What happens on the day of your Liquid Cartilage injection

On the day of your appointment, the Liquid Cartilage™ (ChondroFiller™) injection is delivered as an ultrasound-guided outpatient procedure — not surgery. There is no theatre admission, no overnight stay, and no general anaesthetic. The appointment itself takes roughly 30 minutes under local anaesthesia or mild sedation, and patients walk out the same day.

Before you leave, a written aftercare letter is provided covering what to do at home, what is normal, and when to seek advice. It is worth reading this carefully before the local anaesthetic wears off, because that is when the first wave of post-injection soreness typically arrives — usually within 24–48 hours of the procedure.

Some pain, swelling, and stiffness around the hip joint in the first few days is entirely normal and expected. The collagen scaffold has just been placed into the joint, and the surrounding tissue responds accordingly. Paracetamol is recommended for pain relief and ibuprofen for inflammation; taken regularly for the first few days, they are usually sufficient to keep discomfort manageable. Most patients find they are mobile enough for light everyday activity within a few days of the injection, though heavy loading of the hip should be avoided from the outset.

Why the first six weeks are called the Protect phase

The name 'Protect phase' is deliberate. The first 4–6 weeks after a Liquid Cartilage™ injection carry that label in the rehabilitation protocol because the scaffold inside the hip joint is genuinely vulnerable during this window — and the activity rules follow directly from its biology.

Within 3–5 minutes of injection, the collagen solution sets into a stable gel. It bonds almost immediately with the body's natural fibrin, anchoring itself to the cartilage defect. What happens next takes longer: the patient's own progenitor cells — drawn from the surrounding synovium and bone — begin migrating into the scaffold over the days and weeks that follow. This process, known as acellular matrix-induced chondrogenesis, is how the gel supports the body's own repair processes. The collagen provides the structural framework; the body's cells gradually populate it and begin building new tissue.

At this early stage, however, the scaffold is exactly that — a framework. It is not yet mature cartilage, and it does not yet have the mechanical resilience to withstand significant hip joint load. Applying heavy load to the hip too soon risks displacing or degrading the gel before those migrating cells have had time to anchor it in place.

The restriction is not arbitrary caution. It reflects the sequence of events happening inside the joint: gel sets, fibrin binds, cells arrive, tissue matures. Each step depends on the one before it, and the Protect phase is designed to give that sequence the time it needs.

Activity and movement during weeks one to six

Broadly speaking, the Protect phase divides activity into two categories: things the hip can tolerate while the scaffold integrates, and things it cannot.

On the permissible side, short walks around the home, managing stairs at a gentle pace, and routine self-care are generally feasible within a few days of the injection for most patients. The goal is to keep the hip moving — controlled, unhurried movement discourages stiffness without placing the collagen scaffold under load it cannot yet handle.

On the other side of that line sit strenuous or prolonged walking, lifting, impact activity (running, cycling on resistance, sport), and extended periods of standing. These apply consistent force to the hip joint at precisely the point when the scaffold's cellular population is still in its earliest stages, and they should be avoided throughout the full six-week window.

For questions that sit between those two poles — whether crutches are needed, how many stairs are reasonable on a given day, when driving is safe, or when to return to a desk versus a physical job — the answer depends on individual hip function and how the joint responds in the days after the injection. Driving, in particular, is affected both by any sedation used during the procedure and by whether the hip can respond quickly and comfortably in an emergency. These are practical questions worth raising directly with the Lincolnshire Hip clinical team at your follow-up, rather than applying a single fixed rule.

Managing pain and soreness in the first weeks

The practical point on medication that most patients do not hear clearly enough: ibuprofen and other NSAIDs should be taken regularly for up to seven days after the injection to manage inflammation, but not beyond that without clinical review. Because the scaffold is undergoing an active biological process — host cells migrating in and beginning to build new tissue — prolonged anti-inflammatory use in the weeks that follow could, in principle, interfere with that repair activity. Paracetamol remains available for pain relief as needed throughout the Protect phase without that concern.

TENS (transcutaneous electrical nerve stimulation) is noted in the rehabilitation guidance as a non-pharmacological option if the clinician considers it appropriate, and may suit patients who prefer to minimise medication in the early period.

More important than the specific analgesic choices is knowing what does — and does not — warrant contacting the clinical team. Mild soreness that eases gradually over the first few days is the expected trajectory. Pain that worsens significantly after the initial settling period, or that is accompanied by heat, redness, or a fever, falls outside normal post-injection recovery and should prompt a call to Lincolnshire Hip rather than a higher dose of over-the-counter analgesia.

What the Liquid Cartilage scaffold is doing inside the hip joint

The six weeks of the Protect phase cover only the scaffold's stabilisation window. What follows is a repair process that unfolds over months — and understanding that timeline helps patients read their own progress more realistically.

As outlined in the earlier section on why the Protect phase exists, the scaffold works by drawing the patient's own cells into a collagen matrix. Once those cells establish themselves, the cartilage defect gradually fills with new tissue over approximately 12 months. The collagen itself is not permanent: designed to be fully biological, it is resorbed and replaced by the patient's own cartilage-like tissue within one to two years. This distinguishes Liquid Cartilage™ from Arthrosamid, which is a non-regenerative hydrogel that remains in the joint to provide cushioning rather than promoting structural repair, and from hyaluronic acid, which clears from the joint within weeks without contributing to tissue rebuilding.

Patient selection shapes what this timeline means in practice. Liquid Cartilage™ targets focal, isolated Grade III/IV cartilage defects with healthy surrounding borders — not diffuse hip arthritis affecting the joint broadly. Patients whose hip damage is more widespread are likely to be better served by a different pathway, and that is something the Lincolnshire Hip assessment process establishes before any injection is planned.

In published clinical data, hip applications have been associated with around a 30-point improvement in modified Harris Hip Score over 12 months. That figure reflects meaningful functional gain reported in clinical series; it is not a guaranteed individual outcome, and actual results depend on defect characteristics, baseline function, and how consistently the phased recovery plan is followed.

After six weeks: the start of the Strengthen phase

Progress into the Strengthen phase is a clinical decision, not a date on the calendar. Around weeks four to six, the clinical team will assess how the hip has responded and whether it is ready for more. The Strengthen phase itself — which typically runs from weeks six to twelve — introduces progressive loading and physiotherapy aimed at rebuilding the muscle strength and stability the hip joint needs for everyday and active life.

The biological process is still active at that point. Host cells continue maturing within the scaffold, and the cartilage defect fills progressively over roughly 12 months. Feeling noticeably better at week six is a positive signal, but it reflects early gains rather than the conclusion of the repair arc; the most meaningful remodelling continues beneath the surface long after the activity restrictions have lifted.

Follow-up appointments at Lincolnshire Hip's Grantham or Sleaford clinics are where that progression is assessed, the pace of loading is set, and any questions about the recovering hip joint are answered in person — the right moment to have a clinician evaluate the joint rather than rely on symptoms alone. For patients who have not yet had an initial assessment, Lincolnshire Hip is part of the MSK Doctors group and accepts patients without referral.