Foot morphology and its relationship to arch height index in asymptomatic adults versus adults presenting with foot pain (nontraumatic)

Alok Chandra Agrawal; Abu Ubaida Siddiqui; Harshal S Sakale; Meryl Rachel John

doi:10.4103/NJCA.NJCA_218_22

ORIGINAL ARTICLE

Year : 2023 | Volume : 12 | Issue : 1 | Page : 15-19

Foot morphology and its relationship to arch height index in asymptomatic adults versus adults presenting with foot pain (nontraumatic)

Alok Chandra Agrawal¹, Abu Ubaida Siddiqui², Harshal S Sakale³, Meryl Rachel John⁴
¹ Professor, Department of Orthopaedics, All India Institute of Medical Sciences, Raipur, Chhattisgarh, India
² Additional Professor, Department of Anatomy, All India Institute of Medical Sciences, Raipur, Chhattisgarh, India
³ Associate Professor, Department of Orthopaedics, All India Institute of Medical Sciences, Raipur, Chhattisgarh, India
⁴ Senior Resident, Department of Anatomy, All India Institute of Medical Sciences, Raipur, Chhattisgarh, India

Date of Submission	02-Nov-2022
Date of Decision	14-Dec-2022
Date of Acceptance	29-Dec-2022
Date of Web Publication	21-Feb-2023

Correspondence Address:
Abu Ubaida Siddiqui
Department of Anatomy, All India Institute of Medical Sciences, Raipur - 492 099, Chhattisgarh
India

Source of Support: None, Conflict of Interest: None

DOI: 10.4103/NJCA.NJCA_218_22

Abstract

Background: The uniqueness of the human foot, in performing various functions, is intricately associated with different morphological parameters, and arch height index (AHI) is an important parameter for the same. The measurement of AHI has putative clinical implications in correcting the underlying causative factors, which contribute to foot pain. This study was an attempt to investigate these parameters as a correlation among asymptomatic versus patients complaining of foot pain (due to nontraumatic causes). Methodology: One hundred asymptomatic and 50 symptomatic adults were engaged in the study after taking prior consent. Various measurements (such as foot length, truncated foot length, foot breadth, arch height – [AH], and AHI) were taken in a standing position. In this study values of foot length, truncated foot length, foot breadth, AH and AHI were compared amongst the two groups . Comparison was done with earlier studies. Results: The difference in AH and AHI (P < 0.05) among the asymptomatic versus the foot pain patients, was significant. There was a considerable difference in body weight and Body Mass Index (BMI) affecting AH and AHI. AHI in the case of the symptomatic foot pain adults was 0.18 in both feet, with a standard deviation (SD) of 0.07. Conclusion: The AHI has been considered an essential parameter in defining and identifying the potential structural factors that predispose an individual to injuries of the foot. Our results indicate that the mean AHI in the case of foot pain adults (nontraumatic) was 0.18 in both feet, with an SD of 0.07. This is lower as compared to other studies. This can be attributed to the fact that earlier studies have been done on asymptomatic patients only. The present study was done to correlate between normal asymptomatic versus foot pain patients. There was a significant difference in the AH and AHI between our two study groups.

Keywords: Arch height index, arch height, foot pain, medial longitudinal arch, morphology, nontraumatic

How to cite this article:
Agrawal AC, Siddiqui AU, Sakale HS, John MR. Foot morphology and its relationship to arch height index in asymptomatic adults versus adults presenting with foot pain (nontraumatic). Natl J Clin Anat 2023;12:15-9

How to cite this URL:
Agrawal AC, Siddiqui AU, Sakale HS, John MR. Foot morphology and its relationship to arch height index in asymptomatic adults versus adults presenting with foot pain (nontraumatic). Natl J Clin Anat [serial online] 2023 [cited 2023 Mar 20];12:15-9. Available from: http://www.njca.info/text.asp?2023/12/1/15/370135

Introduction

The human foot, due to its unique anatomical arrangement, has always been a subject of intrigue among scientists globally. The functionality of the foot extensively depends on various morphological parameters. Deviations from the normal parameters influence and alter the biomechanical properties of the foot. Thus, a proper understanding and analysis of these parameters help in understanding the basis of deformities of the foot as well as foot dysfunction disorders.^[1]

The human foot bears the body weight and also performs like a shock absorber. The variety of motion changes is very effectively managed by the foot. This becomes possible due to the perfect alignment of various anatomical components, including the soft tissue as well as the bony characters. The morphology of the foot is intricately associated with the functions of the foot, and thus, various parameters help us in a better understanding of the structure-function relationship. Multiple parameters influence the basic functioning of the foot. These parameters of the foot have been extensively investigated worldwide, across different study groups. These parameters include foot length, truncated foot length, foot breadth, arch height (AH), AH index (AHI), and many more. These parameters have provided useful information in different geographical populations and subjects involving a variety of races globally. The parameters have been explored under differing pretexts and contexts. The AHI has always been sustained as a trustworthy and understandable parameter among anatomists, morphologists, physiotherapists, orthopedists, and podiatrists.^[1],[2]

Zhao et al. conducted a study on the morphology of 180 adult feet and its correlation with age, gender, and body mass index.^[1] Zhao et al., in 2020, did a cross-sectional study on 173 participants, examining AH and arch stiffness under the influence of factors that included age, gender, and BMI.^[2] Saghazadeh et al. concluded that the value of AHI is dependent on balance and postural sways and thus plays a vital role in defining balance control in older women.^[3] Various authors have indicated that the AHI is a useful measure that can be elicited from the footprints of subjects, and this index can be a predictor of AH.^[4],[5] The AHI is a very reliable parameter in identifying the structural factors that may have the potential to predispose individuals to lower limb injuries.^[6] The curvilinear relationship between AH and incremental loading, as described by Bjelopetrovich and Barrios assessed the difference in AH among sitting as well as standing postures in 25 individuals.^[7] In 2017, Zifchock et al. calculated AHI in 1124 military cadets and concluded that cavus feet were very stiff, whereas the planus feet were flexible.^[8] Other researchers have also extensively studied the AHI concerning the classification of foot types, gender, age, BMI, and the risk of exercise-related injury.^{[9],[10],[11],[12],[13],[14],[15],[16]}

Taking into consideration the relevance of different morphological parameters of the foot, the present project was undertaken to look into the differences in morphological parameters of the foot among two different study groups. The control group consisted of asymptomatic young adults. The second group comprised patients complaining of foot pain (nontraumatic). Particular emphasis was given to the AHI, considering its putative clinical implications in the functions of the foot.

Materials and Methods

Ethical Committee approval was taken for the study vide letter number AIIMSRPR/IEC/2017/079.

The present cross-sectional study included 100 asymptomatic adults and 50 adults with foot pain (nontraumatic). These 50 symptomatic adults were selected from the outpatient department patients of AIIMS, Raipur. Participants were categorized by gender, age, height, and BMI to compare the differences in the morphology of the foot. Measurements for both feet were taken in a standing position. The measurements were taken as footprints on graph paper, a meter ruler, and measuring tape. The parameters included were foot length, truncated foot length, foot breadth, AH, and AHI.

Inclusion criteria

Free from gross lower extremity abnormalities/injury
No history of any condition that prevented them from prolonged standing or shifting body weight on the foot
Normal gait
No apparent pain/discomfort in walking
No signs of trauma/surgery
Age group 18–60 years.

Exclusion criteria

Subjects under 18 years/over 60 years
Patients with foot anomalies, inflammation, any sign of trauma, obvious deformities, and surgical history
Antalgic gait/asymmetric gait
Open wounds/skin disease on the plantar surface of the foot
Any fractures/burns.

Before initiating the study, consent was obtained from all subjects in English and their native language. All the participants were barefoot at the time of recording the measurements. All the measurements done for the study were undertaken with the participants standing erect against the wall in the proper anatomical position. The methodology undertaken is described as follows:

Foot length was measured with a transparent meter rule with the ankle perpendicular to the foot. It was estimated by pinning the posterior prominence of the heel to the tip of the longest toe on the plantar aspect of the foot. The first toe is the longest in some people, whereas, in others, the second toe is the longest. The person was told to keep the foot on plain sheet paper; a marker was used to mark the length of the foot, and the points were measured using a measuring tape.^[1]
Truncated foot length – This reading was taken following the method adopted by Williams and McClay. They have defined the truncated foot length to be the distance from the most posterior portion of the calcaneus to the center of the first metatarsophalangeal joint.^[15] Some authors have defined it as the distance from the most posterior point on the calcaneus to the most distal end on the first metatarsal head.^[6],[17]
Foot breadth was also measured as the distance between the medial most points situated on the head of the first metatarsal to the most laterally placed end on the head of the fifth metatarsal. The person kept the foot on a plain sheet of paper/graph paper. A marker marks the breadth of the foot; the points were measured by measuring tape.^[1]
Arch height (dorsum height) – was measured as the height of the dorsum of the foot (taken at 50% of foot length, i.e., the height of the arch at half resting foot length).^{[6],[8],[14],[15]}
Arch height index – AHI is utilized to measure the medial longitudinal arch, and it can be utilized to categorize the foot into various types, such as high arched, regular, and low arched. We took measurements similar to the method adopted by Williams and McClay,^[15] who compared various ratios and measurements of the foot and concluded that the height of the dorsum of the foot at 50% of foot length divided by truncated foot length was a very reliable and valid measure to determine AHI. A digital caliper and a graph sheet were utilized for taking the measurement. After measuring foot length (vide supra), the midway point of the foot was defined (50% of foot length), and from this point, a vertical measurement was taken up to the top of the foot (AH-vide supra). Then divide the AH value by the length of the foot from your heel to the ball of the first toe. The formula used for AHI was as follows [Figure 1].^[15] Shows various parameters utilized for calculating Arch Height Index (AHI).

Figure 1: AHI = height of the dorsum of the foot at 50% of foot length ÷ Truncated foot length

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Results

The readings were tabulated and presented in the following tables. [Table 1] shows the gender distribution in the study groups. [Table 2] shows the various parameters which were undertaken in the present study. Using the independent t-test, it was confirmed that the P value was significant between asymptomatic and non -traumatic foot pain groups; for weight, BMI, AH, and AHI. Statistically significant reduction in the value of AH and AHI between the 2 groups was observed on the right foot. Further comparisons with earlier studies are tabulated in [Table 3].

Table 1: Distribution of gender in the study population

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Table 2: Comparison of parameters between the two groups

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Table 3: Comparison of data in foot pain adults of present study with previous studies data taken in asymptomatic adults

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[Table 2] indicates that there is a statistically significant difference in the P value as far as the AH and AHI is concerned. A significant difference between the right and the left foot is also observed.

Discussion

The present study intended to elaborate upon the foot morphology among the targeted population and their affection for foot pain. Furthermore intended was the reliability and plausibility of various foot measurements, which can be utilized to analyze and validate different aspects concerning the foot, which also included the medial longitudinal arch with particular reference to AHI. The importance of the study lies in the fact that there is minimal data on the foot morphology of the Indian population concerning foot pain, i.e., one of the sinister complaints that bring the patient to a doctor. Unexplained foot pain (nontraumatic) is a common complaint in apparently normal adults. This can be ascribed to the weakness/loss of the arches of the foot (especially the medial longitudinal arch). Bodyweight is also considered a culprit in the compromise of foot functions due to its long-term implications. BMI shall always remain an essential indicator of foot pathology apart from the various anatomical and structural features of the respective feet.

A significant difference (P < 0.05) was reported among asymptomatic as well as foot pain patients, as far as the AH and AHI are concerned [Table 2]. Looking into the findings of earlier workers, it is self-evident that various methodologies have been adopted to investigate these morphological parameters. The results vary across different populations, which can be attributed to the variations in body weight, BMI, and varying morphological parameters (such as medial and lateral longitudinal arches). Butler et al. performed the study on 100 recreational runners and concluded that the mean ± standard deviation (SD) AHI in their subjects was 0.34 ± 0.030.^[6] In the study by Williams and McClay on 52 subjects, the AHI was reported to be 0.31.^[15] Zhao et al. reported the values of AHI as 0.35 and 0.34 in their studies.^[1],[2] The findings of other researchers are shown in [Table 3].

Such patients can also develop sesamoiditis, corns, keratosis, plantar heel pain, ankle sprains, or stress fractures. Also reported in flatfoot patients is the increased incidence of osteoarthritis affecting the first metatarsophalangeal joint, knee pain, plantar fasciitis, and patellar tendinitis.^[2]

The dimensions of the foot vary amongst different populations and are greatly influenced by genetic as well as environmental/social factors. As described anatomically, our foot has two longitudinal arches (medial and lateral). During gait, the foot serves as a shock absorber which is flexible by nature and also can deform, in response to walking on uneven surfaces; before undergoing a series of biomechanical changes. This allows the foot to act as a rigid lever to exert force.^[18] Understanding the complex anatomy of the foot is one of the most essential parts of practice in orthopedics. The present study was undertaken on the patients presenting with non-traumatic foot pain. This study aimed at analyzing various parameters of the arch, especially the AHI. These patients had foot pain but had no associated condition. They were also free from any gross foot abnormalities or injuries.

The human foot, a gifted marvel, is uniquely designed with two longitudinal arches and two transverse arches.^[19] These arches assist us in standing, walking, and running and aid the foot in adapting to different ground planes, absorbing shock, meticulous transfer of weight, and accurate locomotion. The morphological parameters of these arches strongly influence the biomechanics of the foot as well as the lower limb. Various researchers have proved that the height of the medial longitudinal arch can be the predisposing factor leading to lower limb injuries. Individuals suffering from both pes cavus and pes planus feet are at increased risk for the development of various stress fractures in the foot and lower limb.^[1],[2],[3] Abnormal anatomy of the medial longitudinal arch of the foot is considered a relevant predisposing factor to the injury.^[15] Moreover, increased joint laxity is also a significant concern that may enhance foot arch flexibility, which eventually culminates in malalignment and pain.^[20]

The AHI is deemed helpful in the identification of potential structural factors which may predispose many individuals to injuries to the lower limb.^[6] The AHI also plays a vital role in defining balance control and postural sway in a person.^[3] AHI has repeatedly been proven as a very valid and reliable tool that can be undertaken quickly by a trained clinician.^[13] The AH and AHI have the potential to be utilized to deduce the causative factors, further, so that proper corrective measures can be applied by orthopedics, podiatrists, and other interventionists. Further extrapolation is still needed across different geographical populations to know about the association in varying races worldwide and add to the knowledge of the variability of the AHI across the normal and pathological foot.

Conclusion

Results from the present study indicate that the mean AHI in the case of foot pain adults (nontraumatic) was 0.18 in both feet, with an SD of 0.07. This is lower as compared to other studies. This can be attributed to the fact that earlier studies have been done on asymptomatic subjects only. The present study was done to correlate between normal asymptomatic versus foot pain patients. There was a significant difference in the AH and AHI between our two study groups [Table 2]. This implies that a reduction in the height of arches can lead to difficulty in wearing footwear, the occurrence of hammertoes, and metatarsalgia.

The present project was undertaken to understand the morphological aspects of the foot with the sinister complaint of foot pain in this part of the world. There are very limited data on the Indian population; other authors can utilize the present study for future prospective analyses around the world.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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