John M. Beiner

Radiographic analysis of transforaminal lumbar interbody fusion for the treatment of adult isthmic spondylolisthesis.

The radiographs of 35 consecutive adult patients with isthmic spondylolisthesis who underwent a transforaminal lumbar interbody fusion (TLIF) with one or two Brantigan carbon fiber cages and pedicle screw instrumentation were evaluated. Anterolisthesis, disk space height, and slip angle were measured in preoperative and postoperative standing neutral radiographs. Anterolisthesis was reduced and disk space height was increased with the TLIF procedure. Average slip angle, however, was not significantly altered. The restoration of lordosis across the listhetic disk space correlated with a more anterior placement of the interbody cage within the disk space. The TLIF technique, performed with the Brantigan cage and pedicle screw instrumentation, appears to be able to restore disk height and reduce forward translation in patients with isthmic spondylolisthesis, but improvement in sagittal alignment is dependent upon anterior placement of the interbody device.

Osteogenic potential of adult human stem cells of the lumbar vertebral body and the iliac crest.

Study Design. Marrow was aspirated from the vertebral body (VB) and iliac crest (IC) of patients undergoing lumbar spinal surgery, following an approved protocol. Progenitor cells were isolated using standard culture conditions and their osteogenic potential evaluated. Objective. To evaluate the osteogenic potential of mesenchymal stem cells (MSCs) isolated from the bone marrow of the human VB. Summary of Background Data. IC marrow grafting during cervical discectomy and fusion procedure is associated with donor site morbidity. Since the VB contains marrow cells, it may be possible to circumvent this problem by using this tissue for osseous graft supplementation. However, there is paucity of information concerning the osteogenic potential of non-IC-derived progenitor cells. Herein, we address this issue. Methods. Marrow samples from VB of patients undergoing lumbar spinal surgery were collected; marrow was also harvested from the IC. Progenitor cells were isolated and the number of colony forming unit-fibroblastic (CFU-F) determined. The osteogenic potential of the cells was characterized using biochemical and molecular biology techniques. Results. Both the VB and IC marrow generated small, medium, and large sized CFU-F. Higher numbers of CFU-F were obtained from the VB marrow than the IC (P < 0.05). Progenitor cells from both anatomic sites expressed comparable levels of CD166, CD105, CD49a, and CD63. Moreover, progenitor cells from the VB exhibited an increased level of alkaline phosphatase activity. MSCs of the VB and the IC displayed similar levels of expression of Runx-2, collagen Type I, CD44, ALCAM, and ostecalcin. The level of expression of bone sialoprotein was higher in MSC from the IC than the VB. VB and IC cells mineralized their extracellular matrix to a similar extent. Conclusions. Our studies show that CFU-F frequency is higher in the marrow of the VB than the IC. Progenitor cells isolated from both sites respond in a similar manner to an osteogenic stimulus and express common immunophenotypes. Based on these findings, we propose that progenitor cells from the lumbar vertebral marrow would be suitable candidate for osseous graft supplementation in spinal fusion procedures. Studies must now be conducted using animal models to ascertain if cells of the VB are as effective as those of the IC for the fusion applications.

Similarities and differences in the treatment of spine trauma between surgical specialties and location of practice.

Study Design. Questionnaires administered to practicing orthopedic and neurosurgical spine surgeons from various regions of the United States and abroad. Objectives. To determine similarities and differences in the treatment of spinal trauma. Summary of Background Data. Spinal trauma is generally referred to subspecialists of orthopedic or neurosurgical training. Prior studies have suggested that there is significant variability in the management of such injuries. Methods. Questionnaires based on eight clinical scenarios of commonly encountered cervical, thoracic, and lumbar injuries were administered to 35 experienced spinal surgeons. Surgeons completed profile information and answered approximately one dozen questions for each case. Data were analyzed with SPSS software to determine the levels of agreement and characteristics ofrespondents that might account for a lack of agreement on particular aspects of management. Results. Of the 35 surgeons completing the questionnaire, 63% were orthopedists, 37% were neurosurgeons, and 80% had been in practice for more than 5 years. Considerable agreement was found in the majority of clinical decisions, including whether or not to operate and the timing of surgery. Of the differences noted, neurosurgeons were more likely to obtain a MRI, and orthopedists were more likely to use autograft as a sole graft material. Physicians from abroad were, in general, more likely to operate and to use an anterior approach during surgery than physicians from the northeastern United States. Conclusions. More commonalities were identified in the management of spinal trauma than previously reported. When found, variability in opinion was related to professional and regional differences. Spine 2004;29:685–696

The use of rigid internal fixation in the surgical management of cervical spondylosis.

IN THE SURGICAL management of cervical spondylosis, the application of rigid internal fixation can enhance the immediate stability of the cervical spine. The sophistication of such internal fixation systems and the indications for their use are continuously evolving. A sound understanding of regional anatomy, biomechanics, and kinematics within the cervical spine is essential for the safe and effective application of internal fixation. Numerous options currently exist for anterior cervical plating systems; some lock the screws to the plate rigidly (constrained), whereas others allow for some rotational or translational motion between the screw and plate (semiconstrained). The role of anterior fixation in single and multilevel fusions is still the subject of some controversy. Long anterior cervical reconstructions may require additional posterior fixation to reliably promote fusion. Rigid fixation in the posterior cervical spine can be achieved with lateral mass screws or pedicle screws. Although lateral mass screws provide excellent fixation within the subaxial cervical spine, the regional anatomy of C2 and C7 often make it difficult to place such screws, and pedicle screws at these levels are advocated. Pedicle screws achieve fixation into both the anterior and posterior column and are arguably the most stable form of rigid internal fixation within the cervical spine. Familiarity with these internal fixation techniques can be an extremely valuable tool for the spine surgeon managing these degenerative disorders of the cervical spine.

Morphologic evaluation of cervical spine anatomy with computed tomography: anterior cervical plate fixation considerations.

The computed tomography (CT) studies of the cervical spine from 50 males and 50 females were reviewed to provide morphometric data on a variety of anatomic parameters relevant to anterior cervical reconstruction and fixation. Measurements were made of the vertebral body width and midsagittal anteroposterior (AP) diameter and the distance between the medial borders of the longus coli muscles. Distances between adjacent endplates were also measured, both at their midpoint and at the anterior margin. Widths of the vertebral bodies measure 24.6 ± 2.4 and 23.0 ± 2.4 mm in males and females, respectively, with the narrowest measuring 17 and 14, respectively. The average midsagittal AP diameter of each vertebral body in males was approximately 17–18 mm, with the smallest AP diameter measured to be 13 mm. The average midsagittal AP diameter of each vertebral body in females was approximately 15–16 mm, with the smallest being 10 mm. CT scanning provides excellent osseous detail for the measurement of such parameters, and with its widespread use in the evaluation of cervical disorders, large numbers of patients can be reviewed.

Indications, techniques, and outcomes of posterior surgery for chronic low back pain

This article summarizes a number of issues surrounding the diagnosis, indications, and techniques of posterior lumbar spine surgery for chronic low back pain. It would not be entirely unjustified for a spine surgeon to adhere to a totally avoidant approach to chronic low back pain, rationalized by a reasonably legitimate nihilism regarding the presently available means of diagnosing and surgically managing low back pain [64]. Judging by the number of lumbar fusions performed in North America and the tremendous intellectual and financial investment currently being made in technologies to enhance spinal fusion, such an approach is evidently not achieving wide-spread acceptance on this continent. A rationale approach is therefore required for the many low back pain sufferers with degenerative disk disease who arrive in the office having exhausted almost every imaginable form of nonoperative therapy. Every effort should be made to establish a pathoanatomic etiology of the back pain with a combination of diagnostic modalities. Surgical intervention should be approached cautiously and only after extensive dialog with the patient to establish realistic goals and expectations. Posteriorly performed interbody fusion procedures may provide a high fusion rate and satisfactory clinical outcomes for this challenging problem, although further research is necessary to determine more conclusively the role of surgery and the relative effectiveness of the various arthrodesis techniques.

An aneurysmal bone cyst in the cervical spine of a 10-year-old girl: a case report.

Study Design. An aneurysmal bone cyst in the neural arch of the fourth cervical vertebra of a 10-year-old girl is reported, along with a brief review of the literature on the topic. Objective. To report the presentation and diagnosis of this disorder along with a discussion of the major pitfalls of treatment. Summary of Background Data. An aneurysmal bone cyst occurs commonly in the second decade, with a predilection for the lumbar spine. With occurrence in the neural arch of a cervical vertebra, the potential for instability following surgical excision is high. Methods. A 10-year-old white female presented with neck pain of 3 months’ duration. Diagnostic imaging revealed an expansile lytic lesion in the spinous process and lamina of the fourth cervical vertebra. Surgical treatment consisted of excisional biopsy and a segmental instrumented posterior fusion from C3–C5. The histopathology was consistent with an aneurysmal bone cyst. Results. Surgical excision consisting of laminectomy and instrumented segmental fusion provided a good clinical result, and minimized the risk and degree of the 2 most common complications: recurrence of the tumor; and postlaminectomy kyphosis, a frequent occurrence in the pediatric population. Conclusions. In pediatric patients who develop a bone tumor of the posterior elements of the cervical spine, careful clinical and radiologic evaluation is necessary to narrow the differential diagnosis. In most cases, a complete excision should be performed if possible. The risk of postlaminectomy kyphosis is high in the pediatric age population. As such, a fusion should be considered whenever a laminectomy is performed in the immature cervical spine. Risk factors for kyphosis include a high cervical level, multiple laminectomy levels, and postoperative irradiation.

Bone Graft Alternatives for Spinal Fusion

Bone grafting to achieve fusion is frequently performed in spinal surgery. Autograft is the gold standard bone graft material. However, due to limitations of supply and morbidity associated with the harvest of autograft, alternatives are being considered. Osteoconductive matrices, such as allograft, calcium or ceramic preparations are one such class of potential bone graft alternatives, but generally they lack osteoinductive properties. Recent attention has focused on osteoinductive materials such as demineralised bone matrix, recombinant bone morphogenetic proteins and bone marrow aspirates or blood product concentrates. These products may be combined with osteoconductive carriers and are clearly finding a place in the clinical arena.

Evaluation of a Novel Pedicle Probe for the Placement of Thoracic and Lumbosacral Pedicle Screws

Background: Pedicle screw instrumentation is common in the lumbar spine and is gaining acceptance in the thoracic spine. The pedicle is generally cannulated with a gearshift probe or curette. SafePath (Mekanika, Boca Raton, FL) is an alternative pedicle probe designed for pedicle cannulation. This is a blunt-tipped, nonaggressive drill that seeks the cancellous portion of the pedicle. Objective: The objective of this study was to evaluate the accuracy of this device in comparison with techniques commonly used for pedicle cannulation. Methods: Four osteoligamentous fresh-frozen thoracic to sacral cadaveric spines were studied. The pedicles of one side of each cadaver were cannulated with the SafePath device. The contralateral pedicles were cannulated with either a gearshift probe or a 3-0 cervical curette. The accuracy of pedicle probe placement was evaluated by radiography, computed tomography (CT) scan, and direct observation via dissection. Results: By direct observation, 51 of 128 pedicles were violated (40%). There were not significant differences between the results obtained with the gearshift probe or curette; there were 2 of 22 lumbosacral violations (9%) and 14 of 45 thoracic violations (33%). With the SafePath device, there were 0 of 22 lumbosacral violations (0%) and 34 of 45 thoracic violations (76%). SafePath performed significantly better in the lumbar spine and significantly worse in the thoracic spine. The accuracy for determining pedicle violation was 88% for radiography and 85% for CT. Conclusions: The results of this in vitro study suggest that the SafePath device may represent an alternative to traditional pedicle cannulation techniques in the lumbosacral spine. However, the opposite is true in the thoracic spine, where SafePath performed significantly worse than traditional techniques.

Lumbar decompressive surgery

Traditionally, decompressive surgery of the lumbar spine has produced successful results in terms of relieving lower extremity radicular pain. In the setting of degenerative disk disease, decompressive surgery is usually performed for lumbar disk herniation or lumbar spinal stenosis in patients with persistent lumbar radiculopathy or neurogenic claudication. When localized to a single nerve root secondary to herniated nucleus pulposus or isolated canal stenosis, decompression is most efficiently achieved with microscopic or minimally invasive techniques. These procedures are the topic of another article in this journal. In this article, we will review the clinical presentation of patients with multilevel lumbar radiculopathy with or without neurogenic claudication, and describe operative techniques for decompression of their underlying degenerative lumbar spinal stenosis.