Masked rotatory subluxation of the atlas associated with fracture of the clavicle: a clinical and biomechanical analysis.

We report on two children who developed a fixed rotatory subluxation of the atlantoaxial joint due to torticollis being attributed to a fractured clavicle. Appropriate treatment was delayed for weeks to months; only after the fractured clavicle had healed and the torticollis persisted was the problem identified. Persisting rotatory subluxation also predisposes to further anterior displacement of C-1 due to an increased moment arm created by the forward displacement of the center of gravity of the head. The association of atlantoaxial subluxation should always be considered in children presenting with a clavicular fracture and an acute torticollis.