The Effect of Laminectomy with Instrumented Fusion Carried into the Thoracic Spine on the Sagittal Imbalance in Patients with Multilevel Ossification of the Posterior Longitudinal Ligament

[Application of ultrasonic bone scalpel system for laminectomy and posterior longitudinal ligament ossification block release combined with dekyphosis orthopedic surgery in treatment of multisegmental thoracic ossification of posterior longitudinal ligament]

Objective

To explore the safety and effectiveness of multisegmental thoracic ossification of posterior longitudinal ligament (T-OPLL) treated by laminectomy, posterior longitudinal ligament ossification block release combined with dekyphosis orthopedic surgery using ultrasonic bone scalpel system.

Methods

The clinical data of 8 patients with multisegmental T-OPLL treated with laminectomy, posterior longitudinal ligament ossification block release combined with dekyphosis orthopedic surgery using ultrasonic bone scalpel system between January 2020 and April 2023 was retrospectively analyzed. There were 3 males and 5 females; the age ranged from 41 to 67 years, with a mean of 57.1 years. The disease duration ranged from 3 to 74 months, with a mean of 33.4 months. Symptoms were progressive numbness and weakness of both lower limbs, unsteady walking, chest and back pain in 3 cases, and urinary and bowel dysfunction in 5 cases; 7 cases showed increased muscle strength of the lower limbs, hyperreflexia of the tendons, and a positive Babinski sign, and 1 case showed decreased muscle strength of the lower limbs, decreased skin sensation, decreased knee and Achilles tendon reflexes, and a negative pathologic sign. Multisegmental posterior longitudinal ligament ossification of thoracic spine was found in 8 cases, with 4-8 segments of ossification, and in 5 cases with multisegmental ossification of the ligamentum flavum. The preoperative Japanese Orthopaedic Association (JOA) thoracic spinal function score was 4.3±0.9, the visual analogue scale (VAS) score was 6.9±1.0, and the the kyphotic Cobb angle of the stenosis segment was (34.62±10.76)°. The operation time, intraoperative blood loss, and complications were recorded. VAS score was used to evaluate the back pain, JOA score was used to evaluate the thoracic spinal cord function and the JOA improvement rate was calculated, and the kyphotic Cobb angle of the stenosis segment was measured and the Cobb angle improvement rate was calculated.

Results

The operation time ranged from 210 to 340 minutes, with a mean of 271.62 minutes; intraoperative blood loss ranged from 900 to 2 100 mL, with a mean of 1 458.75 mL; the number of resected vertebral plates ranged from 4 to 8, with a mean of 6.1; dural tears and cerebrospinal fluid leakage occurred in 3 cases, and the incisions healed by first intention. All 8 cases were followed up 12-26 months, with a mean of 18.3 months. There was no complication such as loosening of internal fixator, breakage of screws and rods, and no significant progress of ossification. At last follow-up, the VAS score was 1.4±0.7, the JOA thoracic spinal function score was 9.8±0.7, and the the kyphotic Cobb angle of the stenosis segment was (22.12±8.28)°, all of which significantly improved when compared with preoperative ones ( t=11.887, P<0.001; t=13.015, P<0.001; t=7.395, P<0.001). The JOA improvement rate was 81.06%±10.93%, of which 5 cases were rated as excellent and 3 cases as good; the Cobb angle improvement rate was 36.51%±14.20%.

Conclusion

Laminectomy, posterior longitudinal ligament ossification block release combined with dekyphosis orthopedic surgery using ultrasonic bone scalpel system is a safe, effective, and simple method for the treatment of multisegmental T-OPLL, which is a feasible option.

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.

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.

Is It Necessary to Cross the Cervicothoracic Junction in Posterior Cervical Decompression and Fusion for Multilevel Degenerative Cervical Spine Disease? A Systematic Review and Meta-Analysis

BACKGROUND

Posterior cervical decompression and fusion (PCF) is a common procedure for treating patients with multilevel degenerative cervical spine disease. The selection of lower instrumented vertebra (LIV) relative to the cervicothoracic junction (CTJ) remains controversial. This study aimed to compare the outcomes of PCF construct terminating at the lower cervical spine and crossing the CTJ.

METHODS

A comprehensive literature search was performed for relevant studies in the PubMed, EMBASE, Web of Science, and Cochrane Library database. Complications, rate of reoperation, surgical data, patient-reported outcomes (PROs), and radiographic outcomes were compared between PCF construct terminating at or above C7 (cervical group) and at or below T1 (thoracic group) in patients with multilevel degenerative cervical spine disease. A subgroup analysis based on surgical techniques and indications was performed.

RESULTS

Fifteen retrospective cohort studies comprising 2071 patients (1163 in the cervical group and 908 in the thoracic group) were included. The cervical group was associated with a lower incidence of wound-related complications (RR, 0.58; 95% CI 0.36 to 0.92, p = 0.022; 831 patients in cervical group vs. 692 patients in thoracic group), a lower reoperation rate for wound-related complications (RR, 0.55; 95% CI 0.32 to 0.96, p = 0.034; 768 vs. 624 patients), and less neck pain at the final follow-up (WMD, -0.58; 95% CI -0.93 to -0.23, p = 0.001; 327 vs. 268 patients). However the cervical group also developed a higher incidence of overall adjacent segment disease (ASD, including distal ASD and proximal ASD) (RR, 1.87; 95% CI 1.27 to 2.76, p = 0.001; 1079 vs. 860 patients), distal ASD (RR, 2.18; 95% CI 1.36 to 3.51, p = 0.001; 642 vs. 555 patients), overall hardware failure (including hardware failure of LIV and hardware failure occurring at other instrumented vertebra) (RR, 1.48; 95% CI 1.02 to 2.15, p = 0.040; 614 vs. 451 patients), and hardware failure of LIV (RR, 1.89; 95% CI 1.21 to 2.95, p = 0.005; 380 vs. 339 patients). The operating time was reasonably shorter (WMD, -43.47; 95% CI -59.42 to -27.52, p < 0.001; 611 vs. 570 patients) and the estimated blood loss was lower (WMD, -143.77; 95% CI -185.90 to -101.63, p < 0.001; 721 vs. 740 patients) when the PCF construct did not cross the CTJ.

CONCLUSIONS

PCF construct crossing the CTJ was associated with a lower incidence of ASD and hardware failure but a higher incidence of wound-related complications and a small increase in qualitative neck pain, without difference in neck disability on the NDI. Based on the subgroup analysis for surgical techniques and indications, prophylactic crossing of the CTJ should be considered for patients with concurrent instability, ossification, deformity, or a combination of anterior approach surgeries as well. However, long-term follow-up outcomes and patient selection-related factors such as bone quality, frailty, and nutrition status should be addressed in further studies.

[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.