How 2D video motion analysis facilitates problem solving, reflective learning, & identification of novel interventions

The referral of this gentleman in the video below was for an exercise program for chronic right knee pain. The patient and the referring Physician Assistant expressed expectations that an exercise program would help decrease his pain so he could return to playing recreational basketball.

There is ongoing controversy about whether high-intensity quadriceps strengthening exercises for an osteoarthritic knee that has malalignment &/or joint laxity is beneficial. Or conversely, whether aggressive strengthening exercises hasten the progression of the problem here, here, and here.

This individual’s right knee valgus malalignment (knock-kneed) was permanent. The inward deviation of the right knee could not be passively positioned in a neutral or straight alignment. Querying the patient, he reported he had tried weightlifting exercises on the knee, and felt the pain was worse after each weightlifting session.

I told him to stop aggressive strengthening exercises and explained why aggressive strengthening exercises can have side effects or unintended consequences. Repeatedly lifting heavy weights with a maligned knee joint is like repeatedly opening and shutting a door with a loose or poorly aligned door hinge. Either the hinge, the door or both are going to fall apart. The repeated movement is not going to straighten the door hinge or repair the door hinge.

Motion Analysis:

I used 2D slow motion video gait analysis in hopes of identifying potential treatment alternatives to exercise therapy, weight reduction, and joint replacement surgery.

Observing the video gait deviations were identified including:

  • Valgus malalignment of the right knee
  • Valgus thrust movement of the right knee during stance phase
  • Shift of trunk to the right side during stance on the misaligned painful right knee (lateral shift of the center of mass)
  • Varus thrust of the left knee, but he was not complaining of pain in the right knee. There is asymmetrical out-toeing, right greater than left. The more normal degree of toe-out is occurring on the more painful right side (15° relative to the line of the progression).

The valgus malignment of the right knee was permanent. Altering the malignment of the knee would require surgical replacement of the knee joint. He is a suitable candidate for knee joint replacement surgery, but he did not have health insurance.

Appropriate treatments to alter and potentially decrease the magnitude of movement of valgus thrust movement during the stance phase on the right are:

  • A knee unloading brace
  • A varus wedge in the right shoe
  • Use of cane in the hand opposite the painful knee.

The patient has a knee unloading brace which he left in his car. He had a varus wedge in his right shoe. He has a cane which he left in his car.

Possible treatment for the trunk lean to the right may be gait training. There is conflicting evidence on whether gait training to alter gait deviations associated with knee arthritis can be maintained. Reslin Schelhaas and colleagues raise the question of whether to allow individuals to choose their own gait deviation/compensation to manage pain. My assessment was the shift of the trunk to right was an appropriate instinctual gait deviation compensation that we can allow and/or encourage to diminish knee pain. Gait training to eliminate the shift of the trunk to the right would likely result in the adverse event of increasing pain.

I shared with the patient I did not have any additional intervention to offer.

He left frustrated.

I was frustrated.

Reflective Learning

My frustration led me to review the video later in the week to see if I missed something. I was looking for some intervention to offer him that had not already been tried. I felt reviewing the video could facilitate some reflective learning.

I noticed there was a difference in how he walked during the first lap compared to the second lap. On the second lap he used his left hand to nudge his pelvis to the right and propelled his right arm out towards the right.

Why did he automatically walk that way? After pondering I produced a hypothesis that he was shifting his center of mass more to the right to decrease stress and pain in the right knee. A potential hypothesis is if carrying weight is in the hand of the painful side, then pain and gait deviation will decrease.

Novel Intervention:

The gentleman below has chronic right hip pain. His natural gait pattern has gait deviations of excessive lean of the trunk (shift of the center of mass) to the painful right hip side and a slow velocity.

Using a cane in the left hand opposite the painful right hip decreases the trunk lean to the right and decreased pain. This is the standard treatment.

Carrying a weight (a 6 pack) in the hand on the painful right side decreases the trunk lean and decreases the pain. This is not standard treatment. Research by Kerri Graber and colleagues suggests the mechanism that carrying weight in the ipsilateral hand decreases key hip joint forces. Alternatively carrying a bag or purse on the ipsilateral shoulder can achieve comparable results.

Using both a cane in the hand opposite the painful side, and weight in the hand of the painful side decreases the trunk lean, decreases the pain, and increases the velocity.

The first case now has multiple options to manage his right knee pain short of surgical replacement of his knee. Unfortunately, the cluster of options still will not meet his expectation of returning to recreational basketball.

This case series illustrates how 2D video motion analysis can be used:

  • To problem solve whether observed gait deviations:
    • Can be altered
    • Should be altered intervened
    • Should be allowed and encouraged
  • For reflective learning and professional development
  • To learn new things from patients
  • To develop novel interventions

A on demand video webinar exploring this topic is available at Plus by Physiopedia entitled “Indications, Benefits, & Barriers of 2D Motion Analysis

Use this code – “Damien30” for a 30% discount to access this webinar as well as the more than 500 continuing education webinar courses available at Plus by Physiopedia. This is the link with the 30% discount code embedded. 

The information on this website is not intended or implied to be a substitute for professional medical advice, diagnosis, or treatment. You are encouraged to perform additional research regarding any information contained available through this website with other sources and consult with your physician.

Damien Howell Physical Therapy – 804-647-9499 – Fax: 866-879-8591 At-Home, At Office, At Fitness Facility – I come to you, I do home visits


  1. Damien Howell on November 6, 2022 at 4:45 pm

    Here is a link to a video recording of the webinar providing more details on this topic

Leave a Comment

You must be logged in to post a comment.