Knee Mechanics

It is important to assess multiple areas of the body when treating knee pain and more specifically patellofemoral pain (PFP).  One major contributor to knee pain is hip strength.  Good hip strength is important to aid in appropriate knee alignment and mechanics.  Another important contributor is foot alignment.  Many individuals with PFP exhibit over pronation of the midfoot/flatfoot.  This will cause the lower leg to turn in and place more stress of the patella on the femur.

But one aspect that I believe needs more consideration is ankle range of motion; specifically ankle dorsiflexion range of motion.


A study by Rabin et al. found that individuals with PFP had less than optimal movement during a lateral step down test and exhibited significantly less ankle dorsiflexion range of motion (4.7° in weight bearing and 5.3° in non-weight bearing) than individuals with optimal movement and without pain.  More specifically, they found that men had a significant difference of 8.5° with non-weight bearing measurements.

Could this limitation in ankle dorsiflexion range of motion be a precursor for maladaptive behavior found at the foot, knee, and hip?  The researchers proposed that the limitation in ankle dorsiflexion will cause less forward movement of the tibia when walking, running, and going up and down stairs.  This may cause excessive compensatory movement of the midfoot, such as over pronation, in order to get the needed range to complete those tasks.  This will also cause the knee to turn and place more force of the patella on the femur.

A recommendation to improve ankle dorsiflexion for people with PFP is to complete a stretch against the wall or counter holding for 30 seconds and completing 2 times.  Use this stretch (presented in the video below) until knee discomfort subsides and a lunge position with the knee on the floor can be tolerated.

A more dynamic lunge stretch (shown in the video below) can be completed to further improve ankle dorsiflexion range of motion.  Hold this position for 5 seconds and complete 20 times.  These motions should be completed on both sides even of you do not have discomfort at both legs.


Limitations of the study:

  1. It was not possible to determine whether limited ankle dorsiflexion range of motion is the cause of abnormal lower quality of movement or a consequence.
  2. The findings are limited to visual assessment of the quality of movement during the lateral step down test.
  3. The subgroup analysis was not preplanned and they completed the analysis only after observing abnormal tendencies in the subjects.
  4. The examiners were not completely blinded to the quality of movement assessment.
  5. The sample of subjects were younger than other populations of people with patellofemoral pain so results should not be generalized to all individuals.

Reference: Rabin A, Kozol Z, Moran U, Efergan A, Geffen Y, Finestone AS. Factors associated with visually assessed quality of movement during a lateral step-down test among individuals with patellofemoral pain. J Orthop Sports Phys Ther. 2014; 44(12): 937-946.