Improper Length Research Articles

Determining the Optimal Morphometry of Pedicle Screws in Lumbar and Thoracic Spine in the Iranian Population

Background: The improper length and direction of pedicle screw may also cause it to penetrate the adjacent organs. Unknowing the safe zone of dimensions and directions of the pedicles is essential to proper screw placement. Methods: The present study is a cross-sectional morphometric study on patients with spinal trauma referred to the neurosurgical department in 2021. The MARCO PACS software scale measured the CT scan images and included the vertebral left pedicle diameter, pedicle body distance, body aorta distance, pedicle diameter, height, and area. The entry point and direction of the pedicle screw were made with the “free-hand” method. Results: 301 patients were included, consisting of 113 females (37.5%) and 188 males (62.5%). The mean age of the participants was 42.87±12.3 years. “Among all T12 vertebra parameters, just body aorta distance was not significant between genders (p-value=0.311). The pedicle height and body aorta distance were lowest among 18-35 years patients (p-value=0.001) (p-value=0.003), respectively. Post-hoc analysis revealed a significant difference between 18-35 and 51-70 years for body aorta distance in the L1 vertebra (p-value=0.002). Conclusion: The present investigation has shown significant differences between genders for optimal left pedicle screw parameters, which should be considered before surgery.

Design optimization of stent and its dilatation balloon using kriging surrogate model

BackgroundAlthough stents have great success of treating cardiovascular disease, it actually undermined by the in-stent restenosis and their long-term fatigue failure. The geometry of stent affects its service performance and ultimately affects its fatigue life. Besides, improper length of balloon leads to transient mechanical injury to the vessel wall and in-stent restenosis. Conventional optimization method of stent and its dilatation balloon by comparing several designs and choosing the best one as the optimal design cannot find the global optimal design in the design space. In this study, an adaptive optimization method based on Kriging surrogate model was proposed to optimize the structure of stent and the length of stent dilatation balloon so as to prolong stent service life and improve the performance of stent.MethodsA finite element simulation based optimization method combing with Kriging surrogate model is proposed to optimize geometries of stent and length of stent dilatation balloon step by step. Kriging surrogate model coupled with design of experiment method is employed to construct the approximate functional relationship between optimization objectives and design variables. Modified rectangular grid is used to select initial training samples in the design space. Expected improvement function is used to balance the local and global searches to find the global optimal result. Finite element method is adopted to simulate the free expansion of balloon-expandable stent and the expansion of stent in stenotic artery. The well-known Goodman diagram was used for the fatigue life prediction of stent, while dogboning effect was used for stent expansion performance measurement. As the real design cases, diamond-shaped stent and sv-shaped stent were studied to demonstrate how the proposed method can be harnessed to design and refine stent fatigue life and expansion performance computationally.ResultsThe fatigue life and expansion performance of both the diamond-shaped stent and sv-shaped stent are designed and refined, respectively. (a) diamond-shaped stent: The shortest distance from the data points to the failure line in the Goodman diagram was increased by 22.39%, which indicated a safer service performance of the optimal stent. The dogboning effect was almost completely eliminated, which implies more uniform expansion of stent along its length. Simultaneously, radial elastic recoil (RR) at the proximal and distal ends was reduced by 40.98 and 35% respectively and foreshortening (FS) was also decreased by 1.75%. (b) sv-shaped stent: The shortest distance from the data point to the failure line in the Goodman diagram was increased by 15.91%. The dogboning effect was also completely eliminated, RR at the proximal and distal ends was reduced by 82.70 and 97.13%, respectively, and the FS was decreased by 16.81%. Numerical results showed that the fatigue life of both stents was refined and the comprehensive expansion performance of them was improved.ConclusionsThis article presents an adaptive optimization method based on the Kriging surrogate model to optimize the structure of stents and the length of their dilatation balloon to prolong stents fatigue life and decreases the dogboning effect of stents during expansion process. Numerical results show that the adaptive optimization method based on Kriging surrogate model can effectively optimize the design of stents and the dilatation balloon. Further investigations containing more design goals and more effective multidisciplinary design optimization method are warranted.

Change of pectoralis minor length, and acromial distance, during scapular retraction at 60° shoulder elevation

As the pectoralis minor muscle is inserted into the coracoid process, an improper length of this muscle would affect scapular and shoulder motions. Therefore, this study is proposed to assess the effects on pectoralis minor's length and acromial distance after active scapular retraction in scaption at 60° elevation. Sixty right-hand-dominant participants (11 males, 49 females) were randomized into an intervention group and a control group. The intervention group performed pectoralis minor muscle stretching by active scapular retraction, while the control group were asked to sit in an upright position. The result shows that, the mean lengths of pectoralis minor in the intervention group were significantly increased when compared with those of the control group (p=0.004 and p=0.014 respectively). Simultaneously, the reduction in acromial distance of this intervention group was substantially greater than the control group's (p<0.001 and p=0.001 respectively). However, it should be noted that the results reported only relate to the period immediately following muscle stretching.

An Adjustable-Length Intramedullary Nail: Development and Mechanical Evaluation in Cervine Tibiae

Intramedullary nails are the gold standard of fracture fixation, yet problems can still arise due to their manufacture in discrete lengths. Patient outcomes are less favorable when implanted with an improper length nail, and the wide range of discrete length options can increase the size hospital inventory. Prototypes of adjustable-length intramedullary nails were developed and tested in axial compression, torsion, and four-point bending. These prototypes are comparable to conventional nails in axial and bending stiffness. The torsional stiffness of the prototypes is less than that of conventional nails, but may be sufficient for clinical use.

Revision Stapedectomy Surgery

A review of 79 patients undergoing revision stapedectomy by Dr M. E. Glasscock revealed the mean time from primary to revision surgery to be approximately seven years, with hearing loss being the most common symptom. The hearing loss was secondary to inferior displacement of the prosthesis in 30% of cases, and much less commonly was due to incus necrosis, perilymph fistula, residual footplate, oval window reclosure, or improper length of prosthesis. Problems with displacement or improper length of prosthesis caused earlier patient symptomatology and, therefore, earlier revision surgery, all patients having a good prognosis for postoperative hearing except those whose prosthesis was too long. Hearing loss secondary to incus necrosis occurred later, and hearing loss associated with fistula occurred in equal proportions, early as well as late. Vertigo or dysequilibrium was the major complaint with perilymph fistula or an excessively long prosthesis. Patients with either problem predictably had a worse

CIGARETTE SMOKING AND THE PHYSICIAN

Letters and Comments1 October 1968CIGARETTE SMOKING AND THE PHYSICIANDAVID J. CROSBY, M.D.DAVID J. CROSBY, M.D.Search for more papers by this authorAuthor, Article, and Disclosure Informationhttps://doi.org/10.7326/0003-4819-69-4-845_1 SectionsAboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissions ShareFacebookTwitterLinkedInRedditEmail ExcerptTo the Editor: I truly enjoyed the editorial on smoking by Edward J. Huth, M.D. (Ann. Intern. Med. 69: 163, 1968). His attitude toward smoking is deliciously analogous to that of Carry Amelia Nation towards alcohol. I'm only surprised that he has not recommended "hatchetization" of cigarette machines! Incidentally, Carry also spoke against tobacco, foreign foods, corsets, skirts of improper length, and paintings of the sort found in barrooms.Dr. Huth has shown remarkable restraint, but nonetheless I'm afraid that his evangelical attempts to change national patterns of behavior will produce about the same response as that evoked by Carry... This content is PDF only. To continue reading please click on the PDF icon. Author, Article, and Disclosure InformationAffiliations: Department of Internal Medicine Tucson Hospitals Medical Education Program Tucson, Ariz. PreviousarticleNextarticle Advertisement FiguresReferencesRelatedDetails Metrics 1 October 1968Volume 69, Issue 4Page: 845-845KeywordsAlcoholsBehaviorFood Issue Published: 1 October 1968 PDF downloadLoading ...