Laminotomy in adults: technique and results

Biomechanical effects of the cephalad extent of laminotomy

PURPOSE

The superior aspect of the unilateral laminotomy for bilateral decompression (ULb) typically corresponds with the superior ligamentum flavum attachment. Unlike lateral expansion, cranial expansion is considered a viable option to ensure sufficient decompression. The aim of this study was to investigate how cranial expansion affects the biomechanical stability in the lumbar spine.

METHODS

Range of motion of eight fresh-frozen human cadaveric L1-L5 specimens was assessed in flexion-extension, lateral bending (LB), and axial rotation (AR). The workflow comprised testing in the intact state and after L3-4 ULb with sequential increase of the cephalad extent over 4 steps: (1)25% of the lamina height = insertion of Ligamentum Flavum, (2)50%, (3)75%, and (4)100%. Throughout all steps, constant mediolateral and caudal dimensions were maintained.

RESULTS

Even though within the tested sequences of the workflow an overall significant change was eminent for extension (p = 0.002), right LB (p = 0.030), and left AR (p = 0.009), no significant differences was detected when comparing their five different states pairwise. At L2-3, no overall significant changes were detected for all six motion directions (p ≥ 0.107).

CONCLUSION

ULb induced minor instabilities to the operated segment and no instability to the cranial adjacent segment. However, the absolute increase remained small under the tested conditions, suggesting that unilateral laminotomy is a safe technique at all cranial extents. With a bone-sparing laminotomy preferred, extending cranially appears to be a viable option to achieve sufficient decompression.

Database analysis comparing incidence and complication rates between inpatient and outpatient laminotomies for lumbar disc herniation

Background

Lumbar disc herniation (LDH) is a common condition that can be characterized with disabling pain. While most patients recover without surgery, some still require operative intervention. The epidemiology and trends of laminotomy for LDH have not been recently studied, and current practice patterns might be different from historical norms. This study aimed to investigate the trends of inpatient and outpatient laminotomies for LDH and compare complication rates between these two sites of service.

Methods

A large, national database was utilized to identify patients > 8 years old who underwent a laminotomy for LDH between 2009 and 2019. Two cohorts were created based on site of surgery: inpatient versus outpatient. The outpatient cohort was defined as patients who had a length of stay less than 1 day without any associated hospitalization. Epidemiologic analyses for these cohorts were performed by demographics. Patients in both groups were then 1:1 propensity-score matched based on age, sex, insurance type, geographic region, and comorbidities. Ninety-day postoperative complications were compared between cohorts utilizing multivariate logistic regressions.

Results

The average incidence of laminotomy for LDH was 13.0 per 10,000 persons-years. Although the national trend in incidence had not changed from 2009 to 2019, the proportion of outpatient laminotomies significantly increased in this time period (p=.02). Outpatient laminotomies were more common among younger and healthier patients. Patients with inpatient laminotomies had significantly higher rates of surgical site infections (odds ratio [OR] 1.61, p<.001), venous thromboembolism (VTE) (OR 1.96, p<.001), hematoma (OR 1.71, p<.001), urinary tract infections (OR 1.41, p<.001), and acute kidney injuries (OR 1.75, p=.001), even when controlling for selected confounders.

Conclusions

Our study demonstrated an increasing trend in the performance of laminotomy for LDH toward the outpatient setting. Even when controlling for certain confounders, patients requiring inpatient procedures had higher rates of postoperative complications. This study highlights the importance of carefully evaluating the advantages and disadvantages of performing these procedures in an outpatient versus inpatient setting.

Comparative Biomechanical Stability of the Fixation of Different Miniplates in Restorative Laminoplasty after Laminectomy: A Finite Element Study

A novel H-shaped miniplate (HSM) was specifically designed for restorative laminoplasties to restore patients' posterior elements after laminectomies. A validated finite element (FE) model of L2/4 was utilized to create a laminectomy model, as well as three restorative laminoplasty models based on the fixation of different miniplates after a laminectomy (the RL-HSM model, the RL-LSM model, and the RL-THM model). The biomechanical effects of motion and displacement on a laminectomy and restorative laminoplasty with three different shapes for the fixation of miniplates were compared under the same mechanical conditions. This study aimed to validate the biomechanical stability, efficacy, and feasibility of a restorative laminoplasty with the fixation of miniplates post laminectomy. The laminectomy model demonstrated the greatest increase in motion and displacement, especially in axial rotation, followed by extension, flexion, and lateral bending. The restorative laminoplasty was exceptional in preserving the motion and displacement of surgical segments when compared to the intact state. This preservation was particularly evident in lateral bending and flexion/extension, with a slight maintenance efficacy observed in axial rotation. Compared to the laminectomy model, the restorative laminoplasties with the investigated miniplates demonstrated a motion-limiting effect for all directions and resulted in excellent stability levels under axial rotation and flexion/extension. The greatest reduction in motion and displacement was observed in the RL-HSM model, followed by the RL-LSM model and then the RL-THM model. When comparing the fixation of different miniplates in restorative laminoplasties, the HSMs were found to be superior to the LSMs and THMs in maintaining postoperative stability, particularly in axial rotation. The evidence suggests that a restorative laminoplasty with the fixation of miniplates is more effective than a conventional laminectomy due to the biomechanical effects of restoring posterior elements, which helps patients regain motion and limit load displacement responses in the spine after surgery, especially in axial rotation and flexion/extension. Additionally, our evaluation in this research study could benefit from further research and provide a methodological and modeling basis for the design and optimization of restorative laminoplasties.

A multilevel posterior tension band-sparing laminectomy for intraspinal lesions: patient series

BACKGROUND

Minimally invasive spine surgery (MISS) represents a major development in spinal tumor surgery. However, considering that many intradural lesions compromise multiple spinal segments, MISS has certain limitations. Thus, some intraspinal lesions still require traditional approaches. Because laminectomy has been shown to predispose patients to kyphosis, laminoplasty and hemilaminectomy are the most widely used approaches to preserve the posterior tension band (PTB). However, these techniques are not devoid of complications. To overcome these issues, the authors modified a previously described technique to preserve the PTB while removing various types of intradural lesions. This procedure was originally designed to treat lumbar stenosis and was modified to avoid muscle ischemia during long procedures.

OBSERVATIONS

Between 2014 and 2021, the authors found 17 cases of spinal lesions with a minimum of 2 years of follow-up after surgical treatment using their approach. No significant postoperative changes in the paraspinal Goutallier grade or spinal angles were observed. The cross-sectional area of the measured paraspinal muscles decreased 6% postoperatively. By performing certain technical modifications in this PTB-sparing (PBS) laminectomy, the authors avoided ipsilateral muscle ischemia.

LESSONS

In this initial series, PBS laminectomy proved to be a safe, versatile, inexpensive, and reliable technique to remove intraspinal lesions.

Biomechanical evaluation of reconstruction of the posterior complex in restorative laminoplasty with miniplates

OBJECTIVE

To evaluate the biomechanical effects of different miniplates on restorative laminoplasty.

METHODS

Assembled restorative laminoplasty models were developed based on 3D printed L4 lamina. Based on different internal fixations, the research was divided into H-shaped miniplates (HSMs) group, two-hole miniplates (THMs) group, and L-shaped miniplates (LSMs) group. The static and dynamic compression tests were analyzed to investigate the biomechanical effects of different internal fixations in restorative laminoplasty, until the failure and fracture of miniplates, or the collapse of miniplates. The static compression tests adopted the speed control mode, and the dynamic fatigue compression tests adopted the load control mode.

RESULTS

The "door close" and the collapse of lamina occurred in THMs group and LSMs group, and plate break occurred in LSMs group. However, these phenomenon was absent in HSMs group, and only plate crack around a screw and looseness of a screw tail cap were found in HSMs group. The sustainable yield load of HSMs group was greater than that of THMs group and LSMs group (P < 0.05). No significant difference in yielding-displacement was found between HSMs group and LSMs group (P > 0.05), while both were much less than that of THMs (P < 0.05). Moreover, the compressive stiffness and the axial displacement under the same mechanical load were arranged as follows: HSMs group > LSMs group > THMs group (P < 0.05). The results of dynamic compression test revealed that the peak load of HSMs group could reached 873 N and was 95% of the average yield load of the static compression, and was better than that in THMs group and LSMs group (P < 0.05). Besides, according to the fatigue life-peak load diagram, the ultimate load of HSMs group was more than twice that of THMs group or LSMs group.

CONCLUSIONS

The mechanical strength of H-shaped miniplates was superior to two-hole miniplates and L-shaped miniplates in maintaining spinal canal enlargement and spinal stability, and was more excellent in fatigue stability and ultimate load.

[Biomechanical analysis of miniplate fixation systems in restorative laminoplasty for spinal canal reconstruction]

OBJECTIVE

To investigate the biomechanical properties of H-shaped and L-shaped miniplate fixation systems (H-MFS and L-MFS, respectively) in restorative laminoplasty for spinal canal reconstruction (RL-SCR).

METHODS

Laminectomy was performed in a 3D printed L4 vertebral model followed by RL-SCR using H-MFS or L-MFS, and the biomechanical properties of the reconstructed models were evaluated using static and dynamic compression tests. Biomechanical analyses of RL-SCR were also conducted in finite element models of the L3-L5 vertebrae with normal assignment (NA), laminectomy, or fixation with H-MFS or L-MFS, and the range of motion (ROM) of L3-L4 and L4-L5 was evaluated.

RESULTS

In static compression test, the sustained yield load, compression stiffness, yield displacement and axial displacement- axial load were all significantly greater in H-MFS group (P < 0.05). Door closing, lamina collapse and plate breakage occurred in all the models in L-MFS group, and only some models in H-MFS group showed plate cracks and screw loosening. In dynamic compression tests, the peak load in H-MFS group reached 873 N (which was 95% of the average yield load in static compression), significantly greater than that in L-MFS group (P < 0.05). The ultimate load in L-MFS group was only 46.59% of that in H-MFS group (P>0.05). In finite element analysis, the ROM of the L3-L4 and L4- L5 segments were significantly smaller in NA, H-MFS and L-MFS groups than in laminectomy group. Compared with NA group, H-MFS group showed a greater ROM during extension, and L-MFS group showed greater ROM in flexion, extension, bending, and rotation; The overall ROM of the vertebral segments decreased in the order of laminectomy group, L-MFS group, H-MFS group, and NA group.

CONCLUSION

Laminectomy causes structural destruction of the posterior column of the spine to affect its biomechanical stability. RL-SCR can effectively maintain the biomechanical stability of the spine, and H-MFS is superior to L-MFS in maintaining the integrity and biomechanical properties of the reconstructed spinal canal.

Laminectomy Versus Laminoplasty in the Surgical Management of Long-Segment Intradural Spinal Tumors: Any Difference in Neurological Outcomes?

Background:

Previous comparative studies have shown that apart from lack of any significant difference in neurologic outcomes between laminoplasty and laminectomy following resection of intradural spinal tumours, spinal column issues such as postoperative deformities, malalignment, and adjacent level disease have also been clearly demonstrated to be quite similar for both techniques. However, there is no study yet that describes any difference in neurologic outcomes for long-segment intradural lesions as a rare subset of these lesions (in terms of number of spinal segments involved) following surgical management between these two techniques.

Materials and Methods:

This is a retrospective review of surgical treatment with either laminectomy or laminoplasty done for patients with long-segment intradural tumors at a tertiary health-care institution in India.

Results:

Out of over 167 patients surgically treated for intradural tumors during the study period, a total of 60 patients were included in the evaluation. The long-segment tumors were intramedullary in 22 (36.7%) patients and intradural-extramedullary in the remaining 38 (63.3%) patients. No patient in both cohorts had any revisional surgery after initial resection or any serious complications. The incidence of neurologic function remaining unchanged at the end of follow-up was similar between laminoplasty and laminectomy (12.5% vs. 11.1%). There was no significant correlation between the preoperative McCormick score and postoperative McCormick score (P > 0.05 at 95% degree of confidence; Spearman's rho = 0.028), suggesting that functional outcomes were not dependent on the initial neurologic status. Multivariate logistic regression analysis showed that : the two independent variables (Extent of surgery and Choice of procedure) were not significant predictors of the dependent variable (Functional outcome following surgery) (odds ratio = 3.836; p = 0.071).

Conclusion:

This retrospective evaluation demonstrates laminoplasty not to be more or less likely to have any better functional outcome or need for revision compared to laminectomy in the resection of long-segment intradural lesions. A quality randomized controlled study on a much larger scale will be required to validate this finding.

Spinal Nerves Schwannomas: Experience on 367 Cases-Historic Overview on How Clinical, Radiological, and Surgical Practices Have Changed over a Course of 60 Years

Background

Spinal schwannomas are common benign spinal tumors. Their treatment has significantly evolved over the years, and preserving neurological functions has become one of the main treatment goals together with tumor resection.

Study Design and Aims

Retrospective review focused on clinical assessment, treatment techniques, and outcomes.

Methods

A retrospective study on our surgical series was performed. Clinical and operative data were analyzed. In regard to neurophysiologic monitoring, patients were retrospectively divided into two groups comparing the outcomes before and after introduction of routine intraoperative neurophysiology tests.

Results

From 1951 to 2010, 367 patients overall were treated. Diagnosis was obtained using angiography and/or myelography (pre-CT era), MRI, or CT scan. A posterior spinal approach was used for most patients; complex approaches were adopted for treatment of giant/dumbbell tumors. A trend of neurophysiology monitoring decreasing the rate of post-op neurological deficits was observed but was not statistically significant enough to draft evidence-based conclusions.

Conclusions

Clinical and radiological assessment of spinal schwannomas has markedly changed over the course of 50 years. Diagnostic tools have improved, and detection of recurrence has become way more sensitive. Neurophysiologic monitoring has become a useful intraoperative tool to guide resection and prevent post-op neurological impairment.

[Application of resorbable plates for fixation of a laminotomy flap]

The paper describes a new technology - application of resorbable plates and pins for securing a laminotomy flap in children's neurosurgery. Four patients were operated on at our clinic. We describe in detail a surgical technique and compare it with a traditional fixation technique using ligatures.

Post laminoplasty cervical kyphosis-Case report

INTRODUCTION

Cervical kyphosis is a progressive cervical sagittal plane deformity that may cause a reduction in the ability to look horizontally, breathing and swallowing difficulties, sense of thoracic oppression and social isolation. Moreover, cervical kyphosis can cause myelopathy due to a direct compression by osteo-articular structures on the spinal cord or to a transitory ischaemic injury. The treatment of choice is surgery. The goals of surgery are: nervous structures decompression, cervical and global sagittal balance correction and vertebral stabilization and fusion.

PRESENTATION OF CASE

In October 2008 a 35 years old woman underwent surgical removal of a cervical-bulbar ependymoma with C1-C5 laminectomy and a C2-C5 laminoplasty. Five months after surgery, the patient developed a kyphotic posture, with intense neck and scapular girdle pain. The patients had a flexible cervical kyphosis. Therefore, we decided to perform an anterior surgical approach. We performed a corpectomy C4-C5 in order to achieve the anterior decompression; we placed a titanium expansion mesh.

DISCUSSION

Cervical kyphosis can be flexible or fixed. Some authors have reported the use of anterior surgery only for flexible cervical kyphosis as discectomy and corpectomy. This approach is useful for anterior column load sharing however it is not required for deformity correction.

CONCLUSION

The anterior approach is a good surgical option in flexible cervical kyphosis. It is of primary importance the sagittal alignment of the cervical spine in order to decompress the nervous structures and to guarantee a long-term stability.

Results of cervical recapping laminoplasty: gross anatomical changes, biomechanical evaluation at different time points and degrees of level involvement

Background

Recapping laminoplasty has become the frequently-used approach to the spinal canal when bone decompression of the vertebral canal is not the goal. However, what changes will occur after surgery, and whether recapping laminoplasty can actually reduce the risk of delayed deformities remains unknown.

Methodology

We designed an animal experiment using a caprine model, and partitioned the animals into in vitro and in vivo surgical groups. We performed recapping laminoplasty on one group and laminectomy on another group. These animals were sacrificed six months after operating, cervical spines removed, biomechanically tested, and these data were compared to determine whether the recapping laminoplasty technique leads to subsequent differences in range of motion. Image data were also obtained before the surgery and when the animals were killed. Besides, we investigated the initial differences in kinetics between recapping laminoplasty and laminectomy. We did this by comparing data obtained from biomechanical testing of in vitro-performed recapping laminoplasty and laminectomy. Finally, we investigated the effect that longitudinal distance has on cervical mechanics. This was determined by performing a two-level recapping laminoplasty, and then extending the laminoplasty to the next level and repeating the mechanical testing at each step.

Principal Findings

There were three mainly morphological changes at the six months after laminoplasty: volume reduction and bone nonunion of the recapping laminae, irregular fibrosis formation around the facet joints and re-implanted lamina-ligamentous complex. In the biomechanical test, comparing with laminectomy, recapping laminoplasty didn’t show significant differences in the immediate postoperative comparison, while recapping laminoplasty demonstrated significantly decreased motion in flexion/extension six months later. Inclusion of additional levels in the laminotomy procedure didn’t lead to changes in immediate biomechanics.

Conclusions

Recapping laminoplasty can’t fully restore the posterior structure, but still reduced the risk of delayed cervical instability in a caprine model.