Atlantal Lateral Mass Screws for Posterior Spinal Reconstruction
Atlantal Lateral Mass Screws for Posterior Spinal Reconstruction
Object. 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.
Methods. 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.
Conclusions. 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.
A variety of techniques exist for fixation of the upper cervical spine. We describe a method for inserting screws into the lateral mass of the atlas to achieve posterior cervical fixation. This technique was recently described by Harms and Melcher as an alternative method to achieve atlantoaxial fixation. In this report we describe our experience using C-1 lateral mass screws to achieve posterior cervical fixation.
Atlantal lateral mass screws may be used to provide additional fixation points in occipitocervical constructs, possibly increasing resistance to construct failure in the cervical spine without increasing the number of cervical levels fused. Additionally, C-1 lateral mass screws may be used as a supplement to or substitute for other forms of atlantoaxial fixation. Techniques for achieving atlantoaxial fusion include posterior interspinous fusion with sublaminar cables and iliac crest bone graft, C1-2 transarticular screw fixation, Although each of these methods has been successfully used to achieve atlantoaxial fusion, anatomical factors may exist in certain cases that preclude their use. Interspinous fusion at C1-2 with sublaminar cables or interlaminar clamps cannot be performed if the posterior elements of C-1 or C-2 are absent or disrupted. Atlantoaxial transarticular screws cannot be placed successfully in the presence of a medially located VA, irreducible subluxation, severe cervicothoracic kyphosis, or destruction of the C-2 pars interarticularis. In these cases constructs incorporating C-1 lateral mass screws may be used to achieve fixation. We present a small case series in which C-1 lateral mass screws were used to achieve atlantoaxial fixation when anatomical characteristics precluded the use of traditional fixation methods. Also included in this series is one case in which C-1 lateral mass screws were used to provide additional fixation points for occipitocervical fusion.
Object. 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.
Methods. 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.
Conclusions. 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.
A variety of techniques exist for fixation of the upper cervical spine. We describe a method for inserting screws into the lateral mass of the atlas to achieve posterior cervical fixation. This technique was recently described by Harms and Melcher as an alternative method to achieve atlantoaxial fixation. In this report we describe our experience using C-1 lateral mass screws to achieve posterior cervical fixation.
Atlantal lateral mass screws may be used to provide additional fixation points in occipitocervical constructs, possibly increasing resistance to construct failure in the cervical spine without increasing the number of cervical levels fused. Additionally, C-1 lateral mass screws may be used as a supplement to or substitute for other forms of atlantoaxial fixation. Techniques for achieving atlantoaxial fusion include posterior interspinous fusion with sublaminar cables and iliac crest bone graft, C1-2 transarticular screw fixation, Although each of these methods has been successfully used to achieve atlantoaxial fusion, anatomical factors may exist in certain cases that preclude their use. Interspinous fusion at C1-2 with sublaminar cables or interlaminar clamps cannot be performed if the posterior elements of C-1 or C-2 are absent or disrupted. Atlantoaxial transarticular screws cannot be placed successfully in the presence of a medially located VA, irreducible subluxation, severe cervicothoracic kyphosis, or destruction of the C-2 pars interarticularis. In these cases constructs incorporating C-1 lateral mass screws may be used to achieve fixation. We present a small case series in which C-1 lateral mass screws were used to achieve atlantoaxial fixation when anatomical characteristics precluded the use of traditional fixation methods. Also included in this series is one case in which C-1 lateral mass screws were used to provide additional fixation points for occipitocervical fusion.
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