Tag Archives: sports injury

Patellar Tendinitis: The Kryptonite of Jumping Athletes

Volleyball is a sport of quick movements. For hitters, one of the most common movements in the game is the jump, whether that be to block or to hit. Although a higher vertical leads to improvement in game performance, it can increase the risk of developing a serious injury that affects many volleyball players: patellar tendinitis. This condition is associated with pain and tenderness directly below the knee cap that is especially apparent during explosive, jumping movements. But what exactly causes this condition? And what can be done to remedy it?

A schematic of the knee and patellar tendon.
Image from Wikipedia “Patellar Tendinitis”

Since volleyball is such a quick game, muscle memory is required to react to different situations that can occur. The main way to build muscle memory is repetition. Therefore, young volleyball players are encouraged to play the sport as much as possible. For many athletes, this means playing for their school during that season and then playing for an independent club for the rest of the year. Although this increases the athlete’s skill level, it also increases the chance of patellar tendinitis, according to a study.

Besides overuse, lack of ankle mobility can also lead to a higher risk of the condition. A study found that players that couldn’t flex their ankle upward past 45 degrees could have 2 times the risk of patellar tendinitis as players with a higher ankle mobility. This is most likely due to the ankle and calf’s role in absorbing impact upon landing. Less absorption by the ankle causes more force to be put on the patellar tendon. This is bad news for volleyball players who often have poor ankle mobility due to a past injury.

There are a few ways to treat patellar tendinitis. For an orthotic approach, players use straps or tape around their patellar tendon. Some think this is simply due to the fact that the strap or tape makes the athlete feel more stable, which allows them to load the tendon more properly. However, a study done in 2011 analyzed the strain in the patellar tendon using a computational model. The researchers found that the patellar tendon strap increased the angle between the tendon and the kneecap, which caused the strain to decrease. Decreased strain means that the tendon stretches less, which would decrease the incidence of patellar tendinitis. Another way to treat the condition is surgically. One of the more simple surgeries is a removal of the dead or torn tissue of the patellar tendon. This allows new, healthy tissue to form.

A strap being put around the patellar tendon that can ease pain.
Image from Sports Injury Clinic “Patella Tendon Taping”

Patellar tendinitis is a serious condition affecting many high-level athletes. Although there isn’t a simple cure, researchers have brought to light different causes and treatments of the condition. These can be used to help athletes remedy the pain they are experiencing and perform at their best.

Sources:

Study on How Vertical Affects Patellar Tendinitis

Study on How Training Volume Affects Patellar Tendinitis

Ankle Flexion Study

Patellar Tendon Strap Proprioception Study

Patellar Tendon Strain After Applying a Strap

Additional Reading:

Clinical Trial on Patellar Tendon Strap

Runner’s Knee: Knee Pain Isn’t Just for Old People

Don’t knee problems only plague old people or people who have run for a lifetime? I questioned this when, for the seventh time in a row, my knee was hurting only a mile and a half into my run. I’m too young for this! However, a plethora of information suggests that knee pain is perhaps not so uncommon in younger runners and athletes as I thought.

The American Family Physican published an article detailing one form of knee injury informally called “Runner’s Knee”. A shockingly high number, between 16 and 25 percent, of running related injuries fall into this categorization. Medically termed patellofemoral pain syndrome (PFPS), the ailment manifests in pain or stiffness in the knee, particularly when bent in load-bearing scenarios such as walking, running, jumping, or squatting. The patellar region experiences shocking loads even in the day to day: in walking alone the region experiences up to a half the person’s body weight while in an activity like squatting it can experience up to seven times one’s body weight. Often the pain is hard to pinpoint but occurs in or around the front of the knee within a circular range. It can inhibit or put a stop to training, however, if addressed early on, can often be healed or corrected much more quickly.

an animated image of a runner mid-stride with the pain region for patellofemoral pain syndrome highlighted
Photo by www.scientificanimations.com from Wikimedia Commons

In PFPS, the patella (the kneecap) moves abnormally within the groove on the end of the femur (called the femoral trochlear groove) due to imbalanced or unusual loads on the joint. This results in over-stressing the joint and causing pain. Several possible causes exist for PFPS; here, I will focus on three of most commonly cited: increased intensity of activity, weak hip muscles, and overpronation.

an image of the muscular and skeletal structure of the knee, including the patella
Photo by BruceBlaus on Wikimedia Commons

Increased Activity

One review explored that women are more likely to suffer from PFPS. In this study they saw that women of higher activity levels were not necessarily more likely to experience pain due to PFPS than women who had a lower activity level. Rather, a substantial increase in activity level seemed to be the cause of pain. Therefore, more than overuse of muscles or joints, PFPS often develops with increased amounts of activity, or temporary overuse, such that the body is not prepared to handle the increased and repetitive forces on the knee.

Weakness in Hip Muscle Strength 

This study shows that lower extremity mechanics and motion can be affected by hip strength. For example, inward rotation of the hip can be lessened through strengthening of hip muscles that counteract that rotation. With less internal hip rotation, the knee abduction moment (the tendency of the knee, due to reaction forces from the ground, to rotate  inward and away from the balanced midline of the knee joint) decreased which often resulted in less stress in the knee. Therefore, the review suggests that strengthening hip muscles can lower the patellofemoral joint stress and help treat PFPS. 

Overpronation

Pronation refers to the natural movement of one’s foot and ankle slightly inward while stepping. When the ankle rotates too far inwards, it is called overpronation. Overpronation can lead to further improper structural alignment in the lower body as the tibia rotates improperly in response to the ankle rotation. The tibia’s rotation then disrupts the natural movement of the patellar joint and can contribute to PFPS. In many cases, overpronation can be corrected through use of orthotic shoe inserts that prevent the over-rotation of the foot and ankle.

In conclusion, while we may often associate knee problems with older people or arthritis, PFPS affects many athletes, particularly runners, at any age. Often, proper training programs that do not accelerate activity too quickly, strengthening exercises that focus on the hip muscles, and proper, overpronation-correcting footwear can treat or prevent an individual from being affected by PFPS. Check out some strengthening exercises here.

Exciting Advance in ACL Repair

Anterior Cruciate Ligament (ACL) injuries are among the most common in sports, with nearly 100,000 tears annually. Additionally, the rate of pediatric tears has been increasing at a rate of 2.3% each year for the past 20 years. The high incidence of this injury is in part due to the structure of the knee complex, where the ACL is located. The ACL helps connect the two longest bones in the body and is responsible for rotation and transferring body weight to the ankle. Specifically, the primary functions of the ACL are to prevent the tibia from sliding too far in front of the femur and to provide rotational stability to the joint. This rotational motion, combined with a lack of muscle support at the knee, is why so many athletes tear their ACL. A recent paper looked into how a team of doctors led by Dr. Martha Murray at Boston Children’s Hospital have come up with a promising new approach to repairing the injured ligament.

Two side views of the knee joint, one showing a healthy knee and one showing a complete ACL tear.
Photo by BruceBlaus on wikimedia.org

Due to its environment, ACLs do not repair on their own like other ligaments do. The synovial fluid, which resides in the knee complex to reduce friction in the joint, limits blood flow to the ACL and PCL (posterior cruciate ligament). When injuries occur to these ligaments, the lack of blood flow prevents clotting. In most other ligaments, clotting would occur and would function as a “bridge” for the two ends of the torn ligament to grow and heal across. Due to ACLs not being able to undergo this process, the current method for repair is to take a graft from the patient’s hamstring or patella and replace the torn ACL with the new graft. While this method is typically successful, Dr. Murray’s team estimates that the re-tear rate is about 20% and up to 80% of patients develop arthritis in their knee 15-20 years after the surgery. To combat this, Dr. Murray drew inspiration from how other ligaments heal and developed Bridge Enhanced ACL Repair (BEAR). The premise of this technology is to take a “sponge” that is composed of proteins that are naturally found in the ACL, and insert it between the torn ends of the ACL.  Using sutures, the sponge is moved into position and the two ends of the ACL are pulled into the sponge. Blood is then drawn from the patient and inserted into the sponge. This environment acts as a blood clot and stimulates the ACL to repair itself. Clinical trials have shown that the sponge resorbs completely after 8 weeks, at which point the two ends of the torn ACL have begun to join back together. While the BEAR treatment is still relatively new, early results are encouraging with patients seeing similar results to patients that undergo traditional ACL reconstruction. Though it is difficult to predict the rate at which patients who receive BEAR treatment will develop arthritis, animal testing has shown lower instances of osteoarthritis development, which is promising news for those who suffer from this common injury.

For more information about the BEAR technology check out Boston Children’s Hospital website or this recent article. A short video detailing the technology can also be seen below.

Artificial Turf: Game Changer or Game Ender?

Woman plays soccer on artificial turf field
Soccer player on artificial turf field
From Pixabay

Artificial turf fields were first introduced in the late 1960s and have grown tremendously in popularity since. Today, artificial turf fields can be found at all levels of sport, from youth league to professional, and across many different sporting disciplines. A major reason they are so popular is because they offer a consistent, low-maintenance, year-round green playing field in all weather conditions and climates. However, despite the benefits they provide, artificial turf fields are not without controversy. Even though artificial turf mimics grass in appearance, its properties are much different.

Of these properties, two are especially relevant to injuries sustained while playing sports, especially concussions and injuries to the knee and ankle. The first of these two is the field’s ability to absorb shock. Older artificial turf fields are often much harder than natural grass fields, which leads to greater impacts on athletes, which can then result in higher rates of concussions and other injuries. As artificial turf technology has developed, however, installation procedures and field composition have improved and greatly reduced the risk of injury.

The second of the two properties is the friction of the field, or how well an athlete’s cleats grip the turf. Because of their greater consistency and density, artificial turf fields can generate more friction than natural grass fields, allowing greater force to be generated at the contact point between an athlete’s foot and the ground. This is both a positive and a negative. Positively, the greater friction generated by athletic moves on artificial turf surfaces enable an athlete to perform at a higher level by enabling quicker changes in direction and more explosive movements. However, these greater forces can overload weaker parts of the anatomy, especially the ligaments in the knee, and cause injury. Numerous studies have found that rates of serious knee injuries, such as ACL (anterior cruciate ligament) tears, are found to be increased on artificial turf fields.

A major reason for this is because the knee is a hinge joint, meaning that it only allows straightening and bending motion while resisting rotation. Within the knee, tendons attach muscles to the tibia/fibula and the femur so that the knee can be bent voluntarily, four major ligaments attach the femur to the tibia/fibula to stabilize and restrict the knee’s motion, and a variety of cartilage and fluid sac structures ensure smooth and consistent motion. While robust together, each individual component in the knee is susceptible to injury if it is subjected to a force in an unusual or extreme way, which could happen while changing direction rapidly, incorrectly landing a jump, or during a collision. On an artificial turf field, the risk of damaging ligaments, cartilage, or other structures in the knee is increased because greater forces can be generated from the ground and because the foot may stick in the turf while changing direction and cause inadvertent rotation in the knee.

Nevertheless, even these risks can be somewhat mitigated by taking steps to avoid injury like the one recommended by The Polyclinic.

 

 

Striking Out the Myths behind the Curveball

Anybody who has played baseball growing up was probably told “Don’t start throwing a curveball until you are ‘X’ years old.” That “X” in there for the age was normally around fifteen or sixteen years old depending on who you asked. When an eager, young ball player responded with “Why,” it was normally answered by “Because you will hurt your elbow and shoulder.” No sixth or seventh grade kid is really going to question that statement beyond asking another adult, and subsequently getting the same answer. Likewise, no youth baseball coach has really put in the effort to research whether or not learning to throw a curveball is detrimental health of young athletes.

A study was recently conducted by professionals at Elite Sports Medicine at Connecticut Children’s Medical Center to find out the answer. The study was aimed to analyze the shoulder and elbow joints of several teenage pitchers as they threw multiple fastballs and curveballs. They were specifically looking at the moments put on the elbow and shoulder and comparing those between pitches. A moment is a measure of a force on an object and the distance away from the object the force is being applied, mostly resulting in rotation. A moment can also be thought of as torque.

This image shows the grip and wrist position for a curveball
From McGraw, How to Play Baseball, a Manual for Boys

After warming up, the athletes selected for the study had reflective markers placed on their body. These markers assisted in gathering information for “3-Dimensional motion analysis”. This analysis allows the researchers to record “kinematic and kinetic data for the upper extremities, lower extremities, thorax, and pelvis” for both the fastball and the curveball. The researchers found that the moments in the shoulder and in the elbow are lower when throwing a curveball compared to a fastball. This means that the rotational force put on the joints is actually less severe in a curveball than a fastball. The only thing found that is more intense in a curveball than a fastball is the force on the wrist ulnar, which is used when making the motion trying to touch the wrist to the pinky finger. The wrist and forearm motion and forces were the only significant differences between the two pitches.

From this data it is easy to see that the reason for not learning curveballs at a young age has nothing to do with shoulder and elbow injury. There may be a reason related to wrist injury, but that is yet to be explored. A fastball is actually harder on the joints than a curveball. For whatever reason, youth coaches have always preached not to throw curveballs until you absolutely need to. They may have their reasons, but science has shown that it is not realistic to blame injuries.

For further reading on this topic, please see these articles from Driveline Baseball, The New York Times, and Sports Illustrated.

Do Running Injuries Depend on the Running Surface?

Photo by MabelAmber on Pixabay

Imagine that you are on your typical route for a morning run when you decide to change things up. Instead of following the path of the sidewalk like usual, you take a shortcut across the soft grass and run alongside the concrete for awhile. No big deal, right?

Although this change in running surface may not seem to be a big deal, there is a lot more going on behind the scenes than runners are consciously aware of. As you step from the firm concrete to the soft soil, your body automatically adjusts its stride to accommodate the change and you hardly notice the difference. Specifically, your legs calibrate their angle relative to the ground and tension in the quadriceps before taking a step onto a new surface to maintain balance and speed as you run.

Image of a person running with one leg modeled as a spring
Modified image by Kulmala et al. in Scientific Reports from nature.com

In a study performed by Daniel Ferris et al., researchers examined the mechanics of surface-dependent running. Participants ran at a constant speed across a track with both a rigid and a compliant surface, and the force of the leg, time of foot-to-ground contact, and angle of the leg at initial ground contact  were measured for each trial. The resulting data were then analyzed by modeling the legs of the runners as simple springs (left). The research concluded that runners quickly and instinctively adapt the stiffness of their legs in response to changes in surface elasticity. This allows runners to keep a constant running speed without wasting energy due to excessive vertical motion of the torso as the body adjusts to the new surface.

Leg modeled as springs moving from one running surface to another
Image by Ferris, et al. in Journal of Biomechanics

Without this intrinsic adaptation of leg stiffness, runners would have to drastically change their strides to remain upright as they ran from surface to surface (right, with stiffness denoted as kleg). In fact, leg stiffness decreases when you run on rigid surfaces and increases when you run on springy surfaces. In short, the stiffness of your legs compensates for the firmness of the ground you are running on.

So how does leg stiffness translate to injuries and injury prevention?

First of all, it is important to note that injuries to muscles and ligaments have different causes and symptoms than injuries to the bone. Knowing this, experts suggest preventative measures specific to the type of injury. For example, one article claims that high leg stiffness while running corresponds to a higher risk of bone injuries. As a result, we can use the information above to deduce that the best way to prevent stress fractures is to run on hard surfaces such as concrete or asphalt in shoes with little cushioning. Conversely, low leg stiffness corresponds to a higher risk of muscle and ligament injuries and the best way to prevent these injuries is to run on dirt, grass, or a track in padded shoes. The video below explains this correlation in further detail.

See also padded shoes paradox and leg stiffness and running performance for further reading.

 

What Happened to Markelle Fultz’s Shot?

What happened to Markelle Fultz? This is the question on the minds of many basketball fans who have watched a promising player slip into a sharp decline in his first two seasons in the NBA. The former 1st pick in the 2017 NBA draft was known in college for his ability to score; however, so far in his career, his shooting statistics have fallen dramatically as he seemingly forgot how to shoot the ball. A couple of painfully awkward shots can be seen below as Fultz tried new methods of shooting the basketball:

A few months ago, his difficulties were diagnosed as neurogenic thoracic outlet syndrome (TOS). But what is neurogenic TOS and how does it impact Fultz’s shot?

Male figure shown with location of thoracic outlet between the base of the neck, the clavicle and the arms.
White shaded area shows the position of the thoracic outlet on the body. From University of Washington School of Medicine in St. Louis.

A paper by neurosurgeons Jason Huang and Eric Zager of the University of Pennsylvania on TOS gives insight into Fultz’s diagnosed condition. The thoracic outlet is an intersection of nerves and blood vessels that run through the gaps between the base of the neck, the clavicle, and the arm. Neurogenic TOS occurs when there is compression of the brachial plexus, a bundle of nerves that run between the scalene muscles, the clavicle (or collarbone), and the subclavian arteries. When certain arm motions are performed, the space in the thoracic outlet can become smaller, leading to increased compression.

A picture shows the muscle, nerves, arteries, and bone that make up the thoracic outlet.
Representation of the thoracic outlet including the scalene muscles, the brachial plexus nerve bundle, the subclavian arteries, and the clavicle bone. From Huang and Zager, in Oxford Academic.

Particularly in men, it is common for the scalene muscles to cause TOS, and research has shown that it can happen through repetitive use or sports. There have been reports of baseball pitchers diagnosed with TOS because of the awkward arm motions from throwing the ball.  Often TOS is accompanied by a dull pain in the neck, shoulders and arm where affected, but is not sharp and is often characterized by discomfort, especially with overhead motions. This would explain why Fultz’s shooting motion could be uncomfortable and cause his brain to focus on the pain caused by the nerve compression.

 

So what is the treatment and what is Fultz’s timetable for return?

Sometimes for patients with TOS, surgery is an option, but not often for the type Fultz is likely experiencing, since they are tricky and carry high risk due to the presence of major nerves and arteries. Often a more conservative treatment is prescribed, and it seems as though Fultz is doing physical therapy. His initial timetable for return was listed at 3-6 weeks, but there is no indication of an immediate return, and there is little data to predict the length of recovery with physical therapy.

Because of the unpredictability of the treatment, the uncertainty surrounding Fultz seems to be just as thick with the diagnosis of TOS as it was before. However, the ability for Fultz to recover and relearn how to shoot will be imperative in determining whether he will return to his original form as an elite scorer or become one of the biggest busts in the history of the NBA.

 

Further reading on this topic can be found from The Washington University School of Medicine and In Street Clothes.