The Association of Pes Planus and Calf Muscle Tightness Among School-Age Children

Abstract

Background: Pes planus is a common pediatric foot posture variant characterized by medial longitudinal arch collapse during weight bearing and has been linked to altered lower-limb biomechanics, including restricted ankle dorsiflexion leading to compensatory pronation. Objective: To determine the association of pes planus and calf muscle tightness (gastrocnemius and soleus) among school-age children. Methods: A cross-sectional observational study was conducted over six months at PSRD Hospital Lahore and PSRD High School Lahore using convenience sampling. Children aged 6–12 years were classified as pes planus or normal foot posture using Jack’s test. Ankle dorsiflexion was measured bilaterally with a goniometer in knee extension (gastrocnemius) and knee flexion (soleus) and categorized into severity bands. Associations were tested using Pearson’s chi-square with effect sizes (Cramér’s V). Results: Among 142 children (mean age 9.16 ± 2.04 years; 54.2% male), 86 (60.6%) had pes planus. Pes planus was strongly associated with gastrocnemius tightness bilaterally (χ²=118.52, df=2, p<0.001; Cramér’s V=0.65), with severe tightness present in ~65% of the pes planus group versus ~11% without pes planus. Soleus tightness was also associated with pes planus (right: χ²=62.01, df=2, p<0.001; V=0.47; left: χ²=44.31, df=1, p<0.001; V=0.40). Conclusion: School-age children with pes planus demonstrate significantly higher prevalence of calf muscle tightness, particularly gastrocnemius restriction, supporting routine dorsiflexion assessment in pediatric flatfoot evaluation.