• BIOMECHANICAL STABILITY OF A MOVABLE ARTIFICIAL CERVICAL JOINT

    INTRODUCTION: Anterior cervical discectomy with or without fusion is an acceptable surgical method for the treatment of cervical spondylosis or other spinal disc diseases. A spinal device may be used to immobilize the operated/injured region to promote bony fusion. Clinical studies have shown that motion at spinal segments adjacent to a fused region increases over time and may cause adjacent segment problems. An alternative approach to fusion surgery of the cervical spine is to restore the motion to the diseased joint using an implanted movable artificial joint. The biomechanical stability of the harvested and instrumented cervical spine was determined for physiologic flexion/extension and lateral bending loading mechanics. The instrumented spine consisted of a single level discectomy with subsequent disc replacement using a prototype movable intervertebral implant by Sofamor Danek Group, Memphis, TN.
  • A COMPARISON OF THE CLINICAL BEHAVIOR AND THE HISTOPATHOLOGY OF PLATE VERSUS CAGE-PLATE SYSTEMS FOR CERVICAL FUSION: AN IN VIVO STUDY

    INTRODUCTION: A recent advance in the technology for cervical fusions is the “The Telescopic Anterior Plate Spacer (TAPS)” (Interpore Cross, Inc.). This device is a combination of the anterior plate system and the fusion cage, and has several of the advantages of both. Further, failure modes such as piston effect and subsidence of the construct are believed to be minimized with the new device. The goal of this study was to compare the clinical performance of this device with a more commonly used and well-accepted device, “The CODMAN® Anterior Cervical Plate System” (Johnson and Johnson, Medical Inc.).
  • THREE AND FOUR LEVEL ANTERIOR CERVICAL DISKECTOMY AND FUSION WITH PLATE FIXATION: A PROSPECTIVE STUDY

    PURPOSE: The success of arthrodesis for anterior cervical fusion depends on several factors, including the number of surgical levels. The arthrodesis rate and outcome for patients having specifically three or four level diskectomy and fusion procedures is disappointing [1]. Internal fixation putatively improves these parameters. We prospectively studied fifteen patients who underwent modified Smith-Robinson anterior cervical diskectomy and fusion at three or four operative levels to determine the effect that unicortical anterior plate fixation has on the results. METHODS: Fifteen patients (7 female, 5 male), with an average age of 51 years (range 35 to 77), were followed for an average of 40 months (range 25 to 73). All had an anterior diskectomy, burring of the endplates, placement of an autogenous tricortical iliac crest graft at three (12 patients) or four (3 female patients) levels, and application of a Synthes Cervical Spine Locking Plate.
  • BIOMECHANICAL RATIONALE FOR THE PATHOLOGY OF RHEUMATOID ARTHRITIS IN THE CRANIOVERTEBRAL JUNCTION

    INTRODUCTION: Rheumatoid arthritis (RA) involvement of the occipito-atlanto-axial (C0-C1-C2) complex is commonly seen, however the biomechanical role during disease progression is not well understood. Investigation of progressive disease states does not lend itself to traditional in vitro methods such as cadaver experimentation. Thus, the authors implemented the finite element (FE) method to study the biomechanical factors, if any, that contribute to the development and advancement of RA and its associated clinically-observed lesions.
  • SPINAL CORD SIZE AND SHAPE FOLLOWING CERVICAL LAMINOPLASTY

    PURPOSE: To determine the effect of cervical laminoplasty on the cross-sectional morphology of the spinal cord. METHODS: Cervical laminoplasty with neolamina reconstruction was performed in 40 patients with cervical spondylotic myelopathy from 1992 to 1995. The average age at the time of surgery was 61 years. The average follow-up was 36 months. Spinal cord cross-sectional area and sagittal and coronal cord sizes were measured using an image analysis program pre-operatively, three months and one year postoperatively on axial MRI scans. Interobserver variability was assessed. The data were analyzed using nonparametric statistical tests.
  • CERVICAL CORD NEURAPRAXIA: CLASSIFICATION, PATHOMECHANICS, MORBIDITY, AND MANAGEMENT GUIDELINES

    INTRODUCTION: One hundred ten cases of the transient neurological phenomenon, cervical cord neurapraxia (CCN), are presented. METHOD: The authors established a classification system for CCN, developed a new computerized measurement technique for magnetic resonance (MR) imaging, investigated the relationship of the cervical cord to the canal, and analyzed clinical, x-ray, and MR data. One hundred nine males and one female were included in the study; the average age of the participants was 21 years (range 13-33 years). All episodes occurred during sports participation; 87% occurred while the patient was playing football. Follow-up review lasting an average of 3.3 years was available for 105 patients (95%).
  • CHARACTERISTICS OF UNICORTICAL AND BICORTICAL LATERAL MASS SCREWS IN THE CERIVICAL SPINE

    INTRODUCTION: Lateral mass plating for posterior cervical spine fusion is an effective method for the treatment of traumatic and degenerative instability. The stability of the cervical spine plating system is dependent on a number of factors. One of these factors is the strength that the screw has in terms of bony purchase. The initial description of the technique utilized bicortical screw purchase. The challenge to the surgeon is balancing what is safe versus what is biomechanically sound. The added benefit of bicortical purchase must be weighted against the increased risk of injury to nerve roots and the vertebral artery. The purpose of this study was to analyze the safety, pullout strength and radiographic characteristics of unicortical and bicortical screws within cadaveric specimens and to evaluate the influence of level of training on the positioning of these screws.
  • A META-ANALYSIS OF AUTOGRAFT VERSUS ALLOGRAFT IN ANTERIOR CERVICAL FUSION

    INTRODUCTION. Robinson Smith anterior cervical fusion (ACF) is a common procedure for cervical radiculopathy. Published studies comparing autograft and allograft have not conclusively demonstrated the superiority of either choice of graft. A meta-analysis of published, peer-reviewed journal articles was performed to determine if there is a difference in fusion rate, graft complications, or clinical outcome in patients undergoing anterior cervical fusion using autograft or a log raft. METHODS. A thorough search of the medical literature from 1955 was made using the National Library of Medicine online service, as well as manual searches through the orthopaedic and neurosurgery literature.