Altered mechanical loading is a widely suggested, but poorly understood potential cause of cartilage degeneration in osteoarthritis. In rodents, osteoarthritis is induced following destabilization of the medial meniscus (DMM). This study estimates knee kinematics and contact forces in rats with DMM to gain better insight into the specific mechanisms underlying disease development in this widely-used model. Unilateral knee surgery was performed in adult male Sprague-Dawley rats (n=5 with DMM, n=5 with sham surgery). Radio-opaque beads were implanted on their femur and tibia. 8 weeks following knee surgery, rat gait was recorded using the 3D²YMOX setup (Sanctorum et al. 2019, simultaneous acquisition of biplanar XRay videos and ground reaction forces). 10 trials (1 per rat) were calibrated and processed in XMALab (Knörlein et al. 2016). Hindlimb bony landmarks were labeled on the XRay videos using transfer learning (Deeplabcut, Mathis et al. 2019; Laurence-Chasen et al. 2020). A generic OpenSim musculoskeletal model of the rat hindlimb (Johnson et al. 2008) was adapted to include a 3-degree-of-freedom knee. Inverse kinematics, inverse dynamics, static optimization of muscle forces, and joint reaction analysis were performed. In rats with DMM, knee adduction was lower compared to sham surgery. Ground reaction forces were less variable with DMM, resulting in less variability in joint external moments. The mediolateral ground reaction force was lower, resulting in lower hip adduction moment, thus less force was produced by the rectus femoris. Rats with DMM tended to break rather than propel, resulting in lower hip flexion moment, thus less force was produced by the semimembranosus. These results are consistent with lower knee contact forces in the anteroposterior and axial directions. These preliminary data indicate no overloading of the knee joint in rats with DMM, compared with sham surgery. We are currently expanding our workflow to finite element analysis, to examine mechanical cues in the cartilage of these rats (Fig1G)

Reduction of length of stay (LOS) without compromising quality of care is a trend observed in orthopaedic departments. To achieve this goal the pathway needs to be optimised. This requires team work than can be supported by e-health solutions. The objective of this study was to assess the impact of reduction in LOS on complications and readmissions in one hospital where accelerated discharge was introduced due to the pandemic. 317 patients with primary total hip and total knee replacements treated in the same hospital between October 2018 and February 2021 were included. The patients were divided in two groups: the pre-pandemic group and the pandemic group. The discharge criteria were: patient feels comfortable with going back home, patient has enough support at home, no wound leakage, and independence in activities of daily living. No face-to-face surgeon or nurse follow-up was planned. Patients’ progress was monitored via the mobile application. The patients received information, education materials, postoperative exercises and a coaching via secure chat. The length of stay (LOS) and complications were assessed through questions in the app and patients filled in standard PROMs preoperatively, at 6 weeks and 3 months. Before the pandemic, 64.8% of the patients spent 3 nights at hospital, whereas during the pandemic, 52.0% spent only 1 night. The median value changed from 3 days to 1 day. The complication rate before the pandemic of 15% dropped to 9 % during the pandemic. The readmission rate remained stable with 4% before the pandemic and 5 % during the pandemic. No difference were observed for PROMS between groups. The results of this study showed that after a hip and knee surgery, the shortening of the LOS from three to one night resulted in less complications and a stable rate of readmissions. These results are in line with literature data on enhanced recovery after hip and knee arthroplasty. The reduction of LOS for elective knee and hip arthroplasty during the pandemic period proved safe. The concept used in this study is transferable to other hospitals, and may have economic implications through reduced hospital costs

Abstract. Objectives. Magnetic resonance imaging (MRI) is one of the most widely used investigations for knee pain as it provides detailed assessment of the bone and soft tissues. The aim of this study was to report the frequency of each diagnosis identified on MRI scans of the knee and explore the relationship between MRI results and onward treatment. Methods. Consecutive MRI reports from a large NHS trust performed in 2017 were included in this study. The hospital electronic system was consulted to identify whether a patient underwent x-ray prior to the MRI, attended an outpatient appointment or underwent surgery. Results. 4466 MRI knees were performed in 2017 with 71.2% requested in primary care and 28.1% requested in secondary care. The most common diagnosis was signs of arthritis (55.2%), followed by meniscal tears (42.8%) and ACL tears (8.3%). 49.4% of patients who had an MRI attended outpatients and 15.6% underwent surgery. The rate of knee surgery was significantly higher for patients who had their scans requested in secondary care (32.9% vs 8.9%, p < 0.001). Conclusion. The rate of surgical intervention following MRI is low and given these results it seems unlikely that the scan changes practice in most cases. The rate of surgery and outpatient follow up was significantly higher in scans requested by secondary care. We urge clinicians avoid wasteful use of MRI and recommend the use of plain radiography prior to MRI where arthritis may be present

In the UK and USA in 2016 more than 263,000 primary knee replacements were performed. Around 20% of patients report chronic post-surgical pain (CPSP) at three or more months after total knee replacement (TKR). A large proportion of adults with all types of chronic musculoskeletal pain do not use services for a number of reasons, despite being in constant or daily pain. Given the high prevalence of CPSP, there is potentially a large hidden population with an unexpressed need for care, experiencing ongoing pain and disability; understanding why they do not use health services may herald further insight into why many remain dissatisfied with knee replacement surgery. The aim of this study is to understand why some people with CPSP after TKR do not access services or make little use of healthcare. We conducted face-to-face in-depth interviews with 34 patients from 2 high-volume orthopaedic hospitals in England, to investigate their experience of long-term pain after knee replacement; their knowledge and understanding of CPSP; and their decisions about consulting for CPSP. The sample size was based on achievement of saturation and participants provided written informed consent. Interviews were transcribed and analysed using an inductive thematic approach with double coding for rigor. Ethical approval for the study was granted by the West Midlands Solihull Research Ethics Committee (15/WM/0469). A core theme within the analysis suggests that participants do not seek healthcare because they believe that nothing further can be done, either by themselves or by healthcare professionals. Surgeons' satisfaction with the knee surgery and reassurances that pain would improve, left patients feeling uncertain about whether to re-consult, and some assumed that further consultation could lead to further surgery or medication, which they wish to avoid. Some participants' comorbidities took precedence over their knee pain when seeking healthcare. Others felt they had received their “share” of healthcare resources and that others were more deserving of treatment. People's descriptions of pain varied, from dull, or aching to shooting pains. Many described their pain as “discomfort” rather than pain. The majority described pain that was better than their pre-surgical pain, though others described pain that was worse, which they believed to be nerve damage. Many expressed disappointment in the outcome of their TKR. Expectations of pain varied, where most had expected some post-surgical pain, others underestimated it, and some had expected to be completely pain free following their TKR. Our analysis suggests that the reasons that some people with CPSP after TKR do not consult are varied and complex, spanning psychosocial, structural, moral, and organisational domains. There was an overriding sense that further consultation would be futile or may lead to unwanted treatment. Results suggest that improved information for patients about CPSP and appropriate post-surgical healthcare services may help patients and clinicians to manage this condition more effectively

The Cochrane Collaboration has produced five new reviews relevant to bone and joint surgery since the publication of the last Cochrane Corner These reviews are relevant to a wide range of musculoskeletal specialists, and include reviews in Morton’s neuroma, scoliosis, vertebral fractures, carpal tunnel syndrome, and lower limb arthroplasty.

Objectives. The objective of this study was to develop a test for the rapid (within 25 minutes) intraoperative detection of bacteria from synovial fluid to diagnose periprosthetic joint infection (PJI). Methods. The 16s rDNA test combines a polymerase chain reaction (PCR) for amplification of 16s rDNA with a lateral flow immunoassay in one fully automated system. The synovial fluid of 77 patients undergoing joint aspiration or primary or revision total hip or knee surgery was prospectively collected. The cohort was divided into a proof-of-principle cohort (n = 17) and a validation cohort (n = 60). Using the proof-of-principle cohort, an optimal cut-off for the discrimination between PJI and non-PJI samples was determined. PJI was defined as detection of the same bacterial species in a minimum of two microbiological samples, positive histology, and presence of a sinus tract or intra-articular pus. Results. The 16s rDNA test proved to be very robust and was able to provide a result in 97% of all samples within 25 minutes. The 16s rDNA test was able to diagnose PJI with a sensitivity of 87.5% and 82%, and a specificity of 100% and 89%, in the proof-of-principle and validation cohorts, respectively. The microbiological culture of synovial fluid achieved a sensitivity of 80% and a specificity of 93% in the validation cohort. Conclusion. The 16s rDNA test offers reliable intraoperative detection of all bacterial species within 25 minutes with a sensitivity and specificity comparable with those of conventional microbiological culture of synovial fluid for the detection of PJI. The 16s rDNA test performance is independent of possible blood contamination, culture time and bacterial species. Cite this article: V. Janz, J. Schoon, C. Morgenstern, B. Preininger, S. Reinke, G. Duda, A. Breitbach, C. F. Perka, S. Geissler. Rapid detection of periprosthetic joint infection using a combination of 16s rDNA polymerase chain reaction and lateral flow immunoassay: A Pilot Study. Bone Joint Res 2018;7:12–19. DOI: 10.1302/2046-3758.71.BJR-2017-0103.R2

Background. In-vitro testing of knee joints remains vital in the understanding of knee surgery and arthroplasty. However, based on the design philosophy of the original Oxford knee simulator, this in-vitro testing has mainly focused on squatting motion. As the activities of daily living might drastically differ from this type of motion, both from a kinematic and kinetic point of view, a new knee simulator is required that allows studying more random motion patterns. This paper describes a novel knee simulator that overcomes the limitations of traditional Oxford simulators, providing both kinematic and kinetic freedom with respect to the applied boundary conditions. Methods. This novel test simulator keeps the hip at a fixed position, only providing a single rotational degree of freedom (DOF) in the sagittal plane. In addition, the ankle holds four DOF, including all rotational DOF and the translation along the medio-lateral axis. Combining these boundary conditions leaves five independent DOF to the knee; the knee flexion angle is actively controlled through the positioning of the ankle joint in the antero-posterior and proximal-distal direction. The specimens' quadriceps muscle is actively controlled, the medial and lateral hamstrings are passively loaded. To validate the performance of this simulator, two fresh frozen specimens have been tested during normal squatting and cycling. Their kinematic patterns have been compared to relevant literature data. Results. Kinematic patterns in line with literature data are observed for the squatting motion, e.g. displaying femoral rollback for both specimens. In contrast, the kinematic patterns that are observed during cycling differ remarkably from the patterns of the squatting movement. Conclusion. The results provide confidence in the working principle of the presented knee simulator, the mechanical design and all processing steps. In addition, the remarkable differences observed in kinematic patterns between different studied motions indicate the need for broadening the research view to relevant motion patterns, beyond squatting

Anterior cruciate ligament (acl) reconstruction is one of the most commonly performed procedures in orthopedics for acl injury. While literature suggest short-term good-to-excellent functional results, a significant number of long-term studies report unexplained early oa development, regardless type of reconstruction. The present study reports the feasibility analysis and development of a clinical protocol, integrating different methodologies, able to determine which acl reconstruction technique could have the best chance to prevent oa. It gives also clinicians an effective tool to minimize the incidence of early oa. A prospective clinical trial was defined to evaluate clinical outcome, biochemical changes in cartilage, biomechanical parameters and possible development of oa. The most common reconstruction techniques were selected for this study, including hamstring single-bundle, single-bundle with extraarticular tenodesis and anatomical double-bundle. Power analysis was performed in terms of changes at cartilage level measurable by mri with t2 mapping. A sample size of 42 patients with isolated traumatic acl injury were therefore identified, considering a possible 10% to follow-up. Subjects presenting skeletal immaturity, degenerative tear of acl, other potential risk factors of oa and previous knee surgery were excluded. Included patients were randomized and underwent one of the 3 specified reconstruction techniques. The patients were evaluated pre-operatively, intra-operatively and post-operatively at 4 and 18 months of follow-up. Clinical evaluation were performed at each time using subjective scores (koos) and generic health status (sf-12). The activity level were documented (marx) as well as objective function (ikdc). Preliminary results allow to verify kinematic patterns during active tasks, including level walking, stair descending and squatting using dynamic roentgen sterephotogrammetric analysis (rsa) methodology before and after the injured ligament reconstruction. Intra-operative kinematics was also available by using a dedicated navigation system, thus to verify knee laxity at the time of surgery. Additionally, non-invasive assessment was possible both before the reconstruction and during the whole follow-up period by using inertial sensors. Integrating 3d models with kinematic data, estimation of contact areas of stress patterns on cartilage was also possible. The presented integrate protocol allowed to acquired different types of information concerning clinical assessment, biochemical changes in cartilage and biomechanical parameters to identify which acl reconstruction could present the most chondroprotective behavior. Preliminary data showed all the potential of the proposed workflow. The study is on-going and final results will be shortly provided

For the treatment of irreparable meniscal injuries, we developed a novel multilayer meniscal scaffold, consisting of collagen, strontium and cellulose derived from Luffa Cylindirica; and we evaluated its effects on meniscal regeneration and arthritic changes in a rabbit partial meniscectomy model. The meniscus has a key role in shock absorbtion, load distribution, chondroprotection and stability of the knee joint. Meniscal injuries are one of the most common orthopedic injuries and may lead to degenerative cartilage changes and eventually osteoarthritis. Repair of the meniscal tissue is the treatment of choice for patients with a meniscus lesion, however, this is not always possible, especially for degenerative tears or injuries located on the inner avascular zone. To overcome the devastating outcomes of meniscectomy for such injuries, several materials have been developed and tried to replace the resected meniscal tissue. These scaffolds were designed primarily to relieve pain after meniscectomy, and later on were aimed to prevent osteoarthritis and cartilage damage that may develop in the future. In the quest for optimum scaffold material small intestine, tendons and other isolated tissues, collagen and polyurethane have been researched. Nevertheless, none of these materials have absolutely proven satisfying identical replacement of resected meniscal tissue. Therefore, we developed and investigated a novel multilayer meniscal scaffold, consisting of collagen, strontium and cellulose derived from Luffa Cylindirica (a cucumber shaped and sized plant, known as sponge gourd). The aim of the study was to evaluate the meniscal regeneration and arthritic changes after partial meniscectomy and application of novel multilayer meniscal scaffold in a rabbit model and to compare the results with clinically used polyurethane scaffold (Actifit, Orteq Ltd, London, UK). Sixteen male, mature, NewZealand rabbits weighing between 2600–3500 g were randomly divided into three groups. All groups underwent knee surgery via a medial parapatellar approach and a reproducible 1.5-mm cylindrical defect was created in the avascular zone of the anterior horn of the medial meniscus bilaterally. Defects were filled with the polyurethane scaffold in Group 1 and novel multilayer scaffold was applied to fill the defects in Group 2(n:6). Four rabbits in Group 3 did not receive any treatment and defects were left empty. Animals were sacrified after 8 weeks and bilateral knee joints were taken for macroscopic, biomechanical, and histological analysis. No signs of inflammation or infection were observed in all animals. Macroscopic evaluation of tibial plateaus after excision of menisci was performed with digital images of inked condylar surfaces. No significant degenerative changes were detected between groups. Digital photographs of excised menisci were also obtained and surface areas were measured by a computer software (Image J version 1.46, National Institute of Health, Bethesda, MD). There was a slightly larger meniscus area in the first two groups than the no treatment group, however, this was not found significant. Indentation testing of the tibial condyle and compression tests for the relevant meniscal areas with a diameter of 3mm was also performed in all groups. Histological analysis was made and all specimens were stained with safranin O and scored according to a scoring system. In this study, the initial evaluation of novel multilayer meniscal scaffold demonstrated promising biomechanical and histological results; besides no adverse events related to scaffold material was observed

Summary. The donor-matched comparison between mesenchymal stem cells from knee infrapatellar and subcutaneous adipose tissue revealed their preferential commitment towards the chondrogenic and osteogenic lineage, respectively. These peculiarities could be relevant for the development of successful bone and cartilage cell-based applications. Introduction. Mesenchymal stem cells (MSCs) have been proposed in bone and cartilage tissue engineering applications as an alternative to terminally differentiated cells. In the present study we characterised and performed a donor-matched comparison between MSCs resident within the infrapatellar fat pad (IFP-MSCs) and the knee subcutaneous adipose tissue (ASCs) of osteoarthritic patients. These two fat depots, indeed, can be considered appealing candidates for orthopaedic cell-based therapies since they are highly accessible during knee surgery. Materials and Methods. IFP-MSCs and ASCs were obtained from 25 osteoarthritic patients undergoing total knee replacement. Undifferentiated cells were compared for their clonogenic ability and surface markers expression. Adipogenic, osteogenic and chondrogenic differentiative potentials were evaluated after IFP-MSCs and ASCs induction towards the various lineages by means of histological, biochemical and gene expression analysis of characteristic markers. Results. We found that undifferentiated IFP-MSCs and ASCs displayed a high clonogenic ability and the typical immunophenotype of MSCs (CD13. +. /CD29. +. /CD44. +. /CD73. +. /CD90. +. /CD105. +. /CD166. +. /CD31. −. /CD45. −. ), without any difference in terms of surface markers expression between these two cell populations. When both cell types were cultured in adequate adipo-, osteo- and chondro- differentiative media, IFP-MSCs and ASCs showed similar adipogenic potential, though undifferentiated ASCs had superior LEP expression compared to undifferentiated IFP-MSCs (p<0.01). ASCs showed a higher response to osteogenic induction in comparison with IFP-MSCs as demonstrated by significantly higher levels of calcified matrix deposition (p<0.05) and alkaline phosphatase activity (p<0.05). After 14 days of chondrogenic induction of cells cultured in pellets, we observed greater amounts of glycosaminoglycans (p<0.01) in IFP-MSCs pellets compared to ASCs pellets. Chondrogenic differentiation of IFP-MSCs showed also a superior gene expression of ACAN (p<0.001), SOX9, COMP (p<0.001) and COL2A1 (p<0.05) compared to ASCs. Furthermore, IFP-MSCs showed significantly lower levels of COL10A1 (p<0.05) and COL1A1 (p<0.01) and lower alkaline phosphatase release (p<0.05) compared to ASCs, supporting the hypothesis of a superior chondrogenic commitment of IFP-MSCs. Discussion/Conclusion. The observed dissimilarities between IFP-MSCs and ASCs suggest that despite similar features at the undifferentiated state, MSCs deriving from different anatomical sites within the same joint can display a specific commitment. The peculiar commitment of IFP-MSCs and ASCs towards the chondrogenic and osteogenic lineage suggests that they may be preferentially used for cartilage and bone applications, respectively

Objectives

Regenerative medicine is an emerging field aimed at the repair and regeneration of various tissues. To this end, cytokines (CKs), growth factors (GFs), and stem/progenitor cells have been applied in this field. However, obtaining and preparing these candidates requires invasive, costly, and time-consuming procedures. We hypothesised that skeletal muscle could be a favorable candidate tissue for the concept of a point-of-care approach. The purpose of this study was to characterize and confirm the biological potential of skeletal muscle supernatant for use in regenerative medicine.

The human acetabulofemoral joint is commonly modelled as a pure ball-and-socket joint, but there has been no quantitative assessment of this assumption in the literature. Our aim was to test the limits and validity of this hypothesis. We performed experiments on four adult cadavers. Cortical pins, each equipped with a marker cluster, were implanted in the pelvis and the femur. Movements were recorded using stereophotogrammetry while an operator rotated the cadaver’s acetabulofemoral joint, exploiting the widest possible range of movement. The functional consistency of the acetabulofemoral joint as a pure spherical joint was assessed by comparing the magnitude of the translations of the hip joint centre as obtained on cadavers, with the centre of rotation of two metal segments linked through a perfectly spherical hinge. The results showed that the radii of the spheres containing 95% of the positions of the estimated centres of rotation were separated by less than 1 mm for both the acetabulofemoral joint and the mechanical spherical hinge.

Therefore, the acetabulofemoral joint can be modelled as a spherical joint within the considered range of movement (flexion/extension 20° to 70°; abduction/adduction 0° to 45°; internal/external rotation 0° to 30°).

We isolated multilineage mesenchymal progenitor cells from haematomas collected from fracture sites. After the haematoma was manually removed from the fracture site it was cut into strips and cultured. Homogenous fibroblastic adherent cells were obtained. Flow cytometry revealed that the adherent cells were consistently positive for mesenchymal stem-cell-related markers CD29, CD44, CD105 and CD166, and were negative for the haemopoietic markers CD14, CD34, CD45 and CD133 similar to bone-marrow-derived mesenchymal stem cells. In the presence of lineage-specific induction factors the adherent cells could differentiate in vitro into osteogenic, chondrogenic and adipogenic cells.

Our results indicate that haematomas found at a fracture site contain multilineage mesenchymal progenitor cells and play an important role in bone healing. Our findings imply that to enhance healing the haematoma should not be removed from the fracture site during osteosynthesis.