(Background) Inertial Measurement Units (IMUs) provide a low-cost, portable solution to obtain functional measures similar to those captured with three-dimensional gait analysis, including spatiotemporal gait characteristics. The primary aim of this study was to determine the feasibility of a remote patient monitoring (RPM) workflow using ankle-worn IMUs measuring impact load, limb impact load asymmetry and knee range of motion in combination with patient-reported outcome measures. (Methods) A pilot cohort of 14 patients undergoing primary knee arthroplasty for osteoarthritis was prospectively enrolled. RPM in the community was performed weekly from 2 up to 6 weeks post-operatively using wearable IMUs. The following data were collected using IMUs: mobility (Bone Stimulus and cumulative impact load), impact load asymmetry and maximum knee flexion angle. In addition, scores from the Oxford Knee Score (OKS), EuroQol Five-dimension (EQ-5D) with EuroQol visual analogue scale (EQ-VAS) and 6 Minute Walk Test were collected. (Results) On average, the Bone Stimulus and cumulative impact load improved 52% (p = 0.002) and 371% (p = 0.035), compared to Post-Op Week 2. The impact load asymmetry value trended (p = 0.372) towards equal impact loading between the operative and non-operative limb. The mean maximum flexion angle achieved was 99.25° at Post-Operative Week 6, but this was not significantly different from pre-operative measurements (p = 0.1563). There were significant improvements in the mean EQ-5D (0.20; p = 0.047) and OKS (10.86; p < 0.001) scores both by 6 weeks after surgery, compared to pre-operative scores. (Conclusions) This pilot study demonstrates the feasibility of a reliable and low-maintenance workflow system to remotely monitor post-operative progress in knee arthroplasty patients. Preliminary data indicate IMU outputs relating to mobility, impact load asymmetry and range of motion can be obtained using commercially available IMU sensors. Further studies are required to directly correlate the IMU sensor outputs with patient outcomes to establish clinical significance.

Purpose Intra-articular administration of tranexamic acid (TXA) in orthopaedic arthroplasty and arthroscopic procedures has become increasingly common over the past decade. However, several recent reports have shown that TXA has the potential to be cytotoxic to cartilage, tendon and synovium. Our aim was to review the literature for evidence of toxic efects from TXA exposure to intra-articular tissue. Methods A scoping review methodology was used to search for studies assessing the toxic efects of TXA exposure to intra-articular tissues. MEDLINE, EMBASE, SCOPUS and The Cochrane Library were searched. Relevant information was extracted and synthesis of the retrieved data followed a basic content analytical approach. Results A total of 15 laboratory studies were retrieved. No clinical studies reporting a toxic efect of TXA on intra-articular tissue were identiied in our search. Studies were analysed according to species of origin, tissue of origin and study setting (in vitro, ex vivo, or in vivo). There was increasing cytotoxicity to chondrocytes, tenocytes, synoviocytes and periosteumderived cells with TXA concentrations beyond 20 mg/ml. Monolayer cell cultures appear more susceptible to TXA exposure, than three-dimensional and explant culture models. In vivo studies have not demonstrated a major toxic efect. Conclusions Current evidence suggests a dose-dependent toxic efect on cartilage, tendon, and synovial tissue. Concentrations of 20 mg/ml or less are expected to be safe. There is a signiicant body of evidence to suggest the need for caution with intraarticular administration of TXA. There is a need for further human clinical trials in order to clarify the long-term safety of TXA topical application. AbbreviationsTXA Tranexamic acid IV Intravenous PRISMA-ScR Preferred reporting items for systematic reviews and meta-analyses extension for scoping reviews ECM Extracellular matrix 2D Two-dimensional 3D Three-dimensional LDH Lactate dehydrogenase

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