[Vertebral three-dimensional motion characteristics of adjacent segments in patients with isthmic spondylolisthesis in vivo]

Segmental vertebral three-dimensional motion in patients with L4 isthmic spondylolisthesis under weight-bearing conditions

OBJECTIVE

To investigate in vivo 6-degree-of-freedom (DOF) vertebral motion in patients with isthmic spondylolisthesis (IS) during various functional weight-bearing activities.

METHODS

Fifteen asymptomatic volunteers (mean age 54.8 years) and fourteen patients with IS at L4-5 (mean age 53.4 years) were recruited. The positions of the vertebrae (L4-L5) in the supine, standing, flexion-extension, left-right twisting and left-right bending positions were determined using previously described CT-based models and dual fluoroscopic imaging techniques. Local coordinate systems were established at the center of the anterior vertebra of L4 isthmic spondylolisthesis (AIS), the posterior lamina of L4 isthmic spondylolisthesis (PIS) and the center of the L5 vertebra to obtain the 6DOF range of motion (ROM) at L4-L5 and the range of motion (ROM) between the AIS and the PIS.

RESULTS

The translation along the anteroposterior axis at L4-L5 during flexion-extension, left-right bending and left-right twisting was significantly greater than that of the healthy participants. However, the translation along the mediolateral axis at L4-L5 presented paradoxical motion under different positions: the ROM increased in the supine-standing and flexion-extension positions but decreased in the left-right bending and left-right twisting positions. The separation along the anteroposterior axis during flexion was significantly greater than that during standing, on average, reaching more than 1 mm. The separation along the mediolateral axis during standing, flexion and extension was significantly greater than that in the supine position.

CONCLUSIONS

This study revealed the occurrence of displacement between the AIS and PIS, primarily in the form of separation during flexion. Symptomatic patients with isthmic spondylolisthesis exhibit intervertebral instability, which might be underestimated by flexion-extension radiographs.

Dynamic segmental kinematics of the lumbar spine during diagnostic movements

Background: In vivo measurements of segmental-level kinematics are a promising avenue for better understanding the relationship between pain and its underlying, multi-factorial basis. To date, the bulk of the reported segmental-level motion has been restricted to single plane motions. Methods: The present work implemented a novel marker set used with an optical motion capture system to non-invasively measure dynamic, 3D in vivo segmental kinematics of the lower spine in a laboratory setting. Lumbar spinal kinematics were measured for 28 subjects during 17 diagnostic movements. Results: Overall regional range of motion data and lumbar angular velocity measurement were consistent with previously published studies. Key findings from the work included measurement of differences in ascending versus descending segmental velocities during functional movements and observations of motion coupling paradigms in the lumbar spinal segments. Conclusion: The work contributes to the task of establishing a baseline of segmental lumbar movement patterns in an asymptomatic cohort, which serves as a necessary pre-requisite for identifying pathological and symptomatic deviations from the baseline.

[Comparison of the effectiveness of vertebral arch replantation and laminectomy in the treatment of mild to moderate isthmic spondylolisthesis]

OBJECTIVE

To compare the effectiveness of vertebral arch replantation and laminectomy in the treatment of mild to moderate isthmic spondylolisthesis.

METHODS

The clinical data of 66 patients with isthmic spondylolisthesis treated with vertebral arch replantation or laminectomy between March 2014 and July 2016 were retrospectively analyzed. They were divided into trial group (34 cases, treated with complete replantation of vertebral arch, intervertebral fusion, and internal fixation) and control group (32 cases, treated with laminectomy with intervertebral fusion and internal fixation) according to different surgical methods. There was no significant difference in general data of gender, age, disease duration, lesion segment, Meyerding grade, and preoperative visual analogue scale (VAS) score, Oswestry disability index (ODI) score, Japanese Orthopaedic Association (JOA) score between the two groups ( P>0.05). The operation time, intraoperative blood loss, complications, vertebral arch fusion of trial group, and epidural scar formation of the two groups were recorded. The VAS score, JOA score, and ODI score were evaluated at preoperation, 3, 6, 12 months after operation, and at last follow-up. The effectiveness was evaluated according to HOU Shuxun's criteria.

RESULTS

All the patients successfully completed the surgery, without any aggravation of nerve injury, dural tear, infection, etc. There was no significant difference in the operation time between the two groups ( t=0.583, P=0.562), but the intraoperative blood loss was significantly lower in the trial group than that in the control group ( t=2.134, P=0.037). All the 66 patients were followed up 13-18 months (mean, 16.2 months). Postoperative clinical symptoms of all patients were significantly improved. In the control group, 7 cases were found to have symptoms of spinal canal stenosis with postoperative posture changes at 3 months after operation, and 5 cases showed mild lower limb numbness at 18 months after operation. No complication such as infection and nerve injury occurred in other patients. In the trial group, 34 cases of epidural scar tissue were completely blocked outside the replantation vertebral arch, while in the control group, 11 cases of epidural scar tissue invaded the spinal canal. At last follow-up, the fusion rate of intervertebral bone grafting and vertebral arch replantation in the trial group was 100%, and the fusion rate of intervertebral bone grafting in the control group was also 100%. The VAS score, ODI score, and JOA score were significantly improved at each time point after operation ( P<0.01). The ODI score and JOA score of the trial group were significantly better than those of the control group at 3 months after operation and at last follow-up ( P<0.05), and there was no significant difference in scores between the two groups at other time points ( P>0.05). According to HOU Shuxun's criteria, the excellent and good rate was 91.2% in the trial group and 84.4% in the control group, showing no significant difference ( χ 2=1.092, P=0.573).

CONCLUSION

Compared with laminectomy, vertebral arch replantation can better improve postoperative neurological symptoms, maximize the reconstruction of the bone spinal canal, restore the stability of the intraspinal environment, and it is a better surgical method for lumbar isthmic spondylolisthesis.