The minimally invasive interbody selection algorithm for spinal deformity.

Area of Science:

• Spine surgery
• Orthopedic surgery
• Minimally invasive spinal techniques

Background:

• Minimally invasive surgery (MIS) is crucial for spinal deformity correction, decompression, and arthrodesis.
• Current selection criteria for specific interbody approaches in MIS for spinal deformity are lacking.
• A structured decision-making framework is needed for rational surgical planning.

Purpose of the Study:

• To develop and validate the minimally invasive interbody selection algorithm (MIISA) for MIS spinal deformity surgery.
• To provide a rational framework for selecting among anterior lumbar interbody fusion (ALIF), anterior column release (ACR), lateral lumbar interbody fusion (LLIF), and transforaminal lumbar interbody fusion (TLIF).

Main Methods:

• Retrospective analysis of circumferential MIS (cMIS) for adult spinal deformity (ASD) over 5 years.
• Surgeon preferences and segmental lordosis outcomes were evaluated at each lumbar level.
• A Delphi session with minimally invasive deformity surgeons informed algorithm creation.
• Comparison of preoperative and 2-year postoperative radiographic and clinical outcomes.

Main Results:

• The MIISA was developed with substantial agreement among 11 surgeons performing 100 cMISs.
• Surgeons preferred LLIF for L1-4, with ACR used for greater lordosis needs.
• At L4-5, preferences were LLIF, TLIF, and ALIF; at L5-S1, ALIF and TLIF were preferred.
• ALIF and ACR demonstrated significant lordosis restoration, while LLIF alone did not.

Conclusions:

• The MIISA offers consistent guidance for MIS spinal deformity surgery.
• The algorithm prioritizes lateral approaches for upper lumbar levels and reserves ACR for significant lordosis correction.
• Specific interbody choices at L4-5 and L5-S1 depend on desired lordosis restoration.