Osteoarthritis (OA) is a serious worldwide public health concern, causing increased
disability-adjusted life years (DALY), the reasons of which include rising prevalence of
obesity and increasing older populations. The knee is one of the most easily injured
joint in the body, and knee OA can become a chronic and disabling condition that pose a
threat to not only the patient but also his or her caretakers and healthcare resources.
The prevalence of knee OA is 5% - 15% in men over 60 years, and 10% - 25% in women aged
more than 60.
Knee OA can result from injuries, diseases, or wear and tear from overuse. It refers to
structural changes that affect subchondral bone, articular cartilage, menisci, ligaments,
synovium, and other joint structures. Currently, there are several conservative
management of knee OA, including physiotherapy (therapeutic exercise, diathermy,
electrotherapy), oral or topical medications, intra-articular and extra-articular
injections, and radiofrequency.
There are various substances used in injections for knee OA, among which are
corticosteroid, platelet-rich plasma (PRP), AmnioFix, exosome, dextrose, and hyaluronic
acid (HA). Compared with PRP, AmnioFix, exosome, and HA, which are not covered by the
health insurance system, dextrose is a readily available and cost-effective substance.
The principle of hypertonic dextrose injection, "prolotherapy", is injection of small
volumes of the irritant solution at or around the lesion in order to stimulate fibroblast
and vascular proliferation, local tissue healing, reduction of joint instability, thus
resulting in pain relief. Previous studies have demonstrated that prolotherapy resulted
in clinically meaningful sustained improvement of function and pain in knee OA, and there
were no severe adverse events related to hypertonic dextrose injection. A study in 2023
showed that among various dextrose concentrations, higher concentrations demonstrated
greater improvement of knee OA, thus 20% dextrose is recommended.
Regarding the site of dextrose injection in knee OA, previous studies demonstrated
comparable effects of intra-articular and extra-articular injections. The periarticular
injections include points around the knee where periarticular nerves exit the joint
capsule, and acupuncture points at upper medial and lateral parts of knee joint. A study
in 2024 revealed that prolotherapy combining intra-articular with peri-articular
perineural injection resulted in better pain alleviation and improvement in knee joint
function in knee OA. There are several choices of imaging modality for recognizing the
sites of lesion in knee OA, such as X-ray, ultrasound (US), and magnetic resonance
imaging (MRI). Radiography is used to assess osteophytes, joint space narrowing, and
subchondral sclerosis, but it has limited ability to detect synovial inflammation, joint
effusion, soft tissue abnormalities, and early cartilage damage. US can be used to
evaluate synovial fluid and cartilage thickness, but not deep structures (e.g.
subchondral bone change, meniscus tear, and ACL tear, etc.). On the other hand, MRI is an
optimal and accurate imaging choice for visualizing soft tissue as well as deep
structures (e.g. ACL, meniscus, etc) in knee OA. The MRI findings of knee OA includes
cartilage damage, meniscus tear, bone marrow lesions, synovitis, ligamentous laxity, and
osteophytes. The detection of bony lesions can aid intraosseous Infiltrations, and signs
of ligamentous laxity also provides target for ligaments injection. However, there is no
current evidence on the effectiveness of prolotherapy targeting knee OA lesion sites
according to MRI findings.
Because the effectiveness of prolotherapy targeting lesion sites according to MRI
findings has not been well established, the investigators aim to investigate whether
injecting dextrose into MRI-positive lesion sites is more beneficial for knee OA
comparing to intra-articular injections. The investigators hypothesize that MRI could be
a good choice for the guidance of prolotherapy targets.