Cumulative sum analysis score and phacoemulsification competency learning curve

AIM： To use the cumulative sum analysis score（CUSUM） to construct objectively the learning curve of phacoemulsification competency.METHODS： Three second-year residents and an experienced consultant were monitored for a series of 70 phacoemulsification cases each and had their series analysed by CUSUM regarding posterior capsule rupture（PCR） and best-corrected visual acuity. The acceptable rate for PCR was 〈5%（lower limit h） and the unacceptable rate was 〉10%（upper limit h）. The acceptable rate for bestcorrected visual acuity worse than 20/40 was 〈10%（lower limit h） and the unacceptable rate was 〉20%（upper limit h）. The area between lower limit h and upper limit h is called the decision interval. RESULTS： There was no statistically significant difference in the mean age, sex or cataract grades between groups. The first trainee achieved PCR CUSUM competency at his 22 nd case. His best-corrected visual acuity CUSUM was in the decision interval from his third case and stayed there until the end, never reaching competency. The second trainee achieved PCR CUSUM competency at his 39^ th case. He could reach best-corrected visual acuity CUSUM competency at his 22 ^nd case. The third trainee achieved PCR CUSUM competency at his 41 st case. He reached bestcorrected visual acuity CUSUM competency at his 14 ^th case.CONCLUSION： The learning curve of competency in phacoemulsification is constructed by CUSUM and in average took 38 cases for each trainee to achieve it.

Anterior vertebral body tethering for idiopathic scoliosis in growing children:A systematic review

BACKGROUND The management of idiopathic scoliosis(IS)in skeletally immature patients should aim at three-dimensional deformity correction,without compromising spinal and chest growth.In 2019,the US Food and Drug Administration approved the first instrumentation system for anterior vertebral body tethering(AVBT),under a Humanitarian Device Exception,for skeletally immature patients with curves having a Cobb angle between 35°and 65°.AIM To summarize current evidence about the efficacy and safety of AVBT in the management of IS in skeletally immature patients.METHODS From January 2014 to January 2021,Ovid Medline,Embase,Cochrane Library,Scopus,Web of Science,Google Scholar and PubMed were searched to identify relevant studies.The methodological quality of the studies was evaluated and relevant data were extracted.RESULTS Seven clinical trials recruiting 163 patients were included in the present review.Five studies out of seven were classified as high quality,whereas the remaining two studies were classified as moderate quality.A total of 151 of 163 AVBT procedures were performed in the thoracic spine,and the remaining 12 tethering in the lumbar spine.Only 117 of 163(71.8%)patients had a nonprogressive curve at skeletal maturity.Twenty-three of 163(14.11%)patients required unplanned revision surgery within the follow-up period.Conversion to posterior spinal fusion(PSF)was performed in 18 of 163(11%)patients.CONCLUSION AVBT is a promising growth-friendly technique for treatment of IS in growing patients.However,it has moderate success and perioperative complications,revision and conversion to PSF.

Flow Stress Behaviors and Microstructure Evolution of 300M High Strength Steel under Isothermal Compression

The compressive deformation behaviors of 300M high strength steel were investigated over a wide range of temperatures （850- 1200 C） and strain rates （0. 001- 10 s^- 1 ） on a Gleeble-3800 thermo-mechanical simulator. The measured flow stress was modified by the corrections of the friction and the temperature compensations, which nicely reflect negative effects of the friction and temperature on the flow stress. The corrected stress-strain curves were the dynamic recrystallization type on the conditions of higher deformation temperature and lower strain rate. Flow stress increases with the increase of strain rate at the same deformation temperature and strain. By contrast, flow stress decreases with the increase of temperature at the same strain rate and strain. Dependence of the peak stress on temperature and strain rate for 300M steel is described by means of the conventional hyperbolic sine equation. By re gression analysis, the activation energy （Q） in the whole range of deformation temperature is determined to be 367. 562 kJ/mol. The effects of the temperature and the strain rate on mierostructural evolution are obvious. With the increase of the deformation temperature and the decrease of the strain rate, the original austenite grain sizes of 300M steel increase. At the same time, the corrected flow stress curves more accurately determine the evolution of the microstrueture.