Objective:To explore the safety and early prognosis of robot assisted living donor kidney transplantation(KT)and plot the learning curve of mastering the operation.Methods:From July 2020 to March 2021, 30 cases of living robot assisted KT were completed.The follow-up period was 3 months.Cumulative sum analysis was performed for plotting the learning curve.According to the learning curve, they were divided into two groups of practice period(the first 17 cases)and proficiency period(the last 13 cases). Time of each operative stage and early prognosis were compared.Kidney function and perioperative complications of two groups were compared for evaluating the safety and effectiveness of robot assisted KT.Results:The average operative duration was (221.4±36.1)min.No intestinal obstruction, delayed graft function, urinary leakage and incision infection occurred during perioperative period.The average anal exhaust time was(1.9±0.2)days.During follow-ups, both pulmonary infection(2 cases)and acute rejection(1 case)improved after treatment.According to the learning curve, venous anastomosis(10 cases), arterial anastomosis(12 cases), warm ischemic time(12 cases)and ureteral anastomosis(17 cases)should be performed for reaching a proficiency level.An average of 15 operations was required for achieving proficiency throughout operations.Significant inter-group differences existed in operative duration [(235.5±31.6)vs(203.0±34.3)min, P=0.012] and warm ischemic time [(63.7±24.9)vs(47.0±11.3)min, P=0.033]. At some postoperative timepoints, creatinine of proficiency group was lower than that of practice group, such as Day 7 post-operation [(192.7±135.2)vs(107.8±27.9)μmol/L, P=0.022] and Day 30 post-operation [(147.8±46.3)vs(112.3±28.0)μmol/L, P=0.021]. However, no significant difference existed in estimated glomerular filtration rate at Day 7 post-operation [(56.1±34.1)ml/(min·1.73m 2)vs(72.0±18.5)ml/(min·1.73m 2), P=0.14] and Day 30 post-operation [(56.2±18.9)ml/(min·1.73m 2)vs(68.7±15.3)ml/(min·1.73m 2), P=0.14]. Conclusions:Robot assisted KT is both safe and feasible.And the learning curve requires 17 cases for reaching a proficiency level.

Objective To evaluate biomechanical properties of the nickel-titanium (NiTi) memory alloy stent and its in vitro biomechanical properties for lumbar interbody fusion. Methods The mechanical properties of the NiTi memory alloy stent were tested on mechanical testing machine. Moreover, lumbar interbody fusion was simulated on fresh lumbar specimens, and biomechanical properties of the NiTi memory alloy stent with matching bone graft for used for lumbar interbody fusion were analyzed and compared with the traditional box-shape cage. Results The maximum compressive strength of the NiTi memory alloy stent was ( 12 964 ± 962) N. The maximum deformation within the effective range of memory characteristics was (4. 68±0. 03) mm. The recovery rate of the NiTi memory alloy stent was up to 99. 86% . Compared with the intact lumbar model, the stability of the operative segment after the simulated lumbar interbody fusion using NiTi memory alloy stent alone was increased in the direction of anterior flexion, posterior extension, lateral flexion and rotation, which was equivalent to the box shape cage group (P>0. 05). After the combined use of autogenous bone granule and absorbable bone cement the ROM of the operative segment was further reduced (P<0. 05), which was equivalent to the box-shape cage+ unilateral posterior fixation group (P>0. 05). The pull-out strength of the NiTi memory alloy stent with matching bone graft group was significantly stronger than that of the box-shape cage group (P<0. 05). Conclusions The NiTi memory alloy stent in this study was designed with a matched bone granule-absorbable bone cement graft,which provided a new idea for the further optimization and development of lumbar interbody fusion. With excellent support and deformation properties, this NiTi memory alloy stent is biomechanical equivalent to the traditional box shape cage for lumbar interbody fusion, and can greatly improve the stability of surgical segment and the pull-out strength of implants after the combined use of autogenous bone granule and absorbable bone cement.

Objective To evaluate the biomechanical properties of lumbar interbody fusion with NiTi memory alloy stent-autogenous bone granule-absorbable bone cement. Methods The normal L3-5 segment finite element model (M0), L4-5 intervertebral fusion model with box fusion cage (M1), L4-5 intervertebral fusion model with NiTi memory alloy stent (M2) and L4-5 interbody fusion model with bone granule-absorbable bone cement for casting bone graft (M3) were constructed, respectively. The models were applied with mechanical loading to analyze the mechanical stability and the peak stress of L4 interior endplate. Results The range of motion (ROM) of L4-5 segment in M1 and M2 models was significantly lower than that of M0 model under flexion, extension, lateral flexion and axial rotation. In M3 model, the stability of the surgical segment was further improved and the peak stress of L4 interior endplate was much smaller than that of M1 and M2 models. Conclusions NiTi memory alloy stent and traditional box fusion cage have biomechanical equivalence when used alone in lumbar interbody fusion, and application of bone granule-absorbable bone cement for casting bone graft can further improve the stability and reduce the stress of endplate.