Innovation and New Technologies in Spine Surgery, Circa 2020: A Fifty-Year Review.

Spine surgery (lumbar, cervical, deformity, and entire spine) has increased in volume and improved in outcomes over the past 50 years because of innovations in surgical techniques and introduction of new technologies to improve patient care. Innovation is described as a process to add value or create change in an enterprise's economic or social potential. This mini review will assess two of three assessments of innovation in spine surgery: scientific publications and patents issued.

Contribution of Round vs. Rectangular Expandable Cage Endcaps to Spinal Stability in a Cadaveric Corpectomy Model.

Background: Expandable cages are gaining popularity in anterior reconstruction of the thoracolumbar spine following corpectomy as they can provide adjustable distraction and deformity correction. Rectangular, rather than circular, endcaps provide increased resistance to subsidence by spanning the apophyseal ring; however their impact on construct stability is not known. The objective of this study was to investigate the contribution of expandable corpectomy cage endcap shape (round vs.

Controlled motion with the XL-TDR lateral-approach lumbar total disk replacement: in vitro kinematic investigation.

Objective: Anterior-approach total disk replacement (TDR) devices are thought to retain close to so-called normal range of motion (ROM); however, they are also inherently unstable due to resection of the anterior longitudinal ligament and annulus. This instability/laxity is manifested as increased neutral zone (NZ) motion. The XL-TDR device (NuVasive, Inc.

Biomechanical stability of lateral interbody implants and supplemental fixation in a cadaveric degenerative spondylolisthesis model.

Study Design: In vitro cadaveric biomechanical study of lateral interbody cages and supplemental fixation in a degenerative spondylolisthesis (DS) model.

Objective: To investigate changes in shear and flexion-extension stability of lateral interbody fusion constructs.

Summary Of Background Data: Instability associated with DS may increase postoperative treatment complications.

Biomechanical evaluation of stand-alone lumbar polyether-ether-ketone interbody cage with integrated screws.

Background Context: Stand-alone interbody cages with integrated screws potentially provide a biomechanically stable solution for anterior lumbar interbody fusion (ALIF) that alleviates the need for additional exposure for supplemental fixation, thereby reducing the chance of additional complications and morbidity.

Purpose: To compare the stability of a stand-alone anterior interbody fusion system with integrated fixation screws against traditional supplemental fixation methods and to evaluate the difference between three and four fixation screws in the stand-alone cage.

Study Design: In vitro cadaveric biomechanical study.

Lordosis restoration after anterior longitudinal ligament release and placement of lateral hyperlordotic interbody cages during the minimally invasive lateral transpsoas approach: a radiographic study in cadavers.

Object: In the surgical treatment of spinal deformities, the importance of restoring lumbar lordosis is well recognized. Smith-Petersen osteotomies (SPOs) yield approximately 10° of lordosis per level, whereas pedicle subtraction osteotomies result in as much as 30° increased lumbar lordosis. Recently, selective release of the anterior longitudinal ligament (ALL) and placement of lordotic interbody grafts using the minimally invasive lateral retroperitoneal transpsoas approach (XLIF) has been performed as an attempt to increase lumbar lordosis while avoiding the morbidity of osteotomy.

Biomechanical analysis in a human cadaveric model of spinous process fixation with an interlaminar allograft spacer for lumbar spinal stenosis: Laboratory investigation.

Object: Traditional posterior pedicle screw fixation is well established as the standard for spinal stabilization following posterior or posterolateral lumbar fusion. In patients with lumbar spinal stenosis requiring segmental posterior instrumented fusion and decompression, interlaminar lumbar instrumented fusion (ILIF) is a potentially less invasive alternative with reduced morbidity and includes direct decompression assisted by an interlaminar allograft spacer stabilized by a spinous process plate. To date, there has been no biomechanical study on this technique.

Teaching medical device design using design control.

The design of medical devices requires an understanding of a large number of factors, many of which are difficult to teach in the traditional educational format. This subject benefits from using a challenge-based learning approach, which provides focused design challenges requiring students to understand important factors in the context of a specific device. A course was designed at San Diego State University (CA, USA) that applied challenge-based learning through in-depth design challenges in cardiovascular and orthopedic medicine, and provided an immersive field, needs-finding experience to increase student engagement in the process of knowledge acquisition.

Biomechanical analysis and review of lateral lumbar fusion constructs.

Study Design: Biomechanical study and the review of literature on lumbar interbody fusion constructs.

Objective: To demonstrate the comparative stabilizing effects of lateral interbody fusion with various supplemental internal fixation options.

Summary Of Background Data: Lumbar interbody fusion procedures are regularly performed using anterior, posterior, and more recently, lateral approaches.

Evaluation of a bioresorbable polylactide sheet for the reduction of pelvic soft tissue attachments in a porcine animal model.

In an adult porcine model, the effectiveness of a bioresorbable film to minimize soft tissue attachment to the pelvic viscera was evaluated at 4-week and 12-week endpoints. Following a transperitoneal laparotomy through a midline incision, the bladder and uterus were abraded in all animals to promote soft tissue attachment to the viscera. Control animals received no further treatment.

MacroPore resorbable devices in craniofacial surgery.

Resorbable polymer implants have become a compelling option in the treatment of acquired and congenital craniofacial deformities. The resorbable polylactide (PLa) and polyglycolide (PGa) polymers in particular have demonstrated excellent safety profile sin multiple in vitro, animal, and clinical studies and are currently being used in a wide variety of craniofacial applications. In this article, the authors discuss the biomaterial properties of PLa and PGa resorbable implants and provide an overview of the use of these polymers in craniofacial surgery.

In vivo evaluation of bioresorbable polylactide implants for cervical graft containment in an ovine spinal fusion model.

Object: An in vivo study was conducted in an ovine model to investigate the biomechanical changes after the animals underwent single-level anterior cervical discectomy followed by fusion in which autologous tricortical graft was used and implantation of cervical plates for which bioresorbable polymer screws and plates were used. The specific aims of the study were to evaluate whether implant failure or screw backout would occur over time and to measure the change in stiffness at the treated level at various postoperative time periods (3, 6, and 12 months).

Methods: A total of 58 x-ray films were evaluated over the 12-month survival period.

Use of polylactide resorbable film as a barrier to postoperative peridural adhesion in an ovine dorsal laminectomy model.

Object: The purpose of this study was to evaluate the performance of a resorbable polylactide film in the sheep posterior spine in the presence of a combined laminectomy and durotomy defect.

Methods: A resorbable polylactide film was used to cover the combined defects in the eight sheep used in this study. Two surgical levels were performed in each animal, with randomly assigned control and treated sites.

Resorbable posterolateral graft containment in a rabbit spinal fusion model.

Object: The authors studied the effect of a resorbable graft containment device in a rabbit posterolateral lumbar spinal fusion model.

Methods: Twenty rabbits were divided into four groups: autologous bone graft (ABG), ABG with the MacroPore containment device (ABG + MP), demineralized bone matrix (DBM), and DBM with the containment device (DBM + MP). Fusion mass was assessed at 6 weeks with high-resolution radiography and volumetric computerized tomography.

Use of a resorbable sheet in iliac crest reconstruction in a sheep model.

Object: Iliac crest bone graft harvesting can result in major complications, the rates of which range from approximately 6 to 8%. The objective of this study was to evaluate the postoperative regeneration of iliac crest donor defects in an animal model after harvesting a full-thickness tricortical graft.

Methods: In skeletally mature sheep, a tricortical iliac crest graft was harvested.

Bioabsorbable anterior lumbar plate fixation in conjunction with cage-assisted anterior interbody fusion.

Object: An in vitro biomechanical study was conducted to determine the effects of anterior stabilization on cage-assisted lumbar interbody fusion biomechanics in a multilevel human cadaveric lumbar spine model.

Methods: Three spine conditions were compared: harvested, bilateral multilevel cages (CAGES), and CAGES with bioabsorbable anterior plates (CBAP), tested under flexion-extension, lateral bending, and axial rotation. Measurements included vertebral motion, applied load, and bending/rotational moments.

Feasibility of a resorbable anterior cervical graft containment plate.

In this article the authors review the history of anterior cervical plating for one- and two-level discectomy for degenerative disease and provide background justification for the design and testing of a cervical plate composed of a resorbable material. The design of the plate is discussed with special reference to modifications of its design and tools compared with metallic plates that are necessary because of the different mechanical properties of the less rigid material. The cadaveric and animal in vivo testing methodologies are described, and a novel testing method for reliably quantifying graft containment is also described.

Evaluation of 70/30 poly (L-lactide-co-D,L-lactide) for use as a resorbable interbody fusion cage.

Object: Titanium lumbar interbody spinal fusion devices are reported to be 90% effective in cases requiring single-level lumbar interbody arthrodesis, although radiographic determination of fusion has been debated.

Methods: Using blinded radiographic, biomechanical, histological, and statistical measures, researchers in the present study evaluated a radiolucent 70/30 poly(L-lactide-co-D,L-lactide) interbody fusion device packed with autograft or recombinant human bone morphogenetic protein-2 on a collagen sponge in 25 sheep at 3, 6, 12, 18, and 24 months. A trend of increased fusion stiffness, radiographic fusion, and histologically confirmed fusion was demonstrated at 3 months to 24 months postimplantation.

Use of polylactide resorbable film as an adhesion barrier.

Object: The present investigation evaluates two thicknesses of a resorbable polylactic acid (PLA) barrier film as an adhesion barrier to posterior spinal scar formation.

Methods: A readily contourable, thin film was placed directly over the dura. The thick film was placed above the lamina defect to act as a physical barrier inhibiting the prolapse of soft tissue into the epidural space.

Resorbable posterolateral graft containment in a rabbit spinal fusion model.

The effect of a resorbable graft containment device was evaluated in a rabbit posterolateral lumbar spinal fusion model. Twenty rabbits were divided into four groups: autogenous bone graft (ABG), ABG with the MacroPore containment device (MacroPore Biosurgery Inc, San Diego, Calif) (ABG+MP), demineralized bone matrix (DBM), and DBM with the containment device (DBM+MP). Fusion mass was assessed at 6 weeks with high resolution radiographs and volumetric computed tomography (CT).

Use of a resorbable sheet in iliac crest reconstruction in a sheep model.

Iliac crest bone graft harvesting can result in major complications that occur at rates of approximately 6%-8%. The objective of this study was to evaluate the postoperative regeneration of iliac crest donor defects in an animal model after harvesting a full-thickness tricortical graft. In skeletally mature sheep, a tricortical iliac crest graft was harvested.

Bioabsorbable anterior lumbar plate fixation in conjunction with anterior interbody fusion cages.

An in vitro biomechanical study was conducted to determine the effects of anterior stabilization on lumbar interbody cage fusion biomechanics in a multilevel human cadaveric lumbar model. Three spine conditions were compared: harvested, bilateral multilevel cages (CAGES), and CAGES with bioabsorbable anterior plates (CBAP), tested under flexion/extension, lateral bending, and axial rotation. Measurements included vertebral motion, applied load, and bending/rotational moments.

Feasibility of a resorbable anterior cervical graft containment plate.

In this article we review the background of anterior cervical plating for one- and two-level diskectomy for degenerative disease and provide background justification for the design and testing of a cervical plate composed of a resorbable material. The design of the plate is discussed with special reference to modifications of implant design and implant tools compared with metallic plates that are necessary because of the different mechanical properties of the less rigid material. Our cadaveric and animal in vivo testing methodologies are described and a novel testing method for reliably quantifying graft containment is also described.