Morphometric Assessment of the Residual Width of the Distal Hamate Articular Surface after Graft Harvest for Hemi-hamate Arthroplasty

Background: The hemi-hamate arthroplasty (HHA) can restore joint congruity and stability in chronic fracture-dislocations of the proximal interphalangeal joint (PIPJ). Purpose of this study was to compare the width of the distal hamate articular surface (DHAS) to the width of the base of the middle phalanges (P2) of the fingers. We hypothesized the dimensions of the width of the DHAS would be similar to those of P2, leaving a small amount of residual DHAS width after autograft harvest. Methods: Fifty-nine CT scans of the hand without any bony pathology were evaluated. Three observers measured the following parameters and compared: (a) Width of the DHAS in the axial and coronal planes; (b) Width of the P2 articular bases of all four fingers; (c) Maximum capitate length (MaxCap) in the coronal plane. Results: The residual DHAS on the coronal plane after graft harvest (bone remaining on the radial and ulnar aspects each, not accounting for saw blade or osteotomy width thickness) among all patients was 1.3, 0.9, 1.4, and 2.4 mm for the index, long, ring and small fingers respectively. There was a strong correlation between DHAS and MaxCap r=0.76. Conclusion: There is likely to be a very small amount of residual hamate articular surface width left after the graft is harvested if the entire base of P2 is reconstructed.