Ultrasound Imaging in Knee Osteoarthritis: Current Role, Recent Advancements, and Future Perspectives

Abstract

While conventional radiography and MRI have a well-established role in the assessment of patients with knee osteoarthritis, ultrasound is considered a complementary and additional tool. Moreover, the actual usefulness of ultrasound is still a matter of debate in knee osteoarthritis assessment. Despite that, ultrasound offers several advantages and interesting aspects for both current clinical practice and future perspectives. Ultrasound is potentially a helpful tool in the detection of anomalies such as cartilage degradation, osteophytes, and synovitis in cases of knee osteoarthritis. Furthermore, local diagnostic and minimally invasive therapeutic operations pertaining to knee osteoarthritis can be safely guided by real-time ultrasound imaging. We are constantly observing a growing knowledge and awareness among radiologists and other physicians, concerning ultrasound imaging. Ultrasound studies can be extremely useful to track the response to various therapies. For this specific aim, tele-ultrasonography may constitute an easy tool aiding precise and repeated follow-up controls. Moreover, raw radio-frequency data from US backscattering signals contain more information than B-mode imaging. This paves the way for quantitative in-depth analyses of cartilage, bone, and other articular structures. Overall, ultrasound technologies and their rapid evolution have the potential to make a difference at both the research and clinical levels. This narrative review article describes the potential of such technologies and their possible future implications.

Keywords: interventional; knee; narrative review; osteoarthritis; telemedicine; ultrasonography; ultrasound imaging.

Figure 1

MRI (T2w fat saturated coronal sequences) of a patient with suspected knee osteoarthritis at baseline (Panel A) and seven years later (Panel B). A progression of cartilage damage over time can be noted, especially at the medial femur condyle, where a large defect is detectable (arrow, Panel B), even if joint space thickness remains the same.

Figure 2

Ultrasound image (B-mode) longitudinal suprapatellar view showing joint effusion (asterisks) and synovial inflammatory thickening (arrow) within the sub-quadricipital recess.

Figure 3

Ultrasound image (Power-Doppler) longitudinal, lateral suprapatellar view showing synovial inflammatory foci with inflammatory hyperemia (arrow).

Figure 4

Ultrasound image (B-mode) longitudinal posterior view in the medial aspect of the popliteal fossa showing large fluid collection (asterisks) within the medial head of the gastrocnemius and the semimembranosus tendons’ sheet (Baker’s cyst).

Figure 5

An ultrasound image (B-mode) longitudinal view of the medial aspect of the knee shows initial signs of osteoarthritis, with small osteophytes of the femur and tibiae epiphyses (arrows).

Figure 6

Trochlear femur’s cartilage assessed with US through an axial suprapatellar view with a flexion of the knee (light blue, superficial layer of the cartilage—yellow, cortical bone of the trochlear groove): Normal cartilage (Panel A), mild (Panel B), moderate (Panel C), and severe (Panel D) cartilage damage.

Figure 7

Tele-ultrasonography approach. The figure presents a schematic representation of the asynchronous tele-ultrasonography method proposed in recent research [89]. The clinician (left panel) acquires reference standard images for knee evaluation; the subject (right panel) reproduces offline the images of the clinician using specific guidance systems (wearable probe positioner and graphical user interface). Modified from [89].

Figure 8

Ultrasound-guided intra-articular lateral needle (20 Gauge—arrow) approach into a suprapatellar recess distention (blue line) with abundant joint fluid collection (asterisk) in a patient with knee osteoarthritis. Fluid aspiration and corticosteroid injection have been performed under ultrasound guidance.