A Spine Surgeon’s Learning Curve With the Minimally Invasive L5 to S1 Lateral ALIF Surgical Approach: Perioperative Outcomes and Technical Considerations

BACKGROUND: Lateral anterior lumbar interbody fusion (L-ALIF), or oblique lumbar interbody fusion at L5 to S1 (OLIF51), is a minimally invasive approach between the iliac vessels that provide indirect decompression, alignment restoration, and lordosis. While supine ALIF exposure has historically been performed by vascular surgeons, minimally invasive L-ALIF can be performed by spine surgeons familiar with lateral approaches. The L-ALIF is a relatively newer approach, and the objective of the present study was to assess the learning curve of the L-ALIF approach by comparing the pre- and postoperative radiographic measurements, patient-reported outcome measures (PROMs), and complications in a surgeon's first 25 L-ALIF patients compared with the subsequent 25 L-ALIF patients. METHODS: This retrospective case series includes the first 50 OLIF patients at/or including L5 to S1 by 1 surgeon. Demographics, complications, PROMs, and clinical and radiographic results were collected, and patients were analyzed comparing the surgeon's first 1 to 25 patients (group A) and last 26 to 50 patients (B). RESULTS: Demographic analysis demonstrated a mean age of 59.7 years and a body mass index of 28.7, and 52% of participants were women. The diagnosis was degenerative disc disease in 36 patients and deformity in 14 patients. Fourteen patients underwent single interbody level fusions at L5 to S1, 21 with 2 levels, and 15 with 3 to 6 levels. Segmental L5 to S1 lordosis increased 9.6° ± 3.9°, final mean lordosis 25.3° ± 8.3°; L5 to S1 disc angle increased 11.5° ± 4.9°, final disc angle 19.7° ± 3.8°; posterior disc height increased 3.6 mm ± 2.1 mm with final mean disc height 7.6 mm ± 1.8 mm. PROMs postoperatively were significantly improved from preoperatively. There were no significant differences in operative times for degenerative 1- or 2-level single-position surgery operations between groups A and B. Two group A patients had incisional hernias requiring repair, and 2 group B patients had postoperative ileus. There were no approach-related injuries. CONCLUSION: With proper patient selection and meticulous technique, the minimally invasive L-ALIF at L5 to S1 can be performed by surgeons experienced with lateral approaches to other spine levels. This study provides level 4 evidence and low-quality evidence in the Grading of Recommendations Assessment, Development, and Evaluation framework. CLINICAL RELEVANCE: The lateral ALIF is a safe and effective approach at L5 to S1 for spine surgeons and provides good clinical, biomechanical, and radiographic outcomes, especially for those who do not have access surgeons available. Close attention to left common iliac vein anatomy is paramount for this type of approach and similar to other approaches. With increased repetition and numbers of cases, surgeons are able to improve in their technique.