Ralph J. Mobbs

Effect of cervical hard collar on intracranial pressure after head injury

Background:  Patients suffering head trauma are at high risk of having a concomitant cervical spine injury. A rigid cervical collar is usually applied to each patient until spinal stability is confirmed. Hard collars potentially cause venous outflow obstruction and are a nociceptive stimulus, which might elevate intracranial pressure (ICP). This study tested the hypothesis that application of a hard collar is associated with an increase in ICP.

Bone graft substitutes in anterior cervical discectomy and fusion

Anterior cervical discectomy with fusion is a common surgical procedure for patients suffering pain and/or neurological deficits and unresponsive to conservative management. For decades, autologous bone grafted from the iliac crest has been used as a substrate for cervical arthrodesis. However patient dissatisfaction with donor site morbidity has led to the search for alternative techniques. We present a literature review examining the progress of available grafting options as assessed in human clinical trials, considering allograft-based, synthetic, factor- and cell-based technologies.

Technique, challenges and indications for percutaneous pedicle screw fixation

Minimally invasive techniques in spinal surgery are increasing in popularity due to numerous potential advantages, including reduced length of stay, blood loss and requirements for post-operative analgesia as well as earlier return to work. This review discusses guidelines for safe implantation of percutaneous pedicle screws using an image intensifier technique. As indications for percutaneous pedicle screw techniques expand, the nuances of the minimally invasive surgery technique will also expand. It is paramount that experienced surgeons share their collective knowledge to assist surgeons at their early attempts of these complex, and potentially dangerous, procedures. Technical challenges of percutaneous pedicle screw fixation techniques are also discussed including: small pedicle cannulation, percutaneous rod insertion for multilevel constructs, incision selection for multilevel constructs, changing direction with percutaneous pedicle screw placement, L5/S1 screw head proximity and sclerotic pedicles with difficult Jamshidi placement. We discuss potential indications for minimally invasive fusion techniques for complex spinal surgery and support these with descriptions of illustrative patients.

Lumbar interbody fusion: techniques, indications and comparison of interbody fusion options including PLIF, TLIF, MI-TLIF, OLIF/ATP, LLIF and ALIF.

Degenerative disc and facet joint disease of the lumbar spine is common in the ageing population, and is one of the most frequent causes of disability. Lumbar spondylosis may result in mechanical back pain, radicular and claudicant symptoms, reduced mobility and poor quality of life. Surgical interbody fusion of degenerative levels is an effective treatment option to stabilize the painful motion segment, and may provide indirect decompression of the neural elements, restore lordosis and correct deformity. The surgical options for interbody fusion of the lumbar spine include: posterior lumbar interbody fusion (PLIF), transforaminal lumbar interbody fusion (TLIF), minimally invasive transforaminal lumbar interbody fusion (MI-TLIF), oblique lumbar interbody fusion/anterior to psoas (OLIF/ATP), lateral lumbar interbody fusion (LLIF) and anterior lumbar interbody fusion (ALIF). The indications may include: discogenic/facetogenic low back pain, neurogenic claudication, radiculopathy due to foraminal stenosis, lumbar degenerative spinal deformity including symptomatic spondylolisthesis and degenerative scoliosis. In general, traditional posterior approaches are frequently used with acceptable fusion rates and low complication rates, however they are limited by thecal sac and nerve root retraction, along with iatrogenic injury to the paraspinal musculature and disruption of the posterior tension band. Minimally invasive (MIS) posterior approaches have evolved in an attempt to reduce approach related complications. Anterior approaches avoid the spinal canal, cauda equina and nerve roots, however have issues with approach related abdominal and vascular complications. In addition, lateral and OLIF techniques have potential risks to the lumbar plexus and psoas muscle. The present study aims firstly to comprehensively review the available literature and evidence for different lumbar interbody fusion (LIF) techniques. Secondly, we propose a set of recommendations and guidelines for the indications for interbody fusion options. Thirdly, this article provides a description of each approach, and illustrates the potential benefits and disadvantages of each technique with reference to indication and spine level performed.

Spine Interbody Implants: Material Selection and Modification, Functionalization and Bioactivation of Surfaces to Improve Osseointegration

The clinical outcome of lumbar spinal fusion is correlated with achievement of bony fusion. Improving interbody implant bone on‐growth and in‐growth may enhance fusion, limiting pseudoarthrosis, stress shielding, subsidence and implant failure. Polyetheretherketone (PEEK) and titanium (Ti) are commonly selected for interbody spacer construction. Although these materials have desirable biocompatibility and mechanical properties, they require further modification to support osseointegration. Reports of extensive research on this topic are available in biomaterial‐centric published reports; however, there are few clinical studies concerning surface modification of interbody spinal implants. The current article focuses on surface modifications aimed at fostering osseointegration from a clinicians point of view. Surface modification of Ti by creating rougher surfaces, modifying its surface topography (macro and nano), physical and chemical treatment and creating a porous material with high interconnectivity can improve its osseointegrative potential and bioactivity. Coating the surface with osteoconductive materials like hydroxyapatite (HA) can improve osseointegration. Because PEEK spacers are relatively inert, creating a composite by adding Ti or osteoconductive materials like HA can improve osseointegration. In addition, PEEK may be coated with Ti, effectively bio‐activating the coating.

Minimally invasive surgery compared to open spinal fusion for the treatment of degenerative lumbar spine pathologies

This clinical study prospectively compares the results of open surgery to minimally invasive fusion for degenerative lumbar spine pathologies. Eighty-two patients were studied (41 minimally invasive surgery [MIS] spinal fusion, 41 open surgical equivalent) under a single surgeon (R. J. Mobbs). The two groups were compared using the Oswestry Disability Index, the Short Form-12 version 1, the Visual Analogue Scale score, the Patient Satisfaction Index, length of hospital stay, time to mobilise, postoperative medication and complications. The MIS cohort was found to have significantly less postoperative pain, and to have met the expectations of a significantly greater proportion of patients than conventional open surgery. The patients who underwent the MIS approach also had significantly shorter length of stay, time to mobilisation, lower opioid use and total complication rates. In our study MIS provided similar efficacy to the conventional open technique, and proved to be superior with regard to patient satisfaction, length of hospital stay, time to mobilise and complication rates.

Lumbar discectomy and the diabetic patient: incidence and outcome.

Medical records of 363 patients who had a diagnosis of lumbar disc disease and were managed by a posterior approach lumbar discectomy over a 7 year period were reviewed: 33 patients had a preoperative diagnosis of diabetes, an incidence in this patient population of 9.1%. The results for these 33 patients who had a diagnosis of diabetes mellitus were compared with those of 33 age and sex matched nondiabetic (control) patients who had a similar operative approach. Twenty-five of the diabetic and 28 of t he control patients were available for long term follow up. The results were positive (good to excellent) for 24 of the 28 (86%) control patients and 15 of the 25 (60%) diabetic patients. Seven of the 25 (28%) diabetic patients had reoperation for recurrent disc herniation at the same level following the initial procedure compared with one of the 28 (3.5%) control patients.

Anterior cervical discectomy and fusion: analysis of surgical outcome with and without plating

The aim of this study is to analyse the differences in clinical and radiological outcome of anterior cervical discectomy and fusion for cervical degenerative disease, with and without the addition of an anterior cervical locking plate. Although disc arthoplasty is gaining popularity, the anterior cervical decompression and fusion procedure remains the gold standard. The outcome of 242 cases operated between 1991 to 1998 were analysed. Two groups of patients were operated on by the same surgeon. The only difference in technique between the two groups was the addition of an anterior cervical plate, with all other technical details matching, including the use of iliac crest autograft. The indications for surgery for both groups was identical. We made an attempt to study radiological fusion, clinical outcome and complications between the non-plated and plated groups. Our main finding is that the addition of an anterior plate reduces the number of poor clinical outcomes, but does not increase the number of excellent outcomes. Anterior discectomy and fusion with plating in our series had a significantly higher fusion rate; 98% fusion was noted in the plating group as compared to 93.5% in the non-plating group (Fishers exact test, p=0.029). Union was faster in the plated group with no significant increase in surgical complications. Although clinical outcomes were superior in the plated group for the radiculopathy cohort, excellent outcomes were not significantly higher as compared to the non-plated group. The non-plated group had a significantly higher rate of poor outcomes, with 10% of patients requiring revision surgery for non-union, kyphosis, graft extrusion and graft collapse with foraminal stenosis. 1.8% of the plated group required revision surgery.

Retrospective Computed Tomography Scan Analysis of Percutaneously Inserted Pedicle Screws for Posterior Transpedicular Stabilization of the Thoracic and Lumbar Spine : Accuracy and Complication Rates

Study Design. Retrospective clinical data analysis. Objective. To investigate the misplacement rate and related clinical complications of percutaneous pedicle screw insertion in the thoracic and lumbar spine. Summary of Background Data. Percutaneous insertion of cannulated pedicle screws has been developed as a minimally invasive alternative to the open technique during instrumented fusion procedures of the thoraco-lumbar spine. The reported rate of screw misplacement using open techniques is well described, however data is lacking on the exact failure rate of the percutaneous technique. Methods. A total of 424 percutaneously inserted pedicle screws from 2007 to 2010 were analyzed in 88 patients, from a single surgeon series (RJM). Axial reformatted computer tomographic images were examined by 2 independent observers and individual and consensus interpretation was obtained for each screw position. A simple grading system was used for assessment of screw accuracy—Grade 0: screw within cortex of pedicle; Grade 1: screw thread breach of wall of pedicle <2 mm; Grade 2: significant breach >2 mm with no neurological compromise; Grade 3: complication including pedicle fracture, anterior breach with neuro-vascular compromise, and lateral or medial breach with neurological sequelae. Results. The indications for percutaneous pedicle screw insertion include: degenerative (78%), trauma (13%), tumour (8%), and infection (1%). Pedicle screws were inserted into level T4 to S1. The most common levels performed include L4 and L5 with the most common indication for surgery being an L4/5 spondylolisthesis. 383 out of 424 screws (90.3%) were placed in the cortical shell of the pedicle (Grade 0). Forty-one screws (9.7%) were misplaced from T4 to S1. Of these, the majority were Grade 1 pedicle violations (24 screws; 5.7%), with 15 Grade 2 violations (3.5%) and 2 Grade 3 violations (0.5%). Of the 2 Grade 3 pedicle violations, both were pedicle fractures but only 1 had associated neurological deficit (L4 radiculopathy postoperatively). Conclusion. Percutaneous insertion of cannulated pedicle screws in the thoracic and lumbar spine is an acceptable technique with a low complication rate in experienced hands. The overall rate of perforation is below the higher rates reported in the literature for the open technique. Complication rates including pedicle fracture were low.

Death after late failure of endoscopic third ventriculostomy: A potential solution

OBJECTIVELate failure after successful third ventriculostomy is rare, and death caused by failure of a previously successful third ventriculostomy has been reported on four occasions. We describe a simple innovation that adds little morbidity and has the potential to reduce the advent of death after late failure of endoscopic third ventriculostomy. METHODSAfter endoscopic fenestration of the floor of the third ventricle, a ventricular catheter and subcutaneous reservoir are placed via the endoscope path. With acute blockage and neurological deterioration, cerebrospinal fluid can be removed via needle puncture of the reservoir until consultation with a neurosurgeon. RESULTSFrom 1979 to 2003, more than 240 endoscopic third ventriculostomies have been performed at our institution, with one death after late failure. The revised technique was devised after this death and has been performed on 21 patients to date. CONCLUSIONThe addition of a reservoir adds little time and morbidity to the procedure and offers the potential to sample cerebrospinal fluid, measure intracranial pressure, and reduce mortality associated with late failure of endoscopic third ventriculostomy.