Hidden blood loss during posterior spine fusion surgery.

Background Context: Posterior spine fusion is associated with significant intra- and postoperative blood losses. When referring to the total blood loss during spine surgery, the standard is to measure the intraoperative bleeding plus the postoperative drainage. This ignores the "hidden" blood loss that was found to be significant in other fields of surgery.

Cervical intervertebral disc replacement.

Symptomatic adjacent-level disease after cervical fusion has led to the development and testing of several disc-replacement prostheses. Randomized controlled trials of cervical disc replacement (CDR) compared with anterior cervical discectomy and fusion (ACDF) have demonstrated at least equivalent clinical results for CDR with similar or lower complication rates. Biomechanical, kinematic, and radiographic studies of CDR reveal that the surgical level and adjacent vertebral level motion and center of rotation more closely mimic the native state.

Pedicle screw-based posterior dynamic stabilization: literature review.

Posterior dynamic stabilization (PDS) indicates motion preservation devices that are aimed for surgical treatment of activity related mechanical low back pain. A large number of such devices have been introduced during the last 2 decades, without biomechanical design rationale, or clinical evidence of efficacy to address back pain. Implant failure is the commonest complication, which has resulted in withdrawal of some of the PDS devices from the market.

Lateral transpsoas fusion: indications and outcomes.

Spinal fusion historically has been used extensively, and, recently, the lateral transpsoas approach to the thoracic and lumbar spine has become an increasingly common method to achieve fusion. Recent literature on this approach has elucidated its advantage over more traditional anterior and posterior approaches, which include a smaller tissue dissection, potentially lower blood loss, no need for an access surgeon, and a shorter hospital stay. Indications for the procedure have now expanded to include degenerative disc disease, spinal stenosis, degenerative scoliosis, nonunion, trauma, infection, and low-grade spondylolisthesis.

Single- versus multilevel fusion for single-level degenerative spondylolisthesis and multilevel lumbar stenosis: four-year results of the spine patient outcomes research trial.

Study Design: A subanalysis study.

Objective: To compare surgical outcomes and complications of multilevel decompression and single-level fusion with multilevel decompression and multilevel fusion for patients with multilevel lumbar stenosis and single-level degenerative spondylolisthesis (DS).

Summary Of Background Data: In patients with DS who are treated surgically, decompression and fusion provide a better clinical outcome than decompression alone.

Instant axis of rotation of L4-5 motion segment--a biomechanical study on cadaver lumbar spine.

The instant axis of rotation (IAR) is an important kinematic property to characterise of lumbar spine motion. The goal of this biomechanical study on cadaver lumbar spine was to determine the excursion of the IAR for flexion (FE), lateral bending (LB) and axial rotation (AR) motion at L4-5 segment. Ten cadaver lumbar spine specimens were tested in a 6 degrees-of-freedom spine tester with continuous clyclical loading using pure moment and follower pre-load, to produce physiological motion.

In vitro response of human chondrocytes to a combination of growth factors and a proteinase inhibitor.

Degenerative disk disease is an accelerating cascade of tissue degeneration in the intervertebral disk. A harsh catabolic environment perpetuates the degeneration of the intervertebral disk. Tissue engineering-based techniques offer effective treatment to slow the progression of degenerative disk disease and regenerate intervertebral disk tissue.

Supercritical carbon dioxide processed resorbable polymer nanocomposite bone graft substitutes.

The development of synthetic bone graft substitutes is an intense area of research due to the complications associated with the harvest of autogenous bone and concerns about the supply of allogenic bone. Porous resorbable polymers have been used extensively in hard tissue engineering applications, but currently lack load-bearing capacity. Supercritical carbon dioxide (scCO(2)) processing is used as a novel method to simultaneously impart a porous structure and disperse a nano-clay in a resorbable polymer matrix suitable for load-bearing applications.

Analysis of in vivo corrosion of 316L stainless steel posterior thoracolumbar plate systems: a retrieval study.

Study Design: One hundred eighteen patients retrieved 316L stainless steel thoracolumbar plates, of 3 different designs, used for fusion in 60 patients were examined for evidence of corrosion. A medical record review and statistical analysis were also carried out.

Objective: This study aims to identify types of corrosion and examine preferential metal ion release and the possibility of statistical correlation to clinical effects.

Spinal orthoses.

External orthoses are used in the management of a variety of spinal disorders. Many types of brace are available to support the cervical, thoracic, and lumbar spine as well as junctional regions, which have special mechanical considerations. Many prefabricated and custom-made devices are available, made by a variety of manufacturers in this unregulated area of medical practice.

Debating the value of spine surgery.

Lumbar arthrodesis is a commonly performed operative procedure for the treatment of low back pain. Recently, total disc arthroplasty has gained some acceptance among surgeons and patients. However, the indications for and results of back pain surgery remain controversial and confusing.

Distractive force relative to initial graft compression in an in vivo anterior cervical discectomy and fusion model.

Study Design: An in vivo biomechanical anterior cervical discectomy and instrumented fusion (ACDFI) model employing a calibrated distractor and a subminiature load cell used to intraoperatively measure distractive force across the discectomy site and subsequent compressive force across the interbody load cell following distractor removal.

Objective: To determine the relationship between the distractive force and resultant initial graft compression in an in vivo ACDFI model.

Summary Of Background Data: The relationship between the distractive force and subsequent graft compression following distractor removal has not been studied in an in vivo ACDFI model.

Biomimetic calcium phosphate coatings as bone morphogenetic protein delivery systems in spinal fusion.

Background Context: Use of recombinant human bone morphogenetic protein-2 (rhBMP-2) has been shown to enhance spinal fusion rates. Case reports of soft-tissue swelling, ectopic bone formation, and osteolysis have recently surfaced. It is hypothesized that incorporation of rhBMP-2 within a calcium phosphate (CaP) coating may help to localize delivery and mitigate these complications.

Biomechanical evaluation of the kinematics of the cadaver lumbar spine following disc replacement with the ProDisc-L prosthesis.

Study Design: Biomechanical study of the ProDisc-L in a cadaveric model under pure moment loading. OBJECTIVE.: To determine the kinematic properties of a lumbar spine motion segment and the adjacent level following ProDisc-L disc replacement in the cadaveric spine.

Degenerative lumbar spondylolisthesis: evolution of surgical management.

Watters III WC, Bono CM, Gilbert TJ, et al. An evidence-based clinical guideline for the diagnosis and treatment of degenerative lumbar spondylolisthesis. Spine J 2009;9:609-14 (this issue).

Development of a 4-axis load cell used for lumbar interbody load measurements.

Numerous studies have assessed lumbar interbody fusion, but little data from direct interbody load measurements exists. This manuscript describes an interbody fusion cage with integrated 4-axis load cell that can simulate implant heights of 13, 15, 17, 19 and 21 mm. The calibrated load cell was accurate to within 7.

Effects of disc height and distractive forces on graft compression in an anterior cervical corpectomy model.

Study Design: An in vitro biomechanical study using a calibrated distractor and a subminiature load cell in a cadaveric cervical corpectomy construct.

Objective: To study the inter-relationships of defect height, graft height, and compressive and distractive forces in an anterior cervical corpectomy model.

Summary Of Background Data: The effects of graft size on compressive and distractive forces in cervical corpectomy remain unknown.

Early failure of bioabsorbable anterior cervical fusion plates: case report and failure analysis.

Study Design: Case report with forensic failure analysis.

Objective: To determine the failure modes of 3 explanted 70:30 PLDLA Mystique (Medtronic Sofamor Danek, Memphis, TN) graft containment plates retrieved from revision surgery for early device failure.

Summary Of Background Data: To reduce the problems of stress-shielding and radiopacity associated with metallic systems, bioabsorbable polymers have been used in anterior cervical discectomy and fusion procedures.