Object. This study was conducted to determine the indications, safety, efficacy, and complication rate associated with performing corpectomy to achieve anterior decompression of neural elements or for removing anterior lesions. Methods. Between 1987 and 1998, 185 patients underwent cervical corpectomy for the treatment of degenerative spondylitic disease (81 cases), ossification of posterior longitudinal ligament (16 cases), correction of postoperative kyphosis (31 cases), trauma (39 cases), tumor (10 cases), and infection (eight cases). Ninety-nine patients presented with myelopathy, 48 with radiculomyelopathy, 24 with radicular pain, and 14 with neck muscle pain. Eighty-seven patients underwent a one-level corpectomy; 45 of these patients underwent a discectomy at a different level. Seventy patients underwent a two-level corpectomy; 27 of these patients underwent a discectomy at a different level. Twenty-eight patients underwent a three-level corpectomy. Autograft (iliac crest) was used in 141 cases and allograft (fibula) in 44 cases. All but six patients underwent fixation with an anterior plate-screw system. There were no operative deaths. During the procedure the vertebral artery was injured in four patients and preserved in two of them. No neurological sequelae were encountered. Postoperative hoarseness, transient dysphagia, and pain at the graft site were transitory and successfully managed. The fusion rate was 98.8%. Six patients experienced transient deterioration after surgery but they improved. No patient experienced permanent neurological deterioration and 160 (86.5%) improved. Conclusions. Corpectomy has an important role in the management of various degenerative, traumatic, neoplastic, or infectious disorders of cervical spine. Following treatment in this series, radiculopathy always improved and myelopathy was reversed in most patients.

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This paper presents and discusses the results of an ongoing R&D project aiming to design and build a fully automated prototype of a specialized spherical robotic welding system for repairing hydraulic turbine surfaces eroded by cavitation pitting and/or cracks produced by cyclic loading. The system has an embedded vision sensor built to acquire range images by laser scanning over the blade's surface and produce 3D models to locate the damaged spots to be registered in a 3D coordinate system into the robot controller, enabling the robot to repair the flaws automatically by welding in layers. The paper is focused on the robot kinematic model and describes an iterative algorithm to process the inverse kinematics with only five degrees-offreedom. The algorithm makes use of data collected from a vision sensor to ensure that the welding gun axis is perpendicular to the blade's surface. Besides this, it proposes a modelling and optimization mathematical routine for more efficient robot calibration, which can be used with any type of robot. This robot calibration optimization scheme finds the optimal error parameter vector based on the condition number of the manipulator transformation composed from the partial derivatives of the error parameters. Experimental results proved both the iterative algorithm to perform the inverse kinematics and the technique to optimize robot calibration to be very efficient.

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