A Morphometric Analysis of Hamate Autograft for Proximal Scaphoid Reconstruction

Objective Recently, authors have investigated using the proximal hamate as osteochondral autograft for proximal pole scaphoid reconstruction in the case of nonunion with avascular necrosis. The aim of our study was to analyze the morphology and anatomic fit of the proximal hamate compared with the proximal pole of the scaphoid using cadaveric specimens. Materials and Methods Ten cadaver specimens (five males and five females) were dissected. Scaphoid and proximal hamate bones were measured by two independent investigators using electronic calipers and radius of curvature gauges. After measurements were determined to have good correlation, the average value of the two observers' measurements were used for further analysis. Sagittal radius of curvature (ROC), coronal ROC, depth, width, and maximum graft length were compared. Results The average depth of the scaphoid proximal pole was 12.3 mm (standard deviation [SD] = 1.12) compared with 11.3 mm (SD = 1.24) for the proximal hamate (p = 0.36). The average width was 7.8 mm (SD = 1.00) in the scaphoids compared with 8.6 (SD = 1.05) in the hamates (p = 0.09). There was also no significant difference in the sagittal ROC between hamates (9.1 mm, SD = 1.13) and scaphoids (9.5 mm, SD = 0.84; p = 0.36). All of these average measurements were within 1 mm. There was a significant difference between the coronal ROC of the hamate (23.4 mm) and scaphoid (21.1 mm) bones in our samples (p = 0.03). Females were on average smaller than their males, but there was no significant difference in fit based on sex alone. Conclusion The proximal pole of the hamate has similar morphology and size as the scaphoid, with similar depth, width, and sagittal ROC. It has potential as an osteochondral autograft for proximal pole scaphoid reconstruction.

Scapho-Capitate Ratio for Estimation of Scaphoid Length

Background: The failure of scaphoid reconstruction by restoring both length and shape may lead to carpal mal-alignment and progressive degenerative arthritis. The aim of our study is to find a reliable method to find out the scaphoid length without measuring the contralateral scaphoid. Methods: Three X-ray wrist views were collected for 51 patients without any signs suggesting any hand and wrist fractures. The scaphoid, capitate and 3rd metacarpal bone axes lengths and carpal height were measured by 4 hand surgeons separately. Results: The scapho-capitate ratio was 1.1 ± 0.084, 1.01 ± 0.084 and 0.92 ± 0.109 for lateral, postero-anterior with ulnar deviation and postero-anterior view respectively. The ulnar deviation view had the highest reliability. Conclusions: Scapho-capitate ratio estimation is an easy and accurate measure of normal scaphoid length in situations when the scaphoid is short. It is helpful for the estimation of the size of the bone graft that need for reconstruction of the scaphoid.

The Effect of Proximal Hamate Osteotomy on Carpal Kinematics for Reconstruction of Proximal Pole Scaphoid Nonunion With Avascular Necrosis

Background: The purpose of this study is to determine the effects of proximal hamate transfer for proximal pole scaphoid reconstruction upon carpal kinematics. Methods: Eight fresh-frozen cadaveric wrists underwent evaluation of their radiocarpal and midcarpal motion after proximal hamate osteotomy. A wrist simulator was used to apply cyclical tension to the flexor carpi ulnaris (FCU), flexor carpi radialis (FCR), extensor carpi ulnaris (ECU), and extensor carpi radialis longus and brevis stitched together (ECR). Kinematic motion was captured using Moiré Phase Tracking 3-dimensional motion-tracking sensors (MPT, Metria Innovation, Inc, Milwaukee, Wisconsin) to evaluate the lunocapitate and scapholunate angles for each condition. Results: During wrist flexion-extension and radial-ulnar deviation, there were no statistically significant differences about the lunocapitate or scapholunate axis between the intact and post-hamate osteotomy conditions. Conclusions: The harvest of the proximal hamate for proximal pole scaphoid reconstruction does not appear to adversely affect wrist kinematics.

Vascularized versus non-vascularized bone grafts in the treatment of scaphoid non-union

Introduction: Conventional non-vascularized bone grafts as well as vascularized bone grafts are used to treat scaphoid non-union (SN). Due to limited available studies, the field of application using both grafts for SN still remains controversial. The aim of this study was to evaluate a treatment algorithm for the use of both vascularized versus non-vascularized bone grafts based on clinical outcomes and quality of life (QoL) to improve the level of evidence. Materials and Methods: Based on a retrospective cohort study, including 28 patients with vascularized and 45 patients with conventional bone grafts, functional parameters, radiological outcome, Mayo-wrist-score, and QoL by SF-36 were applied to statistically compare the outcome of these two techniques. Results: Time between last procedure or trauma and study group scaphoid reconstruction was almost double in the vascularized bone grafting group. Comparable union rates were achieved with vascularized as well as non-vascularized bone grafts. Significant differences were observed between both groups for grip strength and radial-ulnar active range of motion. Further functional outcomes, radiological outcomes as well as QoL were found similar for both techniques in patients with surgical union. Discussion and conclusions: In order to achieve comparable and appropriate treatment results, vascularized bone grafts are recommended for patients with delayed treatment, impaired scaphoid vascularity, and revision surgery. Even in preselected, complex cases, the results are comparable to conventional grafts, which are the basis for further patient education and approve the powerful role of surgical angiogenesis of vascularized bone grafts.

Proximal Scaphoid Pole Reconstruction Utilizing Ipsilateral Proximal Hamate Autograft

Background: Fractures of the proximal pole of the scaphoid can be difficult to heal because of its limited vascular supply. Furthermore, nonunion with avascular necrosis and secondary fragmentation makes surgical reconstruction a challenging procedure. Method: We describe a technique and report the outcome of a proximal hamate autograft to treat a proximal pole scaphoid nonunion with avascular necrosis. Results: At 3.5 years post reconstruction, the patient remains asymptomatic with union of his scaphoid reconstruction without any evidence of scapholunate instability. Conclusion: Proximal hamate autograft is a useful technique for addressing proximal pole scaphoid nonunions with avascular necrosis.