In 2020 almost 90% of femoral heads for total hip implants in Germany were made of ceramic. Nevertheless, the cellular interactions and abrasion mechanisms in vivo have not been fully understood until now. Metal transfer from the head-neck taper connection, occurring as smear or large-area deposit, negatively influences the surface quality of the articulating bearing. In order to prevent metal transfer, damage patterns of 40 Biolox delta ceramic retrievals with CoC and CoPE bearings were analysed. A classification of damage type and severity for each component (n=40) was done according to an established scoring system. To investigate the physical properties, the surface quality was measured using confocal microscopy, quantitative analysis of phase composition were performed by Raman spectroscopy and qualitative analysis of metal traces was done by scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDX). The periprosthetic tissue was analysed for abrasion particles with SEM and EDX. Both bearing types show different damage patterns. Dotted/ drizzled metal smears were identified in 82 % of CoC (n=16) and 96 % of CoPE (n=24) bearings. Most traces on the ceramic heads were identified in the proximal area while they were observed predominantly in the distal area for the ceramic inlays. The identified marks are similar to those of metallic bearings. Metallic smears lead to an increase of up to 30 % in the monoclinic crystalline phase of the ceramic. The roughness increases by up to six times to Ra=48 nm. Ceramic and metallic wear particles from the articulating surfaces or head neck taper junctions were found in the periprosthetic tissue. Damage patterns on CoC hip implants seem to be similar to those of metallic implants. More detailed analysis of CoC implants are needed to understand the described damage patterns and provide advice for prevention

Background. We searched -in transverse ultrasound view- the value of the difference (Delta) between -proximal to the tunnel- CSA (a) and -in the tunnel's inlet- CSA (b) for separating normal from abnormal median nerves. Methods. 51 patients –suspicious for CTS- underwent Phalen and Tinnel tests. After that, we used a high frequency ultrasound to measure CSAa, CSAb and Delta CSA in both hands. 33 of our 51 patients did not experience any clinical symptoms at the contralateral hand, so that we could perform a comparative study of normal and pathological median nerves (on the same patients). Then, all of them completed a Q-DASH questionnaire and a visual analogue scale (VAS 100/100) and they carried through with a nerve conduction study (NCS). Results. We found that a CSAb more than 0,010 and a Delta CSA > 0,003 are both very sensitive findings for CTS, but only DeltaCSA has good specificity. Comparing to NCS the Delta CSA>0,003 had no statistical difference in sensitivity, specificity, true negative and true positive results. Furthermore, patients with Delta CSA>0,009 were suffering from heavy CTS according to NCS, Q-DASH and VAS. On the other way, a Delta CSA between 0,003 and 0,006 suggests a mild or moderate CTS. Conclusion. Delta CSA could be the golden standard for the detection of CTS in patients that feel uncomfortable to undergo NCS. We propose a grading scale that distinguish mild or moderate syndromes (where we could try a conservative treatment) from heavy syndromes and help as on decision-making

We have developed a decellularised porcine superflexor tendon (pSFT), which has shown promising regenerative capacity in an ovine model of anterior cruciate ligament (ACL) repair. This study investigated the strain rate dependent and dynamic mechanical properties of native and decellularised pSFTs. Decellularisation was carried out using a previously established procedure, including antibiotic washes, low concentration detergent (0.1% sodium dodecyl sulphate) washes and nuclease treatments. Three different strain rates were employed: 1, 10 & 100%s-1 (n=6 for all groups). Toe-region modulus (E0), linear-region modulus (E1), transition coordinates (εT, σT), tensile strength (UTS) and failure strain were calculated. For DMA, specimens were loaded between 1 & 5MPa with increasing frequency up to 2Hz. Dynamic (E*), storage (E') and loss (E'') moduli, and tan delta were calculated for native and decellularised groups (n=6). Data was analysed by 2-way ANOVA and Tukey post-hoc test (p<0.05). For decellularised tendons, altering the strain rate did not affect any of the static tensile properties. For native pSFTs, the UTS, failure strain and E1 were not affected by changing the strain rate. Increasing the strain rate significantly increased E0 (1% vs 10% and 1% vs 100%) and σT (1% vs 100%) and decreased εT (1% vs 10% and 1% vs 100%) for native pSFT. E*, E' and E'' were all significantly reduced in decellularised specimens compared to native controls across all frequencies investigated. No significant differences were found for tan delta. Evidence of strain rate dependency was witnessed in the native pSFTs by increase of the toe region modulus and displacements of the transition point coordinates. This response was not seen in the tissue following decellularisation. DMA demonstrated a reduction in dynamic, storage and loss moduli. Tan delta (E''/E') remained unchanged, indicating reductions in solid and fluid components are interlinked

Background. The CoCrMo large bearings had shown a high failure rate, because of metal ion and particle release. Alumina matrix composite (AMC) ball heads have shown to mitigate such phenomena. The aim of this study was to investigate the leaching properties of AMC clinically as well as experimentally. Methods. Two patient groups were compared: a control group (n=15) without any implant (Controls) and 15 Patients with unilateral treatment with Biolox delta ceramic-on-ceramic (CoC). Whole-blood samples of Controls and Patients (after 3 and 12 months from treatment with CoC) were measured by means of trace element analysis using a HR-ICPMS. The leaching behaviour of BIOLOX delta was also analysed in-vitro: five Biolox delta heads and five CoCrMo heads were immersed in serum for seven days at 37°C. Aluminium, cobalt, chromium and strontium were detected based on HR-ICPMS. Results. In Patients, most elements remained below the limit of detection (LoD), except for aluminium and strontium. The aluminium values of Controls were below the LoD (27.2μg/L). The values of Patients after three months show a median of 34.2μg/L and after 12 months 37.1μg/L (p=0,510). Strontium ranged from 39.7μg/L of Controls and 79.6μg/L and 70.7μg/L of Patients, after three and twelve months, respectively. This difference was not statistically significant (p=0,322). The leaching experiments showed high amounts of cobalt (177.3μg/L) and chromium (4.2μg/L) released by CoCrMo. Ceramic heads didn't show any significant release. Conclusions. The current study revealed that there was no significant increase of any element in patients with CoC bearings. Metal heads released high values of cobalt in leaching test. As this release occurred even without any joint articulation, as shown in the experiments, surface corrosion seems to be a relevant mechanism in the ion release of metal bearings. A limitation of the study is that Controls differed from Patients within the clinical trial. Level of evidence. III

Posterior spinal surgery is associated with a significant amount of blood loss. The factors predisposing the patient to excessive bleeding-and therefore transfusion- are not well established nor is the effect of transfusion on the outcomes following spinal surgery. We had two goals in this study. First, we were to investigate any suspected risk factors of transfusion in posterior thoraco-lumbar fusion patients. Second, we wanted to observe the negative impact-if one existed- of transfusion on the outcomes of surgery. All adults undergoing posterior thoraco-lumbar spine fusion in our institution from May 2015 to May 2018 were included. Data collected included demographic data as well as BMI, preoperative hemoglobin, American Society of Anesthesiologists classification (ASA), delta Hemoglobin, estimated blood loss, incidence of transfusion, number of units transfused, number of levels fused, length of stay and re-admission within 30 days. The data was analyzed to correlate these variables with the frequency of transfusion and then to assess the association of adverse outcomes with transfusion. 125 patients were included in the study. Only 6 patients (4.8%) required re-admission within the first 30 days after discharge. Length of stay averaged 8.4 days (3–74). 18 patients (14.4%) required transfusion peri-operatively. When multiple variables were analyzed for any correlation, the number of levels fused, age and BMI had statistically significant correlation with the need for transfusion (P <0.005). Patients undergoing posterior thoraco-lumbar fusion are more likely to require blood transfusion if they were older, over-weight & obese or had a multi-level fusion. Receiving blood transfusion is associated with increased complication rates

Wear particles produced by alumina ceramic-on-ceramic (CoC) bearings cause a minimal immunological response with low cytotoxicity and inflammatory potential. 1, 2. However, more comprehensive immunological studies are yet to be completed for the composite CoC (zirconia-toughened, platelet reinforced alumina) hip replacements due to difficulties in isolating the very low volume of clinically relevant wear debris generated by such materials in vitro. The aim of this study was to compare the cytotoxic effects of clinically relevant cobalt chromium (CoCr) nano-particles with commercial composite ceramic particles. Composite ceramic particles (commercial BIOLOX® delta powder) were obtained from CeramTec, Germany and clinically relevant CoCr wear particles were generated using a six station pin-on-plate wear simulator. L929 fibroblast cells were cultured with 50µm. 3. of CoCr wear debris or composite ceramic particles at low to high volumes ranging from 500µm. 3. –0.5µm. 3. per cell and the cyctotoxic effects of the particles were assessed over a period of 6 days using the ATP-Lite™ cell viability assay. The composite ceramic particles were bimodal in size (0.1–2µm & 30–100nm) and showed mild cytotoxic effects when compared with equivalent particle volumes (50µm. 3. ) of clinically relevant CoCr nano-particles (10–120nm). The CoCr nano-particles had significant cytotoxic effects from day 1, whereas the composite ceramic particles only showed cytotoxic effects at particle concentrations of 50 and 500µm. 3. after 6 days. The increased cytotoxicity of the clinically relevant CoCr nano-particles may have been attributed to the release of Co and Cr ions. This study demonstrated the potential cytotoxic effects of model ceramic particles at very high volume concentrations, but it is unlikely that such high particle volumes will be experienced routinely in vivo in such low wearing bearing materials. Future work will investigate the longer-term effects on genotoxicity and oxidative stress of low volumes of clinically-relevant generated BIOLOX® delta ceramic wear particles

A complete design-manufacturing process for delivering customized foot orthoses by means of digital technologies is presented. Moreover, this feasibility study aims to combine a semi-automatic modelling approach with the use of low-cost devices for 3D scanning and 3D printing. In clinical practice, traditional methods for manufacturing customized foot orthoses are completely manual, mainly based on plaster casting plus hand fabrication, and are widely used among practitioners. Therefore, results depend on skills and expertise of individual orthoptists and podiatrists that need considerable training and practice in order to obtain optimal functional devices. On the other side, novel approaches for design and manufacturing customized foot orthoses by means of digital technologies (generally based on 3D scanning, 3D modelling and 3D printing) are recently reported as a valid alternative method to overcome these limitations. This study has been carried out in an interdisciplinary approach between the staff of Design and Methods in Industrial Engineering and the staff of Podology with the aim to assess the feasibility of a novel user-friendly and cost-effective solution for delivering customized functional foot orthoses. More specifically, a Generative Design (GD) workflow has been developed to enable practitioners without enough CAD skills to easily 3D modelling and interactively customize foot orthoses. Additionally, low-cost devices for 3D scanning and 3D printing that have been acquired by the Podology Lab, were also tested and compared with the high-cost ones of the Department of Industrial Engineering. The complete process is divided into three main steps. The first one regards the digitization of the patient's foot by means of 3D laser scanner devices. Then a user-friendly 3D modelling approach, developed for this purpose as GD workflow, allows interactively generating the customized foot orthosis, also adjusting several features and exporting the watertight mesh in STL format. Finally, the last step involves Additive Manufacturing systems to obtain the expected physical item ready to use. First, for what concerns the digitizing step, the acquired data resulting from 3D scanning by means of the low-cost system (Sense 3D scanner) appears accurate enough for the present practical purposes. Then, with respect to the 3D modelling step, the proposed GD workflow in Grasshopper is intuitive and allows easily and interactively customizing the final foot orthosis. Finally, regarding the Additive Manufacturing step, the low cost 3D printer (Wasp Delta 40 70) is capable to provide adequate results for the shell of the foot orthosis. Moreover, this system appears really versatile in reason of the capability to print in a wide range of different filaments. Therefore, since the market of 3D printing filaments is rapidly growing, building sessions with different materials (both flexible and rigid such, for example, PLA, AB and PETG) were completed. This study validated, in terms of feasibility, that the use of a GD modelling approach, in combination with low-cost devices for 3D scanning and 3D printing, is a real alternative to conventional processes for providing customized foot orthosis. Moreover, the interdisciplinary approach allowed the transfer of skills and knowledge to the practitioners involved and, also, the low-cost devices Sense 3D scanner and Wasp Delta 40 70 that have been acquired by the Podology Lab, were demonstrated suitable for this kind of applications

Summary Statement. A new 28mm-diameter ceramic-on-ceramic (COC) acetabular bearing couple (Biomet Orthopedics) showed extremely low wear, even under adverse microseparation conditions∗. The wear results are similar or more favorable than those reported for clinical retrievals and wear testing of similar ceramic bearings. Introduction. A new acetabular shell and ceramic insert design (Biomet) incorporates features to help prevent malalignment during implantation, while still providing secure fixation within the acetabular shell. The incorporation of Biolox. ®. Delta (zirconia toughened alumina, CeramTec) material should provide improved wear resistance over pure alumina ceramics. The goal of this study is to evaluate the wear durability of this system for standard and microseparation testing. Materials & Methods. The 28 mm diameter ceramic heads and inserts (CeramTec) were seated on taper spigots and within acetabular shells (Biomet), respectively. Six sets of parts were tested for 5M cycles of standard hip wear testing (ISO 14242) and an additional six sets of parts for 2M cycles of microseparation testing. The microseparation testing protocol included a steep cup angle (60° in-vivo), side load, and reduced axial load to induce head-liner separation. The lateral displacement was increased from 0.5mm, to 1mm, and then to 2mm in order to replicate wear features observed in extreme situations of clinical retrievals. [1]. The parts were weighed (gravimetric wear rates) and photographed throughout the test. SEM, transformation, and wear debris analyses were completed. Results. The steady-state wear rate throughout standard testing was 0.0094 +/− 0.0029 mm. 3. /10. 6. cycles (+/-95% CI). The initial 0.5mm microseparation distance (0–1M cycles) showed no signs of wear. Most heads showed wear stripes after increasing to 1.0mm (1–1.5M cycles), and then all test parts showed stripes after increasing to 2mm. The increased visibility in wear stripes correlated with an increased level of measured wear. For the 2mm separation-distance testing interval, the wear rate was 0.178 +/− 0.052mm. 3. /10. 6. cycles. Discussion/Conclusion. The lack of wear stripes during 0.5mm of microseparation is an indication of the strength of the implants. A distance of 1–2mm is an extreme level of microseparation and the 60° in-vivo cup inclination created an even worse-case situation for wear; however, the implants showed excellent mechanical strength and low wear rates. SEM and transformation analyses showed minimal wear and evidence of stress-induced ceramic toughening. Microseparation testing at another lab . [2]. has shown a similarly low wear rate (0.5 mm. 3. /10. 6. cycles) for Biolox. ®. Delta ceramic, with Biolox. ®. Forte (alumina ceramic, without zirconia) showing a considerably higher wear rate (6.3mm. 3. /10. 6. cycles). The standard testing wear rate (0.0094+/-0.0029 mm. 3. /10. 6. cycles) was much lower than the average wear rate (0.69+/-0.63 mm. 3. /10. 6. cycles) of several COC implant retrievals by Walter . [1]. The 28mm steady-state wear rate of this test is better than or equal to the wear rate (0.0101 mm. 3. /10. 6. cycles) observed in other 28mm COC systems.∗∗. ∗Ceramic-on-Ceramic articulation is not cleared for use in the United States. ∗∗Laboratory results are not necessarily indicative of clinical performance

Background. Many factors contribute to the occurrence of edge-loading conditions in hip replacement; soft tissue tension, surgical position, patient biomechanical variations and type of activities, hip design, etc. The aim of this study was to determine the effect of different levels of rotational and translational surgical positioning of hip replacement bearings on the occurrence and severity of edge-loading and the resultant wear rates. Method. The Leeds II Hip-Joint Simulator and 36mm diameter alumina matrix composite ceramic bearings (BIOLOX delta, DePuy Synthes, UK) were used in this study. Different levels of mismatch between the reconstructed rotational centres of the head and the cup were considered (2, 3 and 4mm) in the medial-lateral axis. Two cup inclination angles were investigated; an equivalent to 45 and 65 degrees in-vivo, thus six conditions (n=6 for each condition) were studied in total with three million cycles completed for each condition. The wear of the ceramic-on-ceramic bearings were determined using a microbalance (Mettler Toledo, XP205, UK) and the dynamic microseparation displacement was measured using a Liner Variable Differential Transformer. Results. When a translational joint centre mismatch was coupled with a higher cup inclination angle, the severity of edge-loading increased when compared with the effect of those variables applied individually. Increasing the medial-lateral joint centre mismatch from 2 to 3 to 4mm resulted in increased wear rates under both cup inclination angles, with the 65 degree cup inclination angle having significantly higher wear rate than the cup inclination angle of 45 degree (p=0.02, p=0.02, and p<0.01 respectively). Conclusion. The cups with a 45 degree inclination angle showed greater resistance to dynamic microseparation as a result of joint centre mismatch. This study demonstrated that optimal position should not only consider the rotational position of the acetabular cup but also the relative centres of rotation of the head and the cup. Disclosure. John Fisher is a paid consultant to DePuy Synthes. Jonathan Thompson and Graham H. Issac are employees at DePuy Synthes

Summary Statement. The frictional torque of ceramic-on-ceramic bearings tended to increase with increasing the bearings size (32, 48, 56mm). However, the frictional torque was significantly lower than that measured on metal-on-metal bearings under well positioned and well lubricated conditions. Introduction. Larger head size in total hip replacement theoretically provides increased range of motion and enhanced stability. However, there are potential clinical concerns regarding increased frictional torques with large diameter metal-on-metal bearings causing loosening of the acetabular cups and corrosion at the taper. The aim of this study was to determine the frictional torques of large diameter BIOLOX® delta ceramic-on-ceramic bearings. Materials and Methods. The single-station pendulum friction simulator (SimSol, UK) was used to determine the frictional torque of three ceramic-on-ceramic bearing sizes: 32mm and 48mm (DeltaMotion®, DePuy Synthes Joint Reconstruction, Leeds, UK) and a 56mm prototype design. Four repeats were tested for each bearing size using 100% new-born calf serum, 25% new-born calf serum and water as lubricants. The input profiles were a simplified loading regime with a peak of 2kN and an angular motion of ±25° [1]. The frictional torque was determined under swing phase loads of 25N, 100N or 300N. The bearings were tested under standard conditions where the cup was positioned so the face was horizontal to the loading axis and at an inclination angle equivalent to 65° in vivo. Results. When lubricated with 100% serum, size 48mm bearings showed similar frictional toque to the 32mm bearings (1.5Nm and 1.7Nm respectively, p=0.28), however, the frictional torque of the 56mm prototype design bearings was significantly higher (2.2Nm, p=0.01). When using 25% serum, there was a trend of increased frictional torque (p=0.016) with increased head size; increasing from 1.2 Nm to 1.5 Nm to 1.9 Nm for the 32mm, 48mm, and 56mm bearings respectively. The frictional torque significantly decreased when water was used compared to using new-born calf serum as lubricant. There was no significant difference in the frictional torque between all bearings sizes with water as lubricant, however, there was a trend of increased frictional torque with increased swing phase load. Changing the swing phase load had no influence on the frictional torques obtained for all bearing sizes when using 100% or 25% new-born calf serum. Under a steep inclination angle, the frictional torque for all bearing sizes did not significantly change compared to the flat cup condition. Discussion and Conclusion. The frictional torque tended to increase with increased head size. The highest frictional torque measured in this study was 2.5Nm for the 56mm ceramic-on-ceramic bearing (25% serum, steep cup) compared to 5.3Nm maximum torque measured using the same method for well-positioned and well lubricated 54mm metal-on-metal bearings. The frictional torque for all ceramic-on-ceramic bearing sizes (32mm, 48mm, and 56mm) decreased as the concentration of protein decreased. This was consistent with previous work done on 28mm bearings and the understanding that for ceramic-on-ceramic bearings the adherence of proteins to the surface reduces the effectiveness of lubricant film thickness, thus resulting in higher frictional torques due to the force required to shear the proteins

We have evaluated in vitro the accuracy of percutaneous and ultrasound registration as measured in terms of errors in rotation and version relative to the bony anterior pelvic plane in computer-assisted total hip replacement, and analysed the intra- and inter-observer reliability of manual or ultrasound registration.

Four clinicians were asked to perform registration of the landmarks of the anterior pelvic plane on two cadavers. Registration was performed under four different conditions of acquisition. Errors in rotation were not significant. Version errors were significant with percutaneous methods (16.2°; p < 0.001 and 19.25° with surgical draping; p < 0.001), but not with the ultrasound acquisition (6.2°, p = 0.13). Intra-observer repeatability was achieved for all the methods. Inter-observer analysis showed acceptable agreement in the sagittal but not in the frontal plane.

Ultrasound acquisition of the anterior pelvic plane was more reliable in vitro than the cutaneous digitisation currently used.

Objectives

The purpose of this study was to compare the results and complications of tibial lengthening over an intramedullary nail with treatment using the traditional Ilizarov method.

This review briefly summarises some of the definitive studies of articular cartilage by microscopic MRI (µMRI) that were conducted with the highest spatial resolutions. The article has four major sections. The first section introduces the cartilage tissue, MRI and µMRI, and the concept of image contrast in MRI. The second section describes the characteristic profiles of three relaxation times (T₁, T₂ and T_1ρ) and self-diffusion in healthy articular cartilage. The third section discusses several factors that can influence the visualisation of articular cartilage and the detection of cartilage lesion by MRI and µMRI. These factors include image resolution, image analysis strategies, visualisation of the total tissue, topographical variations of the tissue properties, surface fibril ambiguity, deformation of the articular cartilage, and cartilage lesion. The final section justifies the values of multidisciplinary imaging that correlates MRI with other technical modalities, such as optical imaging. Rather than an exhaustive review to capture all activities in the literature, the studies cited in this review are merely illustrative.

Wear of polyethylene is associated with aseptic loosening of orthopaedic implants and has been observed in hip and knee prostheses and anatomical implants for the shoulder. The reversed shoulder prostheses have not been assessed as yet. We investigated the volumetric polyethylene wear of the reversed and anatomical Aequalis shoulder prostheses using a mathematical musculoskeletal model. Movement and joint stability were achieved by EMG-controlled activation of the muscles. A non-constant wear factor was considered. Simulated activities of daily living were estimated from in vivo recorded data.

After one year of use, the volumetric wear was 8.4 mm³ for the anatomical prosthesis, but 44.6 mm³ for the reversed version. For the anatomical prosthesis the predictions for contact pressure and wear were consistent with biomechanical and clinical data. The abrasive wear of the polyethylene in reversed prostheses should not be underestimated, and further analysis, both experimental and clinical, is required.