Functional Knee Valgus

Functional Knee Valgus in a Barbell Squat 

Download a pdf copy here.

One of the most common lower leg dysfunction we see in athletes, particularly general population is functional knee valgus, or better referred to as the knees caving in during a squat pattern movement. Often you hear coach’s giving the cue “drive your knees out!” at first glance this makes sense, however this is lower order thinking and does not solve the lower leg dysfunction in the long run. After this case study, you will hopefully see that simply cueing to drive the knees out is not enough. We must look deeper into this problem to make long term lasting changes in proper movement pattern.

 

This case study will discuss Things that could have potentially caused this lower leg dysfunction to appear. Through analysis on Dart Fish and the overhead squat assessment taught by Brent Brookbush of the Brookbush institute we will examine the Acetabular femoral joint (AFJ), Tibiofemoral joint (TFJ), and the Talocrural joint (TJ). Through this we will find musculature that is short and overactive, long and underactive, and long and overactive. Once we identify this through thorough analysis we can the better prescribe corrective exercises and manual release and mobility drills to clear up this lower leg dysfunction. We will Examine five key positions in a barbell back squat. The five positions will be hip flexion, knee flexion, Dorsiflexion, Knee Extension, and hip extension.

 

Movements Analysis

 

The athlete may not currently be experiencing pain caused by the functional knee valgus, however the athlete is losing out on performance and running the risk of overuse and injury to the Medial side of the knee due to the medial displacement caused by the knees bowing in (Brookbush, 2017). This movement dysfunction may only be present during loaded squatting movements. A major contributor to this problem is caused by a lack of isolated hip extension activity’s as well very minimal training of the Femoral external rotators such as the Gluteus Maximus and the Gluteus Minimis outside of her main barbell movements causing them to lose tone and become long and underactive(firing late or weak).

 

Below is the Dartfish Link Highlighting the five key positions and the associated movement dysfunction.

http://dartfi.sh/rTZ2TNVzKy0

 

Key position one: Hip Flexion (Eccentric Phase)

Hip-Flexion1

Table 1: Musculature acting on the hip joint.

Muscle Origin Insertion Action Plane of Motion
Iliacus Inner surface of Illium Lesser trochanter of femur Hip flexion, External rotation of hip, anterior pelvic rotation Sagittal, Transverse
Psoas major and minor Lower borders of transverse process L1-L5, T-12 Lesser trochanter of femur, Pectineal line of pubis Hip flexion, flexion of lumbar spine, external rotation of hip, Sagittal, Transverse
Rectus Femoris Anterior inferior iliac spine of the Illium Superior aspect of the patella and patella tendon of the tibial tuberosity Hip flexion, knee extension Sagittal
Sartorius Anterior superior iliac alpine Anterior medial surface of tibia just below condyle Hip flexion, knee flexion, external rotation of femur when knee is bent, hip abduction Sagittal, transverse, frontal
Pectineus Superior ramus of pubis Pectineal line of femur Adduct the hip, internally rotate hip joint Sagittal, frontal, transverse
Adductor Brevis Inferior ramus of pubis Pectineal line and medial lip of linea aspera Adduct the hip, internally rotate the hip, flex hip, internally rotate flexed knee Frontal, transverse, sagittal
Adductor Longus Pubic tubercle Medial lip of linea aspera Adduct the hip, internally rotate the hip, flex hip, internally rotate flexed knee Frontal, transverse, sagittal
Adductor Magnus Inferior ramus of the pubis, ramus of ischium and ischial tuberosity Medial lip of linea aspera and adductor tubercle Adduct the hip, internally rotate the hip, flex hip, internally rotate flexed knee Frontal, transverse, sagittal
Gracilis Inferior ramus of pubis Proximal, medial shaft of tibia at pes anserinus tendon Flex knee, internally rotate flexed knee, hip adduction, internal rotation of hip Frontal, transverse, sagittal
Semitendinosus Ischial tuberosity Upper anterior medial surface of tibia Knee flexion, hip extension, posterior pelvic rotation, internal rotation of hip, internal rotation of flexed knee Sagittal, transverse
Semimembranosus Ischial tuberosity Posteromedial surface of the medial tibial condyle Knee flexion, hip extension, posterior pelvic rotation, internal rotation of hip, internal rotation of flexed knee Sagittal, Transverse
Biceps Femoris Long head: ischial tuberosity

Short head: lower half of linea aspera

Head of fibula and lateral condyle of tibia Knee flexion, extension of hip, posterior pelvic rotation, external rotation of hip, external rotation of knee Sagittal, Transverse
Gluteus Maximus Coccyx, edge of sacrum, posterior iliac crest Iliotibial tract and gluteal tuberosity Hip extension, external rotation of hip, abduct the hip, lower fibers assist in adduction Sagittal, Transverse, Frontal
Gluteus Medius Lateral surface of Illium just below crest Posterior and middle surfaces of the greater trochanter of femur Abduction of hip, flex hip internally rotate hip, extend the hip, externally rotate the hip Frontal, Transverse, Sagittal
Gluteus Minimis Lateral surface of Illium Anterior surface of greater trochanter of the femur Abduct, internally rotate the hip, Flex hip Frontal, transverse, sagittal
Tensor Fasciae Late Anterior iliac crest, and surface of the Illium just below crest Iliotibial tract Flex hip, internally rotate hip, Abduct the hip Frontal, Sagittal, Transverse
Piriformis Anterior surface of sacrum Superior aspect of greater trochanter External rotation of hip, Abduction of hip Transverse
Gemellus inferior & superior Inferior: ischial tuberosity

Superior: ischial spine

Inferior and superior: medial surface of greater trochanter External rotation of hip Transverse
Obturator internus obturator membrane and inferior surface of obturator foramen Medial surface of greater trochanter External rotation of hip Transverse
Obturator Externus Rami of pubis and ischium Trochanteric fossa of femur External rotation of hip Transverse
Quadratus Femoris Lateral border of ischial tuberosity intertrochanteric crest External rotation of hip Transverse

 

 

The first phase of hip flexion in the eccentric phase of the loaded barbell back squat gives very little insight as to what musculature is causing the knee valgus. The hip extensors, external rotators, internal rotators are eccentrically decelerating the body so the athlete can support the weight in a controlled manner during her descent. In this phase of the squat the athlete is in a good position.

What I am looking for is upright torso, knees tracking over the second toe (not bowing in or out), feet remain pointing forward they do not go out, and there is no inversion or eversion of the feet.  At this point in the movement the transverse abdominis, Rectus abdominis, internal and external oblique’s, multifidi’s, and rotators are all in an isometric contraction to keep the torso stable.

Table 1 list’s all the muscles that act on the hip joint. The main muscles that are involved in eccentric deceleration are Gluteus Maximus, Biceps Femoris long and short head, Semimembranosus, Semitendinosus, Adductor Magnus posterior fibers, Gluteus medius posterior fibers, rectus Femoris, vastus lateralis, vastus medialus, vastus intermedius, Sartorius, and Gastrocnemius.

 

Key position 2: Knee flexion (Eccentric phase)

Knee-Flexion1

Table 1.1: Musculature acting on the knee joint.

Muscle Origin Insertion Action Plane of motion
Biceps Femoris Long head: ischial tuberosity

Short head: lower half of linea aspera

Head of fibula and lateral condyle of tibia Knee flexion, extension of hip, posterior pelvic rotation, external rotation of hip, external rotation of knee Sagittal, Transverse
Semitendinosus Ischial tuberosity Upper anterior medial surface of tibia Knee flexion, hip extension, posterior pelvic rotation, internal rotation of hip, internal rotation of flexed knee Sagittal, transverse
Semimbranosus Ischial tuberosity Posteromedial surface of the medial tibial condyle Knee flexion, hip extension, posterior pelvic rotation, internal rotation of hip, internal rotation of flexed knee Sagittal, Transverse
Gracilis Inferior ramus of pubis Proximal, medial shaft of tibia at pes anserinus tendon Flex knee, internally rotate flexed knee, hip adduction, internal rotation of hip Frontal, transverse, sagittal
Sartorius Anterior superior iliac alpine Anterior medial surface of tibia just below condyle Hip flexion, knee flexion, external rotation of femur when knee is bent, hip abduction Sagittal, transverse, frontal
Gastrocnemius Condyles of the femur, posterior surfaces Calcaneus Knee flexion, plantar flex Talocrural joint Sagittal
Popliteus Lateral condyle of femur Proximal, posterior aspect of tibia Internal rotation of flexed knee, knee flexion Sagittal, Transverse
Plantaris Lateral supracondylar line of femur Calcaneus Plantar flexion, Weak flexion of knee Sagittal

 

Much like key position 1, in this phase of the squat the athlete is not showing any signs or symptoms of lower leg dysfunction. This is because the muscles that play a large role in causing functional knee valgus are acting as eccentric decelerators, the muscles that are long and underactive causing a loss in muscle tone leading to improper firing pattern are also either eccentrically decelerating the athlete or not truly active. However, although not visibly present in this phase, loss of Dorsiflexion is a major contributor to lower leg dysfunction, causing tibial internal rotation, eversion of the foot, and alters muscle recruitment patterns (Brookbush, 2017). It may not be visible now, but it is likely there is dorsiflexion restriction taking place, this will be looked at in more detail in Key position3.

Key position 3: Dorsiflexion (Eccentric phase)

DorsiFlexion

Table 1.2: Musculature acting on the ankle joint.

Muscle Origin Insertion Action Plane of motion
Tibialis Anterior Lateral condyle of tibia; proximal lateral surface of tibia Medial cuneiform and base of first metatarsal Dorsiflexion, inversion of foot Sagittal, Frontal
Extensor Digitorum longus Lateral condyle of tibia; proximal lateral surface of tibia Middle and distal phalanges of second through fifth toe Dorsiflexion of ankle, eversion of foot, Extension of four lesser toes Sagittal, Frontal
Extensor halluces longus Middle anterior surface of fibula and interosseous membrane Distal phalanx of first toe Dorsiflexion, Weak inversion, Extension of great toe Sagittal, Frontal

 

Much like the previous two positions the Tibialis Anterior, Extensor Digitorum longus, and the Extensor halluces longs are not currently active, that is because the ankle joint is passively in dorsiflexion, the body is not actively dorsi flexing. The Gastrocnemius, soleus, tibialis posterior, peroneus longus, peroneus brevis, flexor digitorum longus, flexor halluces longus, and Plantaris (planter flexors Antagonist on dorsiflexion) are acting as eccentric decelerators. The plantar flexors play a larger role in body control in this phase than the dorsiflexors even though the ankle is in dorsi flexion, they are still acting passively only lengthening because the weight is pushing the athletes body down. Although still not present, the athlete may be experiencing loss of dorsiflexion. Loss of Dorsi flexion can be caused by Long and underactive Tibialis anterior, tibialis posterior, Gracilis, popliteus. It is also caused by Short and overactive Gastrocnemius, Soleus, Fibularis, flexor halluces longus, flexor digitorum longus. A loss in dorsiflexion would decrease the optimal range of motion of 15-20 degrees causing the body to compensate at the ankle by causing inversion or eversion of the feet, or the knee joint causing knee valgus or Varus (Knees bowing out).

 

Key position 4: Knee extension (Concentric phase)

knees-bow-in-eversion-of-foot  knees-extension

 

Table 1.3: Musculature acting knee extension.

Muscle Origin Insertion Action Plane of motion
Rectus Femoris Anterior inferior iliac spine of Illium and groove above acetabulum Superior aspect of the patella and patellar tendon to tibial tuberosity Knee extension, Hip flexion, Anterior pelvic rotation Sagittal
Vastus lateralis Intertrochanteric line, anterior and inferior borders of greater trochanter, gluteal tuberosity, upper half of linea aspera Lateral border of patella and patellar tendon to tibial tuberosity Knee extension Sagittal
Vastus medialus Whole length of linea aspera and medial condyle ridge Medial half of upper border of patella and patellar tendon to tibial tuberosity Knee extension Sagittal
Vastus intermedius Upper 2/3 of anterior surface of femur Upper border of patella and patellar tendon to tibial tuberosity Knee extension Sagittal

 

As seen above the concentric phase of the squat is where the athlete is showing the presence of a lower leg dysfunction. The athlete’s knees are caving in (functional valgus) and the feet flatten out (Eversion/Pronation). Both lower leg dysfunctions are related to each other as the body functions in a connected kinetic chain. From Brent Brookbush’s overhead squat assessment of the Brookbush institute we can determine what musculature is responsible for the lower leg dysfunction. Functional valgus is caused by Overactive tibial external rotators, Tensor fasciae latae, biceps Femoris short head, and lateral Gastrocnemius. Overactive femoral internal rotators, Tensor fasciae latae, gluteus minimums, and Adductors. Underactive tibial internal rotators, Gracilis, Semitendinosus, semimembranosus, Sartorius, medial gastrocnemius, and vastus medialus. Underactive Femoral external rotators, Gluteus maximus, gluteus medius. The musculature that is overactive is usually short and compensating for the musculature that is underactive and usually long causing them to fire weak or late. In the case of knees bow in the tibia is attempting to externally rotate while the femur is internally rotating causing medial knee displacement (Brookbush, 2017). This dysfunction is a major problem for sports performance and injury prevention. The main concern is the long and underactive gluteus maximus, gluteus medius which is classified as our posterior oblique subsystem. Glute function and hip extension are highly important in activities of daily living and force production. Our glutes being our most powerful hip extensors having them become long and underactive is a problem even if you are not in search of sports performance.

 

Key position 5: Hip Extension (concentric phase)

Hip-Extension-concentric-phase

Table 1.4: Musculature acting on hip extension (concentric phase)

Muscle Origin Insertion Action Plane of motion
Gluteus maximus Coccyx, edge of sacrum, posterior iliac crest Iliotibial tract and gluteal tuberosity Extend hip, externally rotate the hip, abduct the hip, lower fiber adduct hip Sagittal, Transverse, Frontal
Biceps Femoris long head Ischial tuberosity Head of fibula Flex knee, extend hip, externally rotate bent knee, laterally rotate hip joint Sagittal, Transverse
Semitendinosus Ischial tuberosity Proximal, medial shaft of tibia and pes anserinus Flex knee, internally rotate flexed knee, extend hip, tilt pelvis posteriorly Sagittal, Transverse
Semimembranosus Ischial tuberosity Posterior aspect of medial condyle of tibia Flex knee, internally rotate flexed knee, extend hip, tilt pelvis posteriorly Sagittal, Transverse
Adductor Magnus Inferior ramus of the pubis, ramus of ischium and ischial tuberosity Medial lip of linea aspera and adductor tubercle Adduction of hip, internal rotation of hip, assist in hip flexion, Frontal, Transverse, sagittal
Gluteus medius Gluteal surface of Illium, between posterior and anterior gluteal lines Lateral aspect of greater trochanter Hip abduction, flexion and extension of hip, internal and external rotation of hip

 

At this point the hip joint and knee joint are in full extension. The athlete is no longer presenting signs of a lower leg dysfunction. Even though in position 4 the hip extensors fire weak or late at this point they are functioning. The strength curve at this point is at its lowest since the muscles are fully contracted. When assessing an athletes squat mechanics, it is important to focus on the entire movement. Functional knee valgus only occurred in knee extension during the concentric phase of the squat. If you do not asses all phases you may miss out on identifying a postural or movement dysfunction ultimately leading to loss in performance and injury.

 

Functional knee valgus corrective Exercise Techniques

 

In functional knee valgus, the muscles that were identified as short and overactive are the Tensor fasciae latae, Biceps Femoris short head, lateral gastrocnemius, glute minimums, and the adductor complex. Muscles that were identified as long and under active are the Gracilis, Semimbranosus, Semitendinosus, medial gastrocnemius, vastus medialus, gluteus maximus, and Gluteus medius. Muscles that are short and overactive should be manually released and stretched and muscles that are long and underactive should be activated (Brookbush, 2017). For release and stretch you should focus on the Tensor Fasciae latae and the biceps Femoris short head since they play a major role in femoral internal rotation. For activation techniques, you should focus on the gluteus maximus and gluteus medius. This is because they are or most powerful hip extensors and activating them will benefit the athlete beyond just fixing a movement dysfunction.

 

Tensor fasciae latae/hip flexor manual release

http://dartfi.sh/4Af3j7nOOf9

For the TFL release it is important to use a softball or lacrosse ball, a foam roller will not apply enough pressure per square inch. Find a trigger point, you will know you found it because it will be very tender. Remain on that spot for 30 seconds or until the trigger point releases. Repeat on the opposite side. This can be done up to three times on each side.

 

Tensor fasciae latae/hip flexor stretch

http://dartfi.sh/68bgBGyHiZ1

For the TFL hip flexor stretch attach a heavy resistance band to a stable structure, in the video it is attached to a bolted in squat rack. The band should be just lower than hip height. When doing this, it is important to find a stretch by posteriorly tilting your pelvis rather than gaining as much hip extension as possible. The hip only has 10-15 degree extension, any farther and mobility is being gained in other areas of the body. This stretch should be held for 45-60 seconds for up to three times on each side.

 

Biceps Femoris short head manual release

http://dartfi.sh/EHqRei8xG7a

For this manual release, it is important to be on a box and use a softball or lacrosse ball, if not you will not get enough pressure per square inch to gain a release. Place the ball under you lateral lower femur just above the knee. Find a tender spot, once you do slowly extend your knee. You can perform 10-15 knee extensions on each side for up to three sets or until you have achieved a release.

 

Biceps Femoris manual stretch

http://dartfi.sh/XDL5IUbVeVl

For this stretch lay flat on your back pinning both shoulders on the ground, it is highly important that bot shoulders remain on the ground during the duration of this stretch. Flex you knee towards your chest, take your opposite arm and pull your leg just past your midline. Once you are in the position flex and extend your knee while maintaining a hold on your leg with your opposite hand. You can do 10-15 knee extension on each leg for up to three sets.

 

Glute maximus Activation Glute bridge

http://dartfi.sh/WbYNwhUQCV7

For this activation drill lay flat on your back, Shoulders pinned to the ground, knees flexed and feet flat. Your feet should be placed wider than your shoulders in a sumo type stance. Drive your hips up into full extension fully contracting your Glutes, it is important to hold this position at the top for 1-2 seconds. This activation drill can be done for up to 30 reps, and for up to three sets.

 

Glute medius Activation

http://dartfi.sh/b6LCa9K94Ze

For this Activation drill lay on your side on the ground with your hips stacked evenly on top of each other. In a controlled manner abduct and adduct your leg. During this drill, it is highly important to minimize your hips moving anteriorly or posteriorly. Also, do not allow your hips to be flexed they should be in a neutral position. Perform this activation technique for 15-20 reps on each side for up to three sets. This movement can be progressed by adding ankle weights, be sure to start very light and progressively add external resistance.

 

References:

Brookbush, B. (2014, July 28). Exercises to Reduce Knee Valgus During Squatting. Retrieved December 5, 2017, from brentbrookbrush.com

Brookbush, B. (2017, May 23). Lower Extremity Dysfunction (LED). Retrieved December 5, 2017, from Brentbrookbrush.com

Brookbush, B. (2017). Overhead Squat Assessment: Signs of Dysfunction. Retrieved December 5, 2017, from Brentbrookbrush.com

Floyd, R. T., & Thompson, C. W. (2018). Chapter 9. In Manual of structural kinesiology (19th ed., pp. 229-272). New York, NY: McGraw-Hill Education.

Floyd, R. T., & Thompson, C. W. (2018). Chapter 10. In Manual of structural kinesiology (19th ed., pp. 273-293). New York, NY: McGraw-Hill Education.

Floyd, R. T., & Thompson, C. W. (2018). Chapter 11. In Manual of structural kinesiology (19th ed., pp. 293-328). New York, NY: McGraw-Hill Education.

 

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Justin Biays

Justin is the founder and head coach of Dark Horse Performance. He is a former United States Army 11B (infantry). He served 1 tour of duty in Afghanistan, realizing quickly that standard gym routines did not cut it for the duties he was expected to perform. He found his love for "Functional Fitness" returning from Afghanistan, then he decided it was time to try CrossFit. After leaving the Army in 2012 he attended the Metropolitan State University of Denver, where he earned his bachelor’s degree in exercise science with a minor in nutrition.