An Anthropometric Assessment of Proximal Hamate Autograft for Scaphoid Proximal Pole Reconstruction
Kitty Wu, MD; Clare Padmore, MEng; Emily Lalone, PhD; Nina Suh, MD, FRCSC
Roth McFarlane Hand & Upper Limb Centre, London, ON, Canada
Introduction
Fragmentation of the scaphoid proximal pole presents a difficult surgical problem. This can occur secondary to avascular necrosis following traumatic proximal pole fractures or Preiser's disease. This anthropometric study assesses the fit of the ipsilateral proximal hamate for use as autologous bone graft for scaphoid proximal pole reconstruction.
Materials & Methods
Twenty-nine cadaveric specimens underwent computed tomography and 3-D reconstruction of the carpus and distal radius. The scaphoid height was measured and a third of its height was used to simulate resection of the proximal pole of the scaphoid and extent of hamate osteotomy. The proximal scaphoid and hamate were divided into 6 sections for comparison (Figure 1). These 6 areas were compared using an iterative point-to-point distance algorithm to determine average distance between the surfaces. An inter-bone algorithm was used to assess radioscaphoid joint congruency with proximal hamate autograft.
Results
The mean scaphoid height was 27.9mm and mean divided proximal pole and proximal hamate height was 9.3mm. The mean distance was the largest in the dorsal scaphocapitate (0.675mm), volar radioscaphoid (0.736mm), and dorsal radioscaphoid segments (0.751mm). Without osteotomy, the hamate autograft may cause impaction in the dorsal-radial aspect of the distal radius. Nine hamate autografts with mean distances greater than 1mm were classified as poor-fitting. Poor-fitting specimens had a greater radial styloid to DRUJ distance (mean 32.3mm, p = 0.004). These specimens also had wider hamates and scaphoids in the radial-ulnar dimension (mean 12.6mm, p = 0.007; mean 10.9mm, p = 0.004 respectively) and wider scaphoids in the volar-dorsal dimension (mean 18.6mm, p = 0.0005). The hamate autograft shifted the centroid of the radioscaphoid joint towards the dorsal-radial position.
Conclusions
The proximal hamate autograft for scaphoid proximal pole reconstruction may be considered in patients with DRUJ-radial styloid distance of less than 32mm. Patients with radial-ulnar hamate width less than 10mm, radial-ulnar scaphoid width less than 10mm, and volar-dorsal scaphoid width less than 16mm demonstrates better anthropometric fit.
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