Elsevier

Gait & Posture

Volume 62, May 2018, Pages 366-371
Gait & Posture

Full length article
Which is the best predictor of excessive hip internal rotation in women with patellofemoral pain: Rearfoot eversion or hip muscle strength? Exploring subgroups

https://doi.org/10.1016/j.gaitpost.2018.03.037Get rights and content

Highlights

  • Concentric hip abductor strength predicts hip internal rotation in women with PFP.

  • Rearfoot eversion predict hip rotation only in excessive rearfoot eversion subgroup.

  • Excessive rearfoot eversion was found in 48% of women with PFP.

Abstract

Background

Patellofemoral pain (PFP) has been linked to increased patellofemoral joint stress as a result of excessive hip internal rotation. Lower hip strength and/or excessive rearfoot eversion have been used to explain such altered movement pattern; however, it is unknown which one is the best predictor of excessive hip internal rotation.

Research question

To investigate if peak rearfoot eversion and/or peak concentric hip abductor strength can predict peak hip internal rotation during stair ascent in women with PFP.

Methods

This cross-sectional study included thirty-seven women with PFP which underwent three-dimensional kinematic analysis during stair ascent and hip abductor strength analysis in an isokinetic dynamometer. A forced entry linear regression model analysis was carried out to determine which independent variables present the best capability to predict the hip internal rotation.

Results

Peak concentric hip abductor strength significantly predicted peak hip internal rotation during stair ascent (R2 = 0.27, p = 0.001). Peak rearfoot eversion did not predict peak hip internal rotation during stair ascent (R2 < 0.01, p = 0.62). A Post-hoc analysis was conducted to explore if a subgroup with excessive rearfoot eversion would predict hip internal rotation. Based on a previous reported cut-off point, 48.6% of the participants were classified as excessive rearfoot eversion. For the subgroup with excessive rearfoot eversion, peak concentric hip abductor strength and peak rearfoot eversion significantly predicted peak hip internal rotation during stair ascent (R2 = 0.26, p = 0.02; R2 = 0.42, p = 0.003, respectively). For non-excessive rearfoot eversion subgroup, peak concentric hip abductor strength significantly predicted peak hip internal rotation during stair ascent (R2 = 0.53; p < 0.001); and peak rearfoot eversion did not (R2 = 0.01; p = 0.65).

Significance

Findings indicate that hip muscle strength seems to be related with hip internal rotation in all women with PFP. Rearfoot eversion seems to be related with hip internal rotation only in a subgroup with excessive rearfoot eversion.

Introduction

Patellofemoral pain (PFP) is a common complaint amongst sports medicine clinics, accounting for 25–40% of all knee injuries [1]. It has been reported that women are more likely to experience this condition than men [2]. Clinically, individuals with PFP report limitations in activities that load the patellofemoral joint (PFJ) during weight bearing on a flexed knee [3], especially ascending stairs [4]. Furthermore, the impact of PFP as a medical issue is highlighted by evidence suggesting a chronic and recurrent nature of pain, persisting for many years with unfavorable outcomes after rehabilitation [5].

The source of pain in individuals with PFP remains unclear [3]. However, the most recent consensus statement from the 4th international PFP retreat proposed a pathomechanical model in which the development of PFP is associated with increased PFJ stress. One of the theories indicate excessive hip internal rotation during weight bearing activities as a possible source of increased PFJ stress [[6], [7], [8]]. There are two well-known theoretical models which attempt to explain the cause of excessive hip internal rotation in women with PFP [[9], [10]]. One assumes that the hip joint depends on hip muscles to provide dynamic stability and control the movement of the femur, therefore, reduced hip strength may lead to a poor hip control and result in an excessive hip internal rotation [9]. Lower isometric, concentric and eccentric hip abductor strength have been reported in women with PFP [[11], [12], [13]]. Specifically, lower concentric hip abductor strength may be associated with excessive hip internal rotation during stair ascent. In this activity, predominantly concentric contractions of hip abductors are required to control the hip movement [[14], [15]]. Another theoretical model assumes that excessive rearfoot eversion during the stance phase of gait [16] or stair ascent [4] may result in excessive hip internal rotation due to joint coupling [10].

Considering the need to reduce PFJ stress, knowing the mechanism that is more associated with hip internal rotation could help clinicians to identify the best treatment strategy to individuals with PFP. For instance, if the lower hip abductor strength is more associated with hip internal rotation, strengthening the hip abductor muscles could be an option to avoid increased PFJ stress in women with PFP. On the other hand, if the excessive rearfoot eversion is more associated, foot orthoses prescription could be also performed in order to avoid the increased PFJ stress [17].

In this context, the aim of this study was: (i) to investigate if the peak rearfoot eversion during stair ascent and/or the peak concentric abductor muscle strength can predict peak hip internal rotation during stair ascent in women with PFP.

Section snippets

Participants

Thirty-seven women with PFP aged 18 to 35 years were recruited between September 2016 and May 2017 via advertisements at fitness centers, public places for physical activity and social medias. The study was approved by the Local Human Ethics Committee, and all participants provided written informed consent. The diagnostic criteria for PFP is listed in Table 1.

Procedures

Demographic data (age, body mass and height) were collected prior to testing. All participants were asked to rate their worst knee pain

Results

Descriptive values of participant’s demographics, self-reported measures of pain, function and duration of symptoms, kinematics and strength variables are presented in Table 2.

Peak concentric hip abductor strength significantly predicted peak hip internal rotation during stair ascent (R2 = 0.27, B = −0.05, 95%CI −0.08 to −0.02, p = 0.001). Peak rearfoot eversion did not predict peak hip internal rotation during stair ascent (R2 < 0.01, B = 0.12, 95%CI −0.40 to 0.65, p = 0.62) (Fig. 2).

Discussion

Our findings indicate that only peak concentric abductor strength explained significantly the variance of peak hip internal rotation during stair ascent in all women with PFP. However, after splitting the participants into subgroups regarding excessive or non-excessive rearfoot eversion, we found that in the excessive rearfoot eversion subgroup, both independent variables (peak concentric abductor strength and peak rearfoot eversion) significantly predicted the variance of peak hip internal

Conclusion

In general, peak concentric hip abductor strength and not peak rearfoot eversion predicted peak hip internal rotation while ascending stairs. However, in a subgroup with only women with excessive rearfoot eversion (48.6%), peak concentric hip abductor strength and peak rearfoot eversion predicted the peak hip internal rotation while ascending stairs.

Conflict of interest

No author has any financial or personal relationship with people or organizations that could inappropriately influence this work.

Acknowledgments

To São Paulo Research Foundation (FAPESP) for a grant (2014/24939-7) and a scholarship (2016/02357-1). The financial sponsors played no role in the design, execution, analysis and interpretation of data, or writing of the study.

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  • Cited by (0)

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    Present address: La Trobe University, School of Allied Health, Bundoora, Victoria, Australia.

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