You can't completely prevent a torn ACL, but you can reduce the incidence of non-contact injuries and re-injuries. When another athlete throws his body into yours, causing your knee to buckle and rotate, even the strongest muscles cannot absorb all the force before the torque reaches your ACL. However, many ACL injuries occur in isolation, when an athlete plants and pivots, lands wrong with one leg too far from his body, or puts on the brakes without being in a controlled body position.
With increased participation in adolescent competitive leagues, the incidence rate of these injuries has skyrocketed over the last decade. To combat this, injury prevention programs have popped up everywhere, from large performance centers to your local big box gym. They all prescribe similar exercises, addressing"agility," basic strengthening, and core work. But this is a sensitive population to work with, and many factors are overlooked in the design and implementation of these programs.
The exercises in many of these programs have merit, but the main distinguishing factor of successful programs has to do with how the athlete performs each exercise and how much recovery time is allowed. This depends on who is facilitating the program. Every mechanical component of athletic movement should be addressed before advancing a progression, and it is incredibly important to receive continuous feedback on muscle fatigue to reduce the risk of re-injury.
Many programs also fail to go beyond basic exercises and neglect to address psychological factors, including confidence, distractions on the field (where athletes can't focus directly on the knee), and favoring the unaffected limb. To construct an appropriate injury-prevention program with a return to play (RTP) progression, one must have a complete understanding of the full process from start to finish.
An optimal progression after a torn ACL should be as follows:
INITIAL INJURY->PREHAB->SURGERY->REHAB->RTP PROGRESSION->GAMEPLAY
Unfortunately, many athletes neglect the "prehab" phase. Prehabilitation is done with a physical therapist or athletic trainer, from the point of initial injury through surgery, with the goals of decreasing swelling, increasing or maintaining hamstring mobility (this muscle group often contracts or guards after an ACL tear), and activating the quads, which often shut down and atrophy with an ACL tear and subsequent surgery. The Prehab phase includes rest, ice, compression and elevation (RICE), electrical stimulation for muscle recruitment, manual therapy and mobility techniques.
An athlete's safe return from an ACL injury rests on the quality of his or her surgery. Many orthopedic surgeons perform ACL reconstruction, but there is a wide range of approaches and experience. Although new techniques are on the rise, the current standard for a torn ACL is to use one of three main graft types: cadaver, bone-patella tendon-bone (BPTB), or hamstring. All come with benefits and potential setbacks.
An ACL is harvested from a cadaver and replaces the injured ligament.
- Pros: Less damage to surrounding healthy tissue; no drawbacks from hamstring or patella tendon grafts.
- Cons: Since the graft comes from another body, it may not be compatible with your body and your knee could reject the graft.
Bone-Patella Tendon-Bone (BPTB) Graft
The middle third of your patella tendon is harvested along with bone plugs from your kneecap and tibia to construct your new ACL. The remaining patella tendon is sutured together to heal.
- Pros: Very common and easy to harvest; no knee extension issues.
- Cons: Potential for long-term anterior knee pain and tightness; full knee flexion is a challenge during physical therapy, with occasional longer-term discomfort when kneeling.
A section of your hamstring tendon is removed and put in place of the ACL.
- Pros: No anterior knee issues; no risk of tissue rejection.
- Cons: Sometimes the surgeon will be unable to harvest a suitable graft due to tendon size and must resort to an alternative graft method; potential for hamstring tightness and adhesions during recovery.
Some surgeons favor a specific graft type. Others make individualized recommendations and guide you through the benefits and drawbacks of each. All grafts must be threaded through a tunnel drilled into the knee along a specific axis. The success rate of surgery is highly dependent on tunnel placement and angle, quality of the graft, and additional structures that may have been involved in the injury, like the MCL or meniscus. Do your research before choosing your surgeon and take the necessary steps to make a safe recovery.
The rehabilitation process begins the moment surgery is completed and can last anywhere from 5 to 7 months, depending on various factors: patient compliance; prehab; quality and type of surgery protocol used; and any setbacks during the process. Other structures can be injured with a torn ACL, including the MCL, PCL, menisci and cartilage. If any of these is a factor, it could significantly change the length of the rehab process as well as the approach. For example, an MCL tear may limit extension as the collateral ligaments reach greater tension in extension, while a cartilage or meniscus injury may limit the closed-chain, compressive, forces that can be administered to the knee during exercise.
Rehabilitation is done with a physical therapist (or athletic trainer in collegiate settings). The goal is to provide an optimal environment for the healing process, while addressing the following objectives:
- Inflammatory Phase. Wound healing, reduce edema and swelling, pain control, increase/maintain range of motion, muscle activation, light strengthening above and below the joint, maintain cardio, proprioception.
- Proliferation Phase. Protect the graft as it becomes vascularized, obtain/maintain full range of motion, muscle strengthening around joint, balance/stability, proprioception, functional movement.
- Maturation Phase. Introduce a progression of stresses to the joint to allow for remodeling and strengthening, advanced strengthening, sport-specific progressions, advance cardio, challenging balance and stability, muscle endurance.
Although many PT facilities are chosen for convenience or doctor referral, I highly recommend researching facilities to find a sports-minded PT and a facility with adequate space for sport-specific progressions.
After completing physical therapy, many athletes are cleared and simply return to their sport, some without having run or cut at full speed yet. They are given verbal instructions and are expected to appropriately work their way back up to game speed, assuming their coach also understands what they are going through. This is where the RTP Progression comes in.
The return to play progression bridges the gap between physical therapy and competition by introducing every movement pattern that could be encountered on the field in a controlled environment under the supervision of a healthcare professional. The following concepts can apply to both athletes coming out of physical therapy and healthy athletes looking to stay on the field and win the battle against ACL tears.
ACL RTP Progress Evaluation
Before working with an athlete, it is important to have a thorough understanding of where he or she is in their progression and current risk factors that make them susceptible to re-injury. Many athletes coming out of physical therapy have had an exit assessment before being cleared, including the 4-Hop tests, which look at single-leg plyometric ability, and various functional tests. A complete ACL evaluation should include a history of the process to this point, a functional movement screen, a change of direction assessment, a landing test, and a muscle endurance test, at minimum. I recommend the following:
- FMS Test. The functional movement systems screen consists of 7-movement assessments graded 1 to 3 and 3 provocative tests scored positive or negative for pain. These highlight muscle imbalances side to side in terms of stability vs. mobility.
- Cone Stops. Cone Stops involve 4 cones in the shape of a box. The athlete runs in at various speeds and progresses from linear deceleration to deceleration and pivoting out of the box, to deceleration and higher degrees of rotation and elevated speeds. This progression shows exactly where the athlete's current comfort zone is and where he or she needs to progress. Athletes with an ACL tear should wear their assigned brace to complete this test.
- Depth Jumps. Depth Jumps emphasize any instability on landing due to increased force production required of the muscles and increased speed at which the muscles around the hips must fire. Initially, I have the athlete step off an 8-inch box and observe their mechanics upon landing. We then progress to hopping off a 12-inch box with a jump upon landing if the athlete correctly completes each step along the way.
- Video Analysis. After a dynamic warm-up (which also keys me in to the athlete's movement capabilities), I have athletes perform a sprint at the fastest speed they are comfortable with and analyze their mechanics with slow motion video footage to look at joint angles from head to toe and distinguish any imbalances side to side.
- VersaClimber. Although not all facilities have a VersaClimber, this piece of equipment allows the athlete to push their muscles to fatigue without high impact in a controlled motion. Have the athlete work toward as many feet as they can climb in one minute, observing when they fatigue and seeing if one side fatigues faster than the other, while recording completed feet for a baseline.
Mechanics: Change of Direction, Running Form and Landing
Mechanics should come first when administering an ACL injury prevention or RTP program. Many athletes enter their sport without formal sprint or agility changing, putting themselves at higher risk for injuries. I break change of direction training down into the components acceleration and deceleration, teaching forward lean, knee drive, triple extension, and placed footstrike for acceleration, then emphasize the change from this position to a wider lower stance with the shoulders at the edge of the knees for deceleration. Each turn or change of direction can be broken into a period of acceleration followed by a period of deceleration, finishing with a final bout of acceleration toward your destination. Doing so not only helps put the athlete in optimal position at the right time by giving him control and stability at faster speeds, but will help him change direction faster.
Congruent Running Form
Running form is included under the umbrella of mechanics, but deserves special recommendation for athletes coming out of surgery, as they may be unbalanced side to side, favoring the unaffected limb and toeing off the surgical limb too early before reaching triple extension. Furthermore, athletes required to wear a brace are limited in the heel recovery phase of the stride cycle, which may also contribute to unbalanced form. It is important to identify what the abnormality is stemming from and prescribe appropriate exercises to correct it.
Encourage the athlete to land "back and down," using their muscles as shock absorbers as opposed to landing with stiff or straight legs. Progress to single-leg and rotational landings to simulate game time scenarios.
Reactive Ground Force
Progress landing tactics by adding jump or sprint-out variations on ground contact, encouraging the athlete to produce power as soon as they feel the ground reach their feet. Introduce landing and rotating out as the athlete advances with correct mechanics. Observe fatigue and allow the athlete to recover if you notice instability or valgus collapse (knee coming in) upon landing.
Full-Body Functional Strength Progressions
In PT, the athlete generally focuses on the muscles around the knee, hip, ankle and core in terms of strength progressions. To get an athlete fully prepared for on-the-field experience, it is time to link all the muscles together with exercises that incorporate compound movements and transfer of power from lower body to upper body, such as Dumbbell Squat to Press. Since the hamstrings act as a safeguard, preventing anterior translation of the knee, it is crucial to continue eccentric hamstring strengthening with something like the Nordic hamstring exercise. Single-leg strengthening and glute work are also important in the progression, to make sure the knee remains stable above the foot throughout the exercise. Upper-body pull and push exercises should be incorporated in an individualized approach to each athlete. Athletes without previous knee injuries can also benefit from this strength program.
Athletes should participate in active recovery exercises that increase mobility or improve stability where deficits were found during the FMS test. Exercises, which should be prescribed individually, can include anything from ankle 4-way strengthening and dorsiflexion to postural correction and yoga.
Make sure all systems of input for balance are addressed (eyes, vestibular, somatosensory), while challenging the athlete to adapt to new movement patterns with ladder stepping drills and footwork patterns. Progress from double-leg tandem stances on a firm surface to single-leg, eyes-closed exercises on an unstable surface for balance exercises while increasing the complexity of stepping drills from 2 steps and 4 steps to 3 steps or combinations of these in different directions.
Reactive Agility/Cognitive Agility
Instead of simply having an athlete go through a specific predetermined cone pattern, have him progress to open-ended agility drills where he must react to a verbal or visual cue—after he has shown sound mechanics during pre-planned exercises. Cognitive agility incorporates brain processing in agility drills by making the athlete solve a problem before changing direction. For example, set 4 cones out at a distance, designated 1-4, with a "launch cone" set 10-15 yards in front of the athlete but behind the four destination cones. As the athlete sprints toward the launch cone, call out a simple math equation like "2 minus 1," indicating he must run to the "1" cone. Cognitive agility is best performed after a full agility progression at the end of a workout, forcing the mind to stay engaged. Reactive and cognitive agility both help simulate game time scenarios while encouraging the athlete to make correct decisions and stay in optimal position under pressure.
Power Production/Landing Reaction
By the end of physical therapy, most athletes have only just touched on plyometric drills and are often cleared before progressing to advanced single-leg exercises. The goal of a Return to Play progression is not only to get them back to the field and decrease the risk of re-injury, but to get them back to the athlete they were pre-injury, or better. Healthy athletes looking to reduce their risk of injury can benefit from power production drills and hopping progressions by increasing the rate at which their muscles produce force.
It is common knowledge that women are more susceptible than men to ACL tears, one of the reasons being a slower muscle firing rate, as observed in multiple studies. Plyometric drills target the stretch-shortening cycle to recruit more muscle fibers at a faster rate. The following progression should be taken cautiously for athletes returning from injury, and special note should be made to avoid knee valgus upon ground impact and movement on jumping.
- Ankle Hops
- Squat Jumps
- Box Jumps
- Broad Jumps (safety on landing)
- Tuck Jumps
- Depth Jumps/Forward Bounds
- Single-Leg Ankle Hop and Stick
- Single-Leg Ankle Hops
- Lateral Bounds
- Rotational Jumps
- Single-Leg Landings
- Rotational Single-Leg Hops
- Some crossover between different single-leg and double-leg exercises in this progression
Psychological Return to Play
When an athlete is returning to her sport after a traumatic injury, she often presents with psychological hurdles like fear of planting hard with the surgical leg, imbalanced running mechanics (sometimes psychological/sometimes due to physical limitations), fear of progressing to the next step in a program, anxiety over the length of the return process, or even decreased intensity/aggression in her sport, leading her to play as a different athlete. Often neglected in RTP programs, these factors must be addressed to give an athlete a fighting chance. Upon initial evaluation, I focus on the positives of their situation. They have just spent 5-plus months through grueling rehab and are on their final step, where they finally get to start feeling like an athlete again. Furthermore, I invite them to look at this as an opportunity to fine-tune, sweat the small stuff, and emphasize form and technique that they may not have been able to address prior to the injury.
To help an athlete overcome fear, it is important to allow them to build on their accomplishments by proving to them what they are capable of, making sure they feel they are in safe hands by explaining the process (where they are, where they are headed, and why they might be feeling the way they are), and introducing other athletes to the mix once that have reached the final stages of the program. In addition, it is beneficial to watch game film of the athlete pre-injury to learn their playing style and more appropriately tailor their program.
On the other end of the spectrum, we see the overconfident athlete who sees success early on and literally has to be pried from their stick or ball. For these athletes, it is important to stress that although they have the finish line in sight, they cannot expect to leap and cross it successfully. They've spent 5-plus months getting to where they are now; and although they are at the final stage, it is more important than ever not to rush. I explain the significance of each step and set short-term realistic goals that will get them back on the field safely. In addition, the athlete and parent should be given detailed instructions for what they are able to do outside the program and upon their return.
Another neglected component of injury prevention programs is performance when distractions are present. Sure, the athlete can keep her knee in a good position when she is focusing on it, but what happens when a ball or other players are brought into the drill. My goal for all performance programs is to have the athlete focus on form and technique during training, but focus on the game when on the field. Toward the later stages of a successful injury prevention program, the athlete should be introduced to these external factors at slower speeds at first, observing the ability to maintain proper mechanics before advancing.
In all sports, even non-contact sports, the athlete should be introduced to some form of external force to simulate impact with another player, ball or obstacle on the field. I begin to introduce this with Squat Holds, where the athlete is pushed around in a full squat position and must maintain form. This is progressed to full-body perturbations in a single-leg stance and mid-air contact, cueing a stable landing. These types of drills are used by professional athletes in the MLS and through the FIFA 11+ injury prevention program, which has been proven to decrease injury rates. Final stages include falling techniques on a crash mat, where the athlete must jump in the air, accept contact and actually fall safely, evenly distributing force across the body so that one joint or ligament isn't taxed by the impact.
Muscle Endurance/Performance fatigue
Injuries tend to occur when the athlete experiences fatigue and is no longer able to maintain form. A successful injury prevention program should focus on helping the athlete remain stable from the start of the game to the final buzzer. Muscle endurance should be addressed within their strength program with reps in a 15-plus range or with specialty equipment like the VersaClimber, which can provide resistance to a climbing-based pattern. The musclesmustbe pushed to fatigue, but adequate recovery time is vital due to their increased risk of injury in this state. Consider performing controlled strength training after turf/movement work to avoid putting the athlete in adverse conditions. Toward the end of the program, an athlete's functional performance should be taxed in order to gauge how long she can perform before experiencing muscle fatigue or showing diminished body control. When the athlete is ready, consider shadowing drills, where she has to react and follow another athlete at controlled speed and time intervals, assessing for muscle fatigue every step of the way.
Cardio endurance should be addressed to keep the athlete's level of awareness up on the field and remove as many factors as possible that could sacrifice performance or mechanics. Look at the athlete's sport and plan conditioning drills that work around the work-to-rest ratios of his position. This allows him to work at an elevated heart rate longer, while working to recover faster, bringing him closer to what he will experience out on the field.
Before exiting the program and returning fully to their sport, athletes are run through a complete performance evaluation, or combine, assessing all areas of performance, including speed, power, agility and endurance. This is the same battery of tests our healthy athletes perform, and we can compare the returning athlete to normative data to see exactly where she stacks up against others of her age and gender. This will help highlight any remaining target areas while boosting the confidence behind their return, showing numerically that they are ready for competition. Additional video analysis tests may be used to snapshot a before-and-after of improved mechanics for sprinting, acceleration, deceleration and landing.
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