ACL Rehabilitation: Rehabilitation Planning

Original Editor - Mariam Hashem

Top Contributors - Mariam Hashem, Wanda van Niekerk, Jess Bell, Kim Jackson, Tony Lowe, Tarina van der Stockt, Simisola Ajeyalemi, Chelsea Mclene, Robin Tacchetti, Rachael Lowe, Leana Louw, Abbey Wright and Olajumoke Ogunleye  

Introduction

Rehabilitation after an ACL reconstruction (ACLR) is key to optimising clinical outcomes. The main goal is usually for the person to return to their sport or activity and perform at the same level as before the injury. Evidence shows that around 80% of patients after ACLR return to some form of sporting activity, but only 65% return to the same level as before their injury, and only 55% return to sports at a competitive level.

Despite the volume of research in this area, ACL rehabilitation protocols vary, and there remains a lack of consensus on standardised progression criteria for return to sport. What remains consistent across the literature, though, is the importance of setting clear goals, such as reducing pain, swelling and inflammation, establishing full knee range of motion (ROM) and neuromuscular control, and returning to pre-injury physical and sports activity levels. Clinicians should, therefore, follow a progressive, criteria-based rehabilitation approach, applying clinical and impairment-based criteria to determine readiness for return to sport. 

One challenge in managing a patient with an ACL injury is that it is, by nature, a long-term injury. The ability to plan meaningfully across the complete timeframe is a necessary skill for clinicians. This page addresses how to approach that planning process — from the post-surgical considerations that shape the early weeks, through the physiological principles that underpin exercise prescription, to the structure of a week-by-week programme.

Considerations Before Setting up a Plan

Before constructing a long-term rehabilitation plan, clinicians should understand the restrictions guiding the early post-operative period. The priority is to protect the surgical repair and allow healing without compromising ROM.

Range of motion

Range of motion is not typically prohibited after surgery, and immediate knee mobilisation can be implemented following ACLR. Patients should be encouraged to move through their available range, both actively and passively, within the limits of their pain tolerance. Early restoration of ROM is a key factor in successful outcomes following ACLR. Continuous passive motion devices are not recommended, as evidence shows no additional benefit for pain, range of motion or swelling compared to active motion exercises.

Bracing

Most clinical practice guidelines do not require post-surgical bracing, though the APTA guideline allows for an immediate postoperative knee brace to be used based on the patient’s preference or associated ligament injuries. In practice, bracing decisions are surgeon-, clinician- and context-dependent. Some surgeons or clinicians prefer placing the knee in an immobilising brace, which is then replaced with a hinged functional knee brace once the femoral nerve block wears off. The main purpose of bracing is to prevent reinjury in the acute stage, and the need for it depends on the environment. For example, bracing may be essential if the patient is at risk of slipping due to snow, whereas a safer environment may not warrant it.

Weight-bearing

Newer protocols and guidelines encourage early full weight bearing (within the first week), “but clinicians are advised to progress as tolerated.” Some clinicians prefer a short period of partial weight-bearing in the first two weeks following surgery to promote healing and restore joint homeostasis. The use of crutches for partial weight bearing also allows for a more symmetrical gait pattern during the early stages after surgery.

Stationary bike

The use of a stationary bike is often introduced on day 10 or once 110° knee ROM is achieved. The amount of loading can easily be controlled via the resistance setting on the bike. If range is still slightly limited, a U-shaped cycling style is allowed to begin with.

Resistance training

Resistance weight-bearing strength training is typically delayed until 6 weeks after surgery to avoid scar hypertrophy and stiffness. However, Andrade et al. reviewed recommendations from clinical practice guidelines and reported that most guidelines recommend that strength and neuromuscular training should be used in most phases of postoperative rehabilitation.

If you'd like, you can review the acute management goals after ACL reconstruction here.

Following the first 6 weeks of acute management, the clinician can begin to construct a longer-term rehabilitation plan. Setting specific goals and milestones is important, and mapping timeframes to these goals helps structure the process. However, time alone should not dictate progression — relevant, objective criteria and individual patient needs are most important.

Mid-stage Rehabilitation Goals

The mid-stage of rehabilitation generally spans weeks 6 to 24 post-ACLR. Goals during this stage should include addressing deficits associated with neuromuscular function. This can include muscle and joint-specific strength imbalances, closed kinetic chain strength and basic motor patterns. A fitness reconditioning programme should also be included, not only to avoid detraining, but also to ensure optimal fitness when returning to sport.

Buckthorpe and Della Villa recommend dividing the mid-stage into two blocks based on knee load tolerance and functional capacity.

During the first block (approximately weeks 6 to 12), the knee cannot tolerate high loads, and quadriceps weakness limits land-based functional training. During this foundation-building phase, the focus should be on isolated strengthening exercises, such as leg press and knee extension, typically performed at 12 to 20 repetitions with lower intensity. The pool is useful for functional movement practice, allowing patients to perform squats, lunges and gait training at 40 - 60% reduced body weight.

The second block (approximately weeks 12 to 18 or 24) represents a functional integration phase as knee load tolerance improves and leg symmetry index (LSI) typically exceeds 70%. The focus in this block shifts towards a balanced mix of isolated and functional strengthening exercises performed at a moderate intensity for 8 - 12 repetitions. Running can be introduced during this phase if appropriate criteria are met, with treadmill-based gait re-education and progressive walk-run protocols.

This structuring ensures that rehabilitation intensity and exercise selection match the knee's load tolerance and the patient's functional capacity.

Recommended criteria for progression from the early mid-stages of rehabilitation are summarised in Table 1.

Table 1. Recommended criteria for progression from early to mid-stage rehabilitation after ACLR.

Outcome measure	Test	Goal
Pain	Numeric pain rating scale	0 - 2
Swelling/effusion	Stroke test	Zero to traces of effusion
Passive knee extension	Prone hang test	0 degrees
Passive knee flexion	Goniometer measurement in supine or prone	At least 120 degrees of knee flexion
Quadriceps recruitement	Full recruitment	No lag on single leg raises, 10 repetitions
Walking gait	Assessment of gait	Normalised gait with no aid

Table 2 shows the recommended criteria to progress from mid-stage to late-stage rehabilitation.

Table 2. Recommended criteria to progress from mid to late-stage rehabilitation after ACLR.

Outcome	Test	Goal
Knee effusion	Stroke test Knee circumference measurement (changes of more than 1 cm at the patella are clinically relevant)	Zero effusion and minimal activity-related swelling (less than 1 cm in knee circumference measurement at the patella)
Knee ROM	Same as for mid-stage entry criteria	Full range of motion
Knee strength (extensors and flexors)	Isokinetic testing - alternating knee extension and flexion concentrically at 90° s-1 for 4 repetitions and 180° s-1 for 20 repetitions	LSI > 80% for knee flexors and extensors and a >0.60 F/E ratio
Muscle strength (closed chain)	Leg press strength test (90° knee flexion and seat at 45° - maximal weight achieved for 8 RM) OR Isometric single squat (single leg 60° knee flexion on force plate - person should stand below a fixed bar to ensure testing rigour)	Minimum of 125% of body mass (BM) for 8 RM (repetition maximum) or 1.5 x BM predicted 1 RM OR Peak force > 150% body mass
Gluteal muscles	Single-leg bridge test	More than 20 repetitions and within 5 repetitions of each side - no cramping of hamstrings or adductors
Calf muscles	Single-leg calf raise (one foot on a step, perform calf raise through full ROM)	More than 20 repetitions and within 5 repetitions of each side
Balance	Single leg balance in standing, arms crossed over chest. First with eyes open and then with eyes closed	Eyes open - 43 seconds Eyes closed - 9 seconds (based on normative data)
Quality of movement	Single leg squat test (squat to at least 60° knee flexion with minimal trunk and pelvic motion, no hip adduction or internal rotation)	Good movement quality
Running gait	Assess running gait at 8 - 10 km h-1 (assess running mechanics - control of alignment in frontal and sagittal planes)	Normalised running gait and able to run for > 10 min at 8 km h-1

If you would like to learn more about the early and late phases of rehabilitation, see ACL Rehabilitation: Acute Management after Surgery and ACL Rehabilitation: Re-injury and Return to Sport Tests.

Remember, rehabilitation and return to sport decisions should focus on "how" the athlete returns instead of "when". Time does play a role and is necessary, but time alone does not guarantee successful outcomes.

Creating a Plan

As a physiotherapist, you have a role in guiding your patient through a long-term rehabilitation plan. Setting milestones and goals depends on your patient's needs and desired level of function. Evidence shows that goal setting improves self-efficacy and, importantly, adherence during rehabilitation. Using clinical experience and reasoning to predict outcomes and time frames for each goal is an important part of the process.

Building on the two-block framework described above, the rehabilitation planning process can be organised into nine phases, with the muscular endurance, strength and power phases forming a large part of mid-stage rehabilitation.

The Nine Phases of the ACLR Rehabilitation Plan

Range of motion

This phase starts immediately after surgery and lasts up to the sixth week. The focus is on maintaining the available range, facilitating the return of full ROM, managing effusion and inflammation, and achieving knee terminal extension. Achieving full knee extension in the early stage of rehabilitation doesn't affect the stability of the graft.

The goal is to reach 120° of flexion within four weeks after surgery, with full symmetrical flexion by 12 weeks. ROM exercises can progress from active-assisted knee flexion off the side of the bed and progress to wall slides, active-assisted sitting, and doing a half a circle movement on a stationary bike.

Increase weight-bearing tolerance gradually

This phase applies primarily to patients with concurrent meniscal or chondral injuries, where weight bearing may be restricted for up to six weeks. In these cases, a gradual increase in weight-bearing tolerance is needed before progressing to strengthening. For an isolated ACL reconstruction, the transition from partial to full weight bearing at two weeks is typically straightforward and does not require a dedicated tolerance-building phase.

Building muscular endurance

Muscular endurance is the ability to exert work for an extended period and resist fatigue. Exercises should be performed at a light intensity (<50% of 1-RM) for 15-20 repetitions, three or more sets, with less than 60 seconds of rest. Training frequency should be two to three times weekly, with 48 hours rest between sessions. The timeframe for this phase depends on joint pathology and may take up to eight weeks, typically spanning weeks 10-18 of rehabilitation.

Examples of exercises to use during this phase are: wall squat holds, total body resistance squats, single-leg shuttle squats, supine bridge with hamstring curl, resisted lateral steps, and alternating lunge holds.

Moving from endurance to strength training can start when the athlete meets the following criteria:

• ability to walk on a treadmill or cycle with resistance for 20 minutes.
• similar active ROM to the opposite side
• back leg squat/leg press for 10 repetitions at >70% of the predicted 10 RM.
• 15 repetitions of a single-leg squat from a 10-inch step/box
• anterior reach on the Y-Balance test within an 8 cm difference from the opposite leg
• quadriceps index > 80%

Developing strength

Strength is the ability to exert force or torque at a specific speed. This phase typically spans weeks 19 to 26 of rehabilitation. Hip, knee and ankle muscle weakness are common following ACL injury, with knee flexor and extensor weakness persisting for longer periods after surgery. It requires moderate to heavy loads (at least 60-67% of 1-RM), with resistance progressed frequently. Depending on the patient's previous level of strength, exercises are performed for 1-12 repetitions, one to three sets, with two minutes rest between sets. Every four weeks, a week of de-loading is recommended to allow recovery (with a resistance of 50-60% 1-RM).

Exercise selection during this phase depends on the muscle groups being targeted. For example, a 30–40 minute lower body session might be structured as follows:

Muscle	Example
Quadriceps dominant	Leg press
Glutes dominant	Single leg bridge
Hamstrings dominant	Romanian deadlift
Quadriceps dominant	Tuck squat
Quadriceps dominant	Single leg squat
Hamstrings dominant	Hamstrings lean/Nordic hamstrings curl

Further examples and more on the progression of exercises are found in table 6 in this article.

Muscular power

Muscular power is a combination of force and velocity. This phase typically spans weeks 27-32 of rehabilitation. Training for force requires high loads (85-100% of 1 RM) for one to three sets, with three minutes of rest between sets. Developing velocity requires lower resistance (about 30% 1 RM) for six repetitions, one to three sets, with three minutes of rest between sets.

Starting power training should begin when the athlete shows the following criteria:

• ability to run for 20 minutes
• back squat/leg press at 80% of the predicted 10 RM
• anterior reach distance within 4 cm difference from the opposite leg on the Y-Balance test
• thigh girth within 1 cm compared to the contralateral side
• quadriceps index at 90%
• hamstrings to quadriceps ratio of 60%, using a handheld dynamometer
• passing the single-leg drop test

Building running tolerance

Not all sports require the same amount of running, so the running programme should be tailored to the athlete's needs. This phase typically begins around week 27 and spans four to six weeks. The Vail sports test can help assess how the athlete loads their injured knee, which will influence running.

You can start a running programme when the athlete’s quadriceps index exceeds 80%, ensuring that running mechanics are as close to normal as possible. A recent clinical practice guideline suggests the following criteria for return to running:

• 95% knee flexion ROM
• full extension ROM
• no effusion/ trace of effusion
• LSI > 80% for quadriceps strength
• LSI > 80% eccentric impulse during countermovement jump
• pain-free aquajogging and Alter-G running
• pain-free repeated single-leg hopping

Running tolerance should be increased gradually over up to 4 weeks. Using an Alter-G treadmill or pool running is useful for initiating partial weight-bearing, increasing by 5% each session until full weight-bearing is achieved. A walk-run protocol can be useful. You might start with four minutes of walking followed by one minute of running, repeated four times over 20 minutes, two to three times weekly. Each week, the running segment can be increased by one minute, and the walking segment can be reduced by one minute, until the athlete can run continuously for a progressive 20 minutes. If any signs of overload are present, the athlete should return to the previous stage of running progression.

Speed and agility training

Speed and agility are important for reconditioning and return to sport. Build a specific drills programme depending on your patient's sport-specific needs. For example, at week 32, introduce unidirectional drill training for a week, then progress to multi-directional training.

By the end of this phase, the athlete must be able to:

• pass the modified T-test
• pass single leg hop series with >90% symmetry compared to the opposite side
• complete ten repetitions of a squat or leg press with >90% of the predicted 1RM

Return to training and return to play

For professional athletes, the minimum criteria to be cleared from clinic-based rehabilitation and to begin training with a coach or team are listed below. From this point, a gradual return to full participation should be implemented.

• no pain or swelling
• full knee ROM
• stable knee (pivot shift, Lachman, instrumented laxity evaluation)
• normalised subjective knee function and psychological readiness (IKDC, ACL-RSI, TSK)
• isokinetic quadriceps and hamstring peak torque at 60°/ s should display 100% symmetry for a return to pivoting sports
• countermovement jump and drop jump > 90% symmetry of jump height and concentric and eccentric impulse
• jumping biomechanics — normalised absolute and symmetry values for moments, angles, and work in vertical and horizontal jumps, especially in sagittal and frontal plane at hip, knee and ankle
• running mechanics — restoration of > 90% symmetry of vertical ground reaction forces and knee biomechanics during the stance phase of high-speed running and change of direction
• completion of a sports-specific training programme

Timeframes vary among sports, and the phases outlined above are suggestions to guide planning for the clinician and the athlete.

Read more about return to play and return to play testing here.

Weekly Plan

When setting a weekly plan, consider the athlete's priorities and the required levels of different physiological characteristics.

The following is a suggested weekly plan for an athlete whose top priority is lower body strength, alongside cardiovascular fitness, core stability and upper body strength. This plan includes four lower-body strengthening sessions, two cardio sessions, two pool sessions, two core sessions, and two upper-body strengthening sessions.

Monday	Lower body strengthening + cardio
Tuesday	Lower body + upper body strengthening
Wednesday	Low load recovery (core stability + pool exercise)
Thursday	Same as Monday
Friday	Same as Tuesday
Saturday	Same as Wednesday
Sunday	Off

Knee Symmetry

Achieving as much symmetry as possible between the injured and uninjured knee is essential for recovery and return to function after ACLR. Asymmetries in loading can lead to strength deficits, which in turn reinforce abnormal loading patterns. Symmetry means equal ROM and equal strength — a loss of as little as 2° of extension and 5° flexion, compared to the other knee, has been associated with lower subjective outcome scores.

Research supports the importance of symmetry for long-term outcomes. Hetsroni and colleagues found that maintaining participation in sports 5-10 years after ACL surgery was associated with symmetry in muscle torque and landing kinematics. Cristiani and colleagues found that symmetrical isokinetic quadriceps strength and single-leg-hop test performance at 6 months post-ACL surgery consistently increased the likelihood that a patient would achieve a PASS (i.e. patient-acceptable symptom state) on the KOOS at 2 years. When the surgical graft is obtained from the contralateral leg, it is essential to regain ROM in both knees during rehabilitation.

It is important to note that symmetry measured using the LSI can be misleading. The LSI often fails to account for pre-injury strength of the reconstructed side, muscle strength changes (decreases or increases) of the uninjured side, bilateral deficits and compensatory movement strategies. For example, a patient may achieve 90% LSI not because their injured leg is strong, but because their uninjured leg has also weakened. Clinicians should consider absolute strength values as well, not just symmetry.