Evaluation of distal femoral cartilage by B-mode ultrasonography and shear wave elastography in patients with knee osteoarthritis: a preliminary study

What is New in Osteoarthritis Imaging?

Osteoarthritis (OA) is the leading joint disorder globally, affecting a significant proportion of the population. Recent studies have changed our understanding of OA, viewing it as a complex pathology of the whole joint with a multifaceted etiology, encompassing genetic, biological, and biomechanical elements. This review highlights the role of imaging in diagnosing and monitoring OA. Today's role of radiography is discussed, while also elaborating on the advances in computed tomography and magnetic resonance imaging, discussing semiquantitative methods, quantitative morphologic and compositional techniques, and giving an outlook on the potential role of artificial intelligence in OA research.

Research progress of ultrasound in accurate evaluation of cartilage injury in osteoarthritis

Osteoarthritis (OA) is a prevalent cause of joint algesia, loss of function, and disability in adults, with cartilage injury being its core pathological manifestation. Since cartilage damage is non-renewable, the treatment outcome in the middle and late stages of OA is unsatisfactory, which can be minimized by changing lifestyle and other treatment modalities if diagnosed and managed in the early stages, indicating the importance of early diagnosis and monitoring of cartilage injury. Ultrasound technology has been used for timely diagnosis and even cartilage injury treatment, which is convenient and safe for the patient owing to no radiation exposure. Studies have demonstrated the effectiveness of ultrasound and its various quantitative ultrasound parameters, like ultrasound roughness index (URI), reflection coefficient (R), apparent integrated backscatter (AIB), thickness, and ultrasound elastography, in the early and accurate assessment of OA cartilage pathological changes, including surface and internal tissue, hardness, and thickness. Although many challenges are faced in the clinical application of this technology in diagnosis, ultrasound and ultrasound-assisted techniques offer a lot of promise for detecting early cartilage damage in OA. In this review, we have discussed the evaluation of ultrasonic cartilage quantitative parameters for early pathological cartilage changes.

The ultrasound assessment of osteoarthritis: the current status

Traditionally, osteoarthritis (OA) is diagnosed with the clinical examination supplemented by the conventional radiography (CR). In the research literature, the role of ultrasound (US) imaging in the diagnostics of OA has risen steadily during the last two decades. US imaging is cheap and globally widely available often already in primary healthcare. Here, we reviewed the most essential US literature focusing on OA diagnostics and progression prediction using the various search engines. Starting from the year 2000, our search provided 1 445 journal articles. After reviewing the abstracts, 89 articles were finally included. Most of the reviewed articles focused on the imaging of knee and hand OA, whereas only a minority dealt with the imaging of hip, ankle, midfoot, acromioclavicular, and temporomandibular joints. Overall, during the last 20 years, the use of US imaging for OA assessment has increased in the scientific literature. In knee and hand joints, US imaging has been reported to be a promising tool to evaluate OA changes. Furthermore, the reproducibility of US as well as its association to MRI findings are excellent. Importantly, US seems to even outperform CR in certain aspects, such as detection of osteophytes, joint inflammation, meniscus protrusion, and localized cartilage damage (especially at the medial femoral condyle and sulcus area). Based on the reviewed literature, US can be truly considered as a complementary tool to CR in the clinical setup for OA diagnostics. New technical developments may even enhance the diagnostic value of the US in the future.

Shear wave elastography and T2* mapping in the detection of early-stage trochlear cartilage damage

BACKGROUND

The presence of degenerative changes in joint cartilage is one of the major features in osteoarthritis.

PURPOSE

To investigate the contribution of shear wave elastography and T2* mapping to the early diagnosis of femoral trochlear cartilage damage.

MATERIAL AND METHODS

A total of 30 individuals whose trochlear cartilage structure was evaluated as normal in conventional magnetic resonance imaging (MRI) sequences (control group) were prospectively compared with 30 patients who had early-stage cartilage damage findings on conventional MRI (study group), by performing B-mode ultrasonography, shear wave elastography, and T2* mapping. Cartilage thickness, shear wave, and T2* mapping measurements were recorded.

RESULTS

After evaluating B-mode ultrasound and conventional MRI sequences, cartilage thickness was found to be significantly higher in the study group on both B-mode ultrasound and MRI. Shear wave velocity values of the study group (medial condyle [MC] 4.65 ± 1.11 m/sn, intercondylar [IC] 4.74 ± 1.20 m/sn, and lateral condyle [LC] 5.42 ± 1.48 m/sn) were observed to be significantly lower than the control group (MC 5.60 ± 0.77 m/sn, IC 5.85 ± 0.96 m/sn, and LC 5.63 ± 1.05 m/sn) (P < 0.05). T2* mapping values were significantly higher in the study group (MC 32.38 ± 4.04 ms, IC 35.78 ± 4.85 ms, and LC 34.04 ± 3.40 ms) than that of the control group (MC 28.07 ± 3.29 ms, IC 30.63 ± 3.45 ms, and LC 29.02 ± 3.24 ms).

CONCLUSION

Shear wave elastography and T2* mapping are reliable methods for evaluating early-stage trochlear cartilage damage.

Osteoarthritis year in review 2022: imaging

PURPOSE

This narrative review summarizes original research focusing on imaging in osteoarthritis (OA) published between April 1st 2021 and March 31st 2022. We only considered English publications that were in vivo human studies.

METHODS

The PubMed, Medline, Embase, Scopus, and ISI Web of Science databases were searched for "Osteoarthritis/OA" studies based on the search terms: "Radiography", "Ultrasound/US", "Computed Tomography/CT", "DXA", "Magnetic Resonance Imaging/MRI", "Artificial Intelligence/AI", and "Deep Learning". This review highlights the anatomical focus of research on the structures within the tibiofemoral, patellofemoral, hip, and hand joints. There is also a noted focus on artificial intelligence applications in OA imaging.

RESULTS

Over the last decade, the increasing trend of using open-access large databases has reached a plateau (from 17 to 37). Compositional MRI has had the most prominent use in OA imaging and its biomarkers have been used in the detection of preclinical OA and prediction of OA outcomes. Most noteworthy, there has been an accelerated rate of publications on the implications of artificial intelligence, used in developing prediction models and performing trabecular texture analysis, in OA imaging (from 17 to 154).

CONCLUSIONS

While imaging has maintained its key role in OA research, publication trends have shown an emphasis on the integration of AI. During the past year, MRI has maintained the highest prevalence in usage while US and CT remain as readily available modalities. Finally, there has been a notable uptake in the development and validation of AI techniques used to perform texture analysis and predict OA progression.

Femoral Cartilage Thickness in Knee Osteoarthritis Patients and Healthy Adults: An Ultrasound Measurement Comparison

Background

Currently, conventional radiography is still widely used to diagnose knee osteoarthritis and assess the grade according to Kallgren and Lawrence's criteria. Ultrasound is a simple, inexpensive, noninvasive, and dynamic modality for evaluating femoral cartilage (FC) thickness. This study aims to measure the FC thickness in knee osteoarthritis (OA) patients and compare it to healthy adults using ultrasound assessment.

Methods

An observational study with a cross-sectional design was conducted at the Department of Physical Medicine and Rehabilitation of Hajj General Hospital, Surabaya, Indonesia, from May to July 2022. Participants radiologically diagnosed with OA were included in the study and assigned to the OA group. Meanwhile, healthy adults without knee symptoms were included in the control group. FC thickness was measured using ultrasound scans at three sites: medial condyle (MC), intercondylar (IC), and lateral condyle (LC) on both sides of the knee.

Results

The mean age in the OA and control groups was 61.03 ± 8.6 and 33.93 ± 14.7 years, respectively. Most participants in both groups were female. The OA group exhibited a thinner FC (1.49-1.63 mm) than the control group (1.68-1.87 mm). There was a significant difference in the mean of the right and left MC in both groups (p < 0.05) but no significant difference in the IC and LC.

Conclusion

OA patients exhibited a thinner FC than healthy adults in the control group. There was a significant difference in the mean thickness of the MC between groups.

Latest advancements in imaging techniques in OA

The osteoarthritis (OA) research community has been advocating a shift from radiography-based screening criteria and outcome measures in OA clinical trials to a magnetic resonance imaging (MRI)-based definition of eligibility and endpoint. For conventional morphological MRI, various semiquantitative evaluation tools are available. We have lately witnessed a remarkable technological advance in MRI techniques, including compositional/physiologic imaging and automated quantitative analyses of articular and periarticular structures. More recently, additional technologies were introduced, including positron emission tomography (PET)-MRI, weight-bearing computed tomography (CT), photon-counting spectral CT, shear wave elastography, contrast-enhanced ultrasound, multiscale X-ray phase contrast imaging, and spectroscopic photoacoustic imaging of cartilage. On top of these, we now live in an era in which artificial intelligence is increasingly utilized in medicine. Osteoarthritis imaging is no exception. Successful implementation of artificial intelligence (AI) will hopefully improve the workflow of radiologists, as well as the level of precision and reproducibility in the interpretation of images.

Application of an indentation sensor for the arthroscopic measurement of articular cartilage stiffness

Direct measurement of cartilage stiffness provides useful clinical information and enables us to develop treatment strategies for patients. We applied an indentation sensor to evaluate cartilage stiffness under arthroscopic control. The purpose of this study was to validate the arthroscopic indentation sensor using cadaver knees and to measure cartilage stiffness in clinical cases. The stiffness of a material with known properties was measured at thicknesses from 2 mm to 10 mm with a 2-mm interval. This was repeated three times at each thickness to evaluate repeatability. The articular cartilage stiffness of the medial and lateral femoral condyles of five human cadaveric knees was measured. The sensor was inclined from 0° to 20° with 1° intervals. The stiffness value at each degree of inclination was compared to evaluate the acceptable measuring angle. Additionally, articular cartilage stiffness was measured in 23 adolescent and 11 adult patients under arthroscopy. Young's moduli of the material were 1.15-1.24 (mean 1.20) MPa. Inter-class correlation coefficients in repeated measurements using the material were 0.83-0.99. There were no differences in the cartilage stiffness between the medial and lateral femoral condyles of the cadaver knees. All condyles showed a nonlinear relationship between force and displacement. The force decreased in all condyles when the tip of the sensor system was tilted. The range of error was < 97.1% within 5° inclination. There was a moderate negative correlation between age and cartilage stiffness in adolescent patients, and a moderate positive correlation in adult patients. Since the sensor system is manually held during measurement, the validity and repeatability to assess material properties of the cartilage may be inaccurate. This study has proven that the instrument can measure the stiffness of joint cartilage reliably and is a useful clinical tool under arthroscopic control.