A biomechanical study on the effect of lengthening magnitude on spine off-loading in magnetically controlled growing rod surgery: Implications on lengthening frequency

Purpose: To assess whether the magnitude of lengthening in magnetically controlled growing rod (MCGR) surgeries has an immediate or delayed effect on spinal off-loading. Methods: 9 whole porcine spines were instrumented using two standard MCGRs from T9 to L5. Static compression testing using a mechanical testing system (MTS) was performed at three MCGR lengthening stages (0 mm, 2 mm, and 6 mm) in each spine. At each stage, five cycles of compression at 175N with 25 min of relaxation was carried out. Off-loading was derived by comparing the load sustained by the spine with force applied by the MTS to the spine. Micro-CT imaging was subsequently performed. Results: The mean load sustained by the vertebral body before lengthening was 39.69N, and immediately after lengthening was 25.12N and 19.91N at 2 mm and 6 mm lengthening, respectively; decreasing to 10.07N, 8.31N, and 8.17N after 25 minutes of relaxation, at 0 mm, 2 mm, and 6 mm lengthening stages, respectively. There was no significant difference in off-loading between 2 mm and 6 mm lengthening stages, either instantaneously ( p = 0.395) or after viscoelastic relaxation ( p = 0.958). CT images showed fractures/separations at the level of pedicle screws in six spines and in the vertebral body’s growth zone in five spines after 6 mm MCGR lengthening. Conclusion: This study demonstrated MCGRs cause significant off-loading of the spine leading to stress shielding. 6 mm of lengthening caused tissue damage and microfractures in some spines. There was no significant difference in spine off-loading between 2 mm and 6 mm MCGR lengthening, either immediately after lengthening or after viscoelastic relaxation.

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Effect of lumbar total disc arthroplasty on the segmental motion and intradiscal pressure at the adjacent level: an in vitro biomechanical study

Journal of Neurosurgery Spine ◽

10.3171/2009.7.spine094 ◽

2009 ◽

Vol 11 (6) ◽

pp. 715-723 ◽

Cited By ~ 19

Author(s):

Aditya V. Ingalhalikar ◽

Chandan G. Reddy ◽

Tae Hong Lim ◽

James C. Torner ◽

Patrick W. Hitchon

Keyword(s):

Pedicle Screws ◽

Biomechanical Study ◽

Intradiscal Pressure ◽

Segmental Motion ◽

Artificial Disc ◽

Lateral Bending ◽

Adjacent Level ◽

Disc Disease ◽

Significant Difference ◽

Ps Condition

Object The artificial disc has been proposed as an alternative to spinal fusion for degenerative disc disease. The primary aim of this biomechanical study was to compare motion and intradiscal pressure (IDP) in a ball-and-socket artificial disc–implanted cadaveric lumbar spine, at the operative and adjacent levels, using a displacement-controlled setup. A secondary comparison involved a “salvage” construct, consisting of pedicle screws (PSs) added in supplementation to the artificial disc construct. Methods Ten human cadaveric lumbosacral spines (L2–S1) were potted at L-2 and S-1. All measurements were initially made in the intact spine, followed by implantation of the artificial disc, and finally by the salvage PS condition. For the artificial disc condition, a Maverick ball-and-socket artificial disc was implanted at L4–5. For the PS condition, CD Horizon PSs were placed at L4–5, and the artificial disc was left in place. A displacement-controlled, custom-designed testing apparatus was used to impart motion in the sagittal and coronal planes. Motion at both the implanted level (L4–5) and immediately adjacent levels (L3–4 and L5–S1) was measured. Intradiscal pressure at the rostral adjacent level (L3–4) was also measured. The Tukey test was used for statistical analysis (p < 0.05). Results In flexion, no significant difference was noted between the artificial disc and the intact spine with regard to motion at the operative level, motion at adjacent levels, or IDP. In lateral bending, while the artificial disc significantly decreased operative-level motion (p < 0.05), no significant difference was noted in adjacent-level motion or IDP. With regard to extension, the artificial disc significantly increased operative level motion and decreased the rostral adjacent level (L3–4) motion and IDP (p < 0.05). Caudal adjacent-level (L5–S1) motion was not significantly different. In flexion and lateral bending, the addition of PSs significantly decreased motion at the implanted level when compared with the intact spine and the artificial disc (p < 0.05). This decrease in motion at the index level was associated with a compensatory increase in motion at both adjacent levels in flexion only (p < 0.05), but not in lateral bending (p > 0.05). The IDP was significantly increased in lateral bending but not in flexion. With regard to extension, the significant decrease in IDP that was noted with the artificial disc persisted despite the addition of PSs (p < 0.05). Conclusions The artificial disc either maintains or reduces adjacent-level motion and pressure, compared with the intact spine. The addition of PSs to the artificial disc construct leads to significantly increased motion at adjacent levels in flexion and significantly increased IDP in lateral bending. At the operative level, the artificial disc is associated with hypermobility in extension, which is restored to the intact state after the addition of supplementary PSs.

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Interference Screw Versus Suture Anchors for Femoral Fixation in Medial Patellofemoral Ligament Reconstruction: A Biomechanical Study

Orthopaedic Journal of Sports Medicine ◽

10.1177/2325967121989282 ◽

2021 ◽

Vol 9 (3) ◽

pp. 232596712198928

Author(s):

Heath P. Gould ◽

Nicholas R. Delaney ◽

Brent G. Parks ◽

Roshan T. Melvani ◽

Richard Y. Hinton

Keyword(s):

Medial Patellofemoral Ligament ◽

Interference Screw ◽

Biomechanical Study ◽

Graft Fixation ◽

Mpfl Reconstruction ◽

Suture Anchors ◽

Femoral Fixation ◽

Significant Difference ◽

Load To Failure ◽

The Mean

Background: Femoral-sided graft fixation in medial patellofemoral ligament (MPFL) reconstruction is commonly performed using an interference screw (IS). However, the IS method is associated with several clinical disadvantages that may be ameliorated by the use of suture anchors (SAs) for femoral fixation. Purpose: To compare the load to failure and stiffness of SAs versus an IS for the femoral fixation of a semitendinosus autograft in MPFL reconstruction. Study Design: Controlled laboratory study. Methods: Based on a priori power analysis, a total of 6 matched pairs of cadaveric knees were included. Specimens in each pair were randomly assigned to receive either SA or IS fixation. After an appropriate reconstruction procedure, the looped end of the MPFL graft was pulled laterally at a rate of 6 mm/s until construct failure. The best-fit slope of the load-displacement curve was then used to calculate the stiffness (N/mm) in a post hoc fashion. A paired t test was used to compare the mean load to failure and the mean stiffness between groups. Results: No significant difference in load to failure was observed between the IS and the SA fixation groups (294.0 ± 61.1 vs 250.0 ± 55.9; P = .352), although the mean stiffness was significantly higher in IS specimens (34.5 ± 9.6 vs 14.7 ± 1.2; P = .004). All IS reconstructions failed by graft pullout from the femoral tunnel, whereas 5 of the 6 SA reconstructions failed by anchor pullout. Conclusion: In this biomechanical study using a cadaveric model of MPFL reconstruction, SA femoral fixation was not significantly different from IS fixation in terms of load to failure. The mean load-to-failure values for both reconstruction techniques were greater than the literature-reported values for the native MPFL. Clinical Relevance: These results suggest that SAs are a biomechanically viable alternative for femoral-sided graft fixation in MPFL reconstruction.

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Level of Experience Does Not Influence the Accuracy of Radiographic and Ultrasound Measurements of Magnetically Controlled Growing Rod Distractions

Journal of Pediatric Orthopaedics ◽

10.1097/bpo.0000000000001449 ◽

2020 ◽

Vol 40 (5) ◽

pp. e341-e345

Author(s):

Brian Bye ◽

Chelsea K. Graham ◽

Christopher Robbins ◽

Nicholas Wallace ◽

Benjamin Lindsey ◽

...

Keyword(s):

Growing Rod ◽

Ultrasound Measurements ◽

Magnetically Controlled Growing Rod ◽

Level Of Experience

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A COMPARATIVE BIOMECHANICAL STUDY OF THE LOOPED SQUARE SLIP KNOT AND THE SIMPLE SURGICAL KNOT

Hand Surgery ◽

10.1142/s0218810406003152 ◽

2006 ◽

Vol 11 (01n02) ◽

pp. 93-99 ◽

Cited By ~ 1

Author(s):

Surut Jianmongkol ◽

Geoffrey Hooper ◽

Weerachai Kowsuwon ◽

Tala Thammaroj

Keyword(s):

Ultimate Strength ◽

Hand Surgery ◽

Biomechanical Properties ◽

Biomechanical Study ◽

Skin Closure ◽

Significant Difference ◽

Mode Of Failure ◽

Repetitive Loading ◽

Slip Knot

The looped square slip knot was introduced as a technique for skin closure to avoid the use of sharp instruments in suture removal after hand surgery. We compared the biomechanical properties of this knot with the simple surgical square knot. The ultimate strength of the looped square slip knot was significantly (p = 0.015) higher than the simple surgical knot. There was no significant difference between the two knots in mode of failure. Knot slippage or suture breakage did not occur in any samples when testing security by repetitive loading. Therefore, the looped square slip knot is a safe and convenient alternative to the two-throw surgical knot for use in hand surgery.

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Cortical Bone Trajectory Screws in Posterior Lumbar Interbody Fusion: Minimally Invasive Surgery for Maximal Muscle Sparing—A Prospective Comparative Study with the Traditional Open Technique

BioMed Research International ◽

10.1155/2018/7424568 ◽

2018 ◽

Vol 2018 ◽

pp. 1-7 ◽

Cited By ~ 14

Author(s):

Nicola Marengo ◽

Marco Ajello ◽

Michele Federico Pecoraro ◽

Giulia Pilloni ◽

Giovanni Vercelli ◽

...

Keyword(s):

Comparative Study ◽

Interbody Fusion ◽

Pedicle Screws ◽

Posterior Lumbar Interbody Fusion ◽

Fusion Rate ◽

Lumbar Interbody Fusion ◽

Significant Difference ◽

Prospective Comparative Study ◽

One Year ◽

Muscular Damage

Introduction. A prospective comparative study between classical posterior interbody fusion with peduncular screws and the new technique with divergent cortical screws was conducted. Material and Methods. Only patients with monosegmental degenerative disease were recruited into this study. We analyzed a cohort of 40 patients treated from January 2015 to March 2016 divided into 2 groups (20 patients went to traditional open surgery and 20 patients under mini-invasive strategy). Primary endpoints of this study are fusion rate and muscular damage; secondary endpoints analyzed were three different clinical scores (ODI, VAS, and EQ) and the morbidity rate of both techniques. Results. There was no significant difference in fusion rate between the two techniques. In addition, a significant difference in muscular damage was found according to the MRI evaluation. Clinical outcomes, based on pain intensity, Oswestry Disability Index status, and Euroquality-5D score, were found to be also statistically different, even one year after surgery. This study also demonstrated a correlation between patients’ muscular damage and their clinical outcome. Conclusions. Cortical bone trajectory screws would provide similar outcomes compared to pedicle screws in posterior lumbar interbody fusion at one year after surgery, and this technique represents a reasonable alternative to pedicle screws.

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Is It Necessary to Reduce Thoracolumbar Compression Fractures with Intermediate Screws in the Fractured Vertebra?

10.21203/rs.3.rs-542387/v1 ◽

2021 ◽

Author(s):

ZeJun Xing ◽

Shuai Hao ◽

XiaoFei Wu

Keyword(s):

Blood Loss ◽

Body Height ◽

Pedicle Screws ◽

Operation Time ◽

Short Segment ◽

Compression Fractures ◽

Significant Difference ◽

Before And After ◽

Screw Group

Abstract PurposeTo compare the efficacy and safety of percutaneous short-segment pedicle screws fixation (PPSF) with or without intermediate screws (IS) for the treatment of thoracolumbar compression fractures.MethodsFrom January 2016 to March 2019, a retrospective study of 38 patients with thoracolumbar compression fractures conducted. The patients were divided into a 4-screw group (without IS) and a 6-screw group (with IS) according to whether pedicle screws were placed in the fractured vertebrae. Combined positional reduction effects with the technique of pre-contoured lordotic rods were used to reduce the fracture by lengthening the anterior column of the fractured vertebrae. The posterior structure of the fractured vertebrae was undertaken as the fulcrum point for both groups. The operation time, intra-operative blood loss, visual analogue scale (VAS), anterior vertebral body height (AVBH), segment kyphosis（SK）before and after operation and complications were recorded.ResultsAlthough the operation time and blood loss in the 6-screw group were higher than in the 4-screw group, difference was not significant (P＞0.05). There was no significant difference in VAS, AVBH and SK between the two groups (P＞0.05). Nevertheless, these results were significant differences between the preoperative and the immediate postoperative, between preoperative and follow-up groups (P < 0.001). No neurologic injury was observed in either groups. ConclusionsIn the treatment of thoracolumbar compression fractures, percutaneous short-segment pedicle screws fixation without intermediate screws in the 4-screw construct may obtain the same clinical effect as that in the 6-screw construct.

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The Peroneal Groove Deepening Procedure: A Biomechanical Study of Pressure Reduction

Foot & Ankle International ◽

10.1177/107110070502600603 ◽

2005 ◽

Vol 26 (6) ◽

pp. 442-448 ◽

Cited By ~ 32

Author(s):

Craig I. Title ◽

Hung-Geun Jung ◽

Brent G. Parks ◽

Lew C. Schon

Keyword(s):

Biomechanical Study ◽

Posterior Tibial Tendon ◽

Peroneal Tendon ◽

Foot And Ankle ◽

Calcaneofibular Ligament ◽

Significant Difference ◽

Mean Pressure ◽

Fresh Frozen ◽

The Mean ◽

Pressure Changes

Background: The goal of this study was to identify pressure changes throughout the peroneal groove after a groove deepening procedure. We hypothesized that pressures would decrease. Methods: Twelve fresh-frozen foot and ankle specimens were used. A thin pressure strip containing four sensor pads was secured within the peroneal groove with pads 1 through 4 positioned at the calcaneofibular ligament (CFL) and at the distal, middle, and proximal groove, respectively. The midstance phase of gait was simulated with loads applied to the plantar foot and posterior tibial tendon and to the peroneus longus and brevis tendons. Pressures were recorded with the ankle in neutral, plantarflexion, dorsiflexion, inversion, and eversion. Groove deepening was done by osteotomizing the posterior fibular wall. Pressure readings were then recorded. Average pressures for each of the four sensor pads after the procedure were compared to those obtained before the procedure. Results: The mean pressure overlying the CFL increased at all five ankle positions; however, these changes were not significant. Significant decreases in pressure were noted within the distal and middle groove at all ankle positions after the peroneal groove deepening procedure. Pressure within the proximal groove increased at all but one position, with a significant difference noted in neutral and plantarflexion. Conclusion: Pressures within the middle and distal peroneal groove significantly decreased after a groove deepening procedure. Combining this technique with peroneal tendon debridement may be advantageous for treatment of partial peroneal tendon tears or recalcitrant peroneal tendinitis.

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