Suitability of Hamate Autograft for Reconstruction of Scaphoid Proximal Pole Non-Union: Morphometric Analysis in Cadavers
Mary Kathyrn Thayer, MD1; Benjamin Bluth, MD1; Jerry I Huang, MD2; (1)University of Washington, Seattle, WA, (2)Department of Orthopaedics and Sports Medicine, University of Washington Medical Center, Seattle, WA
Surgical treatment of proximal pole scaphoid nonunions is technically challenging in part due to compromised vascularity and often, a very small osteochondral proximal fragment. Reconstruction options include the use of vascularized medial femoral osteochondral grafts and rib costochondral grafts. Our goal was to determine the suitability of using a proximal hamate autograft to reconstruct the proximal pole of scaphoid using cadaveric samples and morphometric analysis.
Ten cadaver specimens (5 male, 5 female) were dissected and morphometric analysis of the proximal poles of the scaphoid and hamate was performed. Measurements were compared between the proximal pole of the scaphoid and hamate for sagittal radius of curvature (ROC), coronal ROC, height, width, and maximum graft length using digital electronic calipers and standard radius gauges [Figure 1]. Statistical analysis was performed using paired StudentŐs t-test. Measurements were performed independently by two of the co-authors. The average value of the two observersŐ measurements were then used for further analysis.
The average height of the scaphoid proximal pole was 12.3mm compared to 11.3mm for the proximal hamate (p=0.36). The average width was 7.77mm in the scaphoids compared to 8.60mm in the hamates (p=0.09). There was no significant difference in the sagittal ROC between the hamate (9.13mm) and scaphoid (9.54mm) (p=0.36). All of these average measurements were within 1mm. There was a larger difference between the coronal ROC of the hamate (23.4mm) and scaphoid (21.1mm) in our cadaveric samples (p=0.03). Female measurements were on average smaller than their male counterparts but there was no decrease in fit between the scaphoid and hamate measurements.
In summary, the proximal poles of the scaphoid and the hamate have similar morphology and size that could be appropriate for autograft use [Figure 2]. The mean measurements of height, width, length, and sagittal ROC were all within 1mm for the hamate and scaphoid. Further clinical studies would be required to determine whether this is an effective surgical treatment for proximal pole of the scaphoid nonunion.
FIGURE 1: Measurements obtained from the cadaveric scaphoid proximal pole and proximal hamate. A and Z are representative of the sagittal arc, E and W represent coronal arc, B and X are measurements of height and D and T are measurements of width.
FIGURE 2: Photograph of a) proximal hamate on the right next to scaphoid on the left and b) hamate on the left with scaphoid on the right, both with standard ruler for size comparison.
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