A novel injectable calcium phosphate-based nanocomposite for the augmentation of cannulated pedicle-screw fixation

Sun, Haolin; Liu, Chun L; Liu, Huiling; Bai, Yanjie; Zhang, Zheng; Li, Xuwen; Li, Chunde; Yang, Huilin; Yang, Lei

doi:10.2147/ijn.s131962

Cited by 17 publications

(20 citation statements)

References 20 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In standardized in vitro tests, CPN exhibited fluidity and dispersing ability similar to PMMA cements. These studies conclude that CPN is superior to PMMA in terms of biodegradability and bone growth induction [20], [21]. But as with all other calcium phosphate cements, CPN has an intrinsic mechanical strength much lower than PMMA cement because the compressive strength of CPN is only half that of PMMA after hardening.…”

Section: Introductionmentioning

confidence: 93%

A novel calcium phosphate–based nanocomposite for the augmentation of cement-injectable cannulated pedicle screws fixation: A cadaver and biomechanical study

Sun

Liu

et al. 2020

Journal of Orthopaedic Translation

Self Cite

View full text Add to dashboard Cite

Background/objectiveBoth polymethylmethacrylate (PMMA) and traditional calcium phosphate–based cements have some deficiencies as augmentation materials for pedicle screw fixation. Here, a novel calcium phosphate–based nanocomposite (CPN) for the augmentation of pedicle screw fixation was developed based on previous study, and the handling properties, biomechanical performance, and biodegradation behaviour of CPN were evaluated and compared with clinical PMMA by means of a cadaver study and animal tests.MethodsBone mineral density of the lumbar vertebrae was tested. Pedicle screws were placed into the lumbar vertebrae under the guidance of three dimensionally printed templates; each of which was designed based on computed tomography (CT) reconstruction of each vertebrae and augmented with either PMMA or CPN. X-ray and CT scan were used to evaluate the accuracy of screw placement and dispersion as well as interdigitation of bone cement. The axial pull-out strength and maximum torque were tested using a mechanical testing machine. Degradation behaviour of CPN was evaluated by in vitro immersion tests for 8 weeks and in vivo rabbit femur defect model for up to 6 months, respectively.ResultsStandard mechanical tests revealed that PMMA was much stronger than CPN after setting (compressive strength 95 vs. 49 MPa, respectively, p < 0.001). Results of the projection area and volume distribution of cement along the distal end of the screws revealed that CPN exhibited unique dispersing and interdigitation abilities compared with PMMA. Specifically, CPN dispersed uniformly and symmetrically along the screw, while PMMA was limited to the proximal part of the screw. Axial pull-out test results showed that the axial pull-out strengths of CPN- and PMMA-augmented pedicle screws were similar (1199 ± 225 N vs 1337 ± 483 N, respectively) and not significantly different (p = 0.47), although CPN was an intrinsically weaker material than PMMA. Similarly, CPN showed average torque values of 0.72 ± 0.31 N·m slightly lower than those of PMMA (0.96 ± 0.23 N·m), but statistically there was no significant difference between CPN and PMMA (p = 0.21). In a rabbit model of femoral bone defect, the implanted CPN maintained its clear boundary and there is no disintegration in the cement clump after 20 days and 24 weeks, and there was moderate bioabsorption of CPN and clearly new bone ingrowth at the absorbed sites after 24 weeks.ConclusionA new nanocomposite cement CPN, designed for replacing the nondegradable PMMA cement and overcoming the mechanical inferiority of calcium phosphate cement, was evaluated for its biomechanical and biodegradation behaviours in cement-injectable cannulated pedicle screws (CICPS) application. Although CPN is a mechanically weaker material than PMMA, CPN demonstrates similar biomechanical properties to PMMA in the application of augmentation for CICPS fixation in cadaveric vertebrae. This improvement in biomechanical property is attributed to a better dispersion and interdigitation mode of CPN. In a...

show abstract

Section: Introductionmentioning

confidence: 93%

A novel calcium phosphate–based nanocomposite for the augmentation of cement-injectable cannulated pedicle screws fixation: A cadaver and biomechanical study

Sun

Liu

et al. 2020

Journal of Orthopaedic Translation

Self Cite

View full text Add to dashboard Cite

show abstract

“…Numerous studies have focused on different pedicle screw designs to prevent screw loosening. These designs include screws with an increased outer diameter or length [8], different thread profiles [9][10][11], a cylindrical or conical core [12][13][14], expanding screws [15,16] and cannulated screws with polymethylmethacrylate (PMMA) cement augmentation [14,[17][18][19]. All of these screw designs are continuously studied.…”

Section: Introductionmentioning

confidence: 99%

“…All of these screw designs are continuously studied. Among these screw designs, cannulated screws in particular have an efficient alternative and innovative design for preventing osteoporotic incidents when used with cement augmentation [14,17,[19][20][21].…”

Section: Introductionmentioning

confidence: 99%

“…In osteoporotic bone, cannulated screws with cement fixation have been well described to enhance the screw holding power due to the infiltration of PMMA cement into the trabecular bone [14,17,[19][20][21]. However, to the authors' knowledge, few available reports have systematically assessed the combined effects of thread profiles and cement augmentation on the screw anchoring power in osteoporotic bone.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Biomechanical comparison of pedicle screw fixation strength in synthetic bones: Effects of screw shape, core/thread profile and cement augmentation

et al. 2020

View full text Add to dashboard Cite

Pedicle screw loosening resulting from insufficient bone-screw interfacial holding power is not uncommon. The screw shape and thread profile are considered important factors of the screw fixation strength. This work investigated the difference in pullout strength between conical and cylindrical screws with three different thread designs. The effects of the thread profiles on the screw fixation strength of cannulated screws with or without cement augmentation in osteoporotic bone were also evaluated. Commercially available artificial standard L4 vertebrae and low-density polyurethane foam blocks were used as substitutes for healthy vertebrae and osteoporotic bones, respectively. The screw pullout strengths of nine screw systems were investigated (six in each). These systems included the combination of three different screw shapes (solid/cylindrical, solid/conical and cannulated/cylindrical) with three different thread profiles (fine-thread, coarse-thread and dual-core/dual-thread). Solid screws were designed for the cementless screw fixation of vertebrae using the standard samples, whereas cannulated screws were designed for the cemented screw fixation of osteoporotic bone using low-density test blocks. Following specimen preparation, a screw pullout test was conducted using a material test machine, and the maximal screw pullout strength was compared among the groups. This study demonstrated that, in healthy vertebrae, both the conical and dual-core/dual-thread designs can improve pullout strength. A combination of the conical and dual-core/dual-thread designs may achieve optimal postoperative screw stability. However, in osteoporotic bone, the thread profile have little impact on the screw fixation strength when pedicle screws are fixed with cement augmentation. Cement augmentation is the most important factor contributing to screw pullout fixation strength as compared to screw designs.

show abstract

“…Various methods of pedicle screw fixation have been used including minimally invasive percutaneous screw fixation, open pedicle screw insertion, and more recent trajectories including the cortical screw have gained popularity. To achieve improved stability and purchase, vertebral body and pedicle screw augmentation (kyphoplasty via the central screw cannulation and distal holes, and transpedicle injection) utilizing different bone cements such as calcium apatite cement (CAC), injectable calcium phosphate (CaP) and polymethylmethacrylate (PMMA) have been trialled. Multiple techniques of cement delivery are currently in practice.…”

Section: Introductionmentioning

confidence: 99%

Technical Note: Pedicle Cement Augmentation with Proximal Screw Toggle and Loosening

Choy

Walsh

Phan

et al. 2019

Orthopaedic Surgery

View full text Add to dashboard Cite

Background Cement augmentation is a technique used to increase the stability and purchase of pedicle screws in poor quality bone. Various methods can be applied for cement delivery, such as cement injection before screw placement and the use of fenestrated screws. However, potential problems can arise with the use of cement augmentation. Case Presentation A 66‐year‐old man with a lower trunk deformity, severe kyphosis, and sagittal imbalance following fusion (L2‐5), with minimal comorbidities, was referred to our unit 9 months after surgery. Pain and progressive kyphosis were investigated clinically and radiographically with computed tomography (CT) scans to assess the status of the hardware and fusion. CT imaging revealed that cement was present only at the distal tip of the fenestrated screws at the L4 vertebral level. A non‐union was present along with loosening and a halo around the body of the pedicle screws, and there was evidence of pullout of inferior screws. Conclusion Single‐level cement augmentation of pedicle screw in a posterior construct and distal tip cement augmentation of the screw results in a fixed pivot point. Micromotion in cranio‐caudal loading during flexion and extension may result in screw toggling with the single‐level cement‐augmented tip as a fulcrum. This may cause screw loosening, which can lead to pullout and loss of construct stability. The halo around the screw suggests bone loss and/or a fibrous tissue interface, which further complicates revision surgery. Stress shielding and polymethylmethacrylate cement present additional difficulties. The findings of this technical note question the risks and benefits of cement‐augmented fenestrated pedicle screw fixation for spinal fusion. Although incidences of such cases are uncommon, surgeons should perform this technique with caution. Accurate restoration of lumbar lordosis during index procedures is important to minimize the risk of construct failure.

show abstract

A novel injectable calcium phosphate-based nanocomposite for the augmentation of cannulated pedicle-screw fixation

Cited by 17 publications

References 20 publications

A novel calcium phosphate–based nanocomposite for the augmentation of cement-injectable cannulated pedicle screws fixation: A cadaver and biomechanical study

A novel calcium phosphate–based nanocomposite for the augmentation of cement-injectable cannulated pedicle screws fixation: A cadaver and biomechanical study

Biomechanical comparison of pedicle screw fixation strength in synthetic bones: Effects of screw shape, core/thread profile and cement augmentation

Technical Note: Pedicle Cement Augmentation with Proximal Screw Toggle and Loosening

Contact Info

Product

Resources

About