Dr Kylie Tucker

Funded by: Jointly funded by Arthritis South Australia and Arthritis Western Australia
Recipient: Dr Kylie Tucker
Intended Department School of Biomedical Sciences, Faculty of Medecine- The University of Queensland
Project: Balancing Muscle force  and persistent knee pain in adolescents


We determined that the balance of muscle force did not differ between adolescents with and without PFP, at any contraction level during either the isometric contractions or during the wall squat tasks. This means that our first hypothesis was not supported. There was no evidence of a difference in the way our adolescents with PFP controlled the force of their thigh muscles compared to the control population.

However, an imbalance of muscle force was observed between the vastus lateralis (VL) and medialis muscle (VM) across all participants during the seated task, which is interesting. In both groups, and at all contraction levels, VL contributed approximately 66% of the total muscle force produced by VL+VM, during the ometric knee extension tasks. In contrast, during the wall-squat VL contributed approximately 53% of total muscle force produced by VL+VM. As such, the force seems to be a much more balanced between the muscles in this wall-squat task. Taken together, these results suggest that the contribution of VL to the total force is different, between the seated and wall squat task.

In conclusion: (i) we provide no evidence that the (im)balance of VL and VM muscle forces differ  between adolescents with PFP compared to controls. This may reflect a relatively short duration of disease in our adolescent participants. It remains important to consider the same outcomes in adults with PFP and patellofemoral osteoarthritis. (ii) The wall squat appears to balance the force generation of VM and VL compared to the isometric knee extension task, irrespective of if force is guided through the toes or heels. This has significant clinical implications, as it provides evidence that the way we activate our muscles is altered simply by the type of task being performed.

As this project was partially funded by 2 Arthritis Australia grants, it remains ongoing. The data is in the final stages of analysis, and we will update this section on completion of the additional grant funding. In addition, the participants in our study are now participating in another adolescent patellofemoral pain study, being led by CI-Dr Nat Collins, at UQ. The findings have led to new research questions related to our knee pain population(s). In particular, we do want to continue this work in people with longer duration of pain of muscle activation used during the test tasks. Muscle activation was recorded during (i) seated isometric knee extension tasks (i.e the knee joint angle does not change during these contractions) performed at low, and moderate levels of contraction with the knee at 60o; and (ii) during wall-squats (i.e performing a squat, with the participants back supported by a wall) with force, including body weight, transferred through the toes or heels of our participants.