Cast immobilization with and without immobilization of the thumb for nondisplaced and minimally displaced scaphoid waist fractures: a multicenter, randomized, controlled trial.

PURPOSE: The aim of this prospective randomized trial was to test the null hypothesis that there was no difference in the percentage of the fracture line of scaphoid waist fractures that demonstrated bridging bone on computed tomography (CT) 10 weeks after injury between patients treated in a below-elbow cast including or excluding the thumb.

METHODS: A total of 62 patients with a CT or magnetic resonance image-confirmed nondisplaced or minimally displaced fracture of the scaphoid were enrolled in a prospective, multicenter, randomized trial comparing treatment in a below-elbow cast including or excluding the thumb. There were 55 waist and 7 distal fractures (owing to a miscommunication at 3 of the centers). We adhered to intention-to-treat principles. The primary outcome was the extent of union on CT performed after 10 weeks of cast treatment, expressed as a percentage of the fracture line that had bridging bone, determined by musculoskeletal radiologists blinded to treatment. Secondary study outcomes included wrist motion; grip strength; the Mayo Modified Wrist Score; the Disabilities of the Arm, Shoulder and Hand score; a visual analog scale for pain; and radiographic union at 6 months after injury.

RESULTS: There was a significant difference in the average extent of union on CT at 10 weeks (85% vs 70%) favoring treatment with a cast excluding the thumb. The overall union rate was 98%. The 1 exception was a patient in the thumb immobilization group who elected operative treatment 1 week after enrollment, used crutches, and failed to heal. There were no significant differences between groups for wrist motion; grip strength; Mayo Modified Wrist Score; Disabilities of the Arm, Shoulder, and Hand score; or pain intensity.

CONCLUSIONS: Immobilization of the thumb appears unnecessary for CT or magnetic resonance image-confirmed nondisplaced or minimally displaced fractures of the waist of the scaphoid.

TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic I.