Joint registries suggest a downward trend in the use of uncemented Total Knee Replacements (TKR) since 2003, largely related to reports of early failures of uncemented tibial and patella components. Advancements in uncemented design such as trabecular metal may improve outcomes, but there is a scarcity of high-quality data from randomised trials. 319 patients <75 years of age were randomised to either cemented or uncemented TKR implanted using computer navigation. Patellae were resurfaced in all patients. Patient outcome scores, re-operations and radiographic analysis of radiolucent lines were compared. Two year follow up was available for 287 patients (144 cemented vs 143 uncemented). There was no difference in operative time between groups, 73.7 v 71.1 mins (p= 0.08). There were no statistical differences in outcome scores at 2 years, Oxford knee score 42.5 vs 41.8 (p=0.35), International Knee Society 84.6 vs 84.0 (p=0.76), Forgotten Joint Score 66.7 vs 66.4 (p=0.91). There were two revisions, both for infection one in each group (0.33%). 13 cemented and 8 uncemented knees underwent re-operation, the majority of these being manipulation under anaesthetic (85.7%), with no difference (8.3% vs 5.3%, 95% CI -2.81% to 8.89%, p = 0.31). No difference was found in radiographic analysis at 2 years, 1 lucent line was seen in the cemented group and 3 in the uncemented group (0.67% v 2.09%, 95%CI -4.1% to 1.24%, p = 0.29). We found no difference in clinical or radiographic outcomes between cemented and uncemented TKR including routine patella resurfacing at two years. Early results suggest there is no difference between cemented and uncemented TKR at 2 years with reference to survivorship, patient outcomes and radiological parameters

Our objective was to examine revision rates and patient reported outcome scores (PROMS) for cemented and uncemented primary total knee joint replacement (TKJR) at six months, one year and five years post-operatively. Patients and Methods: This matched cohort study involved secondary analyses of data collected as part of a large prospective observational study monitoring outcomes following knee replacement in Christchurch, New Zealand. Cemented and uncemented TKJR participants (n = 1526) were matched on age (± 5 years), sex and body mass index (BMI). From this larger sample, PROMS data, Oxford Knee Score and the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), out to five years post-operatively were analysed for a matched subset of participants (n = 252). The average age of participants was 67.9 years (SD 9.4, range 38-94). There were no differences between cemented and uncemented cohorts on the basis of age, sex, BMI or comorbidities, revision rates or PROMS outcomes. Cemented procedures had greater skin to skin times than uncemented procedures (p < 0.01). Unadjusted outcomes comparing risk for revision across the two participant cohorts did not significantly differ. Overall rates for revision were low (cemented 3.2% v uncemented 2.7%, p=0.70). Propensity adjusted associations between baseline characteristics (age, sex, BMI, comorbidity, baseline Oxford and baseline WOMAC scores) also revealed no differences in risk for revision at any post-operative timepoint. In this large multi-surgeon matched cohort study there were no significant differences in functional outcomes or revision rates, when outcomes following modern cemented and uncemented TKJR were compared out to 5-year follow up. Based on our findings, uncemented TKJR is predictable irrespective of patient's age, BMI or gender

Source of the study: University of Auckland, Auckland, New Zealand. Unicompartmental knee arthroplasty (UKA) is effective for patients with isolated compartment osteoarthritis, however the procedure has higher revision rates. Long-term survivorship and accurate characterisation of revision reasons are limited by a lack of long-term data and standardised revision definitions. We aimed to identify survivorship, risk factors and revision reasons in a large UKA cohort with up to 20 years follow-up. Patient, implant and revision details were recorded through clinical and radiological review for 2,137 consecutive patients undergoing primary medial UKA across Auckland, Canterbury, Counties Manukau and Waitematā DHB between 2000 and 2017. Revision reasons were determined from review of clinical, laboratory, and radiological records for each patient using a standardised protocol. To ensure complete follow-up data was cross-referenced with the New Zealand Joint Registry to identify patients undergoing subsequent revision outside the hospitals. Implant survival, revision risk and revision reasons were analysed using Cox proportional-hazards and competing risk analyses. Implant survivorship at 15 years was comparable for cemented fixed-bearing (cemFB; 91%) and uncemented mobile-bearing (uncemMB; 91%), but lower for cemented mobile-bearing (cemMB; 80%) implants. There was higher incidence of aseptic loosening with cemented implants (3–4% vs. 0.4% uncemented, p<0.01), osteoarthritis (OA) progression with cemMB implants (9% vs. 3% cemFB/uncemMB; p<0.05) and bearing dislocations with uncemMB implants (3% vs. 2% cemMB, p=0.02). Compared with the oldest patients (≥75 years), there was a nearly two-fold increase in risk for those aged 55–64 (hazard ratio 1.9; confidence interval 1.1-3.3, p=0.03). No association was found with gender, BMI or ASA. Cemented mobile-bearing implants and younger age were linked to lower implant survivorship. These were associated with disease progression and bearing dislocations. The use of cemented fixed-bearing and uncemented mobile-bearing designs have superior comparable long-term survivorship

Multiple joint registries have reported better implant survival for patients aged >75 years undergoing total hip arthroplasty (THA) with cemented implant combinations when compared to hybrid or uncemented implant combinations. However, there is considerable variation within these broad implant categories, and it has therefore been suggested that specific implant combinations should be compared. We analysed the most common contemporary uncemented (Corail/Pinnacle), hybrid (Exeter V40/Trident) and cemented (Exeter V40/Exeter X3) implant combinations in the New Zealand Joint Registry (NZJR) for patients aged >75 years. All THAs performed using the selected implants in the NZJR for patients aged >75 years between 1999 and 2018 were included. Demographic data, implant type, and outcome data including implant survival, reason for revision, and post-operative Oxford Hip Scores were obtained from the NZJR, and detailed survival analyses were performed. Primary outcome was revision for any reason. Reason for revision, including femoral or acetabular failure, and time to revision were recorded. 5427 THAs were included. There were 1105 implantations in the uncemented implant combination group, 3040 in the hybrid implant combination group and 1282 in the cemented implant combination group. Patient reported outcomes were comparable across all groups. Revision rates were comparable between the cemented implant combination (0.31 revisions/100 component years) and the hybrid implant combination (0.40 revisions/100 component years) but were statistically significantly higher in the uncemented implant combination (0.80/100 component years). Femoral-sided revisions were significantly greater in the uncemented implant combination group. The cemented implant and hybrid implant combinations provide equivalent survival and functional outcomes in patients aged over 75 years. Caution is advised if considering use of the uncemented implant combination in this age group, predominantly due to a higher risk of femoral sided revisions. The authors recommend comparison of individual implants rather than broad categories of implants

Background. In recent years, ‘Get It Right First Time (GIRFT)’ have advocated cemented replacements in femoral part of Total hip arthroplasty (THA) especially in older patients. However, many studies were unable to show any difference in outcomes and although cemented prostheses may be associated with better short-term pain outcomes there is no clear advantage in the longer term. It is not clear when and why to do cemented instead of cementless. Aim. To assess differences in patient reported outcomes in uncemented THAs based on patient demographics in order to decide when cementless THA can be done safely. Method. Prospective data collection of consecutive 1079 uncemented THAs performed for 954 patients in single trust between 2010 and 2020. Oxford Hip Score (OHS) and complications were analysed against demographic variables (age, sex, BMI, ASA) and prosthesis features (femoral and acetabular size, offset and acetabular screws). Results. The mean pre-operative OHS was 14.6 which improved to 39.0 at 1 year follow up (P Value=0.000). There was no statistically significant difference between OHS outcome in patients aged over 70 versus younger groups. With a small number of revisable complications increase with age from 50s upwards. Male patients’ OHS score was on average 2.4 points higher than women. Men, however were 2.9 times more likely to experience fractures and high offset hips were 2.5 times more likely to experience dislocations. DAIR, intraoperative calcar fractures, post-operative fractures and dislocations were not associated with worse OHS. Patients with increased BMI had worse pre and post-operative hip functions yet, there was a significant multivariate association between increased BMI and increased improvement in OHS from pre-op to 1 year in women aged 55–80 and men under the age of 60. Femoral stem size increases with age but decreases in male patients over 80. There was no difference found in OHS between bilateral hip replacements and unilateral, nor was there any change found with laterality side of the replacement. Conclusions. This study suggests that ageing >70 is not associated with poorer outcomes despite small number of revisable complication rates that increase with age from 50 upwards. Men had marginally higher average OHS than women At 1 year. Higher BMI or ASA scores are associated with worse pre-operative hips and worse final outcome score. Despite this, the Delta OHS increases with increased BMI shown in the 55–80 year old female patients and male patients under 60. Key Words: THR, Uncemented, Oxford hip score, outcome

Gram-negative prosthetic joint infections (GN-PJI) present unique challenges in management due to their distinct pathogenesis of biofilm formation on implant surfaces. To date, there are no animal models that can fully recapitulate how a biofilm is challenged in vivo in the setting of GN-PJI. The purpose of this study is to establish a clinically representative GN-PJI in vivo model that can reliably depict biofilm formation on titanium implant surface. We hypothesized that the biofilm formation on the implant surface would affect the ability of the implant to be osseointegrated. The model was developed using a 3D-printed, medical-grade titanium (Ti-6Al-4V), monoblock, cementless hemiarthroplasty hip implant. This implant was used to replace the femoral head of a Sprague-Dawley rat using a posterior surgical approach. To induce PJI, two bioluminescent Pseudomonas aeruginosa (PA) strains were utilized: a reference strain (PA14-lux) and a mutant strain that is defective in biofilm formation (DflgK-lux). PJI development and biofilm formation was quantitatively assessed in vivo using the in vivo imaging system (IVIS), and in vitro using the viable colony count of the bacterial load on implant surface. Magnetic Resonance Imaging (MRI) was acquired to assess the involvement of periprosthetic tissue in vivo, and the field emission scanning electron microscopy (FE-SEM) of the explanted implants was used to visualize the biofilm formation at the bone-implant interface. The implant stability, as an outcome, was directly assessed by quantifying the osseointegration using microCT scans of the extracted femurs with retained implants in vitro, and indirectly assessed by identifying the gait pattern changes using DigiGaitTM system in vivo. A localized prosthetic infection was reliably established within the hip joint and was followed by IVIS in real-time. There was a quantitative and qualitative difference in the bacterial load and biofilm formation between PA14 and DflgK. This difference in the ability to persist in the model between the two strains was reflected on the gait pattern and implant osseointegration. We developed a novel uncemented hip hemiarthroplasty GN-PJI rat model. This model is clinically representative since animals can bear weight on the implant. PJI was detected by various modalities. In addition, biofilm formation correlated with implant function and stability. In conclusion, the proposed in vivo GN-PJI model will allow for more reliable testing of novel biofilm-targeting therapetics

Introduction. Gram-negative prosthetic joint infections (GN-PJI) present unique challenges in management due to their distinct pathogenesis of biofilm formation on implant surfaces. The purpose of this study is to establish a clinically representative GN-PJI model that can reliably recapitulate biofilm formation on titanium implant surface in vivo. We hypothesized that biofilm formation on an implant surface will affect its ability to osseointegrate. Methods. The model was developed using 3D-printed titanium hip implants, to replace the femoral head of male Sprague-Dawley rats. GN-PJI was induced using two bioluminescent Pseudomonas aeruginosa strains: a reference strain (PA14-lux) and a mutant biofilm-defective strain (ΔflgK-lux). Infection was monitored in real-time using the in vivo imaging system (IVIS) and Magnetic Resonance Imaging (MRI). Bacterial loads on implant surface and in periprosthetic tissues were quantified utilizing viable-colony-count. Field-emission scanning-electron-microscopy of the explanted implants was used to visualize the biofilm formation at the bone-implant-interface. The implant stability, as an outcome, was directly assessed by quantifying the osseointegration in vitro using microCT scan, and indirectly assessed by identifying the gait pattern changes using DigiGait. TM. system in vivo. Results. Localized infection was established within the hip joint and was followed by IVIS in real-time. There was a quantitative and qualitative difference in the bacterial load and biofilm formation between PA14-lux and ΔflgK-lux. This difference in the ability to persist in the model between the two strains was reflected in the gait pattern and implant osseointegration. Conclusions. We developed a novel uncemented hip hemiarthroplasty, GN-PJI rat model. To date, the proposed in vivo biofilm-based model is the most clinically representative for GN-PJI since animals can bear weight on the implant and poor osseointegration correlates with biofilm formation. In addition, localized PJI was detected by various modalities. Clinical Relevance. The proposed in vivo GN-PJI model will allow for more reliable testing of novel biofilm-targeting therapeutics

Introduction:. Studies have demonstrated both clinical and radiological success of reverse shoulder arthroplasty (RTSA), with follow-up approaching 10-years. To date, most RTSA studies involve cemented fixation of the humeral components, and most involving uncemented RTSAs have used implants not necessarily designed for bony ingrowth. Cementless fixation utilizing proximally porous-coated (PPC) femoral implants has shown long term survivorship approaching 99% at greater than 10-years follow-up in total hip arthroplasty. Currently, the number of commercially available PPC RTSA implants is steadily growing, but there has been no published study examining clinical and radiographic outcomes in PPC, press-fit humeral stems. We hypothesized that the clinical and radiographic results of uncemented RTSA utilizing a PPC humeral stem would be similar to cemented RTSA stems when followed for at least 2-years. Methods:. A prospective, IRB approved RTSA outcomes registry with 261 patients that underwent RTSA by one fellowship-trained orthopaedic surgeon between 2005 and 2008 was reviewed. Inclusion criteria were diagnosis of cuff tear arthropathy or severe rotator cuff deficiency refractory to all other treatments, and minimum 2-year clinical and radiographic follow-up. Exclusion criteria were proximal humeral fractures, glenohumeral instability, rheumatoid arthritis, incomplete follow-up, and revision arthroplasty. Outcome measures included active forward elevation (aFE), active external rotation (aER), active internal rotation (aIR), Constant-Murley score (CS), Subjective Shoulder Value (SSV), visual analogue scale (VAS) pain, and American Shoulder and Elbow Surgeons (ASES) score. Radiographs at 2 weeks, 3 months, 1 year, 2 years and yearly thereafter were evaluated for humeral component position, osteolysis, humeral component radiolucent lines (RLLs), stress shielding, and scapular notching. Statistical analysis was conducted by an independent institutional statistician. Results:. The cemented (n = 37) and uncemented (n = 64) cohorts demonstrated comparable age and gender. Average follow-up was 32.4 months in the uncemented group (range 23–52) and 37.0 months in the cemented group (range 23–70). Both cohorts demonstrated significant improvements from preoperative to most recent follow-up in CS, ASES score, SSV, VAS pain, aFE, and aIR (P < 0.05). The cemented cohort showed a significant improvement in aER (P < 0.01), but the uncemented cohort did not (P = 0.14). There was no significant difference when comparing the degree of improvement in any of these values between the cemented and uncemented cohorts (P > 0.05). Radiographically, there was no evidence of humeral component loosening, osteolysis, or component failure observed in either cohort at any time point. There was no significant difference (P = 1.0) in the incidence of humeral component RLLs between the cemented (n = 1) and uncemented (n = 2) cohorts. Stress shielding was observed in 5 uncemented shoulders and 0 cemented shoulders, however this was not significantly different (P = 0.15). There was no significant difference (P = 0.30) in the incidence of scapular notching between the cemented (n = 8) and uncemented (n = 10) cohorts. Conclusion:. Cementless fixation of a porous-coated RTSA humeral stem provides equivalent clinical and radiographic outcomes compared to cemented stems at minimum 2-year follow-up. With advantages such as decreased operative time, no risk of cement-related complications, and ease of revision, cementless fixation may provide several benefits over cemented fixation. Longer-term studies are needed comparing outcomes of cemented versus cementless RTSA

Based on numerous national registries, cemented hip replacements have globally better long-term results than uncemented hip replacements. For example, following data have been published in national registries:. These registries demonstrated clearly that cemented fixation should be definitively preferred than uncemented fixation… Despite this evidence, uncemented fixation is more and more used in the majority of the countries performing total hip replacements. A recent paper analysed the Swedish situation and may give some reasons for explaining this paradox. A Cox proportional hazards model was used to analyze the Relative Risk (RR) of revision for different type of implants and/or fixation for 170,413 total hip arthroplasties. The RR was adjusted for sex, age, and underlying diagnosis. If the RR is lower than 1, less revisions are seen with uncemented fixation and less revisions are seen with cemented fixation when the RR is higher than 1. The figure 1 summarizes the table 6 of this publication. This figure naturally confirms that globally cemented fixation has a lower revision burden with an adjusted RR of 1.5 (revision of any component for aseptic loosening) than uncemented fixation. This difference in the revision is controlled by the cups, where the adjusted RR for uncemented cups is 1.8. Stems demonstrate an opposite behaviour with a lower revision burden for uncemented fixation with an adjusted RR of 0.4. Analysing the revision rate of the 5 most common implants (cemented versus uncemented), the adjusted RR for aseptic loosening is lower than 1 for both cups and stems. The difference of the RR between all cups (RR: 1.8) and the 5 most common cups (RR: 0.5) indicates undeniably that some cup have a major influence on the revision rate of uncemented systems. This analysis allows to draw following conclusions:. •. In national registries, cemented fixation is globally superior. •. The lower clinical results of uncemented fixation seem to be controlled by badly designed uncemented implants. •. Modern uncemented implants have as least equivalent results than cemented implants. •. Based on these results, uncemented fixation will be the key fixation for this century

Total knee replacement (TKR) is an established treatment for end stage joint disease of the knee. Trabecular metal is one of the design experiments seeking to improve the bone-implant interface and wear patterns in order to increase the longevity of primary joint replacements and reduce the revision burden. Uncemented implants retain bone stock, reduce third body wear, and require a shorter operative time. Although only 4% of knee replacements currently being implanted are uncemented TKRs, there has been considerable recent interest in uncemented designs with a hope of improving the survival time of primary implants. National Joint Registry data has been less favourable of uncemented designs thus far. We report our experience with these comparative implants and present our functional and radiological mid-term results. Trabecular metal is made of tantalum. It has an interconnecting 3-dimensional lattice structure which is 80% porous. It closely resembles the microstructural architecture of cancellous bone. Bone grows into the porous structure creating a strong bond between bone and implant. In this design, the tibial pegs are seated in a peripheral position, in denser cancellous bone when compared with a central peg. Tantalum offers an appropriate modulus of elasticity, reducing the likelihood of component lift-off and stress shielding. Over a 4.5 year period, between April 2007 and December 2011, 132 knees in 127 patients with a diagnosis of end stage osteoarthritis, underwent TKR at a single hospital (CMH), performed by a single surgeon (JH). All surgeries were performed with a thigh tourniquet, medial parapatellar approach, antibiotic and VTE prophylaxis, patellar resurfacing, and rapid recovery rehabilitation. 86 cemented TKRs in 78 patients (mean age 76 years), and 66 uncemented TKRs in 49 patients (mean age 68 years). All components were standard NexGen (Zimmer) implants. Follow-up was a mean of 40 months (range 6–87 months). We analysed the patient postoperative routine standing and recumbent anterior-posterior and lateral radiographs using the knee society TKA scoring system. All linear measurements were made using a PACS viewing system and analysed by 2 of the authors independently. There was no significant radiological lucent lines, and no single KSS > 4. Patients completed Oxford Knee Scores and Knee Society Scoring questionnaires to evaluate their functional outcomes. The mean OKS was 41, and KSS 89. In this period there were revisions in 3 cemented prostheses and 2 uncemented prostheses. 2 revisions were for infection, 2 for peri-prosthetic fracture following trauma, and 1 for unexplained pain. The uncemented TKR performs equally as well as its cemented counterpart in our experience, both clinically and radiologically, at mid-term follow-up of up to 7 years (mean 3.3 years)

Background and aim. Recent proposals have been introduced to modify stem design and/or femoral fixation in total hip replacement (THR). New designs need to consider previous design features and their results. The aim of this study has been to evaluate the clinical and radiological results of six different designs of tapered uncemented stems implanted in our Institution. Methods. 1918 uncemented hips were prospectively assessed from 1999 to 2011 (minimum follow-up of five years for the unrevised hips). All hips had a 28 or 32 mm femoral head and metal-on-polyethylene or alumina-on-alumina bearing surface. Six uncemented femoral designs that shared a femoral tapered stem incorporating a coating surface were included in the study. The different design features included the type of coating, metaphyseal filling, and sectional shape. Results. Intra-operative proximal femoral crack was 6.7% in one of the designs (p=0.01), univariate analysis showing a lower risk of crack in the other designs. The position of the stem was neutral in 80% of the cases for all designs. Femoral canal filing was related to the stem design (p<0.001 at the three levels) and to the femoral level assessed (subset alpha=0.005). Twelve stems were revised for aseptic loosening (6 from two different designs). The survival rate for femoral aseptic loosening at 15 years was 96.6% (95% CI 93.8 to 99.4) for one of these two designs ad 97.4% (95% CI95.5 to 99.6) for the other. Regression analysis showed that stem design was the only factor related to aseptic loosening when adjusted for femoral canal filling (at the three levels) stem position (neutral or not) and femoral type (cylindrical or not). Conclusion. Tapered uncemented stems consistently provide excellent bone fixation. New designs need to avoid changing successful features and concentrate on the less successful aspects

Introduction. Long-term success of the cementless acetabular component has been depends on amount of bone ingrowth around porous coated surface of the implant, which is mainly depends on primary stability, i.e. amount of micromotion at the implant-bone interface. The accurate positioning of the uncemented acetabular component and amount of interference fit (press-fit) at the rim of the acetabulum are necessary to reduce the implant-bone micromotion and that can be enhancing the bone ingrowth around the uncemented acetabular component. However, the effect of implant orientations and amount of press-fit on implant-bone micromotion around uncemented acetabular component has been relatively under investigated. The aim of the study is to identify the effect of acetabular component orientation on implant-bone relative micromotion around cementless metallic acetabular component. Materials and Method. Three-dimensional finite element (FE) model of the intact and implanted pelvises were developed using CT-scan data [1]. Five implanted pelvises model, having fixed antiversion angle (25°) and different acetabular inclination angle (30°, 35°, 40°, 45° and 50°), were generated in order to understand the effect of implant orientation on implant-bone micromotion around uncemented metallic acetabular component. The CoCrMo alloy was chosen for the implant material, having 54 mm outer diameter and 48 mm bearing diameter [1]. Heterogeneous cancellous bone material properties were assigned using CT-scan data and power law relationship [1], whereas, the cortical bone was assumed homogeneous and isotropic [1]. In the implanted pelvises models, 1 mm diametric press-fit was simulated between the rim of the implant and surrounding bone. Six nodded surface-to-surface contact elements with coefficient of friction of 0.5 were assigned at the remaining portion of the implant–bone interface [1]. Twenty-one muscle forces and hip-joint forces corresponds to peak hip-joint force of a normal walking cycle (13%) were used for the applied loading condition. Fixed constrained was prescribed at the sacroiliac joint and pubis-symphysis [1]. A submodelling technique was implemented, in order to get more accurate result around implant-bone interface [1]. Results and Discussions. The peak implant-bone sliding interfacial micromotion was observed around 75 microns around superior and supero-posterior regions of the acetabulum, whereas, micromotion was below 50 microns around other regions (area). As compared to other regions, less implant-bone micromotions were observed at the central region of the acetabulum and anterior part of the acetabulum, where micromotions were varied in the range between 5 microns to 30 microns. Although, the generated peak implant-bone sliding micromotion around the uncemented acetabulum was not vary notably due to change in inclination angle of the acetabular component, changes in patterns of implant-bone micromotions were observed and as shown [Fig.1]. Results of the present study indicated that the positioning of the uncemented acetabular component have influence on patterns of implant-bone micromotion and that might have influence on bone ingrowth and long-term success of uncemented acetabular component

The primary stability of an uncemented femoral total knee replacement component is provided by press-fit forces at the bone-implant interface. This press-fit is achieved by resecting the bone slightly larger than the inner dimensions of the implant, resulting in a so-called interference fit. Previous animal studies have shown that an adequate primary stability is required to minimize micromotions at the bone-implant interface to achieve bone-ingrowth, which provides the secondary (long-term) fixation. It is assumed that during implantation a combination of elastic and plastic deformation and abrasion of the bone will occur, but little is known about what happens at the bone-implant interface and how much interference fit eventually is achieved. Purpose of this study was therefore to assess the actual and effective interference fit and the amount of bone damage during implantation of an uncemented femoral knee component. In this study, five cadaveric distal femora were prepared and femoral knee components were implanted by an experienced surgeon. Micro-CT scans and conventional CT-scans were obtained pre- and post-implantation for geometrical measurements and to measure bone mineral density. In addition, the position of the implant with respect to the bone was determined by optical scanning of the reconstructions (Figure.1). By measuring the differences in surface geometry, assessments were made of the cutting error, the actual interference fit, the amount of bone damage, and the effective interference fit. Our analysis showed an average cutting error of 0.67± 0.17 mm, which pointed mostly towards bone under-resections. We found an average actual AP interference fit of 1.48± 0.27 mm, which was close to the nominal value of 1.5 mm. We observed combinations of bone damage and elastic deformation in all bone specimens (Figure. 2), which showed a trend to be related with bone density. Higher bone density tended to lead to lower bone damage and higher elastic deformation (Figure. 3). The results of the current study indicate different factors that interact while implanting an uncemented femoral knee component. This knowledge can be used to fine-tune design criteria of femoral components and obtain adequate primary stability for all patients in a more predictable way

Purpose of study. To investigate possible advantages of uncemented over cemented femoral components in hip resurfacing. Methods. Eighty-seven patients were recruited. Perioperative factors determined cemented or uncemented head utilisation. Minimum follow-up was 24 months. Surgical complications, HHS, periprosthetic radiolucence and femoral neck narrowing were measured. Results. 55 cemented vs. 32 uncemented resurfacings. Cemented group complications: one DVT, one fractured neck of femur. Two patients from this group had periprosthetic radiolucent lines and there was evidence of significant progressive neck narrowing in this group. The uncemented cohort had no complications. Conclusions. There is less femoral neck narrowing in hip resurfacing using uncemented femoral prostheses

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. Uncemented press-fit cups provide bone fixation in primary total hip replacement (THR). However, sometimes screws are needed to achieve primary stability of the socket. We analyzed biomechanical factors related to press-fit in seven cup designs and assessed whether screw use provides similar loosening rates to those of the press-fit technique. Materials y Methods. From a series of 1,350 primary uncemented THRs using seven different press-fit cup designs (a dome loading hemispheric cup and bi- or tri- radius cups), we only analyzed the 889 diagnosed of primary osteoarthritis. All cases were operated by the same surgical team. The use of screws was decided intraoperatively based on cup stability according to the pull-out test. There were 399 female and 490 male patients with a mean age of 65 years old. The mean follow-up was 8.6 years (5–13 years). The reconstruction of the hip rotation center was evaluated according to Ranawat. Results. Screws were required in 223 (25.1%) of the surgeries: 35% of all dome-loaded cups and less frequently with other cup designs (range 18%-24%) (p<0.001) All hips showed good clinical results and radiological bone fixation. Screws were used more frequently in women (p<0.001). Adjusted multivariate analysis revealed that female patients (p<0.001, Odds Ratio (OR): 1.98; 95% Confidence Interval (CI) 1.34–2.95), hips with one of the hemispherical cup designs (p=0.01, OR: 2.51; 95% CI 1.33–5.33) and a greater distance to the rotation hip centre (p<0.001, OR: 1.25; 95% CI 1.15–1.35) had a higher risk for screw use. Every increase of 5 mm in this distance increased the risk of screw use by three (LI=2–4.5). Conclusions. Gender, cup design and reconstruction of the rotation center of the hip determine the primary stability of the cup in uncemented THR. The use of screws, when necessary, provides similar results than the press-fit technique

Statement of purpose. Cement fixation of total knee replacement (TKR) is commonly cited as being the gold standard, with better long-term survival rates when compared to uncemented fixation so the authors set out to analyse the longterm survivorship without aseptic loosening in a series of 471 uncemented TKR. Methods. A consecutive single surgeon series of patients undergoing routine follow up after a hydroxyapatite coated, uncemented and cruciate retaining TKR performed from 1992 to 1995 were analysed. All patients were invited for clinical review and radiological assessment. Revision of the TKR for aseptic loosening was the primary outcome. Secondary outcomes included Knee Society Score (0–200), range of movement, secondary surgical interventions and the presence of polyethylene wear or osteolysis on plain radiography. Results. 471 TKRs were performed in 356 patients (115 bilateral). 432 TKRs were accounted for through follow up. 39 TKRs in 31 pts were lost to follow-up representing 8% who had a mean KSS of 176 at 10 yr f/u. Mean f/u time period was 16.4 yrs (range 15.1–18.5 yrs). Average age at f/u was 81 yrs. 11 TKR had been revised for aseptic loosening. 19 TKRs in 19 patients had had revision of femoral/tibial components for any reason. A further 7 TKRs had undergone polyethylene insert exchange leaving an overall revision rate of 9% or 91% survival without revision. Survivorship without aseptic loosening was 96% (95%CI of 91.9–98.1%) at up to 18 years. A competing risks analysis was undertaken in order to avoid overestimation of survivorship adjusted for the competing risk of death within the study group. This analysis estimated a cumulative risk of revision for aseptic loosening at 18 years of 4.5%. Mean KSS was 176 (SD 21.5). Mean range of movement was 113 degrees of flexion. Conclusion. Uncemented hydroxyapatite coated total knee replacement can achieve favourable long-term survivorship at least as good as that of cemented designs

Introduction. Up to date there are only few reports in literature on the long term survival of uncemented stems. As for cemented THA, 10 year survival of at least 90% is required for any THA. Materials and methods. We followed the first 354 consecutive implantations of an uncemented, straight femoral stem (CLS, Zimmer Inc, Warsaw, USA) in 326 patients. Mean time of follow-up evaluation was 17 years (range, 15-20 years). Results. At follow-up, 84 patients (88 hips) had died, and 12 (12 hips) were lost to follow-up. 34 hips underwent femoral revision: 8 for infection, 8 for periprosthetic fracture, 1 for traumatic loosening and 17 for aseptic loosening of the stem. Overall survival was 89% at 17 years (95%-confidence limits, 87%-92%), survival with femoral revision for aseptic loosening as an end point was 94% at 17 years (95%-confidence limits, 92%-95%). The mean Harris Hip Score at follow-up was 83 points. 220 hips were available for radiolographic evaluation. None of the femoral components showed signs of loosening. Radiolucent lines (<2mm) in Gruen zones 1 and 7 were present in 14.1% (31 hips) and 15.0% (33 hips) respectively. Radiolucencies in zones 2-6 were found in 0.5% (1 hip)-1,8% (4 hips) on ap x-rays. Only one case of distal osteolysis was found after a previous Wagner resurfacing. No case of severe femoral osteolysis was found. The only strong predictor for aseptic loosening was undersizing of the stem with a canal fill index of <75%. Conclusions. The long-term results for this uncemented stem are encouraging and compare favorably with those achieved in primary cemented total hip arthroplasty in this age group

Background and aim. Despite good survivorship analysis for most uncemented tapered straight stems, new proposals modifying stem design in total hip replacement (THR) are being introduced in order to facilitate femoral revision surgery. We have evaluated the clinical and radiological results of four different designs of uncemented tapered straight stems implanted in our institution in order to assess: operative complications, clinical results, survivorship analysis for aseptic loosening and radiographic findings. Methods. 1008 hips implanted from 1998 to 2006 were prospectively followed for a mean of 12 years (range, 10 to 17). Four uncemented femoral designs employing a tapered straight stem were included: 209 Alloclassic stems, 420 Cerafit, 220 SL-Plus and 159 Summit. All hips had a 28 or 32 mm femoral head, and polyethylene (PE)-on metal or ceramic-on-ceramic bearing surface. Radiological femoral type, stem position, femoral canal filling at three levels and the possible appearance of loosening and other bone remodelling changes were recorded in all hips. Results. The rate of intra- and post-operative peri-prosthetic fractures ranged from 0 to 2.5%. No thigh pain was reported in unrevised patients. Among all groups, a total of 15 stems were revised for any cause. The revision rates for any cause at 12 years ranged from 97.1 to 99.3%. (p=0.1). 10 femoral components were revised for aseptic loosening: 6 Alloclassic stems with PE liner sterilized by Nitrogen and 3 SL-Plus stems with standard PE. No revision for aseptic loosening was found in the other designs. The survival rate for stem aseptic loosening was 97.1% (95% CI 95.6–100) for the Alloclassic group at 17 years and 98.2% (95% CI 96.2–100) for the SL-Plus at 14 years. The percentage with a neutral stem position was lower in the Alloclassic and SL-Plus groups (p=0.04). We found that femoral canal filling depended on stem group and stem position at three levels A, B and C (p<0.001). Femoral canal filling was greater in the SL-Plus group at three levels than the others (p<0.001). Bone remodelling changes were more frequent in the SL-Plus group, radiolucent lines (p<0.001) and cortical hypertrophy (p<0.001). Conclusion. Uncemented tapered straight stems consistently provide excellent clinical outcome and bone fixation. Newer proposals must consider these results, avoiding changing successful characteristics and concentrate on improving the less successful aspects

An attempt to analyse whether impaction allografting without cement is more or less satisfactory than the technique with the addition of cement is compromised by conflicting reports of where the migration actually occurs. In some cemented series distal migration of the prosthesis within the cement mantle has been recorded as well as migration of the whole cement/prosthesis construct into the graft. Two prospective consecutive series of revision hip arthroplasties by a single surgeon:- Group 1; Uncemented impaction grafting revision hip replacement in a series of 30 patients (33 hips). Group 2; Cemented impaction grafting revision hip replacement in a series of 30 patients (31 hips). Group demographics were similar. Each case used the same design of hip implant with the only difference in design being a proximal hydroxyapatite coating used on the uncemented implants. Follow-up ranged from 2 to 17 years for the uncemented group and from 1 to 11 years for the cemented group. A validated hip scoring system was employed at regular follow up incorporating pain and functional assessment. Migration rates for the uncemented group were 0 to 15 mm for 30 hips; however 3 hips were revised early due to excessive migration. 3 hips sustained early complications (1 fracture, 1 dislocation, 1 varus malposition of stem). Migration rates for the cemented group were 0 to 9 mm for 29 hips, however the remaining 3 hips were revised due to excessive migration (up to 33mm). Although similar results were obtained in terms of success and also pain and function scores, marginal improvement in results did occur with the cemented series overall. Statistical significance was not reached however. More sinkage occurred in the uncemented group overall, the majority occurring in the first 6 post-operative months. Part of the improvement with the cemented series results may be explained by the improved techniques achieved whilst performing the uncemented series. These results from a single surgeon demonstrate that the method is highly technique dependent and relies on adequate graft impaction. With sufficient graft and an appropriate prosthetic design, cement is not essential to the early success of this method. However, the extent of the initial migration did not accurately predict a successful outcome for the procedure. The absence of cement removes any confusion as to the location of any migration