ACL Reconstruction Rehabilitation: a Week-by-Week Recovery Timeline

Anterior cruciate ligament (ACL) reconstruction is a treatment in which the rehabilitation that follows is just as decisive as the surgery itself. The new ligament (graft) is weak in the first few months; its vascularization and maturation take up to 12 months. For this reason, recovery is managed by reaching specific milestones (criterion-based progression) rather than by a fixed calendar. The timeframes below are an average framework; graft type, any accompanying meniscus or cartilage procedures, and individual healing rate can change the plan.

Before Surgery: Prehabilitation

Entering surgery with swelling resolved, the ability to fully straighten the knee, and the ability to contract the thigh muscle significantly improves postoperative outcomes. The first 2–4 weeks after the tear should be devoted to this preparation.

Phase 1: Weeks 0–2 — Protection and Activation

• Goals: control swelling, achieve full knee extension (0°), activate the quadriceps, and maintain a normal walking pattern

• Ice and elevation several times a day

• Quadriceps isometric sets, straight-leg raises, heel slides

• Weight-bearing with crutches as tolerated; weight-bearing may be restricted if a meniscus repair was performed

• Passive knee flexion target: roughly 90° by the end of week 2

The most common mistake is focusing on bending the knee while neglecting extension. Failing to regain full extension in the early weeks can lead to a permanent restriction.

Phase 2: Weeks 2–6 — Motion and Control

• Discontinuing crutches, usually week 2–3, once walking without a limp

• Knee flexion target: 120–130° by the end of week 6

• Stationary bike, first for range of motion, then against resistance

• Closed-kinetic-chain exercises: mini-squats, leg press (0–60°), step exercises

• Balance board and single-leg stance work

Phase 3: Weeks 6–12 — Strengthening

• Full range of motion

• Gradual increase in resistance: leg press, lunges, hip and calf strengthening

• Open-kinetic-chain quadriceps exercises (leg extension) may be introduced in a limited, controlled range; current evidence shows the 90–45° range is safe

• Elliptical training, swimming (excluding breaststroke kick)

Phase 4: Months 3–6 — Running and Dynamic Loading

The passage of time alone is not enough to begin running. Criteria required:

• No swelling or pain

• Quadriceps strength reaching at least 70–80% of the uninjured leg

• No inward drift of the knee during a single-leg squat

Once these criteria are met, light running on flat ground is introduced, typically at month 3–4, followed by change-of-direction and jumping drills.

Phase 5: Months 6–12 — Return to Sport

Studies show that returning to contact or pivoting sports before 9 months significantly increases the risk of re-tear; each additional month of delay up to month 9 reduces that risk. The decision to return to sport is based on a test battery:

• Quadriceps and hamstring strength: at least 90% of the uninjured side

• Single-leg hop tests: at least 90% of the uninjured side

• Assessment of movement quality (landing mechanics)

• Psychological readiness: confidence in the knee

Frequently Asked Questions

Should I wear a brace? A locked brace is preferred by some surgeons in the first weeks after surgery; there is no strong evidence that a functional brace prevents re-tear in the long term.

When can I return to work? Desk work is generally possible after 1–2 weeks, jobs requiring standing after 4–6 weeks, and heavy physical work after 3–4 months.

What about driving? For right-knee surgery, reflex braking time typically returns to normal within 4–6 weeks; driving can be resumed once crutches are discontinued and pain-free control is achieved.

What is the risk of re-tear? In young athletes, the risk of re-injury to the same or opposite knee can reach around 20% within 5 years. The most important factors in reducing this risk are completing rehabilitation, meeting return-to-sport criteria, and continuing protective neuromuscular exercises.

This article is for general information purposes; a personal examination is required for an individual treatment plan.