[Interbody fusion procedures. Development from a historical perspective].

Background: The development of interbody fusion now stretches over many decades and is still not complete.

Discussion: Due to the lack of appropriate implants, the initial fusions were performed via decortication of the dorsal and lateral structures of the spine, followed by placement of an autograft. Despite acceptable fusion results, better primary stability and higher fusion rates were desired. In addition, it became known that the primary load-bearing of the spine is located ventrally in the area of the corpus of the vertebrae. These considerations led to the development of the PLIF technique that was introduced by Cloward in 1953 and gained significantly in popularity. After removal of the intervertebral disc, he positioned iliac crest bone blocks between the vertebral bodies. Based on this technique and these considerations, intervertebral implants were developed in the 1970s. The so-called Bagby Basket was the first intervertebral cage that was initially used in horses with wobbler syndrome. Other milestones in the improvement of the cage designs followed, resulting in the production of different implant shapes and materials. The elastic modulus of the interbody implants approached by modern materials became more and more similar to bone, so that subsidence of cages reduced and the fusion rate could be further increased. The primary stability could be further increased with screw-rod systems, so that dorsal instrumentation became the standard in the context of PLIF and TLIF procedures today. The TLIF procedure described by Harms was a new modification and minimized complications of lumbar fusions and reduced the invasiveness of the procedure.

Conclusion: Nowadays a wide variety of implants and implantation techniques are available, making interbody fusions in PLIF and TLIF techniques safe and successful procedures.