Rotational Stability of Scaphoid Waist Nonunion Bone Graft and Fixation Techniques
Jacob D Gire1, Timothy Thio1, Anthony W Behn1
1Chase Hand and Upper Limb Center, Department of Orthopaedic Surgery, Stanford University School of Medicine, Redwood City, CA.
Purpose:
Rotational instability of scaphoid fracture nonunions can lead to persistent nonunion. We hypothesized that a hybrid Russe technique would provide improved rotational stability compared with an instrumented corticocancellous wedge graft in a cadaver model of scaphoid nonunion.
Methods:
A volar wedge osteotomy was created at the scaphoid waist in 16 scaphoids from matched-pair specimens. A wedge was inset at the osteotomy site or a 4 × 16-mm strut was inserted in the scaphoid and a screw was placed along the central axis (model 1). The construct was cyclically loaded in torsion until failure. The screw was removed and the proximal and distal poles were debrided. A matching wedge and packed cancellous bone graft or an 8 × 20-mm strut was shaped and fit inside the proximal and distal pole (model 2). A screw was placed and testing was repeated.
Results:
In the first model, there was no significant difference in cycles to failure, target torque, or maximal torque between the strut graft and the wedge graft. Cycles to failure positively correlated with estimated bone density for the wedge graft, but not for the strut graft. In the second model, the strut graft had significantly higher cycles to failure, greater target torque, and higher maximal torque compared with the wedge graft. The number of cycles to failure was not correlated with estimated bone density for the wedge or the strut grafts.
Conclusions:
The hybrid Russe technique of inlay corticocancellous strut and screw fixation provides improved rotational stability compared with a wedge graft with screw fixation for a cadaver model of scaphoid waist nonunion with cystic change.
Clinical Relevance:
The hybrid Russe technique may provide better rotational stability for scaphoid waist nonunions when the proximal or distal scaphoid pole is compromised, such as when there is extensive cystic change, when considerable debridement is necessary, or with revision nonunion surgery.
