This study introduced the inverse probability weight and overlap weight by propensity score and how to test the balance and estimate the effect after weighting. Four R packages that can be used for propensity score weight analysis were introduced and compared.
Randomized controlled trials (RCTs) are often limited because of ethical or operational reasons. Quasi-experimental studies could be an alternative to RCTs to make causal inferences without randomization by controlling the confounding effects of the study. This paper introduced the general statistical analysis methods of quasi-experimental design through basic ideas, characteristics, limitations and applications in medicine, including difference-in-difference models, instrumental variables, regression discontinuity design, interrupted time series, and so on, and to provide references for future research.
ObjectiveTo investigate the effectiveness of arthroscopic GraftLink technique reconstruction combined with suture anchor fixation in treatment of anterior cruciate ligament (ACL) rupture and medial collateral ligament (MCL) grade Ⅲ injury.MethodsBetween June 2015 and February 2018, 28 patients with ACL rupture and MCL grade Ⅲ injury were treated. Arthroscopic GraftLink technique was used to reconstruct ACL with autologous peroneus longus tendon (PLT), and suture anchor fixation was used to repair MCL. There were 22 males and 6 females, aged 21-47 years, with an average age of 30.4 years. The cause of injury included traffic accident in 18 cases, falling from height in 7 cases, and sports injury in 3 cases. The time from injury to admission was 1-2 weeks, with an average of 1.3 weeks. The preoperative Lysholm score of knee joint was 46.8±3.0 and the International Knee Documentation Commission (IKDC) score was 49.2±2.7. The American Orthopaedic Foot and Ankle Society (AOFAS) score of ankle joint was 98.29±0.72. Both Lachman test and valgus stress test were positive. There were 8 cases of meniscus injury and 2 cases of cartilage injury.ResultsThe operation time ranged from 55 to 90 minutes, with an average of 72.5 minutes. All incisions healed by first intention after operation, and no complications related to operation occurred. All patients were followed up 6-38 months, with an average of 20.7 months. At 3 months after operation, the range of motion of the knee joint was 116- 132°, with an average of 122°. Lachman test showed that the anterior translation more than 5 mm in 2 cases, and the others were negative; while the valgus stress test showed that all patients were positive. At 6 months after operation, the Lysholm score and IKDC score of knee joint were 90.2±1.8 and 93.5±2.3, respectively, which were significantly higher than preoperative scores (t=31.60, P=0.00; t=29.91, P=0.01); AOFAS score of ankle joint was 97.86±0.68, with no significant difference compared with preoperative score (t=2.89, P=0.08). KT-1000 test showed that the difference of anterior relaxation between bilateral knee joints was less than 2 mm in 25 cases and 3 to 5 mm in 3 cases.ConclusionThe method of ACL reconstruction via arthroscopic GraftLink technique with PLT and MCL repair via suture anchor fixation has the advantages of less knee injury and faster recovery, and there is no significant impact on ankle function after tendon removal.