ACL Reconstruction & Rehab:

What Is An ACL Reconstruction?

ACL surgery typically refers to surgical reconstruction of the torn ligament using a graft (commonly from the hamstring, patellar tendon, or quadriceps tendon). In some rare cases, primary ACL repair may be used if the ligament is torn from the bone but otherwise intact. Most cases, however, involve full reconstruction.

Rehabilitation Overview

Rehab begins immediately after surgery and follows a progressive, structured timeline designed to restore range of motion (ROM), strength (especially quadriceps), neuromuscular control, Functional performance, as well as confidence and psychological readiness.

Here’s a general timeline of what to expect:

0–6 Weeks Post-Op:

Early Rehab

Goals will include reducing swelling, restoring full knee extension, initiating quadriceps activation, and regaining 90°+ of knee flexion. 

Key activities performed in this phase will include range of motion exercises, patellar mobilizations, and neuromuscular re-education exercises. 

Key benchmarks to consider are the ability to walk without crutches and achieve full knee extension.

6–12 Weeks:

Strength & Control Phase

Goals will include regaining muscle strength in the legs, improving single-leg control, and normalizing gait mechanics. 

Activities performed in this phase will include closed kinetic chain exercises such as squats and step ups, balance training, bike riding, and resistance training. 

Key benchmarks to consider are increasing quadriceps strength symmetry.

3–6 Months:

Functional Strength & Running

Goals include building endurance and power! Generally, this is where people return to light impact activities and return to running. 

Key activities in this phase will include jump training, agility drills, and return to running progressions.

Key benchmarks to consider are no pain or swelling in the knee, quadriceps strength symmetry greater than or equal to 80%, full range of motion, and good dynamic knee control as progressions are made with jumps and running.

6–9 Months:

Sport-Specific Training

Goals in this phase include restoring plyometric and agility capacity, optimizing movement patterns under load, and preparing for return to sport.

Key activities will include hopping, cutting, pivoting, and progressions through sport-specific drills.

Key benchmarks to consider are limb symmetry of hop tests and quadriceps strength progressing to greater than or equal to 90%.

9–12+ Months:

Return to Sport

Return to sport (RTS) is not time-based alone — it requires passing strict objective criteria and demonstrating both physical and psychological readiness. Athletes who return too early have a significantly higher risk of re-injury, especially under the age of 25.

Gold-standard RTS criteria:

Limb symmetry index (LSI) ≥ 95% on quad strength testing

LSI ≥ 95% on all hop tests 

No pain or swelling

Completion of a progressive return-to-sport program

Psychological readiness (often measured by the ACL-RSI Scale)

Key Benchmarks & Tests for Safe Return

Test: Target LSI: Purpose:

Isokinetic Quad Strength ≥ 95% Assesses quadriceps recovery

Hop Tests. ≥ 95% Measures functional power & control

Y-Balance Test ≥ 95% Assesses dynamic balance

Psychological Readiness (ACL-RSI) High score Assesses fear, confidence, & motivation

Note:

RTS is often cleared no sooner than 9–12 months.

Research shows waiting at least 9 months reduces risk of reinjury by over 50%.

Final Thoughts:

Patience & Persistence Pay Off

Rehabbing an ACL injury is a marathon, not a sprint. It’s normal to experience plateaus, mental fatigue, or fear of reinjury. But sticking to a structured plan, meeting key strength and functional benchmarks, and working closely with your surgeon, physical therapist, and athletic trainer will give you the best shot at a successful, safe return to sport.