Design limitations of Bryan disc arthroplasty.

BACKGROUND CONTEXT: Disc arthroplasty is gaining momentum as a surgical procedure in the treatment of spinal degenerative disease. Results must be carefully scrutinized to recognize benefits as well as limitations. PURPOSE: The aim of this study was to investigate factors associated with segmental kyphosis after Bryan disc replacement. STUDY DESIGN/SETTING: Prospective study of a consecutively enrolled cohort of 10 patients treated in a single center using the Bryan cervical disc prosthesis for single-level segmental reconstruction in the surgical treatment of cervical radiculopathy and/or myelopathy. Radiographic and quality of life outcome measures. METHODS: Static and dynamic lateral radiographs were digitally analyzed in patients undergoing Bryan disc arthroplasty throughout a minimum 3-month follow-up period. Observations were compared with preoperative studies looking for predictive factors of postoperative spinal alignment. RESULTS: Postoperative end plate angles through the Bryan disc in the neutral position were kyphotic in 9 of 10 patients. Compared with preoperative end plate angulation there was a mean change of -7 degrees (towards kyphosis) in postoperative end plate alignment (p=.007, 95% confidence interval [CI] -6 degrees to -13 degrees). This correlated significantly with postoperative reduction in posterior vertebral body height of the caudal segment (p=.011, r2=.575) and postoperative functional spine unit (FSU) kyphosis (p=.032, r2=.46). Despite intraoperative distraction, postoperative FSU height was significantly reduced, on average by 1.7 mm (p=.040, 95% CI 0.5-2.8 mm). CONCLUSIONS: Asymmetrical end plate preparation occurs because of suboptimal coordinates to which the milling jig is referenced. Although segmental motion is preserved, Bryan disc arthroplasty demonstrates a propensity towards kyphotic orientation through the prosthesis likely as a result of intraoperative lordotic distraction. FSU angulation tends towards kyphosis and FSU height is decreased in the postoperative state from lack of anterior column support. Limitations of Bryan cervical disc arthroplasty should be carefully considered when reconstruction or maintenance of cervical lordosis is desirable.

Minimally invasive anterior approach to upper cervical spine: surgical technique.

OBJECTIVE: The transoral approach of Spetzler is the classic anterior access to the upper cervical spine that provides direct exposure for anterior decompression of the spinal cord. The risks of infection, the limits in extension, and the postoperative recovery difficulties of transmucosal access suggest the use of an alternative anterior extraoral approach in upper cervical surgery. However, this approach results in complications from nerve palsy because of excessive retraction of the hypoglossal and the superior laryngeal nerves. The goal of this work was to provide anatomic data for an anterior retropharyngeal upper cervical approach through a minimally invasive window below the hypoglossal and the superior laryngeal nerves. METHODS: In two adult cadaveric cervical spines, the anterior approach using the Metrx tubular retractor system through a window between the hypoglossal nerve and the superior laryngeal nerve, as well as below these two nerves, is compared in the exposure of C1 and C2 anteriorly with the aid of an operating microscope. RESULTS: A maximum diameter of the internervous window for the tubular retractor is reached beyond which the superior laryngeal nerve will be excessively stretched. Conversely, the tubular retractor can retract the superior laryngeal nerve superiorly without undue tension. Better proximal exposure is also made possible by angling an end-beveled tubular retractor on the mandible without undue compression on the hypoglossal and superior laryngeal nerves, the marginal mandibular branch of the facial nerve, and the submandibular gland. CONCLUSION: This minimally invasive approach can replace transoral surgery, allowing direct anterior access to C1 and C2 while allowing extension to the lower cervical spine.

Posterolateral dislocation of the C1-C2 articulation associated with fracture of the anterior arch of C1: a case report.

STUDY DESIGN: Case report. OBJECTIVE: To report a rare traumatic C1-C2 dislocation associated with fracture of the anterior arch of the atlas in a neurologically intact patient. SUMMARY OF BACKGROUND DATA: Isolated fractures of the anterior arch of C1 are very rare. There have been reports of horizontal fractures of the anterior arch thought to occur secondary to hyperextension injuries with subsequent avulsion of the anterior tubercle of the atlas. To our knowledge, however, there are no previously reported cases of isolated anterior arch fractures of C1 associated with posterolateral dislocation of the C1-C2 articulation. METHODS: A 53-year-old patient who presented with a posterolateral dislocation of the C1-C2 articulation and an associated anterior arch fracture of C1 is reported. Details of the initial presentation, diagnostic strategy, and initial and definitive management are provided. RESULTS: Closed reduction with halo ring application and gentle manipulation was followed with definitive internal fixation consisting of Magerl C1-C2 transarticular screw fixation coupled with modified Brooks fusion. CONCLUSIONS: Posterolateral C1-C2 dislocation associated with atlantal anterior arch fracture is a rare injury that can be effectively treated with gentle closed reduction under fluoroscopic guidance followed by internal fixation with or without halo vest immobilization. Recognition of associated conditions including vertebral artery compromise, concomitant cervical spine fractures, and life-threatening injuries is paramount to the successful treatment of these patients.

Suspended laminoplasty for wide posterior cervical decompression and intradural access: results, advantages, and complications.

OBJECT: Cervical laminoplasty is a recognized technique commonly used for multilevel posterior cervical decompression, and it is favored over laminectomy for maintaining spinal stability. Traditional hinge techniques, however, limit lateral exposure on one side and can limit dural exposure. The authors present their experience with a modified laminoplasty technique incorporating complete laminectomy and placement of titanium miniplate instrumentation. This method allows wide bilateral posterior decompression and unobscured dural access. METHODS: Twenty-eight patients (mean age 57 years) underwent cervical laminoplasty during a 4-year period. Twenty-seven patients presented with progressive cervical myelopathy. Seventeen patients (61%) had degenerative spondylotic stenosis; nine (32%) underwent resection of an intradural neoplasm. A mean of 3.5 levels were exposed and reconstructed. The follow-up period ranged from 4 months to 4 years (mean 15 months). The mean angular extension-flexion displacement measured between C-1 and C-7 was unchanged postoperatively, with preserved mobility across laminoplasty-treated segments in all patients. The anteroposterior diameter of the spinal canal increased 3.6 mm (27.2%) postoperatively (p = 0.004). In one patient an asymptomatic postoperative kyphosis developed. There were five cases of postoperative infection. One superficial infection resolved after intravenous antibiotic therapy alone, and four deep infections required surgical reexploration. CONCLUSIONS: The advantages of this technique over other laminoplasty methods include wide lateral spinal canal and intradural access, as well as preserved motion with partial restoration of the posterior tension band.