Recovery from knee cartilage repair is SLOOOOOOOOOOOOOOW.
Most people spend about 6 to 8 weeks on crutches with little or no weight on the leg, and return to pivoting sport takes anywhere from about 4 months to 18 months, depending on which repair you had.
New cartilage, or a transplanted plug, has to settle and firm up before it can take load, and it does that over months, not weeks. Too much load too early can damage the repair.
Protocols differ between surgeons and depend on where the damage was and what else was done. Your surgeon’s protocol comes first. Use theirs.
Which repair did you have?
- Microfracture: keyhole surgery where small holes are made in the bone under the damaged patch. Blood and marrow cells fill the gap and form a tougher, scar-like cartilage. Used for smaller patches. It’s the quickest to recover from, but the new tissue may not last as well as other repairs
- Osteochondral autograft: plugs of healthy cartilage and bone are moved from a less loaded part of your own knee into the damaged area. The plug brings real cartilage with it, and bone heals to bone
- Osteochondral allograft: the same idea, using donor tissue, for larger defects. Usually open surgery, and the donor bone takes longer to knit
- Cell-based repair (autologous chondrocyte implantation): two operations. First, a small sample of your cartilage is taken and the cells are grown in a lab for about a month. Then the cells are put back into the defect. The repair matures slowly, which is why this has the longest rehab
The American Academy of Orthopaedic Surgeons explains each type of cartilage restoration in more detail.
If your leg is bowed and the damage is on the inner side, the surgeon may also realign the bone to take load off the repair. See high tibial osteotomy.
The crutches phase
- After microfracture: crutches with just a light touch of the foot, or no weight at all, for about 6 to 8 weeks
- After an autograft plug: often no weight for the first couple of weeks, then building up, with full weight by around 6 to 8 weeks
- After a donor graft: often no weight for 6 to 8 weeks, with full weight by around 8 to 12 weeks
- After cell-based repair: limited weight on crutches for up to about 3 months, built up in stages
- If the repair was on the kneecap or its groove: the rules often flip. You may be allowed to walk on the leg sooner, but in a brace that stops the knee bending, for around 6 weeks or more
“Touch weight” and “partial weight” mean different things. See weight bearing after surgery if you’re unsure which one you’ve been given.
The bending machine (CPM)
- What it is: a continuous passive motion machine slowly bends and straightens your knee while you lie still
- Why it’s used here: gentle movement helps the new cartilage form and stops the knee stiffening while you can’t walk on it
- How long: after microfracture, some surgeons ask for 6 to 8 hours a day for about 6 weeks. You can usually split it into several sessions
- Not every surgeon uses it. If you don’t get a machine, you’ll usually be given bending exercises to do often through the day instead
Move the knee early. Load it late.
Month by month
- Weeks 0 to 6: crutches, protected weight, and lots of movement. Get the knee fully straight, wake up the thigh muscle, and keep swelling down
- Weeks 6 to 12: weight is built up and crutches come away, sooner after plugs and microfracture, later after cell-based repair. Stationary bike, walking practice, and strength work for the thigh and hip
- Months 3 to 6: normal walking, longer bike rides, swimming. Strength keeps building. Jogging may start toward the end of this window after microfracture or a plug, if your surgeon agrees
- Months 6 to 12: running, jumping and change-of-direction drills, easy to hard
- Beyond 12 months: full sport after cell-based repair is often in the 10 to 18 month range
Return to sport
- Microfracture: no pivoting, cutting or jumping for at least 4 to 6 months, and often longer
- Autograft plug: often around 6 to 9 months
- Donor graft: often around 7 to 13 months
- Cell-based repair: often around 10 to 18 months
- How many get back: roughly 3 in 4 people after microfracture and closer to 9 in 10 after a graft return to sport
- What helps your odds: being younger, a smaller defect, a shorter spell of symptoms before surgery, no previous knee operations, and sticking with rehab
Time alone isn’t the test. Most surgeons and physios also want to see strength close to the other leg, no swelling after training, and sport drills done at full speed without pain.
What’s normal
- Swelling after you step up activity. If it settles within a day, it’s usually fine. If it keeps coming back, ease off and mention it
- A thigh muscle that looks thin after weeks on crutches. It comes back with work
- Clicking without pain
- Feeling slow compared with a friend who had a meniscus trim. That’s a much smaller operation with a much faster recovery. See meniscus surgery recovery
Call your surgeon today if
- The wound is red, spreading, hot, weeping or draining, or you have a fever or chills
- Your calf is painful, tender or newly swollen: possible clot in the leg. Weeks on crutches raise the risk
- The knee suddenly swells up, locks or catches, especially after a slip or twist
- Pain is getting WORSE instead of slowly better
Go to the emergency department if
- You are suddenly short of breath or have chest pain. A clot can travel to the lung
Mention it at your next review if
- The knee still won’t go fully straight at around six weeks
- Bending has stalled for a couple of weeks
- Swelling returns every time you increase activity
- You’re unsure how much weight you’re allowed, or when that changes
Protect the repair early, load it slowly, and measure recovery in months.