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Brazilian Patellofemoral Pain Research Group

The Brazilian Patellofemoral Pain Research Group (BPFPRG), is a research group composed by researchers and students from the University of Sao Paulo State (UNESP) – Presidente Prudente, Brazil. We have collaborations with other institutions in Brazil, Australia, USA and Denmark.

We create this page aiming spread information related to patellofemoral pain, which could contribute to clinical practice and general population with knee pain. Moreover, we aim to promote the translation of research into clinical practice.

Below you will find our contributions in a plain language:

WHICH IS THE BEST PREDICTOR OF EXCESSIVE HIP INTERNAL ROTATION IN WOMEN WITH PATELLOFEMORAL PAIN: REARFOOT EVERSION OR HIP MUSCLE STRENGTH?

The development of PFP is associated with increased PFJ stress as a consequence of excessive hip internal rotation. In this way, both reduced hip strength and excessive rearfoot eversion may result in excessive hip internal rotation. However, recent studies have been proposed the existence of possible subgroups in PFP regarding different biomechanical alterations, such as excessive rearfoot eversion, which indicate that only a portion of the PFP population may present this alteration. Therefore, this study performed by our research group aimed to investigate if the rearfoot eversion during stair ascent and/or the hip abductor muscle strength can predict the hip internal rotation during stair ascent in (i) all participants with PFP and (ii) in subgroups of women with PFP with excessive rearfoot eversion and non-excessive rearfoot eversion.

WHAT DO WE FOUND? For all participants with PFP, only hip muscle strength significantly predicted (27%) hip internal rotation during stair ascent. Considering previously published cut-off points, 48.6% of women with PFP were classified as excessive rearfoot eversion subgroup. For this subgroup, both hip muscle strength and rearfoot eversion significantly predicted hip internal rotation (26% and 42%, respectively). For non-excessive rearfoot eversion subgroup, only hip muscle strength significantly predicted (53%) hip internal rotation.

TAKE HOME MESSAGE Impaired hip strength seems to be a problem in all patients, while excessive rearfoot eversion is a problem in just a subgroup of patients with PFP.

FOR MORE INFORMATION, SEE THE TEXT: Ferreira et al. Which is the best predictor of excessive hip internal rotation in women with patellofemoral pain: Rearfoot eversion or hip muscle strength? Exploring subgroups. Gait & Posture 2018; 62: 366-371.

INCREASE IN VERTICAL GROUND REACTION FORCE LOADING RATE AND PAIN LEVEL IN WOMEN WITH PATELLOFEMORAL PAIN AFTER A PATELLOFEMORAL JOINT LOADING PROTOCOL

During the stance phase of the gait, the Vertical Ground Reaction Force (VGRF) guide the forces that are transmitted and absorbed throughout the lower limb of the human body. The body tissues adapt to the forces applied. When exposed to forces in short periods of time, such as forces produced quickly (i.e. higher loading rates), inadequate force absorption may lead damage lower limb joints, including the patellofemoral joint.

Women with Patellofemoral Pain (PFP) use compensatory movements in order reduce pain during functional tasks (such as stair negotiation). This behavior may compromise force absorption and increase the rapid application of forces during stance phase of the gait, consequently increasing the loading rate of the VGRF.

This study of our laboratory aimed to investigate the immediate effect of a patellofemoral joint (PFJ) loading protocol in the level of pain and VGRF loading rate in women with PFP during stair negotiation.

HOW WAS THE PROTOCOL PERFORMED?

34 women with PFP were randomized to 2 conditions:

Condition 1 (Pre Protocol): as soon as they arrived at the laboratory all participants were asked to rate their knee pain, indicating the amount of pain they were feeling at the moment. Then, each participant was asked to perform five repetitions of stair ascent and descent.

Condition 2 (Post Protocol): Participants were asked to perform a PFJ loading protocol*, in order to load their PFJ. Then, each participant was asked to perform five repetitions of stair ascent and descent.

PFJ loading protocol: 15 repetitions of stair negotiation with 35% external load of the subject's body mass carried in a backpack.

WHAT DO WE FOUND?

• After PFJ loading protocol: knee pain increased in women with PFP;

• After PFJ loading protocol: the VGRF loading rate increased in women with PFP;

• After PFJ loading protocol: the stance time decreased during stair negotiation.

WHAT DOES THAT MEAN?

The application of high forces and the inadequate absorption (i.e. higher VGRF loading rates), can compromise the lower limb joints and lead to increase of knee pain during functional tasks in women with PFP.

TAKE HOME MESSAGE:

Increase in pain after PFJ loading protocol was associated with the increase in VGRF loading rates in women with PFP.

FOR MORE INFORMATION, SEE THE TEXT: BRIANI, R. V. et al. Association between increase in vertical ground reaction force loading rate and pain level in women with patellofemoral pain after a patellofemoral joint loading protocol. Knee, 2018.

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