Military Service Can Significantly Aggravate Pes Planus Symptoms
Yes, military service substantially worsens symptoms of pes planus through the high-intensity, repetitive weight-bearing activities inherent to military training, with flatfoot deformity identified as a statistically significant risk factor for developing foot and ankle disorders during service.
Evidence from Military Populations
The relationship between pes planus and symptom aggravation in military settings is well-documented through multiple military cohort studies:
High Injury Rates in Military Training
Military basic training involves intensive weight-bearing activities (running, marching, load-bearing) that place extraordinary stress on the lower extremities. 60-80% of military training injuries are overuse injuries, with 80-90% occurring in the lower extremities 1. Common overuse injuries include plantar fasciitis, Achilles tendinitis, and patellar-femoral syndrome—all conditions that pes planus predisposes individuals to develop.
Flatfoot as a Documented Risk Factor
A comprehensive study of 4,029 Finnish male conscripts found that flatfoot deformity was statistically significantly related to the incidence of foot and ankle disorders during military service 2. Notably, the majority of foot and ankle disorder visits occurred during the first few months of military service, when the transition to intensive physical training is most abrupt.
Specific Injury Correlation
Research on West Point cadets demonstrated statistically significant relationships between the degree of pes planus and total number of injuries sustained (p = 0.007), including specific correlations with midfoot injuries and knee injuries 3. This controlled population study used standardized footprint analysis and followed cadets for 46 months, providing robust evidence of the injury burden.
Mechanism of Symptom Aggravation
The aggravation occurs through several pathways:
- Training intensity: Military training involves cumulative injury rates of 22-67% among women and similar rates for men during basic training across different service branches 1
- Overuse pattern: The repetitive, high-volume nature of military physical training (running, marching with loads) creates the exact conditions that exacerbate flatfoot-related biomechanical abnormalities
- Limited recovery time: Military training schedules often don't allow adequate recovery between high-impact activities
Long-term Functional Outcomes
The severity of symptom aggravation is underscored by surgical outcome data: Among active duty military personnel who underwent reconstructive surgery for symptomatic pes planus, 96% failed to return to their preinjury level of function, and 40% faced separation from the military 4. This represents the most severe end of the spectrum but illustrates how military demands can render even surgically corrected flatfoot incompatible with service requirements.
Comparative Evidence
Epidemiological data confirms that flatfoot deformity and arthritis are significantly more prevalent in veterans versus nonveterans 5, suggesting that military service has lasting effects on foot structure and function beyond active duty.
Clinical Implications
Common pitfall: Assuming asymptomatic pes planus will remain asymptomatic during military service. The evidence clearly shows that the transition to military training represents a critical period where previously compensated flatfoot becomes symptomatic.
Key Considerations:
- Most foot and ankle disorders in military populations occur within the first 2 months of service 2
- The injury burden results in substantial limited duty days (129 injury-related limited duty days per 100 female trainees per month in one Army study) 1
- Smoking, flatfoot deformity, and previous injuries were all statistically significant risk factors for foot and ankle disorders 2
Caveat on Conflicting Evidence
One Australian Air Force study found that foot shape had little impact on injury rates during 10-week basic training 6. However, this shorter observation period and different training intensity may not capture the cumulative effect seen in longer-term U.S. military studies. The preponderance of evidence from multiple U.S. military cohorts and the Finnish conscript study supports that pes planus does increase injury risk.
Bottom Line for Clinical Practice
When counseling individuals with pes planus considering military service, inform them of the substantial risk of symptom development or worsening, particularly during initial training phases. Prophylactic interventions (appropriate footwear, orthotic support, pre-conditioning programs) should be maximized before service entry, though even these measures may not prevent symptom aggravation given the extreme physical demands of military training.