.

A robust implant design with optimal surgical technique is critical to success when employing cementless fixation in TKA. The tried and true principles of sufficient mechanical stability to minimise micromotion of an osteoconductive implant surface with intimate contact against viable bone are essential to allow osseointegration and long-term survivorship. The surgical techniques and tips for “getting it right” include: 1.) Meticulous planar cuts - Prevention of saw blade deviation (particularly anterior femoral cortex and sclerotic medial tibial plateau), Appropriate tolerances in cutting guides (particularly 4-in-1 femoral cutting guide), Appropriate interference fit for tibial keel/stem, patella planar cut, Perfect planar cut on tibial surface confirmed with “4-corner test”. 2.) Implantation of components to maximise mechanical stability - Intimate implant contact with bone (minimizing gaps), Consider bone slurry to minimise gaps, Prevention of femoral component flexion with impaction, Ensure parallel position of tibial baseplate with tibial cut surface during impaction, Peripheral fixation on tibial baseplate, either screws or pegs, to provide supplemental fixation and stability in titanium tray designs.

Background

In recent years, the use of modern cementless implants in total knee arthroplasty has been increasing in popularity. These implants take advantage of new technologies such as additive manufacturing and potentially provide a promising alternative to cemented implant designs. The purpose of this study was to compare implant migration and tibiofemoral contact kinematics of a cementless primary total knee arthroplasty (TKA) implanted using either a gap balancing (GB) or measured resection (MR) surgical technique.

Introduction

Cementless total knees were historically associated with early failure. These failures, likely associated with implant design, made cemented total knee arthroplasty (TKA) the “gold standard”. Manufacturers have introduced newer uncemented technologies that provide good initial stability and utilize a highly-porous substrates for bony in-growth. Outcome data on these implants has been limited. In addition, these implants typically have a price premium which makes them difficult to use in the setting of cost containment and in at risk 90-day bundles. Our purpose was to compare 90-day outcomes of a new uncemented implant with those of a comparable cemented implant from the same manufacturer. We hypothesized that the implants would have equivalent 90-day clinical and economic outcomes.

INTRODUCTION

Total knee arthroplasty (TKA) is typically performed using cement to secure the prosthesis to bone. There are complications associated with cementing that include intra-operative hypotension, third-body abrasive wear, and loosening at the cement interfaces. A cementless prosthesis using a novel keeled trabecular metal tibial baseplate was developed to eliminate the need for cementing the tibial component in TKA.

This paper reports the clinical outcomes and survivorship of a prospective series of Advantim cementless TKR performed at the RAH between 1993 and 2005. There were 210 knees in 176 patients. All procedures were performed or supervised by a single surgeon.

All patients were followed up at regular intervals, up to 15 years later, with Knee Society Cinical Rating System and X-Rays. No patients were lost to follow-up. The knee rating improved from a median of 47 to 90. The median range of motion was 0–100. At 11 years the survivorship of the tibial component was 95.5% and femur was 93.7%. There were two major revisions and three minor revisions for polyethelene exchange. There was no deep sepsis. There was no knee stiffness requiring arhrolysis or manipulation. No screw osteolysis observed. Advantim was the best perfoming TKR in the AOA registry in 2008 with 0.3 revisions per 100 observed component years.

Few studies suggest that the use of a cemented stem reduces proximal stresses and may result in proximal bone resorption. Aim of our study: Does bone cement affect peri prosthetic bone density? The study was approved by the local ethics committee.

Patient and methods: 30 patients were included in each group based on power analysis. All 60 patients had the same type of knee replacement (Rotaglide rotating platform). Both groups, cemented and uncemented respectively were matched for the variables like mean age (67.2 & 67.33 years), gender (13: 17 males: females), body mass index (30.95, 29.90), average time following surgery (4 and 3.25 years), activity level (UCLA scoring: 6 & 4) and mean T score (osteoporosis index: −0.51 & −0.62). Periprosthetic bone density was measured in five regions of interest in the distal femur and five regions of interest in the proximal tibia. This was performed with Prodigy scanner (Lunar) using ‘orthopedic’ software to eliminate metal related artifacts. The same area was measured on the opposite unoperated knee. The values thus obtained were compared between the cemented and uncemented groups.

Results: There was no statistically significant difference in bone density around proximal tibia, patella and bone density proximal to femoral flange. However, there was some difference between the groups for bone density behind the flange of the femoral component measured in the lateral view, although not strictly significant at the 5% level. In this region of interest, the bone density in the cemented group appears to be less than in the uncemented group (p=0.059).

Conclusion: Use of bone cement do not seem to alter the peri prosthetic bone density contrary to suggestions in a few other studies. While reduction in periprosthetic bone density is noted in both groups, use of bone cement did not affect the results significantly.

Between 1990–92, 59 Primary TKA’s were performed in 55 Patients with a mean follow-up of 9 years (8–10). Mean age at review was 75 years (61–87). Materials and Method: All cementless TKA’s (Whiteside Ortholoc Modular 3). One surgeon (operating or supervising). Intramedullary guides(tibia and femur). Lateral retinacular release. Clinical evaluation according to the Knee Society Scoring System & Knee Society TKA Roentgenographic Evaluation and Scoring System. Median Knee Score 93.5 (41–97). Median Functional Score 77.5 (35–100). Median flexion 100 degrees (80–120). All but one knee came to full extension. No effusions or swellings. Radiolucencies in one TKA only. Discussion: Long term success of TKA’s (cementless or cemented) depends on correct alignment of the implants. Rigidity of fixation is the second most important feature in achieving pain free function in an arthroplasty. Success in this series was due to good alignment of components. Good alignment minimises polyethelene wear. Rigid tibial fixation prevents motion, tilting and malalignment reducing wear.

Purpose: To investigate the effect that gender may have on the RSA defined migration pattern of cemented and uncemented tibial components in total knee arthroplasty (TKA).

Method: 70 patients with primary osteoarthritis of the knee were randomized to receive a Nexgen uncemented Trabecular Metal (TM) monoblock tibial component (n=37; 20 female; mean age=66 years; mean BMI=32) or cemented cobalt chrome modular tibial cmponent (n=33; 19 female; mean age=65 years; mean BMI=33). The same design of posterior stabilized tibial component was used in all cases. Four experienced knee surgeons followed a standardized surgical technique (PCL resection, patella resurfacing, RSA bead placement in poly-ethylene and tibia) and post-operative protocol (CPM as tolerated, no drains, WBAT). Within 4 days of surgery and at 6, 12 and 24 months post-operatively patients underwent bi-planar x-rays. RSA analysis was performed with MB-RSA (MEDIS, Leiden). Results were reported as maximum total point motion, and 6 degrees of freedom translations and rotations. A repeated measure ANOVA was used to test for differences and all statistical analysis was performed using Minitab V.14 (Minitab Inc, State College, PA, USA).

Results: Highly significant differences were seen in the migration patterns in females between the TM and cemented tibial components. Females with the TM implant tended to rotate internally (0.29° vs. −0.16°, p< 0.0001), tilt posteriorly (−0.49° vs. 0.01°, p< 0.0001) and subside (−0.357mm vs. 0.00mm, p< 0.0001) compared with the female subjects with the cemented implant. In the male group, only subsidence was different between the TM and cemented groups (−0.344mm vs. −0.01mm, p< 0.0001).

Conclusion: Uncemented TM implants in females tended to tilt posteriorly, rotate internally and subside. Uncemented implants in males tended only to subside. The increased tilting and rotation detected in females could be due to lower BMD or to mismatching between the shape of the female proximal tibial and the tibial component. These results may have implications for the current use of uncemented implants in females and for future design of uncemented implants for the female population.

Cementless total knee replacement (TKR) is at the present date a controversial topic. Aim of the study was to compare the effect on tibial periprosthetic bone mineral density (BMD) between different implant materials and designs.

During the two-year period between January 2005 and December 2006, we analysed data of 45 patients who underwent consecutively cementless TKR (49 implants) at our Institution for primary osteoarthritis. Data was divided in 2 groups: A) 26 implants with tantalium tibial component (Zimmer NexGen Trabecular Metal^TM Monoblock); B) 23 implants with porous titanium tibial component (Lima MultiGen^TM). Data was comparable per sex, age, BMI, post-op alignment, post-op KSS > 75, absence of major post-op complications. Standard AP x-rays were taken 4 months post-op and 8 years post-op. In order to quantify the reduction of BDM, we determined using ImageJ (an open source software) the Mean Grey Value (MGV) of a specific area on the 4 months- and 8 yrs-postop AP x-rays.

Group A and Group B had an average MGV variation of, respectively, 11.79% and 10.51%; there was no statistically significant difference between the two groups.

Reduction of BMD in a TKR is known to be a biomechanical response to load and it is conditioned by the alignment of the components and their design. Our study shows that the different materials (porous titanium vs. tantalium), in relation to the different implant design, have a similar effect on the surrounding bone. The overall results show a valid osseointegration in both group of patients.