Artifacts in computed tomography (CT) and magnetic resonance imaging (MRI) due to titanium implants in spine surgery are known to cause difficulties in follow-up imaging, radiation planning, and precise dose delivery in patients with spinal tumors. Carbon fiber–reinforced polyetheretherketon (CFRP) implants aim to reduce these artifacts. Our aim was to analyze susceptibility artifacts of these implants using a standardized in vitro model. Titanium and CFRP screw-rod phantoms were embedded in 3% agarose gel. Phantoms were scanned with Siemens Somatom AS Open and 3.0-T Siemens Skyra scanners. Regions of interest (ROIs) were plotted and analyzed for CT and MRI at clinically relevant localizations. CT voxel–based imaging analysis showed a significant difference of artifact intensity and central overlay between titanium and CFRP phantoms. For the virtual regions of the spinal canal, titanium implants (ti) presented − 30.7 HU vs. 33.4 HU mean for CFRP (p < 0.001), at the posterior margin of the vertebral body 68.9 HU (ti) vs. 59.8 HU (CFRP) (p < 0.001) and at the anterior part of the vertebral body 201.2 HU (ti) vs. 70.4 HU (CFRP) (p < 0.001), respectively. MRI data was only visually interpreted due to the low sample size and lack of an objective measuring system as Hounsfield units in CT. CT imaging of the phantom with typical implant configuration for thoracic stabilization could demonstrate a significant artifact reduction in CFRP implants compared with titanium implants for evaluation of index structures. Radiolucency with less artifacts provides a better interpretation of follow-up imaging, radiation planning, and more precise dose delivery.

/pdf/carbon-fiber-reinforced-peek-versus-titanium-implants-an-in-2vglk1spai.pdf

Carbon fiber-reinforced PEEK versus titanium implants: an in vitro comparison of susceptibility artifacts in CT and MR imaging.

Few clinical studies have reported polyetheretherketone (PEEK) rod pedicle screw spinal instrumentation systems (CD-Horizon Legacy PEEK rods; Medtronic, Minneapolis, Minnesota). This article describes a clinical series of 52 patients who underwent posterior spinal fusion using the PEEK Rod System between 2007 and 2010. Of the 52 patients, 25 had degenerative disk disease, 10 had lateral recess stenosis, 6 had degenerative spondylolisthesis, 6 had lumbar spine vertebral fracture, 4 had combined lateral recess stenosis and degenerative spondylolisthesis, and 1 had an L5 giant cell tumor. Ten patients had 1-segment fusion, 29 had 2-segment fusion, and 13 had 3-segment fusion. Mean follow-up was 3 years (range, 1.5-4 years); no patient was lost to follow-up. Clinical evaluation was performed using the Oswestry Disability Index and a low back and leg visual analog pain scale. Imaging evaluation of fusion was performed with standard and dynamic radiographs. Complications were recorded. Mean Oswestry Disability Index scores improved from 76% preoperatively (range, 52%-90%) to 48% at 6 weeks postoperatively, and to 34%, 28%, and 30% at 3, 6, and 12 months postoperatively, respectively. Mean low back and leg pain improved from 8 and 9 points preoperatively, respectively, to 6 and 5 points immediately postoperatively, respectively, and to 2 points each thereafter. Imaging union of the arthrodesis was observed in 50 (96%) patients by 1-year follow-up. Two patients sustained screw breakage: 1 had painful loss of sagittal alignment of the lumbar spine and underwent revision spinal surgery with pedicle screws and titanium rods and the other had superficial wound infection and was treated with wound dressing changes and antibiotics for 6 weeks. No adjacent segment degeneration was observed in any patient until the time of this writing.

/pdf/posterior-spinal-fusion-using-pedicle-screws-1rnulxp3de.pdf

Posterior spinal fusion using pedicle screws.

Lumbar spinal fusion using rigid rods is a common surgical technique. However, adjacent segment disease and other adverse effects can occur. Dynamic stabilization devices preserve physiologic motion and reduce painful stress but have a high rate of construct failure and reoperation. Polyetheretherketone (PEEK) rods for semi-rigid fusions have a similar stiffness and adequate stabilization power compared with titanium rods, but with improved load sharing and reduced mechanical failure. The purpose of this paper is to review and evaluate the clinical and biomechanical performance of PEEK rods. A systematic review of clinical and biomechanical studies was conducted. A literature search using the PubMed, EMBASE, and Cochrane Library databases identified studies that met the eligibility criteria. Eight clinical studies and 15 biomechanical studies were included in this systematic review. The visual analog scale and the Oswestry disability index improved significantly in most studies, with satisfactory fusion rates. The occurrence of adjacent segment disease was low. In biomechanical studies, PEEK rods demonstrated a superior load-sharing distribution, a larger adjacent segment range of motion, and reduced stress at the rod-screw/screw-bone interfaces compared with titanium rods. The PEEK rod construct was simple to assemble and had a reliable in vivo performance compared with dynamic devices. The quality of clinical studies was low with confounding results, although results from mechanical studies were encouraging. There is no evidence strong enough to confirm better outcomes with PEEK rods than titanium rods. More studies with better protocols, a larger sample size, and a longer follow-up time are needed.

Clinical and biomechanical researches of polyetheretherketone (PEEK) rods for semi-rigid lumbar fusion: a systematic review

Traditional materials for the spine such as titanium and stainless steel have produced satisfying long-term fusion rates, mainly due to their strength and stiffness. However, although fixation with titanium rods leads to high fusion rates, increased stiffness of titanium constructs may also contribute to stress shielding and adjacent segment degeneration. Dynamic and flexible materials such as the Dynesys system allow better stress distribution to all of the spinal columns, but increase the rate of complications including screw loosening, infection, back and leg pain, and endplate vertebral fracture. Semi-rigid instrumentation systems using rods made from synthetic polymers such as the polyetheretherketone (PEEK) have been recently introduced as an alternative biomaterial for the spine. PEEK is a fully biocompatible and inert semi-crystalline thermoplastic polymer with minimal toxicity; it has a modulus of elasticity between that of cortical and cancellous bone, and significantly lower than titanium. However, there are very few clinical studies with small sample size and short-term follow-up using PEEK rod-pedicle screw spinal instrumentation systems. Additionally, their results are conflicting. To enhance the literature, this review discusses the effect of this medical for the spine and summarizes the results of the most important related series.

PEEK rod systems for the spine.

Fusion and rigid instrumentation have been currently the mainstay for the surgical treatment of degenerative diseases of the spine over the last 4 decades. In all over the world the common experience was formed about fusion surgery. Satisfactory results of lumbar spinal fusion appeared completely incompatible and unfavorable within years. Rigid spinal implants along with fusion cause increased stresses of the adjacent segments and have some important disadvantages such as donor site morbidity including pain, wound problems, infections because of longer operating time, pseudarthrosis, and fatigue failure of implants. Alternative spinal implants were developed with time on unsatisfactory outcomes of rigid internal fixation along with fusion. Motion preservation devices which include both anterior and posterior dynamic stabilization are designed and used especially in the last two decades. This paper evaluates the dynamic stabilization of the lumbar spine and talks about chronologically some novel dynamic stabilization devices and thier efficacies.

/pdf/dynamic-stabilization-for-challenging-lumbar-degenerative-4tdslqgq0y.pdf

Dynamic Stabilization for Challenging Lumbar Degenerative Diseases of the Spine: A Review of the Literature

Epidermoid tumors are uncommon entities that usually occur intradurally in the cerebellopontine angle and parasellar cisterns. The few cases that have been reported to occur in the intraorbital location involve patients in the first four decades of life. To our knowledge, an elderly person presenting with an orbital epidermoid tumor has never been reported. A 67-year-old man presented with left-sided headache and eye pain. He was found to have a hemorrhagic lesion eroding bone of the greater and lesser wings of the sphenoid that was compressing the frontal and temporal lobes and displacing the globe. Significant edema of the frontal lobe was noted. Aggressive surgical excision was performed with cranioplasty and orbital reconstruction. Near resolution of the patient’s proptosis and eye pain was achieved. Histologic analysis revealed the lesion to be an epidermoid tumor. Hemorrhage into a growing intradiploic orbital epidermoid and surrounding frontal lobe edema created an unusual presentation of this rarely occurring entity in an elderly man. Surgical excision allowed appropriate histologic diagnosis and resolution of symptoms. Epidermoid tumor is a rare but possible entity in the differential diagnosis of elderly patients presenting with acute ocular pain and proptosis.

Uncommon presentation of an intradiploic orbital epidermoid tumor: case report

Study design Retrospective case series. Objective The purpose of our study was to retrospectively review the results of posterior lumbar fusion using polyetheretherketone (PEEK) rods. Summary of background data Pedicle screw and rod instrumentation has become the preferred technique for performing stabilization and fusion in the lumbar spine for degenerative disease. Rigid fixation with titanium rods leads to high fusion rates, but may also contribute to stress shielding and adjacent segment degeneration (ASD). Thus, some have advocated using semirigid rods made of PEEK. Although the biomechanical properties of PEEK rods have shown improved stress-shielding characteristics and anterior load-sharing properties, there are very few clinical studies evaluating their application in the lumbar spine. Methods We evaluated a retrospective cohort of 42 patients who underwent posterior lumbar fusion from 2007 to 2009 for the treatment of lumbar spine degenerative disease using PEEK rods. Reoperation rate was the primary outcome evaluated. Fusion rate was also evaluated. Results Eight of the 42 patients with PEEK rods required reoperation. Reasons for reoperation mainly included ASD (5/8) and nonunion with cage migration (3/8). Radiographically, documented fusion rate was 86%. Mean follow-up was 31.4 months. No statistical differences were found in fusion rates or reoperation between age above 55 years and younger than 55 years (P=1.00), male and female (P=0.110), single or multilevel fusion (P=0.67), and fusion with and without an interbody graft (P=0.69). Smokers showed a trend towards increased risk of reoperation for ASD or instrumentation failure (P=0.056). Conclusions PEEK rods demonstrate a similar fusion and reoperation rate in comparison to other instrumentation modalities in the treatment of degenerative lumbar spine disease.

Polyetheretherketone (PEEK) Rods in Lumbar Spine Degenerative Disease: A Case Series.

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Uncommon presentation of an intradiploic orbital epidermoid tumor: case report

Polyetheretherketone (PEEK) Rods in Lumbar Spine Degenerative Disease: A Case Series.