Repair of pars interarticularis defect utilizing a pedicle and laminar screw construct: a new technique based on anatomical and biomechanical analysis

2012 ◽  
Vol 17 (1) ◽  
pp. 61-68 ◽  
Author(s):  
Rakesh D. Patel ◽  
Humberto G. Rosas ◽  
Michael P. Steinmetz ◽  
Paul A. Anderson
Keyword(s):  
Pedicle Screw ◽  
Spinal Canal ◽  
Biomechanical Analysis ◽  
Laminar Screw ◽  
Functional Spinal Unit ◽  
Significant Difference ◽  
Flexion Extension ◽  
Pars Interarticularis ◽  
Before And After ◽  
Biomechanical Tests

Object The theoretical advantage of pars interarticularis repair over spinal fusion to correct pars defects is that the treatment is a direct osteosynthesis that preserves motion at the involved functional spinal unit. Several techniques and constructs have been used to achieve greater rigidity, but these techniques may risk entry into the spinal canal, and adverse events are common. A pedicle and laminar screw construct placed entirely outside the spinal canal may offer greater stiffness and achieve higher pars defect healing rates. The purpose of this study was to biomechanically assess an intralaminar screw construct in cadaveric lumbar spines in comparison with other types of constructs typically used in pars repair and to quantify the sizes of screws that can be placed safely in both normal and spondylolytic vertebrae. Methods The L-4 and L-5 laminae in patients with spondylolysis and in controls who underwent CT (n = 41, each group) were measured by analysis of conventional axial CT images and multiplanar reformations constructed on a Vitrea workstation to determine the feasibility of translaminar fixation with a 4.5-mm-diameter screw. Biomechanical tests for torsion and flexion-extension were performed on 8 fresh human cadaveric lumbar spines before and after modeling for bilateral spondylolytic defects. Three pars repair techniques were tested at each level and in the following sequence: pedicle screw–cable, pedicle screw–rod–hook, and pedicle screw–intralaminar screw. Results The majority of laminae can accept 4.5 × 25-mm screws. The cable construct allowed the greatest motion and least stability across the defect in all biomechanical tests. The hook and laminar screw constructs performed similarly in all tests and exhibited no significant difference in stiffness. Conclusions A surgically placed intralaminar screw construct may be a safe and effective alternative to current pars repair methods.

In vitro biomechanical comparison of transpedicular versus translaminar C-2 screw fixation in C2–3 instrumentation

2007 ◽  
Vol 7 (4) ◽  
pp. 414-418 ◽  
Author(s):  
Chandan Reddy ◽  
Aditya V. Ingalhalikar ◽  
Scott Channon ◽  
Tae-Hong Lim ◽  
James Torner ◽  
...  
Keyword(s):  
Pedicle Screw ◽  
Pedicle Screws ◽  
Upper Cervical Spine ◽  
Lateral Mass ◽  
C2 Pedicle Screw ◽  
Laminar Screw ◽  
Significant Difference ◽  
Flexion Extension ◽  
C2 Laminar Screw

Object In instrumentation of the upper cervical spine, placement of pedicle screws into C-2 is generally safe, although there is the potential for injury to the vertebral arteries. Owing to this risk, translaminar screws into C-2 have been used. The aim of this study was to compare the stability of the in vitro cadaveric spine using C-2 laminar compared with C-2 pedicle screws in C2–3 instrumentation. Methods Eight fresh frozen human cadaveric cervical spines (C1–6) were potted at C1–2 and C5–6. Pure moments in increments of 0.3 Nm to a maximum of 1.5 Nm were applied in flexion, extension, right and left lateral bending, and right and left axial rotation. Each specimen was tested sequentially in three modes: 1) intact; 2) C2 pedicle screw–C3 lateral mass fixation; and 3) C2 laminar screw–C3 lateral mass fixation. The sequence of fixation testing was randomized. Motion was tracked with reflective markers attached to C-2 and C-3. Results Spinal levels with instrumentation showed significantly less motion than the intact spine in all directions and with all loads greater than 0.3 Nm (p < 0.05). Although there was no significant difference between C2 pedicle screw–C3 lateral mass fixation and C2 laminar screw–C3 lateral mass fixation, generally the former type of fixation was associated with less motion than the latter. Conclusions When pedicle screws in C-2 are contraindicated or inappropriate, laminar screws in C-2 offer a safe and acceptable option for posterior instrumentation.

scholarly journals Biomechanical Evaluation of Cortical Bone Trajectory Fixation with Traditional Pedicle Screw in the Lumbar Spine: A Finite Element Study

2021 ◽  
Vol 11 (22) ◽  
pp. 10583
Author(s):  
Kuo-Chih Su ◽  
Kun-Hui Chen ◽  
Chien-Chou Pan ◽  
Cheng-Hung Lee
Keyword(s):  
Finite Element ◽  
Lumbar Spine ◽  
Cortical Bone ◽  
Pedicle Screw ◽  
Spinal Surgery ◽  
Pedicle Screws ◽  
Element Model ◽  
Cortical Bone Trajectory ◽  
Significant Difference ◽  
Flexion Extension

Cortical bone trajectory (CBT) is increasingly used in spinal surgery. Although there are many biomechanical studies, the biomechanical effect of CBT in combination with traditional pedicle screws is not detailed. Therefore, the purpose of this study was to investigate the effects of the traditional pedicle screw and CBT screw implantation on the lumbar spine using finite element methods. Based on the combination of the traditional pedicle screw and the CBT system implanted into the lumbar spine, four finite element spinal lumbar models were established. The models were given four different load conditions (flexion, extension, lateral bending, and axial rotation), and the deformation and stress distribution on the finite element model were observed. The results show that there was no significant difference in the structural stability of the lumbar spine model between the traditional pedicle screw system and the CBT system. In addition, CBT may reduce stress on the endplate. Different movements performed by the model may have significant biomechanical effects on the spine and screw system. Clinical spinal surgeons may also consider using the CBT system in revision spinal surgery, which may contribute to smaller wounds.

A Study to Compare the Efficacy of a Biodegradable Dynamic Fixation System With Titanium Devices in Posterior Spinal Fusion Between Articular Processes in a Canine Model

2020 ◽  
Vol 143 (3) ◽  
Author(s):  
Tailong Yu ◽  
Leyu Zheng ◽  
Guanghua Chen ◽  
Nanxiang Wang ◽  
Xiaoyan Wang ◽  
...  
Keyword(s):  
Lumbar Fusion ◽  
Biomechanical Analysis ◽  
Adjacent Segment ◽  
Rigid Fixation ◽  
Initial Shape ◽  
Posterior Lumbar Fusion ◽  
Dynamic Fixation ◽  
Flexion Extension ◽  
Biomechanical Tests ◽  
Fixation System

Abstract The objective of this study was to apply a biodegradable dynamic fixation system (BDFS) for lumbar fusion between articular processes and compare the fusion results and biomechanical changes with those of conventional rigid fixation. Twenty-four mongrel dogs were randomly assigned to 2 groups and subjected to either posterior lumbar fusion surgery with a BDFS or titanium rods (TRs) at the L5–L6 segments. Six animals in each group were sacrificed at 8 or 16 weeks. Fusion conditions were evaluated by computed tomography (CT), manual palpation, biomechanical tests, and histological analysis. Biomechanical tests were performed at the L4–7 (for range of motion (ROM)) and L5–6 (for fusion stiffness) segments. Histological examination was performed on organs, surrounding tissues, and the fused area. The magnesium alloy components maintained their initial shape 8 weeks after the operation, but the meshing teeth were almost completely degraded at 16 weeks. The biomechanical analysis revealed an increased lateral bending ROM at 8 weeks and axial torsion ROM at 16 weeks. The L4–5 extension–flexion ROMs in the BDFS group were 2.29 ± 0.86 deg and 3.17 ± 1.08 deg at 16 weeks, respectively, compared with 3.22 ± 0.56 deg and 5.55 ± 1.84 deg in TR group. However, both groups showed similar fusion results. The BDFS design is suitable, and its degradation in vivo is safe. The BDFS can be applied for posterior lumbar fusion between articular processes to complete the fusion well. Additionally, the BDFS can reduce the decline in lateral motion and hypermotion of the cranial adjacent segment in flexion–extension motion.

Pin Insertion to the Interosseous Hood Minimize the Finger Motion Restriction for the Proximal Phalangeal Percutaneous Fixation: A Cadaveric Study

2020 ◽  
Vol 25 (02) ◽  
pp. 177-183
Author(s):  
Akira Ikumi ◽  
Toshikazu Tanaka ◽  
Yusuke Matsuura ◽  
Kazuki Kuniyoshi ◽  
Takane Suzuki ◽  
...  
Keyword(s):  
Soft Tissues ◽  
Insertion Point ◽  
Lateral Band ◽  
Significant Difference ◽  
Flexion Extension ◽  
Before And After ◽  
Pip Joint ◽  
Fresh Frozen ◽  
Joint Flexion ◽  
Finger Motion

Background: The purpose of this study was to identify the optimal pin insertion point to minimize finger motion restriction for proximal phalangeal fixation in cadaver models. Methods: We used 16 fingers from three fresh-frozen cadavers (age, 82–86 years). Each finger was dissected at the level of the carpometacarpal joint and fixated to a custom-built range of motion (ROM)-measuring apparatus after skin removal. The pin was inserted into the bone through four gliding soft tissues: the interosseous hood, dorsal capsule, lateral band, and sagittal band. Then, each tendon was pulled by a prescribed weight in three finger positions (flexion, extension, and intrinsic plus position). Changes in the metacarpophalangeal (MCP), proximal interphalangeal (PIP), and distal interphalangeal (DIP) angles were measured before and after pinning. We compared the differences between the insertion points using the Tukey-Kramer post hoc test. Results: Placement of pins into the sagittal band significantly restricted MCP joint flexion, while placement into the dorsal capsule and lateral band significantly restricted PIP joint flexion. Only placement into the interosseous hood showed no significant difference in joint angles between the three finger positions compared to pre-pin insertion. There were no significant effects on MCP, PIP, and DIP joint extension. Conclusions: The ROM of the MCP joint was obstructed due to pinning in most areas of insertion. However, pin insertion to the interosseous hood did not obstruct the finger flexion ROM compared to that of other gliding soft tissues; therefore, we believe that the interosseous hood may be a suitable pin insertion point for proximal phalangeal fixation.

Pyrocardan Scaphotrapeziotrapezoid Joint Arthroplasty for Isolated Osteoarthritis: Results after a Mean Follow-Up of 5 Years

2021 ◽  
Author(s):  
Martin Cholley-Roulleau ◽  
Yves Bouju ◽  
Flore-Anne Lecoq ◽  
Alexandre Fournier ◽  
Philippe Bellemère
Keyword(s):  
Case Series ◽  
Preoperative Assessment ◽  
Contralateral Side ◽  
High Rate ◽  
Significant Difference ◽  
Flexion Extension ◽  
Functional Scores ◽  
Before And After ◽  
The Mean

Abstract Background Isolated scaphotrapeziotrapezoid (STT) osteoarthritis (OA) mainly develops in women over 50 years of age in a bilateral manner. Many surgical treatments are available, including distal scaphoid resection with or without interposition, trapeziectomy, and STT arthrodesis. However, there is a controversy about which procedure is the most effective. Purposes The purpose of this study was to report the outcomes of the Pyrocardan implant for treating STT isolated OA at a mean follow-up of 5 years. Patients and Methods Consecutive patients who underwent STT arthroplasty using the Pyrocardan were reviewed retrospectively by an independent examiner who performed a clinical and radiological evaluation. Results The mean follow-up time was 5 years (range 3–8 years). Thirteen patients (76%) were followed for more than 5 years. Between the preoperative assessment and the last follow-up, pain levels decreased significantly. There was no significant difference in the mean Kapandji opposition score. Grip and pinch strengths were 88 and 91% of the contralateral side. The active range of motion in flexion–extension and radioulnar deviation was not significantly different to the contralateral side (119° vs. 121° and 58° vs. 52°, p > 0.1). Functional scores were improved significantly. No identifiable differences were found in the radioscaphoid, capitolunate, and scapholunate angles before and after surgery. In three cases, the preoperative dorsal intercalated scapholunate instability (DISI) failed to be corrected. In one case, DISI appeared after the procedure. There was one asymptomatic dislocation of the implant. Calcification around the trapezium and/or distal scaphoid was found in four cases. The survival rate of the implant without reoperation was 95%. Conclusions In the medium term, Pyrocardan implant is an effective treatment for STT OA as it reduces pain, increases grip strength, and maintains wrist mobility. This is consistent with the results of other published case series using pyrocarbon implants. It provides a high rate of patient satisfaction. Nevertheless, the surgical procedure must be done carefully to avoid STT ligament damage, periarticular calcifications, or dislocation.

scholarly journals Biomechanical Analysis of a Growing Rod with Sliding Pedicle Screw System for Early-Onset Scoliosis

2019 ◽  
Vol 2019 ◽  
pp. 1-7
Author(s):  
Zhihua Ouyang ◽  
Wenjun Wang ◽  
Nicholas Vaudreuil ◽  
Robert Tisherman ◽  
Yiguo Yan ◽  
...  
Keyword(s):  
Range Of Motion ◽  
Pedicle Screw ◽  
Early Onset ◽  
Early Onset Scoliosis ◽  
Biomechanical Analysis ◽  
Apical Segment ◽  
Fusion Technique ◽  
Fixed Group ◽  
Growing Rod ◽  
Flexion Extension

Early-onset scoliosis (EOS) remains a challenging condition for which current nonfusion surgeries require iterative lengthening surgeries. A growing rod with sliding pedicle screw system (GRSPSS) was developed to treat spinal deformities without repeated operative lengthening. This study was performed to evaluate whether GRSPSS had similar stability as a conventional pedicle screw system to maintain deformity correction. A serial-linkage robotic manipulator with a six-axis load cell positioned on the end-effector was utilized to evaluate the mechanical stability of the GRSPSS versus conventional fixed scoliosis instrumentation. Ten skeletally mature thoracic female Katahdin sheep spines (T4-L1) were subjected to 2.5 Nm of flexion-extension (FE), lateral bending (LB), and axial rotation (AR) in 2° increments for each state. The overall range of motion (ROM), apical segment ROM, and stiffness were calculated and reported. A two-tailed paired t-test was used to detect significant differences (p<0.05) between the fixed group and GRSPSS fixation. There were no significant differences in overall range of motion (ROM), apical segment ROM, or stiffness for FE or LB between the GRSPSS group and fixed group. In AR, the GRSPSS group showed increased ROM compared to the fixed group for the overall spine (36.0° versus 19.2°, p<0.01) and for the instrumented T8-T10 segments (7.0° versus 2.9°, p=0.02). Similarly, the fixed rod elastic zone (EZ) stiffness was significantly greater than the GRSPSS EZ stiffness (0.29 N/m versus 0.17 N/m, p<0.001). The space around the rod allows for the increased AR observed with the GRSPSS fusion technique and is necessary for axial growth. The GRSPSS fusion model shows equivalent flexion and LB stability to current fusion models and represents a stable fusion technique and may allow for longitudinal growth during childhood.

scholarly journals Use of an inertial measurement unit sensor in pedicle screw placement improves trajectory accuracy

PLoS ONE ◽  
2020 ◽  
Vol 15 (11) ◽  
pp. e0242512
Author(s):  
Satoshi Baba ◽  
Kenichi Kawaguchi ◽  
Kazuhito Itamoto ◽  
Takeshi Watanabe ◽  
Mitsumasa Hayashida ◽  
...  
Keyword(s):  
Pedicle Screw ◽  
Inertial Measurement Unit ◽  
Low Cost ◽  
Measurement Unit ◽  
Rotational Angle ◽  
Inertial Measurement ◽  
Computed Tomography Images ◽  
Freehand Technique ◽  
Significant Difference ◽  
Before And After

Ascertaining the accuracy of the pedicle screw (PS) trajectories is important as PS malpositioning can cause critical complications. We aimed to determine the angle range over which estimation is unreliable; build a low-cost PS placement support system that uses an inertial measurement unit (IMU) to enable the monitoring of surgical tools and PS trajectories, and determine the situations where IMU support would be most beneficial. In PS insertion experiments, we used cadaver samples that included lumbar porcine spines. Computed tomography images obtained before and after PS insertion were viewed. Offsets between the planned and implanted PS trajectories in the freehand and IMU-assisted groups were analyzed. The PS cortical bone breaches were classified according to the Gertzbein and Robbins criteria (GRC). Added head-down tilted sample experiments were repeated wherein we expected a decreased rostro-caudal rotational accuracy of the PS according to the angle estimation ability results. Evaluation of the PS trajectory accuracy revealed no significant advantage of IMU-assisted rostro-caudal rotational accuracy versus freehand accuracy. According to the GRC, IMU assistance significantly increased the rate of clinically acceptable PS positions (RoCA) than the freehand technique. In the head-down tilted sample experiments, IMU assist provided increased accuracies with both rostro-caudal and medial rotational techniques when compared with the freehand technique. In the freehand group, RoCA was significantly decreased in samples with rostral tilting relative to that in the samples without. However, In the IMU-assisted group, no significant difference in RoCA between the samples with and without head-down tilting was observed. Even when the planned PS medial and/or rostro-caudal rotational angle was relatively large and difficult to reproduce manually, IMU-support helped maintain the PS trajectory accuracy and positioning safety. IMU assist in PS placement was more beneficial, especially for larger rostro-caudal and/or medial rotational pedicle angles.

scholarly journals Biomechanical analysis of occipitocervical stabilization techniques: emphasis on integrity of osseous structures at the occipital implantation sites

2020 ◽  
Vol 33 (2) ◽  
pp. 138-147
Author(s):  
Bryan W. Cunningham ◽  
Kyle B. Mueller ◽  
Kenneth P. Mullinix ◽  
Xiaolei Sun ◽  
Faheem A. Sandhu
Keyword(s):  
Fatigue Testing ◽  
Plate Fixation ◽  
Axial Rotation ◽  
Biomechanical Analysis ◽  
Lateral Bending ◽  
Mineral Density ◽  
Plate Group ◽  
Significant Difference ◽  
Flexion Extension ◽  
Implantation Sites

OBJECTIVEThe objective of the current study was to quantify and compare the multidirectional flexibility properties of occipital anchor fixation with conventional methods of occipitocervical screw fixation using nondestructive and destructive investigative methods.METHODSFourteen cadaveric occipitocervical specimens (Oc–T2) were randomized to reconstruction with occipital anchors or an occipital plate and screws. Using a 6-degree-of-freedom spine simulator with moments of ± 2.0 Nm, initial multidirectional flexibility analysis of the intact and reconstructed conditions was performed followed by fatigue loading of 25,000 cycles of flexion-extension (x-axis, ± 2.0 Nm), 15,000 cycles of lateral bending (z-axis, ± 2.0 Nm), and 10,000 cycles of axial rotation (y-axis, ± 2.0 Nm). Fluoroscopic images of the implantation sites were obtained before and after fatigue testing and placed on an x-y coordinate system to quantify positional stability of the anchors and screws used for reconstruction and effect, if any, of the fatigue component. Destructive testing included an anterior flexural load to construct failure. Quantification of implant, occipitocervical, and atlantoaxial junction range of motion is reported as absolute values, and peak flexural failure moment in Newton-meters (Nm).RESULTSAbsolute value comparisons between the intact condition and 2 reconstruction groups demonstrated significant reductions in segmental flexion-extension, lateral bending, and axial rotation motion at the Oc–C1 and C1–2 junctions (p < 0.05). The average bone mineral density at the midline keel (1.422 g/cm3) was significantly higher compared with the lateral occipital region at 0.671 g/cm3 (p < 0.05). There were no significant differences between the occipital anchor and plate treatments in terms of angular rotation (degrees; p = 0.150) or x-axis displacement (mm; p = 0.572), but there was a statistically significant difference in y-axis displacement (p = 0.031) based on quantitative analysis of the pre- and postfatigue fluoroscopic images (p > 0.05). Under destructive anterior flexural loading, the occipital anchor group failed at 90 ± 31 Nm, and the occipital plate group failed at 79 ± 25 Nm (p > 0.05).CONCLUSIONSBoth reconstructions reduced flexion-extension, lateral bending, and axial rotation at the occipitocervical and atlantoaxial junctions, as expected. Flexural load to failure did not differ significantly between the 2 treatment groups despite occipital anchors using a compression-fit mechanism to provide fixation in less dense bone. These data suggest that an occipital anchor technique serves as a biomechanically viable clinical alternative to occipital plate fixation.

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