The anterior cruciate ligament (ACL) is, “a ligament in the knee that crosses from the underside of the thigh bone to the top of the shin bone and helps stabilize the knee. Injuries to this ligament can occur in a number of situations, including sports, and can be quite serious.” (Sunnybrook Research Institute, 2016). Individuals with ACL injuries can experience swelling and reduced stability in the knee and often require extensive rehabilitation and surgery to repair the ligament. The emphasis of this paper is to determine if it would be possible for a muscle, or group of muscles, to function at the same level after the ACL has gone through reconstruction and rehabilitation.
Many studies have been conducted to determine whether the behavior and function of muscles, after ACL reconstruction and rehabilitation, improve or weaken over time; that is, can these muscles return back to their original functionality after surgery or are they weakened? While there are various explanations for how and why the behavior and function of muscles are affected after ACL surgery, the following paper will focus on the following key themes:
1. Functioning of the quadriceps muscle group;
2. Muscle function and gait patterns; and
3. Finally the benefits of specific ACL reconstruction grafts
Reviewing these key topics will help provide a better understanding of which ACL reconstruction grafts are most beneficial, the maximum functioning capacity of the muscles affected, how the functionality of quadriceps and gait patterns are affected after ACL surgery, and ultimately, how an individual is limited in everyday physical activities.
Functioning of the Quadriceps Muscle
To begin, one of the main themes presented in literature pertains to the functioning of the quadriceps muscle group after the ACL has gone through reconstruction and rehabilitation. With my basic understanding, and prior knowledge of kinesiology and physical education, the quadriceps muscle group is located on the anterior side of the thigh and consists of four muscles in its group.
Many studies show that the quadriceps muscle group weakens after ACL reconstruction and rehabilitation. For example in a 2014 study by Hart, M., Kuenze, C., Riduch, D., and Ingersoll, C., all individuals who had gone through ACL reconstruction, displayed, “evidence of quadriceps dysfunction” (Hart et al., 2014). Furthermore in a 2013 study, patients revealed failure in the quadriceps muscle activation (Kuenze, C. et al, 2013). As such, it can be argued that “muscle weakness is a risk factor… after ACL injury and reconstruction… caused by changes in the quadriceps” (Lindström, M., Strandberg, S., Wredmark, T., Felländer-Tsai, L., and Henriksson, M., 2013). This was the outcome after numerous clinical and functional tests conducted by Lindstrom, M et al.
The above referenced studies all conducted various clinical and functional testing to determine how well muscles function after the ACL surgery. For example, Hard et al., utilized the Hoffman Reflex test, which is a measurement that can be used to “assess [the] response of the nervous system to various neurologic conditions, musculoskeletal injuries application of therapeutic modalities pain, exercise training and performance of motor tasks” (Hart et al., 2004). Kuenze et al, evaluated the quadriceps’ central activation ratio (CAR), which is a measurement of an individual’s “ability to volitionally activate the quadriceps, differentiating weakness from impaired activation…The strength obtained with voluntary contraction is compared to the strength obtained with the electrically elicited contraction and expressed as a ratio.” (Lynch, A., Logerstedt, D., Axe, M., and Snyder-Mackler, L., 2012). Finally, Lindström et al., performed functional tests such as the hop test, which has been “described and subsequently been termed reliable and valid for ACL reconstruction patients” (Lindström et al., 2013). The results of these tests demonstrated that the functioning capacity of the quadriceps muscle group can be heavily affected in patients who have undergone ACL reconstruction and rehabilitation, as compared to individuals who have not.
Therefore, based on the literature reviewed, it can be argued that an individual’s capacity to function in everyday physical activities can become limited if they have undergone ACL surgery. As such, various recommendations have been made to help the functioning of the quadriceps muscle group in post-ACL surgery patients. For example, it has been suggested that recovery programs use open kinetic chain exercises for the quadriceps, as it can result in “significantly greater quadriceps strength” (Tagesson, S., Öberg, B., Good, L., and Kvist, J., 2008). However, it is important to note that although the strength may increase, it may not be better than the force displayed by the quadriceps before the ACL reconstruction.
Thus, when evaluating whether or not the quadriceps muscle improves or weakens post-ACL surgery, literature demonstrates a correlation between individuals that have undergone ACL reconstruction and those who have experienced issues with their quadriceps muscles. That is, quadriceps muscles would not be able function at the same level as they did before ACL reconstruction/surgery and as a result, their functionality would be limited when performing physical exercises and/or doing everyday activities, such as walking for moderate periods of time or walking up a set of stairs. Nevertheless, with certain exercises, the functioning capacity of the quadriceps muscle can be slightly improved, thus allowing an individual to perform tasks with slightly less limitations.
Muscle Function and Gait Patterns
The second theme this literature review analyzed was muscle function and gait patterns post ACL reconstruction and rehabilitation; that is, if and how gait is modified as a result of the ACL reconstruction. With my prior knowledge in kinesiology and physical education, gait is the way an individual walks, jogs, or runs and can be measured in many different ways. According to Webster, K., Wittwer, E., O’Brian, O., and Feller, J., (2005), it is typically done by the analysis of an individual’s body structure in both the sagittal and coronal plane. Literature suggests that, gait patterns are affected in individuals who have had ACL reconstruction. For example, in Webster, K., et al., study patients who were examined were individuals who had ACL surgery/reconstruction and had participated in some sort of rehabilitation program. The study included analyzing subjects who had undergone ACL surgery with “either… a patellar-tendon graft or a hamstring-tendon graft” (Webster et al., 2005). In other literature, such as in the findings of Fisher, N., White, S., Yack, H., Smolinski, R., and Pendergast, D., (1997), individuals who needed ACL reconstruction were those who had osteoarthritis. These observations led to the determination that an individual’s walking manner, or gait, could change significantly after the ACL has undergone reconstruction.
There were various procedures used to analyze gait in the individuals who had ACL surgery, such as the use of a three-dimensional motion analysis system, which is a procedure used to accurately track the movement of an individual, using reflective markers and six (6) infrared cameras (Webster et al., 2005). The results from this testing showed that, “there are graft specific differences in knee biomechanics during walking after ACL reconstruction” (Ibid, 2005). For example, there was “a reduction in the external knee flexion moment at midstance…in the group of patients with patellar tendon grafts, whereas a reduction in the external knee extension moment at terminal stance…in the group of patients with hamstring tendon grafts” (Ibid, 2005). Webster et al., notes that these results are consistent with other studies and that it supports the theme that gait is modified after ACL reconstruction.
Another method used to assess gait after ACL surgery was to the observe an individual’s walking pattern before and after quantitative progressive exercise rehabilitation (Fisher et al., 1997). The results of this study found that gait was significantly different in those who had undergone quantitative progressive exercise rehabilitation programs. For example, “the initial contraction velocities were significantly less” in knee flexion and extension (Ibid, 1997). In contrast to those who had undergone quantitative progressive exercise rehabilitation, gait patterns in the affected individuals were changed.
As such, based on the above findings, gait can be heavily affected in individuals who have had their ACL repaired. The motion of walking relies significantly on the flexion and extension of our knees. The activation of the quadriceps allow for knee flexion which results in the movement of the leg segment in the direction of movement, that is required during gait (Hart et al., 2014). If an individuals quadriceps muscles cannot function, or activate properly, it can, and eventually will, result in a change in walking patterns, either slightly or significantly, therefore impacting the way an individual performs everyday physical activities.
Benefits of Specific ACL Remodeling Grafts
Finally, the last theme observed in literature was regarding the benefits of specific ACL remodeling grafts to an individual who has undergone ACL reconstruction. As stated previously, by the studies of Hart et al., 2014, Webster et al., 2005, and Fisher et al., 1997, an individual who has undergone ACL surgery is more likely to have poor quadriceps muscle function and activation, thus changing the gait of walking patterns of affected individuals. In the analysis provided by Webster et al., evidence showed that the type of graft used during ACL surgery could change the gait patterns of affected individuals.
Earlier studies have noted that the graft type is an important factor when observing individuals who have undergone ACL reconstruction and this is consistent with the findings of, Ageberg, E., Roos, H., Silbernagel, K., Thomeé, R., and Roos, E., (2009). In the study, methodologies included the incorporation of individuals who had ACL surgery, specifically, those who had ACL reconstructed with “PT [patellar-tendon] graft and… with HT [hamstring-tendon] graft” (Ageberg et al., 2009). To understand which graft type is superior, tests such as using exercise machines for knee flexion and extension were crucial in the experiments of Ageberg et al., 2009. This testing contributed to the better understanding of how much power was produced by the quadriceps muscle group. The results of their tests showed that, individuals with the “HT grafts… had 15% lower hamstring muscle power… than the PT graft group” (Ageberg et al., 2009). It was also noted, that there was no difference in the strength of the quadriceps muscles regardless of whether a hamstring-tendon graft or a patellar-tendon graft was used. However, there was evidence that showed that a patellar-tendon graft is more suitable and recommended for ACL reconstruction because the “…difference between the injured and uninjured legs was greater in the HT group” (Ibid, 2009). This resulted in the confirmation that the PT graft was more useful due to its decreased variance between an injured and uninjured leg. Therefore, after the extensive examination of which graft type is more effective for individuals with ACL reconstruction, literature supports that a patellar-tendon graft was more appropriate. Although quadriceps were found to function at a rate less than before the ACL reconstruction, it was a slight decrease in activation between the injured and uninjured legs, thus displaying its benefits as well.
Summary and Conclusion
To reiterate, the following themes were analyzed for individuals who have undergone ACL reconstruction and rehabilitation; changes in gait patterns, quadriceps muscle group activation, and the variation in results based on the graft type used during ACL surgery. It was confirmed that the graft type was crucial in determining how an individual could perform post-surgery and also gave validation to how their gait, or walking patterns could also benefit and provided a method to improve the quadriceps muscle groups.
Using the aforementioned research above can help develop guidelines that may be utilized by individuals who have experienced an ACL tear. First, the injured individual should be recommended to choose the patellar-tendon graft when having their ACL reconstructed, as it will allow their quadriceps muscle group to have a small variance in muscle activation when being measured after the injury. Secondly, the quadriceps muscle group is affected when the leg is lifted while an individual is performing physical movements. For example, if an individual is able to lift their leg with minimal pain and/or increased mobility, then walking patterns, or gait, will be positively affected as well. As such, if a specific reconstruction graft is used on the ACL in combination with open kinetic chain exercises the quadriceps, they will together result in a significant improvement of an individual’s ACL, with functioning capacity slightly less than it was prior to injury.
In conclusion, there have been many studies published explaining the behavior and function of muscles after the ACL has gone through rehabilitation and reconstructive surgery. These studies help to determine whether these muscles can be improved, or if the functional capacity it deteriorated post-ACL surgery. Upon analyzing the literature, there were three main themes that were repeatedly presented; functioning of the quadriceps muscle group, muscle function and gait, and benefits of specific ACL reconstruction grafts. Studying the relationship between these themes demonstrates how heavily affected an individual may be by how well their ACL can be restored. Simple everyday physical activities such as, walking up a set of stairs may be significantly easier to perform when the ACL has undergone effective surgery. Thus, as shown in this paper, muscles, or group of muscles may not be able to function at the same level after the ACL has undergone reconstruction and rehabilitation.
References
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Fisher, N. M., White, S. C., Yack, H. J., Smolinski, R. J., & Pendergast, D. R. (1997). Muscle function and gait in patients with knee osteoarthritis before and after muscle rehabilitation. Disability & Rehabilitation, 19(2), 47-55.
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