Kazunari Takeuchi

A radiographic study in 111 patients using radiographs was conducted. To clarify whether the modified laminoplasty with C3 laminectomy preserving the semispinalis cervicis (SSC) inserted into C2 could maintain the postopertive range of motion (ROM) and sagittal alignment compared with conventional C3-C7 laminoplasty reattaching the muscle to C2. Intraoperative injury of the SSC is relevant to the significant loss of ROM and the malalignment after laminoplasty. To expose the C3 lamina, however, the SSC inserted into C2 could not be preserved in conventional C3-C7 laminoplasty. The ROM and sagittal alignment of 70 patients (group A) (52 men, 18 women, mean age 59 y, mean follow-up period 1 y and 7 mo) with C4-C7 laminoplasty with C3 laminectomy were compared with those of 41 patients (group B) (28 men, 13 women, mean age 59 y, mean follow-up period 2 y and 6 mo) with C3-C7 laminoplasty using radiographs of the cervical spine. Regarding C2-C7 ROM, the postoperative ROM was larger (P=0.003) and the decrease rate of ROM was smaller (P=0.0006), and decreased ROM in extension was smaller (P<0.0001) in group A. Regarding O-C2 ROM, the increased ROM was smaller (P=0.043) and increased ROM in extension was smaller (P=0.001) in group A. Regarding O-C7 ROM, the postoperative ROM was larger (P=0.029) in group A. Regarding the cervical alignment, the increased lordotic angle at O-C2 was smaller (P=0.046) in group A. This modified laminoplasty preserving the SSC inserted into C2 is an effective procedure for maintaining postoperative ROM, especially in extension, and sagittal alignment of the upper cervical spine well.

Although difficulties with neck mobility often interfere with patients’ activities of daily living (ADL) after cervical laminoplasty, there was no detailed study on the relation between the limitations of ADL accompanying postoperative reduced neck mobility and the cervical posterior approach. The aim of this study was to compare retrospectively the frequency of limitations of ADL accompanying neck mobility after laminoplasty preserving the semispinalis cervicis inserted into the C2 spinous process with that after laminoplasty reattaching the muscle to C2. Forty-nine patients after C4–C7 laminoplasty with C3 laminectomy preserving the semispinalis cervicis inserted into C2 (Group A) and 24 patients after C3–C7 laminoplasty reattaching the muscle (Group B) were evaluated. The frequency of postoperative limitations of ADL accompanying each of three neck movements of extension, flexion and rotation were investigated. The postoperative O–C7 angles at extension and flexion was measured on lateral extension and flexion radiographs of the cervical spine, respectively. The postoperative cervical range of motion in rotation was measured in the cranial view using a digital camera. Frequency of limitations of ADL accompanying extension was lower (P = 0.037) in Group A (2%) than in Group B (17%). Frequency of limitations of ADL accompanying flexion was similar in Group A (8%) and Group B (4%). Frequency of limitations of ADL accompanying rotation was lower (P = 0.031) in Group A (12%) than in Group B (33%). Average O–C7 angle at extension was significantly larger (P = 0.002) in Group A (147°) than in Group B (136°). Average O–C7 angle at flexion was similar in Group A (93°) and Group B (91°). Average range of motion in rotation was significantly larger (P = 0.004) in Group A (110°) than in Group B (91°). This retrospective study suggested that the frequency of limitations of ADL accompanying neck extension or rotation was lower after laminoplasty preserving the semispinalis cervicis inserted into C2 than after laminoplasty reattaching the muscle.

After laminoplasty, difficulties with neck mobility often interfere with patients’ activities of daily living (ADL). Although it has been reported that the flexion–extension range of motion significantly decreased after laminoplasty, in many studies using radiographs there were few patient-based outcomes. The purpose of this study was to reveal the frequency, severity and factors related to limitations of ADL accompanying neck mobility after laminoplasty. A total of 58 patients were evaluated after laminoplasty to determine the frequency, severity and pre- and postoperative related factors of postoperative limitations of ADL accompanying each of three neck movements: (1) extension, (2) flexion and (3) rotation. The severity of limitations of each ADL was assessed using a questionnaire that was completed by the patient. Difficulties in neck movement, such as rotation (41%), extension (34%) and flexion (17%), in that order (P = 0.001), caused limitations of ADL. The most relevant factor of limitations of ADL accompanying extension, flexion, and rotation were small postoperative O–C7 range of motion (P = 0.0001), small preoperative O–C7 range of motion (P = 0.001), and small postoperative rotation range of motion (P = 0.0005), respectively. There were more than a few patients with limitations of ADL accompanying reduced neck mobility after laminoplasty. This knowledge may be useful in the clinical outcomes of cervical laminoplasty.

C3-C7 laminoplasty has been the standard treatment for cervical myelopathy, although several recent reports described C3-C6 laminoplasty for preserving the muscles inserting in C7 and reducing postoperative axial symptoms. However, postoperative changes at C6/C7 of the lower end of C3-C6 laminoplasty, especially regarding a possibility of postoperative spinal canal narrowing have not been measured. The purpose of this study was to clarify postoperative changes at the lower end of laminoplasty. Pre and postoperative spinal dura diameter at the lower end of conventional C3-C7 laminoplasty using MRI, and the related factors for spinal dura diameter and the causes of postoperative dura narrowing were investigated. At the last follow-up after C3-C7 laminoplasty, dura diameter at C7/T1 was significantly wider after operation than before operation, and postoperative narrowing of dura diameter, which was found in 20% of patients, was a maximum amount of one millimeter. No pre and postoperative factor significantly correlated with dura diameter at C7/T1. The causes of postoperative narrowing at the lower end of laminoplasty were disc protrusion and/or posterior scar, or segmental angulation of the spinal cord. In conclusion, the presence of preoperative subarachnoid space over one millimeter at C6/C7 may be able to be one of the radiological indications for C3-C6 laminoplasty.

Results of C4–C7 laminoplasty with C3 laminectomy and C3–C7 laminoplasty were compared. To clarify prospectively whether the modified laminoplasty preserving the semispinalis cervicis inserted into C2 could reduce the axial symptoms compared with conventional laminoplasty reattaching the muscle to C2. Intraoperative damage of the semispinalis cervicis is relevant to the development of axial symptoms after laminoplasty. In C3–C7 laminoplasty, however, it is difficult to preserve the muscle insertion into C2 while opening the C3 lamina. The axial symptoms of 40 patients (Group A) with C4–C7 laminoplasty with C3 laminectomy were compared with those of 16 patients (Group B) with C3–C7 laminoplasty. The cross-sectional areas of the cervical posterior muscles were measured on magnetic resonance images. The number of patients with no postoperative axial symptoms increased (P = 0.035) from 19% to 52.5%, and the number of patients whose symptoms worsened after surgery decreased (P = 0.020) from 50% to 17.5%. The average atrophy rate of cross-sectional area was smaller (P < 0.001) in Group A (2.4%) than in Group B (10.8%). This method was less invasive to the cervical posterior muscles than C3–C7 laminoplasty. This is an effective procedure for preventing postoperative axial symptoms.

Some patients who had cervical laminoplasty with subsequent substantial loss of cervical lordosis have shown failed healing of a repaired semispinalis cervicis. We also have identified some patients in whom it is difficult to repair the C2 spinous process during laminoplasty. We therefore quantitatively analyzed the morphologic features of the C2 insertion of the semispinalis cervicis and obtained data relevant to the repair of the muscle. In 24 cadavers, the width and height of the semispinalis cervicis insertion in C2 and the length and opening angle of the C2 spinous process were measured. We observed considerable individual variations in the morphologic features of the C2 spinous process and the C2 insertion of the semispinalis cervicis. The opening angle of the C2 spinous process was smaller in males than in females. In most of the cases, the width of the insertion was narrower than the width of the spinous process spacers that commonly are used in laminoplasty. Preoperative prediction of the morphologic features of insertion at the original site is possible by measuring the opening angle of the C2 spinous process using three-dimensional computed tomography because the muscle insertion correlated with the angle of the C2 spinous process. This information may be useful in reattaching the semispinalis cervicis during cervical laminoplasty.

Introduction: Some authors pointed out that there were more than a few patients with inadvertent C2–C3 union after C1–C2 posterior fusion, although few detailed studies of C2–C3 union have been reported. The purpose of this study was to clarify whether C2–C3 union accelerated adjacent C3–C4 disc degeneration after C1–C2 posterior fusion and to investigate the related factors for C2–C3 union. Methods: Sixteen patients with rheumatoid arthritis (RA group) (4 males, 12 females, mean age 60 years, mean follow-up period 4 years and 3 months) and fifteen patients without RA (non-RA group) (11 males, 4 females, mean 52 years, mean follow-up period 3 years and 10 months) who underwent C1–C2 posterior fusion were radiologically assessed. The C2–C3 union was defined as trabecular bone formation at C2–C3 interlamina in lateral radiograph. C3–C4 disc height was measured to evaluate the disc degeneration. Results: C2–C3 union rate was 56% and 60% in RA group and non-RA group, respectively. In RA group, postoperative C3–C4 disc height was lower (Student’s t-test, P = 0.029) and the decrease rate of C3–C4 disc height was higher (Student’s t-test, P = 0.015) in patients with C2–C3 union than in patients without C2–C3 union. In non-RA group, the age at operation was older (Student’s t-test, P = 0.0007), and the C1–C2 fusion angle (Student’s t-test, P = 0.012) was smaller in patients with C2–C3 union than in patients without C2–C3 union. Conclusions: C2–C3 union after C1–C2 posterior fusion occurred in more than half of both groups. Inadvertent C2–C3 union should be considered a radiological complication and a potential risk factor due to acceleration of C3–C4 disc degeneration in RA.