Aims. To evaluate how abnormal proximal femoral anatomy affects different femoral version measurements in young patients with hip pain. Methods. First, femoral version was measured in 50 hips of symptomatic consecutively selected patients with hip pain (mean age 20 years (SD 6), 60% (n = 25) females) on preoperative CT scans using different measurement methods: Lee et al, Reikerås et al, Tomczak et al, and Murphy et al. Neck-shaft angle (NSA) and α angle were measured on coronal and radial CT images. Second, CT scans from three patients with femoral retroversion, normal femoral version, and anteversion were used to create 3D femur models, which were manipulated to generate models with different NSAs and different cam lesions, resulting in eight models per patient. Femoral version measurements were repeated on manipulated femora. Results. Comparing the different measurement methods for femoral version resulted in a maximum mean difference of 18° (95% CI 16 to 20) between the most proximal (Lee et al) and most distal (Murphy et al) methods. Higher differences in proximal and distal femoral version measurement techniques were seen in femora with greater femoral version (r > 0.46; p < 0.001) and greater NSA (r > 0.37; p = 0.008) between all measurement methods. In the parametric 3D manipulation analysis, differences in femoral version increased 11° and 9° in patients with high and normal femoral version, respectively, with increasing NSA (110° to 150°). Conclusion. Measurement of femoral version angles differ depending on the method used to almost 20°, which is in the range of the aimed surgical correction in derotational femoral osteotomy and thus can be considered clinically relevant. Differences between proximal and distal measurement methods further increase by increasing femoral version and NSA. Measurement methods that take the entire proximal femur into account by using distal landmarks may produce more sensitive measurements of these differences. Cite this article: Bone Jt Open 2022;3(10):759–766

Aims. Hip disease is common in children with cerebral palsy (CP) and can decrease quality of life and function. Surveillance programmes exist to improve outcomes by treating hip disease at an early stage using radiological surveillance. However, studies and surveillance programmes report different radiological outcomes, making it difficult to compare. We aimed to identify the most important radiological measurements and develop a core measurement set (CMS) for clinical practice, research, and surveillance programmes. Methods. A systematic review identified a list of measurements previously used in studies reporting radiological hip outcomes in children with CP. These measurements informed a two-round Delphi study, conducted among orthopaedic surgeons and specialist physiotherapists. Participants rated each measurement on a nine-point Likert scale (‘not important’ to ‘critically important’). A consensus meeting was held to finalize the CMS. Results. Overall, 14 distinct measurements were identified in the systematic review, with Reimer’s migration percentage being the most frequently reported. These measurements were presented over the two rounds of the Delphi process, along with two additional measurements that were suggested by participants. Ultimately, two measurements, Reimer’s migration percentage and femoral head-shaft angle, were included in the CMS. Conclusion. This use of a minimum standardized set of measurements has the potential to encourage uniformity across hip surveillance programmes, and may streamline the development of tools, such as artificial intelligence systems to automate the analysis in surveillance programmes. This core set should be the minimum requirement in clinical studies, allowing clinicians to add to this as needed, which will facilitate comparisons to be drawn between studies and future meta-analyses. Cite this article: Bone Jt Open 2023;4(11):825–831

Aims. To map the Oxford Knee Score (OKS) and High Activity Arthroplasty Score (HAAS) items to a common scale, and to investigate the psychometric properties of this new scale for the measurement of knee health. Methods. Patient-reported outcome measure (PROM) data measuring knee health were obtained from the NHS PROMs dataset and Total or Partial Knee Arthroplasty Trial (TOPKAT). Assumptions for common scale modelling were tested. A graded response model (fitted to OKS item responses in the NHS PROMs dataset) was used as an anchor to calibrate paired HAAS items from the TOPKAT dataset. Information curves for the combined OKS-HAAS model were plotted. Bland-Altman analysis was used to compare common scale scores derived from OKS and HAAS items. A conversion table was developed to map between HAAS, OKS, and the common scale. Results. We included 3,329 response sets from 528 patients undergoing knee arthroplasty. These generally met the assumptions of unidimensionality, monotonicity, local independence, and measurement invariance. The HAAS items provided more information than OKS items at high levels of knee health. Combining both instruments resulted in higher test-level information than either instrument alone. The mean error between common scale scores derived from the OKS and HAAS was 0.29 logits. Conclusion. The common scale allowed more precise measurement of knee health than use of either the OKS or HAAS individually. These techniques for mapping PROM instruments may be useful for the standardization of outcome reporting, and pooling results across studies that use either PROM in individual-patient meta-analysis. Cite this article: Bone Joint Res 2023;12(10):624–635

Aims. Hip dysplasia (HD) leads to premature osteoarthritis. Timely detection and correction of HD has been shown to improve pain, functional status, and hip longevity. Several time-consuming radiological measurements are currently used to confirm HD. An artificial intelligence (AI) software named HIPPO automatically locates anatomical landmarks on anteroposterior pelvis radiographs and performs the needed measurements. The primary aim of this study was to assess the reliability of this tool as compared to multi-reader evaluation in clinically proven cases of adult HD. The secondary aims were to assess the time savings achieved and evaluate inter-reader assessment. Methods. A consecutive preoperative sample of 130 HD patients (256 hips) was used. This cohort included 82.3% females (n = 107) and 17.7% males (n = 23) with median patient age of 28.6 years (interquartile range (IQR) 22.5 to 37.2). Three trained readers’ measurements were compared to AI outputs of lateral centre-edge angle (LCEA), caput-collum-diaphyseal (CCD) angle, pelvic obliquity, Tönnis angle, Sharp’s angle, and femoral head coverage. Intraclass correlation coefficients (ICC) and Bland-Altman analyses were obtained. Results. Among 256 hips with AI outputs, all six hip AI measurements were successfully obtained. The AI-reader correlations were generally good (ICC 0.60 to 0.74) to excellent (ICC > 0.75). There was lower agreement for CCD angle measurement. Most widely used measurements for HD diagnosis (LCEA and Tönnis angle) demonstrated good to excellent inter-method reliability (ICC 0.71 to 0.86 and 0.82 to 0.90, respectively). The median reading time for the three readers and AI was 212 (IQR 197 to 230), 131 (IQR 126 to 147), 734 (IQR 690 to 786), and 41 (IQR 38 to 44) seconds, respectively. Conclusion. This study showed that AI-based software demonstrated reliable radiological assessment of patients with HD with significant interpretation-related time savings. Cite this article: Bone Jt Open 2022;3(11):877–884

Aims. We aimed to assess the reliability and validity of OpenPose, a posture estimation algorithm, for measurement of knee range of motion after total knee arthroplasty (TKA), in comparison to radiography and goniometry. Methods. In this prospective observational study, we analyzed 35 primary TKAs (24 patients) for knee osteoarthritis. We measured the knee angles in flexion and extension using OpenPose, radiography, and goniometry. We assessed the test-retest reliability of each method using intraclass correlation coefficient (1,1). We evaluated the ability to estimate other measurement values from the OpenPose value using linear regression analysis. We used intraclass correlation coefficients (2,1) and Bland–Altman analyses to evaluate the agreement and error between radiography and the other measurements. Results. OpenPose had excellent test-retest reliability (intraclass correlation coefficient (1,1) = 1.000). The R. 2. of all regression models indicated large correlations (0.747 to 0.927). In the flexion position, the intraclass correlation coefficients (2,1) of OpenPose indicated excellent agreement (0.953) with radiography. In the extension position, the intraclass correlation coefficients (2,1) indicated good agreement of OpenPose and radiography (0.815) and moderate agreement of goniometry with radiography (0.593). OpenPose had no systematic error in the flexion position, and a 2.3° fixed error in the extension position, compared to radiography. Conclusion. OpenPose is a reliable and valid tool for measuring flexion and extension positions after TKA. It has better accuracy than goniometry, especially in the extension position. Accurate measurement values can be obtained with low error, high reproducibility, and no contact, independent of the examiner’s skills. Cite this article: Bone Joint Res 2023;12(5):313–320

Introduction. Total hip replacement (THR) is a very common procedure performed for the treatment of osteoarthritis of the hip. The aim of THR is to restore function and quality of life of the patients, by restoring femoral offset, leg length, centre of rotation, and achieving stability, to avoid dislocation postoperatively. Method. We aimed to perform preoperative assessment of femoral offset on anteroposterior (AP) radiographs of the hip, and on corresponding CT scans, for patients undergoing primary THR. Patients were positioned according to a standardised protocol prior to obtaining radiographs of the hip and CT scan. Inter- and intra-observer reliability was evaluated between 3 observers of differing levels of seniority – an orthopaedic trainee, a fellow, and a consultant. CT scan measurements of offset were performed by one consultant radiologist. The researchers measuring radiographic offset were blinded to the results of the CT measurements. Results. In the entire cohort of 50 patients, the mean femoral offset was 44 mm on AP radiographs of the hip and 45 mm on CT scans. No significant difference in mean femoral offset was seen between AP radiographs of the hip and CT. There was good inter and intra-observer reliability in the measurement of femoral offset on AP radiographs of the hip. There was no difference in the radiographic measurements between observers of differing levels of seniority. Conclusions. Accurate restoration of femoral offset is very important in the good functioning of THR. AP radiographs of the hip are accurate, and should be routinely obtained preoperatively for templating, prior to THR

Aims. The amount of glenoid bone loss is an important factor in deciding between soft-tissue and bony reconstruction when managing anterior shoulder instability. Accurate and reproducible measurement of glenoid bone loss is therefore vital in evaluation of shoulder instability and recommending specific treatment. The aim of this systematic review is to identify the range methods and measurement techniques employed in clinical studies treating glenoid bone loss. Methods. A systematic review of the PubMed, MEDLINE, and Embase databases was undertaken to cover a ten-year period from February 2011 to February 2021. We identified clinical studies that incorporated bone loss assessment in the methodology as part of the decision-making in the management of patients with anterior shoulder instability. The Preferred Reporting Items for Systematic Reviews (PRISMA) were used. Results. A total of 5,430 articles were identified from the initial search, of which 82 studies met the final inclusion criteria. A variety of imaging methods were used: three studies did not specify which modality was used, and a further 13 used CT or MRI interchangeably. There was considerable heterogeneity among the studies that specified the technique used to quantify glenoid bone loss. A large proportion of the studies did not specify the technique used. Conclusion. This systematic review has identified significant heterogeneity in both the imaging modality and method used to measure glenoid bone loss. The recommendation is that as a minimum for publication, authors should be required to reference the specific measurement technique used. Without this simple standardization, it is impossible to determine whether any published paper should influence clinical practice or should be dismissed. Cite this article: Bone Joint J 2022;104-B(1):12–18

The opposable thumb is one of the defining characteristics of human anatomy and is involved in most activities of daily life. Lack of optimal thumb motion results in pain, weakness, and decrease in quality of life. First carpometacarpal (CMC1) osteoarthritis (OA) is one of the most common sites of OA. Current clinical diagnosis and monitoring of CMC1 OA disease are primarily aided by X-ray radiography; however, many studies have reported discrepancies between radiographic evidence of CMC1 OA and patient-related outcomes of pain and disability. Radiographs lack soft-tissue contrast and are insufficient for the detection of early characteristics of OA such as synovitis, which play a key role in CMC OA disease progression. Magnetic resonance imaging (MRI) and two-dimensional ultrasound (2D-US) are alternative options that are excellent for imaging soft tissue pathology. However, MRI has high operating costs and long wait-times, while 2D-US is highly operator dependent and provides 2D images of 3D anatomical structures. Three-dimensional ultrasound imaging may be an option to address the clinical need for a rapid and safe point of care imaging device. The purpose of this research project is to validate the use of mechanically translated 3D-US in CMC OA patients to assess the measurement capabilities of the device in a clinically diverse population in comparison to MRI. Four CMC1-OA patients were scanned using the 3D-US device, which was attached to a Canon Aplio i700 US machine with a 14L5 linear transducer with a 10MHz operating frequency and 58mm. Complimentary MR images were acquired using a 3.0 T MRI system and LT 3D coronal photon dense cube fat suppression sequence was used. The volume of the synovium was segmented from both 3D-US and MR images by two raters and the measured volumes were compared to find volume percent differences. Paired sample t-test were used to determine any statistically significant differences between the volumetric measurements observed by the raters and in the measurements found using MRI vs. 3D-US. Interclass Correlation Coefficients were used to determine inter- and intra-rater reliability. The mean volume percent difference observed between the two raters for the 3D-US and MRI acquired synovial volumes was 1.77% and 4.76%, respectively. The smallest percent difference in volume found between raters was 0.91% and was from an MR image. A paired sample t-test demonstrated that there was no significant difference between the volumetric values observed between MRI and 3D-US. ICC values of 0.99 and 0.98 for 3D-US and MRI respectively, indicate that there was excellent inter-rater reliability between the two raters. A novel application of a 3D-US acquisition device was evaluated using a CMC OA patient population to determine its clinical feasibility and measurement capabilities in comparison to MRI. As this device is compatible with any commercially available ultrasound machine, it increases its accessibility and ease of use, while proving a method for overcoming some of the limitations associated with radiography, MRI, and 2DUS. 3DUS has the potential to provide clinicians with a tool to quantitatively measure and monitor OA progression at the patient's bedside

Aims. The aims of this study were to compare clinically relevant measurements of hip dysplasia on radiographs taken in the supine and standing position, and to compare Hip2Norm software and Picture Archiving and Communication System (PACS)-derived digital radiological measurements. Methods. Preoperative supine and standing radiographs of 36 consecutive patients (43 hips) who underwent periacetabular osteotomy surgery were retrospectively analyzed from a single-centre, two-surgeon cohort. Anterior coverage (AC), posterior coverage (PC), lateral centre-edge angle (LCEA), acetabular inclination (AI), sharp angle (SA), pelvic tilt (PT), retroversion index (RI), femoroepiphyseal acetabular roof (FEAR) index, femoroepiphyseal horizontal angle (FEHA), leg length discrepancy (LLD), and pelvic obliquity (PO) were analyzed using both Hip2Norm software and PACS-derived measurements where applicable. Results. Analysis of supine and standing radiographs resulted in significant variation for measurements of PT (p < 0.001) and AC (p = 0.005). The variation in PT correlated with the variation in AC in a limited number of patients (R. 2. = 0.378; p = 0.012). Conclusion. The significant variation in PT and AC between supine and standing radiographs suggests that it may benefit surgeons to have both radiographs when planning surgical correction of hip dysplasia. We also recommend using PACS-derived measurements of AI and SA due to the poor interobserver error on Hip2Norm. Cite this article: Bone Joint J 2021;103-B(11):1662–1668

Aims. Cross-table lateral (CTL) radiographs are commonly used to measure acetabular component anteversion after total hip arthroplasty (THA). The CTL measurements may differ by > 10° from CT scan measurements but the reasons for this discrepancy are poorly understood. Anteversion measurements from CTL radiographs and CT scans are compared to identify spinopelvic parameters predictive of inaccuracy. Methods. THA patients (n = 47; 27 males, 20 females; mean age 62.9 years (SD 6.95)) with preoperative spinopelvic mobility, radiological analysis, and postoperative CT scans were retrospectively reviewed. Acetabular component anteversion was measured on postoperative CTL radiographs and CT scans using 3D reconstructions of the pelvis. Two cohorts were identified based on a CTL-CT error of ≥ 10° (n = 11) or < 10° (n = 36). Spinopelvic mobility parameters were compared using independent-samples t-tests. Correlation between error and mobility parameters were assessed with Pearson’s coefficient. Results. Patients with CTL error > 10° (10° to 14°) had stiffer lumbar spines with less mean lumbar flexion (38.9°(SD 11.6°) vs 47.4° (SD 13.1°); p = 0.030), different sagittal balance measured by pelvic incidence-lumbar lordosis mismatch (5.9° (SD 18.8°) vs -1.7° (SD 9.8°); p = 0.042), more pelvic extension when seated (pelvic tilt -9.7° (SD 14.1°) vs -2.2° (SD 13.2°); p = 0.050), and greater change in pelvic tilt between supine and seated positions (12.6° (SD 12.1°) vs 4.7° (SD 12.5°); p = 0.036). The CTL measurement error showed a positive correlation with increased CTL anteversion (r = 0.5; p = 0.001), standing lordosis (r = 0.23; p = 0.050), seated lordosis (r = 0.4; p = 0.009), and pelvic tilt change between supine and step-up positions (r = 0.34; p = 0.010). Conclusion. Differences in spinopelvic mobility may explain the variability of acetabular anteversion measurements made on CTL radiographs. Patients with stiff spines and increased compensatory pelvic movement have less accurate measurements on CTL radiographs. Flexion of the contralateral hip is required to obtain clear CTL radiographs. In patients with lumbar stiffness, this movement may extend the pelvis and increase anteversion of the acetabulum on CTL views. Reliable analysis of acetabular component anteversion in this patient population may require advanced imaging with a CT scan. Cite this article: Bone Joint J 2021;103-B(7 Supple B):59–65

Introduction. Leg length discrepancy (LLD) is a common sequalae of limb reconstruction procedures. The subsequent biomechanical compensation can be directly linked to degenerative arthritis, lower back pain, scoliosis and functional impairment. It becomes particularly problematic when >2cm, established as a clinical standard. This two-arm experimental study assesses how reliable an iPhone application is in the measurement of LLD at different distances in control and LLD patients. Materials and Methods. 42 participants were included in the study, divided evenly into 21 control and 21 LLD patients. A standardised measurement technique was used to obtain TMM and iPhone application measurements, taken at a distance of 0.25m, 0.50m and 0.75m. Results. The mean discrepancy of iPhone-based measurements in the control group was 1.57cm, 1.59cm and 2.19cm at 0.25m, 0.50m and 0.75m respectively. This compares to measurements in the LLD cohort with a mean discrepancy of 1.71cm, 1.85cm and 2.19cm. The overall mean discrepancy of iPhone data was 1.78cm in the control cohort compared to 1.92cm in the LLD cohort. Conclusions. Results suggest that the iPhone application can be used to identify clinically significant leg length discrepancies. At 0.75 metres anomalous results become more prevalent and the accuracy of the application appears to decline. The results also suggest the application is slightly more accurate in the control group, nevertheless, in distances up to 0.50 metres the mean discrepancy sits within the 2cm standard of clinically significant LLD

Rotational laxity increases the risk of anterior cruciate ligament (ACL) injuries and residual rotational laxity can result in inferior surgical outcomes and risk of retears. The dynamic rotatory knee stability can be assessed through manual examination, but it is limited to the surgeon's experience and it provides inaccurate measurements, highlighting the need for objective measurement of knee rotational laxity. The objective measurement of knee laxity can help to better identify patients that may benefit from conservative treatment or those that require surgical treatment with or without concomitant extra-articular procedures. We rely in Porto Knee Testing Device (PKTD®) to accurately measure sagittal and rotatory laxity of the knee, either individually or in a combined fashion. The PKTD® is safe and can be used in combination with CT or MRI, which allows to assess both the “anatomy” and the “function” in the same examination. By this way, we may have a total ACL rupture and a stable knee not requiring surgery or, on the other hand, the same injury scenario but with an unstable knee that requires surgical intervention (with or without lateral extra-articular tenodesis). In cases of partial ACL tears, it may be possible to identify some ligamentous fibers that remain functional, where the conservative treatment or augmentation techniques can provide satisfactory results. It can also identify when a posteromedial or posterolateral instability is associated. The PKTD® can also be used to follow-up the laxity results of conservative and surgical procedures and contribute to the decision-making of return to sports

Gait measurements can vary due to various intrinsic and extrinsic factors, and this variability becomes more pronounced using inertial sensors in a free-living environment. Therefore, identifying and quantifying the sources of variability is essential to ensure measurement reliability and maintain data quality. This study aimed to determine the variability of daily accelerations recorded by an inertial sensor in a group of healthy individuals. Ten participants, four males and six females, with a mean age of 50 years (range: 29–61) and BMI of 26.9 kg/m. 2. (range: 21.4–36.8), were included. A single accelerometer continuously recorded lower limb accelerations over two weeks. We extracted and analyzed the accelerations of three consecutive strides within walking bouts if the time difference between the bouts was more than two hours. Multivariate mixed-effects modeling was performed on both the discretized acceleration waveforms at 101 points (0–100) and the harmonics of the signals in the frequency domain to determine the variance components for different subjects, days, bouts, and steps as the random effect variables. Intraclass correlation coefficients (ICCs) were calculated for between-day, between-bout, and between-step comparisons. The results showed that the ICCs for the between-day, between-bout, and between-step comparisons were 0.73, 0.82, 0.99 for the vertical axis; 0.64, 0.75, 0.99 for the anteroposterior axis; and 0.55, 0.96, 0.97 for the mediolateral axis. For the signal harmonics, the respective ICCs were 0.98, 0.98, 0.99 for the vertical axis; 0.54, 0.93, 0.98 for the anteroposterior axis; and 0.69, 0.78, 0.95 for the mediolateral axis. Overall, this study demonstrated that accelerations recorded continuously for multiple days in a free-living environment exhibit high variability, mainly between days, and some variability arising from differences between walking bouts during different times within days. However, reliable and repeatable gait measurements can be obtained by identifying and quantifying the sources of variability

The restoration of knee alignment is an important goal during total knee arthroplasty (TKA). In the past surgeons aimed to restore neutral limb alignment during surgery. However, previous studies have demonstrated alignment to be dynamic, varying depending on the position of the limb and the degree of weight-bearing, and between patients. We used a validated computer navigation system to measure the femorotibial mechanical angle (FTMA) in 264 knees in 77 male and 55 female healthy volunteers aged 18 to 35 years (mean 26.2). We found the mean supine alignment to be a varus angle of 1.2° (standard deviation (sd) 4), with few patients having neutral alignment. FTMA differs significantly between males and females (with a mean varus of 1.7° (sd 4) and 0.4° (sd 3.9), respectively; p = 0.008). It changes significantly with posture, the knee hyperextending by a mean of 5.6°, and coronal plane alignment becoming more varus by 2.2° (sd 3.6) on standing compared with supine.

Knee alignment is different in different individuals and is dynamic in nature, changing with different postures. This may have implications for the assessment of alignment in TKA, which is achieved in non-weight-bearing conditions and which may not represent the situation observed during weight-bearing.

Cite this article: Bone Joint J 2015; 97-B:498–502

Abstract. Objectives. Ultrasound speckle tracking is a safe and non-invasive diagnostic tool to measure soft tissue deformation and strain. In orthopaedics, it could have broad application to measure how injury or surgery affects muscle, tendon or ligament biomechanics. However, its application requires custom tuning of the speckle-tracking algorithm then validation against gold-standard reference data. Implementing an experiment to acquire these data takes months and is expensive, and therefore prohibits use for new applications. Here, we present an alternative optimisation approach that automatically finds suitable machine and algorithmic settings without requiring gold-standard reference data. Methods. The optimisation routine consisted of two steps. First, convergence of the displacement field was tested to exclude the settings that would not track the underlying tissue motion (e.g. frame rates that were too low). Second, repeatability was maximised through a surrogate optimisation scheme. All settings that could influence the strain calculation were included, ranging from acquisition settings to post-processing smoothing and filtering settings, totalling >1,000,000 combinations of settings. The optimisation criterion minimised the normalised standard deviation between strain maps of repeat measures. The optimisation approach was validated for the medial collateral ligament (MCL) with quasi-static testing on porcine joints (n=3), and dynamic testing on a cadaveric human knee (n=1, female, aged 49). Porcine joints were fully dissected except for the MCL and loaded in a material-testing machine (0 to 3% strain at 0.2 Hz), which was captured using both ultrasound (>14 repeats per specimen) and optical digital image correlation (DIC). For the human cadaveric knee (undissected), 3 repeat ultrasound acquisitions were taken at 18 different anterior/posterior positions over the MCL while the knee was extended/flexed between 0° and 90° in a knee extension rig. Simultaneous optical tracking recorded the position of the ultrasound transducer, knee kinematics and the MCL attachments (which were digitised under direct visualisation post testing). Half of the data collected was used for optimisation of the speckle tracking algorithms for the porcine and human MCLs separately, with the remaining unseen data used as a validation test set. Results. For the porcine MCLs, ultrasound strains closely matched DIC strains (R. 2. > 0.98, RMSE < 0.59%) (Figure 1A). For the human MCL (Figure 1B), ultrasound strains matched the strains estimated from the optically tracked displacements of the MCL attachments. Furthermore, strains developed during flexion were highly correlated with AP position (R = 0.94) with strains decreasing the further posterior the transducer was on the ligament. This is in line with previously reported length change values for the posterior, intermediate and anterior bundles of the MCL. Conclusions. Ultrasound speckle tracking algorithms can be adapted for new applications without ground-truth data by using an optimisation approach that verifies displacement field convergence then minimises variance between repeat measurements. This optimisation routine was insensitive to anatomical variation and loading conditions, working for both porcine and human MCLs, and for quasi-static and dynamic loading. This will facilitate research into changes in musculoskeletal tissue motion due to abnormalities or pathologies. Declaration of Interest. (a) fully declare any financial or other potential conflict of interest

Aim. Prosthetic joint infection (PJI) presents the second most common complication of total joint arthroplasty (TJA). Accumulating evidence suggests that up to 20% of aseptic failures are low-grade PJI. However, there is still no single test to reliably diagnose all PJI. In his thesis, Mazzucco emphasized the viscosity differences between normal, osteoarthritic, and rheumatic synovial fluid. Similarly, a recent study by Fu et al. reported significantly lower viscosity in patients with PJI compared to the aseptic failure cohort. The primary aim of our study was to determine whether synovial fluid viscosity is a more reliable diagnostic criterion for PJI compared to the synovial fluid cell count with differential and serum C-reactive protein (CRP) levels. Method. We prospectively analyzed the viscosity of synovial fluid samples obtained during TJA of hip and knee joint revision procedures. We sampled 2.5–5 mL of synovial fluid for viscosity measurement. The samples were centrifuged (4 min at 7000 rpm) and the resulting supernatant was immediately transferred into the Ostwald viscometer. Viscosity was derived from the time required for a given volume of synovial fluid to pass the viscometer at 20 °C. The synovial fluid samples were also analysed for their cell count with differential and serum CRP was measured. The definite diagnosis of PJI was established on basis of EBJIS criteria. For the viscosity, the threshold for detecting PJI was set at 65 seconds. Results. Between December 2020 and March 2021, we analyzed 12 knee and 11 hip TJA revision samples. These included 14 septic and 9 aseptic synovial fluid samples. The average viscometer time in the PJI group was 31s (range 20–48s) compared to 247s (range 68–616s) in the group of aseptic revision procedures. The specificity and sensitivity of our viscosity measurements were 100%. The sensitivity and specificity of cell count was 100% and 85.7%, for the synovial fluid differential they were 100% and 85.7%, and for the CRP they were 88.9% and 71.4%, respectively. Conclusions. Our study is the first to report a significant difference in synovial fluid viscosity between the PJI and the aseptic cohort. It points towards the diagnostic superiority of viscosity measurements over conventional synovial fluid cell count, synovial fluid differential, and serum CRP levels. Albeit currently limited by small sample size, the study remains ongoing

Aims. We quantitatively compared the 3D bone density distributions on CT scans performed on scaphoid waist fractures subacutely that went on to union or nonunion, and assessed whether 2D CT evaluations correlate with 3D bone density evaluations. Methods. We constructed 3D models from 17 scaphoid waist fracture CTs performed between four to 18 weeks after fracture that did not unite (nonunion group), 17 age-matched scaphoid waist fracture CTs that healed (union group), and 17 age-matched control CTs without injury (control group). We measured the 3D bone density for the distal and proximal fragments relative to the triquetrum bone density and compared findings among the three groups. We then performed bone density measurements using 2D CT and evaluated the correlation with 3D bone densities. We identified the optimal cutoff with diagnostic values of the 2D method to predict nonunion with receiver operating characteristic (ROC) curves. Results. In the nonunion group, both the distal (100.2%) and proximal (126.6%) fragments had a significantly higher bone density compared to the union (distal: 85.7%; proximal: 108.3%) or control groups (distal: 91.6%; proximal: 109.1%) using the 3D bone density measurement, which were statistically significant for all comparisons. 2D measurements were highly correlated to 3D bone density measurements (Spearman’s correlation coefficient (R) = 0.85 to 0.95). Using 2D measurements, ROC curve analysis revealed the optimal cutoffs of 90.8% and 116.3% for distal and proximal fragments. This led to a sensitivity of 1.00 if either cutoff is met and a specificity of 0.82 when both cutoffs are met. Conclusion. Using 3D modelling software, nonunions were found to exhibit bone density increases in both the distal and proximal fragments in CTs performed between four to 18 weeks after fracture during the course of treatment. 2D bone density measurements using standard CT scans correlate well with 3D models. In patients with scaphoid fractures, CT bone density measurements may be useful in predicting the likelihood of nonunion. Cite this article: Bone Joint J 2020;102-B(9):1200–1209

Introduction. Component position and overall limb alignment following Total Knee Arthroplasty (TKA) have been shown to influence device survivorship and clinical outcomes. However current methods for measuring post-operative alignment through 2D radiographs and CTs may be prone to inaccuracies due to variations in patient positioning, and certain anatomical configurations such as rotation and flexion contractures. The purpose of this paper is to develop a new vector based method for overall limb alignment and component position measurements using CT. The technique utilizes a new mathematical model to calculate prosthesis alignment from the coordinates of anatomical landmarks. The hypothesis is that the proposed technique demonstrated good accuracy to surgical plan, as well as low intra and inter-observer variability. Methods. This study received institutional review board approval. A total of 30 patients who underwent robotic assisted TKA (RATKA) at four different sites between March 2017 and January 2018 were enrolled in this prospective, multicenter, non-randomized clinical study. CT scans were performed prior to and 4–6 weeks post-operatively. Each subject was positioned headfirst supine with the legs in a neutral position and the knees at full extension. Three separate CT scans were performed at the anatomical location of the hip, knee, and ankle joint. Hip, knee, and ankle images were viewed in 3D software and the following vertices were generated using anatomical landmarks: Hip Center (HC), Medial Epicondyle Sulcus (MES), Lateral Epicondyle (LE), Femur Center (FC), Tibia Center (TC), Medial Malleolus (MM), Lateral Malleolus (LM), Femur Component Superior (FCS), Femur Component Inferior (FCI), Coronal Femoral Lateral (CFL), Coronal Femoral Medial (CFM), Coronal Tibia Lateral (CTL), and Coronal Tibia Medial (CTM). Limb alignment and component positions were calculated from these vertices using a new mathematical model. The measurements were compared to the surgeons’ operative plan and component targeted positions for accuracy analysis. Two analysts performed the same measurements separately for inter-observer variability analysis. One of the two analysts repeated the measurements at least 30 days apart to assess intra-observer variability. Correlation analysis was performed on the intra-observer analysis, while Bland Altman analysis was performed on the inter-observer analysis. Results. Average measurement errors of overall limb alignments, femoral and tibial component position were less than 1 degree. Bland Altman plots for inter-observer analysis demonstrate great reproducibility in limb and component alignment measurements between surgeons with no bias. Correlation plots for intra-observer analysis demonstrate low variability with slopes ranging between 0.86 to 1.00 and R value greater than 0.88. Discussion. The proposed method demonstrated good accuracy to plan and low intra- and inter observer variability. This technique may be considered for assessing component position accuracy with post-operative CTs. Further studies are needed to investigate the robustness of the method in a larger cohort. For any figures or tables, please contact authors directly

As treatments of knee osteoarthrosis are continually refined, increasingly sophisticated methods of evaluating their biomechanical function are required. Whilst TKA shows good preoperative pain relief and survivorship, functional outcomes are sub-optimal, and research focus has shifted towards their improvement. Restoration of physiological function is a common design goal that relies on clear, detailed descriptions of native biomechanics. Historical simplifications of true biomechanisms, for example sagittal plane approximation of knee kinematics, are becoming progressively less suitable for evaluation of new technologies. The patellar tendon moment arm (PTMA) is an example of such a metric of knee function that usefully informs design of knee arthroplasty but is not fully understood, in part due to limitations in its measurement. This research optimized PTMA measurement and identified the influence of knee size and sex on its variation. The PTMA about the instantaneous helical axis was calculated from optical tracked positional data. A fabricated knee model facilitated calculation optimization, comparing four data smoothing techniques (raw, Butterworth filtering, generalized cross-validated cubic spline-interpolation and combined filtering/interpolation). The PTMA was then measured for 24 fresh-frozen cadaveric knees, under physiologically based loading and extension rates. Sex differences in PTMA were assessed before and after size scaling. Large errors were measured for raw and interpolated-only techniques in the mid-range of extension, whilst both raw and filtered-only methods saw large inaccuracies at terminal extension and flexion. Combined filtering/interpolation enabled sub-mm PTMA calculation accuracy throughout the range of knee flexion, including at terminal extension/flexion (root-mean-squared error 0.2mm, max error 0.5mm) (Figure 1). Before scaling, mean PTMA throughout flexion was 46mm; mean, peak, and minimum PTMA values were larger in males, as was the PTMA at terminal flexion, the change in PTMA from terminal flexion to peak, and the change from peak to terminal extension (mean differences ranging from 5 to 10mm, p<0.05). Knee size was highly correlated with PTMA magnitude (r>0.8, p<0.001) (Figure 2). Scaling eliminated sex differences in PTMA magnitude, but peak PTMA occurred closer to terminal extension in females (female 15°, male 29°, p=0.01) (Figure 3). Improved measurement of the PTMA reveals previously undocumented characteristics that may help to improve the functional outcomes of knee arthroplasty. Knee size accounted for two-thirds of the variation in PTMA magnitude, but not the flexion angle at which peak PTMA occurred, which has implications for morphotype-specific arthroplasty and musculoskeletal models. The developed calculation framework is applicable both in vivo and vitro for accurate PTMA measurement and might be used to evaluate the relative performance of emerging technologies. For any figures or tables, please contact the authors directly

Foot pain and related problems are quite common in the community. It is reported that 24% of individuals older than 45 experienced foot pain. Also, it is stated that at least two thirds of individuals experiences moderate physical disability due to foot problems. In the absence of evaluation of risk factors such as limited ankle dorsiflexion in the early period of the diseases (Plantar fasciitis, Achilles Tendinopathy e.g.) and the lack of mobile systems with portable remote access, foot pain becomes refractory/chronic foot pain, secondary pathologies and ends with workload of 1., 2. and 3rd level healthcare services. In the literature, manuel and dijital methods have been used to analyze the ankle range of motion (ROM). These studies are generally based on placing protractors on the image and / or angle detection from inclination measurement by using the gyroscope sensor of the mobile device. Some of these applications are effective and they are designed to be suitable for measuring in a clinical setting by a physician or physiotherapist. To the best of our knowledge, there is no system developed to measure real-time ankle ROM remotely with collaboration of the patients. In this research, we proposed to develop an ankle ROM analyze system with smart phone application that can be used comfortably by subjects. We present a case of a 22-year-old male with a symptomatic pes planus. The mobile application, which was used for data collection, was designed and implemented for Android devices. Initially, before the mobile application home page is opened, a consent page was submitted to the acceptance of individual within the scope of Law (KVKK) data privacy. Then, the participant was asked to state his sociodemographic characteristics [age, gender, height, weight] and dominant side. No history of foot-ankle injury, trauma, and surgery was recorded. Activity pain of the foot was 6 according to visual anolog scale (VAS) in the mobile application. His ankle dorsiflexion was 15 ° by manuel goniometer. Besides, server was responsible for storing the collected data and ROM measurement. ROM was calculated by processing the foot video which was sent through the mobile application. During the processing phase, a segmentation model was used which was trained with image process and deep learning methods. With the developed system, we obtained the manual goniometric measurement result with 2 degrees deviation. As the application is calibrated, it is expected to approach the actual measurement of ROM. We can conclude that mobile app-goniometer result in dorsiflexion measurement is a novel promising evaluation method for ankle ROM. it will be easy and practical to detect and monitor risk factor of the diseases, decrease medical costs, provide health services in rural areas, and contribution to life quality and to reduce the workload on physicians and physiotherapist