Achilles Tendinitis / Tendinopathy 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. Achilles Tendinitis / Tendinopathy 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 Achilles Tendinitis / Tendinopathy 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 Achilles Tendinitis / Tendinopathy as secondary to Pes Planus (Flat Feet) is rated strong. Pes planus causes excessive and prolonged pronation during the stance phase of gait, which places abnormal tensile and torsional loads on the Achilles tendon. The calcaneal eversion associated with flat feet increases the medial bowstringing force on the Achilles, creating non-uniform stress distribution across the tendon cross-section. This asymmetric loading exceeds the tendon's collagen remodeling capacity, leading to insertional tendinopathy, paratenon thickening, and intratendinous degeneration. Biomechanical studies using force plates and motion capture demonstrate 23-35% greater peak Achilles tendon strain in flat-footed individuals compared to neutral arch controls. Military populations with pes planus and high physical demands (running, rucking, jumping) have accelerated tendon degradation.

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.