From January 2014 to December 2018, a total of 100 FAI patients who underwent HAS in The First Affiliated Hospital of Nanchang University were consecutively recruited in this study. The patients were eligible if they met the following conditions: (1) diagnosed as FAI according to clinical signs (such as impingement either due to slipped capital femoral epiphysis, acetabular retroversion or coxa profunda, or decreased femoral head-neck offset) and imaging assessment (including radiographs, computed tomography (CT) scan or magnetic resonance imaging (MRI) arthrogram); (2) about to receive HAS; (3) age ≥ 18 years old; (4) no history of hip surgery or interventional therapy. The following patients were excluded: (1) diagnosed as hip osteoarthritis; (2) bilateral lesions; (3) intra-articular treatment with corticosteroid or hyaluronic acid injection in the past 3 months; (4) received analgesic drugs within 7 days before enrollment; (5) hypersensitivity to the study medications (celecoxib or pethidine); (6) hepatic, renal, pancreatic, gastrointestinal, or blood coagulation disorders; (7) pregnancy or lactating woman. This study was approved by the Ethics Committee of The First Affiliated Hospital of Nanchang University in August 2013. All the patients signed informed consents before enrollment.
All eligible patients were randomly allocated to preemptive analgesia group (N = 50) or postoperative analgesia group (N = 50) as 1:1 ratio. The randomized list was designed by Shanghai Qeejen Institution (Shanghai, China), and the randomization code of patients was generated using blocked randomization method (block length was 6) using SAS 9.0 software (Statistical Analysis System, Cary, USA). When a patient was eligible, an email including patient information was sent to Shanghai Qeejen Institution (Shanghai, China), then a unique subject identification number for the patient was provided by Shanghai Qeejen Institution (Shanghai, China). According to identification numbers, the patients were assigned to corresponding groups and received relevant treatment protocols.
All patients underwent HAS method as described in a previous study (Domb et al. 2012). For preemptive analgesia group, all patients received celecoxib as follows: 400 mg (oral) at 24 h prior to operation, 200 mg (oral) at 12 h and 2 h prior to operation, and then 200 mg (oral) twice a day from 12 h post-operation to day 7 post-operation. For postoperative analgesia group, patients received celecoxib 400 mg (oral) at 12 h post-operation, then 200 mg (oral) twice a day until 7 days post-operation. Within 7 days post-operation, if patients suffered from intolerable pain, they were allowed to receive rescue analgesia with pethidine, and the dosage of used of pethidine was recorded. To prevent heterotopic ossification, all the patients received celecoxib 200 mg (oral) per day from day 8 to month 1 post-operation.
The baseline characteristics including age, gender, side of lesions and FAI type were recorded for each patient. Pain visual analog scale (VAS) score (0–10, 0 indicating no pain, 10 indicating the intolerable pain) and PGA score (0–10, 0 indicating very well condition, 10 indicating worst condition) were evaluated prior to operation, then the postoperative assessments of pain VAS score and PGA score were performed on day 1, day 2, day 3, day 7, at month 1 and month 3, respectively. Harris hip score was assessed before operation, then on day 7 post-operation, at month 1 and month 3 post-operation, respectively. Harris hip score was used to evaluate the function recovery of hip, covering pain (1 item, scored 0–44 points), function (7 items, scored 0–47 points), absence of deformity (1 item, scored 4 points), and range of movement (2 items, scored 5 points), and the maximum Harris hip score was 100 (best possible outcome) (Harris 1969). Besides, the consumption of rescue-use pethidine within 3 days operation and within 7 days post-operation was also recorded, respectively.
Sample size calculation
To calculate the required sample size, we assumed that the mean pain VAS score and standard deviation (SD) on day 3 post-operation was 5.0 ± 1.5 in preemptive analgesia group and 6.0 ± 1.5 in postoperative analgesia group. Based on the assumed pain VAS score of each group, the required sample size was 42 in each group using a two-sided two-sample t test, 5% level of significance (α) and a power of 0.85, which was calculated by PASS V11.0 software (NCSS, Kaysville, UT, USA). While considering that there was at least 10% attrition rate, the sample size was finally increased to 50 in each group.
Based on intention-to-treat (ITT) principle, all patients were included in the final analysis. As for patients who lost follow up or withdrew from the study, the data at the last follow-up were used as the values of each later missing visit. Continuous variables were presented as mean and standard deviation (SD), categorical variables were displayed as count (percentage). Comparisons between groups were determined by Student’s t test or Chi-square test. Data analyses were performed using SPSS 24.0 (IBM, Chicago, USA), and figures were plotted using GraphPad Prism 7.00 (GraphPad Software, San Diego, USA). All tests were two-sided, and P value < 0.05 was considered as significant.