Percutaneous Scaphoid Screw Fixation

Abstract

Hypothesis: Application of a screw to the fractured scaphoid as perpendicular to the plane of the fracture as possible is a key to proper healing. Using the previously proposed radiographic predictor of healing that uses the sum of smaller angles (SSA) of intersection between the proposed screw position and the plane of the fracture in 3 radiographs (posterior anterior [PA] in ulnar deviation, 45 pronation, and supination oblique), we suggested classifying fractures of the scaphoid into volarly accessible “V type” and dorsally accessible “D type” according to the SSA >160° and <160°, respectively. The proximal pole of the scaphoid at the dorsal apex is considered V type and proximal to it is considered D type. Methodology: Prospectively, we fixed the 176 scaphoid fractures percutaneously between 2005 and 2013. The proposed screw passage through the retrograde route was drawn on the 3 mentioned radiographs and the SSA was calculated. We classified 133 fractures (75.6%) as V type (113 waist and 20 proximal pole) and 43 fractures (24.4%) as D type (27 waist and 16 proximal pole). The V type fractures were fixed through retrograde route by cannulated Herbert screw and the D types through antegrade route using mini-incision to protect the extensors and avoid capsular teathering exposing the screw entry. No immobilization was used for both methods and we allowed early range of motion (ROM) exercises a early return to office work. Patients with gross comminution or associated fracture or ligament injury were excluded from this study. Results: In the V type, union occurred in all but one patient (99.2%) at a mean 7.6 weeks (6-12) with no need to supplementary antiglide wire. Two patients with screw prominence in the scaphotrapezial joint needed screw removal after bone union. Five of 85 patients had radiographic scapho-trapezium-trapezoid arthrosis after 5 years, but asymptomatic. In the D type, union occurred in all patients (100%) at a mean 8.1 weeks (6-12). Two patients with screw prominence in the radioscaphoid joint had screw remotion after union; three patients had a painful scar and one had extensor pollicis longus (EPL) adhesions. Both groups had comparable demographics, union rate and time, complication rate, and need for second surgery. Conclusion: Classifying scaphoid into V and D types help the choice of proper fixation route for predictable outcome.