Purpose of study. To determine the onset, incidence and associated symptoms of adverse noise emissions following total hip arthroplasty (THA) with ceramic-on-ceramic (CoC) bearing surfaces. Methods. 50 Sequential CoC THA's (45 patients) performed by a single surgeon were interviewed telephonically at an average post-operative period of 12 months. The same group was re-interviewed telephonically 12 months later. Patients who reported noise emissions at either interview were assessed clinically to determine if symptoms could be reproduced. Results. Of the 45 patients who underwent the first interview, 43 (48 THA's) were re- interviewed. 1 patient had died of an unrelated cause before the second interview, and 2 were not contactable. 2 patients (4%) reported noise emissions at the first interview and 8 (17%) at the second interview. 7 of these 8 patients reported a single or occasional sound. 1 patient reported regular noise emissions and she was the only patient who expressed concern about the noise. None of the patients reported pain or any other symptoms associated with the sound. In none of the cases could the noise be produced during clinical examination. The examiners were unable to demonstrate a correlation between reported noise emissions and radiographic assessment of component orientation. Discussion. When asked specifically about noise emissions, 17% of the patients in our series reported a noise. The majority of these patients (75%) reported no noises when interviewed initially (1 year following surgery), but did report noise emissions when re-interviewed a year later. The incidence as well as onset of reported noise emissions in our series correlates with those reported by other authors. NO DISCLOSURES

The problem associated with ceramic on ceramic total hip replacement (THR) is audible noise. Squeaking is the most frequently documented sound. The incidence of squeaking has been reported to wide range from 0.7 to 20.9%. Nevertheless there is no study to investigate on incidence of noise in computer assisted THR with ceramic on ceramic bearing. The purpose of this study was to determine the incidence and risks factors associated with noise. We retrospectively reviewed 200 patients (202 hips) whom performed computer assisted THR (Orthopilot, B. Braun, Tuttlingen, Germany) with ceramic on ceramic bearing between March 2009 and August 2012. All procedures underwent uncemented THR with posterior approach by single surgeon. All hips implanted with PLASMACUP and EXIA femoral stem (B. Braun, Tuttlingen, Germany). All cases used BIOLOX DELTA (Ceramtec, AG, Plochingen, Germany) ceramic liner and head. The incidence and type of noise were interviewed by telephone using set of questionnaire. Patient's age, weight, height, body mass index, acetabular cup size, femoral offset size determined from medical record for comparing between silent hips and noisy hips. The acetabular inclination angle, acetabular anteversion angle, femoral offset, hip offset were reviewed to compare difference between silent hips and noisy hips. The audible noise was reported for 13 hips (6.44%). 5 patients (5 hips) reported click (2.47%) and 8 patients (8 hips) squeaked (3.97%). The mean time to first occurrence of click was 13.4 months and squeak was 7.4 months after surgery. Most common frequency of click was less than weekly (60%) and squeak was 1–4 times per week (50%). Most common activity associated with noise was bending; 40% in click and 75% in squeaking. No patients complained for pain or social problem. Moreover, no patient underwent any intervention for the noise. The noise had not self-resolved in any of the patients at last follow up. Age, weight, height and BMI showed no statistically significant difference between silent hips and click hips. In addition, there was also same result between silent hips and squeaking hips. Acetabular cup insert size and femoral offset stem size the results showed that there was no statistically significant difference between silent hips and click hips, also with squeaking hips. Acetabular inclination, angle acetabular anteversion angle, femoral offset, hip offset the results shown that only acetabular anteversion angle differed significantly between silent hips (19.94±7.78 degree) and squeaking hips (13.46±5.54 degree). The results can conclude that incidence of noise after ceramic on ceramic THR with navigation was 6.44 %. Squeaking incidence was 3.97% and click incidence was 2.47%. The only associated squeaking risk factor was cup anteversion angle. In this study, squeaking hip had cup anteversion angle significant less than silent hip

Background/Purpose. Total hip arthroplasties (THAs) with ceramic bearings are widely performed in young, active patients and thus, long-term outcome in these population is important. Moreover, clinical implication of noise, in which most studies focused on ‘squeaking’, remains controversial and one of concerns unsolved associated with the use of ceramic bearings. However, there is little literature regarding the long-term outcomes after THAs using these contemporary ceramic bearings in young patients. Therefore, we performed a long-term study with a minimum follow-up of . 1. 5 years after THAs using contemporary ceramic bearings in young patients with osteonecrosis of the femoral head (ONFH) less than fifty. Materials and Methods. Among sixty patients (71 hips) with a mean age of 39.1 years, 7 patients (7 hips) died and 4 patients (4 hips) were lost before 15-year follow-up. The remaining 60 hips were included in this study with an average follow-up period of 16.3 years (range, 15 to 18). All patients underwent cementless THA using a prosthesis of identical design and a 28-mm third-generation alumina head by single surgeon. The clinical evaluations included the modified Harris hip score (HHS), history of dislocation and noise around the hip joint: Noise was classified into squeaking, clicking, grinding and popping and evaluated at each follow-up. Snapping was excluded through physical examination or ultrasonography. Radiographic analysis was performed regarding notching on the neck of femoral component, loosening and osteolysis. Ceramic fracture and survivorship free from revision were also evaluated. Results. The mean Harris hip score improved from 55.3 to 95.5 points (range, 83 to 100) at the time of the final follow-up. Seventeen patients (34.7%) reported noise around the hip joint: “squeaking” in one and “clicking” in 16 patients. Notching on the neck of femoral component suggesting impingement between neck and ceramic liner was demonstrated in 9 hips (15%) at average of 6.9 years postoperatively and located at 2 to 3.5 mm distal to edge of ceramic head. Although no chip fracture of ceramic ‘liner’ occurred, notching was associated with “clicking” sound (p<0.01). One patient who reported clicking sound underwent a revision THA because of ceramic ‘head’ fracture. Loosening, osteolysis or dislocation was not observed in any hip and survivorship free from revision at 5 years was 98%. Conclusion. Cementless THAs using 28-mm contemporary alumina ceramic head demonstrated excellent long-term outcome in young, active patients with ONFH. Despite this encouraging result, however, we remain concerned about ‘clicking’ sound, because we did observe it associated with notching on the neck of stem. Acknowledgement. This work was supported by Institute for Information & communications Technology Promotion (IITP) grant funded by the Korea government (MSIP) (#B0101-14-1081)

Monitoring the performance of hip replacements post-operatively is tedious and costly, necessitating radiological examinations as well as other specialized examinations such as whole blood metal ion levels. In an effort to control escalating costs, we conducted an ethically approved clinical trial to assess the efficacy of basic acoustic monitoring equipment to asses these implants. Method. An electronic stethoscope was successfully used to record sounds from the hips of participants with different bearing surfaces. The sounds were recorded while conducting a standardized movement sequence. A 5th order Savitzky-Golay filter with a window width of 21 points was used to remove background noise. The recordings were also listened to by ear and three primary classes of sounds were identified. Frequency components contained in the classes were identified using spectrograms and Welch power density spectra. The sounds were correlated with different patient factors including component positioning, BMI and length of time that the implant was in situ. The skewness and kurtosis of the power spectra were calculated and found to be different for each class. Further frequency analysis was conducted with the aid of the discrete wavelet transform. This met with some success as different frequency levels were found in each sound class. Results. All bearing surfaces produced some noise. The most sounds were produced by the ceramic-on-metal group, even though not in the audible range, and those participants with a body mass index in the obese range. Sounds were also detected in the ceramic-on-polyethylene implants. However, no consistent links between these factors and the sounds produced could be identified. Specifically, the lack of correlation between sound occurrence and length of implantation indicates that this technique is not useful in predicting possible failures or future complications in real time. Conclusions. The sounds themselves did not immediately reveal any information about the implants. This method was deemed impractical as a real-time diagnostic technique. Our study though has demonstrated that inexpensive acoustic monitoring devices can monitor noise emissions. Our data needs to be refined to make these investigations reliable and clinically relevant

Aim. While 16S rRNA PCR - Sanger sequencing has paved the way for the diagnosis of culture-negative bacterial infections, it does not provide the composition of polymicrobial infections. We aimed to evaluate the performance of the Nanopore-based 16S rRNA metagenomic approach using partial-length amplification of the gene, and to explore its feasibility and suitability as a routine diagnostic tool for bone and joint infections (BJI) in a clinical laboratory. Method. Sixty-two clinical samples from patients with BJI were sequenced on MinION* using the in-house partial amplification of the 16S rRNA gene. BJI were defined based on the ICM Philly 2018 and EBJIS 2021 criteria. Among the 62 samples, 16 (26%) were culture-positive, including 6 polymicrobial infections, and 46 (74%) were culture-negative from mono- and polymicrobial infections based on Sanger-sequencing. Contamination, background noise definition, bacterial identification, and time-effectiveness issues were addressed. Results. Results were obtained within one day. Setting a threshold at 1% of total reads overcame the background noise issue and eased interpretation of clinical samples. The partial 16S rRNA metagenomics approach had a greater sensitivity compared both to the culture method and the Sanger sequencing. All the 16 culture-positive samples were confirmed with the metagenomic sequencing. Bacterial DNA was detected in 32 culture-negative samples (70%), with pathogens consistent with BJI. The 14 Nanopore negative samples included 7 negative results confirmed after implementation of other molecular techniques and 7 false-negative MinION results: 3 Kingella kingae infections detected after targeted-PCR only, 2 Staphylococcus aureus infections and 2 Pseudomonas aeruginosa infections sterile on agar plate media and detected only after implementation of blood culture media, advocating for the very low inoculum. Conclusions. The results discriminated polymicrobial samples, and gave accurate bacterial identifications compared to Sanger-based results. They confirmed that Nanopore technology is user-friendly as well as cost- and time-effective. They also indicated that 16S rRNA targeted metagenomics is a suitable approach to be implemented for routine diagnosis of culture-negative samples in clinical laboratories. * Oxford Nanopore Technologies

Background. The accurate positioning of the total knee arthroplasty affects the survival of the implants(1). Alignment of the femoral component in relation to the native knee is best determined using pre- and post-operative 3D-CT reconstruction(2). Currently, the scans are visualised on separate displays. There is a high inter- and intra-observer variability in measurements of implant rotation and translation(3). Correct alignment is required to allow a direct comparison of the pre- and post-operative surfaces. This is prevented by the presence of the prostheses, the bone shape alteration around the implant, associated metal artefacts, and possibly a segmentation noise. Aim. Create a novel method to automatically register pre- and post-operative femora for the direct comparison of the implant and the native bone. Methods. The concept is to use post-operative femoral shaft segments free of metal noise and of surgical alteration for alignment with the pre-operative scan. It involves three steps. Firstly, using principal component analysis, the femoral shafts are re-oriented to match the X axis. Secondly, variants of the post-operative scan are created by subtracting 1mm increments from the distal femoral end (Fig1). Thirdly, an iterative closest point algorithm is applied to align the variants with the pre-operative scan. For exploratory validation, this algorithm was applied to a mesh representing the distal half of a 3D scanned femur. The mesh of a prosthesis was blended with the femur to create a post-operative model. To simulate a realistic environment, segmentation and metal artefact noise were added. For segmentation noise, each femoral vertex was translated randomly within +−1mm,+−2mm,+−3mm along its normal vector. To create metal artefact random noise was added within 50 mm of the implant points in the planes orthogonal to the shaft. The alignment error was considered as the average distance between corresponding points which are identical in pre- and post-operative femora. Results. Figure 2 shows, that when the implant zone is completely ignored, the error reaches a minimum plateau to below 1mm level. Different levels of segmentation noise had low impact on error value. Conclusions. These preliminary results obtained within a simulated environment show that by using only the native parts of the femur, the algorithm was able to automatically register the pre- and post-operative scans even in presence of the implant. Its application will allow visualisation of the scans on the same display for the direct comparison of the perioperative scans. This method requires further validation with more realistic noise models and with patient data. Future studies will have to determine if correct alignment has any effect on inter- and intra-observer variability. For figures, please contact authors directly.

Polyimide (MP-1, MMATech, Haifa, Israel), is a high performance aerospace thermoplastic used for its lubricity, stability, inertness and radiation resistance. A wear resistant thin robust bearing is needed for total hip arthroplasty (THR). After independent laboratory testing, in 2006, the author used the material as a bearing in two Reflection (Smith and Nephew, USA) hip surgeries. The first, a revision for polyethylene wear, survives with no evidence of wear, noise, new osteolysis or complications related to the MP-1 bearing after 16 yrs. The second donated his asymptomatic MP-1 hip at 6.5yrs for post-mortem examination. There were no osteoclasts, cellular reaction bland in contrast to that of polyethylene. In 2013 a clinical study with ethical committee approval was started using a Biolox Delta (Ceramtec, Germany) head against a polyimide liner in 97 patients. MMATech sold all liners, irradiated: steam 52:45. Sixteen were re-machined in New Zealand. Acetabular shells were Delta PF (LIMA, Italy). The liner locked by taper. The cohort consisted of 46:51 M:F, and ages 43 to 85, mean 65. Ten received cemented stems. For contralateral surgery, a ceramic or polyethylene liner was used. Initial patients were lower demand, later, more active patients, mountain-biking and running. All patients have on-going follow up, including MP-1 liner revision cases. There has been no measurable wear, or osteolysis around the acetabular components using weight-bearing radiographs. Squeaking within the first 6 weeks was noted in 39 number of cases and subtle increase in palpable friction, (passive rotation at 50 degrees flexion), but then disappeared. There were 6 revisions, four of which were related to cementless Stemsys implants (Evolutis, Italy) fixed distally with proximal linear lucencies in Gruen zones 1 and 7, and 2 and 6. No shells were revised and MP-1 liners were routinely changed to ceramic or polyethylene. The liners showed no head contact at the apex, with highly polished contact areas. There were no deep or superficial infections, but one traumatic anterior dislocation at 7 years associated with 5 mm subsidence of a non-collared stem. The initial squeaking and increased friction was due to the engineering of the liner / shell composite as implanted, not allowing adequate clearance for fluid film lubrication and contributed to by shell distortion during impaction. The revised bearings were “equatorial” rather than polar, and with lack of wear or creep this never fully resolved. Where the clearance was better, function was normal. The “slow” utilization was due to my ongoing concern with clearances not being correct. The revision of 4 Stemsys stems, tribology issues may have contributed, but non “MP-1” / Stemsys combinations outside this study have shown the same response, thought to be due to de-bonding of the hydroxyapatite coating. With correct engineering and clearances, a 3.6 mm thick MP-1 bearing, a surface Ra<0.5, steam sterilized, shows no appreciable wear, and with confidence, can be used as a high performance THR bearing

Accurate reconstruction of the knee pose from two X-Ray images will allow the study pre-operative kinematics (for custom prosthesis design) and the post-operative evaluation of the intervention. We used a SSM of the distal femur, based on 24 MRI datasets, from which the mean model and its modes of variation were defined. On the SSM, N landmarks in predefined positions were defined. The user identifies the same landmarks on two X-ray projections. Back-projecting the X-ray from the identified landmarks pixel to the corresponding source, each landmark position in the 3D space is reconstructed and the mean model pose initialised with a corresponding points registration. The silhouette of the SSM is projected on each X-ray image, which is automatically segmented in order to define the bone contours. With a Robust Point Matching algorithm based on Thin Plate Splines the projected silhouette points are deformed to better approximate the contour. For each contour point, the associated silhouette point is computed. We back-projected the ray from each contour point to the source and find on each ray the point with minimum distance to the silhouette. The cost function is the squared sum of the distances for both images. After a first optimisation of the pose, we perform a shape optimisation to find the correct weights for the SSM. To evaluate our algorithm, we used two Digitally Reconstructed Radiographs (DRR) created as projections at 90° from a CT dataset. The CT based model was reconstructed and the landmarks were defined on it with a rigid registration of the SSM. In order to validate the robustness of our reconstruction method, a random uniform noise distribution (0–50 mm on each direction) was added on each landmark. The reconstruction accuracy was measured as the distance between each reconstructed landmark and the ground truth defined on the CT. Results show that the population of the errors for the noise levels from 0 to 30 is similar: only the population with 50 mm noise is significantly different from the results obtained with other noise levels. We can conclude that with a noise level below 50 mm the algorithm is able to return the correct pose of the femur, while with higher noise the initial distribution of the landmarks in the 3D space prevents the correct outcome of the algorithm. The user should select the landmarks within a range of 50 mm on the 3D representation, that is half the dimension of the bounding box containing the model. We can assume that in the real case it will be more difficult to select the proper position of the landmarks, but our method proved to be robust even with misplaced landmarks

Neuromuscular scoliosis patients face rates of major complications of up to 49%. Along with pre-operative risk reduction strategies (including nutritional and bone health optimization), intra-operative strategies to decrease blood loss and decrease surgical time may help mitigate these risks. A major contributor to blood loss and surgical time is the insertion of instrumentation which is challenging in neuromuscular patient given their abnormal vertebral and pelvic anatomy. Standard pre-operative radiographs provide minimal information regarding pedicle diameter, length, blocks to pedicle entry (e.g. iliac crest overhang), or iliac crest orientation. To minimize blood loss and surgical time, we developed an “ultra-low dose” CT protocol without sedation for neuromuscular patients. Our prospective quality improvement study aimed to determine: if ultra-low dose CT without sedation was feasible given the movement disorders in this population; what the radiation exposure was compared to standard pre-operative imaging; whether the images allowed accurate assessment of the anatomy and intra-operative navigation given the ultra-low dose and potential movement during the scan. Fifteen non-ambulatory surgical patients with neuromuscular scoliosis received the standard spine XR and an ultra-low dose CT scan. Charts were reviewed for etiology of neuromuscular scoliosis and medical co-morbidities. The CT protocol was a high-speed, high-pitch, tube-current modulated acquisition at a fixed tube voltage. Adaptive statistical iterative reconstruction was applied to soft-tissue and bone kernels to mitigate noise. Radiation dose was quantified using reported dose indices (computed tomography dose index (CTDIvol) and dose-length product (DLP)) and effective dose (E), calculated through Monte-Carlo simulation. Statistical analysis was completed using a paired student's T-test (α = 0.05). CT image quality was assessed for its use in preoperative planning and intraoperative navigation using 7D Surgical System Spine Module (7D Surgical, Toronto, Canada). Eight males and seven females were included in the study. Their average age (14±2 years old), preoperative Cobb angle (95±21 degrees), and kyphosis (60±18 degrees) were recorded. One patient was unable to undergo the ultra-low dose CT protocol without sedation due to a co-diagnosis of severe autism. The average XR radiation dose was 0.5±0.3 mSv. Variability in radiographic dose was due to a wide range in patient size, positioning (supine, sitting), number of views, imaging technique and body habitus. Associated CT radiation metrics were CTDIvol = 0.46±0.14 mGy, DLP = 26.2±8.1 mGy.cm and E = 0.6±0.2 mSv. CT radiation variability was due to body habitus and arm orientation. The radiation dose differences between radiographic and CT imaging were not statistically significant. All CT scans had adequate quality for preoperative assessment of pedicle diameter and orientation, obstacles impeding pedicle entry, S2-Alar screw orientation, and intra-operative navigation. “Ultra-low dose” CT scans without sedation were feasible in paediatric patients with neuromuscular scoliosis. The effective dose was similar between the standard preoperative spinal XR and “ultra-low dose” CT scans. The “ultra-low dose” CT scan allowed accurate assessment of the anatomy, aided in pre-operative planning, and allowed intra-operative navigation despite the movement disorders in this patient population

Neuromuscular scoliosis patients face rates of major complications of up to 49%. Along with pre-operative risk reduction strategies (including nutritional and bone health optimization), intra-operative strategies to decrease blood loss and decrease surgical time may help mitigate these risks. A major contributor to blood loss and surgical time is the insertion of instrumentation which is challenging in neuromuscular patient given their abnormal vertebral and pelvic anatomy. Standard pre-operative radiographs provide minimal information regarding pedicle diameter, length, blocks to pedicle entry (e.g. iliac crest overhang), or iliac crest orientation. To minimize blood loss and surgical time, we developed an “ultra-low dose” CT protocol without sedation for neuromuscular patients. Our prospective quality improvement study aimed to determine:. if ultra-low dose CT without sedation was feasible given the movement disorders in this population;. what the radiation exposure was compared to standard pre-operative imaging;. whether the images allowed accurate assessment of the anatomy and intra-operative navigation given the ultra-low dose and potential movement during the scan. Fifteen non-ambulatory surgical patients with neuromuscular scoliosis received the standard spine XR and an ultra-low dose CT scan. Charts were reviewed for etiology of neuromuscular scoliosis and medical co-morbidities. The CT protocol was a high-speed, high-pitch, tube-current modulated acquisition at a fixed tube voltage. Adaptive statistical iterative reconstruction was applied to soft-tissue and bone kernels to mitigate noise. Radiation dose was quantified using reported dose indices (computed tomography dose index (CTDIvol) and dose-length product (DLP)) and effective dose (E), calculated through Monte-Carlo simulation. Statistical analysis was completed using a paired student's T-test (α= 0.05). CT image quality was assessed for its use in preoperative planning and intraoperative navigation using 7D Surgical System Spine Module (7D Surgical, Toronto, Canada). Eight males and seven females were included in the study. Their average age (14±2 years old), preoperative Cobb angle (95±21 degrees), and kyphosis (60±18 degrees) were recorded. One patient was unable to undergo the ultra-low dose CT protocol without sedation due to a co-diagnosis of severe autism. The average XR radiation dose was 0.5±0.3 mSv. Variability in radiographic dose was due to a wide range in patient size, positioning (supine, sitting), number of views, imaging technique and body habitus. Associated CT radiation metrics were CTDIvol = 0.46±0.14 mGy, DLP = 26.2±8.1 mGy.cm and E = 0.6±0.2 mSv. CT radiation variability was due to body habitus and arm orientation. The radiation dose differences between radiographic and CT imaging were not statistically significant. All CT scans had adequate quality for preoperative assessment of pedicle diameter and orientation, obstacles impeding pedicle entry, S2-Alar screw orientation, and intra-operative navigation. “Ultra-low dose” CT scans without sedation were feasible in paediatric patients with neuromuscular scoliosis. The effective dose was similar between the standard preoperative spinal XR and “ultra-low dose” CT scans. The “ultra-low dose” CT scan allowed accurate assessment of the anatomy, aided in pre-operative planning, and allowed intra-operative navigation despite the movement disorders in this patient population

Purpose. To achieve 3D kinematic analysis of total knee arthroplasty (TKA), 2D/3D registration techniques, which use X-ray fluoroscopic images and computer-aided design model of the knee implants, have been applied to clinical cases. In previous feature-based registration methods, only edge contours originated from knee implants are assumed to be extracted from X-ray images before 2D/3D registration. Due to the influence of bone and bone-cement close to knee implants, however, edge detection methods extract unwanted spurious edges and noises in clinical images. Thus, time-consuming and labor-intensive manual operations are often necessary to remove the unwanted edges. It has been a serious problem for clinical applications, and there is a strong demand for development of improved method. The purpose of this study was to develop a pose estimation method to perform accurate 2D/3D registration even if spurious edges and noises exist in knee images. Methods. Our 2D/3D registration technique is based on a feature-based algorithm, and contour points from X-ray images are extracted by Gaussian Laplacian filter and zero crossing methods. The basic principle of the algorithm is that the 3D pose of a model can be determined by projecting rays from contour points in an image back to the X-ray focus and noting that all of these rays are tangential to the model surface. Therefore, 3D poses are estimated by minimizing the sum of Euclidean distances between all projected rays and the model surface. Additionally, we introduce robust statistics into the 3D pose estimation method to perform accurate 2D/3D registration even if spurious edges and noises exist in knee images. The robust estimation method employs weight functions to reduce the influence of spurious edges and noises. The weight functions are defined for each contour point, and optimization is performed after the weight functions are multiplied to a cost function. Experimental results. The accuracy and stability validation were performed using in vivo images. The effects of robust estimation were evaluated by comparison with non-robust estimation. One image contained spurious edges and noises, and the other image didn't (they were erased manually). We applied robust and non-robust methods to each image (300 frames). As correct poses, we used the poses which were got by applying previous method to the contour images which spurious edges and noises didn't exist. The root mean square errors (RMSE) and success rate were calculated, and the success rate was defined as the rate of satisfying clinical required accuracy (error is less than 1mm, 1 degree). As results of the experiments, when non-robust method was applied to contour images in which spurious edges and noises exist, RMSE was too large and success rate was 0 %. However, when robust method was applied to the same images, RMSE was less than 1 mm, 1 degree, and the success rate was about 60 percent. Fig. 1 shows typical result of the experiment. Conclusions. We have developed a robust 3D kinematic estimation method of TKA from X-ray images, and the method was found to be helpful for analyzing TKA kinematics without labor-intensive operations

Overall, hip and knee total joint replacement (TJR) patients experience marked benefit, with reported satisfaction rates of greater than 80% with regard to pain relief and improved function. However, many patients experience ‘nuisance’ symptoms, an annoyance which may cause discomfort, which can negatively impact postoperative satisfaction. The purpose of this study was to evaluate the prevalence of nuisance symptoms among TJR patients and impact on overall patient satisfaction. A prospective survey study to assess type and prevalence of primary hip/knee TJR related nuisance symptoms, and impact on patient satisfaction at six-months to one-year post-TJR was conducted. The survey was administered over a one-year period at one academic arthroplasty centre. Survey questions tapped occurrence of commonly reported nuisance symptoms (e.g. localized pain, swelling, stability, incision appearance/numbness, stiffness, clicking/noise, ability to perform activities of daily living), and impact of the symptom on overall hip/knee satisfaction rated on a 10-point visual analogue scale (VAS), (0=no impact, 10=to a great extent). Overall VAS satisfaction with TJR was also assessed (0=not at all satisfied, 10=extremely satisfied). Survey responses were analysed using descriptive statistics. The sample comprised of 974 primary TJR patients, including 590 knees (61%) and 384 hips 39%) who underwent surgery over a one-year period. Among knees, the most commonly reported nuisance symptoms and associated impact to satisfaction per mean VAS scores included: difficulty kneeling (78.2%, mean VAS 4.3, ±3.3), limited ability to run or jump (71.6%, VAS 3.3, ±3.3), numbness around incision (46.3%, VAS 3.8, ±3.3), clicking/noise from the knee (44.2%, VAS 2.7, ±2.7) and stiffness (43.3%, 3.3, ±2.7) following knee arthroplasty. Overall, 88.1% of knee patients surveyed experienced at least one self-reported nuisance symptom at one-year postoperative. Mean overall VAS satisfaction with knee TJR was reported as 9/10 (±1.7). Among hip TJR patients, the most commonly reported nuisance symptoms and associated impact to satisfaction per VAS scores were: limited ability to run or jump (68.6%, VAS 3.4, ±3.4), muscular pain in the thigh (44.8%, VAS 3 ±2.7), limp when walking (37.6%, VAS 4.1, ±3.2), hip stiffness (31%, VAS 3.1, ±2.4), and new or worsening low back pain (24.3%, VAS 2.9, ±2.5). Overall, 93.7% of patients experienced at least one self-reported nuisance symptom at one-year postoperative. Mean overall VAS satisfaction following total hip arthroplasty at one year was reported as 8.9/10 (±1.7). Nuisance symptoms following primary total hip and knee arthroplasty are very common. Despite the high prevalence of such symptoms, impact of individual symptoms to overall TJR satisfaction is minimal and overall TJR patient satisfaction remains high. Careful preoperative counselling regarding the prevalence of such symptoms is prudent and will help establish realistic expectations following primary hip and knee TJR

INTRODUCTION. Squeaking after total hip replacement has been reported in up to 10% of patients. Some authors proposed that sound emissions from squeaking hips result from resonance of one or other or both of the metal parts and not the bearing surfaces. There is no reported in vitro study about the squeaking frequencies under lubricated regime. The goal of the study was to reproduce the squeaking in vitro under lubricated conditions, and to compare the in vitro frequencies to in vivo frequencies determined in a group of squeaking patients. The frequencies may help determining the responsible part of the noise. METHODS. Four patients, who underwent THR with a Ceramic-on-Ceramic THR (Trident(r), Stryker(r)) presented a squeaking noise. The noise was recorded and analysed with acoustic software (FMaster(r)). In-vitro 3 alumina ceramic (Biolox Forte Ceramtec(r)) 32 mm diameter (Ceramconcept(r)) components were tested using a PROSIM(r) hip friction simulator. The cup was positioned with a 75° abduction angle in order to achieve edge loading conditions. The backing and the cup liner were cut with a diamond saw, in order to avoid neck-head impingement and dislocation in case of high cup abduction angles (Figure1). The head was articulated ± 10° at 1 Hz with a load of 2.5kN for a duration of 300 cycles. The motion was along the edge. Tests were conducted under lubricated conditions with 25% bovine serum without and with the addition of a 3. rd. body alumina ceramic particle (200 μm thickness and 2 mm length). Before hand, engineering blue was used in order to analyze the contact area and to determine whether edge loading was achieved. RESULTS. Edge loading was obtained. In-vitro, no squeaking occurred under edge loading conditions. However, with the addition of an alumina ceramic 3. rd. body particle in the contact region squeaking was obtained at the beginning of the tests and stopped after ∼20 seconds (dominant frequency 2.6 kHz). In-vivo, recordings had a dominant frequency ranging between 2.2 and 2.4 kHz. DISCUSSION. For the first time, squeaking was reproduced in vitro under lubricated conditions. In-vitro noises followed edge loading and 3. rd. body particles and despite, the severe conditions, squeaking was intermittent and difficult to reproduce. However, squeaking is probably more difficult to reproduce because the cup was cut and the head was fixed in the simulator, preventing vibration to occur. Squeaking noises of a similar frequency were recorded in-vitro and in-vivo. The lower frequency of squeaking recorded in-vivo, demonstrates a potential damping effect of the soft tissues. Therefore, the squeaking in the patients was probably related to the bearing surfaces and modified lubrication conditions that may be due to edge loading. Varnum et al reported recently (3) that all the revised squeaking patients had a neck-cup impingement with metal 3. rd. body particles. These metallic wear particles may generate squeaking as shown in vitro. However, a larger cohort of squeaking patients is needed to confirm these results

Background. Theoretically, improved material properties of new alumina matrix composite (AMC) material, Delta ceramics, are expected to decrease concerns associated with pure alumina ceramics and allow manufacturing thinner liners and consequent larger heads. However, limited short-term clinical results are available and mid-term results of these effects are unclear. Questions/Purposes. (1) Does AMC material decrease the rate of ceramic fracture and noise, concerns of previous-generation ceramics, following change of material properties? (2) Does the possible use of larger heads consequent to manufacturing thinner liners decrease dislocation rate and affect inguinal pain? (3) Do any other complications associated with the use of AMC ceramics occur?. Materials and Methods. One-hundred cementless primary total hip arthroplasties (THAs) using AMC ceramic bearings were performed consecutively by single surgeon. The mean follow-up period was 5.4 years (range, 5.0 to 5.7) and average age at the time of arthroplasty was 54.7 years. Prostheses with identical design and Biolox® Delta ceramics were used in all patients. Clinical evaluation included the occurrence of inguinal pain and noise which was classified into squeaking, clicking, grinding and popping. Ceramic fracture, dislocation and any other complications associated with the use of AMC ceramics were also investigated. Result. No ceramic fracture occurred and noise was reported in three patients (3.2%); three subjective clicking, but no squeaking. Single event of perioperative dislocation due to incompliance occurred in one hip (1.1%) and inguinal pain was reported in two hips (2.1 %); neither evidence of iliopsoas tendinitis on ultrasonography, nor association with ceramic head size (p>0.05). Liner dissociation following initial square seating was shown immediately after surgery in one hip (1.1%) and underwent revision THA. Conclusion. Improved material properties combined with the possible use of larger-diameter head make AMC ceramics a promising alternative bearing option with reduced risk of ceramic fracture, squeaking and dislocation. In spite of these encouraging results, however, meticulous technical precautions such as square seating and proper impaction in particular, should be taken during whole process of liner insertion

Functional approaches for the localisation of the hip centre (HC) are widely used in Computer Assisted Orthopedic Surgery (CAOS). These methods aim to compute the HC defined as the centre of rotation (CoR) of the femur with respect to the pelvis. The Least-Moving-Point (LMP) method is one approach which consists in detecting the point that moves the least during the circumduction motion. The goal of this paper is to highlight the limits of the native LMP (nLMP) and to propose a modified version (mLMP). A software application has been developed allowing the simulation of a circumduction motion of a hip in order to generate the required data for the computation of the HC. Two tests have been defined in order to assess and compare both LMP methods with respect to (1) the camera noise (CN) and (2) the acetabular noise (AN). The mLMP and nLMP error is respectively: (1) 0.5±0.2mm and 9.3±1.4mm for a low CN, 21.7±3.6mm and 184.7±13.1mm for a high CN, and (2) 2.2±1.2mm and 0.5±0.3mm for a low AN, 35.2±18.5mm and 13.0±8.2mm for a high AN. In conclusion, mLMP is more robust and accurate than the nLMP algorithm

Purpose. The fourth generation ceramic, in which zirconia is incorporated into the alumina matrix, was developed to reduce the risk of ceramic fractures. The purpose of this study was to evaluate the survivorship, clinical and radiographic results, and bearing-related failures associated with total hip arthroplasty using zirconia-toughened alumina ceramic-on-ceramic bearings over a minimum follow-up of 5 years. Materials and methods. We retrospectively analysed 135 patients (151 hips) who underwent cementless total hip arthroplasty using zirconia-toughened alumina ceramic-on-ceramic bearings. There were 58 men and 77 women with mean age of 55.9 years (range, 20 to 82 years) at index surgery. Acetabular and femoral components were cementless in all hips. A 36 mm head was used in 81 of 151 hips and a 32 mm head was used in 70 hips with smaller acetabular shells. The mean duration of follow-up was 6.1 years (range, 5 to 6.8 years). Results. Kaplan-Meier survival analysis with an end point of revision for any reason was 100% at 6.8 years. All acetabular and femoral components showed bony ingrowth. No radiographic evidence of osteolysis was identified. No ceramic fracture occurred. There were 4 (2.6%) noisy hips (1 squeaking and 3 clickings), but no patient could reproduce the noise and required revision. Other complications included one iliopsoas tendonitis and one dislocation. Conclusions. The minimum 5-year results of total hip arthroplasties performed using 32 mm or 36 mm zirconia-toughened alumina ceramic-on-ceramic bearings were encouraging with excellent survivorship. However, it was also found that the risk of noise development remains even for the newest generation of ceramics

INTRODUCTION. Osteoarthritis (OA) is a growing societal burden, due to the ageing population. Less invasive, less damaging, and cheaper methods for diagnosis are needed, and sound technology is an emerging tool in this field. Some studies investigate ultrasound signals, while others look at acoustic signals in the audible range. AIMS. The aim of the current research was to: 1) investigate the potential of visual scalogram analysis of Acoustic Emission (AE) frequencies within the human audible range (20–20000 Hz) to diagnose knee OA, 2) correlate the qualitative visual scalogram analysis of the AE with OA symptoms, and 3) to do this based on information gathered during gait. METHODS. The analysis was carried out on a database collected during a prospective sound study on healthy and osteoarthritic knees. Sound recordings obtained with a contact microphone mounted on the patella and attached to a digital pre-amplifier, whilst patients were walking on a treadmill, were visualised, manually sampled, and transformed into scalograms. Features of the scalograms were described and qualitatively analysed through chi-squared tests for association with healthy or OA knees (knee status), and with severity of OA pain and functional symptoms and impact on quality of life (QoL), activities of daily living (ADL) and sports using the Knee Injury and Osteoarthritis Outcome Score (KOOS) subscales. RESULTS. 28 patients (56 knees) were included in the analysis. Our method provides a wide variety of different scalogram features: if no events were recorded, the scalogram was classified as ‘quiet’ (Fig 1). In case of abnormal recordings, data analysis evaluated association with the total count of the three most common events that appeared: 1. Peak (Fig 2), 2. Scattered (Fig 3) or 3. Island (localized noise but not presenting as a peak) (Fig 4) – “scalogram features”. No association was found between global scalogram characteristics (quiet versus ‘any noise’) and knee status (healthy or OA) (χ. 2. =3.163, p=0.075), but was found between knee status and three specific scalogram features (χ. 2. =9.743, p=0.008). The strongest association was a higher frequency of the “scattered” feature in the OA group (χ. 2. =9.06, p=0.01). Scalogram characteristics had no significant association with the sports and recreation (χ. 2. =1.74, p=0.419) nor the activities of daily living (χ. 2. =1.80, p=0.406) KOOS subscales. Significant association was found between scalogram characteristic and the pain (χ. 2. =10.34, p=0.006), quality of life (χ. 2. =6.58, p=0.037), and symptoms (χ. 2. =7.54, p=0.023) subscales. CONCLUSION. Promising results from analysis of individual features and of KOOS subscales establish the potential of acoustic analysis in evaluation of OA knees. More analysis of the data is needed to better define the variety of scalogram features. The future consequences of this research would be the development of a fast and affordable, non-invasive, radiation-free and potentially portable approach to evaluation, diagnosis and longitudinal monitoring of knee disorders. For any figures or tables, please contact the authors directly

Objectives. Articular cartilage damage is a primary outcome of pre-clinical and clinical studies evaluating meniscal and cartilage repair or replacement techniques. Recent studies have quantitatively characterized India Ink stained cartilage damage through light reflectance and the application of local or global thresholds. We develop a method for the quantitative characterisation of inked cartilage damage with improved generalisation capability, and compare its performance to the threshold-based baseline approach against gold standard labels. Methods. The Trainable WEKA Segmentation (TWS) tool (Arganda-Carreras et al., 2017) available in Fiji (Rueden et al., 2017) was used to train two separate Random Forest classifiers to automatically segment cartilage damage on ink stained cadaveric ovine stifle joints. Gold standard labels were manually annotated for the training, validation and test datasets for each of the femoral and tibial classifiers. Each dataset included a sample of medial and lateral femoral condyles and tibial plateaus from various stifle joints, selected to ensure no overlap across datasets according to ovine identifier. Training was performed on the training data with the TWS tool using edge, texture and noise reduction filters selected for their suitability and performance. The two trained classifiers were then applied to the validation data to output damage probability maps, on which a threshold value was calibrated. Model predictions on the unseen test set were evaluated against the gold standard labels using the Dice Similarity Coefficient (DSC) – an overlap-based metric, and compared with results for the baseline global threshold approach applied in Fiji as shown in Figures 1 and 2. Results. Test set results for the global threshold approach against gold standard labels were 45.0% DSC for the femoral condyle and 32.0% DSC for the tibial plateau. Results for the developed TWS classifiers on the same unseen test data were 79.0% and 72.7% DSC, showing absolute gains of 34.0% and 40.7% DSC over the global threshold baseline for the femoral and tibial classifiers. The trained TWS classifiers were then applied to an external set of unlabelled images of ink stained femoral condyles and tibial plateaus. Model results on sample images shown in Figure 3 further highlight the generalisation capability of the developed models. The most prominent classification features were Hessian filters (32.9%), Entropy (19.4%), Gaussian blur (10.1%), Gabor filters (6.3%) and Sobel filters (6.0%), with all other features contributing less than 6%. Conclusions. Our findings show that the developed segmentation method more accurately quantifies cartilage damage and provides improved generalisation capability over a range of input variations such as inconsistent orientation and lighting conditions. The developed model enables the use of articular cartilage damage as a reliable and quantitative outcome measure in studies involving large datasets, with reduced requirements for complex pre-processing and specialised equipment. For any figures or tables, please contact the authors directly

Purpose. For 3D kinematic analysis of total knee arthroplasty (TKA), 2D/3D registration techniques which use X-ray fluoroscopic images and computer-aided design model of the knee implants, have been applied to clinical cases. These techniques are highly valuable for dynamic 3D kinematic analysis, but have needed time-consuming and labor-intensive manual operations in some process. In previous study, we reported a robust method to reduce manual operations to remove spurious edges and noises in edge detection process of X-ray images. In this study, we address another manual operations problem occurred when setting initial pose of TKA implants model for 2D/3D registration. To set appropriate initial pose of the model with manual operations for each X-ray image is important to obtain the good registration results. However, the number of X-ray images for a knee performance is very large, and thus to set initial pose with manual operations is very time-consuming and a problem for practical clinical applications. Therefore, this study proposes an initial pose estimation method for automated 3D kinematic analysis of TKA. Methods. 3D pose of an implant model is estimated using a 2D/3D registration technique based on a robust feature-based algorithm. To reduce labor-intensive manual operations of initial pose setting for large number of X-ray images, we utilize an interpolation technique with an approximate function. First, for some X-ray images (key frames), initial poses are manually adjusted to be as close as possible, and 3D poses of the model are accurately estimated for each key frame. These key frames were appropriately selected from the 2D feature point of knee motion in the X-ray images. Next, the 3D pose data estimated for each key frame are interpolated with an approximate function. In this study, we employed a multilevel B-spline function. Thus, we semi-automatically estimate the initial 3D pose of the implant model in X-ray images except for key frames. Fig. 1 shows the algorithm of initial pose estimation, and Fig. 2 shows the scheme of the data interpolation with an approximate function. Experimental results. To validate the feasibility of the proposed initial pose estimation method, experiments using X-ray fluoroscopic images of 8 TKA patients during knee motions were performed. For the experiments, we prepared two sorts of contour images, and applied the proposed method to the one image contained spurious edges and noises. The other image which spurious edges and noises didn't exist was used for determination of correct poses (reference data) using 2D/3D registration. In order to assess the performance of the proposed method, automation rate was calculated, and the rate was defined as the X-ray frame number of satisfying clinical required accuracy (error within 1 mm, 1 degree) relative to all X-ray frame number. As results of the experiments, the automation rate of the femoral and tibial component were about 79 % and 73 %, respectively. Conclusions. This study presented an initial pose estimation method for automated 3D kinematic analysis of TKA using X-ray fluoroscopic images. The method without labor-intensive operations is thought to be very useful for practical clinical applications

Introduction. Modern ceramic-on-ceramic bearings have become attractive alternatives to conventional polyethylene due to their low wear and minimal particle production. However, ceramic-on-ceramic implants have been associated with ceramic fracture and squeaking. To address these issues, large ceramic heads with a titanium-alloy sleeve have been introduced although limited data are available on their clinical outcomes. The purpose of this study was to report the midterm results of primary total hip arthroplasty using a 32mm with a titanium-alloy sleeve. Materials & Methods. We reviewed 245 patients who had 274 total hip arthroplasties with a 32 mm ceramic head with a titanium-alloy sleeve and had been followed for more than 5 years (average, 6.5 years; range, 5–9 years). The mean patient age at the time of surgery was 55.1 years (range, 16–82 years). All operations were performed at a single center. All of the ceramic implants were hot isostatic pressed, laser-marked, proof-tested third-generation alumina (Fig. 1). We determined the implant survival, Harris hip scores, incidence of ceramic fracture or noisy hips, and presence of osteolysis. Results. The survival rate of ceramic-on-ceramic bearings in primary total hip arthroplasty using 32 mm ceramic head with titanium-alloy sleeve was 97.5% at 9 years (Fig. 2). The Harris hip score improved from mean of 47 preoperatively to 93 at last follow-up. One ceramic head fractured at 6 years postoperatively. No ceramic liners were seen to fracture. Audible hip noise was identified in five hips (1.8%); clicking in four and squeaking in one. Osteolysis was detected in four hips (1.5%), but all had no symptom (Fig. 3). Other complications included three deep infections, two dislocations, and one peroneal nerve palsy. Conclusions. Primary ceramic-on-ceramic total hip arthroplasty using a 32 mm ceramic head with a titanium-alloy sleeve has a high survival rate of 97.5% at a 9-year follow-up. Nevertheless, surgeons should be aware of the potential risks of ceramic fracture, noise, and osteolysis associated with the use of ceramic head with a titanium-alloy sleeve