Focal Defects Research Articles

Detection and Characterization of Endplate Structural Defects on CT: A Diagnostic Accuracy Study.

Diagnostic test study. To determine the reliability and validity or diagnostic accuracy of two previously described endplate structural defect (EPSD) assessment methods. Studies of EPSD may further the understanding of pathoanatomic mechanisms underlying back pain. However, clinical imaging methods used to document EPSD have not been validated, leaving uncertainty about what the observations represent. Using an evaluation manual, 418 endplates on CT sagittal slices obtained from 19 embalmed cadavers (9 men and 10 women, aged 62-91yr) were independently assessed by two experienced radiologists and a novice for EPSD using the two methods. The corresponding micro-CT (µCT) from the harvested T7-S1 spines were assessed by another independent rater with excellent intra-rater reliability (k=0.96). Inter-rater reliability was good for the presence (k=0.60-0.69) and fair for specific phenotypes (k=0.43-0.58) of EPSD. Erosion, for which the Brayda-Bruno classification lacked a category, was mainly (82.8%) classified as wavy/irregular, while many notched defects (n=15, 46.9%) and Schmorl's nodes (n=45, 79%) were recorded as focal defects using Feng's classification. When compared to µCT, endplate fractures (n=53) and corner defects (n=28) were routinely missed on CT. Endplates classified as wavy/irregular on CT corresponded to erosion (n=29, 21.2%), jagged defects (n=21, 15.3%), calcification (n=19, 13.9%), and other phenotypes on µCT. Some focal defects on CT represented endplate fractures (n=21, 27.6%) on µCT. Overall, with respect to the presence of an EPSD, there was a sensitivity of 70.9% and a specificity of 79.1% using Feng's method, and 79.5% and 57.5% using Brayda-Bruno's method. Poor to fair inter-rater reliability (k=0.26-0.47) was observed for defect dimensions. There was good inter-rater reliability and evidence of criterion validity supporting assessments of EPSD presence using both methods. However, neither method contained all needed EPSD phenotypes for optimal sensitivity, and specific phenotypes were often misclassified.

An Interesting Case of Posterior Reversible Encephalopathy Syndrome

Posterior Reversible Encephalopathy Syndrome (PRES) is a special type of cerebrovascular disease defined by clinical and imaging findings. The onset of PRES typically includes acute or subacute headaches, visual impairment, seizures, focal neurological defects and nonspecific symptoms such as nausea and vomiting. The purpose of this case report is to present the characteristics of these diseases in a pregnant patient with both preeclampsia and PRES, and to contribute to the literature by discussing the differential diagnosis.

Protecting the regenerative environment: selecting the optimal delivery vehicle for cartilage repair—a narrative review

Focal cartilage defects are common in youth and older adults, cause significant morbidity and constitute a major risk factor for developing osteoarthritis (OA). OA is the most common musculoskeletal (MSK) disease worldwide, resulting in pain, stiffness, loss of function, and is currently irreversible. Research into the optimal regenerative approach and methods in the setting of either focal cartilage defects and/or OA holds to the ideal of resolving both diseases. The two fundamentals required for cartilage regenerative treatment are 1) the biological element contributing to the regeneration (e.g., direct application of stem cells, or of an exogenous secretome), and 2) the vehicle by which the biological element is suspended and delivered. The vehicle provides support to the regenerative process by providing a protective environment, a structure that allows cell adherence and migration, and a source of growth and regenerative factors that can activate and sustain regeneration. Models of cartilage diseases include osteochondral defect (OCD) (which usually involve one focal lesion), or OA (which involves a more diffuse articular cartilage loss). Given the differing nature of these models, the optimal regenerative strategy to treat different cartilage diseases may not be universal. This could potentially impact the translatability of a successful approach in one condition to that of the other. An analogy would be the repair of a pothole (OCD) versus repaving the entire road (OA). In this narrative review, we explore the existing literature evaluating cartilage regeneration approaches for OCD and OA in animal then in human studies and the vehicles used for each of these two conditions. We then highlight strengths and challenges faced by the different approaches presented and discuss what might constitute the optimal cartilage regenerative delivery vehicle for clinical cartilage regeneration.

Treatment of osteochondral injuries of the humeral head using fresh osteochondral allograft transplantation

BackgroundLarge osteochondral lesions of the humeral head can result from locked posterior dislocations, avascular necrosis, and osteochondritis dissecans. Fresh osteochondral allograft (OCA) transplantation is a treatment option for young patients with focal osteochondral defects of the humeral head. The purpose of this case series was to assess graft survivorship, subjective patient-reported outcomes (PROMs), and satisfaction among seven patients who underwent OCA transplantation of the humeral head. MethodsWe identified seven patients who underwent humeral head OCA transplantation between 2008 and 2017. A custom questionnaire for patient reported outcome measures including ASES, QuickDASH, Likert satisfaction, and reoperations was mailed to each patient. Clinical failure was defined as further surgery that involved removal of the allograft. ResultsMedian follow-up duration was 10 years (range, 4.6 to 13.5 years) with a median age of 21.6 years (range, 18.5 to 43.5 years). Most patients (86%) reported improved function and reduced pain. At final follow-up, 71% of patients reported ongoing problems with their shoulder including pain, stiffness, clicking/grinding, limited range of motion, and instability. Return to recreational activities was high at 86% but 43% expressed limitations with activity due to their shoulder. Overall satisfaction was high at 71% with mean ASES and QuickDASH scores at 62.4 and 29.2 respectively. Reoperation after OCA occurred in one patient (14%). ConclusionsAmong this case series of seven patients who underwent OCA transplantation of the humeral head, patient satisfaction was high at 10 year follow-up and most returned to recreational activity although most also had persistent shoulder symptoms.

Treatment of cartilage defects in the patellofemoral joint with matrix-associated autologous chondrocyte implantation effectively improves pain, function, and radiological outcomes after 5-7 years.

The aim of the present study was to evaluate midterm outcomes 5-7years after matrix-associated autologous chondrocyte implantation (MACI) in the patellofemoral joint. Twenty-six patients who had undergone MACI using the Novocart® 3D scaffold were prospectively evaluated. Clinical outcomes were determined by measuring the 36-Item Short-Form Health Survey (SF-36) and International Knee Documentation Committee (IKDC) scores and the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) values preoperatively and 3, 6, and 12months, and a mean of 6years postoperatively. At the final follow-up, the Magnetic Resonance Observation of Cartilage Repair Tissue (MOCART) score was evaluated. Twenty-two patients with 23 focal cartilage defects (19 patella and four trochlea) were available for the final follow-up. The mean defect size was 4.0 ± 1.9 cm2 (range 2.4-9.4 cm2). All clinical outcome scores improved significantly until 5-7 years after MACI (SF-36 score, 61.2 ± 19.6 to 83.2 ± 11.6; P = 0.001; IKDC score, 47.5 ± 20.6 to 74.7 ± 15.5; P < 0.001; and WOMAC, 29.8 ± 15.7 to 8.2 ± 10.3; P < 0.001). The mean MOCART score was 76.0 ± 11.0 at the final follow-up. Nineteen of the 22 patients (86.4%) were satisfied with the outcomes after 5-7 years and responded that they would undergo the procedure again. MACI in the patellofemoral joint demonstrated good midterm clinical results with a significant reduction in pain, improvement in function, and high patient satisfaction. These clinical findings are supported by radiological evidence from MOCART scores. IV-case series.

Patellar height: an important parameter in knee MRI associated with tendinopathy, quadriceps fat pad edema (QFPE), anterior cruciate ligament mucoid degeneration (ACL-MD), and lateral cartilage damage.

Some pathologies associated with abnormal patellar height have been reported in the literature. However, its relationship with some pathologies, such as anterior cruciate ligament mucoid degeneration (ACL-MD) and focal cartilage defect, has not been investigated. To investigate the relationship between patellar height with patellar-quadriceps tendinopathy, quadriceps fat pad edema, ACL-MD, and focal cartilage defect. Magnetic resonance imaging of the knees of 261 patients were classified into three groups as normal, patella alta, and patella baja, and evaluated in terms of patellar-quadriceps tendinopathy, quadriceps fat pad edema, ACL-MD, and focal cartilage defect. There were 261 patients (140 men, 121 women; age range = 18-60 years; mean age = 30 ± 4.7 years). Of the 261 patients, 181 (69.3%) were normal, 56 (21.4%) were patella alta, and 24 were patella baja (9.1%). Patellar-quadriceps tendinopathy, quadriceps fat pad edema, and ACL-MD rates were significantly higher compared to the normal group (P <0.05). While a moderate positive correlation was found between patellar height shift and patellar-quadriceps tendinopathy and ACL-MD, there was a small correlation between patellar height shift and quadriceps fat pad edema. The rate of focal cartilage defect was significantly higher in the middle part of the lateral femoral condyle and lateral knee joint only in patella alta. The risk of patellar-quadriceps tendinopathy, quadriceps fat pad edema, ACL-MD, and lateral focal cartilage defect is higher in patients with alta-baja. The radiologist should evaluate these pathologies more carefully, especially subtle ones, in patients with abnormal patellar height.

IMPACT OF MINCING TECHNIQUES ON CHONDROCYTE VIABILITY IN BOVINE ARTICULAR CARTILAGE: A COMPARATIVE STUDY BETWEEN COMMERCIALLY AVAILABLE SHAVERS AND SCALPEL MINCING

Mincing cartilage with commercially available shavers is increasingly used for treating focal cartilage defects. This study aimed to compare the impact of mincing bovine articular cartilage using different shaver blades on chondrocyte viability.Bovine articular cartilage was harvested using a scalpel or three different shaver blades (2.5 mm, 3.5 mm, or 4.2 mm) from a commercially available shaver. The cartilage obtained with a scalpel was minced into fragments smaller than 1 mm3. All four conditions were cultivated in a culture medium for seven days. After Day 1 and Day 7, metabolic activity, RNA isolation, and gene expression of anabolic (COL2A1, ACAN) and catabolic genes (MMP1, MMP13), Live/Dead staining and visualization using confocal microscopy, and flow cytometric characterization of minced cartilage chondrocytes were measured.The study found that mincing cartilage with shavers significantly reduced metabolic activity after one and seven days compared to scalpel mincing (p&lt;0.001). Gene expression of anabolic genes was reduced, while catabolic genes were increased after day 7 in all shaver conditions. The MMP13/COL2A1 ratio was also increased in all shaver conditions. Confocal microscopy revealed a thin line of dead cells at the lesion site with viable cells below for the scalpel mincing and a higher number of dead cells diffusely distributed in the shaver conditions. After seven days, there was a significant decrease in viable cells in the shaver conditions compared to scalpel mincing (p&lt;0.05). Flow cytometric characterization revealed fewer intact cells and proportionally more dead cells in all shaver conditions compared to the scalpel mincing.Mincing bovine articular cartilage with commercially available shavers reduces the viability of chondrocytes compared to scalpel mincing. This indicates that mincing cartilage with a shaver should be considered a matrix rather than a cell therapy. Further experimental and clinical studies are required to standardize the mincing process with a shaver.Acknowledgements: This study received unrestricted funding from KARL STORZ SE &amp; Co. KG.

A SIX-MONTH STUDY OF CLINICAL SYMPTOMS, IMAGING AND OUTCOMES OF PATIENTS DIAGNOSED WITH CEREBRAL VENOUS SINUS THROMBOSIS (CVST)

Background: One of the unusual cause of headache and stroke is CVST with very diverse clinical manifestation. Onset of focal headache, headache with seizures, papilledema, or focal defect are some of important clinical features. Consideration of risk factors, especially the use of hormonal drugs, recent pregnancy, coagulation disorders, as well as recent infections and systemic inflammation, can lead to clinical suspicion of CVST. For early and accurate detection we can use modern MR imaging. Objective: To evaluate the clinical symptoms and imaging findings of patients with a diagnosis of CVST during 6-months follow-up. Methods: This cross-sectional study was used on 56 patients with CVST. Clinical, preclinical, and imaging records of inpatients and also information like age, sex, and underlying diseases were collected at a checklist. After 6 months from the start of treatment, the identified patients were followed up through a telephone interview, and if there were any positive symptoms, they were visited on an outpatient basis in the neurology clinic of Alavi Hospital in Ardabil, and the necessary information was extracted. Collected data were analyzed by statistical methods in SPSS version 21. Results: Of all patients, 47 (84%) were women. The most common symptom was headache with 87.5% and then nausea and vomiting, sensory and visual symptoms with 57.1%, 51.8% and 44.6%, respectively. Conclusion: The results of this study showed that, the clinical symptoms of patients are very various and misleading, but the most common clinical symptoms were headache, nausea and vomiting. Women were involved more than men. The results of the study disclosed that CVST had wide range of clinical manifestations and non-specific symptoms at the beginning. For that reason, in especially high risk groups for thrombosis, the diagnosis of CVST should be kept in mind.

Effects of shear-induced crystallization on the complex viscosity of lamellar-structured concentrated surfactant solutions.

Material relationships at low temperatures were determined for concentrated surfactant solutions using a combination of rheological experiments, cross-polarized microscopy, calorimetry, and small angle X-ray scattering. A lamellar structured 70 wt% solution of sodium laureth sulfate in water was used as a model system. At cold temperatures (5 °C and 10 °C), the formation of surfactant crystals resulted in extremely high viscosity. The bulk flow behavior of multi-lamellar vesicles (20 °C) and focal conic defects (90 °C) in the lamellar phase was similar. Shear-induced crystallization at temperatures higher than the equilibrium crystallization temperature range resulted in an unusual complex viscosity peak. The effects of processing-relevant parameters including temperature, cooling time, and applied shear were investigated. Knowledge of key low-temperature structure-property-processing relationships for concentrated feedstocks is essential for the sustainable design and manufacturing of surfactant-based consumer products for applications such as cold-water laundry.

Lateral Opening-Wedge Distal Femoral Osteotomy Made Easy: Tips and Tricks

A lateral opening-wedge distal femoral osteotomy is useful to offload the lateral tibiofemoral compartment for focal chondral defects or isolated lateral compartment arthritis. Although beneficial for these lateral compartment disorders, a distal femoral osteotomy requires careful forethought to optimize correction accuracy and safety. We recommend the following for effective execution of a distal femoral osteotomy: (1) Plan the desired correction preoperatively while accounting for an individual patient’s anatomy and femoral width. (2) Perform an iliotibial band Z-lengthening for large deformity corrections to not overconstrain the lateral structures. (3) Use the plate to help guide the level of the osteotomy, which will facilitate bony contact after the osteotomy and decrease plate prominence. (4) Perform the osteotomy with a saw anteriorly and an osteotome posteriorly for safety and stop the osteotomy approximately 1 cm short of the far cortex. (5) Fashion tricortical wedge grafts at the height of the planned correction to maintain reduction and facilitate plate placement. (6) Control the plate position to lie optimally at the level of the osteotomy, ensuring it is not proud and is parallel with the femoral shaft. With these presurgical and intraoperative steps, a lateral opening-wedge distal femoral osteotomy can be performed effectively.

Surgical treatment of a newborn child with congenital aplasia of the scalp

Introduction. Skin aplasia is a developmental defect represented by a skin defect of varying extent, often in combination with the defect of underlying tissues – subcutaneous fat, muscles and with various forms of dysraphy - non-closured embryonic slits. By various authors, defect frequency ranges from 1 per 1 000 to 1 per 10 000 newborns. Congenital focal aplasia of the skin and subcutaneous tissues can be located in limited areas; most often it is diagnosed on the scalp looking like single or multiple focal skin defects. Quite often, focal aplasia also affects the skin on the trunk and limbs.&#x0D; Description of observation. The article presents a clinical case of congenital focal aplasia of the scalp and skull bones in a newborn child. This type of skin congenital aplasia by I. Frieden classification corresponds to Group I of congenital aplasia of the skin with lesions on the scalp. At the expert examination with multispiral computed tomography, the absence of parietal bone was diagnosed. So, the defect bottom was dura mater. In this case, the authors considered conservative approach to be unacceptable because of long period of healing and high risk of secondary infection. The performed surgery has led to a satisfactory cosmetic result. The state of bone structures was assessed catamnetically.&#x0D; Conclusion. Modern diagnostic techniques have proven that an active surgical tactics in children with congenital aplasia of the scalp is justified.

Microscale strain concentrations in tissue-engineered osteochondral implants are dictated by local compositional thresholds and architecture

Tissue-engineered osteochondral implants manufactured from condensed mesenchymal stem cell bodies have shown promise for treating focal cartilage defects. Notably, such manufacturing techniques have shown to successfully recapture the bulk mechanical properties of native cartilage. However, the relationships among the architectural features, local composition, and micromechanical environment within tissue-engineered cartilage from cell-based aggregates remain unclear. Understanding such relationships is crucial for identifying critical parameters that can predict in vivo performance. Therefore, this study investigated the relationship among architectural features, composition, and micromechanical behavior of tissue-engineered osteochondral implants. We utilized fast-confocal microscopy combined with a strain mapping technique to analyze the micromechanical behavior under quasi-static loading, as well as Fourier Transform Infrared Spectroscopy to analyze the local compositions. More specifically, we investigated the architectural features and compositional distributions generated from tissue maturation, along with macro- and micro-level strain distributions. Our results showed that under compression, cell-based aggregates underwent deformation followed by body movement, generating high local strain around the boundaries, where local aggrecan concentration was low and local collagen concentration was high. By analyzing the micromechanics and composition at the single aggregate length scale, we identified a strong threshold relationship between local strain and compositions. Namely at the aggrecan concentration below 0.015 arbitrary unit (A.U.) and the collagen concentration above 0.15 A.U., the constructs experienced greater than threefold increase in compressive strain. Overall, this study suggests that local compositional features are the primary driver of the local mechanical environment in tissue-engineered cartilage constructs, providing insight into potential quality control parameters for manufacturing tissue-engineered constructs.

The development of a nucleus pulposus-derived cartilage analog scaffold for chondral repair and regeneration.

Focal chondral defects (FCDs) significantly impede quality of life for patients and impose severe economic costs on society. One of the most promising treatment options-autologous matrix-induced chondrogenesis (AMIC)-could benefit from a scaffold that contains both of the primary cartilage matrix components-sulfated glycosaminoglycans (sGAGs) and collagen type II. Here, 17 different protocols were evaluated to determine the most optimum strategy for decellularizing (decelling) the bovine nucleus pulposus (bNP) to yield a natural biomaterial with a cartilaginous constituency. The resulting scaffold was then characterized with respect to its biochemistry, biomechanics and cytocompatibility. Results indicated that the optimal decell protocol involved pre-crosslinking the tissue prior to undergoing decell with trypsin and Triton X-100. The residual DNA content of the scaffold was found to be 32.64 ± 9.26 ng/mg dry wt. of tissue with sGAG and hydroxyproline (HYP) contents of 72.53 ± 16.43. and 78.38 ± 8.46 μg/mg dry wt. respectively. The dynamic viscoelastic properties were found to be preserved (complex modulus: 17.92-16.62 kPa across a range of frequencies) while the equilibrium properties were found to have significantly decreased (aggregate modulus: 11.51 ± 9.19 kPa) compared to the non-decelled fresh bNP tissue. Furthermore, the construct was also found to be cytocompatible with bone marrow stem cells (BMSCs). While it was not permissive of cellular infiltration, the BMSCs were still found to have lined the laser drilled channels in the scaffold. Taken together, the biomaterial developed herein could be a valuable addition to the AMIC family of scaffolds or serve as an off-the-shelf standalone option for cartilage repair.

High contrast cartilaginous endplate imaging in spine using three dimensional dual-inversion recovery prepared ultrashort echo time (3D DIR-UTE) sequence

PurposeTo investigate the feasibility and application of a novel imaging technique, a three-dimensional dual adiabatic inversion recovery prepared ultrashort echo time (3D DIR-UTE) sequence, for high contrast assessment of cartilaginous endplate (CEP) imaging with head-to-head comparisons between other UTE imaging techniques.MethodThe DIR-UTE sequence employs two narrow-band adiabatic full passage (AFP) pulses to suppress signals from long T2 water (e.g., nucleus pulposus (NP)) and bone marrow fat (BMF) independently, followed by multispoke UTE acquisition to detect signals from the CEP with short T2 relaxation times. The DIR-UTE sequence, in addition to three other UTE sequences namely, an IR-prepared and fat-saturated UTE (IR-FS-UTE), a T1-weighted and fat-saturated UTE sequence (T1w-FS-UTE), and a fat-saturated UTE (FS-UTE) was used for MR imaging on a 3 T scanner to image six asymptomatic volunteers, six patients with low back pain, as well as a human cadaveric specimen. The contrast-to-noise ratio of the CEP relative to the adjacent structures—specifically the NP and BMF—was then compared from the acquired images across the different UTE sequences.ResultsFor asymptomatic volunteers, the DIR-UTE sequence showed significantly higher contrast-to-noise ratio values between the CEP and BMF (CNRCEP-BMF) (19.9 ± 3.0) and between the CEP and NP (CNRCEP-NP) (23.1 ± 1.7) compared to IR-FS-UTE (CNRCEP-BMF: 17.3 ± 1.2 and CNRCEP-NP: 19.1 ± 1.8), T1w-FS-UTE (CNRCEP-BMF: 9.0 ± 2.7 and CNRCEP-NP: 10.4 ± 3.5), and FS-UTE (CNRCEP-BMF: 7.7 ± 2.2 and CNRCEP-NP: 5.8 ± 2.4) for asymptomatic volunteers (all P-values < 0.001). For the spine sample and patients with low back pain, the DIR-UTE technique detected abnormalities such as irregularities and focal defects in the CEP regions.ConclusionThe 3D DIR-UTE sequence is able to provide high-contrast volumetric CEP imaging for human spines on a clinical 3 T scanner.

Prospective applications of hydrogels for the intra-articular treatment of osteoarthritis

Introduction Osteoarthritis (OA) is a degenerative disease that leads to gradual loss of cartilage and the formation of osteophytes, and consequently to joint instability, pain, and limited mobility. Treatment options include drug therapy, physiotherapy, lifestyle changes and surgery to correct or replace the joint. Intra-articular treatments, such as the injection of hydrogels modified for specific clinical tasks, are becoming increasingly popular due to their ability to provide targeted and effective relief with minimal side effects.Purpose of this study was to evaluate the use of hydrogels for the intra-articular treatment of osteoarthritis (OA) based on a review of scientific literature.Materials and methods Literature sources for the evaluation of the use of hydrogels for the intraarticular treatment of OA were selected using the subject search queries “hydrogel” AND “intra? articular” AND “osteoarthritis” in the PubMed, ScienceDirect and SciSpace databases. The search period was limited to 2018–2023 years of publication. An initial selection of articles by search glories resulted in 1,576 articles; after analysis and application of exclusion criteria, 53 of the most relevant sources were included in the review.Results Two types of hydrogels for intra-articular use have been dentified: injectable and implantable. Injectable hydrogels are used to replace synovial fluid, deliver drugs or fill focal cartilage defects. Implantable hydrogels are used to replace or repair damaged cartilage in joints affected by OA, thereby restoring surface integrity, reducing pain and improving function.Discussion Hydrogels demonstrate promise as a potential material for the treatment of OA as they offer several advantages, such as biomimicry, biocompatibility, minimally invasive administration and the ability to deliver therapeutic agents directly to the affected joint. However, there are limitations: uncontrolled degradation, low durability and a high likelihood of negative local and systemic immune reactions.Conclusion Further research is needed to optimize the design and composition of hydrogels for clinical use, including the development of new compositions with programmable properties, studying long-term effects and comparing effectiveness with other OA treatment.

ArthroNavi framework: stereo endoscope-guided instrument localization for arthroscopic minimally invasive surgeries.

As an example of a minimally invasive arthroscopic surgical procedure, arthroscopic osteochondral autograft transplantation (OAT) is a common option for repairing focal cartilage defects in the knee joints. Arthroscopic OAT offers considerable benefits to patients, such as less post-operative pain and shorter hospital stays. However, performing OAT arthroscopically is an extremely demanding task because the osteochondral graft harvester must remain perpendicular to the cartilage surface to avoid differences in angulation. We present a practical ArthroNavi framework for instrument pose localization by combining a self-developed stereo endoscopy with electromagnetic computation, which equips surgeons with surgical navigation assistance that eases the operational constraints of arthroscopic OAT surgery. A prototype of a stereo endoscope specifically fit for a texture-less scene is introduced extensively. Then, the proposed framework employs the semi-global matching algorithm integrating the matching cubes method for real-time processing of the 3D point cloud. To address issues regarding initialization and occlusion, a displaying method based on patient tracking coordinates is proposed for intra-operative robust navigation. A geometrical constraint method that utilizes the 3D point cloud is used to compute a pose for the instrument. Finally, a hemisphere tabulation method is presented for pose accuracy evaluation. Experimental results show that our endoscope achieves 3D shape measurement with an accuracy of . The mean error of pose localization is 15.4deg (range of 10.3deg to 21.3deg; standard deviation of 3.08deg) in our ArthroNavi method, which is within the same order of magnitude as that achieved by experienced surgeons using a freehand technique. The effectiveness of the proposed ArthroNavi has been validated on a phantom femur. The potential contribution of this framework may provide a new computer-aided option for arthroscopic OAT surgery.

Birefringence-derived artifact in optical coherence tomography imaging of the lamina cribrosa in eyes with glaucoma

We investigated birefringence-derived artifacts that potentially mimic focal defects of the lamina cribrosa (focal LC defects) in optical coherence tomography (OCT) imaging of eyes with glaucoma. This study included 74 eyes of 48 patients with glaucoma. Five horizontal line B-scan images of the optic disc were obtained using commercial swept-source OCT. From a dataset of prototype swept-source polarization-diversity OCT, we calculated the following types of OCT images: polarization-dependent, polarization-dependent attenuation-coefficient, polarization-independent, and polarization-independent attenuation-coefficient. We assessed the commercial OCT images for the presence of birefringence-derived artifacts by comparison with the polarization-diversity OCT images. Commercial OCT showed suggestive findings of focal LC defects in 17 of 74 eyes. Reevaluation using polarization-independent OCT revealed that the focal LC defects in one of 17 eyes (5.9%) were actually birefringence-derived artifacts. This study demonstrated the existence of birefringence-derived artifacts mimicking focal LC defects in commercial OCT imaging and indicated that polarization-diversity OCT is an effective tool to evaluate the presence of these artifacts.

Knee Cartilage Lesion Management-Current Trends in Clinical Practice.

Many patients, particularly those aged above 40, experience knee joint pain, which hampers both sports activities and daily living. Treating isolated chondral and osteochondral defects in the knee poses a significant clinical challenge, particularly in younger patients who are not typically recommended partial or total knee arthroplasty as alternatives. Several surgical approaches have been developed to address focal cartilage defects. The treatment strategies are characterized as palliation (e.g., chondroplasty and debridement), repair (e.g., drilling and microfracture), or restoration (e.g., autologous chondrocyte implantation, osteochondral autograft, and osteochondral allograft). This review offers an overview of the commonly employed clinical methods for treating articular cartilage defects, with a specific focus on the clinical trials conducted in the last decade. Our study reveals that, currently, no single technology fully meets the essential requirements for effective cartilage healing while remaining easily applicable during surgical procedures. Nevertheless, numerous methods are available, and the choice of treatment should consider factors such as the location and size of the cartilage lesion, patient preferences, and whether it is chondral or osteochondral in nature. Promising directions for the future include tissue engineering, stem cell therapies, and the development of pre-formed scaffolds from hyaline cartilage, offering hope for improved outcomes.

Photo-Cross-Linkable, Injectable, and Highly Adhesive GelMA-Glycol Chitosan Hydrogels for Cartilage Repair.

Hydrogels provide a promising platform for cartilage repair and regeneration. Although hydrogels have shown some efficacy, they still have shortcomings including poor mechanical properties and suboptimal integration with surrounding cartilage. Herein, hydrogels that are injectable, cytocompatible, mechanically robust, and highly adhesive to cartilage are developed. This approach uses GelMA-glycol chitosan (GelMA-GC) that is crosslinkable with visible light and photoinitiators (lithium acylphosphinate and tris (2,2'-bipyridyl) dichlororuthenium (II) hexahydrate ([RuII(bpy)3 ]2+ and sodium persulfate (Ru/SPS)). Ru/SPS-cross-linked hydrogels have higher compressive and tensile modulus, and most prominently higher adhesive strength with cartilage, which also depends on inclusion of GC. Tensile and push-out tests of the Ru/SPS-cross-linked GelMA-GC hydrogels demonstrate adhesive strength of ≈100 and 46kPa, respectively. Hydrogel precursor solutions behave in a Newtonian manner and are injectable. After injection in focal bovine cartilage defects and in situ cross-linking, this hydrogel system remains intact and integrated with cartilage following joint manipulation ex vivo. Cells remain viable (>85%) in the hydrogel system and further show tissue regeneration potential after three weeks ofin vitroculture. These preliminary results provide further motivation for future research on bioadhesive hydrogels for cartilage repair and regeneration.

Objective detection of visual field defects with multifrequency VEPs.

To correlate multifrequency pattern reversal VEPs in quadrants (QmfrVEPs) with perimetric field losses for objective detection of visual field losses. QmfrVEP measurements were performed using four LED-based checkerboard stimulators to stimulate the four quadrants of the visual field. QmfrVEPs were measured monocularly in 5 normal subjects and in 5 glaucoma patients who showed losses in conventional Octopus perimetry. The pattern reversal frequency varied slightly between the stimulators: (11.92, 12.00, 12.08 and 12.16 reversals/sec). The responses to the different stimuli were identified by discrete Fourier analysis. VEPs were recorded using different electrode configurations, and the recording with the highest signal-to-noise ratio (SNR) was used for further analysis. QmfrVEP responses from the different quadrants can be reliably measured and separated using the 0.08 reversals/sec interstimulus reversal frequency differences. The signal-to-noise ratio in the four quadrants was significantly correlated with the equivalent visual field losses obtained with perimetry (Spearman rank correlation: P < 0.001). In the five glaucoma patients, the SNR was reduced in 15 out of the 16 quadrants with a perimetric defect, in comparison to the results in quadrants of healthy subjects. This confirms the sensitivity of the procedure. QmfrVEP responses can be measured reliably. This pilot study suggests that high SNR values exclude visual field defects and that focal defects can be identified in glaucoma patients. www. gov . NCT00494923.