Assessment of adjacent-segment mobility after cervical disc replacement versus fusion: RCT with 1 year’s results

Disc prostheses have been designed to restore and maintain cervical segmental motion and reduce the accelerated degeneration of the adjacent level. There is no knowledge about the reaction of the neighboured asymptomatic segments after implantation of prostheses or fusion. The effects of these procedures to segmental movement of the uninvolved vertebrae have not been subjected to studies so far. The objective of this study was to compare the segmental motion following cervical disc replacement versus fusion and the correlation to the clinical outcome. Another aim was to compare the segmental motion of the asymptomatic segments above the treated ones and to compare both with Roentgen stereometric analysis (RSA) including the asymptomatic segments. 20 patients with one-level cervical radiculopathy scheduled for surgery were randomized to arthroplasty (10 patients, study group) or anterior cervical discectomy and fusion (10 patients, control group). Clinical results were evaluated using Visual Analogue Scale and Neck Disability Index. RSA was performed immediately postoperative, after 6 and 12 months. The adjacent segment showed a significantly higher segmental motion in all three-dimensional axes in comparison to the segment treated with prostheses (P < 0.05). In the fusion group the segmental motion of the adjacent segment was significantly higher in all three-dimensional axes (P < 0.05) at each examination time. When the adjacent level of both groups is compared, the fusion group could show a higher segmental motion in all three-dimensional axes, but without significant difference (P > 0.05) 1 year after surgery. Regarding the clinical results, there was no significant difference in pain relief between both groups (P > 0.05). In conclusion, the adjacent segment could show a higher segmental motion, when compared with the segment either treated with prostheses or fusion. There was no significant difference in segmental motion adjacent to prosthesis or fusion. Clinical results did also show no significant difference in pain relief between both groups

Disc replacement using Pro-Disc C versus fusion: a prospective randomised and controlled radiographic and clinical study

Anterior cervical discectomy and fusion (ACDF) may be considered to be the gold standard for treatment of symptomatic degenerative disc disease within the cervical spine. However, fusion of the segment may result in progressive degeneration of the adjacent segments. Therefore, dynamic stabilization procedures have been introduced. Among these, artificial disc replacement by disc prosthesis seems to be promising. However, to be so, segmental motion must be preserved. This, again, is very difficult to judge and has not yet been proven. The aim of the current study was to first analyse the segmental motion following artificial disc replacement using a disc prosthesis. A second aim was to compare both segmental motion as well as clinical result to the current gold standard (ACDF). This is a prospective controlled study. Twenty-five patients with cervical disc herniation were enrolled and assigned to either study group (receiving a disc prosthesis) or control group (receiving ACDF, using a cage with bone graft and an anterior plate.) Radiostereometric analysis was used to quantify intervertebral motion immediately as well as 3, 6, 12 and 24 weeks postoperatively. Further, clinical results were judged using visual analogue scale and neuro-examination. Cervical spine segmental motion decreased over time in the presence of disc prosthesis or ACDF. However, the loss of segmental motion is significantly higher in the ACDF group, when looked at 3, 6, 12 and 24 weeks after surgery. We observed significant pain reduction in neck and arm postoperatively, without significant difference between both groups (P > 0.05). Cervical spine disc prosthesis preserves cervical spine segmental motion within the first 6 months after surgery. The clinical results are the same when compared to the early results following ACDF

Optimisation of schedules for the inspection of railway tracks

Inspection of railway tracks involves a high volume of short-duration tasks (e.g. visual inspection, vehicle-based inspection, measurement, etc.) each of which is repeated at different frequencies and time intervals. It is important to gain asmany benefits as possible from the inspection tasks, which incur huge expenses. To date, various optimisation methods have been incorporated into the schedule generation to determine an inspection order for a known number and geographical location of tracks. Due to the specific requirements of certain tracks or inspection problem—for example, the number of schedule parameters and one-off or incremental type schedules—researchers have developed moresophisticated and problem-dependent optimisation methods. However, introduction of a new inspection technology and policy in the last five years, especially in the United Kingdom, has urged a remodelling of the scheduling problem in track inspection in order to cope up with the new operational and business constraints. Thus, this paper conducts a review and gap analysis of previous studies with regard to track inspection scheduling problems from an optimisation point of view. In addition, the authors discuss several potential research interests resulting from the gap analysis undertaken. This studyshows that heuristic methods are popular among researchers in searching for an optimal schedule subject to single or multiple optimisation function(s) while satisfying various technical and business constraints