Outcomes in arthroplasty have 3 general sources of variability: the patient, the prosthesis, and the medical-surgical-rehab. services. There are numerous factors that can contribute to earlier-than-usual clinical failure of a TKA (failure = need for revision). There are intense debates regarding design and material factors. There are technical factors such as misalignment, soft tissue imbalance, and inadequate fixation. The greatest source of variability in the outcome equation is, however, the patient. In cohort studies, the amount and type of patient activity influences the longevity of TKA. Quantitative studies have demonstrated >45-fold variation in the number of steps per day. Semi-quantitative data and survey studies show variability in the types of recreational activities and in the intensity. Age is often used as a surrogate, but BMI has a better correlation with activity than age. There is no formula, however, that can predict the longevity of an arthroplasty in a specific patient. For this reason, activity recommendations following arthroplasty continue to be debated. Which do you prioritise; lifestyle or longevity? More importantly, which does the patient prioritise?

Total hip arthroplasty (THA) is effective, reproducible, and durable in the treatment of hip joint arthritis. While improvements in polyethylene materials have significantly reduced wear rates and osteolysis, aseptic loosening of implants remains one of the leading causes of revision THA. Additionally, fears of dislocation and instability have driven the increase in the utilization of larger diameter femoral heads in primary THA which can lead to increased wear when coupled with a polyethylene articulation. Finally, the increasing number of younger and active patients undergoing THA raises questions with regards to the ability of modern conventional bearings to provide durability and longevity beyond second and third decades following joint implantation. Ceramic-on-ceramic articulations are ideally suited for today's young and high demand patients undergoing primary THA. It has the lowest in-vitro wear properties of any bearing couple and the wear characteristics are further improved by its wettability and lubrication particularly when larger heads are utilised. Additionally, improvements in material properties and prosthesis design have significantly decreased fracture rates and increased the reliability of these implants. Furthermore, reported outcomes and longevity of modern ceramic-on-ceramic THAs in younger patients have all shown excellent survivorship despite patients achieving and maintaining a very high level of activity and function. In short, it is the bearing couple most in tune with current market demands and utilization trends. While registry data and meta-analyses of published literature have failed to show the superiority of ceramic-on-ceramic articulations compared to conventional bearings at 10 years, there is evidence that even highly crosslinked polyethylene (HXPE) is not immune to wear. Selvarajah et al. reported steady, in-vivo wear rates of HXPE exceeding 0.1mm/year threshold in young THA patients with 36mm ceramic ball heads. Additionally, small osteolytic lesions have been observed in hips with HXPE bearings at 12–14 years follow up. Finally, analysis of all controlled randomised studies have shown less osteolysis of ceramic-on-ceramic hips compared to polyethylene articulations. The significance of these lesions are unclear but the question remains: Can HXPE as a bearing be able to provide over 30 years of service needed to outlast patients younger than 60 years?. Concerns with cost, squeaking, and fractures do not make ceramic-on-ceramic bearings suitable for all patients undergoing primary THA. However, in young, healthy and active patients, a modern ceramic- on-ceramic articulation is most likely to provide the lowest wear rates, lowest risk of osteolysis, and greatest chance for life-long durability

Both the patient and the surgeon want hip and knee arthroplasties to last a lifetime. As a result, many patients have been told to defer arthroplasty as long as possible. After arthroplasty, many patients have been advised to limit physical activity. Such management strategies prioritise longevity but compromise lifestyle. Given that the technical aspects of the arthroplasty are satisfactory, modern total hip and knee prostheses have demonstrated remarkable durability. Quantitative studies of patient activity have measured up to 48 million cycles in vivo, with impact, without evidence of loosening, osteolysis, or other impending failure. These data suggest that with current technology, an active lifestyle is compatible with implant longevity

Total hip arthroplasty (THA) is effective, reproducible, and durable in the treatment of hip joint arthritis. While improvements in polyethylene materials have significantly reduced wear rates and osteolysis, aseptic loosening of implants remains one of the leading causes of revision THA. Additionally, fears of dislocation and instability have driven the increase in the utilization of larger diameter femoral heads in primary THA which can lead to increased wear when coupled with a polyethylene articulation. Finally, the increasing number of younger and active patients undergoing THA raises questions with regards to the ability of modern conventional bearings to provide durability and longevity beyond second and third decades following joint implantation. Ceramic-on-ceramic articulations are ideally suited for today's young and high demand patients undergoing primary THA. It has the lowest in-vitro wear properties of any bearing couple and the wear characteristics further improved by its wettability and lubrication particularly when larger heads are utilised. Additionally, improvements in material properties and prosthesis design have significantly decreased fracture rates and increased the reliability of these implants. Furthermore, reported outcomes and longevity of modern ceramic-on-ceramic THAs in younger patients have all shown excellent survivorship despite patients achieving and maintaining a very high level of activity and function. In short, it is the bearing couple most in tune with current market demands and utilization trends. While registry data and meta-analyses of published literature have failed to show the superiority of ceramic-on-ceramic articulations compared to conventional bearings at 10 years, there is evidence that even highly crosslinked polyethylene (HXPE) is not immune to wear. Selvarajah et al. reported steady, in-vivo wear rates of HXPE exceeding 0.1 mm/year threshold in young THA patients with 36 mm ceramic ball heads. Additionally, small osteolytic lesions have been observed in hips with HXPE bearings at 12–14 years follow up. Finally, analysis of all controlled randomised studies have shown less osteolysis of ceramic-on-ceramic hips compared to polyethylene articulations. The significance of these lesions are unclear but the question remains: Can HXPE as a bearing be able to provide over 30 years of service needed to outlast patients younger than 60 years?. Concerns with cost, squeaking, and fractures do not make ceramic-on-ceramic bearings suitable for all patients undergoing primary THA. However, in young, healthy and active patients, a modern ceramic-on-ceramic articulation is most likely to provide the lowest wear rates, lowest risk of osteolysis, and greatest chance for life-long durability

At the present time, there is no bearing in total hip arthroplasty that a surgeon can present to a younger and/or more active patient as being the bearing that will necessarily last them a lifetime. This is the driver to offering alternative bearings (crosslinked polyethylene with either a CoCr or ceramic head, resurfacings, and ceramic-on-ceramic) to patients. Each of these bearings has pros and cons, and none has emerged as the clear victor in the ongoing debate. Ceramic-on-ceramic (CoC) bearings have been available for decades. Earlier generation CoC bearings did encounter problems with rare fractures, however, with a greater understanding and improvement in the material, the fracture incidence has been significantly reduced. However, what has emerged in the past few years is an increasing reporting of significant squeaking. The incidence of squeaking, reported in the literature in various series, has varied from less than 1% to over 20%, depending on the definition used. The primary reasons that ceramic-on-ceramic is not truly the articulation of choice for younger patients are: 1) There is absolutely no evidence that this bearing has a lower revision rate. Data from the Australian joint registry actually shows that at 15 years it has a significantly increased rate of revision (7.2%) compared with using a highly crosslinked liner with either a ceramic (5.1%) or a CoCr (6.3%) head; 2) This bearing is by far the most costly bearing on the market. In 2017 with significant constraints on health care systems across the globe, this is a significant concern; 3) This bearing has unique complications including squeaking and both liner and head fracturing. While ceramic-on-ceramic can be considered a viable alternative bearing in total hip arthroplasty, it can be in no way considered the articulation of longevity for the younger patient

At the present time, there is no bearing in total hip arthroplasty that a surgeon can present to a younger and/or more active patient as being the bearing that will necessarily last them a lifetime. This is the driver to offering alternative bearings (crosslinked polyethylene with either a CoCr or ceramic head, resurfacings, and ceramic-on-ceramic) to patients. Each of these bearings has pros and cons, and none has emerged as the clear victor in the ongoing debate. Ceramic-on-Ceramic (CoC) bearings have been available for decades. Earlier generation CoC bearings did encounter problems with rare fractures, however, with a greater understanding and improvement in the material, the fracture incidence has been significantly reduced. However, what has emerged in the past few years is an increasing reporting of significant squeaking. The incidence of squeaking, reported in the literature in various series, has varied from less than 1% to over 20%, depending on the definition used. The primary reasons that Ceramic-on-Ceramic is not truly the articulation of choice for younger patients are:. 1). There is absolutely no evidence that this bearing has a lower revision rate. Data from the Australian joint registry actually shows that at 15 years it has a significantly increased rate of revision (7.2%) compared with using a highly crosslinked liner with either a ceramic (5.1%) or a CoCr (6.3%) head. 2). This bearing is by far the most costly bearing on the market. In 2017 with significant constraints on health care systems across the globe, this is a significant concern. 3). This bearing has unique complications including squeaking and both liner and head fracturing. While Ceramic-on-Ceramic can be considered a viable alternative bearing in total hip arthroplasty, it can be in no way considered the articulation of longevity for the younger patient

Purpose of the study: Revision total knee arthroplasty with major destruction of bone and ligament tissue raises the problem of choosing between a complex reconstruction with a semi-constrained prosthesis or a much more simple procedure using a hinged prosthesis which transmits all of the stress to the bone anchors. The choice is basically one of longevity of the bony fixation of these constrained prostheses (and the deterioration of the articulated pieces). The present work reports the long-term outcome observed with constrained hinged prosthesis with a cemented press-fit stem implanted for bone tumors where the stress is even greater than for revisions. Material and methods: The series included 32 prostheses implanted in young active subjects (mean age 33 years). A hinged, non-rotating Guepar II revision prosthesis was implanted. The part of the implant corresponding to the reconstruction after tumor resection was custom-made but the part implanted in «healthy» bone (for example the tibial piece in a patient with a femoral tumor) was the same as used for revisions prostheses inserted after loosening. On the healthy side, press-fit quadrangular stems were used, generally adapted to the endosteum by reaming. The prosthesis was fixed by simple mechanical adjustment before cementing, using the French paradox system (JBJS 2003). Before 1993, a metal-polyethylene bearing was used and after 1993 a metal-on-metal bearing without inserts. Results: Among the 32 patients with a malignant tumor, 19 survived, seven with 2–10 years follow-up and 12 with 10–21 years follow-up. For the overall series, there was only one case of osteolysis on a tibial tumor which was revised at 12 years. There was one infection (hematogeneous) at 21 years (antibiotic cement). Prostheses with polyethylene inserts produced laxities or synovitis with 50% requiring synovectomy and insert replacement. There were no cases of synovitis for the metal-on-metal bearings. Two stems (inserted in adolescents) were too thin and had to be changed because of fracture without loosening. Discussion: Prosthesis survival was 88% at ten years (1 osteolysis, 2 fractures on tumor), even for the constrained prostheses, even for young and active subjects. Conclusion: The very good longevity of cemented pressfit stems (and the absence of synovitis and osteolysis with metal-on-metal bearings, and the low rate of infection) should be kept in mind as a possible alternative to very complex and possibly less predictable procedures in the presence of certain very severe loosenings with bone and ligament destruction

Total Knee Arthroplasty has proven to be a successful procedure for improving pain and function. Long-term studies have shown survivorship to be 90% or greater at 20 years. Most patients in those studies were over 60 years old. There has been a large increase in patients under 60 years old who are undergoing knee arthroplasty. Younger patients have much greater demands on the artificial articular surfaces. The average 55 year old is likely to perform two to three time as many gait cycles as the average 65 or 70 year old. Long-term studies demonstrate that polyethylene wear is a major cause of long-term failure. Newer bearing materials such as cross-linked polyethylenes show promise in reducing wear in THA and more recently in TKA. Femoral component material can significantly influence wear. Studies reveal that in vivo femoral component scratching significantly increases polyethylene wear. Oxidised Zirconium (OxZr) has been shown to significantly reduce polyethylene wear in knee simulators. The ceramic surface has greater lubricity and is harder. We have examined the in vivo performance on Oxidised Zirconium in several studies. These studies reveal that the harder Oxidised Zirconium femoral surface is much more resistant to scratching than CrCo femurs. Retrieval analysis revealed a 12 fold increase in scratching of CrCo femoral components compared to OxZr. Profilometry analysis of matched pairs of femoral components demonstrates that the surfaces of the CrCo implants significantly roughen over time while the OxZr do not significantly change in vivo. These comparative studies also showed less damage to the tibial polyethylene bearings with the OxZr femoral components compared to CrCo. Extending longevity of TKA requires improved materials to reduced wear. To optimise this, bearing surfaces must be coupled with improvements in both tibial polyethylene and femoral component materials

Cemented total hip arthroplasty has become an extremely successful operation with excellent long term results. Although showing decreasing popularity in North America, it always remained a popular choice for the elderly patients in Europe and other parts of the world. Besides optimal component orientation, a proper cementing technique is of major importance to assure longevity of implant fixation. Consequently a meticulous bone bed preparation assures the mechanical interlock between the implant component, cement and the final bone bed. Cementing the acetabular side should include preservation of the transverse acetabular ligament and clear identification of the medial wall. Medialisation and deepening of the socket are important at reaming, to ensure a containment of the cup. The contact of the cup to cancellous bone should be maximised. Either smaller reamers or 4–6mm anchoring holes can be drilled to the superior sclerosis. Smaller defects can be curettage, while larger ones might require cancellous bone grafting. Of major importance is the thoroughly pulsatile jet lavage with saline to irrigate the cancellous bone bed, to reduce fat and blood lamination. After final irrigation, before cementation, dry sponges are slightly impacted into the cavity, to dry it out. Cementation usually requires 40g of high viscosity bone cement. Immediate pressurisation of the cement into the bone bed should start after a general application time in our institution between 2.5 to 3 minutes after mixing; with either a sterile glove filled with a sponge or designated company specific pressuriser. Sustained pressurisation should be done for 1 minute. The original cup should be 3–4mm smaller than the last reamer, to ensure circumferential cement mantle. Insertion principle includes medialisation first, followed by gradual angulation of the cup. In appropriate position, a balled pressuriser maintains pressure without further moving of the implant, until cement hardening. Remnant cement can be removed with osteotomes, while remaining osteophytes should be flush with implant. Femoral Side: First the fossa pyriformis should be clearly identified, including the posterolateral entry point of the prosthesis. The femoral neck cut is usually 1.5–2cm above the minor trochanter, based on the preoperative planning and implant type. Opening of the canal is done with an awl or osteotome, followed by any blunt tipped instrument, to follow the intramedullary direction. A box osteotome opens the lateral portion of the femoral neck, gently to preserve as much cancellous bone as possible. Sequential broaching follows carefully and according to the planning, to ensure preservation of 2–3mm cancellous bone for interdigitation. Some systems might require over-broaching by one size. Trialing is done with the broach. Following, irrigation using a long nozzle pulsatile lavage, reduces the chance for fat embolism. A cement restrictor is then placed 1.5–2cm distal to the tip of the stem, to ensure an adequate cement mantle distally. A second complete pulsatile irrigation of the canal follows, to minimise bleeding, followed by a dry sponge. Cement mixing is vacuum based in the meantime, usually 60–80g. We prefer the use of low dose antibiotic laden cement in our set up. Two to three minutes after mixing, the cement is applied rapidly in a retrograde technique with a cement gun, placing the nozzle tip against the cement restrictor. The gun is “pushed” out during the application, rather than being withdrawn from the canal. Proximal pressurisation is first done by thumb, then with a proximal seal for 1 minute. The stem is inserted slowly using steady manual pressure, in the center of the cement mantle, however, should never be impacted. The stem is aligned with the previously defined lateral entry point and is held in position until the cement hardens. The desired outcome is a cement interdigitation into cancellous bone for 2–3mm and an additional mantle of 2mm pure cement

Ceramic heads and highly cross-linked polyethylene (HXLPE) as bearing surface materials have been introduced to reduce the production of polyethylene wear particles. The present study hypothesized that the wear rate of HXLPE could be further reduced when combined with a ceramic head. The purpose of this study was to compare the in vivo wear of Longevity HXLPE against cobalt-chromium and zirconia heads after a minimum 5-year follow-up. A prospective cohort study was performed in 102 cementless total hip arthroplasties (THAs) with the Longevity HXLPE socket (Zimmer) between June 2000 and October 2001. Same prostheses were used in all cases both acetabular cups (Trilogy; Zimmer) and femoral stems (Versys Fiber Metal Taper; Zimmer). 26-mm zirconia heads (NGK) or 26-mm cobalt-chromium heads (Zimmer) were randomly used in 51 hips each. A minimum 5-year follow-up was completed for 47 hips with zirconia heads and 46 hips with cobalt-chromium heads. Two-dimensional linear wear of Longevity HXLPE was measured using computer-assisted methods (PolyWare) on annual x-rays, and total head penetration rates and steady state wear rates were calculated. In addition, periprosthetic osteolysis was evaluated. At a mean 6-year follow-up, the total head penetration rates were 0.034±0.016 mm/year (zirconia) and 0.031±0.015 mm/year (cobalt-chromium). The steady state wear rates were −0.01 mm/year (zirconia) and −0.01 mm/year (cobalt-chromium). No significant difference was seen between the two groups (p=0.4 and p=0.91). Osteolysis was not observed around prostheses in any hips. In conclusion, no advantage was seen for the zirconia head compared with the cobalt-chromium head in this time period

Evaluating 30 years of total hip arthroplasty, we analyse the factors that determine longevity in terms of implant, design, materials, instrumentation and operative technique. Simple implant design is important. Cups should be thick-walled and cemented. Particularly when cross-linked polyethylene is used, the size of the head bears little relation to the prevention of wear, but using too small a head seriously impairs stability. Improved cement and cementing techniques now facilitate exact placement. Traction instrumentation controls leg length equalisation and periarticular tissue tension, and further enhances stability

Using a larger diameter femoral head in total hip arthroplasty (THA) has advantages in terms of the increased joint stability and range of motion. And the wear resistance of highly cross-linked polyethylene (HXLPE) even combined with a larger head has already been demonstrated by in vitro studies. The purpose of this study was to compare the in vivo wear of Longevity HXLPE sockets against 32 mm and 26 mm heads at a 5-year follow-up. From November 2000 to November 2001, 51 primary cementless THAs were performed with a 26 mm cobalt-chromium head and a Longevity HXLPE socket (Zimmer). A cohort of 32 mm cobalt-chromium heads was comprised of 51 THAs with the same prosthesis performed from December 2001 to December 2003. No significant differences between the groups were observed in gender, age, and BMI, however, polyethylene liners with 32 mm heads were significantly thinner than those with 26 mm heads. Two-dimensional linear wear was measured using PolyWare software on annual x-rays, and total head penetration rates at postoperative 5-year and steady state wear rates were calculated. In addition, periprosthetic osteolysis was evaluated. At the 5-year follow-up, the total head penetration rates were 0.047±0.022 mm/year with 26 mm heads and 0.048±0.026 mm/year with 32 mm heads. The steady state wear rates were −0.008 mm/year with 26 mm heads and 0.001 mm/year with 32 mm heads. No significant differences were seen between the two groups (p=0.82 and p=0.24). Osteolysis was not observed around pros-theses in any hips. At the 5-year follow-up, the wear rate of Longevity HXLPE was very low. A Longevity HXLPE socket will undergo the same level of wear whether with a 32 mm head or a 26 mm head

Introduction. The effectiveness of patient specific instrumentation (PSI) to perform total knee arthroplasty (TKA) remains controversial. Multiple studies have been published that reveal conflicting results on the effectiveness of PSI, but no study has analyzed the contact kinematics within knee joints replaced with the use of PSI. Since a departure from normal kinematics can lead to eccentric loading, premature wear, and component loosening, studying the kinematics in patients who have undergone TKA with PSI can provide valuable insight on the ability of PSI to improve functionality and increase longevity. The goal of the present study was to compare femoral and tibial component migration (predictive of long-term loosening and revision) and contact kinematics following TKA using conventional instruments (CI) and PSI based surgical techniques. Methods. The study was designed as a prospective, randomized controlled trial of 50 patients, with 25 patients each in the PSI and CI groups, powered for radiostereometric analysis (RSA). Patients in the PSI group received an MRI and standing 3-foot x-rays to construct patient-specific cut-through surgical guides for the femur and tibia with a mechanical limb alignment. All patients received the same posterior-stabilized implant with marker beads inserted in the bone around the implants to enable RSA imaging. Patients underwent supine RSA exams at multiple time points (two and six weeks, three and six months, and one and two years). At 2 years post-op, a series of RSA radiographs were acquired at different knee flexion angles, ranging in 20° increments from 0° to 120°, to measure the tibiofemoral contact kinematics. Migrations of the femoral and tibial components were calculated using model-based RSA software. Kinematics were measured for each condyle for magnitude of excursion, contact location, and stability. Results. There were no differences (p > 0.05) between the PSI and CI groups for demographics or pre- and post-operative patient reported outcome scores. Three patients in the PSI group and seven patients in the CI group (p = 0.28) had a post-operative limb alignment outside of the neutral target (>3° varus or valgus). There was no difference in the change of tibial slope from pre- to post-operation between groups (p = 0.49). There were no differences (p > 0.05) in translations or rotations in any individual plane across all time points for either the tibial or femoral components. Maximum total point motion (MTPM) at 6 months for the tibial component was 0.54 ± 0.25 mm in the CI group and 0.51 ± 0.22 mm in the PSI group (p = 0.77), placing both groups at the low end of the “at risk” category for predicted loosening. Change in MTPM from 6 months to 1 year and again from 1 year to 2 years was <0.2 mm, indicating both groups of implants had stable fixation. Femoral component MTPM was also not different (p > 0.05) between groups. There was no significant difference between PSI and CI groups with respect to magnitude of excursion on both medial (p = 0.54) and lateral (p = 0.81) condyles. There was also no difference in contact locations on both the medial and lateral condyles (p = 0.28 to 0.91) for all angles of flexion. There was no significant difference present between PSI and CI groups when comparing the stability for both the medial (p = 0.06) and lateral (= 0.85) condyles. Condylar separation was present in 3/20 CI patients and 0/16 PSI patients (p = 0.24). Conclusion. Using the latest RSA criteria for predicting failure from early migration, the use of PSI does not provide an advantage over CI for preventing aseptic loosening. Moreover, PSI did not provide any substantial advantage over CI for TKA surgery with respect to contact kinematics

Background. Loss of muscle mass (sarcopenia) and function in ageing are associated with reduced functional ability, quality of life and reduced life expectancy. In cancer patients, age related muscle loss may be exacerbated by cachexia and poor nutritional intake. Individuals with widespread disseminated disease are most prone to increasing functional decline, increased morbidity and accelerated death. However subjective assessments of physical performance have been shown to be poor indicators of life expectancy in these patients. Aims. To develop an objective measure to aid calculation of life expectancy in cancer by investigating the association between objectively measured lean muscle mass and longevity, in 41 patients with known spinal metastases from all cause primaries. Methods. Lean muscle mass was calculated as total psoas area (TPA)/height (m)2. Two blinded doctors independently calculated TPA from CT images at the L3 level, performed routinely within 7 days of diagnosis of spinal metastases. Time to death was recorded from retrospective analysis of hospital notes. Results. Of patients within the highest tertile for muscle mass 85% were alive at one year, compared with 50% in the lowest tertile. Conclusion. Death within one year in individuals with spinal metastases is significantly higher in patients with low lean muscle mass at presentation

Aims

We aimed to evaluate the long-term outcome of highly cross-linked polyethylene (HXLPE) cemented acetabular components and assess whether any radiolucent lines (RLLs) which arose were progressive.

Although conventional thinking and teaching have implicated weight and body mass index (BMI) in premature failure of total knee arthroplasty (TKA) there is scant evidence based confirmation of this belief. Furthermore, there is little knowledge regarding the precise effect of BMI on functional outcomes following TKA. We performed this study to assess the effect of weight on the longevity of TKA and on outcomes following TKA revision (TKAR). 186 consecutive subjects undergoing TKAR in a 17-center prospective cohort study, had data collected on weight (pounds), BMI and time elapsed between primary and revision surgery (T). The Physical Component Score (PCS) of the Short Form-36 (SF-36), the Western Ontario and McMaster Universities Osteoarthritis (WOMAC) Index, and the Knee Society Score (KSS) were also collected preoperatively and at 6-month follow-up. Univariate, bivariate and multivariate statistical methods were used in the analysis. The mean BMI and weight were 31.8 (54% of subjects had a BMI > 30) and 200 pounds (range 107–350) respectively. The distribution of both measures of excessive weight was close to normal. Average time between primary and revision procedures (T) was 7.3 years (range 6 months to 27 years). Using linear regression, T significantly decreased as weight (BMI) increased. Mean SF-36 PCS, WOMAC and KSS-Function scores were significantly improved 6 months after revision surgery. However, BMI and, in particular, weight were predictive of worse physical functional outcomes. This study demonstrates the deleterious effect of weight on both the longevity of primary TKA as assessed at the time of revision and on functional outcomes following TKAR. Although further prospective data regarding this population is indicated, the current findings direct us towards better outcomes prediction for overweight patients and more effective counselling and appropriate management of these patients

Summary Statement. The chemistry, amount, morphology, and size distribution of wear debris from silicon nitride coatings generated in the bearing surface can potentially reduce the negative biological response and increase the longevity compared to conventional materials in joint replacements. Introduction. Total hip implants have a high success rate at 15 years of implantation, but few survive over 25 years. At present, revisions are mostly due to aseptic loosening, believed to mainly be caused by the biological response to wear debris generated in the joint bearing. For the polymer liners the size of the wear debris determines the biological response, while for metal bearing surfaces a limitation is the metal ion release. When ceramics are used, the wear debris is in general small and mechanical factors may be the main cause for failure. A more recent, experimental alternative is to let the well-known metallic substrate serve as the soft, tough bulk, and additionally apply a hard and smooth ceramic coating. In this way a lower wear rate and reduced metal ion release could be obtained. Furthermore, the chosen composition, silicon nitride (SixNy), contains no detrimental ions, and silicon nitride debris has been shown to slowly dissolve in aqueous medium. Altogether, it can potentially increase the longevity of the implant. However, the debris from SixNy coatings has not yet been characterised. In this study, a wear model test was performed to generate wear debris from SixNy coatings. The debris was characterised using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) in combination with computational calculations. Methods. Silicon nitride coatings deposited on flat cobalt chromium alloy (ASTM F75) were worn in a reciprocating ball on disc setup in a 25% serum solution at 37°C against an alumina ball with a load of 1.5 N. Wear debris was separated using serum digestion with hydrochloric acid (ISO 17853:2011) and examined in SEM in combination with EDS. As reference polyethylene (PE) was used to verify that relevant particles sizes were achieved. The SEM images were processed using a modified MATLAB-script originating from Cervera Gontard et al. [1], identifying the particles and calculating their size. Results. Particles generated from SixNy coatings (n=62) a size distribution D50 [D10-D90] of 0.29 µm [0.16–0.69] and were round to oval in shape. The PE particles (n=70) had a size distribution of 0.29 µm [0.13–1.3], shaped similar to the SixNy particles or with a more elongated shape. Discussion and conclusions. PE wear debris has been reported to lie in the size range of nm up to several μm in vivo, with a large proportion within the critical size for macrophage activation (0.2 to 0.8 μm). The model test reports relevant sizes and shape of PE debris, confirming the validity of the method. Particles generated from the SixNy coatings showed a smaller size range than PE, however most particles were within the critical size range for biological activation. In conclusion, this model test could be used to generate what we believe are relevant sizes and shapes of PE and SixNy wear debris and to learn more at an early stage of prediction of wear debris. Further dissolution studies as well as studies on the in vitro and in vivo cell response to these types of particles will be performed. The authors thank the Swedish Foundation for Strategic Research (SSF) through MS2E and FP7 NMP project LifeLongJoints for financial support, as well as Linköping University for the coating facilities and expertise

Introduction. A thorough understanding of wear patterns and failure mechanisms of TKA components in the context of pre-revision knee kinematics is advantageous for component designers, manufacturers and surgeons alike. Traditional gait analysis provides an experimental technique to determine in vivo kinematics but is often limited by its cumbersome nature, infrastructure intensiveness and time. The recent introduction of the KneeKG (Emovi Inc, Canada) as a stand-alone knee motion tracking system which uses infrared technology provides a great opportunity to quickly, easily and routinely monitor patients at the clinical level, especially those being revised for component failure. This pilot study was conducted to examine pre-revision knee kinematics and subsequent wear patterns and failure mechanisms observed on the UHMWPE inserts upon retrieval in a cohort of TKA revision patients. We hypothesize that motion patterns can provide surgeons a unique insight into the status of the UHMWPE insert and implant longevity. Methods. Patients requiring revision due to failure of the UHMWPE insert were recruited in this study after institutional ethical approval and written informed consent of the patients was obtained. Motion of the affected knee was quantified using a stand-alone infrared tracking system (KneeKG, Emovi Inc, Canada) whilst the patient was walking on a treadmill. All analyses were conducted within our institutional Physiotherapy Department. The KneeKG system is composed of passive motion sensors fixed on a validated knee harness, an infrared motion capture system (Polaris Spectra, Northern Digital Inc, USA) and a computer equipped with the Knee3D software suite (Emovi). Following application of the KneeKG trackers a calibration procedure was performed to identify joint centres and define a coordinate system on each body segment. After a treadmill habituation period of between 6 and 10 min, a trial was then conducted at the patient's comfortable treadmill gait speed over 45 sec. Averaged clinical rotations and translations of the tibia as a function of gait cycle were output by the system, and a report highlighting and detailing biomechanical deficiencies as compared to a database of normal controls automatically generated. Following the scheduled revision surgery the retrieved components were formalin-fixed and brought to our laboratory for a routine retrieval workup. All revisions were performed by a single surgeon. Components were analysed using optical and scanning electron microscopy techniques for regions of polishing, burnishing, pitting, delamination, deformation, scratching and embedded debris. Wear maps and scores were generated and correlated with pre-revision kinematics for each patient. Results. The KneeKG was successfully applied to patients in this pre-revision scenario, requiring less than 30 minutes to complete per case. Variations in knee kinematics have been observed, and the analysis of retrieved components is ongoing. Discussion. This study has demonstrated that knowledge of pre-revision knee kinematic patterns can provide a unique insight into wear and failure mechanisms of the UHMWPE liner. Whilst this study is currently limited by a relatively small sample size, recruitment is continuing with a view to the possible generation of odds ratios for UHMWPE insert failure mechanisms based on kinematic signatures

Aims

The purpose of this study is to examine six types of bearing surfaces implanted at a single institution over three decades to determine whether the reasons for revision vary among the groups and how long it takes to identify differences in survival.

Background. Resveratrol is a polyphenolic compound commonly found in the skins of red grapes. Sirtuin 1 (SIRT1) is a human gene that is activated by resveratrol and has been shown to promote longevity and boost mitochondrial metabolism. We examined the effect of resveratrol on normal and osteoarthritic (OA) human chondrocytes. Methods. Normal and OA chondrocytes were incubated with various concentrations of resveratrol (1 µM, 10 µM, 25 µM and 50 µM) and cultured for 24, 48 or 72 hours or for six weeks. Cell proliferation, gene expression, and senescence were evaluated. Results. SIRT1 was significantly upregulated in normal chondrocytes with resveratrol concentrations of 25 µM and 50 µM on both two- (2D) (both p = 0.001) and three-dimensional (3D) cultures (p = 0.008 and 0.001, respectively). It was significantly upregulated in OA chondrocytes treated with 10 µM, 25 µM and 50 µM resveratrol on 2D cultures (p = 0.036, 0.002 and 0.001, respectively) and at 50 µM concentration on 3D cultures (p = 0.001). At 72 hours, the expression of collagen (COL)-10, aggrecan (AGG), and runt-related transcription factor 2 (RUNX2) was significantly greater in both 25 µM (p = 0.011, 0.006 and 0.015, respectively) and 50 µM (p = 0.019, 0.004 and 0.002, respectively) resveratrol-treated normal chondrocyte cultures. In OA chondrocytes, expression of COL10 and RUNX2 was significantly greater in 25 µM (p = 0.004 and 0.024) and 50 µM (p = 0.004 and 0.019) cultures at 72 hours on 3D cultures. Conclusions. At concentrations of 25 µM and/or 50 µM, resveratrol treatment significantly upregulates SIRT1 gene expression in normal and osteoarthritic chondrocytes. Resveratrol induces chondrocytes into a hypertrophic state through upregulation of COL1, COL10, and RUNX2. Cite this article: Bone Joint Res 2014;3:51–9