Interlaminar Clamps Research Articles

Computed Tomography-Based Feasibility Study of C1 Posterior Arch Crisscrossing Screw Fixation.

Study DesignRetrospective radiographic analysis.PurposePosterior fixation of C1 using screws is the most popular technique among the various methods for C1 stabilization, but it places the surrounding neurovascular structures at risk. Approximately 20% of the population has an anomalous groove for the vertebral artery; therefore, salvage methods are necessary. Therefore, we analyzed the feasibility of a newer C1 posterior arch crisscrossing screw fixation technique and studied its feasibility in the Indian population on the basis of the anatomy of the C1 posterior arch.Overview of LiteratureMultiple techniques have been described for C1–C2 fixation, such as wiring techniques, interlaminar clamps, transarticular screws, screw-plate/screw-rod system fixation, and hook-screw system fixation techniques, to provide rigid C1–C2 stability. However, although C1 fixation has evolved with time, it is not complication-free.MethodsA 100 computed tomography (CT) scans of cervical spines with 1 mm slice thickness in the axial and sagittal sections obtained were randomly selected for the evaluation. Atlantoaxial anomalies due to trauma, deformities, infections, and tumors were excluded. All the images were measured for height of the posterior tubercle, width of the posterior arch, and length of the screw, and the screw projection angle was calculated. Demographic data were collected for all the subjects.ResultsOut of the 88 CT scans analyzed, the mean height of the posterior tubercle was 7.4 mm, wherein 84.09% exceeded 7 mm, and the width of the posterior tubercle was 5.4 mm, wherein 88.6% (n=78) had posterior arch width >3.5 mm. A total of 13.6% (n=12) vertebrae were not suitable for screw placement, whereas 75% (n=66) vertebrae could accommodate 3.5×15 mm or longer screws. The screw projection angles ranged from 11.2° to 35° on the right and from 15.6° to 38.2° on the left.ConclusionsC1 posterior arch screw fixation is a feasible and safe method because it poses little risk of injury to the surrounding neurovascular structures.

Morphometric analyses of atlas vertebrae-A cross sectional study

Introduction: Knowledge about morphometric measurements related to atlas vertebra are important for neurologists, neurosurgeons and head and neck surgeons who deal with traumatic or non-traumatic conditions which may lead to altanto-axial and atlanto- occipital instability. The aim of the present study was to assess the various parameters on the atlas vertebra which can help to determine the safe sites for the different surgical approaches. Materials and Methods: Study was carried out on 50 dry south Indian adult human atlas vertebrae of unknown sex which were collected from the department of anatomy. Eleven parameters were measured for each atlas using a digital vernier caliper. Results: Range, mean and standard deviations were measured and recorded and bilateral symmetry was observed. Conclusion: The parameters measured in the present study may help surgeons in avoiding and reducing complications such as vertebral artery injury, spinal cord injury during the surgical corrections of atlanto axial or atlanto occipital instability. Keywords: Atlas, vertebrae, Atlanto-axial, Atlanto-occipital, Interlaminar clamps

Treatment of Subaxial Cervical Spinal Injuries

SUBAXIAL CERVICAL FACET DISLOCATION INJURIES: Standards There is insufficient evidence to recommend treatment standards. Guidelines There is insufficient evidence to recommend treatment guidelines. Options Closed or open reduction of subaxial cervical facet dislocation injuries is recommended. Treatment of subaxial cervical facet dislocation injuries with rigid external immobilization, anterior arthrodesis with plate fixation, or posterior arthrodesis with plate or rod or interlaminar clamp fixation is recommended. Treatment of subaxial cervical facet dislocation injuries with prolonged bedrest in traction is recommended if more contemporary treatment options are not available. SUBAXIAL CERVICAL INJURIES EXCLUDING FACET DISLOCATION INJURIES: Standards There is insufficient evidence to recommend treatment standards. Guidelines There is insufficient evidence to recommend treatment guidelines. Options Closed or open reduction of subluxations or displaced subaxial cervical spinal fractures is recommended. Treatment of subaxial cervical spinal injuries with external immobilization, anterior arthrodesis with plate fixation, or posterior arthrodesis with plate or rod fixation is recommended.

C1-C2 Fusion: Promoting Stability, Reducing Morbidity

he surgical treatment of atlantoaxial instability has been evolving for more than 100 years. The first report was T a case presentation in 1910, by Mixter and Osgood (30), who described using heavy silk thread to secure the posterior arch of the atlas to the spinous process of the axis. The next few decades were associated with multiple advances, including approaches using dorsal cervical wiring techniques. These included the Gallie technique (13, 16, 27), the Brooks-Jenkins technique (5), and the technique of Dickman and Sonntag (9) and Dickman et al. (10). Nonwiring techniques included interlaminar clamps (21), the Magerl transarticular screw technique (26), plate and screw techniques (17, 18), rod-cantilever techniques (19, 33, 40), translaminar screw techniques (25, 42, 43), and a variety of other strategies (28, 32). Although the approaches and indications vary, the fusion rates for these procedures have been observed to be as high as 90%e100% (2, 9, 12, 28).

Spine Instrumentation: Assessment of Morbidity Related to 250 Cases

Study design: A retrospective review of the morbidity associated with 250 consecutive cases of spinal instrumentation carried out in a neurosurgical spine unit. Objectives: To examine associated risk factors and results of treatment of those patients who sustained morbidity as a result of spinal instrumentation. Methods: The case records and imaging of all patients who had undergone spinal instrumentation at any level for any pathology were studied for morbidity related to the instrumentation used. They were followed up between 3 months to 8 years. Results: Over an 8-year period 250 consecutive patients underwent spinal instrumentation and fusion performed by the senior author (RP). These included those at the cervical (171), thoracic (34), and the lumbar (45) spinal levels. The indications were for trauma, degenerative changes, tumours, tuberculosis and congenital anomalies. The average follow up period was 1.1 years (3 months - 8 years). Of the 250 cases there was neurological deterioration observed in 6, in 4 there was root pain which recovered following removal of the pedicle screws. An intra op drop in SSEP was present in one patient which improved after removal of sub laminar wires and did not manifest as neurological deterioration post-op. There was an increased spasticity in 2 patients with Inter laminar clamps, who recovered following their removal. Conclusions: In experienced hands the neurological complications related to instrumentation is low. The infection rate can be kept to a minimum with meticulous technique. However its use should be confined to cases where clearly indicated.

THE STABILIZING EFFECT OF POSTERIOR FIXATIONS IN A DESTABILIZED ATLANTOAXIAL COMPLEX MODEL IN CANINES

Purpose: This study was conducted to evaluate the kinematic responses and the restorative effectiveness of three posterior fixations in a canine atlantoaxial ( C1-2) complex model.Methods: Nine canine ligamentous C1-2complexes were non-destructively tested in an intact condition, after ligamentous destabilization, and after bilateral stabilization with each of three posterior fixation methods: (1) Halifax inter-laminar clamps; (2) sub-laminar wiring; and (3) individual fixation of the C1lateral mass and the C2pedicle with screws and plates. Specimens were subjected to a relevantly applied loads through a loading frame rigidly attached to the C1. Two sets of three markers was separately attached to the mounting jigs of the C1and the C2to record the spatial locations after each loading step with a Vicron 370 system. The load-deformation data were analyzed.Results: Under a realistic loading paradigm, destabilized canine C1-2complex had 3-dimensional motion ranges highly consistent with the corresponding values observed in destabilized cadaveric human C1-2complex following a non-destructive loading paradigm. All the three posterior fixations significantly restricted the motion range of axial rotation loads (P<0.05). However, fixation either with posterior inter-articular screws and plates or inter-laminar clamps also effectively restricted the motion ranges of flexion/extension and lateral bending loads, whereas posterior wiring did not.Conclusion: We described a destabilized canine C1-2complex model. Under a realistic loading paradigm, the model had kinematic analogue of destabilized human C1-2complex. Our results indicated that posterior stabilization using inter-articular fixation techniques or inter-laminar clamps could effectively restrict hypermotility caused by C1-2ligamentous destabilization, and, therefore, appeared to be reliable fixation methods. In contrast, posterior wiring alone would preserve more residual motions, and, thus, might need other adjunctive fixations to offer an optimal condition for solid bony fusion.

C1-C2 posterior fusion in growing patients: long-term follow-up.

A retrospective review of patients undergoing C1-C2 posterior fusion during childhood was undertaken. The aim of this study was to investigate the change in the sagittal curvature of the cervical spine in children after C1-C2 posterior fusion. There have been only a few reports on postoperative changes in the sagittal curvature of the cervical spine after C1-C2 posterior fusion in children. However, they have all described the onset of sagittal postoperative cervical deformities. Between January 1977 and December 1992, a total of 12 children underwent C1-C2 posterior fusion for atlantoaxial instability resulting from congenital malformation in eight, juvenile rheumatoid arthritis in one, and rotatory subluxation in three. The average age at the time of surgery was 10.9 years (range 7-12 years). All children underwent a similar treatment program with gradual preoperative reduction in halo cast, followed by C1-C2 posterior fusion with Mersilene loops in two cases, wiring in eight (Gallie's or Brooks' techniques), and interlaminar clamps in the remaining two. The halo cast made it possible to avoid a hyperextended or hyperflexed C1-C2 position while performing the atlantoaxial fusion, thus ensuring a more anatomic position during C1-C2 fusion. In the postoperative period, the halo cast was maintained for 7 to 9 weeks. RESULTS Follow-up ranged from 7 years to 13 years. Preoperative alignment of the cervical spine was classified into two groups: lordosis (eight patients) and straight (four patients). Postoperative subaxial malalignment (kyphosis) occurred in four cases (33%): these patients showed evidence of spontaneous and gradual sagittal improvement and presented either a straight (two cases) or a lordotic (two cases) cervical spine at follow-up. Immediately after surgery, the cervical spine was normally aligned in the remaining eight patients (lordosis and straight alignment in six and two cases, respectively) and was unchanged at follow-up. At follow-up, none of the 12 patients had a cervical deformity on sagittal plane. In children, a spontaneous realignment of the subaxial kyphosis observed after C1-C2 posterior fusion can be noted at follow-up, when a postoperative deformity occurs (33% in the present series). According to the present findings, it is not always mandatory to perform occipitocervical fusion in children with atlantoaxial instability just to prevent subaxial deformity in the cervical spine.

Atlantal lateral mass screws for posterior spinal reconstruction

A variety of techniques may be used to achieve fixation of the upper cervical spine. Transarticular atlantoaxial screws, posterior interspinous cable and graft constructs, and interlaminar clamps have been used effectively to achieve atlantoaxial fixation. Various anatomical factors, however, may preclude the successful application of these techniques. These factors include aberrant vertebral artery anatomy, irreducible atlantoaxial subluxation, exaggerated cervicothoracic kyphosis, and the absence of the osseous substrate for fixation. In these cases, an alternative method of fixation must be performed. The authors present an alternative method to achieve fixation of the atlas in which lateral mass screws can be applied to atlantoaxial and occipitocervical fixation. Between February 1998 and November 2001, eight patients who ranged in age from 16 to 74 years underwent posterior fixation for upper cervical instability. Diagnoses included C-2 metastastic disease in two patients, irreducible odontoid fractures in two patients, atlantoaxial subluxation in two patients, and transverse ligament synovial cyst in two patients. Various anatomical factors precluded transarticular atlantoaxial screw fixation in seven patients. One patient with a highly unstable spine due to a C-2 metastasis and pathological fracture underwent occipitocervical fusion. Atlantocervical fixation was achieved in seven patients by using varying constructs incorporating C-1 lateral mass screws. Occipitocervical fixation was achieved in one patient by incorporating C-1 lateral mass screws as an additional fixation point. A total of 14 C-1 lateral mass screws were placed in eight patients. There were no intraoperative complications. In all patients rigid fixation was achieved as demonstrated on postoperative radiographs. One patient died on postoperative Day 9 of aspiration pneumonia. At a mean follow-up time of 7.4 months, rigid fixation was maintained in all patients. Atlantal lateral mass screws can be used to provide a safe and efficacious means of achieving atlantoaxial fixation when anatomical constraints preclude the use of a more traditional procedure. Atlantal lateral mass screws may also be incorporated in occipitocervical constructs to provide additional fixation points which may prevent construct failure.

C1-C2 intra-articular screw fixation for atlantoaxial posterior stabilization.

A trial of a new posterior stabilization technique for atlantoaxial instability and a report of preliminary results. To describe a new posterior stabilization technique for atlantoxial instability. Magerl's transarticular screw fixation is an accepted technique for rigid atlantoaxial stabilization, which reportedly has yielded many good clinical results. However, the technique is technically demanding and poses a risk of injury to the nerves and veins. Eleven patients who had been treated with intra-articular screw fixation in combination with Halifax interlaminar clamp (OSTEONICS, Allendale, NJ) for atlantoaxial instability were observed. Results of their clinical examinations and biomechanical studies using resinous bones of a cervical spine model were reviewed. In all patients, occipital pain, neck pain, and neural deficit improved, and bony fusion with no correction loss was shown on radiography. To date, no vascular or neural complications have been found, and no instrumentation failures have occurred. In the biomechanical study, the Halifax with transarticular screw fixation had significantly greater flexion stiffness than the Halifax only or the Halifax with intra-articular screw fixation, but the torsion stiffness of the Halifax with intra-articular screw fixation was significantly greater than that of the other Halifax combinations. The preliminary results showed that this technique was effective in strengthening the rotational stability of the atlantoaxial fixation and was considered useful for atlantoaxial posterior stabilization.

Techniques of posterior subaxial cervical fusion

Techniques of posterior cervical fixation have been augmented and refined over the past century to treat more effectively cervical instability arising from trauma, neoplasia, inflammatory conditions, and degenerative disease. Although adequate for many indications, posterior subluxation stabilization constructs perform best when used primarily to address flexion-type injuries. The integrity of the dorsal tension band is thereby reestablished. Posterior cervical fixation techniques may be subdivided into three general categories: (1) wire or cable constructs (including various interspinous wiring, facet wiring, sublaminar wiring, and wire/polymethylmethacrylate techniques; (2) interlaminar clamps; and (3) articular mass platescrew devices. This article details these techniques and their variations and presents a rationale for choosing a construct.

頚椎脱臼骨折に対するハリファックス椎弓間クランプの使用経験

5 patients requiring posterior fusion for the fracture-dislocation of cervical spine were treated with Halifax interlaminar clamps for internal fixation. 4 patients had unilateral and another patient had bilateral facet dislocation. Fusion was at the C3-4 level in 1 case, the C4-5 level in 3, and the C6-7 level in 1. Facetectomy for reduction at the locked facet was required in 3 cases. Autogenous iliac bone grafting was performed in 1 case with bilateral facet dislocation. Satisfactory stabilization without complication was achieved in all patients. Halifax interlaminar clamps are effective for the posterior stabilization of traumatic lower cervical spinal instability.

Atlantoaxial Arthrodesis Using Halifax Interlaminar Clamps Reinforced by Halo Vest Immobilization: A Long-term Follow-up Experience

THIRTY-TWO PATIENTS WHO underwent atlantoaxial arthrodesis using Halifax interlaminar clamps and halo vests between January 1989 and December 1992 were reviewed. The atlantoaxial instabilities were related to trauma in 16 patients, including 14 patients with unstable odontoid fractures, 1 patient with a complex C2 fracture, and 1 patient with a disrupted transverse ligament. Of the other 16 patients, whose atlantoaxial instabilities were nontraumatic in origin, 9 had instabilities that were secondary to rheumatoid arthritis, 1 had instability that was secondary to tuberculous infection, and 6 had instabilities that were caused by os odontoideum. The patients were followed postoperatively with lateral cervical radiographs for an average of 37 months (range, 16-59 mo). Solid atlantoaxial arthrodeses were achieved in all (100%) of these 32 patients after 32 to 111 days (average, 84.5 d) of halo immobilization, indicating atlantoaxial arthrodeses can be reasonably anticipated when Halifax interlaminar clamps with autogenous iliac bone grafting are reinforced by halo vest immobilization for 3 months.

Atlantoaxial arthrodesis using Halifax interlaminar clamps reinforced by halo vest immobilization: a long-term follow-up experience.

Thirty-two patients who underwent atlantoaxial arthrodesis using Halifax interlaminar clamps and halo vests between January 1989 and December 1992 were reviewed. The atlantoaxial instabilities were related to trauma in 16 patients, including 14 patients with unstable odontoid fractures, 1 patient with a complex C2 fracture, and 1 patient with a disrupted transverse ligament. Of the other 16 patients, whose atlantoaxial instabilities were nontraumatic in origin, 9 had instabilities that were secondary to rheumatoid arthritis, 1 had instability that was secondary to tuberculous infection, and 6 had instabilities that were caused by os odontoideum. The patients were followed postoperatively with lateral cervical radiographs for an average of 37 months (range, 16-59 mo). Solid atlantoaxial arthrodeses were achieved in all (100%) of these 32 patients after 32 to 111 days (average, 84.5 d) of halo immobilization, indicating atlantoaxial arthrodeses can be reasonably anticipated when Halifax interlaminar clamps with autogenous iliac bone grafting are reinforced by halo vest immobilization for 3 months.

Halifax clamps: efficacy and complications in posterior cervical stabilization

BACKGROUND Trauma, neoplasia, rheumatoid arthritis. Down's syndrome, and inflammatory conditions are well-known causes of spinal instability. The Halifax clamp is a method of posterior cervical stabilization that is attached to the adjoining laminae and tightened until no movement between involved vertebrae is possible. Our experience with cases that have utilized Halifax interlaminar clamps, their results and complications are presented. METHODS We conducted a retrospective review of patients with spinal instability in whom Halifax interlaminar clamps were utilized for posterior spinal stabilization. RESULTS Over a 5-year period, 38 patients in our institution underwent posterior stabilization of the cervical spine utilizing the Halifax interlaminar clamp. The patients represent a mix of motor vehicle and sports-related traumas, rheumatoid subluxation, and a single cancer patient. Average follow-up has been 29 months (range 3 to 36 months) Thirty (78.9%) patients have had good results (i.e. stable fusion and regression of symptoms) and no complications. Three patients from our institution, and a fourth patient referred to us postoperatively, developed complications related to the Halifax clamps. Four patients died from unrelated causes. CONCLUSIONS Halifax interlaminar clamps are a safe and effective method for posterior stabilization of various causes of cervical spinal instability.

Stabilization of the cervical spine with the Halifax interlaminar clamp

The Halifax interlaminar clamp is designed for posterior fixation of the cervical column. This technique has the advantages of being fast, safe, light and RM compatible. However the procedure is not useful when the laminae are fractured, not preventing either hyperextension or cervical rotation. We present our experience with the use of this technique in twelve patients who underwent posterior cervical fixation. El clamp interlaminar de Halifax ha sido diseñado para la fijación posterior de lao columna cervical. Esta técnica presenta las ventajas de ser rápida, segura, ligera y resonante-compatible, si bien presenta las desventajas de no poder ser empleados cuando las láminas se encuentran fracturadas, y que no limita la hiperextensión o la rotación cervical. Presentamos nuestra experiencia en el uso de esta técnica en la fijación cervical posterior de doce pacientes.

Halifax interlaminar clamp for posterior cervical fusion: a long-term follow-up review

Fifty consecutive patients requiring posterior cervical fusion for various pathologies were treated with Halifax interlaminar clamps for internal spinal fixation. Fusion involved the C1-2 level in 17 cases, the C1-3 level in one, and the lower cervical area (C2-7) in 32. No patient was lost to follow-up review, which varied from 6 to 40 months (average 21 months). Fusion failed in five patients, three at the C1-2 level, one at the C1-3 level, and one at the C2-3 level. Screw loosening was the cause of failure in four patients, and in one the arch of C-1 fractured. No other complications occurred. Because of the lack of complications, avoidance of the hazards of sublaminar instrumentation, and an excellent fusion rate, this technique is highly recommended for posterior cervical fusion in the lower cervical spine. Atlantoaxial arthrodesis was achieved in only 14 (82%) of 17 patients, however, which might be due to the higher mobility at this multiaxial level. Improved results in this region may be possible by using a new modified interlaminar clamp, by performing adequate bone fusions, and by postoperative external halo immobilization in high-risk patients.

The Halifax Interlaminar Clamp for Posterior Cervical Fusion

A retrospective review of patients who underwent posterior cervical stabilization with Halifax Interlaminar Clamps in four neurosurgical centers in the United Kingdom was performed. Satisfactory bone fusion without complication occurred in all patients in whom lower cervical spinal stabilization (C3-C7) was performed. Complications occurred in 14 of 45 patients undergoing atlantoaxial arthrodesis. In 10 patients, one of the screws loosened, and in 4 patients, one of the clamps disengaged; additional operations to achieve bone fusion were required in 9 patients (20%). The Halifax Interlaminar Clamp is safe and effective for posterior stabilization in the lower cervical spine; there is a significant failure rate associated with its use for atlantoaxial arthrodesis.

Biomechanical Study of C1-C2 Posterior Arthrodesis Techniques

Fifteen cervical spines from cadavers were used to compare the rotational and translational stability of the Brooks fusion, a fusion construct using Halifax interlaminar clamps, and the Gallie fusion. The Brooks and Halifax clamp constructs exhibited significantly greater rotational and translational stiffness than the Gallie construct (P < 0.001). The Halifax clamp construct exhibited greater rotational stiffness and equal translational stiffness when compared with the Brooks construct (P < 0.05). The Brooks and Halifax fixation constructs provided superior fixation but presented technical challenges. The Gallie construct is less technically demanding but provides less stable fixation.

Atlantoaxial arthrodesis using interlaminar clamps. An improved technique.

The atlantoaxial articulation is a multiaxial joint with a freedom of motion that presents unique problems in achieving surgical stability. Several methods of atlantoaxial arthrodesis have been established with varying degrees of immediate and sustained stability and safety. This study describes a new, improved method of posterior atlantoaxial arthrodesis, using (Halifax) interlaminar clamps with interposed bone graft, which provides distinct benefits over existing techniques. This method achieved atlantoaxial union within 12 weeks in 80% of the study's patients (20/25). The clamp fixation was revised in two patients, with subsequent fusion. Three other patients required revision surgery for nonunion due to loosening of the clamp. This was usually caused by incomplete tightening of the screws, with subsequent loosening or dislocation of the device. Possible clamp loosening is a potential problem with the currently available system, and may be a result of the clamp design. Techniques to minimize this risk and suggestions for improvement in the device are discussed. Nonunion is more likely to develop in patients with rheumatoid arthritis. If nonunion occurs, the pseudarthrosis is generally between the posterior bone graft and the ring of C1.

Stabilization of the cervical spine in spondyloepiphyseal dysplasia congenita

Spondyloepiphyseal dysplasia congenita is an inheritable bone dysplasia causing abnormalities that manifest at birth and primarily involve the spine and proximal epiphyses. The clinical findings include short-trunk dwarfism, myopia, frequent retinal detachment, shortening of the spine and proximal extremities, mild thoracic kyphoscoliosis, a barrel-shaped thorax, a short neck, and mild ocular hypertelorism. The characteristic radiographic features are a generalized delay in ossification, flattening and dysplasia of the vertebral bodies, pelvic dysplasia, and retarded ossification of the femoral head and neck. Other radiographic features of interest to the neurosurgeon may be platybasia, kyphoscoliosis, lumbar hyperlordosis, and odontoid hypoplasia. A case of spondyloepiphyseal dysplasia congenita is presented in which an unstable and markedly dysplastic cervical spine was stabilized with Halifax interlaminar clamps and sublaminar wires. The clinical findings and radiographic features are presented and the etiology and neurosurgical management of spondyloepiphyseal dysplasia congenita are discussed.