Posts tagged ankle mobility
Is Lack Of Mobility Or Flexibility A Factor In My Running Injury?

Lower extremity stiffness (“leg stiffness”) describes the resistance the joints and muscles in your lower body will have to movement when your foot contacts the ground during running. Think of your leg as a spring; the more tightly coiled spring will be stiffer, the more loosely coiled will be more deformable. A stiffer leg is associated with less joint movement (less mobility) and increased loads to bones and cartilage whereas a less stiff leg is associated with increased joint motion/mobility and relies more heavily on active muscle contraction to dissipate forces when your foot hits the ground.

 Leg stiffness may be one of many variables that contribute to running related injuries. A recent study of 92 runners {Goodwin:2019bk} identified 4 variables that may allow us to more easily predict leg stiffness with clinical measures versus technical laboratory analysis. Less mobility in the ankle joint, hip and big toe joint along with increased BMI are associated with greater leg stiffness. What is the clinical significance of this for our Boulder runners? For runners suffering from knee pain or stress fractures, reducing leg stiffness by improving the mobility of hip, ankle and foot may reduce joint loading. Conversely, in runners with soft tissue injuries such as Achilles or tibialis posterior tendinopathy, increasing leg stiffness with targeted strengthening exercises to improved stability and control of the joints of the lower extremity may be an important component of rehabilitation.

Contact your physical therapy experts at Mend to learn more about how your mobility may contribute to running injury.

Association Between Ankle Mobility and Knee Alignment

The ankle plays a critical role in the ability of the knee to stay over the foot during functional tasks such as walking, running, and stair climbing.  Under normal conditions the mobility of the ankle allows the leg to move forward over the weight bearing foot.  If this range of motion is limited, the leg moves inward causing the knee to move inside of the weight bearing foot.  This position, known as knee valgus, is a common cause of IT band pain, knee pain, patellofemoral pain, and acute ligamentous and meniscal injuries to the knee.  In our Boulder Physical Therapy practice we find many individuals with knee pain who lack adequate ankle mobility.  A recent review article analyzed the available literature associating this mobility with proximal knee stability.

Lima and colleagues reviewed the available literature on the association between ankle mobility, dorsiflexion, and knee position (Physical Therapy in Sport. 2017).  The authors pooled the results of 17 studies and found an association between ankle mobility and dynamic knee alignment.  In addition, they found measurements of the ankle in weight bearing and non weight bearing were both significant for dynamic knee valgus.  This study lends further support to the importance of examining and treating ankle impairments in patients with knee pain.


Utilizing the Squat to Screen for Ankle Mobility
squat-screening-test-ankle mobility

The role of ankle mobility on injury risk and performance has been previously described in our prior blog posts.  These posts have described the correlation between a lack of mobility at the ankle and knee injuries including patellofemoral knee pain and ACL injury, as well as, ankle sprains and achilles tendonitis.  A lack of ankle mobility has been shown to alter knee and hip biomechanics as well as reduce dynamic ankle stability.  A new article reviews the utility of using squat testing as a screening for ankle mobility.

Rabin and colleagues put 53 healthy participants through weight bearing and non wearing ankle mobility measurements as well as squat testing (J Strength Conditioning Research. 2017).  Athletes were screened with both an overhead and forward arm squat to determine their ability to detect a loss of ankle mobility in participants with limited mobility on ankle measurements.  The authors reported high screening utility (sensitivity 1.0, negative likelihood ratio 0.0) for the overhead squat, but better diagnostic properties in the forward arm squat (specificity .84-.88, positive likelihood ratio 3.49-6.02).  Screening athletes first with the overhead squat followed by the forward arm squat is an easy clinical method of assessing ankle mobility.

The Importance of Ankle Mobility for Proper Knee Mechanics
ankle mobility-stretching-knee-pain-injury

In a previous post, we detailed the latest research on the importance of ankle mobility on knee mechanics.  During weight bearing the shin, tibia, must be able to move forward over the fixed ankle and foot.  Without adequate ankle flexibility and shin moved over the foot to the inside placing the knee at risk of traumatic and overuse injuries.  Conversely, patients with adequate ankle mobility and better able to keep their knee over their foot during a step down test.  Granted, many of these patients may also have hip weakness, but the importance of ankle mobility should not be overlooked.  New research supports the influence of ankle mobility on knee mechanics and stability.

In the Journal of Orthopedic and Sports Physical Therapy authors examined 30 healthy participants as they underwent biomechanical testing in a laboratory (Rabin et al. 2016).  The participants were tested on a step down test and then underwent testing of ankle mobility.  Authors then split the group in two based on either low or high degrees of mobility.  As expected, the group with the least amount of ankle mobility demonstrated less knee stability and more knee movement than the group with better ankle mobility.  Athletes and patients are encouraged to assess and treat limited ankle mobility for improvement in knee stability.


Ankle Mobility and Achilles Tendon Injury

The achilles tendon is a strong, durable structure capable of absorbing and producing large loads as we walk, hike, and run.  When the tendon is overloaded without adequate recovery periods this structure is prone to painful and limiting conditions such as achilles tendonitis and tendinopathy.  One of the important risk factors for achilles injury among athletes and patients is a lack of ankle mobility.  If the ankle is unable to bend adequately during functional movements the achilles is placed under increased load leading to tendon injury.  In our Boulder Physical Therapy practice, we commonly see a loss of ankle mobility among patients with achilles tendon injury.

During our Physical Therapy examination we often see a loss of rear foot or ankle mobility and a compensatory increase in motion at the mid foot or arch (pronation).  A recent study in the journal Clinical Biomechanics confirmed our observations (Chimenti, R. et al. 2016).  The authors assessed individuals with and without achilles tendinopathy to determine their ability to bend their ankle as well as which areas of the ankle and foot where contributing to this movement.  The group with achilles tendinopathy had significantly less ankle mobility than the control group.  Importantly, this group compensated during testing with increased mobility of their arch instead due to an inability to move through the rearfoot.

This study highlights the importance of treating the ankle in patients with achilles tendon injury.  To learn more about how to safely and effectively treat this condition contact your local PT.

Influence of Ankle Mobility on Knee Stability and Control

The step down test is an important Physical Therapy test to determine the ability of our athletes to stabilize their lower extremity in single leg stance.  Proper performance of this test requires adequate strength, balance, control, and mobility in the lower extremity.  Often athletes with lower extremity or spinal pain have a significant asymmetry in their ability to perform the test between their uninvolved and involved extremity.  I often find this test helpful to identify patients with knee pain who are unable to control their knee at foot strike.  Often the knee will travel inward toward the opposite leg with a compensatory pelvic drop (see below).  This indicates a lack of strength and/or poor biomechanics in the kinetic chain.  In addition to motor performance the step down test also offers important information on the ankle's ability to flex.

Ankle dorsiflexion, bending, is a crucial component of an athletes ability to perform.  Inadequate dorsiflexion can lead to poor mechanics up the lower extremity influencing pain patterns throughout the lower quarter.  Often I find restoration of an athlete's ankle dorsiflexion through manual therapy and exercise immediately improves their pain and performance on the step down test.  A recent article in the journal Manual Therapy supports the importance of the ankle on lower quarter control (Bell-Jenje et al. 2016).

The authors assessed 30 healthy females to determine the association between a loss of ankle mobility and the inward movement of the knee on a step down test.  Each participant's ankle mobility was measured and the performed the step down in two conditions: one with the foot flat and one with the heels elevated (see picture).  

Consistent with our clinical findings at Mend, the authors noted athletes with decreased ankle mobility demonstrated greater amounts of knee movement during the first test.  Interestingly, the poor mechanics were immediately improved when the participants performed the second test with the heel elevated.  This study highlights the importance of assessing the ankle in individuals with pain or poor performance on the step down test.