Elsevier

Clinical Biomechanics

Volume 29, Issue 9, November 2014, Pages 1056-1062
Clinical Biomechanics

The immediate effects of foot orthoses on hip and knee kinematics and muscle activity during a functional step-up task in individuals with patellofemoral pain

https://doi.org/10.1016/j.clinbiomech.2014.08.005Get rights and content

Highlights

  • Orthoses are effective in PFP management however mechanism(s) is poorly understood

  • We explore mechanisms of foot orthoses effects during a stepping task in individuals with PFP

  • Foot orthoses result in immediate changes in hip and knee kinematics

  • Gluteal amplitude is reduced following orthoses application

  • Lower limb muscle onsets are unchanged immediately post orthoses application

Abstract

Background

Evidence shows that anti-pronating foot orthoses improve patellofemoral pain, but there is a paucity of evidence concerning mechanisms. We investigated the immediate effects of prefabricated foot orthoses on (i) hip and knee kinematics; (ii) electromyography variables of vastus medialis oblique, vastus lateralis and gluteus medius during a functional step-up task, and (iii) associated clinical measures.

Methods

Hip muscle activity and kinematics were measured during a step-up task with and without an anti-pronating foot orthoses, in people (n = 20, 9 M, 11 F) with patellofemoral pain. Additionally, we measured knee function, foot posture index, isometric hip abductor and knee extensor strength and weight-bearing ankle dorsiflexion.

Findings

Reduced hip adduction (0.82°, P = 0.01), knee internal rotation (0.46°, P = 0.03), and decreased gluteus medius peak amplitude (0.9 mV, P = 0.043) were observed after ground contact in the ‘with orthoses’ condition. With the addition of orthoses, a more pronated foot posture correlated with earlier vastus medialis oblique onset (r =  0.51, P = 0.02) whilst higher Kujala scores correlated with earlier gluteus medius onset (r = 0.52, P = 0.02).

Interpretation

Although small in magnitude, reductions in hip adduction, knee internal rotation and gluteus medius amplitude observed immediately following orthoses application during a task that commonly aggravates symptoms, offer a potential mechanism for their effectiveness in patellofemoral pain management. Given the potential for cumulative effects of weight bearing repetitions completed with a foot orthoses, for example during repeated stair ascent, the differences are likely to be clinically meaningful.

Introduction

Patellofemoral pain (PFP) is one of the most common presentations in recreationally active and sporting populations (Baquie and Brukner, 1997, Taunton et al., 2002). Of 2429 injury presentations to a sports medicine clinic over a 12 month period, 668 (27.5%) cases affected the knee, with PFP reported to be the most common knee complaint (Baquie and Brukner, 1997). Furthermore, a study of 2002 running injuries over a two-year period in a sports medicine clinic, reported 331 patients (16.5%) were diagnosed with PFP (Taunton et al., 2002). PFP is commonly aggravated by stair ascent and descent, squatting, sitting for long periods and high impact activity such as running (Kujala et al., 1993). Despite its high prevalence and positive short term treatment outcomes (Collins et al., 2008, Crossley et al., 2002), 80% of individuals who complete a rehabilitation programme for PFP still report pain, and 74% report a reduction in physical activity at 5 year follow up (Stathopulu and Baildam, 2003), highlighting the need for more effective management plans to be identified. With the aetiology of PFP widely accepted to be multifactorial in nature (Powers et al., 2012), these poor long-term outcomes may represent a failure to address the specific deficits contributing to the development and persistence of PFP.

Anti-pronating foot orthoses (APFOS) are commonly prescribed to individuals with PFP, and have been reported to effectively reduce pain and improve function (Collins et al., 2008, Eng and Pierrynowski, 1993, Mills et al., 2012a). However the mechanism for their effectiveness is poorly understood (Barton et al., 2010). Tiberio (1987) proposed that excessive sub-talar joint pronation may lead to greater tibial and hip internal rotation, and consequently increased lateral tracking and loading of the patellofemoral joint (PFJ). This proposed kinematic coupling between lower limb segments has been supported by reports that greater peak rearfoot eversion is associated with greater tibial internal rotation during walking in individuals with PFP (Barton et al., 2012). It is proposed the APFOS may prevent these aberrant movement patterns and hence reduce pain associated with PFP (Tiberio, 1987).

Step negotiation was chosen to explore lower limb biomechanics in PFP populations due to higher loading forces reported within the PFJ during this activity (Andriacchi et al., 1980) and patients commonly reporting symptoms with stairs (Kujala et al., 1993). Contrary to previous findings that reported changes in symptomology (Eng and Pierrynowski, 1993), foot and knee (Eng and Pierrynowski, 1994) and hip (Lack et al., 2014) kinematics resulting from foot orthoses, Mills et al. (2012b) reported no significant changes to hip or knee kinematics in individuals with PFP during running with the addition of APFOS (Mills et al., 2012b). The lack of consistent findings between studies potentially highlights the multifactorial nature of the condition, differences in biomechanical response to orthoses during differing tasks, or possibly a delay in the influence of APFOS on kinematic variables in individuals with PFP.

Another proposed mechanism for foot orthoses effectiveness is altered neuromotor control. Nigg et al. (1999) proposed that an orthoses that supports a preferred movement path could minimise muscle activity and reduce fatigue by providing input through the sole (Nigg et al., 1999). Individuals with PFP have been reported to frequently possess altered neuromotor control with delayed onsets of vastus medialis oblique (VMO) (Chester et al., 2008, Lankhorst et al., 2013) and gluteus medius (GMed) (Barton et al., 2013) muscle. Despite these identified deficits and theoretical rationale for foot orthoses to address them, a paucity of research exploring the effects of orthoses on neuromotor variables exists (Mills et al., 2010). Recent studies exploring proximal neuromotor effects of APFOS have reported no immediate changes in gluteal and quadriceps muscle onsets or amplitudes during running in individuals with PFP (Mills et al., 2012b) or during a functional step-up task in asymptomatic individuals (Lack et al., 2013). However, with electromyography (EMG) changes described as being highly variable within a heterogeneous population (Mundermann et al., 2006) and PFP widely regarded as having a multifactorial aetiology (Powers et al., 2012), further work exploring the association of specific EMG changes with clinically applicable measures is clearly warranted.

The primary aim of this study was to explore the immediate effects of prefabricated foot orthoses on (i) hip and knee kinematics; and (ii) electromyography (EMG) variables of VMO, vastus lateralis (VL) and GMed. The secondary aim of this study was to identify clinical measures that may be associated with these changes.

Section snippets

Methods

Symptomatic participants had biomechanical data collected at the knee and hip during a functional step-up task. Clinical measures were obtained prior to testing and subsequently analysed to determine any correlation with changes observed due to orthoses application.

Hip and knee kinematics

A significant reduction in hip (femur relative to pelvis) adduction (0.82°, P = 0.01, SMD 0.86) was observed 200 ms after initial contact with the APFOS in situ (Table 2, Fig. 3). A trend towards reduced hip internal rotation at initial contact (− 1.4°, P = 0.07) was observed with the APFOS. A small but significant reduction in knee (tibia relative to femur) internal rotation (0.46°, P = 0.03, SMD 0.53) was observed 100 ms after initial contact with the APFOS in situ. No significant changes were

Discussion

This study is the first to evaluate the effects of anti-pronating foot orthoses (APFOS) on hip and knee kinematics, and electromyography during a functional step-up task in individuals with PFP. Results indicate a reduction in knee internal rotation (100 ms, 0.46°) and hip adduction (200 ms, 0.82°) with an APFOS after initial contact. Additionally, a reduction in GMed amplitude in the APFOS condition (0.9 mV, P = 0.043) was observed. Although small in magnitude, these biomechanical changes may offer

Conclusion

Anti-pronating foot orthoses used during a step-up task reduced hip adduction and knee internal rotation after initial contact and peak GMed amplitude in individuals with PFP. The small magnitude of these biomechanical changes during high repetition activities may have significant clinical implications and explain potential mechanisms for treatment success of APFOS in PFP populations. This is exploratory research of several biomechanical variables, only a few of which showed significant change,

Acknowledgements

We would like to thank the Private Physiotherapy Education Fund (PPEF) (2652861) for their financial support by funding the researchers' time, and Vasyli UK for the provision of orthoses devices.

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