Quadriceps Muscle Atrophy

Severe muscle disability (per § 4.56(d)(4)): through-and-through or deep penetrating wound by small high-velocity missile or large low-velocity missile, with extensive debridement, prolonged infection, or sloughing of soft parts. Objective findings: ragged / depressed / adherent scars; loss of deep fascia, muscle substance, normal firm resistance; palpable evidence of weakened contraction. For atrophy specifically, this tier applies to severe disuse atrophy from prolonged immobilization, denervation, or post-traumatic loss of muscle bulk with documented strength deficit >50% versus contralateral side.

Moderately Severe muscle disability (per § 4.56(d)(3)): through-and-through or deep penetrating wound with debridement, prolonged infection, or sloughing of soft parts, with intermuscular scarring. Objective: moderate loss of deep fascia / muscle substance / firm resistance; strength testing shows positive impairment. For atrophy: documented loss of muscle bulk (circumferential measurement deficit), strength deficit, and functional limitation in stair-climbing or stand-from-sit.

Moderate muscle disability (per § 4.56(d)(2)): through-and-through or deep penetrating short-track wound from single bullet / small shell / shrapnel fragment, without high-velocity explosive effect or prolonged infection. Objective: small/linear entrance and exit scars; some loss of deep fascia / muscle substance; impaired muscle tonus; lowered threshold of fatigue. For atrophy: mild measurable bulk loss, lowered endurance, but functional preservation.

Slight muscle disability (per § 4.56(d)(1)): simple wound without debridement or infection; minimal scar; no fascial defect, atrophy, or impaired tonus; no functional impairment.