Coupled bending-torsion vibration of a homogeneous beam with a single delamination subjected to axial loads and static end moments

Delaminations in structures may significantly reduce the stiffness and strength of the structures and may affect their vibration characteristics. As structural components, beams have been used for various purposes, in many of which beams are often subjected to axial loads and static end moments. In the present study, an analytical solution is developed to study the coupled bending-torsion vibration of a homogeneous beam with a single delamination subjected to axial loads and static end moments. Euler-Bernoulli beam theory and the ＂free mode＂ assumption in delamination vibration are adopted. This is the first study of the influences of static end moments upon the effects of delaminations on natural frequencies, critical buckling loads and critical moments for lateral instability. The results show that the effects of delamination on reducing natural frequencies, critical buckling load and critical moment for lateral instability are aggravated by the presence of static end moment. In turn, the effects of static end moments on vibration and instability characteristics are affected by the presence of delamination. The analytical results of this study can serve as a benchmark for finite element method and other numerical solutions.

Mid-term outcome of arthroscopic TightRope fixation of displaced lateral end clavicular fractures:Average follow-up of 6.1 years

Purpose:Various surgical modalities are available to treat Neer types 2 and 5 unstable fractures of lateral end clavicle but none of them are standardized.Arthroscopic fixation of the displaced lateral end clavicle fractures provides good short-term results but mid- to long-term outcomes are not available.The purpose of this study was to show the mid- to long-term radiological and functional outcomes of these fractures treated arthroscopically by a TightRope device,and to show the complications associated with this procedure.Methods:A retrospective study was conducted over 2 years from January 2014 to December 2015 with a minimum 5-year follow-up.Active patients aged 18–50 years with acute (less than 3 weeks) displaced fracture of lateral end of the clavicle,with a minimum 5-year follow-up were included in the study.Patients with associated fractures of the proximal humerus,glenoid,scapula and acromioclavicular joint injuries were excluded from the study along with open fractures and neurovascular injuries.The outcomes were assessed by objective (complications and radiographic examination) and subjective criteria (quick disabilities of the arm,shoulder and hand score,the Constant-Murley score and the visual pain analogue scale).The data were analyzed by SPSS version 21.0.Results:Totally,42 patients were operated during the study period and 37 were available with a minimum 5-year follow-up.Thirty were male and 7 were female with a mean age of 29.5 years and a mean follow-up of 6.1 years.The mean quick disabilities of the arm,shoulder and hand score was 68.2 ± 4.6 preoperatively and 1.27 ± 2.32 at final follow-up (p < 0.001);the mean visual pain analogue scale score was 6.85 ± 2.2 preoperatively and 0.86 ± 1.60 at final follow-up (p < 0.001).The average Constant-Murley score was 93.38 ± 3.25 at the end of the follow-up.There were 2 fixation failures,with established non-union and 3 patients developed radiographic acromioclavicular joint arthritis.Conclusions:Arthroscopic TightRope fixation of displaced lateral end clavicular fractures provides good radiological and functional outcomes at mid- to long-term follow-up.With the low complication rates and high patient satisfaction,this technique can be considered as a primary option in the surgical treatment of these fractures.

Outcome of distal end clavicle fractures treated with locking plates

Purpose： Fractures of the lateral end of the clavicle are relatively uncommon. These fractures are unstable due to the various deforming forces which act on the fragments as well as the small distal fracture fragment. At most times the deforming forces are not taken into consideration, and the fracture is not fixed securely. In this study, we assessed a fixation technique using the precontoured locking plates to find out whether it provided a stable fixation with good functional outcome. Methods： Totally, 32 patients with lateral end clavicle fracture （Neer＇s Type ll） were included in the study. After the informed consent and preoperative investigations were obtained, open reduction and intemal fixation was done using a 3.5 mm precontoured superior locking plate with lateral extension under general anesthesia. Postoperative X-rays were done on day I and every 6 weeks after operation, until radiological union was achieved. The postoperative pain was assessed using Visual Analogue Scale （VAS） on postoperative days 1, 2 and 10. Postoperatively arm pouch sling was given for 2 weeks followed by active mobilization. Patients were asked to do their daily routine work and avoid lifting heavy weights. The functional outcome was assessed at the end of 2nd and 6th months with the help of Disabilities of the Arm, Shoulder and Hand （DASH} scoring. Results： There were no intraoperative complications in the procedure. The mean VAS score on post- operative day 1 was found to be 5 which decreased to 3 on day 2 and 0 on day 10. The mean DASH score was calculated as 11.63 at the end of postoperative month 2 and then 4.6 at the end of month 6. There was one case of malunion in whom the overhead abduction was restricted but was not painful and was managed conservatively. Conclusion： The precontoured locking plates with lateral extension may be a good method to fix the fractures of the lateral end clavicle, which provide a stable fixation with good functional outcome with very few instances of stiffness and decreased range of motion of the shoulder with the hook plates and failure of fixation in screw and K-wire fixations. It may well be the answer to the fixation questions of the lateral clavicle fractures, although larger comparative studies between the surgical treatment methods are required to confirm the same.