Proximal Pole Scaphoid Reconstruction Using Proximal Hamate

Recently, A novel surgical technique was illustrated by Elhassan BT et al. in 2016 utilizing the Hemi-hamate autograft for the reconstruction of scaphoid bone proximal pole non-union with avascular necrosis.

The technique showed promising results but is still limited to case reports and anatomical studies

In this study, we aim to:

1. Evaluate the surgical technique steps and suggest any possible modifications to the original description of the technique.
2. Assessment of clinical outcomes of this novel technique in terms of; bone union rate, time to union, and wrist function.
3. Report any complications of the usage of the proximal hamate for the proximal pole of the scaphoid reconstruction.

Almost 70 percent of all carpal bone fractures occur in the scaphoid bone, with an overall incidence of 12 per 100,000 of the general population. About 20 percent of scaphoid bone fractures are in the proximal third of the scaphoid, where the rates of ischemia were reported to be as high as 100 percent.

The risk of avascular necrosis (AVN) and/or non-union that in due course end in arthrosis with the fractures involving the proximal pole of the scaphoid is high and represents a challenging surgical problem, and even more challenging when the proximal pole is fragmented.

Several techniques were described for the surgical management of non-union of the proximal pole of scaphoid, including non-vascularised and vascularized bone grafts, each has characteristic pros and cons. Drawbacks with all of these techniques included donor-site morbidity and/or the requirement of microvascular skill in the case of a vascularized bone graft.

The Hemi-Hamate graft is the closest anatomically and histologically to the scaphoid compared to the rib costochondral and the medial femoral condyle grafts. The proximal part of the hamate has an analogous sizing and morphology to the proximal pole of the scaphoid bone. Both have a similar depth (palmar-dorsal breadth), width (radial-ulnar breadth), and sagittal radius of curvature.

Osteotomized proximal hamate with a maximum graft length at a level proximal to the hamulus distally did not adversely affect the lunate-capitate or the scaphoid-lunate kinematics during the wrist joint flexion-extension and the radial-ulnar deviation.

Since the technique was first described in 2016 only a single case-report study existed in the literature regarding the H-H autograft. Elhassan BT et al. reported that at 3.5-years follow-up the patient was free-pain, the wrist range of motion improved significantly and the Mayo wrist score was 90 which is coherent to an excellent outcome and, no symptoms of midcarpal instability were detected during 3.5-years follow-up.

The first case series published in the literature regarding the use of the Hemi-Hamate autograft was published by Saruhan S et al. in 2021; the study had a limited number of participants (4 cases) and, it was a retrospective study. In these four cases, the union was achieved, the pain was decreased, and there were no signs of donor-site morbidity at the final follow-up.

All probable complications have not been elucidated yet given the infancy stage of the technique description. Therefore, we decided to conduct a prospective case series study to report the outcomes of this newly developed promising technique and outline any possible drawbacks.

The investigators believe that this study will add significantly to the orthopedic literature given the infancy stage of this technique description.

Objectives:

1. Evaluate the surgical technique steps and suggest any possible modifications to the original description of the technique.
2. Assessment of clinical outcomes of this novel technique in terms of; bone union rate, time to union, and wrist function.
3. Report any complications of the usage of the proximal hamate for the proximal pole of the scaphoid reconstruction.

Eligibility Criteria:
Inclusion Criteria:

* Multifragmentary fracture of the proximal pole of scaphoid where fragments cannot be fixated.
* Participants with small and poor-quality proximal pole scaphoid bone fracture after the failure of a previous surgical fixation or bone grafting.

Exclusion Criteria:

* Proximal hamate arthrosis.
* Preexisting midcarpal instability.
* Arthritis at the radioscaphoid joint.
* Large hamate bone (Hamate radial-ulnar breadth greater than 1 cm in a participant with scaphoid bone radial-ulnar breadth less than 1 cm and palmar-dorsal breadth of less than 1.6 cm).