Modified laminoplasty versus laminectomy with fusion in different K-line status among patients with high occupation rate of cervical ossification of longitudinal ligament.

Background Context: For patients with high occupation rate cervical ossification of the posterior longitudinal ligament (HOR-cOPLL) that are K-line negative, laminoplasty often results in poor outcomes due to postoperative loss of cervical curvature. Preserving the posterior muscle-ligament complex (PMLC) on the hinge side during laminoplasty has been shown to reduce cervical curve loss and improve postoperative cervical alignment. We hypothesized that a modified laminoplasty (mLP) with preserving the PMLC could maintain cervical curvature and achieve similar neurological recovery to that of laminectomy with fusion (LF), regardless of K-line status.

Purpose: To compare the clinical and radiological results between mLP and LF among patients with HOR-cOPLL during postoperative 2-year follow-up.

Study Design: Prospective observational study.

Patients Sample: Patients with HOR-cOPLL were enrolled between December 2018 and February 2022. Among them, 30 patients underwent LF, while 34 patients received mLP.

Outcome Measures: The modified Japanese Orthopedic Association (mJOA) score and the mJOA recovery rate (mJOA RR) were used for neurological improvement. The Neck Disability Index (NDI) score, Visual Analog Scale (VAS) scores were for neck and/or shoulder pain. Perioperative values included operative time, estimated blood loss, and perioperative complications. Radiological characteristics consisted of the cervical Cobb angle and cervical range of motion (ROM), etc. METHODS: Independent samples t-test and Mann-Whitney U-test were used to compare normally and nonnormally distributed continuous variables between 2 groups, respectively. Paired sample t-tests and Wilcoxon signed-rank tests were used to evaluate changes in variables before and 2 years after surgery. Subgroup based on K-line was performed to access the differences between 2 groups.

Results: The mLP group experienced shorter surgery times (101 min vs. 122.5 min, p=.009), less blood loss (175 mL vs. 200 mL, p=.020), and had complication rates comparable to those of the LF group. The mLP (12.5 vs. 16.5, p<.001) and LF groups (11.5 vs. 15.25, p<.001) showed significant and comparable improvements in mJOA (p=.648) and mJOA RR (65.16% vs. 68.33%, p=.598) at postoperative 2-year follow-up, which were consistent in both K-line positive and negative subgroups. Postoperative NDI, VAS, and axial symptoms were also comparable between the 2 groups. While maintaining a cervical curve comparable to the LF group (3.17° vs. 2.95°, p=.935), the mLP group exhibited a lesser reduction in ROM at the 2-year mark (17.77° vs. 12.02°, p=.033), although this was not significant in either K-line positive or negative subgroups.

Conclusions: This was the first prospective cohort to compare mLP and LF for HOR-cOPLL. Both the mLP and LF groups demonstrated significant neurological recovery and similar preservation of cervical curvature over a 2-year period, regardless of K-line status. Notably, mLP offers advantages in surgical efficiency and reduced blood loss, suggesting its potential as a less invasive alternative to LF.