Walking ability and foot pressure pattern associated with spinal kyphosis

Background: Although kyphosis and its mobility are reported to be associated with walking ability in elderly people, the causal relationship between them has not been clarified. Purpose:Toclarify the foot pressure pattern in individuals with kyphosis and examine the relationship between spinal kyphosis, mobility, foot pressure pattern, and walking ability. Methods: In 61participants, total inclination and thoracic, lumbar, and sacral anglesweremeasured by the SpinalMouse (IdiagAG,Switzerland). Forty-one of the 61participantswith total inclination >6 degrees and/or lumbar angle < 16 degrees were classified as the kyphosis group (6 men, 35 women; mean age, 78.5 years). The other 20 participants were classified as the control group (3 men, 17 women; 75.5 years). Spinal mobility of the total, thoracic, lumbar, and sacral spine was measured. Walking speed and step length at a comfortable walking speedweremeasured on a flat and straight 10-m course. Simultaneously, the foot pressure pattern was measured by the insole-type foot pressure measurement system (F-Scan II, Nitta, Japan). The anteroposterior length of the center of pressure (COP) path, expressed as the percentage of the foot length (%Long), the transverse width of the COP path, expressed as the percentage of maximum foot width (%Trans), and the partial foot pressure in the heel, central, metatarsal, hallux, and lateral toe area, expressed as the percentage of body weight (%PFP), were calculated. Results: Walking speed (0.8± 0.3 vs. 1.1± 0.3m/s, p= 0.031) and step length (0.4± 0.1 vs. 0.5± 0.1m, p= 0.042) in the kyphosis groupwere significantly lower than those in the control group. Total inclination in the kyphosis group was significantly higher than that in the control group (8.3± 8.2 vs. 1.0± 3.2 degrees, p= 0.007). Lumbar angle (−1.4± 17.2 vs. 24.9± 4.3 degrees, p= 0.008) and sacral inclination (−3.1± 9.3 vs. 9.9± 4.5 degrees, p= 0.008) in the kyphosis group were significantly lower than those in the control group. In the kyphosis group, mobility of the total, lumbar, and sacral spine was significantly lower than that of the control group. The %Long, %Trans, and %PFP of the hallux (4.4± 3.6 vs. 15.1± 6.4%, p= 0.034) and lateral toes (4.2± 3.2 vs. 9.7± 5.4%, p= 0.036) in the kyphosis groupwere significantly lower than those in the control group. A significant correlation was found between spinal inclination and %PFP of the hallux (r=−0.344) and lateral toes (r=−0.310). The %PFP of the hallux (r=0.560) and lateral toes (r= 0.437) also correlated with total spinal mobility. Conclusion(s): In individuals with spinal kyphosis, a decreased walking ability was evident, and severe kyphosis and low mobility of the spine were associated with low toe pressure. Thus, low toe pressure might induce insufficient driving forces, causing decreased walking ability. Implications:We should pay careful attention to the presence of low toe pressure in individuals with spinal kyphosis.