Sports injuries - prevention, anamnesis and rehabilitation A review using the example of ACL rupture

1 Introduction

While sporting activity is associated with numerous positive physical, psychological and social effects, sport and primarily playing sport also carries the risk of injury. Regardless of age and performance level, athletes can suffer injuries to soft tissues, bones, tendons, ligaments and nerves. These injuries occur either as a result of direct trauma or as a result of successive small overloads that only later result in an injury. The susceptibility of different individuals and the likelihood of injury in a particular sport is determined by age, gender and type of activity as well as performance level (Mafulli et al., 2011). The following work refers primarily to the area of ​​sports injuries and neglects the area of ​​similar or identical injuries that are not defined as sports injuries. To this end, it is important at the beginning of this work to explain which injuries can actually be recognized and interpreted as sports injuries. Since there is no uniform definition to date, certain precise epidemiological data cannot yet be classified in a longitudinal study. In the literature, a sports injury is usually assumed to be a complaint that occurs during a sports training or competition. In addition, it is recorded as such if it results in a training or competition being missed and/or medical treatment being necessary (Fuller et al., 2007). Due to the conflict that it is not possible to define exactly in which phase the injury can be recorded as over or that certain pain patterns as a result of a previous injury lead to a reduction in performance but not to an absence from sport, different injury rates are found for various injuries. The Verwaltungsberufsgenossenschaft (VBG) offers guidance, which has tried to analyze the injury situation in professional sport every year since 2016. The most common injuries in basketball and handball affected the ankle, in football the muscles of the back of the thigh and in ice hockey the head. An increased injury rate in the knee was also recognized in all sports, with the difference that the consequence of these injuries was a comparatively particularly high period of downtime. In Germany, there are around 1.9 million knee injuries every year. That's almost 14% of all injuries for which a doctor is consulted. This means that the knee has a special significance in medicine and, as the VBG health report shows, also in competitive sports. In the further course of the work, the anatomy and physiology of this body part will first be briefly summarized and then injuries and rehabilitation processes of a rupture of the anterior cruciate ligament will be explained in more detail. Finally, it should be mentioned that this work is not detailed enough to provide a full overview of the topic. This work is only intended to give a brief overview of the knee and its most common injury pattern as well as rehabilitation and prevention and to encourage readers to consult additional literature.

2 Anatomy and Physiology of the Knee

The knee joint can be described in the literature as a rotation-gliding joint (+rotation in flexion). Between the femur and tibia/fibula and behind the patella there is a joint with two joint parts that share a joint capsule. The places where the bones meet (articulating surfaces) are covered with articular cartilage, which is intended to ensure sliding ability. Stability and a lower susceptibility to injury are also ensured by the inner and outer meniscus. These can be described as two crescent-shaped (C-shaped) cartilage discs in the middle of the joint space. In addition to the "shock absorber" function, by increasing the contact surface between the tibia and femur, the inner meniscus in particular, which is fused to the rear part of the inner ligament, is intended to ensure less mobility during flexion and extension and thus reduce the risk of injury. In order to stabilize the knee in the lateral plane of movement, an inner and an outer ligament (syn. collateral ligaments) run from the femur to the femur/tibial head. The inner ligament is firmly fused to the joint capsule and the inner meniscus. Since the collateral ligaments are fully tense when the knee is extended and looser when bent, internal and external rotation is only possible to a limited extent in the flexed position. In order to ensure the stability of the knee joint as best as possible in all other planes, parts of both cruciate ligaments are tense in almost all positions. The anterior cruciate ligament is intended to prevent the femoral condyles from slipping backwards, especially during flexion. In the further course of the work, the anterior cruciate ligament, which runs from top-back to bottom-front, will be referred to as the ACL. The posterior cruciate ligament runs from top-front to bottom-back, is much less frequently affected by injuries and is described as the PCL.

The knee joint is exposed to high levels of stress in everyday life, even outside of sport. In addition to the constant static load that comes with carrying body weight, it must also bear five to seven times its body weight in everyday life, for example when climbing stairs or playing sport. The anatomy of the leg axis also means that the knee is generally subjected to high lever arm effects. The knee is exposed to extremely high loads, particularly in sports that involve jumping and rapid changes of direction. When a tennis player changes direction, the knee joint can bear more than ten times its own body weight. This fact means that it is subject to particular stress and, as a result, frequent injuries.

2.1 Knee injury and medical history

In the following part, this work will focus primarily on sports injuries. The most common sports-related knee injuries are: cruciate ligament injuries (usually ACL), meniscus injuries, cartilage damage and kneecap dislocation, patellar tendonitis. In the case of macrotrauma, it is common for several structures to be injured at the same time. Knee injuries mainly occur in biomechanical patterns in which high forces act in a short space of time. Examples of this are various changes in direction, strong impact, bending or rotation movements, and stopping movements. In sports, a distinction is made between injuries that occur with and without contact with an opponent. If, for example, a handball player lands on the foot of an opponent and this causes the injury, this is referred to as an injury with contact with an opponent. ACL injuries are much more common in women than in men. The connection between the female cycle and ACL injuries also requires further research.

If a macrotrauma occurs as a result of one of the two movement patterns or if there is pain that cannot be attributed to an event, a sports doctor should be consulted. The first step in the anamnesis is a description of the symptoms and then a detailed description of the mechanism of the accident. The injury history should also be asked at this point. The second step is inspection and palpation. This means that the wound/injury is examined visually and tactilely (malposition, leg axis, redness, swelling, gait, etc.). In the third step, the sports doctor tests passive mobility. Depending on the type of injury, there are various tests to examine the menisci, patella and other structures. The so-called drawer test is usually suitable for examining the cruciate ligaments for abnormalities. The Lachman test is also listed in the literature. Further examinations should then be carried out. Depending on the suspicion, X-rays, MRI or CT scans are suitable for the knee in order to produce clear results. A diagnosis is then made, ideally with the help of several sports physicians/radiologists. With this diagnosis, patients should then receive a direct referral to sports physiotherapists who will then deal with the rehabilitation of the injury.

3 Prevention at a glance

Before the rehabilitation is described in more detail in the paper, the topic of prevention must first be addressed. This order is deliberately chosen to illustrate the relevance of preventive measures so that the risk of a knee injury is reduced as best as possible. The term injury prevention refers to the reduction of injury rates at the population level. At the individual level, the risk profile can be changed for the better, but no future injury can be prevented whose occurrence is not predictable and certain (Begiebing 2023). Since various preventive contents, such as exact exercises, training content, lifestyle changes or even protective clothing, can be very specific and individual and the description of these would go far beyond the scope of this paper, two models are presented below that provide an overview of the classification of injury prevention. To use the example of knee injuries, various leg axis tests can be used. But the FMS (Functional Movement Screening) is also sometimes associated with knee injuries. To give another example, strong leg strength (front and back thighs) as well as minimal lateral deviation and trained landing skills (proprioceptive training) are the most important preventive measures for knee injuries. To understand the extent to which prevention can take place, the model by van Mechelen, Hlobil & Kemper (1992) can be used. The authors describe 4 steps through which injury prevention can occur:

1. Assessment of the extent of the sports injury problem based on epidemiological data including incidence and severity of injuries

2. determination of injury causes and mechanisms

3. Introduction of preventive measures based on the two-step

   information received

4. Evaluation of the effectiveness of the measures by repeating the first

   step.

In addition to this model, preventive measures can be easily integrated into the accident prevention matrix developed by Haddon (1980). This includes pre-crash measures (1). This includes, for example, changing individual risk factors, such as psychological stress or insufficient strength. But environmental measures, such as introducing certain rules for duels in training or appropriate protective clothing, also fall under this first point. Crash measures (2) are about preventive measures that athletes can use during potentially dangerous situations. Examples of this are ensuring sufficient training (see monitoring using the BORG scale) or certain fall techniques, as well as external safety equipment (nets, mats, equipment). The third point, post-crash measures (3), is about reducing the damage after an injury and the risk of re-injury to the best of one's knowledge. While preventive measures can be taken, for example by having first aid equipment available, this mainly refers to well-structured sports rehabilitation.

4 Sports rehabilitation

Ideally, rehabilitation should be carried out by a team of different experts. A rehabilitation team in competitive sports is made up of a doctor, physiotherapist, athletic trainer, nutritionist and sports psychologist. Unfortunately, in most cases it is not possible for each expert to take full care of the rehabilitation process of a single recreational athlete. Nevertheless, the following explanation should clarify different focal points in the rehabilitation process for each individual person, so that in the best case scenario the person treating the patient can combine several tasks in one person. However, this team setting can also mean difficulties for performance centers, because it requires a very high level of correct communication. For example, permanent protocols with assessments and recommendations must be passed on so that all indicators and contraindications are taken into account.

The process of reintegration after an injury first involves healing the injured tissue and preparing this tissue for the resumption of function. This is followed by the so-called return to training, i.e. reintegration into sport-specific training and then the return to competition. The timing of the individual stages of tissue healing and the entire rehabilitation process (as well as the effectiveness of the stimuli) is influenced by a variety of systematic and local factors. These include age, lifestyle, degree of injury, gender, etc.

This complex process, which involves several phases, can be used as an explanation for the advantage of having several experts. For example, the doctor takes the anamnesis and carries out regular checks, while the active and majority of the collaboration is carried out by the physiotherapists. When the athletes have progressed to the point where the first specific movement patterns of the sport are possible, the athletic trainer should accompany the rehab and integration into team training. It is also the job of the athletic trainer to continue to train non-injured structures during rehabilitation. For example, in the case of a cruciate ligament injury, a great focus should be placed on training the upper body and core. Since injuries often only affect one structure, there is no reason not to put strain on the rest. This includes strength and endurance training.

The reduction in movement after an injury usually leads to atrophy. In order to avoid this and to optimize the rehabilitation process, it is important to keep this atrophy as low as possible. Strength training of the ipsilateral (non-injured) extremity also increases maximum strength and reduces the extent of atrophy on the contralateral side through the so-called crossover effect (Hendy et al. 2012 / Lepley & Palmieri Smith 2014). This transfer effect has been shown to be most useful with hypertrophy training and high volume as well as a long eccentric phase (Cirer-Sastre et al. 2017). Occlusion training can also be used during training of the loading structure to avoid further atrophy effects. Bands or cuffs can be used to generate pressure of around 230 mmHg (Martin-Hernandez 2013). Endurance training is also primarily the responsibility of athletic trainers. Programs should be chosen that keep basic endurance at as consistent a level as possible, as well as those that reconstruct the stress intervals of the sport as best as possible.

Many of these topics require further explanation at this point, which is why they have only been mentioned briefly. In summary, with regard to physiological and conditioning abilities, it can be said that after an injury, neuromuscular control, mobility and strength are particularly impaired. An imbalance also usually occurs, which increases the risk of re-injury and should therefore be avoided as best as possible.

In addition to these basic principles in the area of ​​the active musculoskeletal system, the literature shows significant effects of successful rehabilitation in relation to psychological interventions and the lifestyle of the athletes. Ferreira et al. (2013) and Fuentes et al. (2014) found that the interaction between therapist and athlete is the most important thing in rehabilitation, regardless of content. Furthermore, subjective expectations are important for the outcome. If an athlete is convinced of the interventions and the qualifications of the therapists, rehabilitation is on average more successful (Cormier et al. 2016). In addition to the trust that athletes should have in their therapists, confidence in their own abilities is important. If athletes state that they do not yet have complete confidence in their own bodies, the risk of re-injury is significantly higher. Therefore, it is important to ask questions and openly exchange information about the subjective state throughout the rehabilitation (Ivarsson 2017).

Finally, the team should look at the athletes holistically and educate them about nutrition, sleep and regeneration in terms of rehabilitation (Hall et al. 2010). Poor nutrition increases the inflammatory process and is not beneficial (Acton 2013) and poor sleep quality increases the risk of re-injury (Milewski et al. 2014). And the athletes' everyday and private lives must also be considered for optimal rehabilitation success. A high chronic stress level increases the perception of pain and can slow the regeneration of tissue structures by up to 60% (Jennings et al. 2014).

4.1 Rehabilitation for cruciate ligament injuries

At this point, a discussion would be appropriate as to whether an ACL rupture can be treated conservatively or surgically. Overall, the study results do not show any superiority of surgical treatment over conservative treatment (Saueressig et

al. 2022). Nevertheless, surgical treatment is recommended for most active young athletes (Diermeier et al., 2020). The currently high rates of osteoarthritis, meniscus damage and failed return to competition attempts regardless of the treatment method show a clear deficit in science and practice. With regard to specific rehabilitation of specific injuries in different individuals, it can be said that it is increasingly a matter of avoiding mistakes in order to achieve potentially greater success. Nevertheless, there are various protocols in the literature (cf. Melbourne ACL Rehabilitation Guide 2.0) that have so far proven to be frequently successful. In the appendix, a guideline compiled from various recommendations has been developed that the THW Kiel juniors use as a guide. In summary, the psychological and lifestyle aspects mentioned in rehabilitation must be taken into account. In addition, goals should be to restore knee function, such as ROM and strength. Imbalances should be avoided and sufficient dynamic knee stability should be maintained, which can also exist in the case of poor mechanical stability (laxity) (Thoma et al., 2019). Many performance centers already carry out a pre-injury screening in order to have various goals set in the event of an injury that can be used as a guide later.