For suspected scaphoid fractures with negative radiographs it is common practice to put a person in a short arm thumb spica splint until followup up radiographs can be obtained in 10-14 days.
However, there is evidence that a short arm thumb spica splint is not enough for people that have a true scaphoid fracture. Gellman et al demonstrated that long arm thumb-spica cast immobilization for six weeks followed by short arm thumb-spica cast immobilization decreased time to union by 25% when compared to short arm thumb-spica casting alone.
The theory is that the short arm splint still allows for forearm rotation that can cause shearing motion of the volar radiocarpal ligaments. A long arm splint prevents this shearing action. The disadvantage of a long arm splint though is potential elbow joint stiffness and muscle atrophy that can occur during the prolonged period of immobilization.
So for your next patient with a scaphoid fracture seen on radiographs place them in a long arm thumb spica splint.
References
Gellman H, Caputo RJ, Carter V, Aboulafia A, McKay M. Comparison of short and long thumb-spica casts for non-displaced fractures of the carpal scaphoid. J Bone Joint Surg Am. 1989; 71:354-357.
Lawton JN, Nicholls MA, Charoglu CP. Immobilization for Scaphoid Fracture: Forearm Rotation in Long Arm Thumb-spica Versus Munster Thumb-spica Casts. Orthopedics 2007; 30:612
