C1-C2 transarticular screw fixation: technical aspects.

OBJECTIVE: I review posterior atlantoaxial fusion with transarticular screw fixation, including indications, complications, and operative technique, emphasizing my experience. METHODS: The indications for C1-C2 transarticular screw fixation include traumatic injuries to the atlantoaxial complex, instability resulting from inflammatory disease (rheumatoid arthritis), and congenital abnormalities (os odontoideum). All patients underwent stabilization using cannulated C1-C2 transfacetal screws by the method described by Magerl. Supplemental interspinous fusion with bicortical autologous iliac crest graft and titanium cable was used to restore the posterior tension band by use of the method described by Sonntag's group. Preoperatively, all patients underwent imaging with plain radiographs, magnetic resonance imaging, and axial computed tomography. Patients were maintained in a rigid cervical orthosis postoperatively. RESULTS: Measures used to improve safety and efficacy include patient positioning, fluoroscopic guidance, preoperative magnetic resonance imaging, axial computed tomography, and open reduction of C1-C2 subluxation before screw passage. In this series of 75 patients, fusion was obtained in 72 patients (96%). There were no instances of vertebral artery injury, errant screw placement, instrumentation failure, dural laceration, spinal cord injury, or hypoglossal nerve injury. CONCLUSION: C1-C2 transarticular screw fixation with a posterior tension band construct provides excellent fusion rates with few perioperative complications. Preoperative imaging and meticulous surgical technique improve outcomes.

Epidural lipomatosis simulating an epidural abscess: case report and literature review.

A case of epidural lipomatosis in a 49-year-old man presenting with paraparesis, midthoracic pain, and Staphylococcus aureus pneumonia is reported. The patient had been on low dose corticosteroid therapy for 7 years for rheumatoid arthritis. The clinical and myelographic findings suggested a diagnosis of epidural abscess, but the only abnormality discovered at operation was abundant fatty tissue in the dorsal epidural space significantly compressing the spinal cord, and this was partially removed. Postoperative neurological improvement suggested that the lipomatosis was responsible for the spinal cord compression and dysfunction. If this diagnosis had been suspected, it might have been confirmed by magnetic resonance imaging or postmyelography computed tomographic scanning. With such a diagnosis, an alternative treatment could have been to decrease the steroid dose, observe for clinical improvement, and perhaps avoid operation.

Gunshot wounds to the head: a perspective.

Craniocerebral gunshot wounds are a significant cause of injury and death in the United States. However, despite reports of occasional unexpectedly favorable outcome in surgically treated patients, these injuries have been viewed pessimistically and indeed have generally been excluded from modern studies of head injuries, which have concentrated on closed head injuries. A review of 143 victims of craniocerebral gunshot wounds admitted to Hermann Hospital, Houston, Texas, during a recent 30-month period confirmed that a few apparently neurologically devastated patients can be saved. A detailed analysis of these patients, including demographic details, general and neurological condition, anatomic injuries, laboratory findings, surgical care, neurological course, and neurological and functional outcome follows. The helpfulness of early resuscitation and appropriate criteria for surgery need to be studied using historic or randomized controls.

Pull-out strength of Caspar cervical screws.

Anterior cervical instrumentation as an adjunct to bone fusion has an important role in cervical spine surgery. Posterior vertebral body cortex purchase is strongly recommended in the use of the Caspar system, although few biomechanical data exist to validate this requirement. In this study, Caspar screws were placed in 43 human cadaveric cervical vertebral bodies, either putting them into the posterior vertebral cortex as identified radiographically or penetrating it by 2 mm as recommended in the literature. Pull-out tests were conducted with tension applied to a connected plate at 0.25 mm/s, and force-deformation data were obtained. Failure typically occurred with clean pull-out; in most instances, cancellous bone remained attached to screw threads. Mean load without posterior cortical purchase was 375 +/- 53 N; with penetration it was 411 +/- 70 N. These differences were nonsignificant. Average deformation to failure was 1.41 +/- 0.10 mm in the group without posterior cortical penetration. In the posterior penetration group, mean deformation was 1.56 +/- 0.16 mm. Again, differences were not significant. Posterior cortical penetration does not improve the pull-out strength of Caspar screws in an isolated vertebral body model, but other biomechanical studies need to be done before insertion methods are altered.

C1-C2 transarticular screw fixation for atlantoaxial instability: a 6-year experience.

OBJECTIVE: We review a 6-year, single-center experience using the technique of C1-C2 transarticular screw fixation for atlantoaxial instability in 75 consecutive operations. METHODS: The study group was composed of 43 men and 32 women, with a mean age of 44 years (range, 8-76 yr). Each patient had documented atlantoaxial instability. In 28 patients (37%), atlantoaxial instability was a result of trauma; in 22 patients, (29%), it was a result of rheumatoid arthritis; in 16 patients (21%), it was a result of prior surgery; and in 9 patients (12%), it was a result of congenital abnormalities. All patients underwent stabilization with C1-C2 transfacetal screws and a posterior interspinous construct. Nine patients had unilateral screws placed. Postoperatively, the patients were maintained in a rigid cervical orthosis for a mean of 11 weeks (range, 8-15 wk); five patients were immobilized with halo fixation for a mean of 13 weeks (range, 10-16 wk). The mean follow-up period was 2.4 years (range, 1-5.5 yr). RESULTS: Osseous fusion was documented in 72 patients (96%). There were no hardware failures; however, three patients developed pseudarthrosis. Two superficial wound infections (one at the graft site and one at the cervical incision site) required antibiotic therapy. Four patients had transient suboccipital hypesthesia. No instances of an errant screw, dural laceration, or injury to the vertebral artery, spinal cord, or hypoglossal nerve were noted. CONCLUSION: C1-C2 transarticular screw fixation supplemented with an interspinous construct yielded a 96% fusion rate, with a low incidence of complications. We attribute our successful outcomes to careful preoperative assessment and meticulous surgical technique.

Management of acute odontoid fractures with single-screw anterior fixation.

OBJECTIVE: Accepted management strategies for odontoid fractures include external immobilization and surgical stabilization using anterior or posterior approaches. Displaced Type II fractures and rostral Type III fractures are at high risk for nonunion. Anterior fixation of odontoid fractures with a single cortical lag screw is a relatively new technique that combines rigid internal stabilization with preservation of intrinsic C1-C2 motion. We retrospectively reviewed our series of 26 consecutive patients who underwent odontoid screw fixation, to further define the safety and efficacy of the technique. METHODS: During a 5-year period, 26 patients presented with acute traumatic Type II odontoid fractures. Ten patients were female and 16 were male, with a mean age of 35 years. All patients underwent anterior odontoid screw fixation by the senior surgeon (RWH), within a mean of 3 days after injury. All patients were postoperatively maintained in external orthoses, for a mean of 7.2 weeks, and were monitored with serial clinical and radiographic examinations. RESULTS: With a mean follow-up period of 30 months, radiographic fusion was documented for 25 of 26 patients (96%). No complications related to the surgical approach were identified, and all patients remained in neurologically stable condition. Two complications (8%) were related to the instrumentation; one patient required external immobilization because of suboptimal screw placement, and one patient required posterior atlantoaxial arthrodesis because of inadequate fracture reduction. CONCLUSION: Single-screw anterior odontoid fixation was associated with a relatively low complication rate and a high fusion rate in this study. We think that this should be the preferred treatment method for acute Type II odontoid fractures.

Type I fractures of the odontoid process: implications for atlanto-occipital instability. Case report.

Only four cases of Type I odontoid fracture have been previously described in the English literature. Most authors consider this lesion to be stable, although the mechanism(s) of injury has not been clearly elucidated. A case of Type I odontoid fracture in association with atlanto-occipital and atlantoaxial dislocation resulting in death is presented. The normal ligamentous anatomy is reviewed and proposed mechanisms for this injury are discussed. The radiographic features of all reported cases of this type are reviewed. It is proposed that the Type I odontoid fracture is a likely manifestation of atlanto-occipital instability and rarely occurs as an isolated or stable injury.

Occipital neuralgia secondary to hypermobile posterior arch of atlas. Case report.

The authors report on the management of occipital neuralgia secondary to an abnormality of the atlas in which the posterior arch was separated by a fibrous band from the lateral masses, resulting in C-2 nerve root compression. The causes and treatments of occipital neuralgia as well as the development of the atlas are reviewed.

Transpedicular screw-rod fixation of the lumbar spine: operative technique and outcome in 104 cases.

A total of 104 patients underwent transpedicular spinal instrumentation using the Cotrel-Dubousset (71 cases) or the Texas Scottish Rite Hospital (33) screw-rod system. Surgery was performed for lumbar vertebral column instability secondary to fractures (28 cases), spondylolisthesis (29), tumors (four), vertebral osteomyelitis (two), or postoperative causes (41). Pseudoarthrodesis due to failure of a prior fusion was present in 37 cases. The 55 men and 49 women (mean age 47 years, range 18 to 87 years) all presented with severe back pain. Signs or symptoms of neural compression were noted in 96 patients. Surgery consisted of neural decompression, internal fixation, and autogenous iliac bone grafting. Spondylolistheses were fused in situ, without reduction; otherwise, major spinal deformities were corrected. A total of 516 pedicle screws were placed. The mean extent of fusion was 2.7 motion segments (range one to six motion segments). A 96% fusion rate was obtained with a mean follow-up period of 20 months. There were no operative deaths. Major complications included one spinal epidural hematoma, three isolated nerve root deficits (two transient, one permanent), and three wound infections (two deep, one superficial). Instrument failure eventually developed in 18 patients; nine were asymptomatic with a solid fusion and did not require further treatment and the other nine were symptomatic or had a pseudoarthrosis and required operative revision. Pedicle screw-rod fixation offers biomechanical advantages compared to other forms of internal fixation for the lumbar spine. It enables short-segment fixation with preservation of lumbar lordosis and adjacent normal motion segments. This technique provides a highly successful method to obtain arthrodesis, even with prior pseudoarthrosis.

Threaded cortical bone dowels for lumbar interbody fusion: over 1-year mean follow up in 28 patients.

OBJECT: The authors retrospectively reviewed a series of 35 patients with mechanical low-back or one- to two-level discogenic pain; the patients underwent lumbar interbody fusion in which threaded cortical bone dowels (TCBDs) were placed to treat degenerative disc disease. The purpose of the study was to delineate fusion rates and outcome data in this series of patients. METHODS: The series was composed of 18 women and 17 men whose mean age was 46 years (range 17-76 years). There were nine active cigarette smokers. All patients presented with symptoms consistent with mechanical low-back or discogenic pain, and magnetic resonance imaging revealed degenerative changes related to disc collapse at one or two vertebral levels. For placement of the TCBDs, 23 patients underwent posterior lumbar interbody fusion (PLIF), whereas 12 patients underwent anterior lumbar interbody fusion (ALIF). In all except one patient undergoing PLIF, pedicle screw and rod constructs were used without posterolateral fusion. In all patients undergoing ALIF except one, TCBDs were used as stand-alone devices without supplemental fixation. At follow up the success of fusion was determined by static lumbar radiography and/or computerized tomography scanning. The degree of lumbar lordosis at the diseased level was measured immediately postoperatively and compared with that documented on follow-up radiological studies. Outcomes were assessed using a modified Prolo Scale. Excellent and good outcomes were considered satisfactory, and fair or poor outcomes were considered unsatisfactory. In 28 patients (eight ALIF and 20 PLIF) radiological and clinical follow-up data were considered adequate. The mean follow-up duration was 12.3 months. Overall satisfactory outcome was 60%; 70% satisfactory outcome was noted in PLIF patients and 38% in ALIF patients. Osseous fusion was present in 95% of the patients in the PLIF group and in 13% of those in the ALIF group. Complications included one L-5 nerve root injury and two postoperative wound infections, all in patients who underwent PLIF; in an ALIF patient lateral breakout of one implant occurred at 8 months postoperatively. CONCLUSIONS: Analysis of the mean 12.3 month follow-up data indicates that there is a dramatically higher fusion rate in PLIF compared with ALIF procedures when TCBDs are used. The authors believe that it is important to note that in all the PLIF procedures except one, supplemental pedicle screw/rod constructs were used, whereas in ALIF procedures no supplemental fixation was performed. The results thus suggest that TCBDs are best used in PLIF in conjunction with pedicle screw and rod constructs.

Calcifying pseudoneoplasms of the spine with myelopathy. Report of two cases.

The authors describe two cases of calcifying pseudoneoplasms, rare degenerative lesions that mimic tumor or infection. One case involved the cervical spine and the second the thoracic spine. Both patients experienced progressive myelopathy from extradural compression of the spinal cord. The radiological evaluation, pathological findings in the lesions, treatment, and follow up are described. Total or subtotal excision can relieve symptoms and prevent recurrence of this lesion.

Single-stage anterior-posterior decompression and stabilization for complex cervical spine disorders.

OBJECT: To evaluate the applicability and safety of single-stage combined anterior-posterior decompression and fusion for complex cervical spine disorders, the authors retrospectively reviewed 72 consecutive procedures of this type performed using a uniform technique at a single center. METHODS: The indications for decompression and stabilization included: postlaminectomy kyphosis (15 patients), trauma (19 patients), spondylosis and congenital stenosis (32 patients), and ossification of the posterior longitudinal ligament (six patients). All patients underwent anterior cervical corpectomies in which allograft fibula and plates were placed, with 89% of patients undergoing two- or three-level procedures (range one-four levels). Lateral mass plating with autograft (morselized iliac crest) fusion was performed in all patients while the same anesthetic agent was still in effect. A hard cervical collar was used postoperatively in all patients (mean 13 weeks). All patients were followed for a minimum of 2 years (mean 29 months). Fusion was determined to be successful in all 72 patients (100%). Although the short-term morbidity rate reached 32%, the significant long-term morbidity rate was only 5%. At the 2-year follow-up examination, anterior cervical plate dislodgment was seen in one patient, and 16 of the 516 lateral mass screws implanted were observed to have partially backed out. However, there were no cases of nerve root injury, strut graft extrusion, or anterior plate or screw fracture. There were no clinically significant hardware complications and no patient required repeated operation. CONCLUSIONS: The combined single-stage anterior-posterior decompression, reconstruction, and instrumentation procedure represents a viable option in the treatment of a select group of patients with complex cervical spinal disorders. The technique provides immediate rigid stabilization of the cervical spine, prevents anterior plate failure or strut graft extrusion, and eliminates the need for halo immobilization postoperatively. Furthermore, a higher rate of fusion is achieved with this combined approach than with the anterior approach alone.

Treatment of degenerative cervical disc disease.

The different clinical presentations and treatment options available to treat neck pain from degenerative disc disease have been discussed. With proper patient selection, good correlation between clinical and radiographic findings, and selecting the correct procedure for each patient, surgical treatment of cervical radiculopathy and myelopathy can be one of the most gratifying operations performed in neurosurgery.

Lumbar and lumbosacral fusions using Cotrel-Dubousset pedicle screws and rods.

The first 50 consecutive patients stabilized with Cotrel-Dubousset rods for lumbar or lumbosacral fusions were followed for an average of 2 years. The occurrence of fusion, maintenance of alignment, and rate of hardware complications were examined. There were 28 men and 22 women, ages 18-87 years, and 133 vertebral levels. Twenty-nine sets of 5-mm, and 21 pairs of 7-mm, rods were placed. Two hundred and sixty-eight pedicle screws were used. Forty-eight out of 50 (96%) patients demonstrated successful arthrodesis after their initial procedure. One pedicle screw became separated from the rod. No rods migrated or broke. Seven (2.6%) pedicle screws bent and 3 (1%) broke. Large and small diameter Cotrel-Dubousset rods allowed short segment lumbar and lumbosacral fusion with a high degree of reliability.

Anterior cervical discectomy with freeze-dried fibula allograft. Overview of 317 cases and literature review.

STUDY DESIGN: A retrospective review of 317 patients to determine the efficacy of allogeneic fibula arthrodesis after anterior cervical discectomy. OBJECTIVE: To examine the efficacy of allogeneic fibula as an alternative fusion substrate after anterior cervical discectomy, and to determine the effects of cigarette smoking on the healing of fibula allografts. SUMMARY OF BACKGROUND DATA: The use of autogeneic iliac crest is associated with graft harvest complications in up to 20% of patients. Most studies reporting on the use of allogeneic iliac crest cite a high collapse rate. Few studies exist that note the efficacy of allogeneic fibula in this procedure and the effects of cigarette smoking on fusion rate. METHODS: From 1988 to 1993, 317 patients underwent grafting by the Smith-Robinson technique with allogeneic fibula after anterior cervical discectomy. Patients who described themselves as habitual cigarette smokers or who smoked during the perioperative or postoperative period were categorized as smokers. All patients were immobilized in a rigid cervical orthosis (Philadelphia collar) for at least 10 weeks postoperatively. RESULTS: A minimum of 2 years follow-up was achieved in 289 patients. In all, 162 men and 127 women had a total of 311 levels grafted, and the mean follow-up period was 33 months (range, 24 to 51 months). Of patients who received allogeneic fibula at one level, 90% (242/269) achieved radiologic fusion. The fusion rate was 92% (182/198) among nonsmokers compared with 85% (60/71) among smokers (not a statistically significant difference; P = 0.120). After two-level procedures, 72% (13/18) of the patients showed fusion. The fusion rate was 50% (2/4) among smokers compared with 79% (11/14) among nonsmokers (P = 0.53). When one-level arthrodesis (90%) was compared with two-level arthrodesis (72%), the difference approached statistical significance (P = 0.054). Neither of the two patients, both nonsmokers, who received grafts at three levels achieved fusion. There were no infections, and no grafts collapsed. Two grafts extruded (0.6%), but these were partial and did not require reoperation. Both patients fused and constituted the only patients with more than 10 degrees of angulation in the series. Graft subsidence occurred in 5% (17/311) of the grafts, mostly in the beginning of the series, and was not problematic. This phenomenon was thought to have been caused by overaggressive removal of the cortical endplate. CONCLUSION: Allogeneic fibula is an effective substrate for use in achieving fusion after anterior cervical discectomy. Maximal results are achieved with its use at one level in nonsmokers. Cigarette smoking decreased the fusion rate with allogeneic fibula in the anterior cervical spine, but not by a statistically significant amount.

Instrumentation and fusion for discogenic disease of the lumbosacral spine.

A classification of lumbosacral discogenic pain is presented. Focus is placed on the pathophysiology, radiographic and clinical criteria, and role of fusion on the treatment of degenerative disc disease and segmental instability. Adjuncts, determinants, and techniques of fusion are discussed. Instrumentation systems, most applicable to the lumbosacral spine, are reviewed.

Surgical Interbody Research Group--radiographic assessment of interbody fusion devices: fusion criteria for anterior lumbar interbody surgery.

The authors present their radiographic criteria for assessing fusion of the lumbar spine after anterior interbody fusion with intradiscal implants. These criteria include the assessment of plain radiographs, dynamic motion radiographs, and thin-cut computerized tomography scans. Fusion within the instrumented spinal motion segment can be determined using radiographic evaluation to assess spinal alignment on sequential examinations, angular and translational changes on dynamic motion studies, and device-host interface, and to identify new bone formation and bone remodeling. Finally, to aid the clinician in assessing fusion, the authors describe the five zones of fusion within the intervertebral disc space.

Management of acute odontoid fractures: operative techniques and complication avoidance.

In this article the authors describe the management of Type II odontoid fractures with special attention to operative technique and avoidance of complication. Anterior odontoid screw fixation is a procedure the authors have performed over the last 8 years in cases with acute Type II and rostral Type III odontoid fractures. In cases of Chronic Type II odontoid fractures and in patients with transverse ligament disruption, the authors prefer to undertake posterior transarticular facet screw fixation supplemented by bone graft and interspinous C1-2 wiring. The technical aspects of these procedures are described with a focus on operative nuances. Selection criteria and techniques that the authors have refined over the years have helped them to optimize success rates and minimize complications.

Bone morphogenetic protein in spinal fusion: overview and clinical update.

The widespread use of fusion procedures in the management of spinal disorders has led investigators to explore the use of growth and differentiation factors in such procedures. As an adjuvant to allograft bone or as a replacement for harvested autograft, bone morphogenetic proteins (BMPs) appear to improve fusion rates after spinal arthrodesis in both animal models and humans, while reducing the donor-site morbidity previously associated with such procedures. The use of recombinant genetic technology in the production of BMP has improved the efficiency, cost effectiveness, and safety of producing and using such materials. Recombinant human BMP-2 (rhBMP-2), as one of the first factors identified in the process of endochondral bone formation, has been extensively researched over the past decade. The efficacy and dose profile of this differentiation factor in the context of various carrier substrates has been investigated. Based on the encouraging results of preliminary studies, the future role of rhBMP-2 may lie in its replacement of autologous bone grafting and, consequently, the reduced need for instrumented fixation, while concurrently improving overall fusion rates. The authors provide an overview of BMP and review its use in clinical and laboratory settings.

Laparoscopic anterior lumbar interbody fusion. Technical note.

In recent years, there has been an unprecedented increase in the number of patients undergoing treatment with interbody fusion devices for degenerative disease of the lumbar spine. These devices can be placed either anteriorly or posteriorly. With the advent of minimally invasive surgery and the increasing ability of general surgeons to perform transperitoneal procedures laparoscopically, a new laparoscopic technique has been developed for placing lumbar interbody fusion devices. Although this procedure has some advantages over posterior lumbar interbody fusion, it is not without significant risk, and the learning curve is steep. The authors review a series of 32 consecutive patients who underwent single-level laparoscopic anterior lumbar interbody fusion at L4-5 or L5-S1 over a 2-year period for the treatment of single-level lumbar degenerative disease. In this report they review the technical aspects of the procedure and the important lessons they have learned through their early experience with this technique.