History of Integral Fixation for Anterior Lumbar Interbody Fusion (ALIF): The Hartshill Horseshoe

OBJECTIVE: Anterior lumbar interbody fusion (ALIF) is a common spinal fusion option for different spinal pathologies. In the early years, implant migrations/expulsions were potential complications of ALIFs due to the lack of integral fixation. We present a historical vignette on the inception and development of the first stand-alone ALIF (SA-ALIF) implant-the Hartshill Horseshoe (HH). METHODS: A Preferred Reporting Items for Systematic Reviews and Meta-Analyses systematic search was carried out for 3 online databases focusing on implant development for ALIF, refining the search to before 1995. A personal communication with the original patent holders of the HH was used due to the lack of formal publication of the HH during its early years. RESULTS: Since 1932, the idea of anterior lumbar fusion was proposed and was carried out in 1933 using a tibial peg. Autografts were first reported in 1936 as interbody spacers for ALIF. Since then, bone grafts were commonly used for ALIF. However, ALIFs were not commonly performed due to variable reported outcomes. A pilot study in 1971 reported the use titanium mesh blocks as interbody implants in 6 patients. No articles reporting the use of integral fixation for SA-ALIF implants were found before the development of the HH in 1984. CONCLUSIONS: The HH was the first synthetic SA-ALIF implant developed. Since the HH, multiple SA-ALIF implants have been designed. The benefits of integral fixation in a SA-ALIF device include immediate implant stability, ability to reduce and correct deformity postimplantation, prevention of implant migration, and increased implantLbony endplate contact for early osseointegration.