• Universitat de València
• Foundation for the Promotion of Health and Biomedical Research of the Valencian Community (FISABIO)

• Patricia Gómez Barberó
• Daniel Montaner Alonso
• José Luis Rodrigo Pérez

Following impact to the hand or wrist, scaphoid fractures are the most common, accounting for 80% of carpal fractures. The importance of correct diagnosis and treatment in the acute phase is fundamental for its prognosis and evolution, since untreated or incorrectly managed injuries to this bone will have long-term complications such as the absence of consolidation or pseudoarthrosis, avascular necrosis (in up to 50% of cases) or chronic instability that will progressively lead to the development of carpal osteoarthrosis. In cases where standard interventions with bone grafts have failed, there is only the possibility of a salvage intervention where the wrist is fixed, but the carpal kinematics are completely sacrified.

Researchers from FISABIO (Foundation for the Promotion of Health and Biomedical Research of the Valencian Community) and the Universitat de València (UV) have designed a model of partial scaphoid prosthesis that only replaces the proximal necrotic part, preserving the distal third of the scaphoid. In this way, the distal fragment of scaphoid bone serves as proximal anchorage of the implant and allows the reconstruction of the dorsal and palmar scapho-lunate ligament.

The new prosthesis simulates both in dimensions and morphology the anatomical scaphoid and has been designed in three sizes that adapt to any patient with the aim of relieving pain and maintaining the greatest possible range of mobility and strength, and therefore will not lead in the future to carpal collapse and carpal osteoarthrosis.

The indication for this arthroplasty in clinical practice would be in cases of recalcitrant pseudoarthrosis of the scaphoid, its avascular necrosis, Preiser's disease, some acute fractures with great comminution or displacement where it is impossible to perform an anatomical reduction and primary osteosynthesis or in cases of incipient arthrosis of the wrist secondary to advanced collapse due to pseudoarthrosis of the scaphoid (SNAC).

Companies in the traumatology and orthopaedics sector with the capacity to manufacture in biocompatible material.

• They have been developed in sizes that adapt to all anatomies and therefore manufacturing can be standarised.
• The surgical technique to be used is the usual one, so its implantation in clinical practice would be simple.
• It is an anatomical prosthesis, the design, unlike those that currently exist, takes into account the rest of the carpal bones with which the scaphoid articulates, maintaining dimensions and correct joint congruence.
• It allows the patient a great range of movement and strength. Therefore, avoiding collapse and carpal arthrisis caused by lack of mobility.
• By not completely replacing the scaphoid, it respects the extrinsic ligaments of the wrist which play an important role in carpal kinematics during different movements, especially in the dart throwing movement.
• By anchoring the prosthesis to the scaphoid itself, the bone acts as a single block mimicking the previous movement of the scaphoid.
• It avoids second surgeries. Many prostheses act as spacers, i.e. they are placed where the damaged bone was previously located and fill its space to prevent collapse. Since these systems are not fixed to other carpal bones, they tend to flex and subluxate dorsally, requiring a second surgical procedure to remove them.

• Patent applied