PURPOSE: This study was designed to morphometrically assess the base of the little and ring finger metacarpals as potential osteochondral donors to resurface distal condylar defects of the proximal phalanx.
METHODS: The proximal phalanges were dissected from all 4 fingers in 10 cadaveric hands and the following measurements were obtained from the distal condylar surface: anteroposterior height, radial-ulnar width, and radius of curvature. Measurements were obtained from posteroanterior and lateral radiographic views, which were digitized and analyzed using digital imaging software. Comparable measurements were obtained from the base of the small and ring metacarpals.
RESULTS: The anteroposterior dimension of both potential donor metacarpals was large enough to resurface the distal condyles of each of the proximal phalanges; however, this was not true for the radial-ulnar dimensions. The distal ulnar condyle of the long finger proximal phalanx was largest, measuring 4.9 (+/- 0.) mm dorsally and 6.2 (+/- 0.5) mm volarly in the radial-ulnar dimension. Only the small metacarpal base had sufficient stock in the radial-ulnar dimension (9.4 [+/- 1.7]) mm dorsally and 10.6 [+/- 2.0] mm volarly) to resurface this condyle. With respect to radius of curvature (ROC), the donor-to-recipient ROC ratio was 1.43 for the small metacarpal base versus 2.12 for the ring metacarpal base. Linear regression analysis revealed a stronger relationship in ROC between donor and recipient condyle when the small metacarpal base served as the donor (R = 0.96 vs R = 0.60).
CONCLUSIONS: As determined from morphometric measurements of the 2 potential donor sites tested, the base of the small metacarpal provides the best match for resurfacing distal condylar defects of the proximal phalanges
