103. Evaluation of the efficacy and safety of 3D-printing porous titanium cage with non-window vs window type in posterior lumbar interbody fusion: a prospective, randomized, multicenter study

BACKGROUND CONTEXT Degenerative disc disease (DDD) is a common cause of low back pain that frequently involves more than one level of the lumbar spine. Anterior lumbar interbody fusion with posterior pedicle screw fixation (ALIF PPF) or transforaminal lumbar interbody fusion with posterior spinal instrumentation (TLIF PSI) can be used to achieve sufficient bony fusion as well as address the injury when conservative measures fail. The benefits of fusion for pain relief and clinical outcomes improvement have been well outlined in the literature; however, long-term consequences between varying approaches remain controversial. PURPOSE The study compares the outcomes of ALIF PPF vs TLIF PSI in 2-level lumbar fusion for the treatment of spondylosis secondary to DDD. STUDY DESIGN/SETTING Matched retrospective cohort study. PATIENT SAMPLE A total of 80 patients: 40 ALIF PPF and 40 TLIF PSI. OUTCOME MEASURES 1) Long-term revision rate and average time to revision, 2) complication rate, 3) pelvic incidence- lumbar lordosis (PI-LL) mismatch correction 4) Functional outcome scores: Oswestry Disability Index (ODI), as well as visual analog scale for back (VAS-b) and leg (VAS-l) pain. METHODS All patients from 2013 to 2018 with at least 2 years of follow-up who underwent 2-level ALIF PPF or TLIF PSI for the treatment of spondylosis secondary to DDD were identified by retrospective review. Cohorts were matched for age, sex, BMI, and levels operated. Researchers compared revision rates, average time to revision and complications between groups. PI-LL mismatch was calculated from both pre- and postoperative radiographs and degree of correction was compared. Functional outcomes were assessed with ODI, VAS-b and VAS-l measurements at follow-up visits. Standard binomial and categorical comparative analyses were performed. RESULTS Mean follow-up of the ALIF PPF and TLIF PSI groups were 39.5 and 45.6 months, respectively. The overall revision rates (ALIF: 10.0% vs TLIF: 5.0%, p= 0.396) and mean time to revision (ALIF: 323.1 ± 200.2 days vs 244.2 ± 178.9 days, p= 0.067) were not significantly different between the groups. In the ALIF PPF group, there were 8 smokers, two of whom had revision surgery; the TLIF PSI group had 10 smokers, one of whom had revision surgery. Two patients in the ALIF PPF group sustained injury to the common iliac vein intraoperatively. ALIF PPF and TLIF PSI cohorts achieved a similar proportion of PI-LL mismatch correction (ALIF: 81.3% vs TLIF: 87.5%, p= 0.644). Each cohort had 13 females and 27 males. Cohorts were matched for age, BMI, sex, and levels operated. Both groups experienced significant improvements in their functional outcome scores compared to their preoperative values (p<0.001), but no significant differences were found in the degree of improvement between groups at any point in time. CONCLUSIONS Our 2-year results suggest that ALIF PPF and TLIF PSI are both reasonable alternatives for the treatment of symptomatic, 2-level DDD. At final follow-up, there were fewer revision surgeries in the TLIF PSI cohort; however, the difference was not significant. Both cohorts achieved a similar proportion of PI-LL mismatch correction and improvement in functional outcome scores. FDA Device/Drug Status This abstract does not discuss or include any applicable devices or drugs. Degenerative disc disease (DDD) is a common cause of low back pain that frequently involves more than one level of the lumbar spine. Anterior lumbar interbody fusion with posterior pedicle screw fixation (ALIF PPF) or transforaminal lumbar interbody fusion with posterior spinal instrumentation (TLIF PSI) can be used to achieve sufficient bony fusion as well as address the injury when conservative measures fail. The benefits of fusion for pain relief and clinical outcomes improvement have been well outlined in the literature; however, long-term consequences between varying approaches remain controversial. The study compares the outcomes of ALIF PPF vs TLIF PSI in 2-level lumbar fusion for the treatment of spondylosis secondary to DDD. Matched retrospective cohort study. A total of 80 patients: 40 ALIF PPF and 40 TLIF PSI. 1) Long-term revision rate and average time to revision, 2) complication rate, 3) pelvic incidence- lumbar lordosis (PI-LL) mismatch correction 4) Functional outcome scores: Oswestry Disability Index (ODI), as well as visual analog scale for back (VAS-b) and leg (VAS-l) pain. All patients from 2013 to 2018 with at least 2 years of follow-up who underwent 2-level ALIF PPF or TLIF PSI for the treatment of spondylosis secondary to DDD were identified by retrospective review. Cohorts were matched for age, sex, BMI, and levels operated. Researchers compared revision rates, average time to revision and complications between groups. PI-LL mismatch was calculated from both pre- and postoperative radiographs and degree of correction was compared. Functional outcomes were assessed with ODI, VAS-b and VAS-l measurements at follow-up visits. Standard binomial and categorical comparative analyses were performed. Mean follow-up of the ALIF PPF and TLIF PSI groups were 39.5 and 45.6 months, respectively. The overall revision rates (ALIF: 10.0% vs TLIF: 5.0%, p= 0.396) and mean time to revision (ALIF: 323.1 ± 200.2 days vs 244.2 ± 178.9 days, p= 0.067) were not significantly different between the groups. In the ALIF PPF group, there were 8 smokers, two of whom had revision surgery; the TLIF PSI group had 10 smokers, one of whom had revision surgery. Two patients in the ALIF PPF group sustained injury to the common iliac vein intraoperatively. ALIF PPF and TLIF PSI cohorts achieved a similar proportion of PI-LL mismatch correction (ALIF: 81.3% vs TLIF: 87.5%, p= 0.644). Each cohort had 13 females and 27 males. Cohorts were matched for age, BMI, sex, and levels operated. Both groups experienced significant improvements in their functional outcome scores compared to their preoperative values (p<0.001), but no significant differences were found in the degree of improvement between groups at any point in time. Our 2-year results suggest that ALIF PPF and TLIF PSI are both reasonable alternatives for the treatment of symptomatic, 2-level DDD. At final follow-up, there were fewer revision surgeries in the TLIF PSI cohort; however, the difference was not significant. Both cohorts achieved a similar proportion of PI-LL mismatch correction and improvement in functional outcome scores.