What Is ‘Liquid Prosthesis’ (Hydrogel) Treatment for Knee Osteoarthritis? Is It a Non-Surgical Solution

Knee pain is one of the leading health problems that significantly reduces quality of life, especially after a certain age. In the process known as knee osteoarthritis, commonly referred to as "wear and tear" arthritis, the cartilage gradually deteriorates, the natural lubricating fluid inside the knee decreases, and the bones begin to rub against each other. In recent years, one of the most promising treatment methods developed to slow down or interrupt this process has been "Liquid Prosthesis" (Hydrogel) injections. But does this treatment really work? Who is it suitable for? Here are the answers based on current scientific evidence.

Question: What exactly is a liquid prosthesis (hydrogel)? Is plastic being injected into the knee?

No, plastic is not being injected into your knee. A liquid prosthesis is a biocompatible (body-friendly) gel structure composed largely of water, most commonly containing polyacrylamide-based materials. Its most important feature is that it is not rapidly absorbed by the body and can remain inside the joint for a very long time. Similar to adding lubricant to an aging machine, it physically restores the knee's lost lubrication and shock-absorbing function.

Question: How is this different from traditional "rooster comb" injections (Hyaluronic Acid)?

Hyaluronic acid injections, which have been used for years in knee osteoarthritis treatment, usually remain in the knee joint for about 6 months to 1 year before being completely broken down and absorbed by the body. Therefore, their effects are temporary. According to recent clinical studies, liquid prosthesis (hydrogel) injections create a long-lasting layer inside the joint and are not easily degraded by the body. Long-term scientific follow-up studies suggest that these gels may reduce pain and improve mobility for up to 3 years.

Question: Can a liquid prosthesis replace surgery? Can it prevent a real knee replacement operation?

Liquid prosthesis treatment is a powerful bridge option for patients who are not yet at the stage of surgery or who wish to delay surgery. In advanced osteoarthritis cases where bone is completely rubbing against bone and the knee alignment is significantly disrupted, the definitive solution is still surgical (metal) knee replacement. However, in patients with early to moderate osteoarthritis whose daily activities are limited by pain, liquid prosthesis treatment may significantly delay the need for knee replacement surgery by reducing cartilage friction.

Question: What is the treatment process like? Is hospitalization necessary?

It is a very practical and comfortable procedure. Hospitalization is not required. The injection is typically performed as a single-session procedure under sterile conditions in an operating room or clinical setting. The procedure usually takes about 10–15 minutes. Patients can walk out and return home or even to work immediately afterward.

Question: Are there any side effects of liquid prosthesis treatment?

Since the material is biocompatible, the risk of rejection or allergic reaction is extremely low. During the first few days after the injection, patients may experience a mild feeling of fullness or temporary soreness in the knee, which is considered normal. As with all intra-articular injections, the most important potential risk is infection. Therefore, it is essential that the procedure be performed under fully sterile conditions by an experienced orthopedic specialist.