Reinforcement of Percutaneous Pedicle Screw Fixation with Hydroxyapatite Granules in Patients with Osteoporotic Spine: Biomechanical Performance and Clinical Outcomes

Effects of anti-osteoporosis treatment in elderly patients with osteoporosis and lumbar discectomy and fusion

BACKGROUND

The effect of anti-osteoporosis treatment in elderly patients with osteoporosis and lumbar discectomy and fusion (LIF) for lumbar degenerative diseases is not well known.

OBJECTIVE

This study aimed to evaluate the effect of perioperative anti-osteoporosis treatment in the patients with osteoporosis and LIF.

METHODS

From January to December 2022, patients were divided into three groups according to the inclusive criteria: the normal group (Group A), the osteopenia group (Group B) and the osteoporosis group (Group C). Quantitative computed tomography (QCT), height of the intervertebral space (HIS), segmental sagittal angle (SSA), visual analogue scale (VAS) score and Oswestry Disability Index (ODI) were compared between the groups at the follow-up time. The serum Ca2 + , osteocalcin (OC), propeptide of type I procollagen (PINP) C-terminal cross-linking telopeptide of type I collagen (β-CTX) and 25-OH vitamin D (25-OH VD) levels were compared between the groups at the time of follow-up. Interbody fusion was graded on the X-ray and CT images at the follow-up time.

RESULTS

There were 165 patients in this study. There were significant differences in the mean age, mean score, HIS and SSA between the groups at the different follow-up times. There were significant differences in the concentrations of serum Ca2 + , OC, β-CTX, 25-OH VD and PINP at the sixth month after surgery between the groups. There were significant differences in the concentrations of serum Ca2 + , β-CTX and 25-OH VD between the pre-surgery and at six months after surgery in Group B and β-CTX and 25-OH VD in Group C. There was a significant difference in the degree of fusion between Group B and C (χ2= 5.6243, P< 0.05).

CONCLUSION

In elderly patients with LIF and osteoporosis, anti-osteoporosis therapy could reduce bone resorption and thus facilitate fusion. Anti-osteoporosis medication tends to enhance radiological, functional, and fusion short-term outcomes.

Biomechanical Study of 3 Osteoconductive Materials Applied in Pedicle Augmentation and Revision for Osteoporotic Vertebrae: Allograft Bone Particles, Calcium Phosphate Cement, Demineralized Bone Matrix

OBJECTIVE

This study assessed biomechanical properties of pedicle screws enhanced or revised with 3 materials. We aimed to compare the efficacy of these materials in pedicle augmentation and revision.

METHODS

One hundred twenty human cadaveric vertebrae were utilized for in vitro testing. Vertebrae bone density was evaluated. Allograft bone particles (ABP), calcium phosphate cement (CPC), and demineralized bone matrix (DBM) were used to augment or revise pedicle screw. Post the implantation of pedicle screws, parameters such as insertional torque, pullout strength, cycles to failure and failure load were measured using specialized instruments.

RESULTS

ABP, CPC, and DBM significantly enhanced biomechanical properties of the screws. CPC augmentation showed superior properties compared to ABP or DBM. ABP-augmented screws had higher cycles to failure and failure loads than DBM-augmented screws, with no difference in pullout strength. CPC-revised screws exhibited similar strength to the original screws, while ABP-revised screws showed comparable cycles to failure and failure loads but lower pullout strength. DBM-revised screws did not match the original screws' strength.

CONCLUSION

ABP, CPC, and DBM effectively improve pedicle screw stability for pedicle augmentation. CPC demonstrated the highest efficacy, followed by ABP, while DBM was less effective. For pedicle revision, CPC is recommended as the primary choice, with ABP as an alternative. However, using DBM for pedicle revision is not recommended.

Effect of bone cement-reinforced pedicle screws combined with fusion repositioning therapy on lumbar spine function and postoperative complications in patients with severe lumbar spondylolisthesis

Objective

To retrospectively study the efficacy of bone cement-enhanced pedicle screws combined with interbody fusion reduction in the treatment of severe lumbar spondylolisthesis, its effect on lumbar function and complications.

Methods

From January 2019 to June 2021, 82 cases of severe lumbar spondylolisthesis in our hospital were analyzed. According to the different treatment plans, the patients were divided into two groups: A and B, in which group A patients were treated with pedicle screws combined with fusion and reduction, and group B patients were treated with bone cement reinforced pedicle screws combined with fusion and reduction. Perioperative indexes, pain severity (VAS), Oswestry dysfunction index (ODI), and low back and leg pain score of Japan Orthopedic Association (JOA), spondylolisthesis reduction, intervertebral space height, intervertebral foramen height, complications, and screw loosening were compared between the two groups.

Results

There was no significant difference in the amount of intraoperative bleeding between group A and group B (P > 0.05). The operation time of group B was longer than that of group A, and the hospitalization time was shorter than that of group A. The vertebral fusion rate of group B was higher than that of group A (P < 0.05). The VAS, ODI and JOA scores at the last follow-up in both groups were lower than those before surgery, and group B was lower than group A (P < 0.05). Compared with the preoperative period, the postoperative slippage degree grading improved in both groups, while the improvement rate in group B was higher than that in group A (P < 0.05). At the last follow-up, the scores of intervertebral foramen height and intervertebral space height in both groups were higher than those before operation, and those in group B were higher than those in group A (P < 0.05). There was no difference in the incidence of complications and screw loosening between the two groups (P > 0.05).

Conclusion

Compared with conventional screw treatment, bone cement-reinforced pedicle screws combined with fusion repositioning can further improve the repositioning rate of slipped vertebrae in the treatment of severe LSL, while achieving a better intervertebral fusion rate. Therefore, the treatment of severe LSL with bone cement reinforced pedicle fusion and reduction is a safe and effective method.

Computed Tomography-Based Prediction of Lumbar Pedicle Screw Loosening

Objective

Pedicle screw loosening is one of the main complications after pedicle screw fixation. However, there are few reliable measures for prediction of screw loosening. The current study was carried out to find an effective method to use preoperative CT scanning as a predictor of screw loosening in the elderly patients and provide guidance for preoperative surgical planning.

Methods

Patients who were treated with lumbar pedicle screw fixation procedure in our department for degenerative lumbar disorders between January 2015 and January 2021 were retrospectively included in the current study. CT scan attenuation of each vertebra was measured with Hounsfield units (HU). Screw loosening was determined in postoperatively X-ray tests. One-way analysis of variance (ANOVA) and receiver operating characteristic (ROC) curve analysis were carried out with IBMSPSS 24.00 software.

Results

Screw loosening was observed in 44 of 215 patients (124 male, 91 female, average age 58.4 ± 7.6 years) during a mean follow-up time of 19.0 ± 11.2 months (range 12-32 months). No significant differences were found among the patients concerning patient gender, BMI, habit of smoking, and whether or not the patient had diabetes or suffered from spondylolisthesis (P > 0.05). The average HU value of lumbar vertebra was 122.4 ± 32.8 HU in the screw loosening group and 142.4 ± 38.2 HU in the control group, and the difference was significant (P < 0.01). ROC curve analysis revealed that the average HU value of L1-L5 has a relatively larger area under the curve (AUC) of 0.689 (95% CI: 0.605-0.773). With the sensitivity of 68% and specificity of 57%, a HU cut-off value of ≤124 HU is a plausible cut-off point to predict screw loosening.

Conclusions

A prospective CT scan HU value-based prediction can be used to decide whether or not to use screw augmentation methods. A cut-off L1-L5 average HU value of 124 HU can be used as an independent risk factor for screw loosening in instrumented lumbar vertebra. More predictive indexes should be involved to achieve higher sensitivity and specificity in future clinical practice.