When a person experiences an ACL injury, surgery is usually indicated. If a person can get their strength improved, decrease swelling and achieve full knee extension prior to surgery then they will be more apt to be successful post-surgery. The recovery post-ACL surgery is extensive, progressive in nature, and will depend on the goals of the person or athlete and what they intend to return to in terms of certain activities or sports. Usually, one can expect at least a year of rehabilitation post surgery. With that being said, for every month of continued rehabilitation after the six-month mark after surgery, the risk of re-tearing the ACL reduces by 24%.
For a successful recovery, one needs both static and dynamic stability (static means while still and dynamic meaning during movement), normal knee range of motion, and proper strength and stability in the knee, hip and foot (above and below the knee) as well as core. The person needs to be symmetrical in both legs with jumping and landing tasks (double leg and single leg) and return to full-capacity sport-specific training. Often, people are notedly still unconsciously unloading their involved leg during jumping tasks even a year after surgery.
The healing time of the actual graft can depend as well. If it is an autograft (from the person’s own body) then the bone-tendon-bone graft will take six to 10 months to heal, and with hamstring tendons specifically being eight to 12 months to heal. If it is an allograft (from a cadaver) then it is expected to take 10-12 months and beyond. If there is also noted bone bruising, meniscal damage or other issues like prolonged effusion then this may extend the healing time. The graft is most vulnerable at six weeks post-op, but can be for up to 12 weeks as well.
There are certain phases of rehabilitation that one will proceed through post-ACL surgery. This may differ depending on the particular person, but relatively speaking these phases are based on time-lines from surgery. If there is low motivation, high pain level, or apprehension and fear then this may play a part in the recovery process and delay the progress through the phases.
Phase one of rehabilitation is considered to be the first two weeks post-ACL repair operation. The goal of this phase is to gain full knee extension (straightening) as soon as possible, but it is important to not hyperextend the knee. During this phase, one will progress the flexion (bending) range of motion as well and needs to minimize the swelling of the knee. Activation of the quadricep (thigh) muscle is very important as well, and returning to normal walking with no limp is a key. One should have a smooth walking pattern, with normal heel strike to toe push-off, aka “heel to toe” gait.
Some general treatment ideas during this phase for range of motion include heel slides, knee extension prone hangs, progressive core, hip, quad, and hamstring strengthening like leg raises in all four directions. Weight shifting and single leg balance exercises are also important as well as the stationary bicycle for range of motion of the knee.
Phase two of rehabilitation is two to four weeks post operative. The goals again are to obtain full knee extension, progress the knee flexion range of motion, get back to walking properly with no crutches and no limp noted. One should continue to manage the swelling, as there can often still be some swelling at this point and as one continues to progress with more weight-bearing through the exercises. There should be a focus of strengthening the quadricep muscle in order to be able to do straight leg raises with no “extensor lag,” meaning the person is able to keep the knee extended straight and the quadricep activated while lifting the leg.
Treatment ideas in this phase involve progressive quadricep strengthening, such as mini squats modified to 0-40*, and standing terminal knee extension (pressing the leg straight back against a resistance band in order to achieve quadricep strength while bearing weight). The core and hip strength should be a focus, as well as adding resistance to the stationary bicycle as able. The hamstring muscles are key muscles to be strengthening as well, as this muscle helps to stabilize the knee and supports the ACL based on its attachment sites.
The next phase is four to six weeks post operative. Full active range of motion should be achieved at this point, equal to the other leg. There should be a normal gait pattern, and one should be able to go up a step without compensation. There can begin to be open chain (meaning the foot is free and not in contact with anything) long arc quadricep exercises performed at 90-45 degrees, however you do not want to load the knee joint with an “open chain” position until four to five months due to potential excessive strain on the graft. Stairs and step ups are a focus (with proper knee stability), the leg press machine, wall sits, hamstring curls and bridge exercises, core such as multidirectional planks, squat progressions, walking backward on the treadmill, and standing on unstable surfaces for balance and proprioception.
At six to twelve weeks, one should be able to safely complete initial return to sport testing as long as the proper knee stability has been achieved. This testing involves balance and muscle testing, to include hip strength exercises to fatigue, single leg balance testing and stand and reach testing. Core stability testing such as timed plank hold, timed side plank hold, and single leg bridge for repetition to failure. The stairs both up and down should be noted normal and no pain, as well as initial hopping progressions can be initiated at about ten weeks (again, as long as the proper strength and form are achieved).
During this phase of rehabilitation, some exercise ideas are single leg squats, double-leg jump and land form training, reverse treadmill walking with an incline, increased aerobic exercise such as the stationary bike (no toe clips until about four months post-operative) and elliptical trainer at eight weeks. Lunges can also be introduced with proper cueing for exact knee positioning and form.
At 12-16 weeks post operative, the person should be progressing strength and endurance, and be able to land with proper technique as well as perform double leg jumping with triple extension achieved (extension of hips, knees, and ankles). Treatment ideas are to progress squats, jumping from two to one foot up to a box, lateral jumping (no diagonals or zig zags yet), controlled sports-specific movements at a controlled rate such as chest pass in basketball, single leg stance on foam surface with kicking a ball for soccer players, etc. Diagonal lunges can be initiated, and a “return to running” program can begin (if it is an allograft or revision then running should not be initiated until 16 weeks).
At four to six months after surgery, one should complete phase two return to sport testing. This includes muscle endurance and power testing with the star excursion balance test and single leg squats for endurance. By the end of six months, the person should be progressed through phase three sport testing and have at least 80% equal scores on the involved leg versus the uninvolved leg on the “hop test.” The hop test consists of four tests: single leg hop for distance, triple hop for distance, triple crossover hop (over a line) for distance, and a six-meter hop for time. Each leg is tested and the values compared involved to uninvolved leg, and a percentage calculated.
This phase should also include a progression of jumping (now diagonals and zig zags added), shuffling, carioca, figure eight running drills, multi-directional lunges, jumping off a box to soft landing with two feet and progressing to one foot. This person can begin a consistent running program, although should not run on back to back days. Cutting and sprinting drills such as t-drill, hop and stop, cone drills, and change of direction training can be added. It is important to begin working on performance through fatigue, such as step downs at high speed, quick squat jumps, and the agility ladder. The plyometric and agility drills should be performed no more than three days a week in order to allow for recovery time and proper form.
By six months post operative, the goal is to complete the full return to sports testing with proper power. Any limitations found should be addressed fully, and the goal is to return to prior level of function and activity by 12 months. The cutting and change of directions related to that person’s particular sport should now be performed at full speed and they should achieve at least 95%-100% of equal values on the hop test. The person should be tested at the end of the session, after high level activities and strength has been performed in order to reach fatigue. This is to achieve the most “game-like” environment and simulated situations for training to return to their sport. Some examples of exercises in this phase are grapevine, sprinting, shuffling with change of directions, all at full speed.
Again, after an ACL injury and surgical repair of this ligament it is imperative that one completes proper rehabilitation in order to return to previous level of functioning and decrease the risk of a re-tear. The person should have proper guidance and cueing from a professional while progressing through their rehabilitation, in order to ensure proper form and technique so as not to develop poor movement patterns or develop bad habits. ACL recovery may be extensive, but many athletes are successful in returning to their sport and make a full recovery. The key is to work hard, consistently, and listen to the physical therapist in order to return safely.
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