Knock Kneed Runner

Running Knock Kneed – The HADD Hip

As a physical therapist who specializes in the treatment of runners, I am frequently asked the question, “what changes can I make to my running technique to reduce my risk of injury?” Fortunately, the answers to this question are increasingly being researched with biomechanical running studies. Abnormal hip and knee postures during running are associated with multiple running injuries.1,3A common running biomechanical flaw is excessive hip adduction (HADD) or “knock-kneed” posture.

The HADD Hip

Runner with excessive hip adduction of knock kneed posture

During the weight bearing phase of running, hip adduction angles greater than 20 degrees are associated with iliotibial band syndrome, tibial stress fractures and patellofemoral pain.2 Knock-kneed posture usually peaks as the thighs pass each other during the running cycle. Chafing along the inner thigh, pain on the inner side of the weight bearing leg, and whipping the leg around during the swing phase of gait are common signs and symptoms of excessive HADD. Often a runner will be shocked at this abnormal knee and hip posture when they view their race photos. Look for pictures taken towards the end of the race where fatigue amplifies one’s running flaws.

The most effective method of assessing HADD with running is to undergo a video gait analysis. It can be very difficult to observe knee movements without slowing down or freezing videos of runners because the motion occurs so quickly. A professional video analysis will utilize specialized software and video equipment combined with anatomical markers to measure joint angles.

A rough idea of peak HADD angle can be observed utilizing a hand held video camera or even a smart phone with video capabilities. From the posterior view, measure the angle between a line drawn along the waist band and a line bisecting the femur when the legs are even with each other during mid-stance of the running cycle. The Fig. 1 demonstrates a picture captured from a gait analysis. Measurements can also be taken from the anterior position as in Video 2. Angles near or greater than 20 degrees are commonly accepted be excessive.

The HADD Hip

Anterior view of ultramarathoner with excessive hip adduction

Excessive hip adduction has several potential biomechanical causes. Weakness of the hip abductors and external rotators is the most commonly accepted.2 The main hip abductors and external rotators are the gluteus maximus and medius muscles.

Excessive foot pronation is another biomechanical trait that may contribute to excessive hip adduction.4 In some cases, as the arch of the foot collapses, the tibia and femur follow the foot as it moves inward leading to increased hip adduction angles. A “ground up” approach utilizes foot orthotics and/or motion control shoes to prevent knock knee postures.

Habitual postures can promote asymmetrical hip strength. Hiking a hip while standing, crossing one leg over the other, and holding a child on one hip more than another are all examples of postures that may lead to weakness of the hip abductors and become more apparent with running.

Iliotibial band friction syndrome is one the main injuries associates with runners that have excessive HADD.7 The excessive hip adduction angles lead to increased tension over the outside structures of the knee and hip. These same mechanics can lead to patellofemoral syndrome1, hip strains and sacroiliac/lumbar spine sprains.

While the research suggests that a comprehensive hip strengthening program appears to decrease pain in runners with iliotibial band friction syndrome and patellofemoral pain, 5,1 studies do not demonstrate an associated decrease in hip adduction. In other words, if a runner with knee pain and excessive HADD strengthens their hip, while knee symptoms improve, their abnormal postures may not actually change.

Studies are however, demonstrating that altering training technique may result in more controlled hip postures.6 Running with a higher cadence may actually decrease peak hip adduction angles because the limb is in contact with the ground for less time, providing less opportunity for the knee and lower limb to collapse inward. For a review of cadence training go to: /locations/idaho/treasure-valley-boise/running-cadence-training

In summary, hip weakness appears to be the most common cause for a knock kneed running posture. This posture is one of the main contributors to knee injuries such as patellofemoral pain and iliotibial band syndrome. While strengthening the hip abductors may decrease your symptoms it may not actually change the HADD angle significantly. Hip strengthening and running technique training done in combination seem to be the most effective way to manage this condition. Contact a physical therapist for a more detailed assessment of running posture and biomechanics.


  1. Powers CM. The influence of abnormal hip mechanics on knee injury: a biomechani­cal perspective. J Orthop Sports Phys Ther. 2010;40:42-51.
  2. Willy R.W.; Davis I.S, The Effect of a Hip-Strengthening Program on Mechanics During Running and During a Single-Leg Squat. J Orthop Sports Phys Ther 2011;41(9):625-632, Epub 12 July 2011
  3. Niemuth, P. E.; Johnson, R. J.; Myers, M. J.; Thieman, T. J., Hip Muscle Weakness and Overuse Injuries in Recreational Runners. Clinical Journal of Sports Medicine 2005, (15), 14-21.
  4. McClay I, Manal K. A comparison of three dimensional lower extremity kinematics during running between excessive pronators and normals. Clin Biomech (Bristol, Avon). 1998;13:195-203.
  5. Fredericson M, Cookingham CL, Chaudhari AM, Dowdell BC, Oestreicher N, Sahrmann SA. Hip abductor weakness in distance runners with iliotibial band syndrome. Clin J Sport Med. 2000;10:169-175.
  6. Thein-Nissenbaum, PT, Dsc, SCS ATC et al. Low Back and Hip Pain in a Postpartum Runner: Applying Ultrasound Imaging and Running Analysis J Orthop Sports Phys Ther 2012;42(7):615-624
  7. Ferber R, Davis I, Hamil J, Pollard CD. Prospecitve biomechanical investigation of iliotibial band syndrome in competitive female runners [abstract]. Med Sci Sports Exerc. 2003;35:S91.