Sample size estimation and statistical analysis
MHI, knee joints
SECONDARY, OBESE
ROM was used as the primary outcome, and the attainment value of ROM at 6 weeks was 120°, referring to the patient's rehabilitation schedule (2019 version) after ACL reconstruction in the sports medicine department of Peking university third hospital. Previous studies have mostly grouped knee joints at a group distance of 10° when evaluating their functional status (The sample size of each group was calculated to be 48. Considering that the rate of missing secondary follow-up was about 20%, the total sample size was set to 120.The data in the text and figures are presented as the mean (SD) or median (interquartile range). A modified intention-to-treat analysis was performed that included all patients who were randomized for treatment and attended at least two test sessions. Normality was checked for each variable. The group characteristics of the two groups were compared with a The subjective outcomes were analyzed using a multilevel analysis (SPSS version 24). A random intercept and slope model were used where repeated measurements (level 1) were nested within individual patients who underwent ACL reconstruction (level 2). After that, the following explanatory variables were added to the model: group [MHI and CON (as reference)], time [before surgery (as reference) and 2 and 6 weeks after surgery], and group-by-time interaction. The parameters of the multilevel model were estimated using the maximum-likelihood method. Only models with significantly better log-likelihood values were retained. The secondary outcomes were separately analyzed for the questionnaire and clinical indexes.Additional multilevel analyses were performed to examine whether sex, BMI, ROM of the non-injured leg, and age affected the recovery after ACL surgery. The multilevel model was identical to the model mentioned above, with the exception that the explanatory variable group was replaced by sex (male or female), BMI (normal, underweight, overweight, or obese), and age (old or young). For age, the patients in the old group were ≥ 30 years old, and those in the young group were < 30 years old. The BMI was < 24 kg/m