by G. H. | Jul 31, 2017 | News, Wirbelsäule, Wirbelsäule chir.
Preclinical evaluation of posterior spinal fixators: a comparative analysis
La Barbera L, Villa T, Galbusera F, Wilke HJ
Objective: Preclinical evaluation of spinal implants is a mandatory step to ensure their reliability and safety before clinical use and implantation. The American Society of Testing and Materials reapproved a standard for the evaluation and comparison of mechanical properties of posterior spinal fixators [F1717-2013], which reproduces a vertebrectomy model and assumes that the anterior column is totally compromised from supporting the load (Figure a). In this frame-work polyethylene blocks are used to mimic vertebral bodies (Figure b). Even if the overall test set-up (distances and angles) should be representative of the specific clinical use of the implant in a worst-case condition, some parameters are unclear and a direct comparison with anatomical/biomechanical data, when available, is difficult. This investigation aims at investigating whether the experimental set-up correctly describe the physiological anatomy of a stabilized segment and how each parameter affects the stress arising in the device.
Method: Anatomical parameters depending on the spinal level, were compared to available literature data or directly measured on biplanar X-ray images of 14 patients.
Others mechanical variables describing the design of the implant were considered and all parameters were investigated by means of a comparative numerical analysis. Stress values were calculated either considering the combination of the average values for each parameter and their worst case combination depending on the spinal level.
Results and conclusion: The experimental configuration represents quite well the anatomy of an average thoracolumbar segment. The stress on the spinal fixator is significantly influenced by the lever arm of the applied load, the position of the center of rotation of the functional spine unit and the pedicular inclination with respect to the sagittal plane. The worst case combination of anatomical parameters demonstrates that a posterior spinal fixator implanted below T5 could potentially undergo higher stresses than according to standard configuration, with a maximum increase of 15.2% at L1 level. Considering a polyaxial screw having its head tilted cranially, this value raises to 22.2%.
A revision of F1717 standard is suggested in order to take into account for the worst case condition found at L1 level: this will guarantee a higher reliability and safety of posterior fixator for a wider population of patients.
Deutscher Kongress für Orthopädie und Unfallchirurgie (DKOU 2014). Berlin, 28.-31.10.2014. Düsseldorf: German Medical Science GMS Publishing House; 2014. DocWI41-1066
doi: 10.3205/14dkou273, urn:nbn:de:0183-14dkou2731
Published: October 13, 2014
© 2014 La Barbera et al.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by-nc-nd/3.0/deed.en). You are free: to Share – to copy, distribute and transmit the work, provided the original author and source are credited.
by G. H. | Jun 25, 2017 | News, Wirbelsäule chir.
Prevalence of Degenerative Changes of the Atlanto-Axial Joints
Betsch M, Blizzard S, Boshears E, Gernhart T, Yoo J
Obbjective: Degeneration of the atlanto-dens and atlanto-axial joints is associated with cervical spine pain and may also be associated with an increased risk of dens fracture. However, there is paucity of literature describing the prevalence of specific degenerative changes in the atlanto-dens and atlanto-axial facet joints.
Method: We conducted a retrospective study of 1,543 adult trauma patients who received a cervical spine computed tomography scan. The anterior atlanto-dens joint interval was measured. The presence or absence of intraosseous cysts and synovitis was recorded. Degeneration of the atlanto-dens and atlanto-axial facet joints at age intervals was quantified.
Results: The atlanto-dens interval narrowed linearly with age (R2=0.992; p<0.001). The prevalence of intraosseous cysts increased exponentially from 4.2% to 37.4%, and synovitis increased from 0% to 11.1%. Intraosseous cyst formation generally began in the 2nd to 3rd decade of life and synovitis in the 5th and 6th decade of life. Facet joints also demonstrated age related changes; however, the rate of degenerative changes was lower than in the atlanto-dens joint.
Conclusion: To our knowledge, this is the first study that documents specific changes of both atlanto-dens and atlanto-axial facet joints as a function of age in a large cohort of 1,543 patients. These changes increased exponentially with age, and may contribute to pain and limitation in motion. In light of our findings and recent studies demonstrating the association between degeneration and dens fracture in elderly, cervical spine radiographs of elderly patients should be carefully assessed for these changes.
Deutscher Kongress für Orthopädie und Unfallchirurgie (DKOU 2014). Berlin, 28.-31.10.2014. Düsseldorf: German Medical Science GMS Publishing House; 2014. DocWI40-977
doi: 10.3205/14dkou258, urn:nbn:de:0183-14dkou2585
Published: October 13, 2014
© 2014 Betsch et al.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by-nc-nd/3.0/deed.en). You are free: to Share – to copy, distribute and transmit the work, provided the original author and source are credited.
by G. H. | Jun 12, 2017 | Fuß, News
Sport Activity after AMIC-aided Repair of Osteochondral Lesions of the Talus
Wiewiorski M, Barg A, Valderrabano V
Objective: Data regarding sport activity after autologous matrix-induced chondrogenesis (AMIC)-aided repair of osteochondral transplantation of the talus is limited. The aim of this study was to determine whether AMIC-aided osteochondral repair of the talus is a clinically successful treatment and enables patients to pursue regular and ongoing recreational sporting activities.
Method: Sixty patients were retrospectively analyzed to determine their sporting and recreational activities at an average of 30.7 months postoperatively (range, 12-70 months). The clinical evaluation included the visual analog scale (VAS) for pain, the Tegner activity scale, and the Activity Rating Scale (ARS).
Results ans conclusion: The VAS illustrated significant preoperative to postoperative improvements (6.8 to 3; P<.01). The Tegner score dropped from 3.2 preoperatively to 3.1 after surgery (P=.87), and the ARS decreased from 2.77 preoperatively to 1.60 postoperatively (P=.16). Regarding sporting activity, 95.3% of the patients were engaged in sports during their lifetimes compared with 51.2% the year before surgery and 55.8% at the time of survey. The duration of sports activities did not significantly change after surgery (P=.87). Of the 43 patients, 33% were very satisfied with the procedure, 51% were satisfied, and 16% were not satisfied.
Patients engage in fewer, less frequent sporting activities when a symptomatic osteochondral lesion (OCL) at the talus is present. AMIC-aided repair shows good clinical midterm results and allows patients to return to sporting activity. However, we found patients modify their postoperative sporting activities, and we noted a reduction of participation in high-impact and contact sports.
Deutscher Kongress für Orthopädie und Unfallchirurgie (DKOU 2014). Berlin, 28.-31.10.2014. Düsseldorf: German Medical Science GMS Publishing House; 2014. DocWI39-1481
doi: 10.3205/14dkou253, urn:nbn:de:0183-14dkou2531
Published: October 13, 2014
© 2014 Wiewiorski et al.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by-nc-nd/3.0/deed.en). You are free: to Share – to copy, distribute and transmit the work, provided the original author and source are credited.
