Mechanics of Prevention and Rehabilitation
The anterior cruciate ligament (ACL) is an important ligament of the knee in regards to stabilization (Friedberg, 2013). The function of the ACL is to resist anterior movement and medial rotation of the tibia in relation to the femur (Markolf, Mensch, & Amstutz, 1976). It is the most common injury of the knee and is frequently injured in non-contact; high impact sports injuries such as, skiers, gymnasts, football, and soccer players, where there is quick movement, and changing of position of the feet. Treatment of ACL tears may require surgery or may be treated conservatively in the case of partial tears, regardless a rehabilitation program needs to be created to increase the range of motion of the knee and to increase stability of the knee.
While the approach to ACL injury rehabilitation is constantly changing, there are a few principal methods of treatment that have consistently shown to be of great importance (van Grinsven, van Cingel, Holla, & van Loon, 2010). Rehabilitation can be broken up into four phases; phase one encompasses week one post operatively, phase two includes weeks 2-9, phase 3 includes weeks 9-16, and finally phase 4 includes weeks 16-22. The first step in rehabilitation occurs right after ACL reconstruction, first week postoperatively, and involves regaining full range of motion, especially in extension (Friedberg, 2013). Aggressive control of swelling and pain can aid in achieving full range of motion. Immediate recovery of the range of motion stimulates homeostasis of the cartilage and prevents pattelofemoral problems (van Grinsven, van Cingel, Holla, & van Loon, 2010). . If full range of motion is not achieved there is an increased risk for the development of osteoarthritis in the injured knee (Shelbourne, Urch, Freeman, Gray, 2012).
Closed kinetic chain exercises should be initiated first (Wright, Preston, Fleming, Amendola, Andrish, Bergfeld, Dunn, Kaeding, Kuhn, Marx, McCarty, Parker, Spindler, Wolcott, Wolf, & Williams, 2008). These exercises require the foot to be fixed in space and not move; the foot remains in constant contact with the floor or the base of a machine; examples of closed kinetic chain exercise are squats, lunges, and deadlifts, the purpose of these exercises is to strengthen the quadriceps, hamstrings, and hip flexors.
Closed kinetic chain exercises have been justified in early rehabilitation because they: 1. Reduce anterior forces that act on the tibia relative to the femur; 2. Increase co-contraction of the hamstrings; 3. Increase tibiofemoral compressive forces; 4. Mimic functional activities; and 5. Decrease the incidence of patellofemoral complications (Beynnon & Fleming, 1998). The addition of open kinetic chain exercises early on is controversial, as these exercises seem to increase strain on the new graft. Evidence suggests that open kinetic chain exercises, which are those exercises where the foot is not fixed, such as leg extension and leg curls, can be initiated 6 weeks post operatively safely (Mikkelsen, Werner, and Erikkson, 2000) (Wright et al., 2008).
Full weight bearing with a normal gait pattern should be achieved within the first 10 days postoperatively; doing this prevents patellofemoral pain, increases quadriceps function, and has no effect on the stability of the knee joint (van Grinsven, van Cingel, Holla, & van Loon, 2009). A decrease in range of motion, pain, swelling, and weakness of the quadriceps are the most common reasons that an abnormal gait develops in patients (Gale & Richmond, 2006) (Potter, 2006).
In the following weeks, week 2-9 postoperatively, exercises that increase balance, proprioception, and increase core strength should be added into the rehabilitation routine. During this time the stability and strength of the graft is not at its optimal level (Beynnon, Johnson, Abate, Fleming, & Nichols, 2005) (Lahav & Burks, 2005). Exercises that increase the quadriceps and hamstring strength by isometric isotonic and isokinetic mechanisms should be used because the do not cause damage to the graft. Isokinetic exercises are advised where the appropriate equipment is available for use (McCarty & Bach, 2005) (Cascio, Culp, & Cosgarea, 2004); these types of exercises provide resistance to a limb that is constantly in motion, an example is the use of a stationary bike. Quadriceps atrophy, gait problems, and decreased range of motion after week 5 postoperatively, can lead to quadriceps weakness that is persistent after 6 months (Potter, 2006).
Proprioception may be lost in patients with ACL injuries, and neuromuscular training is important to regain full functional recovery and prevent secondary complications like re – rupture (Risberg, Lewek, & Snyder – Mackler, 2004) (Trees, Howe, Dixon, & White, 2005). The purpose of neuromuscular training is to teach the body better habits for knee stability, for example during jumping, landing, and pivoting. Rehabilitation programs include balance exercises, dynamic joint stability exercises, jump training, agility drills, and in case the patient is an athlete, sport specific exercises (Risberg, Mørk, Jenssen, & Holm, 2001).
Specific exercises for this point in time include, walking on a treadmill, cycling on a stationary bike and swimming starting at week 3, walking on a stair machine by week 4 postoperatively, and outdoor bike riding by week 8 postoperatively (Risberg, Lewek, & Snyder – Mackler, 2004) (Risberg, Mørk, Jenssen, & Holm, 2001) (Wilk, Reinold, Hooks, 2003).
The final phase of rehabilitation encompasses weeks 16- 22 postoperatively, and the main goal is to maximize endurance and the strength of the knee stabilizing muscles. Other important aspects of rehabilitation include optimization of neuromuscular control and agility training. Sport specific agility training is important to improve arthrokinetic reflexes, and may prevent new trauma during competition (Cascio, Culp, & Cosgarea, 2004).
Reduction of pain, swelling, and inflammation, as well as regaining full range of motion, strength and neuromuscular exercises, are important goals and have advantages for improving the stability of the joint overall. With the proper rehabilitation program, and the desire to get better, people and especially athletes with ACL injuries and subsequent reconstruction can have a very good quality of life.
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