[Clinical and radiological evaluation of sliding positioning and slotting with bone rongeur in posterior cervical laminoplasty].

OBJECTIVE

To investigate the clinical value and imaging evaluation of bone rongeur sliding positioning technique in precise laminotomy during posterior cervical spinal canal expansion and reconstruction surgery.

METHODS

A retrospective analysis was conducted on the clinical data of 60 patients with cervical spondylotic myelopathy who underwent cervical posterior single-door laminoplasty with spinal canal expansion surgery for cervical spine treatment from October 2020 to December 2023, including 40 males and 20 females;age ranged from 39 to 78 years with a mean of (60.3±9.1)years;disease duration ranged from 1 to 120 months with a mean of (19.6±32.1) months. Among the 30 cases with concurrent ossification of the posterior longitudinal ligament of the cervical spine, 18 were focal-type, 7 were segmental-type, 2 were continuous-type, and 3 were mixed-type. The preoperative Modified Japanese Orthopaedic Association (mJOA) scores ranged from 7 to 14 wit a mean of (11.0±1.8) scores. MRI T2-weighted imaging revealed high signal intensity changes in the spinal cord in 31 cases; hypertension was present in 20 cases, and diabetes in 6 cases. The surgical decompression segments were as follows:C3-C7 in 31 cases, C3-C6 in 11 cases, C4-C7 in 14 cases, C4-C6 in 2 cases, C3-C5 in 1 case, and C5-C7 in 1 case. During the procedure, the bone rongeur sliding positioning technique was consistently employed for laminotomy. Based on CT data, the distance between the apexes of both pedicles, the width of the bilateral slits at the decompression level postoperatively, the distances from the slitting points to the medial wall of the spinal canal, as well as the transverse diameter of the spinal cord and the interlaminar space at the decompression level were measured. Functional assessment was performed using the mJOA classification system.

RESULTS

CT measurements showed that the distance between bilateral pedicle peaks progressively increased from C3 to C7. In the postoperative decompression segments of C3-C5, the width of bilateral slots was greater than the distance between bilateral pedicle peaks(P<0.001), whereas in the postoperative decompression segments of C6-C7, the width of bilateral slots was smaller than the distance between bilateral pedicle peaks(P<0.05). The distance from the slotted points on both sides to the medial wall of the spinal canal remains relatively constant, ranging from 4.13 to 5.53 mm. MRI measurements indicate that the transverse diameter of the spinal cord was fairly consistent at the C3-C5 segments, whereas it showed a gradual decrease in the C6-C7 segments. In all MRI measurements, the interlaminal distance at the decompression levels of C3-C7 exceeded the spinal cord transverse diameter (P<0.001). All patients were followed up for a duration of 12 to 38 months with an average of (23.0±8.0) months. At the final follow-up, the mJOA score was (17.0±0.9), showing a significant improvement compared to preoperative levels with statistical significance(P<0.001).

CONCLUSION

The posterior cervical laminoplasty with the sliding technique of bone rongeur provides a precise positioning method for slotting the lamina, thereby achieving a good spinal cord decompression effect.