ABSTRACT
In order to meet the clinical requirements of spine surgery, this paper proposes the fabrication of the customized template for spine surgery through computer-aided design. A 3D metal printing-selective laser melting (SLM) technique was employed to directly fabricate the 316L stainless steel template, and the metal template with tiny locating holes was used as an auxiliary tool to insert spinal screws inside the patient's body. To guarantee accurate fabrication of the template for cervical vertebra operation, the contact face was placed upwards to improve the joint quality between the template and the cervical vertebra. The joint surface of the printed template had a roughness of Ra = 13 ± 2 µm. After abrasive blasting, the surface roughness was Ra = 7 ± 0.5 µm. The surgical metal template was bound with the 3D-printed Acrylonitrile Butadiene Styrene (ABS) plastic model. The micro-hardness values determined at the cross-sections of SLM-processed samples varied from HV0.3 250 to HV0.3 280, and the measured tensile strength was in the range of 450 MPa to 560 MPa, which showed that the template had requisite strength. Finally, the metal template was clinically used in the patient's surgical operation, and the screws were inserted precisely as the result of using the auxiliary template. The geometrical parameters of the template hole (e.g., diameter and wall thickness) were optimized, and measures were taken to optimize the key geometrical units (e.g., hole units) in metal 3D printing. Compared to the traditional technology of screw insertion, the use of the surgical metal template enabled the screws to be inserted more easily and accurately during spinal surgery. However, the design of the high-quality template should fully take into account the clinical demands of surgeons, as well as the advice of the designing engineers and operating technicians.
ABSTRACT
OBJECTIVE: to explore the outcomes between the early or delayed air drainage for spontaneous pneumothorax. METHODS: the present prospective study was designed to evaluate the efficacy and complications. 242 patients with primary spontaneous pneumothorax were randomly allocated to early (< 72 h) group (n = 142) or delayed (> 6 d) exhaust air group (n = 122), the recent success rates, average time in hospital, recurrences rates, and pleura adhesion rates were evaluated. RESULTS: average time in hospital: early group and delayed group respectively was (18 ± 6) d vs (6 ± 2) d. In early group, the amount of pneumothorax was between 20% to 50%, 51 cases were aspirated and 44 of them were increased after first aspiration, whom were subsequently treated by intercostal drainage. Size of pneumothorax more than 50%, 98 patients treated by intercostal drainage.12 of 142 patients with persistence leak air transferred to surgery. In delayed group, all of 122 aspirations were successful at the first time. There were significant differences between the 2 groups in recent successful rate. 29 of the 128 patients in early group and 5 of the 115 had a relapsing pneumothorax. During the 2 year follow-up period, 79 of the 128 patients in early group and none of the 115 had radiographic pleural adhesions appearances. CONCLUSION: the time of air drainage was associated with outcomes of primary spontaneous pneumothorax. These data suggest that delayed intervention is an effective initial treatment strategy for patients with PSP, with a shorter time in hospital, fewer pleural adhesions and lower recurrence rates.
