Reaching month 9 post-op in ACL rehabilitation is a big milestone and here's why...
After 9 months post-op the risk of ACL failure and re-injury decreases and the likelihood of safe return to sport increases. Although it is common to see professional athletes return to sport earlier than 9 months, it is not as common in high school or collegiate athletes.
Ardern et al produced a meta-analysis and systematic review on return to play considerations after ACL surgery. There were 5770 who participated in the study and reported outcomes through 3-4 years
post-op. Here is what the data showed. - About 90% achieved normal knee function in regards to strength and ligament laxity
- 63% returned to their pre-injury level of participation
- 44% returned to competitive sport competition
This data suggests that 1/3 to 1/2 of all athletes who undergo ACL reconstruction never return to their previous level of sports competition! As time goes on we are learning more and more about why certain athletes achieve a solid return to sport and why others fall short.
Reasons For A Low Return To Competitive Sport
There are two main theories as to why a large number of athletes fail to return to full sports participation after ACL reconstruction.
1. Fear of injury
2. Absence of a robust neuromuscular return to play progression in rehab
As mentioned in previous ACL posts, fear can be a devastating force that limits your progression in rehab and leaves you on the sidelines. Sustaining an ACL tear is a traumatic and painful experience and it leaves an imprint on your memory. Returning to the "scene of the crime" is humbling and takes some gusto to overcome.
Starting early in rehab, month 3 or 4 even, you need to start addressing your fear of injury and your fear of returning to the sport where you sustained your injury. Often, we avoid painful situations since we are programmed to protect ourselves against any additional episodes of pain. ACL rehab however requires you to address that fear head on.
Many post-op athletes have difficulty initiating sport based neuromuscular training, especially single leg drills, due to fear of potential pain or injury. Working through this fear is essential as playing a high level sport demands fast subconscious action without thought or injury risk. Typically, an athlete can start single leg training in months 4-6 and these drills can progress to game speed by month 9.
Again, sport based variable practice is key here. Some examples of training during month 9 for return to sport include:
1. Sprint to deceleration while catching/kicking a ball
2. Sprint to lateral shuffle while catching a ball
3. Sprint to pull up jump shot
4. Jump off 1 foot while your therapist pushes in the air with a ball requiring you land softly and with good form
5. Agility hurdles while playing catch (agility ladder works too)
These are just a few examples of adding complexity and specificity in training. Also, the varied throwing, catching, jumping, change of direction, and perturbation is what trains your knee to be comfortable and confident in sports based game speed situations.
Specific Neuromuscular Training
In month 9 of ACL rehabilitation, it is important to train the same lower extremity movement mechanics learned in previous months but at a higher intensity and speed.
Multiple studies have found altered loading and long-term gait deviations after ACL reconstruction. In particular, it has been noted that athletes have difficulty normalizing impact forces with running and jumping. This has been tied to decreased hip flexion range of motion and decreased knee flexion range of motion during sports based activities. Increased impact forces and decreased lower extremity joint flexion can be collectively termed "poor shock absorption".
Even after multiple years post-op ACL reconstruction, gait deviations and higher impact loads remain. It is important to address these issues early in the rehab process, months 6-10, to assist with long term knee health and function.
Exercises like the drop jump and depth jump will improving shock absorption. At my sports performance clinic, and other ACL specialty centers in the country, athletes use biofeedback from a force plate to see and in real-time correct their impact forces. Performing a drop jump onto a force plate necessitates the usage of a "hip strategy" versus "knee strategy" to lower impact forces. This same movement pattern is then habituated with jumping drills and single leg running drills. Additionally, exercises like landing from a box jump on one leg in front of a mirror helps to learn proper lower extremity control. Knee inward collapse (valgus) is linked to ACL tears and therefore the rehab process must address the control of this movement with high level training. Video feedback is essential during this phase as you will be cutting and decelerating and high frame rate video (100 FPS) is necessary to pick up knee alignment.
Be sure video is incorporated into your month 9 ACL rehabilitation program to assist in your motor learning.
ACL Rehabilitation Return To Sport Testing: Part 2
Back in ACL rehab month 6, I advised on an initial return to sport test. The reason for the initial testing was to document where your strength and weaknesses were in terms of strength and motor control. The testing at month 6 sets the stage for rehab progression in months 6-9.
Typically, I perform another return to sport test at 9 months post-op. This testing is more robust in terms of speed and power. All the testing previously performed will now be done at near game speed (assuming your PT has cleared you for that level of testing based on your overall progress and mental readiness).
In addition to tests such as the drop jump, lateral shuffle, and triple hop, it is advised to also perform a single leg max jump, crossover hop, and a running analysis. The running analysis serves to pinpoint any issues with shock absorption or power generation. Running is a part of every sport and therefore should be addressed.
Grading of the test again is based on hip control, knee control, trunk control, pelvis control, and shock absorption. These are key biomechanics variables to powerful controlled sport motion.
Here again, if you don't have access to a human performance center be sure to ask your PT to record you with high speed video doing sport based movements so at least you have some data on your movement quality and skill. For more information on the return to sport testing we do here at Competitive EDGE Physical Therapy, please check out this link.
Kevin Vandi, DPT, OCS, CSCS
Dr. Vandi is the founder of Competitive EDGE Physical Therapy — with his background in physical therapy, orthopedics, and biomechanics, he is a highly educated, compassionate specialist. Using state-of-the-art motion analysis technology and data-driven methodologies, Kevin has assisted a wide range of clients, from post-surgery patients to youth and professional athletes. When he isn’t busy working or reading research, he spends his time with his wife Chrissy and their five wonderful children, often enjoying the outdoors and staying committed to an active lifestyle.