Objective:

This case-series aims to characterize the Lateral Lumbar Interbody Fusion (LLIF) surgical learning curve and investigate changes in perioperative/postoperative clinical parameters associated with increased operative experience.

Methods:

Surgical learning curve was defined using 3-parameter asymptotic regression and piecewise linear regression, yielding a “learning phase” cohort (patients 1-53) and a “proficient phase” cohort (patients 54-179). Utilizing a 5-point grading scale, ipsilateral iliopsoas (hip-flexion) and quadriceps (knee-extension) muscle strength and thigh/groin sensory disturbances were compared for differences pre/postoperatively with chi-squared. Patient-reported outcome measures (PROMs) were collected pre/post-operatively and compared between cohorts with unpaired t-test.

Results:

Proficient phase cohort demonstrated significantly reduced operative time, estimated blood loss, postoperative length of stay, and narcotic consumption on POD 0/1. Proficient phase cohort displayed decreased disability at 6-weeks/6-months. Proficient phase cohort demonstrated significant improvement at all timepoints for disability/pain/physical function, except 6-weeks/2-years for physical function, whereas learning phase cohort demonstrated improvement in disability beginning at 6-months, leg pain at all timepoints, and back pain through 6-months. Ipsilateral groin/thigh sensory disturbances and iliopsoas/quadriceps weakness improved with increasing operative experience.

Conclusion:

Proficient surgical learning cohort demonstrated significantly improved perioperative profile, reduced complication rate, and reduced rates of iliopsoas+quadriceps weakness. While patients in the proficient phase cohort demonstrated earlier improvement in disability/physical function scores when compared to the learning phase, 2-year outcome measures did not differ. Long-term clinical outcomes suggest that patient safety and quality of life is not compromised during learning phase, but patients may be particularly susceptible to femoral nerve injury early in a surgeon’s practice.