In this study, we performed a retrospective and prospective study of preoperative predictors of the length of stay (LOS) in three groups of surgical patients and conducted a clinical retrospective study of the current research status of preoperative predictors of LOS prolongation in three groups of patients under ERAS (enhanced recovery after surgery) mode, such as patient characteristics and comorbidities. Information such as patients’ exercise preferences, exercise time, frequency and duration, footwear, location of knee osteoarthritis, whether there is a past history of knee injury, and smoking and drinking history was collected, and the research data of 312 patients undergoing the three operations were analyzed by SPSS. Meniscal injury-knee arthroscopy sample included a total of 104 people. Surgical sample for anterior cruciate ligament reconstruction included a total of 100 subjects. Knee osteoarthritis-knee replacement surgery sample included 148 people who were divided into two groups in a ratio of 1 : 1: one group used Mailuo Shutong pills during hospitalization (intervention group) and the other group did not (control group). The research conclusions are as follows. Meniscal Knee Arthroscopy. (1) Samples from different causes of injury showed significant differences for all injured sites. (2) Samples with different smoking and drinking histories all showed significant differences for the causes of injury. (3) Exercise hobby, exercise frequency, duration of each exercise and duration of exercise, and warm-up time before exercise all showed positive correlation. Anterior Cruciate Ligament Reconstruction Surgery. (4) Samples from different causes of injury showed significant differences for all the injured sites. (5) Age has a significant negative influence on the wearing of shoes at ordinary times. (6) Exercise hobby: the warm-up time before exercise had a significant negative influence on the injured area. (7) Two groups of analysis items of exercise frequency, exercise duration and exercise duration, preexercise warm-up time, and exercise hobby were typically positively correlated. Total Knee Arthroplasty. (8) There was a significant difference of 0.01 between the hospitalization days of the intervention group and the control group (
p
<
0.01
), and the hospitalization days of the intervention group were significantly lower than those of the control group. These results indicated that Mailuo Shutong pills were of great significance for the treatment of orthopedic patients during the operation period in that it could effectively shorten the hospital stay of all orthopedic patients and strengthen the accelerated rehabilitation. (9) There was a significant positive correlation between the history of knee joint surgery and the use time of Mailuo Shutong pills. (10) There was a markable positive correlation between occupation and sports hobbies, sports time, frequency and duration, and footwear. There was a significant negative correlation between occupation and preexercise warm-up. (11) Exercise time, frequency, and duration have significant positive influence on BMI.