lets have a chat about this ACL problem? Can we do anything about it?
ACL injuries are a very important topic in sports related medicine at the moment and for good reason. The potential risk for ACL injuries is very high and continues to rise in sports like football and basketball where sudden changes in velocity are required ( Joseph et al 2013 ). Interestingly, on average 30 percent of the ACL injuries are caused from impact while the remaining 70 percent have no traumatic origin( Griffin 2000 ). In America alone there are 100,000 operations a year for the injury.( NCH 1996 ) the likelihood of re-occurrence is high with rates as much as 30 percent within the first 12 months! (AOSSM 2012)
These findings bring up some really serious questions on the topic of prevention and how have so many ACL tears even occurred in the first place if they are of mechanical origin? Can they not be prevented? Unfortunately there is still currently a lack of understanding about modifiable risk factors ( Joesph et al 2013 ) and some researchers even conclude a critical evaluation should be carried out into the current treatment and prevention methods ( Paterno 2013 )
I would like to discuss these topics further and hypothesize whether a new treatment approach is needed. to understand how we might be able to develop and improve treatment we need to why an ACL injury has occurred in the first place.
Non contact ACL injuries are reported to occur for a few different reasons. A dynamic valgus experienced during sport is one of the primary reasons an ACL may undergo stress, It usually occurs in Athletes who require quick abrupt changes in direction by cutting and shifting their feet. A dynamic valgus involves femoral adduction, an eversion of the ankle and an abduction or medial displacement at the knee.( Hewett 2005) Movement in these extremity joints can produce an opposing internal rotation at the femur and external rotation at the fibula and put the knee joint and acl in a compromised position. Athletes will regularly experience some sort of dynamic valgus throughout the game as it is completely inevitable but if the ground reaction force passing through the knee gets too great for the ligament to handle during this compromised position the ACL may partially tear or rupture completely.( Andrews 1985)
Now the question is how do we minimize the ground reaction force through the knee? And how in the hell do we prevent an injury If malalignment is an inevitable outcome during large changes in direction?
Before we get into that let’s talk about Stability. Stability is a concept that many are probably familiar with. In short we have two stabilizing systems. Our first being active stabilizers. (muscles and soft tissue), Muscles and soft tissue transfer load through a relative degree of controlled contraction. Next up we have the Passive stabilizers (ligaments and cartilage) that utilize the surfaces of their articulations and their positions to transfer load.( Comerford 2001 ) Remember that if the active stabilizers are insufficient at their job the passive system will have to take up the work load . This compensation is one of reasons the ACL can get injured. This process is called ligament dominance wherby an insufficient ground reaction force is absorbed by the muscles so it must be transferred on to the ligaments and is a primary risk factor in ACL injury a we’ve discussed already ( Hewett 2010 )
Treatment: Considering the chance of re-injury and the high percentage of non traumatic injury. It is important to look at re-evaluating treatment in the literature. While a lot of standard treatment has so far focused on rehabilitation of the reconstructed knee with the main goal of improved strength and mobility, and some incorporated balance.( UCSF 2010 ) These protocols may not have as much carry over as conventionally thought ( Risberg 2007 ). Strength in the knee is an important part of the overall rehabilitation process especially if muscles have atrophied since the joint was immobilized after the tear but may not reduce risk as effectively as other therapeutic approaches.(Herman et al 2008 ) What seems more promising now is an integrated neuromuscular and biomechanical approach. ( Sugimoto 2012 ) .This is my brief attempt at reviewing over some of the literature regarding some new progressions in the treatment of ACL injuries.
Biomechanically we can reduce the strain on the ACL through better and more efficient positioning of the knee and Neuromuscularly we can re-imprint better motor control to reduce faulty positions from arising. Both of these approaches go hand in hand with one another.
To begin on the Biomechanical front. Preventing dynamic knee valgus from occurring during sport in the first place involves knowing what a safer position is for starters. The correct joint position is the knee tracking over the toes and the femur in alignment with the tibia as seen in the picture described below. Contracting the gluteus maximi is important here and recent studies have even demonstrated its stabilizing effect on the lateral portion of the knee via its fascial connection with the iliotibial band and fascia lata. ( Gottschack 1989 ) on top of this, active contraction of the glutes will inhibit adduction or inward collapse of the knee. Focusing on activating all muscles around the leg is another key component to take the load off the passive(ligamentous) system. Strength training such as banded squats and side stepping excercises are encouraged within this active rehabilitation as well.( Tsaklis 2002 ) All of these considerations will increase the static and active stability at the knee joint, a mirror may be used to assist in this proprioceptive orientated training.
The very important factor of motor control needs to be addressed as well. It is somewhat brushed over in the topic of physical therapy rehabilitation but is still one large piece of the puzzle. Although we have stabilized the knee efficiently with exercise and a knowledge of good positioning, this being the sole goal of our rehabilitation program will yield useless unless we focus on the dynamic positioning of the knee joint during sport, we must not forget the same rules do not apply during dynamic movements compared to active ones ( where we consciously control our knee) . Dynamic movements could range from dribbling in lacrosse or tricking in football , any movement of the body involved in competition level sport. Remember that when you are playing sport you are unlikely to maintain or reproduce the stable knee position you practised in the mirror with your exercise bands. These exercises are a stepping stone in the right direction but since the stabilisation of peripheral joints in a load specific environment is unconscious and dictated by the nervous system.( Bryan et al. 2002 ) Then, Adequate training needs to be completed for joint positioning to be imprinted on the CNS till it becomes an unconscious movement pattern( Plautz et al 2000)( Jensen et al 2005). This means environmental specific training and repeated high volume will be the only way to ensure real carry over to the dynamic constraints of sport. It’s going to take a lot of practise but is the only way to ensure correct and stable joint positioning becomes an unconscious behaviour and thus a protective one. This further progression from standard strength training could involve active shifting and cutting drills with an emphasis in proper knee positioning. If motor control isn’t a goal in the rehabilitative program, inadequate programming of the central nervous system could occur and faulty positions will go on and on and on. It could be one of the reasons why secondary ACL tears are so common with associated neuromuscular deficits.( Stasi 2013 )
There are other factors that contribute to the likelihood of an ACL injury that I will not go into great depth due to the length of the article but will leave a short brief comment about them referencing the appropriate literature.
Trunk dysfunction: It may not necessarily be the problem that the core is weak. But certain positions of the trunk relative to the lower extremities during functional changes in direction has shown to be a risk factor to ACL injuries. ( Zazulak et al. 2007 )
Leg dominance: If a particular leg is more dominant than another, it is likely to be more prone to injury. The dominant leg could be considered the planted leg or the “jumping leg”. ACL injuries often occur where all of the weight is shifted onto one of the limbs. The greater use of a limb will statistically provide a greater chance of ACL injury.
Quadriceps dominance: this neuromuscular dysfunction occurs more often in women than men, the ratio of strength in the quadriceps than that of the posterior thigh is skewed. The quadricep dominance will lead to altered loading patterns and will be more prone to bring the knee into extension and place a larger deal of anterior sheer stress on the ACL ( Hewett et al 2005 )
Landing patterns: Landing can take place with either the forefoot or the heel. Because of the excessive anterior forces associated with knee over extension, heel striking is contraindicated and has been a repetitively reported mechanism for injury.( Loyd 2007) Furthermore electromyography suggest that the equalizing effect the posterior hamstrings may have on limiting knee extension are dampened when heel striking. Its just another reason to quit locking those knees.( Draganich )
It is my opinion other Prior muscular imbalances like excessive tibial rotation or foot pronation (duck feet) can increase the risk of valgus during functional movement and another mechanical flaw to consider.
That’s all for today people hope you enjoyed that!!!
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Caolan here. Im a curious man to say the least and as an enthusiastic enrolling physiotherapy student. I have felt the need to share my thoughts and conclusions on the topic that is pain. Its something that will effect us all. Above all its very mysterious, misunderstood and complicated one and Im here to figure out more.