High Prevalence of Biofilms on Retrieved Implants from Aseptic Pseudarthrosis Cases

INTRODUCTION

Recent literature has associated pseudarthrosis and pedicle screw loosening with subchronic infection at the pedicle of the vertebra. The positive culture results of a previous retrieval analysis show that such patients have a high frequency of bacterial contamination. The objective of this study is to visually capture the architecture of these undiagnosed infections, which have been described in other studies as biofilms on supposedly "aseptic" screw loosening.

METHODS

Explants from 10 consecutive patients undergoing revision spine surgery for pseudarthrosis were collected and fixed in glutaraldehyde solution. Each of these implants was imaged thoroughly by using scanning electron microscopy and x-ray spectroscopy to evaluate the architecture of the biofilm. Additionally, eight patient swabs from tissues around the implants were sent for cultures to assess bacterial infiltration in tissues beyond the biofilm. The implants were also analyzed using energy dispersive x-ray spectroscopy. The exclusion criteria included clinically diagnosed infection (current or previous) and/or mechanical failure of the implant due to falls/accidents.

RESULTS

The study was successful in capturing the visual architecture of the biofilm on retrieved implants. A total of 77% of pseudarthrosis cases presented with loose pedicle screws, which were diagnosed by a preoperative computed tomography scan showing radiolucency along the screw track and were confirmed intraoperatively, and 72% of the cases showed biofilm on explants.

CONCLUSIONS

In the absence of the clinical presentation of infection, impregnated bacteria could form a biofilm around an implant, and this biofilm can remain undetected via contemporary diagnostic methods, including swabbing. Implant biofilm is frequently present in "aseptic" pseudarthrosis cases.

Updates on Evidence-Based Practices to Reduce Preoperative and Intraoperative Contamination of Implants in Spine Surgery: A Narrative Review

The current communication seeks to provide an updated narrative review on latest methods of reducing implant contaminations used during spine surgery. Recent literature review has shown that both preoperative reprocessing and intraoperative handling of implants seem to contaminate implants. In brief, during preoperative phase, the implants undergo repeated bulk cleaning with dirty instruments from the OR, leading to residue buildup at the interfaces and possibly on the surfaces too. This, due to its concealed nature, remains unnoticed by the SPD (sterile processing department) or other hospital staff. Nevertheless, these can be avoided by using individually prepackaged presterilized implants. In the intraoperative phase, the implants (in the sterile field) are directly touched by the scrub tech with soiled (assisting the surgeon dispose the tissues from the instruments in use) gloves for loading onto an insertion device. It is then kept exposed on the working table (either separately or next to the used instruments as the pedicles hole are being prepared). Latest investigation has shown that by the time it is implanted in the patient, it can harbor up to 10e7 bacterial colony-forming units. The same implants were devoid of such colony-forming units, when sheathed by an impermeable sterile sheath around the sterile implant.

Biomechanical Comparison of a Novel Percutaneous Transfacet Device and a Traditional Posterior System for Single Level Fusion

Posterior spinal fusions are indicated for a variety of spinal disorders. Transfacet fixation minimizes soft tissue disruption and preserves the adjacent facet joint. This technique is uncommon due to concerns with biomechanical stability and proper implant placement. For these reasons, a length adjustable implant may obviate the clinical concerns but necessitates biomechanical study. This study evaluated the in vitro biomechanical stability between a novel transfacet fixation device compared with standard pedicle screws during cyclic physiologic loading in a human cadaveric model. Cadaveric L4-L5 lumbar motion segments from 16 human spines were tested in cyclic flexion/extension, lateral bending, and torsion after insertion of either transfacet fixation devices or 5.5 mm pedicle screw instrumentation. A load cell was used to measure the compressive forces on the anterior column during testing. Motion segment stiffness and anterior column compression were analyzed with a 1-way analysis of variance (P<0.05). The transfacet device demonstrated a statistically similar stiffness when compared with the pedicle screw system for each test direction. For anterior column loading during physiologic testing, there were no biomechanical differences between stabilization systems. Percutaneous transfacet fixation is an attractive surgical option for single-level spinal fusions. A biomechanical evaluation of a novel device for this application demonstrated similar stability to a pedicle screw system. The length adjustability of the device may alleviate concerns for precise device placement and the biomechanical stability may produce similar rates and quality of posterior spinal fusions.

Surgically related upper cervical spine canal anatomy in children

MRI studies of the upper spines of 121 children were evaluated to precisely define the sagittal anatomy at C1 in the pediatric population. The diameters of the spinal cord, bony canal, space available for the cord (SAC), dens+atlanto-dens interval (ADI), and "free" space were measured. The results demonstrate an accelerated growth in the C1 canal, dens + ADI, and SAC during the first four years after birth. Steel's rule of thirds was shown to roughly hold true throughout childhood. Neonates have an average SAC diameter of 12.4 mm, a value less than the 13 mm dimension commonly used to define relative stenosis in children.

Cervical stability after sequential capsule resection

A portion of the cervical facet joint must be resected to expose and decompress cervical nerve roots from a posterior approach. When posterior fusion is performed, it is common to remove the facet capsule only for the joints being fused. This study was performed to examine the effect of resection of the facet capsule alone, without disruption of the bony facet to determine what degree of facet-capsule resection leads to acute instability. Seven human cervical cadaveric spines were used in the experiment. Nondestructive biomechanical testing was performed in axial load, flexion, extension, and torsion. Each specimen was tested intact and after sequential resection of 25%, 50%, 75%, and 100% of the C5-6 facet capsules. Axial stiffness changed very little during the experiment. In torsion, the displacement increased 1% after a 25% capsule resection, 19% after a 50% resection, and 25% after a 75% or 100% resection. No gross subluxation was seen during the torsional test. In the flexion test, posterior displacement increased 4% after a 25% resection, 5% after a 50% resection, 32% after a 75% resection, and 22% after a 100% resection. There was a statistically increased displacement seen during the flexion test after 75% or 100% of capsule resection. Thus, significant hypermobility did occur during both torsion and flexion testing with greater than 50% resection of the facet capsules. Great care should be taken when exposing an unfused facet to limit facet-capsule resection to less than 50%. With resection of greater than 50% of the capsule, postoperative hypermobility can occur and may require stabilization.

Blunt injuries to the extracranial cerebral vessels associated with spine fractures

Injury of the extracranial carotid or vertebral artery with associated spine fractures is a rare but documented entity. In this article, four cases are examined in which patients suffered axial fractures after motor vehicle accidents and subsequently were found to have pathology in one or more of the extracranial arteries. Misdiagnosis is a common complication because symptoms from this are often attributable to closed head injury. Early detection and treatment, however, are essential. As many as 40% of the cases reported have permanent neurologic deficit. Although cerebral angiography remains the diagnostic gold standard, other modalities (eg, transcranial doppler and magnetic resonance angiography) continue to be examined. The treatment of these lesions remains controversial. A variety of surgical procedures may be applicable depending on the time between the injury and the onset of symptoms, the location of the vascular injury, and the rapidity of diagnosis. Anticoagulation therapy appears to play a large role in the management of patients with injury of the extracranial carotid or vertebral artery.

A study of computer-assisted tomography. II. Comparison of metrizamide myelography and computed tomography in the diagnosis of herniated lumbar disc and spinal stenosis

One hundred twenty-two patients with surgically confirmed pathology consisting of either herniated lumbar disc, spinal stenosis, or both were included in this investigation. For each of these patients, preoperative metrizamide myelography and computerized tomography were performed. Each myelogram and CT scan was read blindly so that the neuroradiologist interpreting the study had no knowledge of the patient's surgical pathology, clinical examination, nor any knowledge of the interpretation of the other preoperative test. A painstaking attempt was made to describe precisely both the exact nature of the preoperative myelogram and CT scan interpretations. The correlations between the preoperative interpretation of each test and the observed surgical findings then were analyzed statistically. Based upon this analysis, myelography was found to be more accurate than computed tomography in the diagnosis of herniated lumbar disc (83% vs. 72%). In the diagnosis of spinal stenosis, myelography was slightly more accurate than computed tomography (93% vs. 89%). Based upon the results of this study, the authors conclude that metrizamide myelography is more accurate than computed tomography in the diagnosis of both herniated lumbar disc and spinal stenosis and remains the diagnostic study of choice for these conditions. Furthermore, metrizamide myelography gives the added advantage of visualizing the thoracolumbar junction and, thus, affords the opportunity to diagnose occult spinal tumors.

Pitfalls in the use of the Pavlik harness for treatment of congenital dysplasia, subluxation, and dislocation of the hip

We reviewed the records of treatment of eighteen infants with congenital dysplasia, subluxation, or dislocation of the hip who had problems with the involved hip following treatment with the Pavlik harness. The most common problem (seen in twelve patients with a dislocated hip) was failure to obtain reduction. This failure was attributed primarily to improper use of the harness by the physician. In some patients, three to five months elapsed before the physician recognized the lack of reduction. In nine patients, a Pavlik harness of poor quality and construction added to both the physician's and the patient's problems, and in six patients, poor patient compliance with the use of the harness was partially responsible for the failure. In three patients who were initially treated in the Pavlik harness, avascular necrosis of the hip subsequently developed, in two following open reduction and in one after closed reduction and cast application. The physician's indications for use and application of the harness must be appropriate. The child must be examined frequently out of the harness both clinically and roentgenographically. Failure to achieve reduction or adductor relaxation must be recognized promptly and dealt with immediately.

Acute exertional superficial posterior compartment syndrome

This case report of an acute exertional compartment syndrome involving predominantly the superficial posterior compartment emphasizes several important facts: (1) The subacute recurring syndromes, if left untreated, may develop into an acute syndrome. (2) The diagnostic findings separating the acute syndrome from the chronic forms are marked pain with passive stretch of the involved muscles, paresis, and sensory deficit.8,12,15, (3) In the acute form, immediate fasciotomy is mandatory and often results in full recovery. (4) All four major compartments of the leg are susceptible to chronic or acute compartment syndromes initiated by exertion. These compartments can be decompressed as necessary through a limited skin incision as recently reported.11 (5) The need for an easily obtainable and reproducible method for measuring intracompartment pressures (e.g., the wick catheter technique) is indicated.