tendons and ligaments | Biomechanics in the Wild

Dancers: Athletes or Artists?

Throughout history, there has been a long-standing debate about whether dancers should be classified as athletes or artists. Athletes need strength to be proficient in a sport. Artists require creativity to produce works of art. Dancers combine strength with artistry to not only leap high into the air but also look graceful as they do so. Yet, many people still refuse to classify dancers as athletes or even as athletic artists.

Knee Pain from Golf? Look No Further.

If you like golf, you probably remember watching Tiger Woods win the 2008 U.S. Open with a torn anterior cruciate ligament (ACL). This may have seemed like a rare injury for a golfer, as most golf-related injuries involve the lower back, but knee injuries due to the golf swing are more common than you may think. In fact, the prevalence of knee injuries in golf is roughly 18%, with an even higher percentage when you only consider the elderly. Since most of these injuries are a result of overuse, it is important for golfers to understand why these injuries occur if they want to keep playing for years to come.

Unlike traumatic injuries in high-intensity sports like football or basketball, most golf-related injuries are the result of overuse. As for the knee joint, there are multiple mechanical factors in the golf swing that contribute to overuse injuries. During the downswing, the lead knee rotates rapidly from a state of adduction (external rotation) to a state of abduction (internal rotation). This creates an abduction moment on the lead knee, which can cause ACL tears. The graph shows a plot of adduction/abduction moments on the knees during a golf swing, which was measured using force plates and retroreflective markers on golfers’ legs.

skeletal diagram of how the hip and knee joints move — Photo via Musculoskeletal Key

Graph of Adduction/Abduction Moment (Nm/kg) as a function of time for both knees during the golf swing. — Graph by Kim, et al.

The magnitude (roughly 1 Nm/kg) is not large enough to cause traumatic stress on the ACL but is enough to potentially cause an injury over many repetitions of the golf swing. In addition to rapid rotation, the lead leg undergoes rapid extension during the downswing. The combination of these movements in large volumes over time can lead to other ligament tears or osteoarthritis. Osteoarthritis occurs when tissues in the joint break down over time.

In addition to these biomechanical movements, other factors like pre-existing knee conditions play a significant role in golf-related injuries. Over 30% of golfers with previous knee pain feel that golf has made their symptoms worse. The same is true for golfers with a previous total-knee arthroscopy (TKA), as nearly 34.9% experience pain after playing. Considering that golf is very popular among the older population, it is important to understand how to limit the risk of injury in the golf swing.

While the golf swing can lead to overuse injuries, there are a few preventative methods golfers can implement to protect their knees. Several studies recommend that golfers rotate their lead foot open (towards the target) by roughly 30 degrees. This decreases the stress on the medial (inner) side of the knee, a common area for osteoarthritis. Another adjustment golfers can make in their setup is how close/far they stand from the golf ball during the swing. Standing closer to the ball lowers the peak abduction moment on the lead knee, while standing farther away reduces the peak adduction moment. Depending on which area of your knee is in pain or has experienced previous injury, you may want to implement these adjustments to your setup. If you are experiencing pain on the inside of your knee, you should stand closer to the ball. Conversely, if your pain is on the outside of your knee, you should stand further away from the ball. Other preventative methods include warm-up stretching and regular exercise to activate and loosen the knee joint and surrounding muscles. If you’d like to learn more about these preventative methods, click here.

The Science Behind Load Management: How Isometrically Overloading Tired Knees Can Promote Growth and Healing

Many athletes who experience pain right below the kneecap after a spike in volume of explosive physical activities (ie. running/jumping) are diagnosed with patellar tendonitis, commonly referred to as runner’s or jumper’s knee. The suffix “itis” is Greek for inflammation and a common remedy is rest to reduce the inflammation. In some cases, an initial rest period combined with physical therapy to strengthen surrounding muscles such as the hip flexors and gluteus medius is enough to alleviate the knee pain for good, in other cases the rest is of no benefit or even worsens the patellar tendon’s condition and starts a chronic cycle of resting and then returning to activity in more pain than before. In these cases a more accurate diagnosis of patellar tendinopathy is correct. Patellar tendinopathy implies chronically recurring pain on the anterior of the knee that is difficult to treat. In such cases, an MRI often reveals small lesions throughout the patellar tendon indicating that the tendon is structurally damaged and not just inflamed. A better understanding of the patellar tendon’s biological composition, and biomechanical function may help to resolve future cases of patellar tendinopathy.

The Amazing Spider Silk

When one imagines the wonders of the natural world, the spider is not the first organism that comes to mind. However, possibly the most hated beings in all creation produce one of nature’s marvels: spider silk.

Properties

Spider silk has a number of properties that make it such an impressive material. First, spider silk is incredibly strong and tough. Spider silk is stronger than steel, and its toughness, or ability to absorb energy, is nearly three times that of Kevlar. And spider silk weighs less than both materials. These three properties alone would qualify spider silk as a super-material. The structural and ballistic industries stand to be disrupted by spider silk materials. For example, because spider silk can absorb energy better than Kevlar and is more lightweight, spider silk would be an excellent material for military and civilian self defense applications.

Spider silk also has an elasticity similar to that of human tendons while exhibiting a near perfect resistance to fatigue. Hennecke et al. show that spider silk has a similar stress-strain curve to that of a human tendon, and both materials have a memory which allows them to recover their form after loading. Tendons are constantly being loaded and unloaded throughout their life. Finding adequate materials for artificial tendons is particularly difficult, because most materials begin to lose their properties in cyclic loading, leading to a defined and small life time for the number of cycles tendons are forced through. But spider silk does not appear to lose its strength or elasticity even after high numbers of cycles.

In addition to these physical properties, spider silk also has been found to be both antiseptic as well as biocompatible. Spider silk has been used for medicine since ancient times due to its antiseptic properties, and for this reason, as well as its strength and toughness, spider silk is an excellent component in salves and bandages. Artificial tendons are prone to infection, and so spider silk’s antiseptic property is another reason why it is an ideal material for this application. Because spider silk is also biocompatible, as well as tough, it is a viable material for organ repair.

Let Kids Be Kids: The Unnecessary Dangers of Youth Sports Specialization

The allure of athletic success is hard to ignore in today’s society. The opportunities, notoriety, and wealth that come along with prowess in a particular sport are certainly enticing and have contributed to a growing trend towards youth sports specialization, where athletes focus on one sport from a very young age. And while the work ethic of these young athletes is admirable, their reasoning and that of their parents is a bit flawed.

Tendon Talks

Listen in today as we sit down with Nixon Dorvilien and Bendu Yeaney to discuss achilles injuries, specifically in the sport of basketball.

Oops I Did It Again: The Biomechanics Behind Repetitive Ankle Injuries

Ankle injuries – either sprains or fractures – are one of the most common sports traumas plaguing the US today. Sprains are overextensions or tears in ligaments. Fractures, on the other hand, are broken bones.

Ankle Sprains: An Epidemic in the World of Athletics

Have you ever been out running on a gorgeous fall day, only to have the run cut short by a painful misstep on a tree root covered by leaves? I have, and let me tell you – it’s awful! And even if you aren’t a runner, according to the Sports Medicine Research Manual, ankle sprains are a common, if not the most common, injury for sports involving lower body movements. Now, the solution to preventing this painful and annoying injury could be as simple as avoiding tree roots and uneven ground, but the real problem behind ankle sprains deals with the anatomy of the ankle.

Tearing and repairing the meniscus

How does someone go from being the youngest NBA MVP one year to barely making headlines the next? Ask Derrick Rose. After being named the youngest MVP in the NBA, Derrick Rose tears his ACL the next year and then tears his right meniscus twice in the span of three years. Knee injuries have not been kind to Derick Rose, but how does one tear their meniscus and how does it get repaired?

What is Tommy John surgery?

In July of 1974, Tommy John, pitcher for the Los Angeles Dodgers, felt a twinge in his throwing arm, and could no longer pitch. Dr. Frank Jobe tried a new kind of surgery on John’s elbow, and after missing only one season, Tommy John returned to the mound in 1976 and continued pitching until 1989.

How?

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