Aims. Current levels of hip fracture morbidity contribute greatly to the overall burden on health and social care services. Given the anticipated ageing of the population over the coming decade, there is potential for this burden to increase further, although the exact scale of impact has not been identified in contemporary literature. We therefore set out to predict the future incidence of hip fracture and help inform appropriate service provision to maintain an adequate standard of care. Methods. Historical data from the Scottish Hip Fracture Audit (2017 to 2021) were used to identify monthly incidence rates. Established time series forecasting techniques (Exponential Smoothing and Autoregressive Integrated Moving Average) were then used to predict the annual number of hip fractures from 2022 to 2029, including adjustment for predicted changes in national population demographics. Predicted differences in service-level outcomes (length of stay and discharge destination) were analyzed, including the associated financial cost of any changes. Results. Between 2017 and 2021, the number of annual hip fractures increased from 6,675 to 7,797 (15%), with a rise in incidence from 313 to 350 per 100,000 (11%) for the at-risk population. By 2029, a combined average projection forecast the annual number of hip fractures at 10,311, with an incidence rate of 463 per 100,000, representing a 32% increase from 2021. Based upon these projections, assuming discharge rates remain constant, the total overall length of hospital stay following hip fracture in Scotland will increase by 60,699 days per annum, incurring an additional cost of at least £25 million per year. Approximately five more acute hip fracture beds may be required per hospital to accommodate this increased activity. Conclusion. Projection modelling demonstrates that hip fracture burden and incidence will increase substantially by 2029, driven by an ageing population, with substantial implications for health and social care services. Cite this article: Bone Joint J 2024;106-B(1):62–68

Fractures of the clavicle are relatively common, occurring mostly in younger patients and have historically been managed non-operatively. Recent studies have shown an advantage to surgical reduction and stabilisation of clavicle fractures with significant displacement. Currently, fracture displacement is measured using simple anterior-posterior two-dimensional x-rays of the clavicle. Since displacement can occur in all three-dimensions, however, evaluation of the amount displacement can be difficult and inaccurate. The purpose of this study was to determine the view that provides the most accurate assessment. Nine CT scans of acute displaced clavicle fractures were analysed with AmiraDEV5.2.2 Imaging software. Measurements for degrees of shortening and fracture displacement of the fracture clavicle were taken. Using a segmentation and manipulation module (ITK toolkit), five digitally reconstructed radiographs (DRRs) mimicking antero-posterior x-rays were created for every CT, with each differing by projection angle (ranging from 20° upwards tilt to 20° downwards tilt). Measurements were taken on each DRR using landmarks of entire clavicle length, distance from vertebrae to fracture (medial fragment length), distance from fracture to acromium (lateral fragment length), and horizontal shortening, and then compared to the true measurement obtained from the original CT. For all 9 samples, after comparing the measurements of clavicle fracture displacement in each 2D image, we found that an AP view with a 20° downward tilt yielded displacement measurements closest to the 3D (“gold standard”) measurements. The results agree with previous data collected from cadaveric specimens using physical X-ray film images. DDRs enable creation of multiple standard AP radiographs from which accurate tilt can be measured. The large deviation in measurements on different DRR projections motivates consideration of standardising X-ray projections. A uniform procedure would allow one to correctly evaluate the displacement of clavicular fractures if fracture displacement information is to be utilized in motivating surgical decision-making

We report two new radiographic projections for evaluating avulsion fractures at the lateral malleolus. We used seven freshly amputated legs with simulated avulsion fractures and radiopaque markers to assess their value. The projections allow accurate assessment of the displacement of fragments without superimposition, and also show whether they affect the anterior talofibular or the calcaneofibular ligament or both

Summary Statement. The current study introduced the effects of projection errors on ankle morphological measurements using CT-based simulated radiographs by correlation analysis between 2D/3D dimensions and reliability analysis with randomised perturbations while measuring planar parameters on radiographs. Introduction. Clinical success of total ankle arthroplasty (TAA) depends heavily on the available anatomy-based information of the morphology for using implants of precisely matched sizes. Among the clinically available medical imaging modalities, bi-planar projective radiographs are commonly used for this purpose owing to their convenience, low cost, and low radiation dose compared with other modalities such as MRI or CT. However, the intrinsic articular surface of the ankle joint is not symmetrical and oblique which implies that it is difficult to describe all the anatomical dimensions in detail with only one radiograph, thereby hindering the determination of accurate ankle morphometric parameters. The purposes of this study were to compare the measurements of ankle morphology using 3D CT images with those on planar 2D images; and to quantify the repeatability of the 2D measurements under simulated random perturbations. Patients & Methods. Fifty-eight fresh frozen cadaveric ankle specimens were used in the current study. Each specimen was fixed in the neutral position with a plastic frame. After fixation, the specimen-fixation construct was scanned using a 16-slice spiral CT scanner (GE BrightSpeed 16, C&G Technologies, USA) with a slice thickness of 0.625 mm. A global coordinate system was embedded in the ankle specimen with the origin at the geometric center of the talus, the anteroposterior (A/P) axis in parallel to the base-plate, the superoinferior (S/I) axis perpendicular to the base-plate, and the mediolateral (M/L) axis as the line perpendicular to both the A/P and S/I axes. Fourteen 3D morphological parameters were automatically determined using a house-developed program in MATLAB R2010a (The MathWorks, Inc., USA). A simulated standard digital radiography system, in which the X-ray focus was 1 meter away from the image plane, was also introduced to determine the planar 2D morphological parameters for comparing with those determined in 3D. Reliability with randomised perturbations during measurements was also assessed in terms of the intra-class correlation coefficients using a 2-way mixed-effects average model (ICC3, k) for intra-examiner assessments. All statistical analysis was performed using SPSS 13.0 (SPSS Inc., USA). Results. Most of the morphological parameters had high correlation and reliability, except for the maximal tibial thickness (MTiTh), distance between most vertex of tibial mortise to the level of MTiTh (MDV) and radius of trochlea tali (TaR) had moderate to low correlation which were 0.54, 0.37 and 0.09 respectively. The ICC coefficients indicated that the MDV, talus width (TaW) and inclination angle between two most vertex points of trochlea tali (MLATa) had moderate and poor reliability which were 0.59, 0.49 and 0.07 respectively. Discussion/Conclusion. The current study introduced the effects of projection errors on ankle morphological measurements using CT-based simulated radiographs by correlation analysis between 2D/3D dimensions and reliability analysis with randomised perturbations while measuring planar parameters on radiographs. MTiTh and MDV are the important parameters to help surgeon pre-surgical decision-making. TaW is one of the critical parameters for choosing accurate sise of TAA implant. It implies that the respectively accurate pose of ankle is critical during bi-planar radiography

We hypothesised that the anterior and posterior walls of the body of the first sacral vertebra could be visualised with two different angles of inlet view, owing to the conical shape of the sacrum. Six dry male cadavers with complete pelvic rings and eight dry sacrums with K-wires were used to study the effect of canting (angling the C-arm) the fluoroscope towards the head in 5° increments from 10° to 55°. Fluoroscopic images were taken in each position. Anterior and posterior angles of inclination were measured between the upper sacrum and the vertical line on the lateral view. Three authors separately selected the clearest image for overlapping anterior cortices and the upper sacral canal in the cadaveric models. The dry bone and K-wire models were scored by the authors, being sure to check whether the K-wire was in or out.

In the dry bone models the mean score of the relevant inlet position of the anterior or posterior inclination was 8.875 (standard deviation (sd) 0.35), compared with the inlet position of the opposite inclination of –5.75 (sd 4.59). We found that two different inlet views should be used separately to evaluate the borders of the body of the sacrum using anterior and posterior inclination angles of the sacrum, during placement of iliosacral screws.

Cite this article: Bone Joint J 2015;97-B:705–10.

Aims. The aim of this study is to evaluate whether acetabular retroversion (AR) represents a structural anatomical abnormality of the pelvis or is a functional phenomenon of pelvic positioning in the sagittal plane, and to what extent the changes that result from patient-specific functional position affect the extent of AR. Methods. A comparative radiological study of 19 patients (38 hips) with AR were compared with a control group of 30 asymptomatic patients (60 hips). CT scans were corrected for rotation in the axial and coronal planes, and the sagittal plane was then aligned to the anterior pelvic plane. External rotation of the hemipelvis was assessed using the superior iliac wing and inferior iliac wing angles as well as quadrilateral plate angles, and correlated with cranial and central acetabular version. Sagittal anatomical parameters were also measured and correlated to version measurements. In 12 AR patients (24 hips), the axial measurements were repeated after matching sagittal pelvic rotation with standing and supine anteroposterior radiographs. Results. Acetabular version was significantly lower and measurements of external rotation of the hemipelvis were significantly increased in the AR group compared to the control group. The AR group also had increased evidence of anterior projection of the iliac wing in the sagittal plane. The acetabular orientation angles were more retroverted in the supine compared to standing position, and the change in acetabular version correlated with the change in sagittal pelvic tilt. An anterior pelvic tilt of 1° correlated with 1.02° of increased cranial retroversion and 0.76° of increased central retroversion. Conclusion. This study has demonstrated that patients with symptomatic AR have both an externally rotated hemipelvis and increased anterior projection of the iliac wing compared to a control group of asymptomatic patients. Functional sagittal pelvic positioning was also found to affect AR in symptomatic patients: the acetabulum was more retroverted in the supine position compared to standing position. Changes in acetabular version correlate with the change in sagittal pelvic tilt. These findings should be taken into account by surgeons when planning acetabular correction for AR with periacetabular osteotomy. Cite this article: Bone Joint J 2024;106-B(2):128–135

Hip fracture represents a significant challenge, placing increasing pressure on health and social care services in Scotland. This study establishes the ‘historic’ hip fracture burden, namely, the annual number of hip fractures in Scotland, and respective incidence, between 2017 – 2021. Furthermore, the ‘projected’ hip fracture burden and incidence from 2022 – 2029 was estimated, to inform future capacity and funding of health and social care services. The number of individuals with a hip fracture in Scotland between 2017 and 2021 was identified through the Scottish Hip Fracture Audit, enabling the annual number of hip fractures and respective incidence between 2017 – 2021 to be calculated. Projection modelling was performed using Exponential Smoothing and Auto Regressive Integrated Moving Average to estimate the number of hip fractures occurring annually from 2022 – 2029. A combined average projection was employed to provide a more accurate forecast. Accounting for predicted changes within the population demographics of Scotland, the projected hip fracture incidence up to 2029 was calculated. Between 2017 and 2021 the annual number of hip fractures in Scotland increased from 6675 to 7797 (15%), with an increase in incidence from 313 to 350 per 100,000 (11%) of the at-risk population. Hip fracture was observed to increase across all groups, notably males, and the 70–79 and 80–89 age cohorts. By 2029, the combined average projection estimated the annual number of hip fractures at 10311, with an incidence rate of 463 per 100,000, representing a 32% increase from 2021. The largest percentage increase in hip fracture by 2029 occurs in the 70–79 and 80–89 age cohorts (57% and 53% respectively). Based upon these projections, overall length of hospital stay following hip fracture will increase by 60699 days per annum by 2029, incurring an additional cost of at least £25 million. Projection modelling demonstrates the annual number of hip fractures in Scotland will increase substantially by 2029, with significant implications for health and social care services. This increase in hip fracture burden and incidence is influenced strongly by changing population demographics, primarily an ageing population

Abstract. OBJECTIVE. Changes in subchondral bone are one of few disease characteristics to correlate with pain in OA. 1. Profound neuroplasticity and nociceptor sprouting is displayed within osteoarthritic (OA) subchondral bone and is associated with pain and pathology. 2. The cause of these neural changes remains unestablished. Correct innervation patterns are indispensable for bone growth, homeostasis, and repair. Axon guidance signalling factor, Sema3A is essential for the correct innervation patterning of bony tissues. 3. , expressed in osteocytes. 4. and known to be downregulated in bone OA mechanical loading. 5. Bioinformatic analysis has also shown Sema3a as a differentially expressed pathway by bone in human OA patients. 6. HYPOTHESIS: Pathological mechanical load and inflammation of bone causes dysregulation of Sema3A signalling leading to perturbed sensory nerve plasticity and pain. METHODS. Human KOLF2-C1 iPSC derived nociceptors were generated by TALEN-mediated insertion of transcription factors NGN2+Brn3A and modified chambers differentiation protocol to produce nociceptor-like cells. Nociceptor phenotype was confirmed by immunocytochemistry. Human Y201-MSC cells were embedded in 3D type-I collagen gels (0.05 × 106 cell/gel), in 48-well plates and silicone plates, were differentiated to osteocytes for 7 days before stimulation with IL-6 (5ng/ml) and soluble IL-6 receptor (sIL-6r (40ng/ml), IL6/sIL6r and mechanical load mimetic Yoda1 (5μM) or unstimulated (n=5/group) (48-well plates) or were mechanically loaded in silicone plates (5000μstrain, 10Hz, 3000 cycles) or not loaded (n=5/group). Conditioned media transfer was performed from osteocyte to nociceptor cultures assessed by continuous 24-hour phase contrast confocal microscopy. 24-hours after stimulation RNA was quantified by RT-qPCR (IL6) or RNAseq whole transcriptome analysis/DEseq2 analysis (Load). Protein release was quantified by ELISA. Normally distributed data with homogenous variances was analysed by two-tailed t test. RESULTS. IPSC-derived nociceptor-like cells display elongated (>5mm) dendritic projections and nociceptive molecular markers such as TUJ1, PrPH and Neun and TrkA. Sema3A signalling ligands were expressed in 100% of osteocyte cultures. Mechanical loading regulated the Sema3 pathway; Sema3A (0.4-fold, p<0.001), Sema3B (13-fold, p<0.001), Sema3C (0.4-fold, p<0.001). Under inflammatory stimulation by IL6/IL6sR, SEMA3A (7-fold, p=0.01) and receptor Plexin1 (3-fold, p=0.03) show significant regulation. Sema3A protein release showed a significant downregulation of Sema3A release by IL6/sIL6r+Yoda1 (2-fold, p=0.02). Continuous 24-hour phase contrast confocal microscopy measuring the number of extending/retreating dendritic projections revealed that sensory nerve cultures exposed to media from osteocytes stimulated with IL-6/sIL-6R+Yoda1 displayed significantly more invading dendritic projections (p=0.0175, 12-fold±SEM 3.5) across 3 random fields of view within a single stimulated neural culture and significantly fewer retracting dendritic projections (p=0.0075, 2-fold±SEM 0.33) compared to controls. CONCLUSIONS. Here we show osteocytic regulation of Sema3A under pathological mechanical loading and the ability of media pathologically loaded osteocyte cultures to induce the branching and invasion of cultured nociceptor-like cells as displayed in OA subchondral bone. Declaration of Interest. (b) declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported:I declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project

The hip fracture burden on health and social care services in Scotland is anticipated to increase significantly, primarily driven by an ageing population. This study forecasts future hip fracture incidence and the annual number of hip fractures in Scotland until 2029. The monthly number of patients with hip fracture aged ≥ 50 admitted to a Scottish hospital between 01/01/2017 and 31/12/2021 was identified through data collected by the Scottish Hip Fracture Audit. This data was analysed using Exponential Smoothing and Auto Regressive Integrated Moving Average forecast modelling to project future hip fracture incidence and the annual number of hip fractures until 2029. Adjustments for population change were accounted for by integrating population projections published by National Records of Scotland. Between 2017 and 2021 the annual number of hip fractures in Scotland increased from 6675 to 7797, with a respective increase in hip fracture incidence from 313 to 350 per 100,000. By 2029, the averaged projected annual number of hip fractures is 10311, with an incidence rate of 463 per 100,000. The largest percentage increase in hip fracture occurs in the 70-79 age group (57%), with comparable increases in both sexes (30%). Based upon these projections, overall length of stay following hip fracture will increase from 142713 bed days per annum in 2021, to 203412 by 2029, incurring an additional cost of over £25 million. Forecast modelling demonstrates that the annual number of hip fractures in Scotland will rise substantially by 2029, with considerable implications for health and social care services

Aims. Traditionally, total hip arthroplasty (THA) templating has been performed on anteroposterior (AP) pelvis radiographs. Recently, additional AP hip radiographs have been recommended for accurate measurement of the femoral offset (FO). To verify this claim, this study aimed to establish quantitative data of the measurement error of the FO in relation to leg position and X-ray source position using a newly developed geometric model and clinical data. Methods. We analyzed the FOs measured on AP hip and pelvis radiographs in a prospective consecutive series of 55 patients undergoing unilateral primary THA for hip osteoarthritis. To determine sample size, a power analysis was performed. Patients’ position and X-ray beam setting followed a standardized protocol to achieve reproducible projections. All images were calibrated with the KingMark calibration system. In addition, a geometric model was created to evaluate both the effects of leg position (rotation and abduction/adduction) and the effects of X-ray source position on FO measurement. Results. The mean FOs measured on AP hip and pelvis radiographs were 38.0 mm (SD 6.4) and 36.6 mm (SD 6.3) (p < 0.001), respectively. Radiological view had a smaller effect on FO measurement than inaccurate leg positioning. The model showed a non-linear relationship between projected FO and femoral neck orientation; at 30° external neck rotation (with reference to the detector plane), a true FO of 40 mm was underestimated by up to 20% (7.8 mm). With a neutral to mild external neck rotation (≤ 15°), the underestimation was less than 7% (2.7 mm). The effect of abduction and adduction was negligible. Conclusion. For routine THA templating, an AP pelvis radiograph remains the gold standard. Only patients with femoral neck malrotation > 15° on the AP pelvis view, e.g. due to external rotation contracture, should receive further imaging. Options include an additional AP hip view with elevation of the entire affected hip to align the femoral neck more parallel to the detector, or a CT scan in more severe cases. Cite this article: Bone Jt Open 2022;3(10):795–803

The rising prevalence of osteoarthritis, associated with an ageing population, is expected to deliver increasing demand across Scotland for arthroplasty services in the future. Understanding the scale of potential change to operative workflow is essential to ensure adequate provision of services and prevent prolonged waiting times that can cause patient harm. This future service demand for primary and revision hip arthroplasty across Scotland, and the rest of the U.K., is hitherto unknown. We set out to provide projections of future primary & revision hip arthroplasty out to 2038 utilising historical trend data (2008–2018) from the Scottish Arthroplasty Project. All analyses were performed using the Holt's exponential smoothing projection method with the forecast package in R statistics. Results were adjusted for projected future population estimates provided by National Records of Scotland. Independent age & sex group predictions were also performed. All results are presented per 100,000 population at-risk per year (/100k/year). The predicted rise of primary hip arthroplasty for all ages is from 120/100k/year in 2018 to 152/100k/year in 2038, a 27% increase. Based on a static 3 day length of stay average this would see 4280 additional patient bed days required for primary hip arthroplasty patients per annum. The number of revision hip arthroplasty procedures for all ages is projected to fall from 14/100k/year to 4/100k/year based on historical trend data. This does not however take into account the suspect increase in primary arthroplasty numbers that is likely to influence future revision rates. Anticipated future demand for primary hip arthroplasty will require significant additional resource and funding to prevent deterioration in quality of care and an increase in patient wait times. Demand for revision arthroplasty is set to decrease, likely on account of improved implant materials, technique, and understanding of best practice to minimise complication risk. This doesn't however take into account the impact of the complex interaction between an increasing primary arthroplasty rate and revision risk. Understanding presented projections of changes to arthroplasty demand is key to future service delivery

Aims. In computer simulations, the shape of the range of motion (ROM) of a stem with a cylindrical neck design will be a perfect cone. However, many modern stems have rectangular/oval-shaped necks. We hypothesized that the rectangular/oval stem neck will affect the shape of the ROM and the prosthetic impingement. Methods. Total hip arthroplasty (THA) motion while standing and sitting was simulated using a MATLAB model (one stem with a cylindrical neck and one stem with a rectangular neck). The primary predictor was the geometry of the neck (cylindrical vs rectangular) and the main outcome was the shape of ROM based on the prosthetic impingement between the neck and the liner. The secondary outcome was the difference in the ROM provided by each neck geometry and the effect of the pelvic tilt on this ROM. Multiple regression was used to analyze the data. Results. The stem with a rectangular neck has increased internal and external rotation with a quatrefoil cross-section compared to a cone in a cylindrical neck. Modification of the cup orientation and pelvic tilt affected the direction of projection of the cone or quatrefoil shape. The mean increase in internal rotation with a rectangular neck was 3.4° (0° to 7.9°; p < 0.001); for external rotation, it was 2.8° (0.5° to 7.8°; p < 0.001). Conclusion. Our study shows the importance of attention to femoral implant design for the assessment of prosthetic impingement. Any universal mathematical model or computer simulation that ignores each stem’s unique neck geometry will provide inaccurate predictions of prosthetic impingement. Cite this article: Bone Joint Res 2021;10(12):780–789

Evaluate precisely and reproducibly tridimensional positioning of bone tunnels in anterior cruciate ligament reconstructions (ACL). To propose biplanar stereoradiographic imaging as a new reference in tridimensional evaluation of ACL reconstruction (ACLR). Comparing knee 3D models issued from EOStm low-irradiation biplanar X-Ray with those issued from computed tomography (CT-Scan) high definition images will allow a bone morphological description of a previously unseen precision. We carried out the transfer of 3D models from EOStm X-Ray images obtained from 10 patients in the same reference frame with models issued from CT-Scan. Two evaluators reconstructed both pre-operative and post-operative knees, using two different stereoradiographic projections, for a total of 144 knee 3D models from EOStm. A surface analysis by distance mapping allowed us to know the differences or errors between the homologous points of the EOStm and CT reconstructions, the latter being our “bronze-standard”. At the femur, we obtained a mean (95% confidence level) error of 1.5 mm (1.3–1.6) between the EOStm models compared to the Arthro-CT segmentations when using AP-LAT incidences, compared to 1 mm (1.0 – 1.1) with oblique projections. For the tunnels placement analysis, the total radius difference between EOStm and Arthro-CT's femoral tunnel apertures was 0.8 mm (0.4–1.2) in AP-LAT and 0.6 mm (0.0–1.2) in oblique views. These femoral apertures positioning on EOStm models were within 4.3 mm (3.0–5.7) of their homologues on CT-Scan models, 4.6 mm (3.5–5.6) with the oblique views. Furthermore, 9.3o (7.2–11.4) of difference in direction between femoral tunnels from EOStm models and CT reconstructions is obtained with AP-LAT projections, 8.3o (6.6–10) with obliques views. Measures of these parameters were also performed at the tibia. According to the intra and inter-reproducibility analysis of our knee 3D models, EOStm biplanar X-Ray images prove to be fast, efficient and precise in the design of ACLR 3D models with respect to CT-Scan. Our results also propose the recourse of oblique stereoradiographic projections for the realization of knee 3D models. These models will be subjects of further analysis and will allow us eventually to propose a new frame of reference guiding the positioning of the tunnels in the ACLR

Osteotomies in the musculoskeletal system are joint preserving procedures to correct the alignment of the patient. In the lower limb, most of the pre-operative planning is performed on full leg weightbearing radiographs. However, these images contain a 2-dimensional projection of a 3-dimensional deformity, lack a clear visualization of the joint surface and are prone to rotational errors during patient positioning. Weightbearing CT imaging has demonstrated to overcome these shortcomings during the first applications of this device at level of the foot and ankle. Recent advances allow to scan the entire lower limb and novel applications at the level of the knee and hip are on the rise. Here, we will demonstrated the current techniques and 3-dimensional measurements used in supra- and inframalleolar osteotomies around the ankle. Several of these techniques will be transposed to other parts in the lower limb to spark future studies in this field

The rising prevalence of osteoarthritis, associated with an ageing population, is expected to deliver increasing demand across Scotland for primary hip and knee arthroplasty in the future. Understanding the scale of potential change to operative workflow is essential to ensure adequate provision of services, and prevent prolonged waiting times that can cause patient harm. We therefore set out to provide projections of future primary hip and knee arthroplasty out to 2038 utilising historical trend data (2008–2018) from the Scottish Arthroplasty Project. All analyses were performed using the Holt's exponential smoothing projection method with the forecast package in R statistics. Results were adjusted for projected future population estimates provided by National Records of Scotland. Independent age & sex group predictions were also performed. All results are presented per 100,000 population at-risk per year (/100k/year). The predicted rise of primary hip arthroplasty for all ages is from 120/100k/year in 2018 to 152/100k/year in 2038, a 27% increase. The predicted rise of primary knee arthroplasty for all ages is from 164/100k/year in 2018 to 220/100k/year in 2038, a 34% increase. Based on a static 3 day length of stay average this would see 4280 additional patient bed days for hips, and 7392 for knees, required nationally per year by 2038. The associated supplementary cost to the NHS is anticipated to be around £21 million per annum. Knowledge of increasing resource utilisation and cost associated with predicted future demand for primary hip and knee arthroplasty provides key information for service organisation and delivery

Aims. The current study aimed to compare robotic arm-assisted (RA-THA), computer-assisted (CA-THA), and manual (M-THA) total hip arthroplasty regarding in-hospital metrics including length of stay (LOS), discharge disposition, in-hospital complications, and cost of RA-THA versus M-THA and CA-THA versus M-THA, as well as trends in use and uptake over a ten-year period, and future projections of uptake and use of RA-THA and CA-THA. Methods. The National Inpatient Sample was queried for primary THAs (2008 to 2017) which were categorized into RA-THA, CA-THA, and M-THA. Past and projected use, demographic characteristics distribution, income, type of insurance, location, and healthcare setting were compared among the three cohorts. In-hospital complications, LOS, discharge disposition, and in-hospital costs were compared between propensity score-matched cohorts of M-THA versus RA-THA and M-THA versus CA-THA to adjust for baseline characteristics and comorbidities. Results. RA-THA and CA-THA did not exhibit any clinically meaningful reduction in mean LOS (RA-THA 2.2 days (SD 1.4) vs 2.3 days (SD 1.8); p < 0.001, and CA-THA 2.5 days (SD 1.9) vs 2.7 days (SD 2.3); p < 0.001, respectively) compared to their respective propensity score-matched M-THA cohorts. RA-THA, but not CA-THA, had similar non-home discharge rates to M-THA (RA-THA 17.4% vs 18.5%; p = 0.205, and 18.7% vs 24.9%; p < 0.001, respectively). Implant-related mechanical complications were lower in RA-THA (RA-THA 0.5% vs M-THA 3.1%; p < 0.001, and CA-THA 1.2% vs M-THA 2.2%; p < 0.001), which was associated with a significantly lower in-hospital dislocation (RA-THA 0.1% vs M-THA 0.8%; p < 0.001). Both RA-THA and CA-THA demonstrated higher mean higher index in-hospital costs (RA-THA $18,416 (SD $8,048) vs M-THA $17,266 (SD $8,396); p < 0.001, and CA-THA $20,295 (SD $8,975) vs M-THA $18,624 (SD $9,226); p < 0.001, respectively). Projections indicate that 23.9% and 3.2% of all THAs conducted in 2025 will be robotic arm- and computer-assisted, respectively. Projections indicated that RA-THA use may overtake M-THA by 2028 (48.3%) and reach 65.8% of all THAs by 2030. Conclusion. Technology-assisted THA, particularly RA-THA, may provide value by lowering in-hospital early dislocation rates and and other in-hospital metrics compared to M-THA. Higher index-procedure and hospital costs warrant further comprehensive cost analyses to determine the true added value of RA-THA in the episode of care, particularly since we project that one in four THAs in 2025 and two in three THA by 2030 will use RA-THA technology. Cite this article: Bone Joint J 2021;103-B(9):1488–1496

Unicompartmental knee arthroplasty (UKA) is associated with a higher risk of revision compared with total knee arthroplasty (TKA). The outcomes of knee arthroplasty are typically presented as implant survival or incidence of revision after a set number of years, which can be difficult for patients and clinicians to conceptualise. We aimed to calculate the ‘lifetime risk’ of revision for UKA as a more relatable estimate of risk projection over a patient's remaining lifetime, and make comparisons to TKA. All primary UKAS performed from 1999 to 2019 (n=13,481) captured by the New Zealand Joint Registry (NZJR) were included. The lifetime risk of revision was calculated and stratified by age, gender and American Society of Anesthesiologists (ASA) status. The lifetime risk of revision for UKA was highest in the youngest patients (46-50 years; 40.4%) and lowest in the oldest patients (86-90 years; 3.7%). Lifetime risk of revision was higher for females (range 4.3%-43.4% cf. males 2.9%-37.4%) and patients with higher ASA status (ASA 3-4 range 8.8%-41.2% cf. ASA 1 1.8%-29.8%), regardless of age. The lifetime risk of UKA was two-fold higher than TKA (ranging from 3.7%-40.4% UKA, 1.6%-22.4% TKA) across all age groups. Increased risk of revision in the younger patients was associated with aseptic loosening in both males and females, and pain in females. Periprosthetic joint infections (PJI) accounted for 4% of all UKA revisions, in contrast to 27% for TKA; risk of PJI was higher for males than females for both procedures. The lifetime risk of revision is a more meaningful measure of arthroplasty outcomes and can aid with patient counselling prior to UKA. Findings from this study show the increased lifetime risk of UKA revision for younger patients, females and those with higher ASA status

Though dentin matrix protein 1 (Dmp1) is known to play critical role in mediating bone mineralization, it has also been validated to be expressed in brain and helps maintain blood brain barrier (BBB). Our study aims to clarify the expression pattern of Dmp1 in mouse brain and explore whether intercellular mitochondrial transfer occurs between Dmp1 positive astrocytes (DPAs) and endothelial cells, and thus acting as a mechanism in maintaining BBB during aging. Single cell RNA sequencing (scRNAseq) of 1 month, 6 month, and 20 month old mice brain (n=1, respectively) was employed to identify Dmp1 positive cell types. Dmp1. Cre. -mGmT and Dmp1. Cre. -COX8a fluorescent mice were generated to visualize DPAs and investigate their mitochondrial activities. A 3D noncontact coculture system and mitochondrial transplantation were applied to study the role of mitochondrial transfer between astrocytes and bEnd.3 endothelial cells. Dmp1. Cre. -Mfn2. f/f. mice were generated by depleting the ER-mitochondria tethering protein Mfn2 in DPAs. Dmp1 was mainly expressed in astrocytes at different ages. GO analysis revealed that cell projection and adhesion of DPAs were upregulated. Confocal imaging on Dmp1. Cre. -mGmT mice indicated that DPAs are a cluster of astrocytes that closely adhere to blood vessels (n=3). Bioinformatics analysis revealed that mitochondrial activity of DPAs were compromised during aging. Enriched scRNAseq of fluorescent cells from Dmp1. Cre. -COX8a mice (n=2) and immunofluorescent imaging (n=3) validated the acquisition of extrinsic mitochondria in endothelial cells. 3D coculture of astrocytes and bEnd.3 and direct mitochondrial transplantation revealed the rescue effect of mitochondrial transfer on damaged bEnd.3. BBB was impaired after depleting Mfn2 in DPAs, expressing a similar phenotype with aging brain. Astrocytes that express Dmp1 play a significant role in maintaining BBB via transferring mitochondria to vascular endothelial cells. Compromised mitochondrial transfer between DPAs and endothelial cells might be the potential mechanism of impaired BBB during aging

The aim was to determine reliability in treatment threshold based on USS angular measurements between observers involved in the DDH hip screening programme at the NOC and assess the effect of image orientation on the accuracy of these measurements. 3 independent observers measured alpha and beta angles on bilateral hips in 10 consecutive patients seen in the DDH hip screening clinic. All scans were performed by a single radiographer and observers used the same set of USS images for a given patient. Each observer measured alpha and beta angles a total of 4 times: conventional ultrasound image projection (with the ilium horizontal) (round 1), Graf's anatomical projection (round 2), and both techniques repeated 1 month later (round 3 and 4 respectively) to assess intra-observer reliability. To determine its effect on treatment threshold taking into account alpha and beta angles and patient's age, the consistency between observers' management recommendations was evaluated for each round. Possible outcomes were: 1) patient discharged, 2) no treatment needed yet, but follow-up required, 3) start treatment. Intra-observer reliability for conventional projection was moderate (Kappa 0.58), and improved for anatomical projection (Kappa 0.65). Inter-observer reliability, as a surrogate measure of consistency in management recommendations between observers, ranged from fair to moderate across the 4 rounds (Kappa 0.30 – 0.50). However, contrary to previous recommendations, reliability was better with conventional projection (Kappa 0.41 (95% CI 0.11–0.72)) compared to anatomical projection (Kappa 0.36 (95% CI −0.01–0.73)). The overall agreement in management recommendations, pooling all results across 4 rounds, was 51.3% (Kappa 0.39 (95%CI 0.15–0.63)). This audit supports the argument that anatomical image projection improves intra-observer consistency. However, as with all USS measurements, angular measurements were highly user dependent and treatment threshold based on USS may not be as consistent as anticipated

The purpose of this study is to report the clinical and radiological outcomes of patients undergoing primary or revision reverse total shoulder arthroplasty using custom 3D printed components to manage severe glenoid bone loss with a minimum of 2-year follow-up. After ethical approval (reference: 17/YH/0318), patients were identified and invited to participate in this observational study. Inclusion criteria included: 1) severe glenoid bone loss necessitating the need for custom implants; 2) patients with definitive glenoid and humeral components implanted more than 2 years prior; 3) ability to comply with patient reported outcome questionnaires. After seeking consent, included patients underwent clinical assessment utilising the Oxford Shoulder Score (OSS), Constant-Murley score, American Shoulder and Elbow Society Score (ASES), and quick Disabilities of the Arm, Shoulder, and Hand Score (quickDASH). Radiographic assessment included AP and axial projections. Patients were invited to attend a CT scan to confirm osseointegration. Statistical analysis utilised included descriptive statistics (mean and standard deviation) and paired t test for parametric data. 3 patients had revision surgery prior to the 2-year follow-up. Of these, 2/3 retained their custom glenoid components. 4 patients declined to participate. 5 patients were deceased at the time of commencement of the study. 21 patients were included in this analysis. The mean follow-up was 36.1 months from surgery (range 22–60.2 months). OSS improved from a mean 16 (SD 9.1) to 36 (SD 11.5) (p < 0.001). Constant-Murley score improved from mean 9 (SD 9.2) to 50 (SD 16.4) (p < 0.001). QuickDASH improved from mean 67 (SD 24) to 26 (SD 27.2) (p = 0.004). ASES improved from mean 28 (SD 24.8) to 70 (SD 23.9) (p = 0.007). Radiographic evaluation demonstrated good osseointegration in all 21 included patients. The utility of custom 3D-printed components for managing severe glenoid bone loss in primary and revision reverse total shoulder arthroplasty yields significant clinical improvements in this complex patient cohort

Aims. Unicompartmental knee arthroplasty (UKA) has a higher risk of revision than total knee arthroplasty (TKA), particularly for younger patients. The outcome of knee arthroplasty is typically defined as implant survival or revision incidence after a defined number of years. This can be difficult for patients to conceptualize. We aimed to calculate the ‘lifetime risk’ of revision for UKA as a more meaningful estimate of risk projection over a patient’s remaining lifetime, and to compare this to TKA. Methods. Incidence of revision and mortality for all primary UKAs performed from 1999 to 2019 (n = 13,481) was obtained from the New Zealand Joint Registry (NZJR). Lifetime risk of revision was calculated for patients and stratified by age, sex, and American Society of Anesthesiologists (ASA) grade. Results. The lifetime risk of revision was highest in the youngest age group (46 to 50 years; 40.4%) and decreased sequentially to the oldest (86 to 90 years; 3.7%). Across all age groups, lifetime risk of revision was higher for females (ranging from 4.3% to 43.4% vs males 2.9% to 37.4%) and patients with a higher ASA grade (ASA 3 to 4, ranging from 8.8% to 41.2% vs ASA 1 1.8% to 29.8%). The lifetime risk of revision for UKA was double that of TKA across all age groups (ranging from 3.7% to 40.4% for UKA, and 1.6% to 22.4% for TKA). The higher risk of revision in younger patients was associated with aseptic loosening in both sexes and pain in females. Periprosthetic joint infection (PJI) accounted for 4% of all UKA revisions, in contrast with 27% for TKA; the risk of PJI was higher for males than females for both procedures. Conclusion. Lifetime risk of revision may be a more meaningful measure of arthroplasty outcomes than implant survival at defined time periods. This study highlights the higher lifetime risk of UKA revision for younger patients, females, and those with a higher ASA grade, which can aid with patient counselling prior to UKA. Cite this article: Bone Joint J 2022;104-B(6):672–679

Due to changes in population demographics, the burden of hip fractures in Scotland is expected to rise dramatically over the coming decades. This study aims to establish the future incidence of hip fracture in Scotland in individuals aged 50 and over. The number of patients admitted to hospital in Scotland with a hip fracture between 1999 and 2016 were ascertained from discharge coding across NHS Scotland. The annual number of hip fractures were categorised to enable gender and age specific hip fracture incidence rates to be calculated. Through static and variable projection methods, the annual hip fracture incidence up to 2035 was forecast and analysed with respect to specific demographics ascertained from population data provided by the National Records of Scotland. Between 1999 and 2016 the total number of hip fractures in individuals aged 50 and over increased by 11%, from 7,131 to 7,930, equating to an average year-on-year increase of 0.6%. Patients aged over 75 consistently accounted for more than 85% of recorded hip fractures, with females having a higher incidence rate than males across all age groups. A decreasing incidence in females aged over 70 was observed. Using multiple projection methods, the annual number of hip fractures in Scotland is predicted to increase by 55% from 7,930 in 2016, to an average of 12,316 by 2035. Projection modelling confirms the annual number of hip fractures in Scotland will rise substantially by 2035 with considerable implications for health and social care provision

Aims. Waiting times for arthroplasty surgery in Northern Ireland are among the longest in the NHS, which have been further lengthened by the onset of the COVID-19 global pandemic in March 2020. The Department of Health in Northern Ireland has announced a new Elective Care Framework (ECF), with the framework proposing that by March 2026 no patient will wait more than 52 weeks for inpatient/day case treatment. We aimed to assess the feasibility of achieving this with reference to total hip arthroplasty (THA) and total knee arthroplasty (TKA). Methods. Mathematical modelling was undertaken to calculate when the ECF targets will be achieved for THA and TKA, as well as the time when waiting lists for THA and TKA will be cleared. The number of patients currently on the waiting list and percentage operating capacity relative to pre-COVID-19 capacity was used to determine future projections. Results. As of May 2021, there were 3,757 patients awaiting primary THA and 4,469 patients awaiting primary TKA in Northern Ireland. Prior to April 2020, there were a mean 2,346 (2,085 to 2,610) patients per annum boarded for primary THA, a mean 2,514 (2,494 to 2,514) patients per annum boarded for primary TKA, and there were a mean 1,554 primary THAs and 1,518 primary TKAs performed per annum. The ECF targets for THA will only be achieved in 2030 if operating capacity is 200% of pre COVID-19 pandemic capacity and in 2042 if capacity is 170%. For TKA, the targets will be met in 2034 if capacity is 200% of pre-COVID-19 pandemic capacity. Conclusion. This modelling demonstrates that, in the absence of major funding and reorganization of elective orthopaedic care, the targets set out in the ECF will not be achieved with regard to THA and TKA. Waiting times for THA and TKA surgery in Northern Ireland are likely to remain greater than 52 weeks for most of this decade. Cite this article: Bone Jt Open 2022;3(4):302–306

Waiting times for arthroplasty surgery in Northern Ireland are among the longest in the National Health Service, which have been further lengthened by the onset of the SARS-CoV-19 global pandemic in March 2020. The Department of Health (DoH) in Northern Ireland has announced a new Elective Care Framework (ECF), with the framework proposing that by March 2026 no patient will wait more than 52 weeks for inpatient/day case treatment. We aimed to assess the feasibility of achieving this with reference to Total Hip Arthroplasty (THA). Waiting list information was obtained via a Freedom of Information request to the DoH (May 2021) and National Joint Registry data was used to determine baseline operative numbers. Mathematical modelling was undertaken to calculate the time taken to meet the ECF target and also to determine the time to clear the waiting lists for THA using the number of patients currently on the waiting list and percentage operating capacity relative to pre-Covid-19 capacity to determine future projections. As of May 2021, there were 3,757 patients awaiting primary THA in Northern Ireland. Prior to April 2020, there were a mean 2,346 patients/annum added to the waiting list for primary THA and there were a mean 1,624 primary THAs performed per annum. The ECF targets for THA will only be achieved in 2026 if operating capacity is 200% of pre COVID-19 pandemic capacity and will be achieved in 2030 if capacity is 170%. Surgical capacity must exceed pre-Covid capacity by at least 30% to meet ongoing demand. THA capacity was significantly reduced following resumption of elective orthopaedics post-COVID-19 (22% of pre-COVID-19 capacity – 355 THAs/annum post-COVID-19 versus 1,624/annum pre-COVID-19). This modelling demonstrates that, in the absence of major funding and reorganisation of elective orthopaedic care, the targets set out in the ECF will not be achieved with regards to hip arthroplasty. Waiting times for THA surgery in the NHS in Northern Ireland are likely to remain greater than 52 weeks for most of this decade

We investigated 60 patients (89 feet) with a mean age of 64 years (61 to 67) treated for congenital clubfoot deformity, using standardised weight-bearing radiographs of both feet and ankles together with a functional evaluation. Talocalcaneal and talonavicular relationships were measured and the degree of osteo-arthritic change in the ankle and talonavicular joints was assessed. The functional results were evaluated using a modified Laaveg-Ponseti score. The talocalcaneal (TC) angles in the clubfeet were significantly lower in both anteroposterior (AP) and lateral projections than in the unaffected feet (p < 0.001 for both views). There was significant medial subluxation of the navicular in the clubfeet compared with the unaffected feet (p < 0.001). Severe osteoarthritis in the ankle joint was seen in seven feet (8%) and in the talonavicular joint in 11 feet (12%). The functional result was excellent or good (≥ 80 points) in 29 patients (48%), and fair or poor (< 80 points) in 31 patients (52%). Patients who had undergone few (0 to 1) surgical procedures had better functional outcomes than those who had undergone two or more procedures (p < 0.001). There was a significant correlation between the functional result and the degree of medial subluxation of the navicular (p < 0.001, r. 2 . = 0.164), the talocalcaneal angle on AP projection (p < 0.02, r2 = 0.025) and extent of osteoarthritis in the ankle joint (p < 0.001). We conclude that poor functional outcome in patients with congenital clubfoot occurs more frequently in those with medial displacement of the navicular, osteoarthritis of the talonavicular and ankle joints, and a low talocalcaneal angle on the AP projection, and in patients who have undergone two or more surgical procedures. However, the ankle joint in these patients appeared relatively resistant to the development of osteoarthritis

Introduction and Objective. Up to 30% of thoracolumbar (TL) fractures are missed in the emergency room. Failure to identify these fractures can result in neurological injuries up to 51% of the casesthis article aimed to clarify the incidence and risk factors of traumatic fractures in China. The China National Fracture Study (CNFS. Obtaining sagittal and anteroposterior radiographs of the TL spine are the first diagnostic step when suspecting a traumatic injury. In most cases, CT and/or MRI are needed to confirm the diagnosis. These are time and resource consuming. Thus, reliably detecting vertebral fractures in simple radiographic projections would have a significant impact. We aim to develop and validate a deep learning tool capable of detecting TL fractures on lateral radiographs of the spine. The clinical implementation of this tool is anticipated to reduce the rate of missed vertebral fractures in emergency rooms. Materials and Methods. We collected sagittal radiographs, CT and MRI scans of the TL spine of 362 patients exhibiting traumatic vertebral fractures. Cases were excluded when CT and/or MRI where not available. The reference standard was set by an expert group of three spine surgeons who conjointly annotated (fracture/no-fracture and AO Classification) the sagittal radiographs of 171 cases. CT and/or MRI were used confirm the presence and type of the fracture in all cases. 302 cropped vertebral images were labelled “fracture” and 328 “no fracture”. After augmentation, this dataset was then used to train, validate, and test deep learning classifiers based on the ResNet18 and VGG16 architectures. To ensure that the model's prediction was based on the correct identification of the fracture zone, an Activation Map analysis was conducted. Results. Vertebras T12 to L2 were the most frequently involved, accounting for 48% of the fractures. Accuracies of 88% and 84% were obtained with ResNet18 and VGG16 respectively. The sensitivity was 89% with both architectures but ResNet18 had a significantly higher specificity (88%) compared to VGG16 (79%). The fracture zone used was precisely identified in 81% of the heatmaps. Conclusions. Our AI model can accurately identify anomalies suggestive of TL vertebral fractures in sagittal radiographs precisely identifying the fracture zone within the vertebral body

Liner exchange and bone grafting are commonly used in cases of wear and osteolysis around well- fixed acetabular components in revision total hip arthroplasty. However, in total knee revision, liner exchange is a more rare option. In a multicenter study, we evaluated 22 TKAs that were revised with liner exchange and bone grafting for wear and osteolysis. All knees were well-fixed and well-aligned, and all components were modular tibial components. Osteolytic areas averaged 21.1cm2 and 7.6cm2 on AP projections of the femur and tibia, respectively, and averaged 21.6cm2 and 5.7cm2 on lateral projections of the femur and tibia, respectively, with the largest area being 54cm2 on a single projection. Follow up was minimum 2 years and average 40 months. No knees were revised and radiographically, all osteolytic lesions showed evidence of complete or partial graft incorporation. In addition, there was no radiographic evidence of loosening at final follow up. The Mayo Clinic evaluated 56 isolated tibial insert exchange revisions at their institution. Cases of loosening, infection, knee stiffness, or extensor mechanism problems were excluded. At minimum 2-year follow up (average 4.6 years), 14 knees (25%) required re-revision. Baker et al. evaluated 45 total knees undergoing isolated tibial insert exchange. At minimum 2 years, 4 knees (9%) required revision. Significant improvement was seen in clinical outcomes questionnaires, but only 58% had clinical successful global WOMAC scores. In summary, isolated liner exchange in the revision total knee setting has variable results. It can be successful but it is indeed a rare option and should be limited to cases were the total knee arthroplasty is both well-fixed and well-aligned

Introduction and Objective. Joint malleolar fractures have been estimated around 9% of all fractures. They are characterized by different both early and late complications. Among the latter, arthrofibrosis and early secondary arthrosis represent the two most common ones. Moreover, these two complications could be considered related to each other. Their real cause is still under investigation, even if residual post-operative hematoma and acute post-traumatic synovitis appear to be the most accredited. Supporting this hypothesis, joint debridement and the evacuation of the post-operative hematoma could represent a possible solution. The aim of this prospective study is to evaluate the role of arthroscopic lavage and debridement during internal fixation in order to prevent late joint complications. Materials and Methods. Sixty consecutive patients who reported dislocated articular ankle fractures with surgical indication of open reduction and internal fixation (ORIF) have been included in this study. 27 patients underwent ORIF surgery associated with arthroscopic washout and debridement, while 33 patients, representing the control group, underwent just internal reduction and osteosynthesis. Patients with pure dislocations, non-articular fractures, polytrauma, previous local trauma, metabolic and connective pathologies were excluded. Follow-up was performed at 40 days (T1), 3 (T2) and 6 months (T3) after trauma for all patients. If necessary, some have been re-evaluated 12 months after the trauma. Efficacy of the treatment was evaluated through the VAS scale, Maryland scale, search for local complications such as dehiscence or infections, and finally radiographic evaluation. T-Student was estimated in order to individuate statistical significance. Results. VAS scale showed higher values for the case group than the control group with mean values of 2.7 and 4.2 at T1 and 2.1 and 3.8 at T2, respectively. At 6 months follow-up, the VAS values resulted similar with 2.6 for the case group and 2.8 for the control group. The same projections were found for the Maryland scale, with values of 61.5 and 40.7 at T1, 80.8 and 68.0 at T2 and 87.8 and 85.0 with no significant differences at T3 respectively. No significant differences were detected for complications or radiographic evaluation. Conclusions. Our study has shown significance differences in terms of pain and time for recovery only in the very short term follow up. Although our study, due to the specific limits, cannot be considered diriment, on the basis of the data, we could hypothesize that the aforementioned hypothesis may remain valid for the non-acute hematoma or that the cause of the arthrofibrosis should be sought somewhere else. However, evidence is low, and further research is needed

Liner exchange and bone grafting are commonly used in cases of wear and osteolysis around well fixed acetabular components in revision total hip arthroplasty. However, in total knee revision, liner exchange is a more rare option. In a multicenter study, we evaluated 22 TKAs that were revised with liner exchange and bone grafting for wear and osteolysis. All knees were well fixed and well aligned, and all components were modular tibial components. Osteolytic areas averaged 21.1 cm2 and 7.6 cm2 on AP projections of the femur and tibia, respectively, and averaged 21.6 cm2 and 5.7 cm2 on lateral projections of the femur and tibia, respectively, with the largest area being 54 cm2 on a single projection. Follow up was minimum 2 years and average 40 months. No knees were revised and radiographically, all osteolytic lesions showed evidence of complete or partial graft incorporation. In addition, there was no radiographic evidence of loosening at final follow up. The Mayo Clinic evaluated 56 isolated tibial insert exchange revisions at their institution. Cases of loosening, infection, knee stiffness, or extensor mechanism problems were excluded. At minimum 2 year follow up (average 4.6 years), 14 knees (25%) required re-revision. Baker et al evaluated 45 total knees undergoing isolated tibial insert exchange. At minimum 2 years, 4 knees (9%) required revision. Significant improvement was seen in clinical outcomes questionnaires, but only 58% had clinical successful global WOMAC scores. In summary, isolated liner exchange in the revision total knee setting has variable results. It can be successful but it is indeed a rare option and should be limited to cases where the total knee arthroplasty is both well fixed and well aligned

Abstract. Background. Accurate analysis of the patellar resurfacing is essential to better understand the etiology of patella-femoral problems and dissatisfaction following total knee arthroplasty (TKA). In the current published literature patellar resurfacing is analysed using 2D radiographs. With use of radiographs there is potential for error due to differences in limb positioning, projection, anatomic variability and difficulties in appreciating the cement-bone interface. So, we have developed a CT Scan based 3D modelled technique for accurate evaluation of patellar resurfacing. Methods. This technique for analyses of patellar resurfacing is based on the pre-operative and pos-operative CT Scan data of the patients who underwent TKA with patellar resurfacing. In the first step, accurately landmarked 3D models of pre-op patellae were created from pre-operative CT Scan data in ScanIP software. This model was imported in Geomagic design software and computational model of post-op patella was created. This was further analysed to determine the inclination of the patellar resection plane, patellar button positioning and articular volumetric restoration of the patella. Reliability and reproducibility of the technique was tested by comparing 3 sets of 10 measurements done by 2 independent investigators on 30 computational models of patellae derived from the data of randomly chosen 30 TKA patients. Results. The developed technique for analyses of patellar resurfacing is reliable and reproducible. The intraclass correlation co-efficient was >0.90 for the 10 measurements performed by two investigators. Conclusions. This technique can be used by surgeons and engineers for accurate analysis of the patellar resurfacing especially in patients with persistent patello-femoral problems after TKA. Declaration of Interest. (a) fully declare any financial or other potential conflict of interest

Problem. Total hip replacement (THA) is among the most common and highest total spend elective operations in the United States. However, up to 7% of patients have 90-day complications after surgery, most frequently joint dislocation that is related to poor acetabular component positioning. These complications lead to patient morbidity and mortality, as well as significant cost to the health system. As such, surgeons and hospitals value navigation technology, but existing solutions including robotics and optical navigation are costly, time-consuming, and complex to learn, resulting in limited uptake globally. Solution. Augmented reality represents a navigation solution that is rapid, accurate, intuitive, easy to learn, and does not require large and costly equipment in the operating room. In addition to providing cutting edge technology to specialty orthopedic centers, augmented reality is a very attractive solution for lower volume and smaller operative settings such as ambulatory surgery centers that cannot justify purchases of large capital equipment navigation systems. Product. HipInsight™ is an augmented reality solution for navigation of the acetabular component in THA. HipInsight is a navigation solution that includes preoperative, cloud based surgical planning based on patient imaging and surgeon preference of implants as well as intraoperative guidance for placement of the acetabular component. Once the patient specific surgical plan is generated on the cloud-based planning system, holograms showing the optimal planned position of the acetabular component are exported in holographic format to a Microsoft HoloLens 2™, which the surgeon wears during placement of the acetabular component in total hip arthroplasty. The pelvis is registered using the HipXpert™ mechanical registration device, which takes 2–3 minutes to dock in the operating room. The surgeon then is able to view the patient's anatomy and optimal placement of the acetabular component under the skin in augmented reality. The surgeon then aligns the real cup impactor with the augmented reality projection of the cup impactor resulting in precise placement of the cup. Timescales. HipInsight was FDA cleared on January 28, 2021 for intraoperative use for placement of the acetabular component in total hip arthroplasty. The first case was performed in February 2021, and the product was launched to a select group of orthopedic surgeons in March 2021. Funding. HipInsight has been self-funded to date, and is beginning to engage in discussions to raise capital for a rapidly scaling commercial launch

Damage to and repair of the acetabular labral-chondral complex are areas of clinical interest in the treatment of young adults with pain in the hip and in the prevention of degenerative arthritis of the hip. There are varying theories as to why most acetabular tears are located anterosuperiorly. We have studied the prenatal development of the human acetabular labral-chondral complex in 11 fetal hips, aged from eight weeks of gestation to term. There were consistent differences between the anterior and posterior acetabular labral-chondral complex throughout all ages of gestation. The anterior labrum had a somewhat marginal attachment to the acetabular cartilage with an intra-articular projection. The posterior labrum was attached and continuous with the acetabular cartilage. Anteriorly, the labral-chondral transition zone was sharp and abrupt, but posteriorly it was gradual and interdigitated. The collagen fibres of the anterior labrum were arranged parallel to the labral-chondral junction, but at the posterior labrum they were aligned perpendicular to the junction. We believe that in the anterior labrum the marginal attachment and the orientation of the collagen fibres parallel to the labral-chondral junction may render it more prone to damage than the posterior labrum in which the collagen fibres are anchored in the acetabular cartilage. The anterior intra-articular projection of the labrum should not be considered to be a pathological feature

Introduction. The most common method for accurate kinematic analysis of the knee arthroplasty uses bi-planar fluoroscopy and model-based RSA. The main challenge is to have access to reverse-engineered CAD models of the implant components, if not provided by the company, making this method impractical for a clinical study involving many types or sizes of implants. An alternative could be to reconstruct the 3D primitive features of the implant, such as cylindrical pegs, flat surfaces and circular boundaries, based on their 2D projections. This method was applied by Kaptein et al. (2006) for hip implants. However, despite its broad potential, it has not yet been applied for studying TKA kinematics. This study develops a methodology for feature-based RSA of TKA and investigates the range of accuracies in comparison to model-based RSA. Methods. Joint-3D software was developed in the MATLAB programming language to segment and fit elementary 2D features such as circles, lines, and ellipses to the edges of the parts on the radiographs (Figure 1). The software has the capability to reconstruct the 3D location and orientation of the components based on their 2D projections. To test the accuracy of the system a standard primary knee replacement system (Zimmer NexGen) was implanted on bone replica models, and positioned at 0° to 120° flexion at 30° intervals, simulating a lunge activity. For each pose, a multi-planar radiography system developed in our lab (Amiri et al., 2011) was used to take a sagittal and a 15° distally rotated radiograph (Figure 2a). Figure 1 shows the features C, L, and E segmented on the tibia and femur. The 3D reconstruction is performed based on a number of functions: Functions ‘f’ and ‘g’ reconstruct a 3D point or line based on their 2D projections. Function ‘h’ finds the plane containing the 3D circular edge based on its two projection ellipses. Function ‘i’ finds the 3D location of a line based on one projection line, and a known 3D vector normal to the solution 3D line. Based on these, the coordinate systems of the components were reconstructed (Figure 2b):. Femur_Origin=f(C1A,C1B);. Femur_Anteroposterior=g(L1A, L1B);. Femur_Proximodistal=g(L2A,L2B);. Femur_Mediolateral=i(L,C1A–C1B),{L=L1: if flexion<45°; L=L2: if flexion>45°};. E_3D=h(E1A,E1B);. Tibia_Origin=f(E1A_Centre,E1B_Centre);. Tibia_Anteroposterior=g(L3A,L3B);. Tibia_Mediolateral=cross(E_3D, Tibia_Anteroposterior);. Tibia_Proximodistal=cross(Tibia_Anteroposterior, Tibia_Mediolateral). To determine the errors, model-based RSA measures were used as the reference using the reverse-engineered models of the components in JointTrack software (University of Florida). Results. The overall accuracies in terms of bias (the mean error) and precision (standard deviation of the errors) are shown in Figure 3. The bias was within 0.5–1 mm and 0.9–1.2°, and the calculated precision was in the range of 0.4–0.6 mm and 0.7–1.0°. The overall accuracy was 0.8±0.6 mm and 1±0.7°. Discussion. The very good accuracies obtained show the practicality of the methodology. The methodology can be easily worked out for any type of implant based on the primitive geometric features at the bone-implant interface. This method can be extremely useful in a large clinical study by eliminating the need for having the 3D models of many types and sizes of the implant available

Objectives. The Attune total knee arthroplasty (TKA) has been used in over 600 000 patients worldwide. Registry data show good clinical outcome; however, concerns over the cement-tibial interface have been reported. We used retrieval analysis to give further insight into this controversial topic. Methods. We examined 12 titanium (Ti) PFC Sigma implants, eight cobalt-chromium (CoCr) PFC Sigma implants, eight cobalt-chromium PFC Sigma rotating platform (RP) implants, and 11 Attune implants. We used a peer-reviewed digital imaging method to quantify the amount of cement attached to the backside of each tibial tray. We then measured: 1) the size of tibial tray thickness, tray projections, peripheral lips, and undercuts; and 2) surface roughness (Ra) on the backside and keel of the trays. Statistical analyses were performed to investigate differences between the two designs. Results. There was no evidence of cement attachment on any of the 11 Attune trays examined. There were significant differences between Ti and CoCr PFC Sigma implants and Attune designs (p < 0.05); however, there was no significant difference between CoCr PFC Sigma RP and Attune designs (p > 0.05). There were significant differences in the design features between the investigated designs (p < 0.05). Conclusion. The majority of the earliest PFC Sigma designs showed evidence of cement, while all of the retrieved Attune trays and the majority of the RP PFC trays in this study had no cement attached. This may be attributable to the design differences of these implants, in particular in relation to the cement pockets. Our results may help explain a controversial aspect related to cement attachment in a recently introduced TKA design. Cite this article: A. Cerquiglini, J. Henckel, H. Hothi, P. Allen, J. Lewis, A. Eskelinen, J. Skinner, M. T. Hirschmann, A. J. Hart. Analysis of the Attune tibial tray backside: A comparative retrieval study. Bone Joint Res 2019;8:136–145. DOI: 10.1302/2046-3758.83.BJJ-2018-0102.R2

Abstract. OBJECTIVE. Flattening of the talar dome is observed clinically in haemarthropathy as structural and functional changes advance but has not been quantified yet. In order to confirm clinical observation, and assess the degree of change, morphological measurements were derived from MR images. METHODS. Four measurements were taken, using ImageJ (1.52v), from sagittal MRI projections at three locations – medial, lateral and central: Trochlear Tali Arc Length (TaAL), Talar Height (TaH), Trochlear Tali Length (TaL), and Trochlear Tali Radius (TaR). These measurements were used to generate three ratios of interest: TaR:TaAL, TaAL:TaL, and TaL:TaH. With the hypothesis of a flattening of the talar dome with haemarthropathy, it was expected that TaR:TaAL and TaL:TaH should be greater for haemophilic ankles, and TaAL:TaL should be smaller. A total of 126 MR images (ethics: MEEC 18–022) were included to assess the difference in those ratios between non-diseased ankles (33 images from 11 volunteers) and haemophilic ankles (93 images from 8 patients’ ankles). Non-diseased control measurements were compared to literature to assess the capacity of doing measurements on MRI instead of radiographs or CT. RESULTS. Reasonable agreement was found between measurements on non-diseased ankles and those from literature, with greatest variance in TaAL. The medial talus demonstrated decreases in all dimensions with haemophilia (TaR=2.4%, TaL=14.7%, TaAL=19.5% and TaH=27.8%; t-test at p<0.05), as did the lateral talus (TaR=6.2%, TaL=6.8%, TaAL=12.0% and TaH=22.4%; t-test at p<0.05). The effect on the central talus was not significant. TaAL:TaL showed talar flattening in the medial and lateral haemophilic talus (healthy medial=1.21, lateral=1.20; haemophilic medial=lateral=1.14). CONCLUSION. The results demonstrate non-uniform increased influence of haemarthropathy at the medial and lateral talar extremes, with relatively healthy measurements seen in the centre. The degree of morphological change is however progressive, differing with each haemophilic ankle. Declaration of Interest. (b) declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported:I declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project

Consecutive case series. To evaluate the efficacy of a strict stepwise radioanatomical procedure protocol in avoiding neurological complications through tool malplacement in fluoroscopy guided percutaneous procedures of the thoracic spine. Fluoroscopy guided percutaneous access to thoracic vertebral bodies is technically demanding. There is a trend towards computed tomography (CT) guidance on grounds of perceived lesser risk of spinal canal instrument malplacement. CT is however not always readily accessible and a safe technique for fluoroscopy guided procedures therefore desirable. 350 consecutive fluoroscopy guided percutaneous procedures (biopsy, vertebroplasty or kyphoplasty) covering all thoracic vertebral levels T1-T12 were performed according to a strict stepwise radioanatomical protocol. The crucial step of the protocol was not to advance the tool beyond the anterior-posterior (ap) projection of the medial pedicle wall until the tip of the instrument had been verified to have reached the posterior vertebral cortex in the lateral projection. The neurological status of patients was assessed through clinical examination prior to, immediately after the procedure and before discharge. Percutaneous instrument placement in the targeted thoracic vertebral body was achieved in all cases and the stepwise radioanatomical protocol was followed in all cases. There was no case of neurological deterioration in the case series. Conclusion: Attention to radiographic landmarks, specifically not crossing the ap projection of the medial pedicle cortex prior to reaching the posterior vertebral wall in the lateral projection, allows neurologically safe performance of fluoroscopy guided percutaneous procedures of the thoracic spine. This simple protocol is particularly useful when access to CT is limited

The incidence of osteoarthritis (OA) is increasing in our younger population. OA development early in life is often related to cartilage damage, caused by (sport) injury or trauma. Detection of early knee OA is therefore crucial to target early treatment. However, early markers for OA prognosis or diagnosis are lacking. Hoffa's fat pad (HFP) is an emerging source for knee biomarkers, as it is easily accessible and shows important interaction with the homeostasis of the knee. In this study, we used Matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI) as a first approach. MALDI-MSI allows the study of tissue-specific molecular distributions. Therefore, we used MALDI-MSI to analyze the lipid profiles in the HFP of three patients with OA and three patients undergoing cartilage regenerative treatment. We demonstrate that the lipid profile of patients with OA is different from patients with cartilage defects. HFP of each patient were snap frozen directly after surgical resection and cryosectioned at 15 μm. Each slide was sublimed with Norharmane matrix and analyzed by MALDI-MSI in positive and negative ion modes at a lateral resolution of 50 μm on a RapifleX Tissue Typer. The difference between patient groups were analyzed using principle component analysis and linear discriminant analysis. Lipid identifications were obtained on an Orbitrap Elite™ Hybrid Ion Trap-Orbitrap Mass Spectrometer in data dependent acquisition mode and analyzed using Lipostar software. Linear discriminant analysis showed a specific lipid profile for each group (variance 33.94%). Score projections revealed a differential lipid spatial distribution of OA patients compared to cartilage defect patients. Among the lipids that differed significantly, for instance, the m/z 760.59 [M+H]. +. was associated to osteoarthritis and identified as glycerophospholipid (PC 34:1), a main component of biological membranes. Additionally, the samples were found to be intra-tissue heterogeneous, with molecular profiles found in adipose-, connective- and synovial tissue. These results suggest that lipid profiles in HFP could be useful for early OA detection. However, intra-tissue heterogeneity in HFP should be recognized when using HFP as a biomarker source

The understanding of rotational alignment of the distal femur is essential in total knee replacement to ensure that there is correct placement of the femoral component. Many reference axes have been described, but there is still disagreement about their value and mutual angular relationship. Our aim was to validate a geometrically-defined reference axis against which the surface-derived axes could be compared in the axial plane. A total of 12 cadaver specimens underwent CT after rigid fixation of optical tracking devices to the femur and the tibia. Three-dimensional reconstructions were made to determine the anatomical surface points and geometrical references. The spatial relationships between the femur and tibia in full extension and in 90° of flexion were examined by an optical infrared tracking system. After co-ordinate transformation of the described anatomical points and geometrical references, the projection of the relevant axes in the axial plane of the femur were mathematically achieved. Inter- and intra-observer variability in the three-dimensional CT reconstructions revealed angular errors ranging from 0.16° to 1.15° for all axes except for the trochlear axis which had an interobserver error of 2°. With the knees in full extension, the femoral transverse axis, connecting the centres of the best matching spheres of the femoral condyles, almost coincided with the tibial transverse axis (mean difference −0.8°, . sd. 2.05). At 90° of flexion, this femoral transverse axis was orthogonal to the tibial mechanical axis (mean difference −0.77°, . sd. 4.08). Of all the surface-derived axes, the surgical transepicondylar axis had the closest relationship to the femoral transverse axis after projection on to the axial plane of the femur (mean difference 0.21°, . sd. 1.77). The posterior condylar line was the most consistent axis (range −2.96° to −0.28°, . sd. 0.77) and the trochlear anteroposterior axis the least consistent axis (range −10.62° to +11.67°, . sd. 6.12). The orientation of both the posterior condylar line and the trochlear anteroposterior axis (p = 0.001) showed a trend towards internal rotation with valgus coronal alignment

Pedicle screw fixation is a technically demanding procedure with potential difficulties and reoperation rates are currently on the order of 11%. The most common intraoperative practice for position assessment of pedicle screws is biplanar fluoroscopic imaging that is limited to two- dimensions and is associated to low accuracies. We have previously introduced a full-dimensional position assessment framework based on registering intraoperative X-rays to preoperative volumetric images with sufficient accuracies. However, the framework requires a semi-manual process of pedicle screw segmentation and the intraoperative X-rays have to be taken from defined positions in space in order to avoid pedicle screws' head occlusion. This motivated us to develop advancements to the system to achieve higher levels of automation in the hope of higher clinical feasibility. In this study, we developed an automatic segmentation and X-ray adequacy assessment protocol. An artificial neural network was trained on a dataset that included a number of digitally reconstructed radiographs representing pedicle screw projections from different points of view. This model was able to segment the projection of any pedicle screw given an X-ray as its input with accuracy of 93% of the pixels. Once the pedicle screw was segmented, a number of descriptive geometric features were extracted from the isolated blob. These segmented images were manually labels as ‘adequate’ or ‘not adequate’ depending on the visibility of the screw axis. The extracted features along with their corresponding labels were used to train a decision tree model that could classify each X-ray based on its adequacy with accuracies on the order of 95%. In conclusion, we presented here a robust, fast and automated pedicle screw segmentation process, combined with an accurate and automatic algorithm for classifying views of pedicle screws as adequate or not. These tools represent a useful step towards full automation of our pedicle screw positioning assessment system

Background. Artificial total knee designs have revolutionized over time, yet 20% of the population still report dissatisfaction. The standard implants fail to replicate native knee kinematic functionality due to mismatch of condylar surfaces and non-anatomically placed implantation. (Daggett et al 2016; Saigo et al 2017). It is essential that the implant surface matches the native knee to prevent Instability and soft tissue impingement. Our goal is to use computational modeling to determine the ideal shapes and orientations of anatomically-shaped components and test the accuracy of fit of component surfaces. Methods. One hundred MRI scans of knees with early osteoarthritis were obtained from the NIH Osteoarthritis Initiative, converted into 3D meshes, and aligned via an anatomic coordinate system algorithm. Geomagic Design X software was used to determine the average anterior-posterior (AP) length. Each knee was then scaled in three dimensions to match the average AP length. Geomagic's least-squares algorithm was used to create an average surface model. This method was validated by generating a statistical shaped model using principal component analysis (PCA) to compare to the least square's method. The averaged knee surface was used to design component system sizing schemes of 1, 3, 5, and 7 (fig 1). A further fifty arthritic knees were modeled to test the accuracy of fit for all component sizing schemes. Standard deviation maps were created using Geomagic to analyze the error of fit of the implant surface compared to the native femur surface. Results. The average shape model derived from Principal Component Analysis had a discrepancy of 0.01mm and a standard deviation of 0.05mm when compared to Geomagic least squares. The bearing surfaces showed a very close fit within both models with minimal errors at the sides of the epicondylar line (fig 2). The surface components were lined up posteriorly and distally on the 50 femurs. Statistical Analysis of the mesh deviation maps between the femoral condylar surface and the components showed a decrease in deviation with a larger number of sizes reducing from 1.5 mm for a 1-size system to 0.88 mm for a 7-size system (table 1). The femoral components of a 5 or 7-size system showed the best fit less than 1mm. The main mismatch was on the superior patella flange, with maximum projection or undercut of 2 millimeters. Discussion and Conclusion. The study showed an approach to total knee design and technique for a more accurate reproduction of a normal knee. A 5 to 7 size system was sufficient, but with two widths for each size to avoid overhang. Components based on the average anatomic shapes were an accurate fit on the bearing surfaces, but surgery to 1-millimeter accuracy was needed. The results showed that an accurate match of the femoral bearing surfaces could be achieved to better than 1 millimeter if the component geometry was based on that of the average femur. For any figures or tables, please contact the authors directly

Introduction. Studies show that cup malpositioning using conventional techniques occurs in 50 to 74% of cases defined. Assessment of the utility of improved methods of placing acetabular components depends upon the accuracy of the method of measuring component positioning postoperatively. The current study reports on our preliminary experience assessing the accuracy of EOS images and application specific software to assess cup orientation as compared to CT. Methods. Eighteen patients with eighteen unilateral THA had pre-operative EOS images were obtained for preoperative assessment of leg-length difference and standing pelvic tilt. All of these patients also had preoperative CT imaging for surgical navigation of cup placement. This allows us to compare cup orientation as measured by CT to cup orientation as measured using the EOS images. Application specific software modules were developed to measure cup orientation using both CT and EOS images (HipSextant Research Application 1.0.13 Surgical Planning Associates Inc., Boston, Massachusetts). Using CT, cup orientation was determined by identifying Anterior Pelvic Plane coordinate system landmarks on a 3D surface model. A multiplanar reconstruction module allows for creation of a plane parallel with the opening plane of the acetabulum and subsequent calculation of plane orientation in the AP Plane coordinate space according to Murray's definitions of operative anteversion and operative inclination. Using EOS DICOM images, spatial information from the images were used to reconstruct the fan beam projection model. Each image pair is positioned inside this projection model. Anterior Pelvic Plane coordinate points are digitized on each image and back-projected to the fan beam source. Corresponding beams are then used to compute the 3D intersection points defining the 3D position and orientation of the Anterior Pelvic Plane. Ellipses with adjustable radii were then used to define the cup border in each EOS image. By respecting the fan beam projection model, 3D planes defining the projected normal of the ellipse in each image are computed. 3D implant normal was estimated by determining 3D plane intersection lines for each image pair. Implant center points are defined by using the back-projected and intersected ellipse center beams in the image pairs (Figure 1). Results. The results are shown in Figure 2. The mean anteversion error was −0.9 degrees (SD 4.1, range −6.9 to 10.3). The mean inclination error was 1.8 (SD 2.1, range −2.9 to 8.6). All three cups with errors greater than 7 degrees were in cups with 40 or more degrees of anteversion. Discussion and Conclusion. The current study, while very preliminary, demonstrates the potential that EOS images can be used to measure cup orientation with a reasonable degree of accuracy. Accurate determination of cup orientation appears to be more challenging in cups with higher anteversion

Purpose of the study: To audit the radiological position of the tunnels following reconstruction of the anterior cruciate ligament (ACL). Methods: Postoperative radiographs were obtained on patients following ACL reconstruction in a single surgeon series. The positions of the tunnel in the femur and the tibia were measured and recorded. The tunnel positions were compared to the recommended positions as established by literature review. Lateral radiographs displaying greater than 2mm of imperfect projection in relation to the femoral condyles were noted. Results: 108 radiographs were collected from 105 patients, 60 were right knees and 48 were left. There were 88 men and 17 women. When measured along Blumensaats line from the anterior condylar surface, the femoral tunnel in the saggital plane should be found at 75% of the total anteroposterior distance, the recorded figure in this audit was 74%. Measured from the anterior edge in the saggital plane, the tibial tunnel should be found at 44% of the total tibial depth, our measurements averaged 40%. The tibial tunnel in the coronal plane should be found at 45% of the total width from the medial edge, our measurements averaged 46%. 57 (53%) of the radiographs demonstrated imperfect lateral projection of greater than 2mm. Conclusion: The position of the tunnels analyzed in this audit compare favourably with the positions recommended in the available literature. Over 50% of the lateral radiographs displayed imperfect lateral projection greater than 2mm. Imperfect lateral film projection affects the apparent position of the tunnel. Any interpretation of position as it appears on a two-dimensional image must take into account possible errors in the image

Introduction. Navigated freehand cutting (NFC) technology simplifies bone cutting in laboratory trials by directly navigating implants and power tools [1]. Experiments showed that NFC bone cutting was faster than with conventional jigs. However, most delays occurred at the start of each cut [2]. Therefore, we further reduced starting times and gained more accuracy with a NaviPen and a ‘smart’ NaviPrinter [3]. There were used to physically mark a line on the bone surface indicating where each cut should start. (Fig. 1). Further gains are targeted with our introduction of the On-Tool Marker (OTM); a touch-less laser marking technology as a standalone device or mounted on the cutting instrument (e.g. on the saw). The OTM points the desired cut by projecting a laser image on the bone. That image (usually a line or cross) changes dynamically, so that for any given cut the line projection remains stationary on the bone regardless of the relative location of the device. Materials & Methods. The OTM is a standalone wireless module composed of three main parts: a small laser projector, electronics for control and communication (WiFi), and a tracking frame. It is navigated in real-time with a Polaris tracker. Software routines on a proprietary NFC system compute its relative position to the target and dynamically re-calculate the image parameters. Such parameters are sent to the OTM for processing, image generation, and projection (Fig. 2). Bandwidth and data integrity were evaluated through bench tests. To assess accuracy of the projection, a target planar cut was defined on a flat surface (a line drawn on grid paper pasted to a navigated board), and the NFC system was fed with this geometrical information. The OTM was moved within a volume of ∼50cm in diameter (distance to the target plane from 5cm to 50cm), and at various angles up to +/− 80° (in roll, pitch and yaw). The projected line should coincide with the target line on paper regardless of the relative positioning of the OTM. Errors (target vs. projected) were measured on the grid paper. Results. Well-defined lines were projected at a rate of 17fps. Projected lines remained within +/− 2 mm from the target (average ∼0mm). Errors, largely caused by a lag in the images, were unperceivable after a fraction of a second if OTM remained still. Among different colors tested, green was the most suitable, based on brightness and visibility (Fig. 3). Discussion and Conclusion. A ‘smart’ navigated laser marker was successfully created and tested. The limited refresh speed and lag was not much of a concern, as common use would not require fast motion. However, further work will focus on improving these, and devise solutions for projection on non-planar bone models. OTM would speed the surgery more as it saves the time to use the NaviPen or the NaviPrinter. We estimate this can reach 2–3 minutes based on some preliminary experiments we conducted and not reported here. Finally, OTM can help reduce the number of instruments in surgery even further (less inventory, less sterilization, less cost and less worries)

The design of every post-surgical knee arthroplasty study begins with the question “How soon after surgery should we assess the patients?”. The consensus, based primarily upon clinical rating systems, is that patients' scores reach a plateau roughly one year after surgery, and that observations performed at that time should be indicative of the long-term behavior of the joint. This is satisfactory for long-term studies of clinical performance. However, when new devices are introduced there is a need to determine as quickly as possible if the device performs as designed. Waiting a year or more after surgery to characterize a device's performance may place additional patients at risk of receiving an inferior design, or may delay widespread availability of a superior design. The goal of this study was to assess knee arthroplasty patients at 6–12 weeks, 6 months and 1 year after surgery to determine if their tibiofemoral kinematics changed during functional activities. A total of 13 patients (7 female) were recruited from an ongoing clinical study to participate in this IRB-approved sub-study. All subjects received fixed-bearing, cemented, posterior-cruciate-retaining total knee arthroplasty of the same design from a single surgeon. Subjects averaged 69 years, 169cm tall, and 28 BMI. Subjects were studied at 6–12 weeks, at 6 months and at 12 months post-surgery, when they showed an average clinical flexion of 106°, 113° and 115°, respectively. Subjects' knees were observed using pulsed-flat-panel-fluoroscopy during three activities: lunging to maximum flexion with their foot placed on a 20cm step, kneeling to maximum flexion on a padded bench, and step-up/down on a 20cm step without progression of the contralateral limb. Model-image registration was used to register 3D geometric models of the implants with their radiographic projections based upon measured projection parameters. 3D knee kinematics were derived from the registered models, including joint angles and the antero-posterior translation of the medial and lateral condyles relative to the tibial baseplate. There were no statistically significant changes in knee kinematics between the 6–12 week and 6 month, and 6-month and 12-month visits during the kneel and lunge activities (Table 1). Similarly, there were no pair-wise differences in tibial rotation or condylar translation during the dynamic step activity at any flexion angle (Figure 1). Traditional thinking suggests studies of knee mechanics should be performed at least one year after surgery to make observations that are predictive of long-term joint function. In three different functional activities, we could not demonstrate significant changes in knee kinematics between 6–12 weeks and 6 months, nor between 6 months and 12 months. If these results can be confirmed in a larger subject cohort, and for a range of TKA designs, then functional follow-up studies of novel knee arthroplasty designs might be justified as early as 6–12 weeks after surgery, making it possible to accelerate confirmation devices are performing in patients as designed. For any figures or tables, please contact the authors directly

Peri-acetabular osteotomy is an established surgical treatment for symptomatic acetabular dysplasia in young adults. An anteroposterior radiograph of the pelvis is commonly used to assess the extent of dysplasia as well as to assess post-operative correction. Radiological prognostic factors include the lateral centre-edge angle, acetabular index, extrusion index and the acetabular version. Standing causes a change in the pelvis tilt which can alter certain radiological measurements relative to the supine position. This article discusses the radiological indices used to assess dysplasia and reviews the effects of patient positioning on these indices with a focus on assessment for a peri-acetabular osteotomy. Intra-operatively, fluoroscopy is commonly used and the implications of using fluoroscopy as a modality to assess the various radiological indices along with the effects of using an anteroposterior or posteroanterior fluoroscopic view are examined. Each of these techniques gives rise to a slightly different image of the pelvis as the final image is sensitive to the position of the pelvis and the projection of the x-ray beam. Cite this article: Bone Joint J 2014;96-B:1155–60

Total knee arthroplasty (TKA) and total hip arthroplasty (THA) are recognised and proven interventions for patients with advanced arthritis. Studies to date have demonstrated a steady increase in the requirement for primary and revision procedures. Projected estimates made for the United States show that by 2030 the demand for primary TKA will grow by 673% and for revision TKA by 601% from the level in 2005. For THA the projected estimates are 174% and 137% for primary and revision surgery, respectively. The purpose of this study was to see if those predictions were similar for England and Wales using data from the National Joint Registry and the Office of National Statistics. . Analysis of data for England and Wales suggest that by 2030, the volume of primary and revision TKAs will have increased by 117% and 332%, respectively between 2012 and 2030. The data for the United States translates to a 306% cumulative rate of increase between 2012 and 2030 for revision surgery, which is similar to our predictions for England and Wales. . The predictions from the United States for primary TKA were similar to our upper limit projections. For THA, we predicted an increase of 134% and 31% for primary and revision hip surgery, respectively. Our model has limitations, however, it highlights the economic burden of arthroplasty in the future in England and Wales as a real and unaddressed problem. This will have significant implications for the provision of health care and the management of orthopaedic services in the future. Cite this article: Bone Joint J 2015;97-B:1076–1081

Up to 20 percent of patients remain dissatisfied after primary total knee arthroplasty (TKA) surgery. Understanding the reasons for dissatisfaction post TKA may allow for better patient selection and optimized treatment for those who remain dissatisfied. The association between function, mobility and satisfaction are not well understood. The purpose of this study was to investigate the association between post-TKA satisfaction and i) pre-operative, ii) post-operative, and iii) change in knee joint function during gait. Thirty-one patients scheduled to receive primary TKA for knee osteoarthritis (OA) diagnosis were recruited and visited the Dynamics of Human Motion laboratory for instrumented walking gait analysis (using a synchronized NDI Optotrak motion capture system and AMTI force platforms in the walkway) at two time points, first within the week prior to their surgery, and second at approximately one year after surgery. At their post-operative visit, patients were asked to indicate their satisfaction with their knee prosthesis on a scale from zero to 100, with zero being totally unsatisfied and 100 being completely satisfied. Knee joint mechanics during gait at both time points were characterized by discriminant scores, the projection of their three-dimensional knee angles and moments during gait onto an existing discriminant model that was created to optimize separation of severe knee OA and healthy asymptomatic gait patterns. This discriminant model was created using data from 73 healthy participants and 73 with severe knee OA, and includes the magnitude and pattern features (captured with principal component analysis) of the knee adduction and flexion moment, and the magnitude of the knee flexion angle during gait. Larger discriminant scores indicate improved function toward healthy patterns, and smaller scores indicate more severe function. Associations between post-operative satisfaction and pre, post and change in discriminant scores were examined using Pearson correlation analyses. We also examined associations between satisfaction and pre-operative BMI, EQ5D and Oxford 12 scores, as well as changes in these scores from pre to post-TKA. Discriminant scores representing knee joint function during gait significantly improved on average after surgery (P =0.05). While overall knee joint function improved after primary TKA surgery, the amount of improvement in function was not reflected in post-operative patient satisfaction. However, the pre-operative function of the patient was negatively associated with satisfaction, indicating that patients with higher pre-operative function are overall less satisfied with their TKA surgery, regardless of any functional improvement due to the surgery. Interestingly, the only significant association with post-operative satisfaction was knee joint function, and the relationship between function and patient satisfaction following TKA appears to relate only to the baseline functional state of the patient, and not with functional improvement. This suggests that dissatisfaction post-surgery is more likely reflecting the unmet expectations of a higher functioning patient, and has implications for the need for improved understanding of pre-operative patient functional variability in TKA triage and expectation management

INTRODUCTION. An accelerometer-based portable navigation system (KneeAlign2, OrthAlign Inc., Aliso Viejo, CA) is expected to improve mechanical axis and component alignment compared to conventional instrumentation in total knee arthroplasty (TKA). However, past reports have evaluated its accuracy using only radiographic measurements. The purpose of this study was to analyze the accuracy of the KneeAlign2 system with radiography and more detailed three-dimensional (3D) CT. METHODS. We targeted 22 patients (24 knees) with severe osteoarthritis who underwent primary TKA using the KneeAlign2 system. Cemented, fixed-bearing, cruciate-retaining prostheses were implanted in all patients. We used postoperative standing-position full-length radiographic evaluation of the lower limbs to measure the hip-knee-ankle angle (HKA), frontal femoral component angle (FFC), and frontal tibial component angle (FTC). However, lower limb rotation and knee flexion could affect radiographic measurement of HKA and the component positioning angle. We used 3D bone models reconstructed from pre- and postoperative CT images to precisely analyze the 3D component positioning. For a 3D matching bone model made from these models, a 2D projection of the pre- and postoperative component positioning planes was made, and the projection angle was measured as angle error compared to the preoperative planned position (Figure 1). Average surgery time and total blood loss on postoperative day 7 were also recorded. RESULTS. There were 24 knees available for analysis. Mean HKA was 0.1° ± 2.2 varus; 16.7% of knees had coronal outliers exceeding 3°. Mean FFC was 0.9° ± 1.9 varus; 29.2% of femoral components were placed with coronal outliers exceeding 2°. Mean FTC was 1.2° ± 1.6 valgus; 20.8% of tibial components were placed with coronal outliers exceeding 2°. In 3D-CT evaluation, mean femoral coronal and sagittal alignment were 1.2° ± 1.7 varus (outliers exceeding ±2°: 37.5%) and 0.8° ± 2.4 flexion (outliers exceeding ±2°: 20.8%), respectively. Mean tibial coronal and sagittal alignment were 1.1° ± 1.4 valgus (outliers exceeding ±2°: 33.3%) and 0.1° ± 1.6 flexion (outliers exceeding ±2°: 20.8%), respectively. Average surgical time was 96 ± 7.7 minutes, and blood loss was 400 g ± 113 on postoperative day 7. CONCLUSIONS. With radiographic and 3D-CT evaluation, the mean angle error values for the femoral and tibial components were less than 2° in the coronal plane, and less than 1° in the sagittal plane. KneeAlign2 is highly accurate in positioning the femoral and tibial components in TKA. For figures/tables, please contact authors directly.

Perthes disease is a childhood disorder often resulting in femoral head deformity. Categorical/dichotomous outcomes of deformity are typical clinically, however quantitative, continuous measures, such as Sphericity Deviation Score (SDS), are critical for studying interventions. SDS uses radiographs in two planes to quantify femoral head deformity. Limitations of SDS may include non-orthogonal planes and lost details due to projections. We applied this method in 3D, with specific objectives to: 1. Develop SDS-like sphericity measures from 3D data 2. Obtain 2D and 3D sphericity for normal and Perthes hips 3. Compare slice-based (3D) and projection-based (2D) sphericity CT images of 16 normal (8 subjects) and 5 Perthes hips (4 subjects) were segmented to create 3D hip models. Ethics board approval was obtained for this study. SDS consists of roundness error (RE) in two planes and ellipsoid deformation (ED) between planes. We implemented a modified SDS which was applied to (a) orthogonal projections simulating radiographs (sagittal/coronal; 2D-mSDS), and (b) largest radii slices (sagittal/coronal; 3D-mSDS). Mean 2D-mSDS was higher for Perthes (27.2 (SD 11.4)) than normal (11.9 (SD 4.1)). Mean 3D-mSDS showed similar trends, but was higher than 2D (Perthes 33.6 (SD 5.3), normals 17.0 (SD 3.1)). Unlike 2D-mSDS, 3D-mSDS showed no overlap between groups. For Perthes hips, 2D-mSDS was consistent with SDS. For normal hips, 2D-mSDS was higher than expected (similar to Stulberg II). Projection-based (2D) measures may produce lower mSDS due to spatial averaging. Slice-based (3D) measures may better distinguish between normal and Perthes shapes, which may better differentiate effectiveness of treatments