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PubMed1989

Fractures of the odontoid process. Treatment with anterior screw fixation.

Seventeen cases of Anderson and D'Alonzo Type II and "shallow" Type III fractures of the odontoid, treated by anterior screw fixation, were reviewed and compared with previously published series of fractures treated nonoperatively, treated with posterior C1-C2 arthrodeses, and with anterior screw fixation series. Although the nonunion rate (12%) and major complication rate (24%) in the present series were higher than those previously reported, the combined rates of all anterior screw fixation series were comparable to those of posterior C1-C2 arthrodesis studies. Three of the complications presented occurred in cases that in retrospect were inappropriate for the use of this technique. These included a verified nonunion and 2 individuals with markedly osteoporotic bone and unfavorable fracture type. Because of the difficulty involved in mastering anterior screw fixation of the dens, its use should be limited to experienced spine surgeons with the appropriate surgical facilities.

Axis, Cervical Vertebra↗
PubMed1990

Histology of the alar and transverse ligaments.

Seven sets of human transverse and alar ligaments, after tensile testing, and eight corresponding ligaments without testing, were examined histologically with respect to their fiber composition and fiber orientation. Various staining techniques were supplemented by polarized light microscopy. Both the transverse and the alar ligaments consist of collagen fibers, with very few elastic fibers in the peripheral layer. In the central portion of the transverse ligament, the collagen fibers cross each other at an angle of approximately 30 degrees. Close to the dens, the transverse ligaments show on their ventral side a transition into fibrocartilage. Except for the immediate site of failure, no differences became evident between tested specimens and controls. The collagen, as the almost exclusive constituent, together with the fiber orientation determine the mechanical properties of these ligaments. This supports the hypothesis that the ligaments could be irreversibly overstretched or even ruptured when the head is rotated and, in addition, flexed by impact trauma, especially in unexpected rear-end collisions.

Aged↗
PubMed1990

Posttraumatic atlanto-axial subluxation and myelopathy. Efficacy of anterior decompression.

Compression of the neuraxis may occur after displaced fractures of the dens. Nonunion or malunion increases the risk of developing neurologic complications because of the resulting atlanto-axial instability. Posterior decompression has generally been the surgical solution to myelopathy at this level. Two patients with cervical myelopathy due to displaced ununited dens fractures were treated with posterior fossa decompression and high cervical laminectomy. Both patients deteriorated after the surgery. Most of their neurologic deficits finally resolved after microsurgical transoral decompression (by resection of the dens). In those patients in whom atlanto-axial instability causes primarily anterior compression of the neuraxis, especially by a bony lesion, decompression posteriorly may not achieve the desired effect, and, instead, may cause a deterioration in the patient's condition. Anterior atlanto-axial subluxation effectively lengthens the bony spinal canal, which results in stretching of the relatively inelastic spinal cord over the bony deformity. If indirect methods of reduction fail to relieve the condition, then anterior transoral decompression is recommended.

Atlanto-Axial Joint↗
PubMed1993

The trabecular anatomy of the axis.

This article describes the internal anatomy of C2. Although some C2 specimens showed a high density of trabecular bone throughout, a feature noted in all specimens was a void or very hypodense area of bone located immediately beneath the dens. The observed nonuniform distribution of trabecular bone within the axis is considered to have an effect on internal fixation of this bone. The good cancellous bone quality consistently observed in the lateral masses and beneath the facets, as well as near the bony end plates, suggests that these areas may be reasonable sites for the insertion of internal fixation devices. The hypodense area observed in the upper portion of C2 would suggest that fixation devices inserted through this area may obtain relatively poor purchase and may be prone to cut-through failure.

Axis, Cervical Vertebra↗
PubMed1993

Atypical hangman's fractures.

Nineteen cases of traumatic spondylolisthesis of the axis, including 13 standard hangman's fractures and 6 anterolistheses of the C2 vertebral body associated with Effendi's atypical hangman's fractures, were studied. Unlike the standard Effendi Type I or Type II fractures, atypical hangman's fractures, occurring through the posterior aspect of the vertebral body with unilateral or bilateral continuity of the posterior cortex or pedicle, routinely narrow the spinal canal because of the fracture pattern and degree of subluxation. These atypical C2 injuries were more frequent and more often accompanied by paralysis (33%) than was previously anticipated. Because of their greater potential for neurologic compromise, it is essential that these fractures be recognized as distinct from standard Types I and II C2 fractures. Larger series should clarify both the true incidence of paralysis and long-term results from these unique C2 injuries.

Adult↗
PubMed1993

Atlantoaxial dislocation as the presenting symptom of ankylosing spondylitis.

A 27-year-old woman presented with nontraumatic atlantoaxial dislocation that required a C1-C2 fusion. A comprehensive investigation initially failed to reveal any evidence of infectious or rheumatologic disease and she remained well for 3 1/2 years, at which time a diagnosis of ankylosing spondylitis was established. There are no other similar cases reported in the medical literature. When dealing with a patient who has experienced a spontaneous atlantoaxial dislocation, a thorough assessment looking for an underlying infectious or inflammatory etiology is mandatory. Furthermore, the authors recommend that any patient who has negative investigations be followed long-term; an underlying covert inflammatory cause may only become evident after significant delay.

Adult↗
PubMed1993

Nonrheumatoid cranial settling.

Cranial settling is a condition in which erosive changes of the atlantal lateral masses result in downward telescoping of the atlas onto the axis body, anterior displacement of the atlantal posterior arch, and subsequent ventral and dorsal cervicomedullary compression. Cranial settling is described in conjunction with rheumatoid basilar invagination and atlanto-axial instability, possibly representing the most life-threatening abnormality associated with rheumatoid arthritis. The authors describe a case of symptomatic cranial settling in a nonrheumatoid patient with chronic, severe, spasmodic torticollis resulting in erosive changes in the occipito-atlanto-axial complex.

Atlanto-Axial Joint↗
PubMed1994

Solitary infantile myofibromatosis of axis. A case report.

Lytic lesions of the cervical spine are rare and may be caused by infection or tumors. The authors report a rare case of solitary infantile myofibromatosis presenting as a lytic lesion of the second cervical vertebral body (C2) and odontoid, causing atlanto-axial instability.

Adolescent↗
PubMed1994

Posterior atlantoaxial fusion. A new internal fixation device.

STUDY DESIGN: Biomechanical and clinical testing of an atlantoaxial posterior fixation device. OBJECTIVES: The authors tested an internal fixation device to maintain the atlas and axis in an anatomic relationship while fusion occurs. The device should also facilitate intraoperative reduction of any residual anterior atlantoaxial subluxation. The device should allow the use of cancellous rather than cortical bone graft. SUMMARY OF BACKGROUND DATA: Previous techniques of atlantoaxial fusion were not universally successful, and the quality of reduction was assessed infrequently. METHODS: Biomechanical testing of the fixator and clinical use in two "problem" patients requiring atlantoaxial fusion. RESULTS: Biomechanical testing indicated the device should be successful. Clinical testing was successful. CONCLUSION: The new fixator facilitates posterior atlantoaxial fusion in an anatomical position.

Atlanto-Axial Joint↗
PubMed1995

Natural course of cervical spine lesions in rheumatoid arthritis.

STUDY DESIGN: This study analyzed the natural course of cervical spine involvement in rheumatoid arthritis by serial radiographs. OBJECTIVES: The purpose was to determine the pattern of progression of cervical spine lesions in rheumatoid arthritis and predictors for the extent of progression. SUMMARY OF BACKGROUND DATA: Subluxation frequently occurs as a result of rheumatoid involvement of the cervical spine. It may be severe in patients with mutilans deformities in the hands and feet. The extent of progression in a given patient is still unpredictable. METHODS: Serial cervical radiographs in 49 patients with rheumatoid arthritis were analyzed. The extent of progression was evaluated by rheumatoid arthritis subset defined previously, which reflected the final extent of joint erosion in this systemic disease and could be roughly classified during early stages of the disease. RESULTS: In the upper cervical spine, reducible anterior atlantoaxial subluxation occurred first. Vertical subluxation of the axis appeared next. Irreducible change of preceding anterior atlantoaxial subluxation was a sign of the start of vertical subluxation. In subaxial lesion, subluxation occurred less frequently (22.4%) than upper cervical lesion (77.6%). The extent of progression was different with the rheumatoid arthritis subset. In the upper cervical spine, none of the subset with least erosive disease developed vertical subluxation, whereas 52% of the subset with more erosive disease and 88% of the subset with mutilating disease advanced to vertical subluxation. The extent of progression was well correlated with the number of joints with erosion. Subaxial subluxation was often seen and became irreducible in mutilating disease and more erosive disease, but not in least erosive disease. CONCLUSIONS: A progressive pattern of the upper cervical subluxations was clarified. That is, upper cervical lesions progressed from reducible anterior atlantoaxial subluxation to irreducible anterior atlantoaxial subluxation with vertical subluxation. This extent of progression was different with the rheumatoid arthritis subset, which was also related to the development of subaxial subluxation. The most aggressive arthritis classification, a subset with mutilating disease, had the more severe subluxation in both upper and subaxial cervical spine.

Adolescent↗
PubMed1995

Cervical myelopathy caused by pseudoarthrosis between the atlas and axis associated with diffuse idiopathic skeletal hyperostosis.

STUDY DESIGN: This is a report of a patient with severe cervical myelopathy due to pseudoarthrosis between the posterior tubercle of the atlas and the spinous process of the axis, associated with diffuse idiopathic skeletal hyperostosis. Radiographs of 170 patients with neck pain were reviewed to identify lesions involving abnormal contact between the atlas and axis. OBJECTIVE: Based on an analysis of 170 radiographs, the prevalence of the reported condition was estimated. SUMMARY OF BACKGROUND DATA: A number of histologic studies on pseudoarthrosis involving the lumbar spine have been reported. In contrast, lesions between the posterior tubercle of the atlas and the spinous process of the axis have not been reported in association with cervical myelopathy. METHODS: Clinical and pathologic features of a patient with pseudoarthrosis between the posterior tubercle of the atlas and the spinous process of the axis were investigated. Radiographs of 170 Japanese patients over 40 years old were examined, and abnormal contact between the atlas and axis was classified into two groups based on the degree of spinal hyperostosis. RESULTS: Of 170 patients, 53 showed abnormal contact between the atlas and axis. The prevalence of abnormalities in the pronounced hyperostosis group (Forestier's stages II and III) was much higher than in the group with normal or slight hyperostosis. Two men had radiographic patterns showing osteophytes projecting into the spinal canal and associated with marked cervical myelopathy. CONCLUSION: In the group with pronounced hyperostosis, pseudoarthrosis or a variant can cause serious problems in the upper cervical spine that should not be overlooked.

Age Distribution↗
PubMed1996

Anterior extraoral surgery to the upper cervical spine.

STUDY DESIGN: A series of 10 patients surgically treated with prevascular or retrovascular extraoral retropharyngeal approach to the upper cervical spine is examined. OBJECTIVES: In orthopedic surgery, retropharyngeal approach may replace the transoral surgery, obviating the risks of infection and the uncomfortable postoperative course of cases in which median labiomandibular glossotomy was used to accomplish complex bone reconstruction. SUMMARY OF THE BACKGROUND DATA: The transoral approach is reported in literature as the classical anterior access to the upper cervical spine that provides direct exposure for anterior decompression of the spinal cord. The risks, the surgical limits, and the postoperative difficulties of transmucosal access suggest the use of an anterior extraoral retropharyngeal approach in orthopedic surgery. METHODS: The series includes four neoplastic lesions (osteoma, aneurismal bone cyst, giant cell tumor, solitary metastasis), three retropharyngeal ossifications resulting from diffuse idiopathic skeletal hyperostosis, and a single case of os odontoideum, craniocervical malformation, and postlaminectomy kyphosis. RESULTS: At follow-up evaluation, all patients achieved a satisfactory outcome, with good clinical and radiographic results; nasotracheal intubation obviated the need for tracheostomy. The wide surgical exposure allowed reconstruction with iliac strut bone grafts and internal fixation in six patients, avoiding the need of a halo device. The only complications were four instances of transient palsies of the marginal mandibular branch of the facial nerve. CONCLUSIONS: In the anterior surgery of the upper cervical spine, the prevascular approach allows a wide surgical exposure, with visualization similar to that obtained with median labiomandibular glossotomy. The retrovascular approach is indicated in selected cases, such as tumor adjacent to the vertebral artery and C1-C2 arthrodesis with bilateral transarticular screws according to Barbour.

Adolescent↗