Obesity and Pronated Foot Type May Increase the Risk of Chronic Plantar Heel Pain: A Matched Case-Control Study

Damien B. Irving; Jill L. Cook; Mark A. Young; Hylton B. Menz

Disclosures

BMC Musculoskelet Disord 

In This Article

Abstract and Introduction

Abstract

Background: Chronic plantar heel pain (CPHP) is one of the most common musculoskeletal disorders of the foot, yet its aetiology is poorly understood. The purpose of this study was to examine the association between CPHP and a number of commonly hypothesised causative factors.
Methods: Eighty participants with CPHP (33 males, 47 females, mean age 52.3 years, S.D. 11.7) were matched by age (± 2 years) and sex to 80 control participants (33 males, 47 females, mean age 51.9 years, S.D. 11.8). The two groups were then compared on body mass index (BMI), foot posture as measured by the Foot Posture Index (FPI), ankle dorsiflexion range of motion (ROM) as measured by the Dorsiflexion Lunge Test, occupational lower limb stress using the Occupational Rating Scale and calf endurance using the Standing Heel Rise Test.
Results: Univariate analysis demonstrated that the CPHP group had significantly greater BMI (29.8 ± 5.4 kg/m2 vs. 27.5 ± 4.9 kg/m2; P < 0.01), a more pronated foot posture (FPI score 2.4 ± 3.3 vs. 1.1 ± 2.3; P < 0.01) and greater ankle dorsiflexion ROM (45.1 ± 7.1° vs. 40.5 ± 6.6°; P < 0.01) than the control group. No difference was identified between the groups for calf endurance or time spent sitting, standing, walking on uneven ground, squatting, climbing or lifting. Multivariate logistic regression revealed that those with CPHP were more likely to be obese (BMI ≥ 30 kg/m2) (OR 2.9, 95% CI 1.4 – 6.1, P < 0.01) and to have a pronated foot posture (FPI ≥ 4) (OR 3.7, 95% CI 1.6 – 8.7, P < 0.01).
Conclusion: Obesity and pronated foot posture are associated with CPHP and may be risk factors for the development of the condition. Decreased ankle dorsiflexion, calf endurance and occupational lower limb stress may not play a role in CPHP.

Background

Chronic plantar heel pain (CPHP) is one of the most common conditions affecting the foot and has been reported to account for 15% of all adult foot complaints requiring professional care.[1] It is usually observed in the 40 to 60 year old age bracket, but has been reported in people from 7 to 85 years and appears to be more common in females.[2] Symptoms typically include pain under the medial heel during weight bearing, especially in the morning and at the beginning of weight-bearing activities.[1,3]

As with many conditions where the true pathology is unclear, CPHP has become a generalised term encompassing a broad spectrum of conditions affecting the heel, including subcalcaneal bursitis, neuritis, plantar fasciitis and subcalcaneal spur.[4,5] However, plantar fasciitis is considered to be the most common cause of pain and the terms are used interchangeably in the literature.[1] Due to the apparent heterogeneity in the conditions grouped together as CPHP, it is difficult to determine a definitive aetiology for the condition.[6]

Many causative factors for CPHP have been hypothesised in the literature and are commonly characterised as intrinsic or extrinsic. Intrinsic factors are characteristics of an individual that predispose them to injury.[6] Those suggested in the literature include limited first metatarsophalangeal joint (MPJ) range of motion (ROM), limited ankle dorsiflexion ROM, leg length discrepancy, reduced heel pad thickness, increased plantar fascia thickness, excessive foot pronation, reduced calf strength, calcaneal spur, older age and increased body mass index (BMI).[1,7,8] Environmental and circumstantial influences acting upon an individual are known as extrinsic factors, and include prolonged standing, inappropriate shoe fit, previous injury and running surface, speed, frequency and distance per week.[1,6,7] Empirical evidence for most of these factors is limited or absent,[9] meaning that the role (if any) of each of these factors in the development of CPHP is poorly understood.

In an attempt to help address this lack of empirical evidence, a matched case-control study was undertaken to examine the association between CPHP and a number of causative factors suggested in the literature. Factors for inclusion into the study were selected because they each had a small amount of evidence supporting an association with CPHP,[9] which required further investigation. As it was obviously impractical to examine all factors requiring further investigation, the authors attempted to select those factors that are routinely assessed by clinicians in the management of heel pain. It was hypothesised that pronated foot posture, increased BMI, decreased ankle dorsiflexion ROM, increased occupational lower limb stress and decreased calf endurance would all be associated with CPHP.

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