Dr. Yi-Cheng Wu
中文

Post-Operative Rehabilitation Assessment After ACL Reconstruction

By Dr. Yi-Cheng Wu · Reviewed June 21, 2026

Rehabilitation after ACL reconstruction often takes 6–12 months, following a staged, progressive approach combined with multi-dimensional assessment.

Rehabilitation after ACL reconstruction is usually long and typically follows a staged approach: the early phase focuses on easing pain, reducing knee joint effusion, and gradually restoring range of motion and weight bearing; it then progresses to strength and proprioception training, with return to sport as the final goal. Research suggests early weight bearing and activity were relatively safe and helped recovery in the studies reviewed, and it is recommended to keep the side-to-side strength difference within 10%. Whether someone can return to the field is judged by combining patient-reported outcome scales, strength metrics, and functional tests, with ongoing fine-tuning based on the individual's recovery; the whole process usually takes 6–12 months. The actual plan depends on your condition and a physician's assessment.

Stages of post-operative rehabilitation after ACL reconstruction

  1. Early phase: reduce swelling, ease pain, and restore range of motion

    In the first weeks after surgery, the focus is on easing pain, reducing knee joint effusion, and gradually restoring knee range of motion (ROM) and beginning weight bearing. Research indicates that early, moderate weight bearing and activity were relatively safe and helped reduce later joint stiffness. This phase also favors closed-kinetic-chain exercises to reduce loss of thigh muscle strength in the lower limb.

  2. Strength and proprioception training (within about 3 months)

    In the strengthening phase, the focus is on quadriceps and hamstring strength training (including eccentric quadriceps work) and proprioception training, aiming to keep the side-to-side strength difference within 10%. For high-risk young female athletes, adding neuromuscular training is also recommended to reduce the risk of re-injury.

  3. Skill and sport-specific training (within about 6 months)

    Once strength and joint function have recovered to a certain level, sport skills and sport-specific training are gradually added, moving movement patterns from basic rehabilitation toward the demands of actual sport.

  4. Return-to-sport-focused training (months 6–12)

    The final phase trains with return to play as the goal, and progression requires passing the assessment targets set for each stage. This progressive process usually takes 6–12 months, and the actual pace is continually fine-tuned by the physician, physical therapist, and coach based on the individual's recovery, goals, and compliance.

Some of the active patients seen in clinic are recovering from surgery, and each procedure has its own particular rehabilitation needs. Cruciate ligament injuries are not uncommon in sports such as basketball, soccer, and volleyball. Once you decide to have surgery, you cannot simply hope the operation goes smoothly — the rehabilitation before and after surgery matters just as much as the surgery itself, since a good rehabilitation process helps reduce pain, restore function, and return to the field as soon as possible.

Rehabilitation after ACL reconstruction is usually long and demanding. Most patients want to improve their symptoms effectively and return to sport early as their main goals. Beyond rehabilitation and training, the physician and other professionals need to keep assessing the patient’s condition in the hope of lowering the risk of re-injury. These assessment methods combine clinical evaluation, functional testing, and patient feedback. Although the testing methods are varied, the research evidence for accurately predicting whether someone can return to play is quite limited.

General principles of post-operative rehabilitation and sport training

The goal of surgical reconstruction is to restore the structure and function of the ligament within an acceptable timeframe, while also lowering the risk of near-term acute injury and future chronic degeneration. Traditional rehabilitation programs aim to restore knee range of motion and begin weight bearing in the first few weeks, gradually progressing to strength and proprioception training within 3 months, adding skill and sport training within 6 months, and then, during months 6–12, training with return to the field as the goal.

Every training program needs to be adjusted according to each person’s recovery, how ambitious their goals are, and their compliance with the training plan.

The initial clinical management is to ease pain and reduce knee effusion, gradually restore range of motion, and limit the loss of thigh muscle strength in the lower limb. Through strength training, the aim is to keep the side-to-side strength difference under 10% in the future. Related research is growing, and some systematic reviews have found that early weight bearing and activity were safe and beneficial for the recovery outcome, helping to reduce later joint stiffness.

Closed-kinetic-chain exercises are best in the first 3–4 weeks, and the subsequent eccentric quadriceps training that goes with them is very important. Although wearable devices such as knee braces are worn for a while by most patients after surgery, together with related rehabilitation exercises, no study strongly recommends that wearing a knee brace offers a clear advantage.

In high-risk young female athletes, neuromuscular training for the anterior cruciate ligament is very important and can reduce the risk of injury. For example, the FIFA 11+ warm-up developed by the football association is a good demonstration of this. Neuromuscular training during rehabilitation may also reduce the risk of ACL re-injury.

Return to the field is the ultimate goal. However, the current challenge is a lack of validated tools, which makes it hard to judge how high the risk of re-injury is or to give an objective standard for return to play.

The whole recovery process is made up of many factors together. Most current rehabilitation and sport-training protocols use a staged approach: only when you improve your current deficits and meet the goals of that stage can you progress to the next one. Most protocols currently have 6–8 stages, and passing the assessment targets and completing training take 6–12 months before there is a chance to return to the field.

Assessment methods

Regarding the recovery process, the main areas assessed can be divided into several dimensions, including patient-reported outcomes (PRO), strength metrics, and functional testing.

PRO (patient-reported outcomes)

Current research mostly uses scales such as the KOS (knee outcome scores), the Global Rating Scale (GRS), and the International Knee Documentation Committee (IKDC). Many people recommend using the IKDC because it includes data across different ages, sexes, and a normal population. There is also a web-based version that calculates the score for you.

Strength metrics

The current consensus, based on past clinical experience, is that symmetric quadriceps and hamstring strength is a marker of successful return to play, so the threshold of the limb symmetry index (LSI) is set at greater than 90%. Although one study testing women after ACL surgery found that strength symmetry did not reduce subsequent ACL injuries, most current research still focuses assessment on strength changes at 60- and 180-degree angular velocities.

In addition, the hamstring-to-quadriceps strength ratio (H/Q ratio) is used to assess the strength balance around the knee. However, it currently applies only to young women and can be compared with normal values, and this metric still has some drawbacks to overcome — for example, whether the difference in the ratio can be used to predict injury risk (see the article: The art of interpreting and applying the Q:H ratio).

Functional testing

Common tests are those involving jumping or hopping for distance.

Watch the related demonstration video on YouTube

Drop Vertical Jump test (DVJ)

Using a force plate to capture the results of movement mechanics has been shown to help assess ACL injury risk and training effects in female patients, and an excessive abduction moment can predict the risk of re-injury.

Landing Error Scoring System (LESS)

The LESS uses video to assess the DVJ landing across 17 items. Research has found a strong association with ACL injury in women. There are some simplified versions, but they have less robust research support.

Others include hop tests (the single-leg hop for distance is the most common), the Star Excursion Balance Test, and more, all of which have some research support. Some integrated assessment scales, such as the MRSS (Melbourne Return to Sport Score), have also been used in some studies.

Summary

All of the methods above are assessment methods used in research, and they are a great help for clinicians in understanding recovery. However, there is still no clear, objective standard that can accurately predict the timing of return to play or fully account for the risk of re-injury. To me, this reflects the idea that the research still has work to do and the revolution is not yet complete.

In current clinical and training practice, physicians, physical therapists, and coaches all fine-tune the training items and return-to-play timing based on the assessments above. Although it is not possible to predict the return-to-play timing accurately from the start, through this step-by-step process of fine-tuning the difference is usually not too large.

It is a pleasure to move forward together with such a strong group of partners. Keep it up!

References

  • A systematic review of anterior cruciate ligament reconstruction rehabilitation: continuous passive motion, early weight bearing, postoperative bracing, and home-based rehabilitation. J Knee Surg. 2008 Jul;21(3):217-24.
  • Quadriceps function following ACL reconstruction and rehabilitation: implications for optimisation of current practices. Knee Surg Sports Traumatol Arthrosc. 2014 May;22(5):1163-74.
  • Consensus criteria for defining ‘successful outcome’ after ACL injury and reconstruction: a Delaware-Oslo ACL cohort investigation. Br J Sports Med. 2015 Mar;49(5):335-42.
  • A decision-making scheme for returning patients to high level activity with nonoperative treatment after anterior cruciate ligament rupture. Knee Surg Sports Traumatol Arthrosc. 2000;8(2):76-82.
  • The Landing Error Scoring System as a Screening Tool for an Anterior Cruciate Ligament Injury–Prevention Program in Elite-Youth Soccer Athletes. J Athl Train. 2015 Jun; 50(6): 589–595.

Further reading

Frequently asked questions

What general principles does rehabilitation after ACL reconstruction usually follow?

It usually follows a staged approach: the first few weeks restore range of motion and weight bearing, then progress to strength and proprioception training, and only in the later phase are skill and sport-specific training added, with return to sport as the goal. Research suggests early weight bearing and activity were relatively safe and helped reduce later joint stiffness; the whole process usually takes 6–12 months and is adjusted according to the individual's recovery, goals, and compliance.

What methods are used to assess recovery during rehabilitation?

Assessment is mainly divided into three areas — patient-reported outcomes, strength metrics, and functional testing. In clinical practice these assessments are combined to understand how recovery is progressing.

What tools are commonly used for patient-reported outcomes (PRO)?

Studies commonly use scales such as the KOS, the Global Rating Scale, and the IKDC. The IKDC is recommended by many because it includes data across different ages, sexes, and a normal population, and an online version is available to help with scoring.

How are strength metrics interpreted?

A limb symmetry index (LSI) greater than 90% is commonly used clinically as a reference, along with attention to the balance between quadriceps and hamstring strength. However, some studies indicate that strength symmetry does not necessarily reduce the risk of re-injury, and these metrics still have limitations to overcome.

What does functional testing include?

Common tests include hop tests such as the single-leg hop for distance, the Drop Vertical Jump test (DVJ), the Landing Error Scoring System (LESS), and the Star Excursion Balance Test. Some studies show associations with ACL injury risk in women, but there is still no unified, objective standard that accurately predicts return to play.

This article is also available in the original Chinese, with the full reference list.

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