Low-Profile Posterior Lumbar Fusion Combined With Proximal Interlaminar Coflex Dynamic Fixation for Lumbar...

Lumbar fusion combined with topping-off dynamic stabilization has been used to reduce adjacent-segment stress in lumbar degenerative diseases. However, traditional pedicle screw-based topping-off surgery may require relatively extensive posterior exposure, which can increase soft-tissue injury and delay postoperative recovery. This study aimed to evaluate the feasibility and effectiveness of low-profile lumbar fusion using cortical bone trajectory screws (CBTs) and pedicle screw (PS) internal fixation combined with Coflex dynamic stabilization, compared to traditional PS-based topping-off.

A retrospective cohort study was conducted using data from patients with lumbar degenerative diseases treated between December 2021 and January 2023. Patients who underwent either the low-profile topping-off procedure or traditional topping-off surgery were enrolled. Demographic data, perioperative parameters, radiographic outcomes, complications, and clinical outcomes were collected and compared between the two groups. Statistical analyses included Student's t-test, chi-square test, two-way analysis of variance, multivariable linear regression, and binary logistic regression.

A total of 229 patients undergoing single-level L4/L5 fusion (104 in the low-profile group and 125 in the traditional group) were followed for 35.69 ± 4.76 months (range, 24-40 months). Baseline characteristics, including age, sex, bone mineral density (BMD), diagnosis distribution, and follow-up duration, were comparable between groups (p > 0.05). Compared with the traditional group, the low-profile group demonstrated improved perioperative outcomes, with less intraoperative blood loss, shorter incision length, lower drainage volume, and shorter postoperative hospital stay, while operative time was similar. Radiographically, the low-profile group showed a higher fusion success rate at final follow-up (Bridwell Grade I + II: 91.3% vs. 80.8%). Adjacent-segment analyses indicated better preservation of cranial adjacent-segment radiographic parameters (L3/4) at 24 months in the low-profile group, whereas the overall adjacent segment degeneration (ASD) incidence did not differ significantly between groups. Both groups achieved significant improvements in Visual Analog Scale (VAS), Oswestry Disability Index (ODI), and Japanese Orthopedic Association Score (JOA); although postoperative back pain VAS and ODI were statistically lower in the low-profile group, leg pain VAS, JOA, and overall complication rates were comparable. Multivariable regression adjusting for age, sex, BMD, diagnosis type, and baseline ODI showed that surgical approach remained independently associated with final ODI, while no significant association with overall complications was observed.

Low-profile topping-off surgery is as effective as traditional topping-off for lumbar degenerative diseases, which has the strength of being less invasive and enabling more rapid recovery.