Knee osteoarthritis and hyaluronic acid injections
In osteoarthritis the cartilage covering the joint surfaces wears down. The joint loses smoothness and begins to hurt — at first under load, later at rest. The synovial fluid changes too: it becomes less viscous and loses part of its lubricating and cushioning effect.
That is where viscosupplementation comes in. Hyaluronic acid is injected directly into the joint to improve lubrication. It does not rebuild cartilage.
Where injections sit among the options
Hyaluronic acid is one option among several, and rarely the first:
- Exercise and strength training — well studied and first in the guidelines. A strong thigh muscle takes load off the joint.
- Weight reduction where there is excess weight; every kilogram counts several times over in the knee.
- Physiotherapy, insoles, braces to unload the joint and improve tracking.
- Pain medication, usually anti-inflammatory, for a limited period.
- Injections into the joint — corticosteroids for acute inflammation, hyaluronic acid to improve lubrication.
- Surgery, up to joint replacement, where symptoms cannot be controlled otherwise.
Why the evidence is debated
Search for hyaluronic acid and the knee and you will quickly find critical assessments. Several health technology bodies rate viscosupplementation unfavourably, on the grounds that the benefit in trials is inconsistent and the difference from a sham injection is often small. You should know that before you decide.
Plainly: three published studies exist for Crespine Gel, and none of them had a control group. They show that the people treated were better afterwards and that this held for twelve months. They cannot show how much of that is due to the product. Anyone telling you otherwise is overreading the data.
Two of the three were funded by the manufacturer or a distribution partner; that is disclosed in the publications. The third, at a university hospital in Karachi, declares no funding — but has only 25 participants.
What Crespine Gel is
Crespine Gel is a gel implant of cross-linked hyaluronic acid made in Germany. It differs from many preparations in being given as a single 2 ml injection per treatment course, rather than a course of three to five weekly appointments.
In the cohort study by Suppan and colleagues (2026) with 111 patients, the improvement in pain and mobility was measurable at three months and held to month twelve. The limitations of that study are in the section above.
The intended purpose covers osteoarthritis of knee or hip. Crespine Gel is not supplied to private individuals; a physician gives the injection.
Common questions
What is viscosupplementation?
Viscosupplementation means injecting hyaluronic acid directly into a joint affected by osteoarthritis. Healthy synovial fluid contains hyaluronic acid and is viscous; in osteoarthritis it thins out and loses some of its lubricating and cushioning effect. The injection aims to improve that. It does not rebuild cartilage.
How long does a gel injection for the knee take to work?
In the cohort study by Suppan and colleagues, the improvement in pain and function was measurable at the first follow-up after three months. When an individual notices a change cannot be derived from that and varies from person to person.
How long does the effect last?
In the same study, the improvements measured at three months were largely unchanged at the end of follow-up after twelve months. The study had no control group, so it cannot show how much of that is attributable to the product.
How many injections are needed?
Crespine Gel is intended as a single injection per treatment course. Many other hyaluronic acid preparations are given as a course of three to five injections a week apart. Whether and when a repeat makes sense is decided by the treating physician.
Which joints can be treated?
The instructions for use cover osteoarthritis of the knee or hip joints. Use in other joints is not covered by the intended purpose.
What are the possible side effects?
The instructions for use list temporary redness, mild swelling, pain and a sensation of heat, usually resolving within two to five days. Hypersensitivity to hyaluronic acid occurs in fewer than 1 % of cases. The studies differ: 1.8 % reported transient pain in Suppan et al., while in Bashaireh et al. 33 of 84 participants — 39 % — had increased pain and limited knee mobility 72 hours after injection, most of them treated with analgesics. All events were local and transient, and no serious complications occurred in any of the studies.
Does the injection replace surgery?
No. Hyaluronic acid injections address symptoms, not restoration of the joint. Whether surgery is necessary or advisable is a separate medical decision.
Next steps
Whether treatment with hyaluronic acid makes sense for you is decided by an orthopaedic examination. This page does not replace a consultation or a diagnosis.
Find out how to obtain it in your country
For physicians: professional area.