Shin Splints / Medial Tibial Stress Syndrome (MTSS) Secondary to Pes Planus (Flat Feet)

Yes. Under 38 CFR § 3.310(a), any disability proximately caused or chronically worsened by a service-connected condition is itself service-connected. Shin Splints / Medial Tibial Stress Syndrome (MTSS) is a documented secondary pairing for Pes Planus (Flat Feet) with strong medical evidence. A nexus letter from a qualified physician linking the two conditions is the most reliable way to establish this connection.

The gold standard is a private nexus opinion stating — to at least a 50% probability ("at least as likely as not") — that the secondary condition was caused or aggravated by the primary service-connected condition. Peer-reviewed medical literature supporting the physiological mechanism strengthens the nexus. Treatment records documenting the onset or worsening of the secondary condition in temporal relation to the primary are supporting evidence.

The VA rates Shin Splints / Medial Tibial Stress Syndrome (MTSS) separately under its own 38 CFR Part 4 diagnostic code, then combines it with Pes Planus (Flat Feet) and all other service-connected ratings using the combined ratings formula under § 4.25. The formula applies the whole-person concept: a 50% combined existing rating plus a new 30% rating yields 65% (rounded to 70%), not 80%.

38 CFR § 3.310(a) states: "Disability which is proximately due to or the result of a service-connected disease or injury shall be service connected." The aggravation variant under § 3.310(b) applies where the primary condition permanently worsens a pre-existing disability beyond its natural progression. Both standards require a showing of nexus — a medical or scientific link between the primary condition and the secondary.

The medical evidence supporting Shin Splints / Medial Tibial Stress Syndrome (MTSS) as secondary to Pes Planus (Flat Feet) is rated strong. Pes planus causes excessive pronation that increases traction forces on the deep posterior compartment muscles (tibialis posterior, flexor digitorum longus, flexor hallucis longus) at their tibial periosteal attachments. This repetitive periosteal loading produces medial tibial stress syndrome — periostitis of the posteromedial tibial border. The flat foot morphology also increases ground reaction force transmission through the tibial shaft due to diminished shock absorption from the collapsed arch. Prospective military cohort studies consistently identify pes planus as the strongest independent risk factor for MTSS, with flat-footed recruits showing 3-4x higher incidence during basic training. Chronic MTSS can progress to tibial stress fractures if untreated.

The VA will not solicit nexus evidence on your behalf for secondary claims. In practice, a written nexus opinion from a private physician or independent medical examiner is essential — the VA's Compensation & Pension (C&P) examiner is not required to produce a favorable nexus opinion, and the VA has discretion to weigh competing opinions. Submitting a private nexus letter at the time of filing is the most reliable strategy.