Tag Archives: ankle

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.

Here, we will focus on sprains of which there are three grades. To help visualise a sprain, think of a Fruit By the Foot (the gummy fruit snack you may have eaten as a child). A Grade 1 sprain involves stretching like if you were to pull on either end of the fruit rope and small tears start to develop along the middle. A Grade 2 sprain develops when the tear is larger and originates from a side; a grade 3 sprain is a complete tear into two pieces.

A Little Background

The ankle joint, also known as the talocrural joint is a synovial hinge joint that mainly moves in dorsiflexion and plantarflexion 1. If you were sitting on the ground with both legs extended in front of you, dorsiflexion is the movement of your foot upwards toward your shin, and plantarflexion is the action associated with pointing your toes moving away from your body.

Video Explanation of Ankle Movements in Dorsiflexion and Plantarflexion

Sprains & Pains

The most common type of ligament injury are lateral ankle sprains or inversion sprains where the ankle joint over rotates in the outward direction, especially an inversion while in plantarflexion 2. Exercises that include running, jumping, and/or cutting put the athlete’s ankle at high risk for sprains. This is especially seen in soccer, football, basketball and volleyball players.

Depiction of ankle position with an inversion sprain. Light purple items are bones and have rectangular callouts, while red items are ligaments with circular call outs. Labeled items include: Tibia, Fibula, Talus, Cuboid, and Calcaneus bones as well as the ATFL, PTFL, and CFL (ligaments).
Figure 1 – Left Foot/Ankle in an over-rotation with main bones (in square callouts) and ligaments (in circle callouts) identified

Figure 1 above shows an ankle in the common and compromising position of an inversion sprain. The circled ATFL, PTFL, and CFL are ligaments in the joint, namely the Anterior Talo-Fibular ligament, the Posterior Talo-fibular ligament, and the Calcaneofibular ligament respectively. Additionally, the boxed call outs are bones in the foot.

Numbers show that close to 70% of patients that had experienced a lateral ankle sprain in the past repeated the same injury to their ankle1.

What is the medical explanation behind repeated ankle injuries?

One study by Doherty et al. followed emergency room visits for ankle injuries and found that 40% of patients with ankle sprains had to seek medical treatment for another ankle injury within the year. Yet, another statistic found that over half of people who experience ankle sprains don’t even go to a hospital.

Ankle sprains are sometimes deemed as a “walk-off injury“, or one that hurts momentarily but just needs a few minutes before resuming activity. However, many people suffer from prevalent and reoccurring ankle sprains. Officially dubbed Chronic Ankle Instability or Sprained Ankle Syndrome, this condition is characterised by a host of symptoms including pain, swelling, perceived and actual instability, balance issues, and joint weakness. Chronic Ankle Instability, or CAI more commonly, can also cause a decrease in physical activity, changes to walking or running form, onset arthritis, and problems with knees and hips due to overcompensation1.

The tried-and-true course of action to prevent CAI is efficient rehabilitation. A study showed that if the patient recovers fast enough, the body won’t change movement patterns.

Problem: Altered Movement Patterns

The changing of movement patterns in the ankle joint, or arthrokinematics1 is one of the main factors that contributes to CAI. The brain, like a protective mama bear, trains the body to operate (walk, run, jump) in a different manner to protect the strained ligaments. Over time, muscle memory kicks in and the compensation for ankle mobility becomes your new normal. This adoption of an incorrect form of walking, running, jumping, etc. can backfire and translate to repeated ankle injuries. This muscle memory has been identified as a neurosignature2 from Melzack’s neuromatrix of pain theory; however, this pain theory also describes how elimination of the pain, stress, or chronic symptoms associated with an ankle sprain can prevent reoccurrence – elimination, that is, through efficient rehab.

Solution: Efficient Rehabilitation

A quick recovery can be achieved through various muscle strengthening exercises from a licensed physical therapist or “ankle disk training,” which basically consists of a flat board mounted on a semi-circle. By standing on this unbalanced board, stability can be practiced as well as specific ligament targeting to build muscle. A more serious solution of ankle surgery showed a 90% success rate of mediating mechanical instability, but this is not a widely-practiced nor traditional treatment plan for CAI3. In fact, ankle taping and/or lace-up 3 bracing when exercising proved most helpful in preventing over rotations of the lateral ligaments.

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.

The ankle is made up of many ligaments, bones, and muscles. However, when sprained, it is the ligaments that are mainly affected. Connecting bone to bone, ligaments are used to support and stabilize joints to prevent overextensions and other injuries. The weaker a ligament is, the easier it is to injure. There are three main lateral (outer) ligaments supporting the ankle joint that can become problematic: the anterior talofibular ligament, the calcaneofibular ligament and the posterior talofibular ligament. According to a study from Physiopedia, these lateral ligaments are weaker than those on the interior (medial) of the ankle, with the anterior talofibular ligament being the weakest.

An image depicting the various ligaments of the ankle, both lateral and medial.
Anatomy of the ankle, highlighting the lateral and medial ligaments

The next question that has to be asked is why are these ligaments so much weaker than other ones? The answer to this question is based on their physical make up. Ligaments are made of soft tissue that has various collagen fibers running parallel to each other throughout it. The more fibers there are, the more structure and rigidity there is. Think of the fibers as a rope: The rope can stretch to a certain point, but once it hits that point it will snap and break. But if you have a thicker rope (such as the medial ligaments), it becomes much harder to break.

The ligaments on the outer part of the ankle have fewer collagen fibers than those on the inside of the ankle. Thus, when the ankle is moved in an awkward position, it is more likely that the lateral ligaments will break.

Once you sprain your ankle, the focus turns to treatment. Treatment will differ slightly for every individual depending on the severity of the ankle sprain. The simplest way to treat a sprained ankle is to follow the RICE (Rest, Ice, Compression, Elevation) method. Other forms of treatment include taping the ankle or using a brace to restrict movement and to add support and extra stability. Wearing proper footwear is another way that one can prevent and help treat a sprained ankle, as certain shoes are specifically designed to help avoid such injuries. To prevent future ankle sprains, exercises are recommended to help strengthen and stabilize the joint and surrounding ligaments and muscles.

For more information on ankle anatomy and sprains, check out these articles on BOFAS and SPORTS-Health.

High Heels: How They Can Affect You Even After You Take Them Off

Anyone who has worn high heels, or has even simply seen a person in high heels, knows that the foot is definitely not in its usual position in that kind of shoe – walking is more difficult and forget about even trying to run in high heels. Researchers from Manchester Metropolitan University and the University of Vienna wanted to investigate if frequent, long term use of high heels caused lasting changes in the calf, in addition to the normal discomfort experienced by high heel wearers. Previous studies have shown that muscles that are regularly used in unusual ways will often adjust to this new scenario to maintain functionality. These researchers, more specifically, investigated whether the regular wearing of high heels would result in physiological changes to the calf (gastrocnemius) muscle and Achilles’ tendon, and if these changes would then affect the normal functioning of the calf and ankle. In order to determine if and what changes occur, the researchers observed a group of women who regularly wore high heels and a control group who did not to compare their calves and ankles.

two women walking in stillettos
Modified Image by StockSnap on Pixabay

The calf muscle and Achilles’ tendon make up the top and bottom of the rear of the calf respectively. They play a crucial role in controlling ankle motion and in general mobility. Dimensions of the muscles, including length, were measured using ultrasound, and the cross sectional areas of the tendons were measured using MRI imaging. The torque and motion of the ankle were measured by an isokinetic dynamometer. From these values, the researches could determine other important characteristics of the tendon such as the force on it, the strain it experienced, the stiffness, and the modulus of elasticity. The strain value indicates how much the tendon is stretched from its relaxed position since it is the ratio of the change in length to the original length. The stiffness is the ratio of the force experienced to the amount of length change the tendon experienced. The modulus of elasticity, or Young’s modulus, is the ratio of how much force per area the tendon experiences to the strain.

muscles and tendons in the calf and ankle
Modified Image on Smart Servier Medical Art

MRI image of the side of two ankles with one having the foot on a wedge mimicking wearing high heels and one having the foot flat on the ground
From Csapo, Maganaris, Seynnes, and Narici, Journal of Experimental Biology 2010

 

The results of their analysis showed that people who regularly wore high heels had a resting ankle position that made the foot further from perpendicular with the leg than that of someone who did not regularly wear high heels. Additionally, generally the calf muscles of high heel wearers were shorter and the stiffnesses of their Achilles’ tendons were higher due to greater cross sectional areas of the tendons. The maximum strain in the Achilles’ tendon was lower in high heel wearers because of the reduction in length. However, no significant difference in the Young’s modulus of the tendon was observed. Similar torque-angle relationships were observed between the two study groups, so the researchers inferred that the body must have compensated for this new positioning. Additionally, these results explain the observation that high heel wearers had a reduced active range of motion in their ankles because of shorter, stiffer muscles and tendons. What the new normal ankle position means for regular high heel wearers is that their bodies are adjusting to shifts in gait, center of mass, and ground reaction forces if they wear high heels very often. The researchers infer that this physical change to the calf can also account for the discomfort women who regularly wear high heels experience when switching to flat shoes.

For additional discussion of this topic, take a look at Discover Magazine.