Efficacy and Safety of Ultrasonic Bone Curette-assisted Dome-like Laminoplasty in the Treatment of Cervical Ossification of Longitudinal Ligament

Abstract

Objective: To assess the efficacy and safety of ultrasonic bone curette-assisted dome-like laminoplasty in the treatment of ossification of longitudinal ligament (OPLL) involving C₂ .

Methods: A total of 64 patients with OPLL involving C₂ level were enrolled. Thirty-eight patients who underwent ultrasonic bone curette-assisted dome-like laminoplasty were defined as ultrasonic bone curette group (UBC), and 28 patients who underwent traditional high-speed drill-assisted dome-like laminoplasty were defined as high-speed drill group (HSD). Patient characteristics such as age, sex, body mass index (BMI), symptomatic duration, and other information like the type of OPLL, the time of surgery, blood loss, C₂ -C₇ Cobb angle change and complications were all recorded and compared. The Japanese Orthopaedic Association (JOA) score, the nerve root functional improvement rate (IR), and the visual analogue scale (VAS) were used to assess neurological recovery and pain relief. The change of the distance between the apex of ossification and a continuous line connecting the anterior edges of the lamina was measured to assess the spinal expansion extent. The measured data were statistically processed and analyzed using SPSS 21.0 software, and the measurement data were expressed as mean ± SD.

Results: In ultrasonic bone curette (UBC) group and high-speed drill group (HSD) group, the average time for laminoplasty was 52.3 ± 18.2 min and 76.0 ± 21.8 min and the mean bleeding loss volume was 155.5 ± 41.3 mL and 177.4 ± 54.7 mL, respectively, with a statistically significant difference between the groups. Both groups demonstrated a significant improvement in neurological function. However, the VAS score in UBC group was lower than in HSD group at the 6-month follow-up (P < 0.05), but there was no significant difference at 1-year follow-up. We found that the loss of lordosis was 1.5° ± 1.0° in UBC group, which is significantly lower than that of HSD group at 1-year follow-up (3.8° ± 1.2°, P < 0.05). According to the change of canal dimension, we found that the expansion extent of the spinal canal in UBC group was similar to that of HSD group (P > 0.05). Only one patient in the UBC group and five patients in the HSD group displayed cerebrospinal fluid (CSF) leakag.

Conclusions: With the use of ultrasonic bone curette in OPLL dome-like decompression, the decompression surgery could be completed relatively safely and quickly. It effectively reduced the amount of intraoperative blood loss and complications, and had better initial recovery of neck pain.

Keywords: Axis; Dome-like laminectomy; Laminoplasty; OPLL.

Fig 1

Illustration showing the dome resection area in C ₂ using ultrasonic osteotome. (A) The ultrasonic osteotome is applied to achieve the dome‐like resection of C₂ lamina and spinous process (blue dashed line indicates the area to be cut), note that the posterior part of spinous process is preserved mostly to prevent the removal of the attached muscles. (B) The dome‐shape osteotomy starts from the posterior part of the C₂ spinous process to the ventral and lower part of C₂ lamina to expose the posterior part of spinal cord (blue dashed line indicate the area to be cut). (C, D) The illustrations showing the result of C₂ dome‐like laminectomy, the brown dashed line indicates the area been cut.

Fig 2

CT scans showing the area of dissected C₂ lamina. The upper two figures showing the same section before (A) and after (B) of the ultrasonic curette‐assisted laminoplasty in C₂ level. The lower figures showing the reconstructed 3D view of the patient after the curette‐assisted laminoplasty (C, D). Note that resection of flavum ligament is necessary to certify that there has been sufficient space for the spinal cord to shift after the procedure (area is indicated with a white circle in CT reconstructed image in D).

Fig 3

MRI and X‐ray scans showing the shifting of spinal cord after the ultrasonic curette‐assisted laminoplasty. Figure A and C showing the radiograph and MRI sagittal view of the cervical spine before the surgery. B and D showing the radiograph and MRI sagittal view of the cervical spine after the surgery. Note that the spinal cord was loosened in the lower part of C₂ level.