Subtalar Joint Axis Location and Rotational Equilibrium Theory of Foot Function

A new theory of foot function based on the spatial location of the subtalar joint axis in relation to the weightbearing structures of the plantar foot is proposed. The theory relies on the concept of subtalar joint rotational equilibrium to explain how externally generated forces, such as ground reaction force, and internally generated forces, such as ligamentous and tendon tensile forces and joint compression forces, affect the mechanical behavior of the foot and lower extremity. The biomechanical effect of variations among individuals in the spatial location of the subtalar joint axis are explored, along with their clinical consequences, to offer an additional theory of foot function, which may improve on existing podiatric biomechanics theory. (J Am Podiatr Med Assoc 91(9): 465-487, 2001)

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The Subtalar Joint Axis Locator

Journal of the American Podiatric Medical Association ◽

10.7547/0960212 ◽

2006 ◽

Vol 96 (3) ◽

pp. 212-219 ◽

Cited By ~ 4

Author(s):

Simon K. Spooner ◽

Kevin A. Kirby

Keyword(s):

Subtalar Joint ◽

Dynamic Capabilities ◽

Three Dimensional ◽

Spatial Location ◽

Exit Point ◽

Neck Position ◽

Dorsal Aspect ◽

Joint Axis ◽

Preliminary Study ◽

Rotational Motions

A new clinical device, the subtalar joint axis locator, was created to track the three-dimensional location of the subtalar joint axis during weightbearing movements of the foot. The assumption was that if the anterior exit point of the subtalar joint axis is stationary relative to the dorsal aspect of the talar neck, then, by performing radiographs of the feet with the subtalar joint axis locator in place on the foot, the ability of the locator to track rotations and translations of the talar neck and thus the subtalar joint axis in space could be approximated. In this preliminary study of two adults, the subtalar joint axis locator accurately tracked the talar neck position during weightbearing rotational motions of the subtalar joint. The device was also used in a series of subjects to determine its dynamic capabilities. It is possible, then, that the subtalar joint axis locator can reliably track the spatial location of the subtalar joint axis during weightbearing movements of the foot. (J Am Podiatr Med Assoc 96(3): 212–219, 2006)

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Function of the Windlass Mechanism in Excessively Pronated Feet

Journal of the American Podiatric Medical Association ◽

10.7547/87507315-91-5-245 ◽

2001 ◽

Vol 91 (5) ◽

pp. 245-250 ◽

Cited By ~ 19

Author(s):

Anna Aquino ◽

Craig Payne

Keyword(s):

Subtalar Joint ◽

Gait Cycle ◽

Length Ratio ◽

Chi Square ◽

Foot Length ◽

Joint Axis ◽

Visual Evidence ◽

Foot Function ◽

Axis Position ◽

Chi Square Analysis

The foot postures of 39 subjects were evaluated for excessive pronation by means of six static weightbearing and five nonweightbearing measurements, and two types of footprint indexes. Visual evidence of windlass function was recorded by video. Chi-square analysis revealed that excessive pronation does not affect the establishment of the windlass mechanism. The position of the forefoot relative to the rearfoot, subtalar joint axis position, and navicular drift/foot length ratio were significantly associated with dynamic windlass function. These results suggest that selected static measurements may have value in predicting some aspects of dynamic foot function during the propulsive phase of the gait cycle. (J Am Podiatr Med Assoc 91(5): 245-250, 2001)

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Biomechanics of the normal and abnormal foot

Journal of the American Podiatric Medical Association ◽

10.7547/87507315-90-1-30 ◽

2000 ◽

Vol 90 (1) ◽

pp. 30-34 ◽

Cited By ~ 37

Author(s):

KA Kirby

Keyword(s):

Lower Extremity ◽

Subtalar Joint ◽

Physical Activities ◽

The Body ◽

Lower Extremity Function ◽

Joint Function ◽

Extremity Function ◽

Foot Function

The foot is an engineering marvel that allows the body to perform many physical activities over a wide variety of terrain with remarkable efficiency. The functions of the foot and the lower extremity are biomechanically integrated; thus normal lower-extremity function requires normal foot function and vice versa. Because the subtalar joint is the main pedal joint allowing the triplanar translation of motion between the foot and lower extremity, normal subtalar joint function is critical to normal foot and lower-extremity function. This article provides an overview of the interrelationships between foot and lower-extremity function and mechanically based pathology of the foot and lower extremity, with an emphasis on the subtalar joint.

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The Subtalar Joint Axis Palpation Technique

Journal of the American Podiatric Medical Association ◽

10.7547/0003-0538-104.4.365 ◽

2014 ◽

Vol 104 (4) ◽

pp. 365-374 ◽

Cited By ~ 6

Author(s):

Ken K. Van Alsenoy ◽

Kristiaan D'Août ◽

Evie E. Vereecke ◽

Joris De Schepper ◽

Derek Santos

Keyword(s):

Subtalar Joint ◽

Positive Influence ◽

Helical Axis ◽

Clinical Tool ◽

Plantar Surface ◽

Joint Axis ◽

Significant Difference ◽

Standard Tool ◽

Rotational Equilibrium ◽

Cadaver Specimen

Background Clinically locating the point of no rotation to determine the subtalar joint axis location by applying pressure on the plantar surface of the foot was described by Kirby in 1987 but was never validated. We sought to extend a previously validated mechanical model to cadaver feet and to examine the intratester and intertester reliability. Methods Four testers with different levels of experience determined the subtalar joint axis location and moved the subtalar joint through its range of motion, capturing the movement using kinematic analysis. The comparison of the spatial subtalar joint axis location as determined by palpation between and within testers determined the intertester and intratester reliability. The helical axis method was performed to validate the model. Results The intrarater reliability varied from a high of α = 0.96 to a low of α = 0.26 for the slope and was, in general, high (α = 0.78–0.95) for the intersection. The interrater reliability scored moderate to high, depending on the specific cadaver specimen. Concerning the exact location of the subtalar joint axis, no significant difference was found between the results determined by different testers and the helical axis method. Conclusions The palpation technique as part of the subtalar joint axis location and rotational equilibrium theory proposed by Kirby is a reliable and valid clinical tool. Experience in performing the palpation technique has a positive influence on the accuracy of the results. In the context of evidence-based practice, this technique could be a standard tool in the examination of patients with lower-limb–related pathologic disorders.

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Rotational equilibrium across the subtalar joint axis

Journal of the American Podiatric Medical Association ◽

10.7547/87507315-79-1-1 ◽

1989 ◽

Vol 79 (1) ◽

pp. 1-14 ◽

Cited By ~ 28

Author(s):

KA Kirby

Keyword(s):

Subtalar Joint ◽

Foot Orthoses ◽

Bipedal Stance ◽

Joint Axis ◽

Sinus Tarsi ◽

Sinus Tarsi Syndrome ◽

Rotational Equilibrium ◽

Mechanical Basis

A review of the rotational forces, or moments, acting across the subtalar joint axis during relaxed bipedal stance is presented. The concept of rotational equilibrium about the subtalar joint axis is used to explain some of the biomechanical differences between feet that stand in the neutral and maximally pronated subtalar joint positions. In addition, the mechanical basis of treatment of sinus tarsi syndrome with foot orthoses using the concepts of subtalar joint axis moments rotational equilibrium of the subtalar joint is presented.

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Position of the Subtalar Joint Axis and Resistance of the Rearfoot to Supination

Journal of the American Podiatric Medical Association ◽

10.7547/87507315-93-2-131 ◽

2003 ◽

Vol 93 (2) ◽

pp. 131-135 ◽

Cited By ~ 15

Author(s):

Craig Payne ◽

Shannon Munteanu ◽

Kathryn Miller

Keyword(s):

Subtalar Joint ◽

Sagittal Plane ◽

Metatarsal Head ◽

Foot Orthoses ◽

Joint Axis ◽

Foot Function ◽

Two Parameters ◽

The Relationship ◽

Clinical Determination

Determination of the position of the subtalar joint axis is being more widely used clinically to facilitate the prescription of foot orthoses and the understanding of foot function, but clinical determination of the axis has not been widely investigated. The aim of this study was to determine the relationship between clinical determination of the subtalar joint axis and the amount of force needed to supinate the foot. The transverse plane position of the subtalar joint axis was determined in 47 subjects. The sagittal plane orientation of the subtalar joint axis was determined using the relative amounts of forefoot adduction and abduction obtained when the rearfoot was supinated and pronated. The amount of force needed to supinate the foot was measured using a device designed to measure resistance to supination. The only two parameters that were correlated to supination resistance of the rearfoot were body weight (r = 0.52) and the perpendicular distance from the fifth metatarsal head to the subtalar joint axis (r = 0.59). The model on which determination of the subtalar joint axis is based may not be valid, but it might help determine how much force is needed to supinate a foot using foot orthoses. (J Am Podiatr Med Assoc 93(2): 131-135, 2003)

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Finite Element Model Proposed for Determine the Rotational Equilibrium Around of the Subtalar Joint Axis (SJA)

10.1007/978-3-030-91234-5_65 ◽

2021 ◽

pp. 650-657

Author(s):

Rubén Lostado Lorza ◽

Fátima Somovilla Gomez ◽

Saúl Íñiguez Macedo ◽

Marina Corral Bobadilla ◽

María Ángeles Martínez Calvo ◽

...

Keyword(s):

Finite Element ◽

Finite Element Model ◽

Subtalar Joint ◽

Element Model ◽

Joint Axis ◽

Rotational Equilibrium

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Center of pressure and its theoretical relationship to foot pathology

Journal of the American Podiatric Medical Association ◽

10.7547/87507315-89-6-278 ◽

1999 ◽

Vol 89 (6) ◽

pp. 278-291 ◽

Cited By ~ 64

Author(s):

EA Fuller

Keyword(s):

Subtalar Joint ◽

Center Of Pressure ◽

Theoretical Explanation ◽

Theoretical Relationship ◽

Model Based ◽

Joint Axis ◽

Foot Function

The measurement of center of pressure has been widely used in the evaluation of foot function. This article will describe center of pressure and indicate how it can be used to calculate moments about the joint axes of the foot. Various uses of center of pressure described in the literature will be examined. A model based on the use of the location of center of pressure relative to the location of the subtalar joint axis will be proposed as a theoretical explanation of selected foot pathologies and their treatment.

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Lower Extremity Biomechanics Predicts Major League Baseball Player Performance

Orthopaedic Journal of Sports Medicine ◽

10.1177/23259671211015237 ◽

2021 ◽

Vol 9 (7) ◽

pp. 232596712110152

Author(s):

Lucas G. Teske ◽

Edward C. Beck ◽

Garrett S. Bullock ◽

Kristen F. Nicholson ◽

Brian R. Waterman

Keyword(s):

Lower Extremity ◽

Major League Baseball ◽

Reaction Force ◽

Regression Trees ◽

Minimal Detectable Change ◽

Vertical Force ◽

Baseball Players ◽

Major League ◽

Lower Extremity Biomechanics ◽

Statistical Metrics

Background: Although lower extremity biomechanics has been correlated with traditional metrics among baseball players, its association with advanced statistical metrics has not been evaluated. Purpose: To establish normative biomechanical parameters during the countermovement jump (CMJ) among Major League Baseball (MLB) players and evaluate the relationship between CMJ-developed algorithms and advanced statistical metrics. Study Design: Cohort study; Level of evidence, 3. Methods: MLB players in 2 professional organizations performed the CMJ at the beginning of each baseball season from 2013 to 2017. We collected ground-reaction force data including the eccentric rate of force development (“load”), concentric vertical force (“explode”), and concentric vertical impulse (“drive”) as well as the Sparta Score. The advanced statistical metrics from each baseball season (eg, fielding independent pitching [FIP], weighted stolen base runs [wSB], and weighted on-base average) were also gathered for the study participants. The minimal detectable change (MDC) was calculated for each CMJ variable to establish normative parameters. Pearson coefficient analysis and regression trees were used to evaluate associations between CMJ data and advanced statistical metrics for the players. Results: A total of 151 pitchers and 138 batters were included in the final analysis. The MDC for “load,” “explode,” “drive,” and the Sparta Score was 10.3, 8.1, 8.7, and 4.6, respectively, and all demonstrated good reliability (intraclass correlation coefficient > 0.75). There was a weak but statistically significant correlation between the Sparta Score and wSB ( r = 0.23; P = .007); however, there were no significant correlations with any other advanced metrics. Regression trees demonstrated superior FIP with higher Sparta Scores in older pitchers compared with younger pitchers. Conclusion: There was a positive but weak correlation between the Sparta Score and base-stealing performance among professional baseball players. Additionally, older pitchers with a higher Sparta Score had statistically superior FIP compared with younger pitchers with a similar Sparta Score after adjusting for age.

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