Hyaluronic acid (“gel shots”)

Hyaluronic acid aims to restore lubrication. In Singapore I commonly use hylan G F 20 (Synvisc®/Synvisc One®) and sorbitol stabilised HA (Synolis™ VA), delivered via a single, carefully placed intra articular injection. Some patients feel a steady improvement over two to six weeks with relief that can extend towards six months. The evidence is mixed. A large meta analysis found small average pain benefits over placebo and flagged a higher rate of serious adverse events in pooled analyses, which is why many guidelines are cautious about routine HA. Yet individual responses vary and certain preparations remain widely used; in clinic I make space for that nuance and decide case by case.

Platelet rich plasma (PRP)

PRP is your own concentrated platelets, prepared the same day, aiming to deliver a pulse of growth factors into the joint. On average, published comparisons increasingly show PRP outperforming hyaluronic acid and corticosteroid for pain and function at three to twelve months, especially when leukocyte poor PRP and multi injection protocols are used. At the same time, one of the largest sham controlled trials reported no advantage of PRP over saline at twelve months, a reminder that technique, preparation and patient selection matter. My practice response to this split evidence is straightforward: I do not mix PRP with steroid in the same treatment cycle because preclinical and translational work suggests steroid can blunt the cellular signalling we are trying to harness. I standardise the PRP preparation and match the protocol to your goals and OA grade. In responders, improvements usually emerge over four to eight weeks and can last six to twelve months. In Singapore, PRP may be self funded or claimed under your hospital insurance with MediSave, depending on the care setting and your policy; we confirm this before booking.

PRP plus hyaluronic acid

There is a combination strategy—PRP plus hyaluronic acid—for selected knees. Recent evidence, including network meta analysis and newer randomised data, suggests the combination can equal or even outperform PRP alone for symptom relief in knee osteoarthritis, although results vary by product and protocol. I reserve this approach for patients whose goals and imaging profile suggest they would benefit from both a lubrication and a biologic signal in the same cycle.

Bone marrow aspirate concentrate (BMAC)

BMAC is a regenerative option that we discuss candidly. A landmark placebo controlled trial found no superiority over saline through six months, and technology overviews from orthopaedic groups describe a still uncertain evidence base. BMAC may have a role in carefully selected patients prepared for close follow up, but I present it as emerging rather than established. In Singapore, it may be self funded or claimed under hospital insurance with MediSave depending on how the procedure is billed and your individual policy; we check your eligibility in advance.

How I perform the procedure

Procedural details matter for both comfort and safety. I use a sterile, day surgery level setup in Singapore, with chlorhexidine or iodine skin prep and draping. The approach is typically an anterolateral, landmark guided injection. Landmark technique keeps costs down and is highly accurate in routine knees. When anatomy is altered by prior surgery, when there is a large effusion to aspirate first, or when precision into the suprapatellar pouch will clearly add value, I use ultrasound guidance. Evidence shows ultrasound improves needle placement accuracy and, in some contexts, patient reported outcomes. I numb the skin and joint lining with a small amount of local anaesthetic, aspirate if the joint is tight, and then make a single, smooth pass into the joint. Afterward you can walk out; most people return to everyday activity straight away and to sport in about a week if comfortable.

What to expect after an injection

Timelines vary by modality. Steroid acts fastest, often within days. Hyaluronic acid usually builds over two to six weeks. PRP tends to declare itself between four and eight weeks. BMAC—when used—generally takes longer. In my cohort of appropriately selected patients, roughly four out of five report meaningful improvement in pain and function by six to twelve weeks, and many enjoy a six to nine month easier movement window before we reassess. These numbers are averages; your knee and your goals are unique.

Safety and how we minimise risks

Safety is excellent when we are disciplined about sterile technique and selection. The most common issue is short lived soreness or a post injection inflammatory flare that settles with ice, rest and simple analgesics. Vasovagal fainting is uncommon and we prevent it with calm pacing, positioning and hydration. True joint infection is rare but is the complication we treat with the greatest respect, hence the scrub, the drape and the no shortcuts culture. For people with diabetes, corticosteroid can trigger a transient rise in blood glucose for two to three days; we discuss that risk beforehand and monitor. I avoid injections in the presence of active skin or joint infection, poorly controlled diabetes or compromised skin at the injection site, and I proceed cautiously and personally when patients are on anticoagulants.

Timing around knee replacement surgery

If you are considering a total knee replacement, we plan injections with an eye to infection risk. Several analyses suggest that intra articular injections close to arthroplasty—particularly within about three months—are associated with a higher risk of postoperative infection, and newer data specifically implicate hyaluronic acid administered within the two months before surgery. Because the signal looks time dependent and patient specific, my standard advice in Singapore is to avoid injections within three months of planned arthroplasty and to coordinate with your surgeon.