[Clinical study on the treatment of postoperative recurrence of lumbar disc herniation with intervertebral fusion]

OBJECTIVE

To explore clinical effect of different intervertebral fusion devices (cage) in treating postoperative recurrent lumbar disc herniation (LDH).

METHODS

One hundred and forty-two LDH patients with recurrence after simple intervertebral disc nucleus pulpoideectomy from January 2019 to January 2021 were retrospectively analyzed. All patients were treated with combined underchannel fixation and interbody fusion and divided into a single anatomical group,two-anatomical group and a single banana group according to types and numbers of implanted cage. There were 51 patients in a single anatomical group,included 29 males and 22 females,aged from 39 to 65 years old with an average of (53.74±5.68) years old;body mass index (BMI) ranged from 18.62 to 28.13 kg·m-2 with an average of (22.08±2.15) kg·m-2;the interval between operation and recurrence ranged from 0.5 to 4.0 years with an average of (2.7±0.8) years;5 patients with L3,4,35 patients with L4,5 and 11 patients with L5S1;a single anatomical cage was implanted. There were 46 patients in two-anatomical group,included 25 males and 21 females,aged from 37 to 66 years old with an average of (54.52±6.02) years old;BMI ranged from 18.25 to 28.44 kg·m-2 with an average of (21.74±1.83) kg·m-2;the interval between operation and recurrence ranged from 0.5 to 5.0 years with an average of (2.7±0.9) years;4 patients with L3,4,32 patients with L4,5 and 10 patients with L5S1;two-anatomical cages were implanted. There were 45 patients in a single banana group,included 22 males and 23 females,aged from 38 to 65 years old with an average of (54.49±6.45) years old;BMI ranged from 18.85 to 28.20 kg·m-2 with an average of (21.63±1.59) kg·m-2;the interval between operation and recurrence ranged from 0.5 to 5.0 years with an average of (2.6±1.0) years;3 patients with L3,4,36 patients with L4,5 and 16 patients with L5S1;a single banana cage was implanted. Operation time,intraoperative blood loss,incision length,postoperative incision drainage volume,hospital stay and complications among 3 groups were observed and compared. The height of intervertebral space before and after operation,curvature of lordosis and the postoperative intervertebral fusion were compared. Visual analogue scale (VAS) and Oswestry disability index (ODI) were used to evaluate degree of lumbar pain and lumbar function before operation,1 and 6 months after operation,respectively.

RESULTS

All patients among 3 groups were followed up at least 6 months,and no cases were fell out. There were no significant difference in operation time,intraoperative blood loss,incision length,postoperative incision drainage volume and hospital stay among 3 groups (P>0.05). At 6 months after operation,the height of intervertebral space in two-anatomical group and a single group were [(11.08±1.78) mm,(10.95±1.62) mm],curvature of lordosis were [(12.05±1.86) °,(11.63±1.57) °],which were higher than those in a single dissection group (10.14±1.54) mm,(10.92±1.45) °,and the difference were statistically significant (P<0.05). The interbody fusion rate between two-anatomical and a banana group (95.65%,95.56%) were higher than that in a single anatomical group (78.43%) at 6 months after operation (P<0.05). VAS and ODI of lumbar among 3 groups were decreased at 1 and 6 months after operation (P<0.05). There was no significant difference in complications among 3 groups (P>0.05).

CONCLUSION

The three fusion devices could achieve significant results in treating postoperative recurrence of LDH,but the implantation of two-anatomical cage and a single banana cage are more helpful to maintain the height of intervertebral space and lordosis curvature of patients with postoperative recurrence of LDH,and obtain good intervertebral fusion results.

[Herniation of intervertebral disc into thoracolumbar fracture vertebral body leads to malunion of fracture and decrease of intervertebral space height]

OBJECTIVE

To analyze the clinical characteristics of intervertebral disc tissue injury and herniation into the vertebral body in thoracolumbar fracture on fracture healing, vertebral bone defect volume and intervertebral space height.

METHODS

From April 2016 to April 2020, a total of 140 patients with thoracolumbar single vertebral fracture combined with upper intervertebral disc injury treated with pedicle screw rod system reduction and internal fixation in our hospital. There were 83 males and 57 females, aged from 19 to 58 years old, with an average age of (39.33±10.26) years old. All patients were followed up regularly 6 months, 12 months and 18 months after surgery. The patients with injured intervertebral disc tissue not herniated into the fractured vertebral body were the control group, and the patients with injured intervertebral disc and herniated into the fractured vertebral body were the observation group. By detecting the thoracolumbar AP and lateral X-ray films, CT and MRI of the thoracolumbar segment at different follow-up time, calculate the changes of the wedge angle of the fractured vertebral body, the sagittal kyphosis angle and the height of the superior adjacent intervertebral space, the changes of the fracture healing and bone defect volume after the reduction of the vertebral body, and the changes of the intervertebral disc degeneration grade. The prognosis was evaluated by visual analogue scale(VAS) and Oswestry disability index(ODI). Finally, the differences of the above results among different groups were comprehensively analyzed.

RESULTS

All the patients had normal wound healing without complications. A total of 87 patients received complete follow-up data, at least 18 months after internal fixation. Thoracolumbar AP and lateral X-ray films showed that 18 months after the reduction and internal fixation operation, the vertebral wedge angle, sagittal kyphosis angle and the height of the upper adjacent intervertebral space in the observation group were greater than those in the control group(P<0.05). CT scanning showed that the deformity of the fracture healed 12 months after the vertebral body reduction in the observation group and formed a "cavity" of bone defect connected with the intervertebral space, and its volume was significantly increased compared with that before (P<0.05). MRI scanning showed that the degeneration rate of injured intervertebral discs in the observation group was more serious than that in the control group 12 months after operation(P<0.05). However, there was no significant difference in VAS and ODI score at each time.

CONCLUSION

Herniation of injured intervertebral disc tissue hernias into the fractured vertebral body leads to increased bone resorption defect volume around the fracture and forms a malunion "cavity" connected with the intervertebral space. This may be the main reason for the change of vertebral wedge angle, the increase of sagittal kyphosis angle and the decrease of intervertebral space height after removal of internal fixation devices.

[Current understanding of intervertebral space height in anterior cervical fusion]

Anterior cervical fusion surgery is the first choice for spine surgeons in the treatment of cervical spine diseases. It has significant effects in treating cervical degenerative diseases, trauma and tumors and other cervical diseases. In anterior cervical fusion, it is necessary to use a distractor to properly distract the intervertebral space, so as to fully expose and relieve the compressive factors, restore the physiological height, curvature and stability of the lesion segment, and achieve the best surgical effect. However, there is currently no consensus on the standard distraction height for the intervertebral space during anterior cervical surgery. This article reviewsed the progress of intervertebral space height in anterior cervical fusion from three dimensions:the relationship between intervertebral space height and cervical disc degeneration mechanism, the selection of intervertebral space height during operation, the recovery of intervertebral space height and the postoperative effect, so as to provide theoretical basis and reference for spinal surgeons when performing intervertebral distraction during operation.

Effect of Changes in Postoperative Intervertebral Space Height on Clinical and Radiological Outcomes After Cervical Disc Replacement

BACKGROUND

Narrowing of intervertebral space height (ISH) is an important pathological change in degenerative spinal disease, and ideal intraoperative distraction and postoperative intervertebral space maintenance is one of the most expectant goals pursued by spinal surgeons. The effect of postoperative ISH changing on the clinical and radiological outcomes after cervical disc replacement is not fully understood, however.

METHODS

In this study, the height variation and general trend of postoperative ISH in all patients were analyzed. The patients were divided into 3 groups based on the change of postoperative intervertebral space height (ISH)-group A (ISH <2 mm), group B (ISH 2-4 mm), and group C (ISH >4mm)-and the clinical and radiographic results compared among the 3 groups.

RESULTS

A total of 120 consecutive patients with symptomatic cervical disc disease were included in this study. The results showed that the mean ISH increased significantly from 0.729 mm before surgery to 1.143 mm at 1 week, then gradually decreased to 1.032 mm at 3 months, 0.980 mm at 6 months, 0.760 mm at one year, and 0.750 mm at the final follow-up. The average postoperative Neck Disability Index (NDI) was 19.73 ± 0.81, 13.74 ± 4.94, 17.19 ± 4.22, respectively, in the 3 groups at 1 year after surgery and the average range of motion (ROM) was 5.44° ± 3.85° in group A, 9.34° ± 4.38° in group B, and 6.51° ± 4.38° in group C. The mean diameter of the intervertebral foramen was 6.54 ± 1.86 mm in group A, 9.63 ± 2.38 mm in group B, and 9.31 ± 1.68 mm in group C. Degeneration at the superiorly adjacent disc level was observed in 13.51% patients in group A, 9.37% in group B, and 21.05% in group C. Degeneration at the inferiorly adjacent level was radiographically identified in 21.62% in group A, 14.06% in group B, and 26.32% in group C.

CONCLUSIONS

This study revealed that cervical disc replacement cannot maintain the intervertebral disc height obtained immediately after surgery. There is no obvious correlation between the change in intervertebral space height and clinical efficacy in the early postoperative stage. Nonetheless, the intervertebral disc height may affect the NDI index 1 year after surgery. If the postoperative intervertebral space height change can be maintained at 2-4 mm at 1 year, satisfactory ROM, intervertebral foramen diameter, and relatively low adjacent segment degeneration may be obtained after cervical disc replacement.

The segment-dependent changes in lumbar intervertebral space height during flexion-extension motion

Objectives

Many studies have investigated the kinematics of the lumbar spine and the morphological features of the lumbar discs. However, the segment-dependent immediate changes of the lumbar intervertebral space height during flexion-extension motion are still unclear. This study examined the changes of intervertebral space height during flexion-extension motion of lumbar specimens.

Methods

First, we validated the accuracy and repeatability of a custom-made mechanical loading equipment set-up. Eight lumbar specimens underwent CT scanning in flexion, neural, and extension positions by using the equipment set-up. The changes in the disc height and distance between adjacent two pedicle screw entry points (DASEP) of the posterior approach at different lumbar levels (L3/4, L4/5 and L5/S1) were examined on three-dimensional lumbar models, which were reconstructed from the CT images.

Results

All the vertebral motion segments (L3/4, L4/5 and L5/S1) had greater changes in disc height and DASEP from neutral to flexion than from neutral to extension. The change in anterior disc height gradually increased from upper to lower levels, from neutral to flexion. The changes in anterior and posterior disc heights were similar at the L4/5 level from neutral to extension, but the changes in anterior disc height were significantly greater than those in posterior disc height at the L3/4 and L5/S1 levels, from neutral to extension.

Conclusions

The lumbar motion segment showed level-specific changes in disc height and DASEP. The data may be helpful in understanding the physiologic dynamic characteristics of the lumbar spine and in optimising the parameters of lumbar surgical instruments.

Cite this article: M. Fu, Q. Ye, C. Jiang, L. Qian, D. Xu, Y. Wang, P. Sun, J. Ouyang. The segment-dependent changes in lumbar intervertebral space height during flexion-extension motion. Bone Joint Res 2017;6:245–252. DOI: 10.1302/2046-3758.64.BJR-2016-0245.R1.