While returning to sport after ACL surgery seems like a daunting task, thankfully it is a process well researched. The expected time to return to sport after ACL surgery is at least 9 months, largely due to healing and rehab exercise requirements.
Additionally, an analysis of pivoting sport players found that up until the 9 month mark after ACL surgery, 1 month return to sport delays were associated with a 51% reduction in knee reinjury rates. This further supports the timeline of 9 months minimum for a return to sport. However, current evidence shows that ACL protocols for returning to sport should not be purely time-based, but primarily emphasize achieving specific criteria to determine rehab progression.
This helps to tailor rehab to your individual needs, ensuring that important functional milestones are achieved as part of your return to sport journey.
The Melbourne ACL Rehabilitation Guidelines, are an example of protocol that incorporates a criteria based approach. These guidelines split rehab into 5 distinct phases, with progression from each phase determined by achieving specific criteria. The phases are as follows:
Phase 1: Recovery from Surgery
Phase 2: Strength and Neuromuscular Control
Phase 3: Running, Agility and Landings
Phase 4: Return to Sport
Phase 5: Prevention of Re-injury
Phase 1: Recovery from Surgery
During the first couple of weeks after acl reconstruction surgery, treatment priorities revolve around post-operative recovery. The primary objectives are to get your knee fully straight, reduce swelling and to get your quadriceps effectively contracting
Swelling can be controlled via tubigrip (a compression bandage worn at the knee), elevating the knee above the heart while resting and avoiding physical activity that will aggravate your knee. Ice can also be applied intermittently for 10-15 mins at a time to aid swelling management. Regaining mobility at your knee joint is achieved by exercises for range of motion, such as heel slides .
Quadriceps exercises in this early phase are focused on activation and control. This is achieved by performing ‘static quads’ exercises, in which contractions are practiced in isolation. Quadriceps control with movement is trained by performing straight leg raises, in which the quadriceps work against gravity to keep your knee straight. If the quadriceps are weak or have poor activation, then the effect of gravity will cause your knee to bend. The inability to keep your knee straight against gravity is known as ‘extensor lag.’
Clearing Phase 1 will be determined by achieving the following criteria:
The ability to get the operated knee completely straight
Bending the knee to 125 degrees or more
Being able to complete a straight leg raise without lag
Satisfactory swelling reduction (determined by your physiotherapist).
Phase 2: Strength and Neuromuscular Control
One of the key goals for phase 2 is to regain muscle strength in your leg. Training your quadriceps and hamstrings will be especially important, they are considered the ‘active stabilisers’ of the joint, meaning it is their contractions that help prevent injuries. In the early stages of rehab, body weight exercises like glute bridges, squats and calf raises will be the basis for your rehab program. In the later stage of this phase, strength training will begin to resemble a lower body gym workout, with exercises such as the leg press and back squat (at low loads) being beneficial. Keep in mind that if your surgery was performed using a hamstring autograft, in which a piece of your own muscle was used to help reconstruct the ACL, then hamstring strength training will likely progress at a slower rate to allow for healing.
The other important goal of phase 2 is improving neuromuscular control, which is the muscles’ ability to contract effectively to sensory input to maintain dynamic stability. Helpful exercises to improve neuromuscular control include controlled step downs, single leg balance (on a BOSU board for higherlevel training) and single leg star excursions. The importance of neuromuscular control extends to your hip and ankle joints as well, as seen by the image below. As you can see, if the hip and ankle are in the wrong positions it will contribute to the knee position that causes ACL tears. This is why exercises in phase 2 focus on the entire leg and not just the knee, so that the entire limb can maintain appropriate alignment during physical activities.
Clearing Phase 2 is determined by the following criteria:
Sufficient functional alignment during a single leg squat test (determined by your physio)
>85% repetitions achieved with operated leg when compared with the other side, for the following exercises involving the hip, knee and ankle (eg single leg squat)
Single leg balance time of 43 seconds eyes open and 9 seconds eyes closed
Maintaining compliance with phase 1 criteria
Phase 3: Running, Agility and Landings
As the exercises from phase 2 begin to increase in difficulty, phase 3 introduces your knee to higher physical demands involving pivoting, running and landing. Pivoting demands and exercises can be tailored based on your desired return to play sport. For example, basketball requires quick pivoting in tight spaces, so agility ladder drills and cone-based agility drills (as pictured below) will make for effective training. For a sport with a larger playing field, such as football, these changes in direction often occur at higher speeds due to the increased space for player acceleration. In this case, running and cutting drills are appropriate.
Similarly, the distance for running exercises can be determined by what is most appropriate for your chosen sport. 35m sprints are good for team sports, while athletics + endurance running will naturally involve longer distances. Finally, a good way to commence landing training is with crossover hops and scissor jumps, then later progressing to box jumps. Towards the end of phase 3, all three of these areas can be addressed by returning to training at lower intensities. This is the best way to prepare your knee for your own sport specific demands, as well as providing the social benefits of rejoining your team/training group.
Similarly, the distance for running exercises can be determined by what is most appropriate for your chosen sport. 35m sprints are good for team sports, while athletics + endurance running will naturally involve longer distances. Finally, a good way to commence landing training is with crossover hops and scissor jumps, then later progressing to box jumps. Towards the end of phase 3, all three of these areas can be addressed by returning to training at lower intensities. This is the best way to prepare your knee for your own sport specific demands, as well as providing the social benefits of rejoining your team/training group.
Clearance of phase 3 involves achieving criteria relating to:
Achieving full strength and balance (determined via strength + balance testing)
Completion of agility training program (incorporated into rehab)
Attaining excellent hop performance (determined by single, triple and crossover hop tests)
Phase 4: Return to Sport
The 4th phase is the most individualised, with the demand you face upon returning to play being dependent on your sporting environment. Exercises continue to progress in difficulty from phases 2 and 3, while the aim is to fully integrate into training and practice environments. Once you are training regularly without issue, the long-awaited day is determined based upon objective measures of your physical condition (eg scoring 95+ on Melbourne Return to Sport Score), subjective measures of your own confidence to return to pre-injury sporting intensities, and having an ACL reinjury prevention program prepared.
That final point relates directly to phase 5, which is important not to neglect so that you don’t undo all your hard work!
References
Cooper, R., & Hughes, M. (2018). Melbourne ACL Rehabilitation Guide 2.0 [Ebook]. Melbourne: premax. Retrieved from https://www.melbourneaclguide.com/docs/ACL_Guide.pdf
Filbay, S., & Grindem, H. (2019). Evidence-based recommendations for the management of anterior cruciate ligament (ACL) rupture. Best Practice &Amp; Research Clinical Rheumatology, 33(1), 33-47. doi: 10.1016/j.berh.2019.01.018
Jenkins, S., Guzman, A., Gardner, B., Bryant, S., del Sol, S., McGahan, P., & Chen, J. (2022). Rehabilitation After Anterior Cruciate Ligament Injury: Review of Current Literature and Recommendations. Current Reviews In Musculoskeletal Medicine, 15(3), 170-179. doi: 10.1007/s12178-022-09752-9
van Melick, N., van Cingel, R., Brooijmans, F., Neeter, C., van Tienen, T., Hullegie, W., & Nijhuis-van der Sanden, M. (2016). Evidence-based clinical practice update: practice guidelines for anterior cruciate ligament rehabilitation based on a systematic review and multidisciplinary consensus. British Journal Of Sports Medicine, 50(24), 1506-1515. doi: 10.1136/bjsports-2015-095898