Relationships between clinical measures of static foot posture and plantar pressure during static standing and walking
Introduction
Medial longitudinal arch (MLA) posture of the foot has been related to lower extremity injury, although the nature of this relationship remains equivocal. High arches have been associated with more laterally located bony injuries of the foot (Williams et al., 2001), foot pain (Burns et al., 2005), ankle injuries, knee pain (Dahle et al., 1991), and lower extremity stress fractures (Kaufman et al., 1999, Williams et al., 2001). Low arches have been associated with soft tissue injuries such as patellar tendinitis, plantar fasciitis (Williams et al., 2001), and knee pain (Dahle et al., 1991, Williams et al., 2001). However, other studies have failed to demonstrate significant relationships between foot posture and lower extremity injury (Baumhauer et al., 1995, Michelson et al., 2002) or have suggested that some foot postures may be protective against some types of injuries (Cowan et al., 1993, Wen et al., 1998). Nevertheless, clinicians commonly use static measurements of MLA posture to infer dynamic foot function in order to assess the potential for lower extremity dysfunction that may increase injury risk.
Plantar pressure distribution has been used to characterize dynamic foot function (Cavanagh et al., 1997, Morag and Cavanagh, 1999, Yalçin et al., 2010) and has been related to several foot-specific pathologies (e.g., Imhauser et al., 2006, Masson et al., 1989, Minns and Craxford, 1984). For example, greater regional plantar pressure values have been associated with diabetic ulceration (Masson et al., 1989, Veves et al., 1992), forefoot rheumatoid arthritis, hallux valgus deformity (Minns and Craxford, 1984), medial midfoot osteoarthritis (Menz et al., 2010), and posterior tibialis tendon dysfunction leading to flatfoot deformity (Imhauser et al., 2006), although cause–effect relationships are not always clear.
Although MLA posture and plantar pressure measures each have been associated with lower extremity and foot-specific disorders, the extent to which they are interrelated is not completely understood. A few studies have examined the relationships between plantar pressure and radiographic measures of MLA-related foot structure (e.g., metatarsal and calcaneal inclination angles, navicular height, foot contact area; Cavanagh et al., 1997, Morag and Cavanagh, 1999), while other studies have examined the relationships between plantar pressure and manually-obtained measures of MLA-related foot structure (e.g., arch angle, arch height, arch height index, navicular height, rearfoot angle; Chuckpaiwong et al., 2008, Queen et al., 2009, Teyhen et al., 2009). However, there is limited information about the relationships between plantar pressure under the medial column of the foot and the common clinical measures of MLA posture arch index (AI), navicular drop (NDp), and navicular drift (NDt). Since some clinicians use these measures of MLA posture to inform clinical decisions, a more thorough understanding of their relationships to measures of dynamic foot function, such as plantar pressure, is warranted.
Few studies have examined the relationships between common clinical measures of MLA posture and plantar pressure. Teyhen et al. (2009) investigated the relationship between peak regional plantar pressure values and AI during walking and found that greater arch height was associated with greater lateral forefoot pressure. Albensi et al. (1999) investigated the relationship between peak rearfoot force (calculated from plantar pressure) and NDp during walking and found that lower arch height was associated with higher rearfoot force. In contrast, Burns et al. (2005) reported greater rearfoot pressure in pes cavus (high arch) feet compared to normal feet, but arch height was characterized using the Foot Posture Index and not NDp. We found no studies that examined the relationships between regional plantar pressure values and NDt during walking. Because there is limited information about the relationships between peak plantar pressure values under the medial column of the foot and AI, NDp and NDt, and because a greater understanding of these relationships may provide additional insight about the interdependence of MLA posture and dynamic foot function which could lead to more informed clinical decisions, the purpose of our study was to explore these relationships during static standing and walking in healthy subjects with asymptomatic feet.
Section snippets
Design
A single group exploratory design using correlation and multiple linear regression methods was used to determine the relationships between clinical measures of static MLA posture and plantar pressure during static standing and walking conditions.
Subjects
Ninety-two participants (42 men, 50 women; 184 feet) between the ages of 18–35 years were recruited for the study. The mean (and standard deviation) age and mass were 25.8 (6.7) years and 72.9 (16.7) kg, respectively. Participants were selected from a
Results
The reliability of the static MLA postural measurements ranged from moderate to excellent. Intra-class correlation coefficient values for the three static MLA measurements were 0.80 (95% Confidence Interval, CI: 0.67 to 0.89), 0.95 (95% CI: 0.91 to 0.97) and 0.91 (95% CI: 0.85 to 0.95), for the AI, NDp and NDt variables, respectively. Descriptive statistics for the three static MLA postural measurements were consistent with values reported in the literature (Cote et al., 2005, Vinicombe et al.,
Discussion
Measurements of MLA posture, such as AI, NDp and NDt, have been used to infer dynamic foot function and guide clinical intervention, but their relationships with peak regional plantar pressure values are not well understood. The purpose of our study was to explore the relationships between AI, NDp and NDt, and peak plantar pressure values under the medial column of the foot during static standing and walking in healthy subjects with asymptomatic feet.
The significant correlation results suggest
Conclusions
Arch index, navicular drop, and navicular drift are significantly related to peak plantar pressure magnitudes under the medial column of the foot during both static standing and walking in healthy participants with asymptomatic feet. As arch height decreases, hallux and medial midfoot plantar pressures increase, while medial forefoot pressures decrease. These relationships may suggest important patterns of plantar pressure loading in feet with different MLA postures that could be clinically
Acknowledgements
We would like to thank The Alaska Club Midtown located in Anchorage, Alaska for allowing us to use their facility for data collection. Additionally, we would like to thank Tekscan for providing a reduced price on the insole sensors used in the study. Finally, thank you to Dr. Ronald Thane Morgan and the Amarillo, Texas Sports Medicine and Orthopedic Center for permitting us to use their Tekscan system.
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