ACL Injuries

Injury to the ACL (anterior cruciate ligament) is one of the most significant knee injuries seen in sports. Injury to this knee can be traumatic, or it can be a non-contact injury. The ligament itself plays a role in knee stability, stopping anterior translation of the tibia. Essentially, this means that it helps your femur and your tibia stay intact, and an injury to said ligament, can result in instability of the knee.

There is growing research on the benefits of trying to rehab an ACL tear, rather than opting for surgery straight away. However, this is very patient specific, and dependent on your symptoms, your Orthopaedic Consultant may advise you on the best course of treatment. In the case of an ACL reconstruction, rehab usually takes 9-12 months before the athlete can return to their sport. A disturbing occurrence has been ‘gurus’ selling accelerated programs taht can get you back to your sport at 6 or 7 months, which the research doesn’t support. The level of recovery required is almost impossible to reach in this time, and athletes run the risk of a re-rupture if they rush back too soon.

If you have been rehabbing your ACL injury with your physiotherapist, it has probably been mentioned during your rehab process what tests you have to pass before returning to sport. Dependent on what clinic you’re attending and what facilities are available, return to sport testing can vary greatly from clinic. In this article, we will discuss 5 non-negotiable tests when considering if you’re ready to return to play.

1. Knee Swelling, Range of Motion, and Stability

Immediately after an ACL injury, most athletes will remember the haemarthrosis, or significant swelling that appears soon after the injury. This swelling can be a constant reminder both prior to surgery, and for the weeks/months following surgery. A primary aim of any good physio immediately post ACL surgery, is to try and keep swelling to a minimum, an teach the athlete ways to minimise swelling, and eradicate it prior to moving onto the next level of rehab. Prior to return to sport, an athlete’s knee should not be swelling up after exercise.

Range of motion can be significantly reduced post surgery. Athletes often find it challenging to regain full extension (straightening your knee fully) and regaining full flexion (bending your knee as much as your non-injured side. Knee extension should be full within the first few weeks of rehab, and flexion should be at a minimum, 90% of the range of motion of the non-injured side. Having a surgically repaired knee with no swelling and full range of motion, can sometimes be referred to as a ‘quiet knee’.

Instability is a primary driver for some people to get the ACL surgery in the first place. Knee instability makes high performance in most sports very challenging, if impossible. Stability should be regained as part of your rehab process. We can measure stability both statically, and dynamically. Static stability is measured by your physiotherapist using tests such as the Lachman’s Test, or the Anterior Draw Test. Dynamic stability can be self-reported by the athlete. Does your knee feel stable in your day to day activities? Do you ever feel your knee buckle underneath you? Regaining stability is pivotal for confidence to return to sport.

2. Leg Strength Symmetry

Measuring the differences in leg strength starts from very early on in your rehab process. It may serve as a guide whether things are going well, or if particular focus need to be placed on a certain movement pattern, or muscle group. Difficulties may arise dependent on which type of ACL graft you had. Common ACL grafts are from the patella tendon, the quad tendon, the semitendinosus tendon (hamstring), or a donor tendon (from a cadaver). If a graft is taken form one of your own tendons, it is known that it will require much more effort to increase strength parity, as you have had some of your tendon removed, which does not grow back. Therefore, the target of 90% limb strength symmetry can be challenging.

Strength in the past has been measured by manual muscle testing (the physio putting their hand on you and asking you to push). Although this is fine in early stages to measure pain and progress, this level of testing is not appropriate for return to sport. It is not accurate enough as it is far too subjective, and it is impossible to quantify the difference between the legs. In return to sports testing, your physiotherapist should be using either a boded machine, a handheld dynamometer, or force plate technology. Anything below this technology and you’re just flipping the coin essentially as it is not accurate. We want at least 90% parity amongst all lower limb muscle groups, including quads, hamstring, calves, and glutes.

3. Functional Testing

‘Functional’ is a term that gets thrown around a lot in the health and fitness space, and can sometimes be confusing. In terms of ACL testing, functional testing encompasses balance testing, hopping tasks, jumping, and landing tasks. Robust testing of these should include: 

• Single hop for distance

• Triple hop for distance

• Side hopping (testing endurance and distance)

• Quad, hamstring, and calf endurance testing

With these tests, the injured side is compared to the non-injured side and we want at >90% symmetry. Distances and reps are important and are measured, but how the athlete moves is also important. In testing, we want to look for compensations, confidence, painful responses, and any other inconsistencies with movement that may increase the risk of re-injury.

4. Sport-Specific Fitness Testing

It is important that before an athlete returns to sport, that their cardiovascular and metabolic fitness is measured. Most injuries happen towards higher levels of fatigue, so fitness is an aspect that should not be overlooked. There are a lot of tests that the research supports, and may be picked dependent on what the athlete’s sport requires of them. Some examples include:

• A Beep Test

• Agility T-Test

• Bruce Protocol

• Illinois Agility Test

• A Timed Run

• Sprint Testing

It is important to pick tests that will be transferable to the athlete’s sport. For example, the Illinois Agility Test contains lots of change of direction and sprinting, which may be an inappropriate test if you’re testing a long distance runner.

It is also important that the functional tasks tested previously are also tested in a fatigued state. You can test these on a second date where the athlete goes on a fatiguing run or does a challenging HIIT Workout or an EMOM for 15-20 minutes prior to performing the tasks.

5. Psychological Testing

The psychological readiness of athletes is often underemphasised, and in high level sports can be brushed under the rug. If an athlete isn’t confident returning to sport, then it is irrelevant how they perform on the physical testing. Some psychological questionnaire that are extremely useful to test psychological readiness include:

• The Tampa Scale of Kinesiophobia (TSK-11)

• The IKDC Subjective Knee Evaluation Form

• The ACL-RS1

If you have any questions on whether physio is the best option for you, or you have any questions about MVMNT in general, feel free to contact via email.

- Jay Towolawi, Specialist Sports Physiotherapist and MVMNT Founder.