3D printing and high tibial osteotomy

High tibial osteotomy (HTO) is a relatively conservative surgical option in the management of medial knee pain. Thus far, the outcomes have been variable, and apparently worse than the arthroplasty alternatives when judged using conventional metrics, owing in large part to uncer - tainty around the extent of the correction planned and achieved. This review paper introduces the concept of detailed 3D planning of the procedure, and describes the 3D printing technology that enables the plan to be performed. The different ways that the osteotomy can be undertaken, and the varying guide designs that enable accurate regis - tration are discussed and described. The system accuracy is reported. In keeping with other assistive technologies, 3D printing enables the surgeon to achieve a preoperative plan with a degree of accuracy that is not possible using conventional instruments. With the advent of low dose CT, it has been possible to confirm that the procedure has been under - taken accurately too. HTO is the ‘ultimate’ personal intervention: the amount of correction needed for optimal offloading is not yet com - pletely understood. For the athletic person with early medial joint line over - load who still runs and enjoys life, HTO using 3D printing is an attractive option. The clinical effectiveness remains unproven

3D printing and unicompartmental knee arthroplasty

In suitable patients, unicompartmental knee arthroplasty (UKA) offers a number of advantages compared with total knee arthroplasty. However, the procedure is technically demanding, with a small tolerance for error. Assistive technology has the potential to improve the accuracy of implant positioning. This review paper describes the concept of detailed UKA planning in 3D, and the 3D printing technology that enables a plan to be delivered intraoperatively using patient-specific instrumentation (PSI). The varying guide designs that enable accurate registration are discussed and described. The system accuracy is reported. Future studies need to ascertain whether accuracy for low-volume surgeons can be delivered in the operating theatre using PSI, and reflected in improved patient reported outcome measures, and lower revision rates

Paediatric gastric organoids as a tool for disease modelling and clinical translation

Purpose: Knowledge of gastric epithelial homeostasis remains incomplete, lacking human-specific models for study. This study establishes a protocol for deriving gastric epithelial organoids from paediatric gastric biopsies, providing a platform for modelling disease and developing translational therapies. Methods: Full-thickness surgical samples and endoscopic mucosal biopsies were obtained from six patients. Gastric glands were isolated by a chemical chelation protocol and then plated in 3D culture in Matrigel® droplets in chemically defined medium. After formation, organoids were passaged by single cell dissociation or manual disaggregation. Cell composition and epithelial polarity of organoids were assessed by bright field microscopy and immunofluorescence analysis, comparing them to native paediatric gastric tissue. Results: Gastric glands were successfully isolated from all six patients who were aged 4 months to 16 years. Gastric glands from all patients sealed to form spherical gastric organoids. These organoids could be passaged by manual disaggregation or single cell dissociation, remaining proliferative up to 1 year in culture. Organoids retained normal epithelial cell polarity, with the apical surface orientated towards the central lumen. Organoids expressed markers of mature gastric epithelial cell types, except for parietal cells. Conclusion: Gastric organoids can be reliably generated from paediatric biopsies and are a representative in vitro model for studying gastric epithelium

The revision partial knee classification system: understanding the causative pathology and magnitude of further surgery following partial knee arthroplasty.

AIMS: Joint registries classify all further arthroplasty procedures to a knee with an existing partial arthroplasty as revision surgery, regardless of the actual procedure performed. Relatively minor procedures, including bearing exchanges, are classified in the same way as major operations requiring augments and stems. A new classification system is proposed to acknowledge and describe the detail of these procedures, which has implications for risk, recovery, and health economics. METHODS: Classification categories were proposed by a surgical consensus group, then ranked by patients, according to perceived invasiveness and implications for recovery. In round one, 26 revision cases were classified by the consensus group. Results were tested for inter-rater reliability. In round two, four additional cases were added for clarity. Round three repeated the survey one month later, subject to inter- and intrarater reliability testing. In round four, five additional expert partial knee arthroplasty surgeons were asked to classify the 30 cases according to the proposed revision partial knee classification (RPKC) system. RESULTS: Four classes were proposed: PR1, where no bone-implant interfaces are affected; PR2, where surgery does not include conversion to total knee arthroplasty, for example, a second partial arthroplasty to a native compartment; PR3, when a standard primary total knee prosthesis is used; and PR4 when revision components are necessary. Round one resulted in 92% inter-rater agreement (Kendall's W 0.97; p < 0.005), rising to 93% in round two (Kendall's W 0.98; p < 0.001). Round three demonstrated 97% agreement (Kendall's W 0.98; p < 0.001), with high intra-rater reliability (interclass correlation coefficient (ICC) 0.99; 95% confidence interval 0.98 to 0.99). Round four resulted in 80% agreement (Kendall's W 0.92; p < 0.001). CONCLUSION: The RPKC system accounts for all procedures which may be appropriate following partial knee arthroplasty. It has been shown to be reliable, repeatable and pragmatic. The implications for patient care and health economics are discussed. Cite this article: Bone Jt Open 2021;2(8):638-645

Predicting hip-knee-ankle and femorotibial angles from knee radiographs with deep learning

BACKGROUND: Knee alignment affects the development and surgical treatment of knee osteoarthritis. Automating femorotibial angle (FTA) and hip-knee-ankle angle (HKA) measurement from radiographs could improve reliability and save time. Further, if HKA could be predicted from knee-only radiographs then radiation exposure could be reduced and the need for specialist equipment and personnel avoided. The aim of this research was to assess if deep learning methods could predict FTA and HKA angle from posteroanterior (PA) knee radiographs. METHODS: Convolutional neural networks with densely connected final layers were trained to analyse PA knee radiographs from the Osteoarthritis Initiative (OAI) database. The FTA dataset with 6149 radiographs and HKA dataset with 2351 radiographs were split into training, validation, and test datasets in a 70:15:15 ratio. Separate models were developed for the prediction of FTA and HKA and their accuracy was quantified using mean squared error as loss function. Heat maps were used to identify the anatomical features within each image that most contributed to the predicted angles. RESULTS: High accuracy was achieved for both FTA (mean absolute error 0.8°) and HKA (mean absolute error 1.7°). Heat maps for both models were concentrated on the knee anatomy and could prove a valuable tool for assessing prediction reliability in clinical application. CONCLUSION: Deep learning techniques enable fast, reliable and accurate predictions of both FTA and HKA from plain knee radiographs and could lead to cost savings for healthcare providers and reduced radiation exposure for patients

Dose-response of sodium bicarbonate ingestion highlights individuality in time course of blood analyte responses

To defend against hydrogen cation accumulation and muscle fatigue during exercise, sodium 20 bicarbonate (NaHCO3) ingestion is commonplace. The individualised dose-response relationship 21 between NaHCO3 ingestion and blood biochemistry is unclear. The present study investigated the 22 bicarbonate, pH, base excess and sodium responses to NaHCO3 ingestion. Sixteen healthy males (23±2 23 years; 78.6±15.1 kg) attended three randomised order-balanced, non-blinded sessions, ingesting a single 24 dose of either 0.1, 0.2 or 0.3 g.kg-1BM of NaHCO3 (Intralabs, UK). Fingertip capillary blood was 25 obtained at baseline and every 10 min for 1 h, then every 15 min for a further 2 h. There was a significant 26 main effect of both time and condition for all assessed blood analytes (P≤0.001). Blood analyte 27 responses were significantly lower following 0.1 g.kg-1BM compared with 0.2 g.kg-1BM; bicarbonate 28 concentrations and base excess were highest following ingestion of 0.3 g.kg-1BM (P≤0.01). Bicarbonate 29 concentrations and pH significantly increased from baseline following all doses; the higher the dose the 30 greater the increase. Large inter-individual variability was shown in the magnitude of the increase in 31 bicarbonate concentrations following each dose (+2.0-5; +5.1-8.1; and +6.0-12.3 mmol·L-1 for 0.1, 0.2 32 and 0.3 g.kg-1BM) and in the range of time to peak concentrations (30-150; 40-165; and 75-180 min for 33 0.1, 0.2 and 0.3 g.kg-1BM). The variability in bicarbonate responses was not affected by normalisation 34 to body mass. These results challenge current practices relating to NaHCO3 supplementation and clearly 35 show the need for athletes to individualise their ingestion protocol and trial varying dosages prior to 36 competition

Carnosine in health and disease

Carnosine was originally discovered in skeletal muscle, where it exists in larger amounts than in other tissues. The majority of research into the physiological roles of carnosine have been conducted on skeletal muscle. Given this and the potential for muscle carnosine content to be increased with supplementation, there is now a large body of research examining the ergogenic effects (or otherwise) of carnosine. More recent research, however, points towards a potential for carnosine to exert a wider range of physiological effects in other tissues, including the brain, heart, pancreas, kidney and cancer cells. Taken together, this is suggestive of a potential for carnosine to have therapeutic benefits in health and disease, although this is by no means without complication. Herein we will provide a review of the current literature relating to the potential therapeutic effects of carnosine in health and disease

The accuracy of statistical shape models in predicting bone shape: a systematic review

Background This systematic review aims to ascertain how accurately 3D models can be predicted from two-dimensional (2D) imaging utilising statistical shape modelling. Methods A systematic search of published literature was conducted in September 2022. All papers which assessed the accuracy of 3D models predicted from 2D imaging utilising statistical shape models and which validated the models against the ground truth were eligible. Results 2127 papers were screened and a total of 34 studies were included for final data extraction. The best overall achievable accuracy was 0.45 mm (root mean square error) and 0.16 mm (average error). Conclusion Statistical shape modelling can predict detailed 3D anatomical models from minimal 2D imaging. Future studies should report the intended application domain of the model, the level of accuracy required, the underlying demographics of subjects, and the method in which accuracy was calculated, with root mean square error recommended if appropriate

Functional flexibility: The potential of morphing composites

From plants tracking the sun to the aerodynamics of bird wings, shape change is key to the performance of natural structures. After years of reliance on mechanical joints, human engineering now focuses on improving aerodynamic efficiency through smooth, full form changes in material geometry, achieved using technologies such as morphing composites. Promising improved power generation and efficiency in wind turbines and safer more sustainable aircraft and cars, these materials can achieve both large geometric changes with low energy requirements by cycling between several stable physical states and more gradual changes in geometry by exploiting coefficient of thermal expansion mismatch and structural anisotropy, shape memory polymers and 4D printing. The merits and limitations of these various shape change systems are the subject of extensive and ongoing academic research and both commercial and defence industry trials to improve the viability of these technologies for widespread adoption. Shape change capabilities are often associated with problems in material cost, mass, mechanical properties, manufacturability, and energy requirements. Nonetheless, the considerable and rapid advances in this technology, already resulting in successful trials in advanced civilian and military aircraft and high-performance cars, indicate that future research and development of this materials platform could revolutionise many of our most critical power generation, defence and transport systems

Are there valid proxy measures of clinical behaviour?

Background: Accurate measures of health professionals' clinical practice are critically important to guide health policy decisions, as well as for professional self-evaluation and for research-based investigation of clinical practice and process of care. It is often not feasible or ethical to measure behaviour through direct observation, and rigorous behavioural measures are difficult and costly to use. The aim of this review was to identify the current evidence relating to the relationships between proxy measures and direct measures of clinical behaviour. In particular, the accuracy of medical record review, clinician self-reported and patient-reported behaviour was assessed relative to directly observed behaviour. Methods: We searched: PsycINFO; MEDLINE; EMBASE; CINAHL; Cochrane Central Register of Controlled Trials; science/social science citation index; Current contents (social & behavioural med/clinical med); ISI conference proceedings; and Index to Theses. Inclusion criteria: empirical, quantitative studies; and examining clinical behaviours. An independent, direct measure of behaviour (by standardised patient, other trained observer or by video/audio recording) was considered the 'gold standard' for comparison. Proxy measures of behaviour included: retrospective self-report; patient-report; or chart-review. All titles, abstracts, and full text articles retrieved by electronic searching were screened for inclusion and abstracted independently by two reviewers. Disagreements were resolved by discussion with a third reviewer where necessary. Results: Fifteen reports originating from 11 studies met the inclusion criteria. The method of direct measurement was by standardised patient in six reports, trained observer in three reports, and audio/video recording in six reports. Multiple proxy measures of behaviour were compared in five of 15 reports. Only four of 15 reports used appropriate statistical methods to compare measures. Some direct measures failed to meet our validity criteria. The accuracy of patient report and chart review as proxy measures varied considerably across a wide range of clinical actions. The evidence for clinician self-report was inconclusive. Conclusion: Valid measures of clinical behaviour are of fundamental importance to accurately identify gaps in care delivery, improve quality of care, and ultimately to improve patient care. However, the evidence base for three commonly used proxy measures of clinicians' behaviour is very limited. Further research is needed to better establish the methods of development, application, and analysis for a range of both direct and proxy measures of behaviour