Return to Sport after an ACL reconstruction with Wouter Welling

Interview insights Rehab Prevention
Knee being taped for rehabilitation
Photo by cottonbro


What can we do to let athletes return to their sport (RTS) after an ACL reconstruction? Making the decision as to when an athlete is ready for RTS is not an easy one. Before surgery, more than 90% of patients expect RTS without any restrictions. Unfortunately, only 65% of amateur athletes return to their pre-injury level of sports. Furthermore, patients who RTS have a relatively high risk for a second ACL injury (up to 23%), especially for patients younger than 25 years. We had the chance to talk to Dr. Wouter Welling, who has spent years working with ACL patients and has finished a Ph.D. on the topic of RTS after an ACL reconstruction (ACLR).

After his degree in Human Movement Science, Wouter has worked with elite athletes in soccer (e.g. FC Groningen, FC Emmen), volleyball, and basketball during his 6 years at the medical center MCZ in the Netherlands. Because of this work, Wouter had gathered a lot of data on and experience with ACLs so a Ph.D. was the logical next step. Then, under supervision of his Ph.D. team (Prof. Dr. Koen Lemmink, Dr. Anne Benjaminse, Dr. Alli Gokeler), he worked on his dissertation the last few years. Now, Wouter works at Pro-F Physiotherapy, where he is combining his scientific and practical knowledge to objectify RTS, injury prevention, and sports performance for amateur and professional athletes.

Wouter Welling’s research on RTS after ACLR

Currently, RTS decisions are mostly based on subjective criteria. It is therefore unknown whether a patient is physically and mentally ready for RTS. The goal of Wouter’s research was to objectify this RTS process. Which tests are best used to make the RTS decision? How can this be done efficiently without using very complex and expensive equipment? And how can the insights of the research be used by practitioners?

Wouter’s publications can be found here. Together with Wouter, we have summarized the key insights from his research hereunder.

1. Developing a test battery based on existing research: patients do not meet the RTS criteria

First of all, they created a test battery to determine whether an athlete after ACLR is ready for RTS based on the existing literature. This test battery included different variables, such as strength, hop tests, technique, and psychological aspects. When using this test battery with athletes who were 6 months after their ACLR, only 2 out of 28 athletes passed all criteria. One could conclude that the rehabilitation time of 6 months is simply not long enough and that athletes need more time to be physically and mentally prepared for RTS.

In a second study, however, they measured whether athletes would perhaps score better after 9 months. Here, still only 11% passed all criteria. Quadriceps strength revealed persistent deficits. Therefore, their hypothesis became that the quality & intensity of revalidation was below standards. In other words, are physiotherapists letting the athletes train hard and long enough for RTS?

2. Progressive strength training after an ACLR is key & increases the likelihood of actually returning to their sport

Together with Bart Dingenen, they looked at what happens if they let athletes train more regularly and more intensely during rehabilitation. As a result, they found that progressive strength training restores the quadriceps and hamstring muscle strength within 7 months after ACLR. Although strength is just one factor of the rehabilitation process after an ACLR, it is a very important one since many athletes seem to lack sufficient strength in their injured leg. Based on these 3 studies, they concluded that it is important to focus on the quality and intensity of the rehab process, which will determine whether the athlete attains the RTS criteria.

Crucial is the question of whether better results in the RTS criteria lead to a higher chance of actually returning to their sport. In a 4th study, they clearly found that meeting the RTS criteria results in a greater likelihood for RTS. The RTS criteria fail, however, to identify patients who are at risk for a second ACL injury.

In addition, his research group conducted other studies in which they found that the non-injured leg is not always a good reference for the injured leg when analyzing test results. Also, they found that analyzing movement technique is important before RTS, since abnormal movement patterns were found in the injured leg compared to the non-injured leg.

Progressive strength training in the form of a deadlift
Progressive strength training image

3. Next steps for RTS after an ACLR: research & practical side

Wouter’s research has a very practical element: the test batteries and criteria they used are clearly outlined in the papers. Therefore, other practitioners can use these tests in their own practice with just a handheld dynamometer and a phone camera. Besides that, Wouter believes that future research should focus on diving deeper into RTS. RTS, he says, is a continuum and not just a static moment in time with a simple yes/no question. It is important to distinguish between different phase in rehab like return to running, return to training, or return to competing.

On top of that, it is important to make the translation from the clinical setting to the field setting. How does an athlete actually perform on the field? Are they able to accelerate, decelerate, take sharp turns? Can we add sport-specific elements (dual tasks) in the rehabilitation for training reactive agility? These are important factors that are not measured in the clinical tests.

4. RTS after an ACLR with the Hylyght platform

In the Hylyght platform, we have tests & benchmarks that can be used to rehab an athlete after an ACLR. These tests & benchmarks are based on existing research and we will implement these latest findings with Wouter as well. Consequently, it becomes much easier for practitioners to test their athletes and make sure they are ready for RTS after an ACLR without having to check benchmarks and the newest research themselves.

Interest in testing your athletes or patients?

If you are a sports organization in The Netherlands and would like to rigorously test your athletes, you can get in touch with Pro-F Physiotherapy via Wouter Welling. If you’re interested in using our software to test athletes for RTS after a wide variety of injuries, you can contact us.