The AnteroLateral Transpsoatic Approach (ALPA)

Prosthetic disc-nucleus devices have traditionally been implanted via the same posterior approach that is standard for lumbar decompression surgery. To avoid disrupting the posterior structures of the spine and to facilitate device implantation, the AnteroLateral transPsoatic Approach (ALPA) has been developed. With ALPA, an incision is made in the lateral region overlying the disc, and the lateroabdominal muscles are bluntly dissected. The retroperitoneal area is accessed and followed to the psoas muscle, where blunt dissection in the direction of the muscle fibers is used to reach the affected disc. The disc anulus is cut to create a flap, the nucleus pulposus material is removed, and the prosthesis is implanted into the disc cavity. The procedure concludes with the anulus flap being sutured in place over the opening to the nucleus, and the wound is closed in a normal manner. A small study group of eight patients has been implanted with PDN prosthetic disc-nucleus devices by way of the ALPA technique. Preliminary results indicate minor adverse events related to the surgical technique. Clinical results are also encouraging with significant improvements in Oswestry and Prolo scores and with an associated increase in disc height. The ALPA technique is a good alternative to the posterior hemilaminotomy approach for implanting nucleus devices in degenerated lumbar discs.