Rehab
A criteria-based ACL rehab protocol
Five phases with the entry criteria for each. Not a calendar you follow, a set of gates you pass, which is what the 2017 clinical practice guideline actually recommends.
A protocol built on dates says you start running at week 12. A protocol built on criteria says you start running when the knee is quiet, straight, strong enough and walking normally, which for most people lands around week 12. The difference shows up in the people for whom it does not land at week 12, and there are a lot of them.
The 2017 revision of the knee ligament sprain clinical practice guideline from the Academy of Orthopaedic Physical Therapy recommends criterion-based progression rather than time-based progression, along with early weight bearing, immediate knee motion, cryotherapy, supervised rehabilitation combined with a home program, and neuromuscular re-education. The phases below follow that logic. They are not a substitute for the plan your own physical therapist builds, and where the two differ, theirs wins: they have seen your knee.
Phase 1: protect and activate, roughly weeks 0 to 2
- Goal
- A knee that straightens fully, drains, and has a quadriceps that turns on.
- Work
- Quad sets, straight leg raises, heel slides, ankle pumps, patellar mobilization, prone hangs or low-load long-duration extension, cryotherapy and compression, gait training toward no crutches.
- Exit criteria
- Extension equal to the other side, flexion around 90 degrees or more, effusion trace or less, straight leg raise with no extension lag, normal gait without crutches.
Phase 2: strength foundation, roughly weeks 2 to 12
- Goal
- Get the leg back under you and start measuring.
- Work
- Leg press, squats within a permitted range, step-ups and step-downs, hamstring and hip work, calf work, open-chain quadriceps work in the range your surgeon allows, bike and elliptical volume, balance and proprioception.
- Exit criteria
- Full range of motion, no effusion after sessions, single-leg squat and step-down with controlled knee alignment, quadriceps strength commonly around 80% of the other side measured on a dynamometer.
Phase 3: running and impact, roughly months 3 to 5
- Goal
- Reintroduce impact without reintroducing swelling.
- Work
- Graded running progression starting with intervals, double-leg jumping and landing then single-leg, straight-line agility, continued heavy strength work, hamstring emphasis if you had a hamstring autograft.
- Exit criteria
- A running volume tolerated with no next-day effusion or pain, landing mechanics without visible collapse or favoring, quadriceps strength climbing toward 90%.
Phase 4: change of direction and sport specifics, roughly months 5 to 8
- Goal
- Turn a strong straight-line leg into a leg that cuts.
- Work
- Planned change of direction before reactive, deceleration work, sport-specific drills, position-specific conditioning, controlled contact where the sport has it, and the first full run of the testing battery so you know the gaps early.
- Exit criteria
- Full participation in non-contact practice, hop test symmetry approaching 90%, no effusion, and an ACL-RSI score you have actually recorded.
Phase 5: return to sport and beyond, month 9 onward
- Goal
- Return, then keep building for a second year, because the risk window is open.
- Work
- Graded return to competition, maintained strength training, continued plyometric and neuromuscular work, periodic retesting.
- Exit criteria
- There is no exit. Graft ruptures in one series occurred at an average of 1.8 years after surgery, with 74% inside two years, and athletes who returned with quadriceps asymmetry still unloaded the operated leg two years later.
The criteria that gate every phase
Effusion, extension, measured strength, and quality of single-leg movement. Four things. If any of them is off, the answer is almost never to add a new exercise. It is to fix that one.
Modifiers that change the plan
- Meniscus repair. Adds weight-bearing and flexion restrictions for weeks, set by the surgeon. This is the most common reason a real protocol looks slower than the one you read online.
- Hamstring autograft. Slower hamstring strength recovery, and hamstring to quadriceps ratio matters: in the Kyritsis cohort a lower ratio at 60 degrees per second was associated with a hazard ratio of 10.6 per 10% difference.
- Patellar tendon autograft. More anterior knee pain and kneeling trouble, so quad loading progressions get managed around symptoms.
- Cartilage procedure. Its own restrictions, usually the most conservative of all.
- Age under 20. Not slower rehab, but a much longer runway before return, because the risk numbers are far worse in this group.