Learning curve of a complex surgical technique: minimally invasive transforaminal lumbar interbody fusion (MIS TLIF).

STUDY DESIGN: Prospective cohort study.

OBJECTIVE: This study aimed to evaluate the learning curve of minimally invasive transforaminal lumbar interbody fusion (MIS TLIF).

SUMMARY OF BACKGROUND DATA: Very few studies have evaluated the learning curve of this technically demanding surgery. We intend to evaluate the learning curve of MIS TLIF with a larger sample size and assess surgical competence based not only on operative time but with perioperative variables, clinical and radiologic outcomes, incidence of complications, and patient satisfaction.

MATERIALS AND METHODS: From 2005 to 2009, the first 90 single-level MIS TLIF, which utilized a consistent technique and spinal instrumentation, performed by a single surgeon at our tertiary institution were studied. Variables studied included operative time, perioperative variables, clinical (Visual Analogue Scores for back and leg pain, Oswestry Disability Index, North American Spine Society Scores for neurogenic symptoms) and radiologic outcomes, incidence of complications and patient rating of expectation met, and the overall result of surgery.

RESULTS: The asymptote of the surgeon's learning curve for MIS TLIF was achieved at the 44th case. Comparing the early group of 44 patients to the latter 46, the demographics were similar. For operative parameters, only 3 variables showed differences between the 2 groups: mean operative duration, fluoroscopy duration, and usage of patient-controlled analgesia. At the final follow-up, for clinical outcome parameters, the 2 groups were different in 3 parameters: VAS scores for back, leg pain, and neurogenic symptom scores. For radiologic outcome, both groups showed similar good fusion rates. For complications, none of the MIS TLIF cases were converted to open TLIF intraoperatively. In the early group, there were 3 complications: 1 incidental durotomy and 2 asymptomatic cage migrations; and in the latter group, there was 1 asymptomatic cage migration.

CONCLUSIONS: In our study, technical proficiency in MIS TLIF was achieved after 44 surgeries, and the latter patients benefited from shorter operative duration and radiation, less pain, and more relief in their back, leg, and neurogenic symptoms.