Why rehabilitation is part of the treatment
Whatever the cell or platelet product does, it does it in a joint that has to be loaded correctly: enough motion to nourish cartilage and remodel tissue, not so much that the early inflammatory phase is overwhelmed. Trials of PRP and MSC injection that included structured rehabilitation reported better functional outcomes than injection alone. A clinic that injects and sends you to the airport the next day with "take it easy" has done half the job.
Phase 1: days 0 to 3 (protection)
- Expect increased pain and swelling for 24 to 72 hours; this is the intended inflammatory response, not a complication
- Ice 15 minutes several times a day; acetaminophen for pain; no NSAIDs (see medications to stop)
- Walk short distances with normal gait; crutches only if the clinic prescribes them
- Gentle range of motion: heel slides, ankle pumps, quad sets
- No flights of more than a couple of hours until day 2 to 3; keep the knee moving on the plane; see flying and activity limits
Phase 2: days 4 to 14 (early loading)
- Daily walking, building toward 20 to 30 minutes on flat ground
- Stationary bike with no resistance, 10 to 20 minutes, once swelling allows
- Closed-chain strengthening: mini squats to 45 degrees, step-ups to a low step, wall sits
- Avoid impact, kneeling, deep squats, and pivoting
- Pool walking is excellent once the injection site is fully healed (about a week)
Phase 3: weeks 3 to 6 (progressive strengthening)
- Add resistance on the bike; progress squats and lunges within pain-free range
- Hip and glute strengthening, which offloads the knee
- Elliptical and rowing acceptable; still no running or jumping
- Formal physical therapy twice a week if available; a home program otherwise
Phase 4: weeks 7 to 12 (return to activity)
- Gradual return to jogging on soft surfaces from about week 8 if pain-free and no swelling
- Sport-specific drills from week 10 to 12
- Full return to sport typically 3 months, longer for contact or cutting sports
| Week | Allowed | Not yet |
|---|---|---|
| 0-2 | Walking, gentle ROM, no-resistance bike | Impact, kneeling, deep squat, long flights day 0-1 |
| 3-6 | Resistance training, elliptical, pool | Running, jumping, pivoting |
| 7-12 | Progressive jogging, sport drills | Contact sport before 12 weeks |
Call the clinic if
- Pain or swelling worsens after day 3 instead of easing
- Fever, redness spreading from the injection site, or the joint feels hot
- The knee locks or gives way
- Calf pain or swelling (possible clot, especially after a long flight)
When to judge the result
Not at week 2. Symptom improvement from orthobiologics typically emerges between weeks 6 and 12 and can continue to 6 months. Keep a simple weekly pain and function log so you and the clinic can assess the trajectory honestly; see maximizing results and results timelines.
Regulatory status: FDA vs INVIMA
United States (FDA): No stem cell product is FDA-approved for orthopedic, neurologic, or systemic use. Minimally manipulated same-day autologous procedures are marketed under a narrow exemption; culture-expanded cells and most umbilical products are unapproved biologics and the FDA's authority over them was reaffirmed in federal court in 2024. Florida's 2025 law permits certain treatments under state rules but does not create FDA approval.
Colombia (INVIMA): Cell therapies are regulated as advanced-therapy products. Clinics require INVIMA habilitation for the facility and, for laboratory-processed products, product-level authorization or an approved research protocol. Ask to see the INVIMA registration number and verify the treating physician on ReTHUS. "INVIMA registered" for the clinic is not the same as an authorized product.
Frequently asked questions
How soon can I walk after a knee stem cell injection?
Same day, with normal gait for short distances. Build walking time over the first two weeks.
When can I run again?
Usually from about week 8, if pain-free and not swollen, progressing to full sport around 12 weeks.
Do I need physical therapy after PRP or stem cells?
Strongly recommended. Structured rehabilitation is associated with better functional outcomes in trials.
Want a clinic that hands you a real rehab plan?
We ask for the written post-injection protocol before referring. Tell us your knee situation and we will send clinics that have one.
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