Articular cartilage injury is common in orthopedics. Improper exercises and physical trauma can lead to the injury of cartilage. Since articular cartilage lacks blood supply, once damaged, it is difficult for the cartilage to repair itself. If not treated effectively, cartilage injuries will develop into severe osteoarthritis affecting the whole joint. Arthroscopic microfracture technique can achieve better therapeutic effects than regular joint debridement, with simple procedures, minimal invasion, and low cost. However, the microfracture technique is limited by the patients′ age (under 45 years old) and the size of the cartilage defect area (less than 4 cm 2) Additionally, postoperative patients need to conduct strict and long-term rehabilitation trainings. Generally speaking, the short-term prognosis of microfracture is satisfactory. However, the repair tissue is mainly composed of fibrocartilage, which is inferior to hyaline cartilage because of its poor mechanical properties and anti-wear abilities. Therefore, the long-term effect is controversial. To conclude, arthroscopic microfracture is a recommended method for young patients with small cartilage defect areas, but its exact long-term clinical effects still need to be verified by further research. This paper reviews the operation protocol, clinical efficacy, and the mechanism of arthroscopic microfracture surgery, and aims to provides theoretical basis for its application in clinical treatment.

Objectives:To compare the clinical efficacy between robot-assisted cortical bone trajectory screw(RCBTS)and robot-assisted pedicle screw(RPS)for patients with lumbar spinal stenosis(LSS)undergoing sin-gle-level decompression and fusion.Methods:In this retrospective cohort study,LSS patients who underwent robot-assisted single-level decompression and fusion in Beijing Shijitan Hospital between June 2020 and June 2022 were reviewed.A total of 99 patients were included and divided into RCBTS group of 41 patients and RPS group of 58 patients.There were 59 males and 40 females,with an average age of 67.07±4.65 years old.The incision length,operative time,intraoperative blood loss,24h postoperative drainage,and postopera-tive hospital stay were compared between groups.The Japanese Orthopaedic Association(JOA)score and visual analogue scale(VAS)of low back pain were compared at 3d,3 months and 6 months after operation,and the fixed effects of JOA score and VAS score changes were tested.The screw positions were graded according to the Gertzbein-Robbins method.The accuracy of screw placement of the two surgical methods was evaluated by reviewing the postoperative imaging data.The perioperative and postoperative 3 months of complications were compared between the two groups.Results:There were no significant differences in baseline data be-tween the two groups(P＜0.05).Comparing with the RPS group,the RCBTS group was shorter in operative time(134.39±22.23min vs 152.93±19.10min,P＜0.001),smaller in incision length(64.93±3.71mm vs 78.84±3.82mm,P＜0.001),less in intraoperative blood loss(155.61±37.15mL vs 172.41±43.22mL,P=0.001)and postoperative drainage within 24h(83.66±21.54mL vs 101.21±29.80mL,P=0.002),and shorter in postoperative hospital stay(4.90±1.26d vs 6.26±1.66d,P＜0.001),with statistical significance.There was no significant difference in JOA score and VAS score changes between the two groups at each time point(P＞0.05).The fixed effect test showed that time was a fixed effect of JOA and VAS score changes(P＜0.001).The RCBTS group was no sig-nificantly different from the RPS group in the accuracy of screw placement(grade A:152/164 vs 211/232,P=0.538;grade B:9/164 vs 15/232,P=0.688;grade C:3/164 vs 6/232,P=0.619),the rate of clinically accept-able screw placement(161/164 vs 226/232,P=0.619),the rate of bad screw placement(3/164 vs 6/232,P=0.619),and the incidence of postoperative complications(only 1 patient in the RCBTS group developed delayed wound healing)(P＞0.05).Conclusions:Compared with RPS,RCBTS has significant advantages in operative time,incision length,intraoperative blood loss,volume of postoperative drainage,and postoperative hospital stay.However,there is no significant difference between the two groups in terms of postoperative functional recovery and alleviation in low back pain.