Which is the Best Solution for Achieving Maximal Interfragmentary Compression of the Scaphoid Fractures - One or Two Herbert Screws?

PURPOSE OF THE STUDY To compare the treatment outcome of scaphoid facture fixation with one versus two Herbert screws (HBS). MATERIAL AND METHODS 72 patients underwent open reduction internal fixation (ORIF) following acute scaphoid fracture, and were followed prospectively by one surgeon. All fractures were Herbert & Fisher classification type B, the most common fracture lines being oblique (n=38) and transverse (n=34). Fractures with similar fracture lines were randomly assigned into two groups; fractures stabilized with one HBS (n=42) and fractures stabilized with two HBS (n=30). A specific methodology was developed for placement of two HBS; in the case of transverse fractures, screws were introduced perpendicular to the fracture line, for oblique fractures the first screw was placed perpendicular to the fracture line and the second screw was placed along the longitudinal axis of the scaphoid. RESULTS Patients were followed for a total 24 months, no patients were lost to follow-up. Outcome measures included bone healing, duration to bone healing, carpal geometry, range of motion (ROM), grip strength, and the Mayo Wrist Score. Patient rated outcomes were measured using DASH. Bone healing was radiographically and clinically confirmed in 70 patients. There were two non-unions after fixation with one HBS. Radiographic angles in both groups did not differ significantly from the physiological values. The mean duration to bone union was 1.8 months for one HBS and 1.5 months for two HBS. Mean grip strength was 47 kg in the group with one HBS (16-70 kg), 94 % of the unaffected hand, and 49 kg in the group with two HBS, 97% unaffected hand. The average Visual Analog Scale (VAS) score for the group with one HBS was 2.5, while for the group with two HBS was 2.0. Both groups had excellent and good results. For the group with two HBS, they are more. (100% for those fixed with two HBS and for those fixed with one HBS = 95% excellent and good and 5% bad results). DISCUSSION A review of the literature confirms that the addition of the second screw increases the stability in the scaphoid fractures by offering added resistance to torque forces. Most authors propose the parallel placing of both screws in all cases. In our study we offer an algorithm for the placement of screws depending of the type of fracture line. For transverse fractures screws are placed parallel and perpendicular to the fracture line, for oblique fractures the first screw is placed perpendicular to the fracture line, and the second screw is placed along the longitudinal axis of the scaphoid. This algorithm covers the main laboratory requirements for maximal fracture compression depending of the fracture line. CONCLUSIONS This study of 72 patients in whom patients with similar fracture geometry were separated into two groups fixed by one HBS and fixed by two HBS. Analysis of the results demonstrate that osteosynthesis with two HBS creates greater fracture stability. The proposed algorithm for fixation of acute scaphoid fractures using two HBS is achieved by simultaneously placing the screw along the axial axis and perpendicular to the fracture line. The stability is improved by the equal distribution of the compression force on the entire fracture surface. Key words: scaphoid fractures, Herbert screw, two screws fixation.