Linear and Angular Measurements of the Foot of Modern Humans: A Test of Morton'S Foot Types

Abstract

In his classic research, Morton established two functionally different configurations of the bipedal and non-bipedal primate foot: one optimized for stability, with a stiff longitudinal arch and adducted first metatarsal, and the other for compliance. Modern human feet were seen as conforming to the bipedal norm and variation from it as pathology, even though clinical evidence has been clear that variation from the norm of a stiff longitudinal arch or adducted first metatarsal exists. This study aims to document the variation in linear and angular measurements of the foot, using weight-bearing radiographs of 50 randomly selected people (25 men) from an urban US Level 1 trauma center. The radiographs were obtained to "rule-out" a foot fracture after trauma or as comparison films for a contralateral foot injury. Measurements were made using Osirix and correlations among the angular and length measurements were determined using Stata with P < 0.05 and Bonferroni correction for multiple comparisons. We found that foot length was not correlated with angular measurements, except for the angle between the first and fifth metatarsal. People with lower medial longitudinal arches also had more abducted first metatarsals and more vertical posterior facets, in accordance with Morton's foot types. Whether or not this variation in modern humans is linked to functionally important consequences remains to be determined in future research. With the new evidence of a more variable foot structure in fossil hominins, understanding the relationship between foot morphology and function becomes more urgent. Anat Rec, 296:1526Rec, 296: -1533Rec, 296: , 2013. V C 2013 Wiley Periodicals, Inc.Key words: Morton's foot types; arch; angles Conventional wisdom has dictated for almost a century that to be effective, the bipedal foot of a hominin is required to have both a medial longitudinal arch and an adducted (or in-line) first metatarsal (Morton, 2007; Elftman and Manter, 2009). This belief originated in the presence of clinical experience which indicated that many modern human feet are flat (planus) and/or have first metatarsals that substantially diverge from the longitudinal axis of the foot (Morton, 1924a,b) and that these conditions are associated with pain and dysfunction. With this paradigm in place, the extremes of variability in foot morphology of humans have been generally understood as representative of inherent pathology (Kanatli et al., 2012; Pique-Vidal, 1924d) and, therefore, not of interest in understanding the evolution and function of foot

How the three arches of the foot intercorrelate

“…This finding is in agreement with Lautzenheiser and Kramer [13] who reported a good correlation between medial and lateral arches (r = 0.79). Additionally, the CIA has the highest correlation coefficient with C1MA (r = -0.90) and C5MA (r = -0.84) in our study, which indicates its relative importance to the aches.…”

“…Additionally, the CIA has the highest correlation coefficient with C1MA (r = -0.90) and C5MA (r = -0.84) in our study, which indicates its relative importance to the aches. This finding is also supported by the findings of Lautzenheiser and Kramer [13]. The authors reported an excellent correlation between this angle and medial arch (r = -0.81) as well as the lateral arch (r = -0.94) [13].…”

“…This finding is also supported by the findings of Lautzenheiser and Kramer [13]. The authors reported an excellent correlation between this angle and medial arch (r = -0.81) as well as the lateral arch (r = -0.94) [13]. This excellent correlation could be attributed to the fact that calcaneus is common to both arches.…”

The effect of posture on the osseous relations in the foot

“…The mean of the foot angles in the present study were between the values reported in previous studies with radiographs [8,[31][32][33][34][35][36] and skin markers during midstance of gait [37]. The variation across subjects (indicated by the standard deviation in Table 2) was with 14.38 slightly higher than the approximately 108 reported in the literature [8,[31][32][33]35,37,38].…”

“…The variation across subjects (indicated by the standard deviation in Table 2) was with 14.38 slightly higher than the approximately 108 reported in the literature [8,[31][32][33]35,37,38]. The importance of the posture on foot angles can be indicated by the effect of the postures in relation to the variation of the foot angles across subjects (between subject standard deviation).…”