AFTER MACINothing on this page is filtered by lesion location — it applies to everyone.

Stop reading and call someone

If any of the things below is happening, this is the only page that matters. Call your surgical team, or emergency services if you can’t reach them. Don’t wait for morning, and don’t wait to feel certain.

Your surgical team

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Emergency services

BLOOD CLOTPOSSIBLE BLOOD CLOT · DVT

Calf pain, tightness, or swelling — usually one leg

One calf, new, warm. Nothing at home rules it out. With chest pain or breathlessness: emergency services, not a phone call.Often warm to touch. Knee surgery is a known risk window for clots, and this cohort has had them. Chest pain or breathlessness alongside it is an emergency, not a phone call.

Not this: the ache of a leg that has been working. But nothing you can do at home rules a clot out — not warmth, not where it hurts, not whether elevating helps. If it is one calf and it is new, make the call.

INFECTIONPOSSIBLE INFECTION

Fever, spreading redness, or wound discharge

Over 101°F or 38.5 °C, leaking after it had stopped, or pain climbing day over day.A temperature over 101°F — or 38.5 °C, the line a joint-replacement guideline draws — a wound that starts leaking after it had stopped, redness expanding beyond the incision, or pain climbing day over day instead of easing. Wound infections happened in this operation's published cohorts.

Not this: the ooze and bruising of a healing wound. What matters is the direction of travel: leaking that had stopped and restarted, redness that is spreading, pain that is climbing.

GRAFT PROBLEMPOSSIBLE GRAFT PROBLEM

The knee locks, catches, or gives way

A hard block, or range it had yesterday and refuses today.A hard block to movement, a loud catch with a sharp pain, or the joint suddenly refusing the range it had yesterday. A knee that will not move is a surgical question, and they would rather see it early.

Not this: the stiffness of a joint that has been still. A knee that is merely tight will still move; call about one that will not, or one that has lost range it used to have.

FAST SWELLINGSWELLING THAT ARRIVES FAST

The knee fills quickly, or keeps filling

Filling over hours, not days, or fuller each time you look. Say how fast it came on.A joint that swells over hours rather than days, or that is visibly fuller each time you look. Tight, warm, hard to bend — and different in kind from the puffiness that follows a hard session and settles by morning. Report how fast it came on, because the speed is the part that matters.

Not this: the familiar swelling that follows a session and is down by the next morning. That one is a dose question and the program already answers it. This is swelling with its own momentum.

LOSING RANGERANGE GOING BACKWARDS

Bend or straightening you had before, slipping away week on week

Range you had, going backwards over weeks. Easier to treat early than late.Not a bad day — a direction. Stiffness that builds after an operation done through an open joint is the complication early movement work exists to prevent, and it is treatable far more easily early than late.

Not this: a stiff morning, or a week set back by a hard session. This is range you had, and no longer have, over weeks.

WOUND OPENINGWOUND OPENING

The incision separates, or will not close

A wound that had closed and has not stayed closed. Same-day call.Edges parting, a gap appearing where the wound had sealed, or anything coming through it. This is a same-day call rather than a wait-and-see.

Not this: a scab, or the ridge of a healing scar. What matters is a wound that had closed and has not stayed closed.

AFTER A FALLSUDDEN CHANGE AFTER A FALL

A fall or twist, then swelling or pain you can't settle

Tell them the mechanism as well as the symptom.Swelling that comes up fast, or being unable to bear weight you could bear before. Report the mechanism as well as the symptom — how it happened changes what they look for.

Not this: a stumble you caught, that settled. A fall the knee does not settle after is worth the call, whatever the clock says.

What to say when you call

Lead with the operation and the date: matrix-assisted chondrocyte implantation, which knee, how many weeks ago. Then the symptom, when it started, and whether anything changed just before it. Whoever picks up may never have heard of this surgery, and that framing saves ten minutes.

If you are reading this at 3am and unsure whether it counts: calling and being told it’s nothing is the correct outcome. Nobody on a surgical team considers that a waste.

Evidence status of this page

General post-operative safety guidance, not MACI-specific research. It is here because it is standard and consequential, not because a trial ranked these symptoms. The temperature comes from patient instructions rather than studies — two clinics that operate on this kind of knee give 101°F, and a physiotherapy guideline for joint replacement gives 38.5 °C. The other warning signs carry no number in this site’s sources. Act on them anyway: this is the one page where being wrong in the cautious direction costs nothing.

Not urgent, still worth asking

Swelling that returns after activity, night pain in the first weeks, clicking without pain, a bend that has stopped improving — these belong in your questions list, not on this page. A bend that has stalled is different from one that is going backwards week on week — that one is above.

Written by a patient, not a clinician. On this page more than any other: your team’s judgement, not ours.