Prótesis de cuerpo vertebral JR: dispositivo modular, anatómico y expandible, con función de jaula y placa dise？ada ad hoc para estabilizar la columna después de corpectomía

introduction: due to the unsatisfactory results obtained with posterior instrumentations in cases of vertebral tumors and to the economical limitations of our patients for acquiring the systems available in the market, a vertebral body prosthesis to stabilize the spine after corpectomy was designed. objective: to describe the structural and functional characteristics of the jr prosthesis, the biomechanical assays in cadaver and the surgical technique on the patient. methods: firstly, it was performed a detailed anatomical study of the vertebral bodies. a design of a modular, anatomical and expandable device was obtained. its components once assembled make an implant with expandable cage and plate dual function. afterwards, a biomechanical assay was performed in a cadaver and the device was implanted in a patient with vertebral body metastasis. results: the radiographs extracted from the cadaver after implant location did not show loss of fixation. when the cadaver was raised, flexion moments were generated laterally with levers 80 cm long; therefore, the prosthesis was demanded in its most vulnerable point with a force of approximately 588 n. with rotation, flexion and extensions forced, stability was preserved and no movement was observed. the device was implanted in a 50-year-old woman with metastatic thyroid cancer affecting l3. pain improved in the postoperative immediate, as well as its motor function, which allowed her to walk with a stable and painless spine for seven years. no implant failure was observed. conclusion: the dual cage function and plate integrated in a single device offers a mechanical advantage, compared with the cages and plates used separately, since the prosthesis design permits to apply a distraction axial force with lateral fixation at the same time, through one implant. the results of the implant placement in the patient were satisfactory.