RESUMO
OBJECTIVE Posterior atlantoaxial stabilization and fusion using C-1 lateral mass screw fixation has become commonly used in the treatment of instability and for reconstructive indications since its introduction by Goel and Laheri in 1994 and modification by Harms in 2001. Placement of such lateral mass screws can be challenging because of the proximity to the spinal cord, vertebral artery, an extensive venous plexus, and the C-2 nerve root, which overlies the designated starting point on the posterior center of the lateral mass. An alternative posterior access point starting on the posterior arch of C-1 could provide a C-2 nerve root-sparing starting point for screw placement, with the potential benefit of greater directional control and simpler trajectory. The authors present a cadaveric study comparing an alternative strategy (i.e., a C-1 screw with a posterior arch starting point) to the conventional strategy (i.e., using the lower lateral mass entry site), specifically assessing the safety of screw placement to preserve the C-2 nerve root. METHODS Five US-trained spine fellows instrumented 17 fresh human cadaveric heads using the Goel/Harms C-1 lateral mass (GHLM) technique on the left and the posterior arch lateral mass (PALM) technique on the right, under fluoroscopic guidance. After screw placement, a CT scan was obtained on each specimen to assess for radiographic screw placement accuracy. Four faculty spine surgeons, blinded to the surgeon who instrumented the cadaver, independently graded the quality of screw placement using a modified Upendra classification. RESULTS Of the 17 specimens, the C-2 nerve root was anatomically impinged in 13 (76.5%) of the specimens. The GHLM technique was graded Type 1 or 2, which is considered "acceptable," in 12 specimens (70.6%), and graded Type 3 or 4 ("unacceptable") in 5 specimens (29.4%). In contrast, the PALM technique had 17 (100%) of 17 graded Type 1 or 2 (p = 0.015). There were no vertebral artery injuries found in either technique. All screw violations occurred in the medial direction. CONCLUSIONS The PALM technique showed statistically fewer medial penetrations than the GHLM technique in this study. The reason for this is not clear, but may stem from a more angulated "up-and-in" screw direction necessary with a lower starting point.
Assuntos
Parafusos Ósseos , Vértebras Cervicais/cirurgia , Fusão Vertebral/métodos , Idoso , Articulação Atlantoaxial/diagnóstico por imagem , Articulação Atlantoaxial/cirurgia , Cadáver , Vértebras Cervicais/diagnóstico por imagem , Feminino , Humanos , Masculino , Complicações Pós-Operatórias/prevenção & controle , Fusão Vertebral/efeitos adversos , Fusão Vertebral/instrumentação , Raízes Nervosas Espinhais/diagnóstico por imagem , Raízes Nervosas Espinhais/lesões , Tomografia Computadorizada por Raios XRESUMO
INTRODUCTION: Spinal cord tumors (SCT) are relatively uncommon and usually require surgical treatment. Readmission within 30days after discharge is an important indicator of health care quality. The aim of this study was to investigate the rates and causes of unplanned readmissions and reoperations after SCT surgery. METHODS: A retrospective analysis of patients' charts at a single center from May 2007 to September 2015 was completed. INCLUSION CRITERIA: history of laminectomy with excision of neoplasm in the spinal cord. EXCLUSION CRITERIA: (1) surgery outside the timeframe; (2) less than 19years old; (3) non-neoplastic intramural pathologies; (4) previous resection at the same location; (5) metastatic lesions. RESULTS: We found 131 patients that met criteria. Six patients (4.5%) were readmitted within 30days and two within 90days (1.5%). Four underwent reoperation: one for a cerebrospinal fluid leak, two for pseudomenigoceles, and one for repeat laminectomy. Resection of intramedullary tumors resulted in twice the risk of having one or more complications compared to extramedullary tumors (RR 2.0; 95% CI: 1.0-4.2; p=0.057), and nearly four times the risk of having a neurological complication (RR 3.8; 95% CI 1.5-9.5; p=0.005). CONCLUSION: This study analyzes readmission, reoperation and complication rates for the surgical care of SCT highlighting how SCT surgery is still involved with morbidity in experienced and specialized centers. This information is useful both for health care enhancement projects and for evidence-based patient counseling.