-
PloS One 2021Although the pedicle is routinely used as a surgical fixation site, the pedicle wall bone area fraction (bone area per unit area) and its distribution at the isthmus of...
BACKGROUND
Although the pedicle is routinely used as a surgical fixation site, the pedicle wall bone area fraction (bone area per unit area) and its distribution at the isthmus of the pedicle remain unknown. The bone area fraction at the pedicle isthmus is an important factor contributing to the strength of pedicle screw constructs. This study investigates the lumbar pedicle wall microstructure based on micro-computed tomography.
METHODS
Six fresh-frozen cadaveric lumbar spines were analyzed. Left and right pedicles of each vertebra from L1 to L5 were resected for micro-computed tomography scanning. Data was analyzed with custom-written software to determine regional variation in pedicle wall bone area fraction. The pedicular cross-section was divided into four regions: lateral, medial, cranial, and caudal. The mean bone area fraction values for each region were calculated for all lumbar spine levels.
RESULTS
The lateral region showed lower bone area fraction than the medial region at all spinal levels. Bone area fraction in the medial region was the highest at all levels except for L4, and the median values were 99.8% (95.9-100%). There were significant differences between the lateral region and the caudal region at L1, L2 and L3, but none at L4 and L5. The bone area fraction in the lateral region was less than 64% at all spinal levels and that in the caudal region was less than 67% at the L4 and L5 levels.
CONCLUSIONS
This study provides initial detailed data on the lumbar pedicle wall microstructure based on micro-computed tomography. These findings may explain why there is a higher incidence of pedicle screw breach in the pedicle lateral and caudal walls.
Topics: Aged; Female; Humans; Lumbar Vertebrae; Male; Middle Aged; X-Ray Microtomography
PubMed: 34237065
DOI: 10.1371/journal.pone.0253019 -
In Vivo (Athens, Greece) 2021Surgical treatment for spinal deformity aims to correct malformation, release the nerves, and reconstruct spinal stability. To explore and develop a new improved spinal...
BACKGROUND/AIM
Surgical treatment for spinal deformity aims to correct malformation, release the nerves, and reconstruct spinal stability. To explore and develop a new improved spinal correction system (ISCS) for clinical application, we studied the stability and biomechanical characteristics of the ISCS through finite element analysis and comparison of the ISCS with the pedicle screw and rod system (PSRS).
PATIENTS AND METHODS
Using L1-L3 CT image data of a normal adult male lumbar spine for establishment of L1-L3 finite element model, we established posterior internal fixation models for a comparative finite element analysis of PSRS and ISCS. An axial load of 500 N and a moment of 10 N•m were applied to L1 to simulate flexion, extension, lateral bending, and axial rotation. Stress distribution characteristics, load sharing, strain bending stiffness and strain angle change of the models were measured.
RESULTS
In flection and extension directions, the maximum stress of the L2 vertebral body and the L1/2 and L2/3 discs in PSRS was less than that of ISCS. In lateral bending and axial rotation directions, the maximum stress between PSRS and ISCS was similar. However, the stress shielding rate of L2, L1/2, and L2/3 intervertebral discs in ISCS was significantly lower than that of PSRS. We also found that both models had similar angular displacement and maximum displacement in lateral bending direction, but PSRS had a lower angular displacement and maximum displacement in flection and extension directions. Finally, we showed that PSRS had similar angular displacement and a lower maximum displacement compared with ISCS in axial rotation, whereas ISCS had lower bending stiffness than PSRS in different directions.
CONCLUSION
ISCS can effectively fix spinal deformities compared to PSRS. ISCS provides a new option for orthopedic surgery treatment of scoliosis and, therefore, warrants further clinical studies in patients with other spinal deformities.
Topics: Biomechanical Phenomena; Finite Element Analysis; Humans; Lumbar Vertebrae; Male; Pedicle Screws; Spinal Fusion
PubMed: 34182497
DOI: 10.21873/invivo.12491 -
BMC Musculoskeletal Disorders Nov 2017One- and two-level lumbar interbody fusion with unilateral instrumentation is as effective as that with bilateral instrumentation. The height of the interbody cage...
The role of cage height on the flexibility and load sharing of lumbar spine after lumbar interbody fusion with unilateral and bilateral instrumentation: a biomechanical study.
BACKGROUND
One- and two-level lumbar interbody fusion with unilateral instrumentation is as effective as that with bilateral instrumentation. The height of the interbody cage influences the operated segment stability and the fusion technique success. The purpose of this research was to determine the effect of the fusion cage height (i.e. long and short) on both the stability (based on flexibility measures) and load sharing of the unilateral and bilateral instrumented transforaminal lumbar interbody fusion (TLIF) technique.
METHODS
The flexibility and load sharing tests were performed on seven human lumbar spines. Different configurations combining a long or short cage with a unilateral, bilateral, or no posterior fixation were used to stabilize the operated segment. Two sets of modular cages were designed for each type of test to simulate the long and short cages. During the flexibility test, a pure-moment load of 7.5 Nm was applied. The range of motion (ROM) was recorded for flexion-extension, lateral bending, and axial rotation. During the load sharing test, an axial-compression load of 400 N was applied. The load bearing of the cages was recorded using a cage-embedded load cell.
RESULTS
When the fusion cage height decreased 2 mm, the segment flexibility with unilateral fixation showed a significant increase in the ROM for flexion-extension, lateral bending, and axial rotation of 74.9, 83.8, and 175.2% (P < 0.01), respectively. In contrast, for bilateral fixation, the height decrease resulted in no significant change in ROM for flexion-extension (P = 0.686), lateral bending (P = 0.698), and axial rotation (P = 0.133). Using a short fusion cage, the load bearing decreased in 17.1, 21.5, and 54.1% (P < 0.05) for the cage alone, unilateral, and bilateral fixation, respectively.
CONCLUSIONS
A cage longer than the intervertebral space should be chosen to increase the stability and intervertebral graft load borne when performing TLIF with unilateral instrumentation.
Topics: Aged; Biomechanical Phenomena; Cadaver; Female; Humans; Intervertebral Disc Degeneration; Lumbar Vertebrae; Male; Middle Aged; Pedicle Screws; Prostheses and Implants; Prosthesis Design; Radiography; Range of Motion, Articular; Spinal Fusion; Weight-Bearing
PubMed: 29162074
DOI: 10.1186/s12891-017-1845-1 -
Revista Da Associacao Medica Brasileira... 2014The objective of this review is to reveal the quality of published data and the effect size of DPFs compared to rigid fixation in lumbar spine. (Review)
Review
OBJECTIVE
The objective of this review is to reveal the quality of published data and the effect size of DPFs compared to rigid fixation in lumbar spine.
SUMMARY OF BACKGROUND DATA
since 2002, several dynamic pedicle fixation (DPF) systems have been developed with the aim to stabilize the spine without the undesirable effects of rigid lumbar spine fixation. Nearly ten years later, there are several studies on these dynamic systems.
METHODS
A systematic review was done in MEDLINE/PubMED, Embase, Cochrane Central Register of Randomized Trials and Google Scholar to assess the quality of published literature and the available studied outcomes in randomized controlled trials of DPF.
RESULTS
Only three papers described randomized trials studying DPF. One of them focused on protection of adjacent level disease provided by DPF.
CONCLUSION
It was not possible to reveal any evidence for benefits using DPF compared to rigid fixation in surgery for lumbar spine.
Topics: Humans; Internal Fixators; Lumbar Vertebrae; Publishing; Quality Assurance, Health Care; Randomized Controlled Trials as Topic; Spinal Fractures; Spinal Fusion; Surgical Fixation Devices; Treatment Outcome
PubMed: 24919003
DOI: 10.1590/1806-9282.60.02.013 -
Der Unfallchirurg Apr 2022The goal of surgery for spinal injuries is fracture reduction, fixation and stable healing in a physiological position. Several open and minimally invasive surgical...
BACKGROUND
The goal of surgery for spinal injuries is fracture reduction, fixation and stable healing in a physiological position. Several open and minimally invasive surgical techniques are available.
OBJECTIVE
The extent of open reduction and the fixation potential achieved by the AOSpine (AT) and Kluger (KT) techniques were compared. The influence of fracture morphology, age, sex, and bone quality on fracture reduction and secure fixation was investigated.
MATERIAL AND METHODS
In this monocentric retrospective cohort study data of patients with traumatic thoracolumbar and lumbar fractures treated by AT or KT were analyzed. The bisegmental kyphotic angle (bGDW) of each injured spinal segment was determined. Normal bGDW values were extrapolated from the literature. The change of bGDW over time was analyzed under consideration of the bone quality in Hounsfield units (HU), injury severity according to the AOSpine classification, gender and age of patients.
RESULTS
A total of 151 data sets were evaluated. The AT and KT methods achieved a similar extent of reduction (AT 10 ± 6°, KT 11 ± 8°; p = 0.786). In follow-up a mean reduction loss of -5 ± 4° was seen. The technique had no influence on this (p = 0.998). The fracture morphology just managed to achieve a significant influence (p = 0.043). Low HU correlated significantly but weakly with lower extent of reduction (r = 0.241, p < 0.003) and greater reduction loss (r = 0.272, p < 0.001). In the age group 50-65 years 21% of men and 43% of women had bone quality of < 110 HU. Age and HU were significantly correlated (r = -0.701, p < 0.001).
CONCLUSION
The AT and KT are equivalent in terms of reduction and secure fixation properties. The high proportion of male and female patients with HU < 110 in the age group under 65 years and the influence on reduction and secure fixation emphasize the need for preoperative bone densitometry.
Topics: Aged; Female; Fracture Fixation, Internal; Humans; Lumbar Vertebrae; Male; Middle Aged; Pedicle Screws; Retrospective Studies; Spinal Fractures; Thoracic Vertebrae; Treatment Outcome
PubMed: 34110429
DOI: 10.1007/s00113-021-01013-7 -
Turkish Neurosurgery 2024To investigate the feasibility and safety of lumbar spinous process split laminotomy by quantitative anatomic analysis.
AIM
To investigate the feasibility and safety of lumbar spinous process split laminotomy by quantitative anatomic analysis.
MATERIAL AND METHODS
Nine fresh adult human cadaveric specimens (including 45 lumbar segments) were divided into 3 groups randomly. The simulated operations and anatomic measurements were performed to evaluate the visibility angle and surgical corridor at different retraction widths (8 mm, 10 mm, and 12 mm). By measuring the width causing bony fracture in 45 lumbar segments, the safety margin of retraction width was determined. The findings of lumbar spinous process split laminotomy in one typical case were presented.
RESULTS
At 8 mm retraction width, there was not enough surgical corridor for the operation procedures. At 10 mm and 12 mm retraction width, all operation procedures could be conducted smoothly. The 12 mm group presented a larger surgical corridor and shorter operative time compared with the 10 mm group. The imaging examination confirmed no bony fracture and articular capsule impairment. The visibility angle and exposure extent increased in proportion to the retraction width. The retraction width that resulted in the bony fracture ranged from 12.34 mm to 16.82 mm, with an average of (14.56 ± 1.73) mm. The positions of fracture were in the pedicle of the vertebral arch (68.9%), the lamina (26.7%), and the vertebral body (4.4%).
CONCLUSION
The retraction width of 10 mm-12 mm is safe and effective. The micromanipulations such as tumor resection, nervous exploration, dural suture, etc. can be conducted smoothly via the surgical corridor. In addition, the retraction width of 12.34~16.82 mm could serve as a safety margin for surgical planning. Our findings may provide a quantitative reference for clinical application of lumbar spinous process split laminotomy.
Topics: Adult; Humans; Laminectomy; Lumbar Vertebrae; Neurosurgical Procedures; Fractures, Bone; Lumbosacral Region
PubMed: 38497175
DOI: 10.5137/1019-5149.JTN.42396-22.2 -
The Journal of International Medical... Jun 2018Objective To study the clinical application of lumbar isthmus parameters in guiding pedicle screw placement. Methods Lumbar isthmus parameters were measured in normal...
Objective To study the clinical application of lumbar isthmus parameters in guiding pedicle screw placement. Methods Lumbar isthmus parameters were measured in normal lumbar x-rays and cadaveric specimens from a Chinese Han population. Distance between the medial pedicle border and lateral isthmus border was recorded as a 'D' value and was compared between X-rays and cadavers. Orthopaedic surgeons estimated different distances (2-6 mm) and angles (5-20°), and bias ratios between estimated and real values were compared. Orthopaedic residents placed pedicle screws on cadaveric specimens before and after application of the 'D' value, and screw placement accuracy was compared. Results Except for L4 vertebrae, significant differences in the 'D' value were found between 25 cadaveric specimens and x-ray films from 120 patients. Distances and angles estimated by 40 surgeons were significantly different from all real values, except 2 mm distance. Accuracy of pedicle screw placement by six orthopaedic residents was significantly improved by applying the 'D' value. Conclusions Surgeon estimates of distance were more accurate than angle estimates. Addition of a 'D' value to conventional parameters may significantly improve pedicle screw placement accuracy in lumbar spine surgery.
Topics: Adult; Cadaver; Female; Humans; Lumbar Vertebrae; Male; Pedicle Screws; Reproducibility of Results; Spinal Fusion
PubMed: 29619849
DOI: 10.1177/0300060518762986 -
Spinal Cord Series and Cases 2019Erdheim-Chester disease (ECD) is a rare, non-Langerhans cell histiocytosis. The clinical spectrum of ECD is diverse, varying from asymptomatic focal lesion to... (Review)
Review
INTRODUCTION
Erdheim-Chester disease (ECD) is a rare, non-Langerhans cell histiocytosis. The clinical spectrum of ECD is diverse, varying from asymptomatic focal lesion to life-threatening multisystem infiltration. Neurological manifestations of ECD are common, mostly due to the involvement of the central nerve system. However, spinal nerve or peripheral nerve involvement has rarely been mentioned.
CASE PRESENTATION
Herein, we present a case of a 32-year-old female patient complaining about radiating pain on the front and lateral side of her left thigh for 2 months. Spinal MRI with contrast enhancement showed a space-occupying lesion on the left L3/L4 intervertebral foramen, indicating an initial diagnosis of lumbar nerve schwannoma. The patient underwent surgery to remove the mass and decompress the lumbar nerve. Postoperative histological examination revealed the diffuse infiltration of foamy histiocytes that were CD68, CD163, and CD1a on immunostaining, which confirmed the diagnosis of Erdheim-Chester disease. The radiating pain was gradually alleviated and PET-CT was performed but showed no further involvement of ECD.
DISCUSSION
To the best of our knowledge, this is the first case of ECD demonstrated as an infiltrative mass on the spinal nerve, with imaging manifestations and compression symptoms similar to those of peripheral nerve schwannoma.
Topics: Adult; Diagnosis, Differential; Erdheim-Chester Disease; Female; Humans; Lumbar Vertebrae; Neurilemmoma; Spinal Nerves
PubMed: 31700688
DOI: 10.1038/s41394-019-0234-4 -
The Spine Journal : Official Journal of... Nov 2022The biomechanical impact of spondylophytes on segmental stiffness is largely unknown, despite their high incidence.
BACKGROUND CONTEXT
The biomechanical impact of spondylophytes on segmental stiffness is largely unknown, despite their high incidence.
PURPOSE
The aim of this study was to quantify the biomechanical contribution according to location and cranio-caudal extent of spondylophytes and to create a clinically applicable radiological classification system.
STUDY DESIGN
Biomechanical cadaveric study.
METHODS
Twenty-six cadaveric human lumbar spinal segments with spondylophytes were tested with a displacement-controlled stepwise reduction method. The reduction in load required for the same motion after spondylophyte dissection was used to calculate the biomechanical contribution in flexion, extension, axial rotation, lateral bending, anterior, posterior and lateral shear. The spondylophytes were categorized by assessment of their anatomical position and cranio-caudal extent in computed tomography images (grade 1: spondylophytes spanning less than 50% of the disc-height, grade 2:>50%, grade 3:>90%, grade 4: bony bridging between the vertebrae) by two experienced radiologists. Cohen's kappa (κ) was used to report interreader reliability.
RESULTS
The largest biomechanical effect of non-bridging spondylophytes (grade 1-3) was recorded during contralateral bending with a grade-dependent contribution of up to 35%. Other loading directions including ipsilateral bending and translational loading were affected with values below 13%. Spondylophytes with osseous bridging (grade 4) show large contribution to the segmental stiffness in most loading conditions with values reaching over 80%. Interreader agreement for the spondylophyte grading was "substantial" (κ=0.73, p<.001).
CONCLUSIONS
The location and cranio-caudal extent of spondylophytes are essential parameters for their biomechanical effect. A reproducible classification has been validated biomechanically and helps evaluate the effect of specific spondylophyte configurations on segmental stiffness.
CLINICAL SIGNIFICANCE
Non-bridging spondylophytes primarily act as tensile structures and do not provide relevant propping. A classification system is presented to support understanding of the biomechanical consequences of different spondylophyte configuration for clinical decision making in surgical planning.
Topics: Humans; Lumbar Vertebrae; Biomechanical Phenomena; Reproducibility of Results; Cadaver; Range of Motion, Articular
PubMed: 35671943
DOI: 10.1016/j.spinee.2022.06.001 -
European Spine Journal : Official... Oct 2013
Topics: Humans; Lumbar Vertebrae; Spinal Fractures; Thoracic Vertebrae
PubMed: 24113998
DOI: 10.1007/s00586-013-3062-4