Determining the learning curve for percutaneous endoscopic lumbar interbody fusion for lumbar degenerative diseases

Purpose Percutaneous endoscopic lumbar interbody fusion (PELIF) is one of the least invasive procedures for lumbar degenerative disorders (LDD). There is limited knowledge of the learning curve for PELIF. Methods A total of 93 consecutive patients who underwent PELIF performed by a single spine surgeon for LDD failed with conservative treatment were retrospectively reviewed. The case series was split into three groups based on timing: A (earliest third of patients); B (middle third of patients); and C (latest third of patients). The following were also recorded: operating time, X-ray exposure time, complications, radiologic fusion rates, pre- and postoperative patient-reported outcome measures (PROMs) scores (visual analogue scale (VAS) for back pain, VAS for leg pain, Japanese Orthopaedic Association, Oswestry Disability Index and MacNab criteria), length of hospital stay, and need for revision surgeries. A learning curve was then developed by a logarithmic curve-fit regression analysis. Results The operative time gradually decreased over time, and an asymptote was reached after about 25 cases. Compared with group B or C, group A had significantly longer operative time, significantly longer length of hospital stay, needed significantly more x-ray exposure time. Though not significantly different, there are fewer complications and revision surgeries over time. There is no significant difference over time in PROMs scores except for the VAS back scores. Conclusions PELIF is an alternative for minimal invasive surgery for LDD, PELIF presents a learning curve to the practicing spine surgeon with regard to operative time, x-ray exposure time, length of hospital stay, clinical PROMs and radiographic outcomes and complications. The presented PELIF learning curve provided valuable insight to surgeons interested in performing this surgery.