Biomechanics of Knee Injuries

July 3, 2024

Dive into the biomechanics of knee injuries, from common types to prevention strategies. Be knee-savvy!

Knee Injuries Overview

The knee, the largest joint in the body, is often susceptible to injuries, particularly in the realm of sports. Knee injuries account for about 10–25% of all sports-related injuries [1]. This equates to an estimated 2.5 million sports-related knee injuries annually, making it the most commonly injured joint by adolescent athletes [2].

Common Knee Injuries

A variety of knee injuries can occur, specifically in sports activities like running, football, basketball, lacrosse, or skiing. These activities present an increased risk due to the harsh movements involved. Factors such as sudden stops, twists, turns, pressure on the knee joint while running, overuse, or trauma from blunt force contribute to knee pain or injury.

Common knee injuries include:

Sprains and strains: These are injuries to the ligaments and tendons, respectively, that support the knee joint.
Meniscus tears: This injury occurs when the cartilage in the knee is torn, often due to a twisting motion.
Fractures: These injuries involve a break in one of the bones in or around the knee.
Overuse injuries: These injuries are caused by repetitive stress on the knee joint.

These injuries can lead to damage of bones or connective tissues in the knee, making them among the most common joint injuries [4].

Symptoms and Diagnosis

The symptoms of knee injuries can vary depending on the type of injury and its severity. Common symptoms include pain and swelling, difficulty bearing weight, and instability. These symptoms can make it challenging to walk or move the joint [2].

Diagnosing a knee injury typically involves a physical examination and imaging tests, such as X-rays or MRIs. The clinician will evaluate the knee's range of motion, strength, stability, and overall structure to determine the extent of the injury.

Understanding the biomechanics of knee injuries is crucial for prevention, treatment, and recovery. In the following sections, we will delve deeper into the biomechanics of common knee injuries, specific knee injuries in athletes, treatment and prevention strategies, and the impact of gender and playing surfaces on knee injuries.

Biomechanics of Knee Injuries

Understanding the biomechanics of knee injuries involves exploring the role of various anatomical structures in the knee and the factors that contribute to injuries. As per Medical News Today, the knee is the largest joint in the body and the most commonly injured joint by adolescent athletes, with an estimated 2.5 million sports-related injuries annually.

Role of Ligaments

Ligaments in the knee play a crucial role in maintaining stability. Acting like strong ropes, they connect bones and prevent excessive motion. There are four main ligaments in the knee, each having a unique function but collectively contributing to the overall stability and movement of the knee.

Injuries to these ligaments can seriously affect the biomechanics of the knee, leading to symptoms such as pain, swelling, difficulty with weight bearing, and instability. These injuries can occur as a result of a sudden twist or turn, especially while the foot is planted on the ground, or from a direct blow to the knee.

Impact on Meniscus

The meniscus in the knee serves as a cushion or "shock absorber," facilitating smooth movement of the bones without them rubbing against each other. The menisci also contain nerves that aid in balance, stability, and weight distribution between the femur and tibia.

Damage to the meniscus can significantly affect the biomechanics of the knee, often resulting in pain, swelling, and instability. Such injuries are commonly seen in sports that involve sudden twists and turns or direct impacts to the knee.

Factors Contributing to Injuries

Several factors contribute to knee injuries. For athletes, the type of sport and the specific movements involved can play a significant role. According to a study cited by NCBI, complete anterior cruciate ligament (ACL) rupture is commonly seen in football, basketball, and volleyball players, while meniscal injuries are often experienced by street runners.

Other factors include overuse, as seen in more than 70% of trail running-related musculoskeletal injuries. Running through persistent musculoskeletal pain can also lead to altered mechanics, producing compensatory biomechanics and loading at other anatomical sites.

Understanding the biomechanics of knee injuries is key to determining appropriate treatment and prevention strategies. It also helps athletes, coaches, and healthcare professionals develop effective training programs that minimize the risk of these injuries.

Specific Knee Injuries in Athletes

Athletes often experience specific types of knee injuries due to the unique demands and biomechanics of their respective sports. Understanding these injuries can aid in prevention strategies and treatment methods.

ACL Injuries in Various Sports

The anterior cruciate ligament (ACL) plays a crucial role in maintaining knee stability. Injuries to the ACL are common among athletes, particularly those involved in sports that require quick changes in direction and jumping, such as football, basketball, volleyball, handball, and jiu-jitsu NCBI.

Sport	ACL Injury Prevalence
Football	High
Basketball	High
Volleyball	High
Handball	High
Jiu-Jitsu	High
Ballet/Dance	Low
Judo	Low

Patellofemoral instability, another common knee ailment, has been noted as prevalent in ballet, dance, and judo athletes.

Meniscal Injuries in Runners

The meniscus, a crescent-shaped cartilage in the knee, often suffers injury in street runners. These injuries can occur due to the repetitive impact of running on hard surfaces, leading to wear and tear over time NCBI.

Trail running, in particular, presents a unique set of biomechanical challenges. More than 70% of injuries in trail running are due to overuse, primarily affecting the knee and ankle PubMed.

Running through persistent musculoskeletal pain can alter the runner's biomechanics, leading to additional stress at other anatomical sites. To mitigate the risk of injury, trail runners are advised to maintain their cadence within ±5% of the cadence adopted in level running during downhill sections. This can help attenuate joint loading and reduce energy cost PubMed.

Furthermore, adopting a more forefoot strike and an elevated step rate can reduce impact loading and patellofemoral joint force in various terrain stretches. These adjustments can potentially lower the risk of meniscal injuries in runners PubMed.

Understanding the biomechanics of knee injuries in specific sports can help athletes and medical professionals devise effective prevention and treatment strategies. It's important for athletes to listen to their bodies and seek medical advice when needed to maintain their knee health.

Treatment and Prevention Strategies

Successful rehabilitation and prevention of knee injuries hinge on a combination of rest and recovery, strengthening exercises, and structured prevention programs. This combination is vital in ensuring the knee regains its full function and is protected from future injury.

Rest and Recovery

The initial treatment of knee injuries often involves rest, ice, elevation, and over-the-counter pain relievers. This approach, commonly known as RICE, helps reduce inflammation and promote healing in the injured knee. After the initial period of rest and recovery, strengthening and stretching exercises are introduced to promote healing and restore function to the knee. In some cases, surgery may be necessary to repair significant damage to the knee structures [2].

Strengthening Exercises

Exercise-based knee injury prevention programs are integral to recovery and prevention of future injuries. These programs should include strength, plyometric, and core conditioning training, performed for at least 20 minutes multiple times a week. Additionally, sport-specific training should occur for more than 30 minutes multiple times per week.

Clinicians can utilize exercise-based neuromuscular training programs during the late phase of ACL reconstruction rehabilitation for the secondary prevention of ACL injuries. Such programs serve to restore balance, coordination, and strength to the knee, mitigating the risk of re-injury.

Prevention Programs

The implementation of ACL injury-prevention training programs can significantly reduce the risk of knee injuries in athletes. These programs improve an individual's neuromuscular control and lower extremity biomechanics, key factors in the biomechanics of knee injuries.

Recent evidence indicates that ACL injuries may be prevented through the use of multicomponent neuromuscular-training programs. These programs typically include strength training, plyometrics, and balance exercises designed to enhance knee stability and reduce the risk of injury.

Studies have shown that multicomponent preventive training programs reduce the rate of ACL injury in both male and female athletes. ACL injuries were reduced by 51% to 62% when athletes performed a preventive training program. Those who participated in a preventive training program had a greater relative risk reduction (RRR; 70%; 95% confidence interval [CI] = 54%, 80%) and lower odds (odds ratio = 0.54; 95% CI = 0.35, 0.82) of sustaining an ACL injury than those who did not.

In conclusion, a holistic approach encompassing rest and recovery, strengthening exercises, and preventive programs is crucial in the treatment and prevention of knee injuries. By understanding the biomechanics of knee injuries, individuals can make informed decisions about their treatment and prevention strategies, minimizing the risk of future injuries.

Gender Disparities in Knee Injuries

When delving into the biomechanics of knee injuries, it's essential to consider the gender disparities that exist. Research has shown distinct differences in the prevalence and risk factors for knee injuries between male and female athletes. This section explores these disparities, with a focus on risk factors for female athletes and the potential hormonal influence on injuries.

Risk Factors for Female Athletes

Female athletes have been identified at an increased risk of injuring their Anterior Cruciate Ligament (ACL), particularly during certain sports. Injury rates are reported to be 3.5 times greater for basketball and 2.67 times greater for soccer compared with male athletes participating in these sports at similar levels.

The heightened risk of knee injuries in female athletes can be attributed to several factors. For one, female athletes display different movement and muscle activation patterns compared to male athletes. Additionally, females have smaller ACLs with decreased stiffness values and different bony knee geometry, which can contribute to the increased risk of injury [7].

Furthermore, baseline values of potential risk factors for ACL injury differ between males and females. These differences could confound the effects of some risk factors or find associations with injury for some risk factors simply because they differ between the genders.

Another significant risk factor for female athletes is previous ACL reconstruction. This has been identified as a risk factor for subsequent non-contact ACL injury, both in the contralateral knee and for reinjury of the ACL graft.

Hormonal Influence on Injuries

The role of female sex hormones in knee injuries has also been examined. Estrogen and progesterone receptor sites on the ACL have introduced the hypothesis that these hormones may have an effect on the metabolism, composition, and biomechanical properties of the ACL [7].

However, it's important to note that while this hypothesis has been explored, there are currently no case-control or cohort studies in humans that have confirmed this. The potential influence of female sex hormones on knee injuries remains a subject of ongoing research.

In conclusion, understanding the gender disparities in knee injuries is crucial for injury prevention and treatment strategies. It's important for female athletes to be aware of these risk factors and consider them in their training and conditioning programs to reduce the likelihood of knee injuries.

Surface Impact on Knee Injuries

While understanding the biomechanics of knee injuries, it is essential to consider the role of the surfaces on which activities take place. Different surfaces can have varying impacts on the knee, potentially leading to injuries.

Role of Playing Surfaces

Playing surfaces can have a significant influence on knee injuries. Recent research suggests that the type of grass on a playing field can influence the likelihood of non-contact knee ligament injuries. For instance, fields with perennial ryegrass have been associated with fewer such injuries compared to those with bermudagrass. This may be because ryegrass is associated with lower shoe-surface traction than bermudagrass, reducing the strain placed on the knee.

Surfaces	Impact on Knee Injuries
Perennial ryegrass	Fewer non-contact knee ligament injuries
Bermudagrass	More non-contact knee ligament injuries

Surface-Related Risk Factors

Surface-related risk factors are a common denominator in knee injury clusters, highlighting the importance of regular safety checks of stadium surfaces. Examinations should be conducted for surface irregularities, excessive hardness, and potential excessive shoe-surface traction, all of which can contribute to knee injuries.

These findings emphasize the need for improved standards in the maintenance and selection of playing surfaces to minimize the risk of knee injuries. Further research is necessary to explore other surface-related factors and their impact on the biomechanics of knee injuries.

By understanding the role of playing surfaces in knee injuries, it's possible to implement strategies to minimize the risk. This includes choosing appropriate surfaces, maintaining them to a high standard, and adjusting footwear to match the surface conditions. These measures can help protect the knees and ensure the longevity of athletic performance.