Allam and Tossy:
Grade 1: mild sprain, normal radiograph, increased T2 signal on MR.
Grade 2: moderate sprain, less than 50% on radiograph, fluid outside joint capsule on MR.
Grade 3: complete disruption, widening of joint with more than 50% displacement on radiograph, displacement.
Rockwood:
Type I: mild AC ligament sprain, intact CC ligament, joint capsule, deltoid, trapezius muscle, no clavicle elevation.
Type II: ruptured AC ligament, sprained CC ligament, ruptured joint capsule, minimally detatched deltoid and trapezius, clavicle less than 50% of joint height
Type III: ruptured AC and CC ligament and joint capsule, detached trapezius and deltoid, clavicle elevated more than 50% of joint height
Type IV: III + clavicle displaced posteriorly into trapezius
Type V: III + clavicle elevated superiorly more than 100% of joint height.
Type VI: III + clavicle inferiorly displaced behind coracobrachialis and biceps tendons
