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Mao Y, Patel AA, Meade S, Benzel E, Steinmetz MP, Mroz T, Habboub G. Review of mechanisms of expandable spine surgery devices. Expert Rev Med Devices 2024; 21:381-390. [PMID: 38557229 DOI: 10.1080/17434440.2024.2337295] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2024] [Accepted: 03/27/2024] [Indexed: 04/04/2024]
Abstract
INTRODUCTION Expandable devices such as interbody cages, vertebral body reconstruction cages, and intravertebral body expansion devices are frequently utilized in spine surgery. Since the introduction of expandable implants in the early 2000s, the variety of mechanisms that drive expansion and implant materials have steadily increased. By examining expandable devices that have achieved commercial success and exploring emerging innovations, we aim to offer an in-depth evaluation of the different types of expandable cages used in spine surgery and the underlying mechanisms that drive their functionality. AREAS COVERED We performed a review of expandable spinal implants and devices by querying the National Library of Medicine MEDLINE database and Google Patents database from 1933 to 2024. Five major types of mechanical jacks that drive expansion were identified: scissor, pneumatic, screw, ratchet, and insertion-expansion. EXPERT OPINION We identified a trend of screw jack mechanism being the predominant machinery in vertebral body reconstruction cages and scissor jack mechanism predominating in interbody cages. Pneumatic jacks were most commonly found in kyphoplasty devices. Critically reviewing the mechanisms of expansion and identifying trends among effective and successful cages allows both surgeons and medical device companies to properly identify future areas of development.
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Affiliation(s)
- Yuncong Mao
- Center for Spine Health, Cleveland Clinic Foundation, Cleveland Clinic Lerner College of Medicine, Cleveland, OH, USA
| | - Arpan A Patel
- Department of Neurosurgery, Cleveland Clinic Foundation, Cleveland Clinic Lerner College of Medicine, Cleveland, OH, USA
| | - Seth Meade
- Case Western Reserve University School of Medicine, Cleveland, OH, USA
| | - Edward Benzel
- Center for Spine Health, Cleveland Clinic Foundation, Cleveland Clinic Lerner College of Medicine, Cleveland, OH, USA
- Department of Neurosurgery, Cleveland Clinic Foundation, Cleveland Clinic Lerner College of Medicine, Cleveland, OH, USA
| | - Michael P Steinmetz
- Center for Spine Health, Cleveland Clinic Foundation, Cleveland Clinic Lerner College of Medicine, Cleveland, OH, USA
- Department of Neurosurgery, Cleveland Clinic Foundation, Cleveland Clinic Lerner College of Medicine, Cleveland, OH, USA
| | - Thomas Mroz
- Center for Spine Health, Cleveland Clinic Foundation, Cleveland Clinic Lerner College of Medicine, Cleveland, OH, USA
- Department of Neurosurgery, Cleveland Clinic Foundation, Cleveland Clinic Lerner College of Medicine, Cleveland, OH, USA
| | - Ghaith Habboub
- Center for Spine Health, Cleveland Clinic Foundation, Cleveland Clinic Lerner College of Medicine, Cleveland, OH, USA
- Department of Neurosurgery, Cleveland Clinic Foundation, Cleveland Clinic Lerner College of Medicine, Cleveland, OH, USA
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Biomechanical and clinical studies on lumbar spine fusion surgery: a review. Med Biol Eng Comput 2023; 61:617-634. [PMID: 36598676 DOI: 10.1007/s11517-022-02750-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2022] [Accepted: 12/22/2022] [Indexed: 01/05/2023]
Abstract
Low back pain is associated with degenerative disc diseases of the spine. Surgical treatment includes fusion and non-fusion types. The gold standard is fusion surgery, wherein the affected vertebral segment is fused. The common complication of fusion surgery is adjacent segment degeneration (ASD). The ASD often leads to revision surgery, calling for a further fusion of adjacent segments. The existing designs of nonfusion type implants are associated with clinical problems such as subsidence, difficulty in implantation, and the requirement of revision surgeries. Various surgical approaches have been adopted by the surgeons to insert the spinal implants into the affected segment. Over the years, extensive biomechanical investigations have been reported on various surgical approaches and prostheses to predict the outcomes of lumbar spine implantations. Computer models have been proven to be very effective in identifying the best prosthesis and surgical procedure. The objective of the study was to review the literature on biomechanical studies for the treatment of lumbar spinal degenerative diseases. A critical review of the clinical and biomechanical studies on fusion spine surgeries was undertaken. The important modeling parameters, challenges, and limitations of the current studies were identified, showing the future research directions.
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Application of an Expandable Cage for Reconstruction of the Cervical Spine in a Consecutive Series of Eighty-Six Patients. ACTA ACUST UNITED AC 2020; 56:medicina56120642. [PMID: 33255605 PMCID: PMC7760022 DOI: 10.3390/medicina56120642] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2020] [Revised: 11/18/2020] [Accepted: 11/23/2020] [Indexed: 12/16/2022]
Abstract
Background and objectives: Expandable cages are frequently used to reconstruct the anterior spinal column after a corpectomy. In this retrospective study, we evaluated the perioperative advantages and disadvantages of corpectomy reconstruction with an expandable cage. Materials and Methods: Eighty-six patients (45 male and 41 female patients, medium age of 61.3 years) were treated with an expandable titanium cage for a variety of indications from January 2012 to December 2019 and analyzed retrospectively. The mean follow-up was 30.7 months. Outcome was measured by clinical examination and visual analogue scale (VAS); myelopathy was classified according to the EMS (European Myelopathy Scale) and gait disturbances with the Nurick score. Radiographic analysis comprised measurement of fusion, subsidence and the C2–C7 angle. Results: Indications included spinal canal stenosis with myelopathy (46 or 53.5%), metastasis (24 or 27.9%), spondylodiscitis (12 or 14%), and fracture (4 or 4.6%). In 39 patients (45.3%), additional dorsal stabilization (360° fusion) was performed. In 13 patients, hardware failure occurred, and in 8 patients, adjacent segment disease occurred. Improvement of pain symptoms, myelopathy, and gait following surgery were statistically significant (p < 0.05), with a medium preoperative VAS of 8, a postoperative score of 3.2, and medium EMS scores of 11.3 preoperatively vs. 14.3 postoperatively. Radiographic analysis showed successful fusion in 74 patients (86%). As shown in previous studies, correction of the C2–C7 angle did not correlate with improvement of neurological symptoms. Conclusion: Our results show that expandable titanium cages are a safe and useful tool in anterior cervical corpectomies for providing adequate anterior column support and stability.
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Lewandrowski KU, Ferrara L, Cheng B. Expandable Interbody Fusion Cages: An Editorial on the Surgeon's Perspective on Recent Technological Advances and Their Biomechanical Implications. Int J Spine Surg 2020; 14:S56-S62. [PMID: 33122184 DOI: 10.14444/7127] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
BACKGROUND Expandable cages have gone through several iterations since they first appeared on the market in the early 2000s. Their development was prompted by some common problems associated with static interbody cages, including migration, expulsion, dural or neural traction injury, and pseudarthrosis. OBJECTIVE To summarize current technological advances from earlier expandable lumbar interbody fusion devices to implants with vertical and medial-to-lateral expansion mechanisms. METHODS The authors review the currently available expandable cage designs, the incremental technological advances, and how these devices impact minimally invasive surgery interbody procedures and clinical outcomes. The strategic concepts intended to improve the minimally invasive application of expandable interbody fusion implants are reviewed from a surgeon's perspective in a clinical context to discuss how their use may improve patient outcomes. CONCLUSIONS The geometrical configuration, effective stiffness of composite multi-material cage designs may impact the bone-implant contact area with the endplates. Hybridization strategies of expandable cage technology with modern minimally invasive and endoscopic spinal surgery techniques are presented by outlining their advantages and disadvantages. LEVEL OF EVIDENCE 1 CLINICAL RELEVANCE: Systematic review.
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Affiliation(s)
- Kai-Uwe Lewandrowski
- Center for Advanced Spine Care of Southern Arizona and Surgical Institute of Tucson, Arizona, Department of Orthopaedics, Fundación Universitaria Sanitas, Bogotá, Colombia, Department of Neurosurgery, Universidade Federal do Estado do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Lisa Ferrara
- OrthoKinetic Technologies LLC, Southport, North Carolina
| | - Boyle Cheng
- Carnegie Mellon University, Neurosurgical and Spine Research, Allegheny General Hospital, Pittsburgh, Pennsylvania
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Zhang J, Pan A, Zhou L, Yu J, Zhang X. Comparison of unilateral pedicle screw fixation and interbody fusion with PEEK cage vs. standalone expandable fusion cage for the treatment of unilateral lumbar disc herniation. Arch Med Sci 2018; 14:1432-1438. [PMID: 30393499 PMCID: PMC6209698 DOI: 10.5114/aoms.2018.74890] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/23/2017] [Accepted: 02/17/2018] [Indexed: 12/18/2022] Open
Abstract
INTRODUCTION This study was conducted to compare the clinical effects of unilateral pedicle screw fixation and interbody fusion with PEEK cage (UPSFC) and standalone expandable fusion cage (SAEFC) on unilateral lumbar disc herniation. MATERIAL AND METHODS From September 2011 to July 2014, a respective investigation was performed on 130 lumbar disc herniation patients treated with SAEFC or UPSFC. The hospital stay, operating time, blood loss, Japanese orthopaedic association scores (JOA), and visual analogue score (VAS) in the two groups were compared using Student's t-test. RESULTS The average of follow-up time was 25.6 ±6.4 and 25.2 ±5.8 months, respectively. No significant difference in the postoperative hospitalizsation, intraoperative blood loss, operative time, and postoperative fusion rate was detected between the two groups. VAS score in the UPSFC group was significantly lower than in the SAEFC group at 6 and 12 months after operation (p = 0.014, p = 0.004). X-ray images indicated that the subsidence rate was 8.1% (5/62) in the SAEFC group, while no subsidence was detected in UPSFC group 12 month after operation. CONCLUSIONS Both SAEFC and UPSFC are effective techniques. UPSFC may be a better choice for patients with lumbar disc herniation and unilateral limb symptoms of nerve root in view of the advantages of better low back pain relief and low subsidence rate.
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Affiliation(s)
- Jinlei Zhang
- Department of Orthopaedics, Zhoukou City Central Hospital, The Affiliated Hospital of Xinxiang Medical College, Zhoukou Shi, China
| | - Aixing Pan
- Department of Orthopaedics, Beijing Chao-Yang Hospital, Capital Medical University, Beijing, China
| | - Li Zhou
- Department of Orthopaedics, Zhoukou City Central Hospital, The Affiliated Hospital of Xinxiang Medical College, Zhoukou Shi, China
| | - Jingyi Yu
- Department of Orthopaedics, Zhoukou City Central Hospital, The Affiliated Hospital of Xinxiang Medical College, Zhoukou Shi, China
| | - Xiao Zhang
- Department of Orthopaedics, Zhoukou City Central Hospital, The Affiliated Hospital of Xinxiang Medical College, Zhoukou Shi, China
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Barrett-Tuck R, Del Monaco D, Block JE. One and two level posterior lumbar interbody fusion (PLIF) using an expandable, stand-alone, interbody fusion device: a VariLift ® case series. JOURNAL OF SPINE SURGERY 2017; 3:9-15. [PMID: 28435912 DOI: 10.21037/jss.2017.02.05] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
BACKGROUND Surgical interventions such as posterior lumbar interbody fusion (PLIF) with and without posterior instrumentation are often employed in patients with degenerative spinal conditions that fail to respond to conservative medical management. The VariLift® Interbody Fusion System was developed as a stand-alone solution to provide the benefits of an intervertebral fusion device without the requirement of supplemental pedicle screw fixation. METHODS In this retrospective case series, 25 patients underwent PLIF with a stand-alone VariLift® expandable interbody fusion device without adjunctive pedicle screw fixation. There were 12 men and 13 women, with a mean age of 57.2 years (range, 33-83 years); single level in 18 patients, 2 levels in 7 patients. Back pain severity was reported as none, mild, moderate, severe and worst imaginable at baseline, 6 and 12 months. Preoperatively, 88% (22 of 25) of patients reported severe back pain. RESULTS All patients experienced symptomatic improvement and, by 12 months postoperatively, 71% (15 of 21) of patients reported only mild residual pain. Overall, pain scores improved significantly from baseline to 12 months (P=0.0002). There were no revision surgeries and fusion was achieved 12 of 13 patients (92%) who returned for a 12-month radiographic follow-up. There were three cases of intractable postsurgical pain which required extended hospitalization or pain management, one wound infection and one case of surgical site dehiscence, both treated and resolved during inpatient hospitalization. CONCLUSIONS In this single-physician case series, the VariLift® device used in single or two-level PLIF provided effective symptom relief and produced a high fusion rate without the need for supplemental fixation.
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Affiliation(s)
| | - Diana Del Monaco
- Wenzel Spine, Inc., 1130 Rutherford Lane, Ste. 200, Austin, TX 78753, USA
| | - Jon E Block
- 2210 Jackson Street, Ste. 401, San Francisco, CA 94115, USA
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Neely WF, Fichtel F, Del Monaco DC, Block JE. Treatment of Symptomatic Lumbar Disc Degeneration with the VariLift-L Interbody Fusion System: Retrospective Review of 470 Cases. Int J Spine Surg 2016; 10:15. [PMID: 27441173 DOI: 10.14444/3015] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
BACKGROUND Many first generation stand-alone fusion cages required endplate decortication and surgical impaction during the procedure resulting in segmental subsidence, implant migration and loss of lordosis postoperatively. The primary objective of this study was to evaluate radiographically, in a large series of patients, whether engineering and design modifications incorporated in a specific stand-alone, expandable interbody fusion device (VariLift(®)-L) adequately addressed previously recognized deficiencies of stand-alone interbody cages. METHODS In this retrospective chart review of 470 patients (642 treated levels), we evaluated radiographic evidence of fusion, subsidence and migration following a one- or two-level PLIF procedure utilizing this stand-alone expandable interbody fusion device. A secondary objective was to corroborate the low morbidity and symptomatic improvements achieved with previous interbody cage devices used to treat symptomatic disc degeneration. RESULTS The average postoperative followup was 3.9 ± 1.8 years and a solid fusion rate of 94% was achieved among patients with ≥ 9 months of radiographic followup. Subsidence > 3 mm was noted at 10 levels with no cases of device migration. Composite back pain severity scores improved from 8.5 ± 1.5 preoperatively to 0.8 ± 1.5 at final followup (p<0.001) and 94% of patients met or exceeded the minimal clinical important difference of 3.8 points. Eighteen patients required reoperation following the index procedure; 16 of these patients were treated for adjacent segment disease. CONCLUSIONS LOE The VariLift-L device has excellent clinical and technical performance characteristics, providing adequate stabilization of the anterior column without the need for supplemental posterior instrumentation. Level of Evidence IV. IRB Approval: Expedited Federal Register Categories 5& 7: Methodist IRB 3/30/2011; Informed Consent statement: retrospective data collection, patients signed consent forms allowing for data to be used for research. CLINICAL RELEVANCE This stand-alone expandable fusion device produced high fusion rates, a low incidence of reoperation and effective symptom relief in a "real world" setting among a large group of patients with refractory symptomatic disc degeneration.
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