A prospective randomized clinical trial was conducted from November 2017 to July 2018. An institutional review board approval from the Ethics Committee of the Universidade Federal de Minas Gerais was obtained for our research protocol to prospective data acquisition (CAAE:11677714.4.0000.5149), and an informed consent was signed by all the participants or one person responsible for them.
The sample size was calculated to test the hypothesis that a differentiated education would increase post-operative range-of-motion (ROM) of the knee joint (primary outcome). Trying to detect a difference of 10 degrees in ROM of the knee joint between groups and based on a power test of 80% and a confidence interval of 5% after assuming a possible 10% lost in follow-up, 15 patients in each group were considered the minimum number of participants.
Secondary outcomes were:
- the Short Form Health Survey (SF-36), which includes questions about patients general health
- the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) - results range from 0 to 96. It evaluates pain intensity (0-20), stiffness (0-8) and function (0-68)
- the visual analogue pain scale (VAS) - ranging from 0 to 10
- the distance the patients were able to walk and in the last follow-up if they were able to walk 400 meters or more
- the capacity to climb and descend stairs.
All variables were collected in the preoperative appointment which occurred at least 2 weeks before surgery and in the post-operative evaluations.
Inclusion criteria: patients with unilateral symptomatic primary or secondary OA of the knee, older than 45 years, with indication of a primary TKA, who signed the informed consent form. Clinical examination and functional tests were applied to all participants by two investigators (DGKB, DSL).
Patients were then randomized into two groups: differentiated orientation or usual orientation. Randomization comprised choosing one of two closed envelopes with the words "usual" or "differentiated", referring to the approach it would be done.
Intervention group (45 patients): after medical appointment, patients received a new multidisciplinary reinforced orientation that included scheduled sessions of lectures done by an orthopedic surgeon, a nurse and a physiotherapist concerning the pre and post-operative care, pain management, rehabilitation exercises to gain ROM, the basic steps of the surgical procedure and the importance of walking with a walker. This intervention was done 2 weeks before surgery during office consultation. Patients were invited to attend a collective oral session, which included a standardized sequence of slides and images regarding the pre-operative preparation, the procedure itself and the rehabilitation with 1) a 15-minute lecture done by a nurse, 2) a 15-minute lecture done by a physiotherapist and 3) a 15-minute lecture done by an orthopedic surgeon, followed by additional time for patients to ask questions. Researchers also provided a phone contact number in case patients had further questions. The cost of this intervention method is low, which turns it feasible to be applied more widely (FIGURE 1).
Control group (34 patients): patients were oriented during conventional medical appointments, in which any doubts were clarified. A phone contact of researchers was provided for the patients.
The difference in the number of participants between groups was due to the study closure before 50 patients in each group were reached, considering that the minimal number to confirm our hypothesis was 15 patients.
The post-operative clinical and functional evaluation was performed by three blinded investigators (MVTR, TFGM, FSM). The study was conducted at the Orthopaedic Department of the Federal University of Minas Gerais – Brazil.
Seventy-nine patients were eligible for the study. Twelve were excluded during follow-up - 5 in the control group and 7 in the intervention group: one patient died (myocardial infarct), three patients had periprosthetic joint infection and eight did not return for control and were excluded. After exclusions, the control group and the intervention group remained with 29 and 38 patients, respectively (FIGURE 2).
All patients were operated on in the same Institution by three different surgeons (MAPA, GMAS, TVOC) who followed the same protocol. Patients received a peridural anesthesia with bupivacaine (0,5%) and intravenous sedation (Diprovan® AstraZeneca). Tourniquet was applied in all cases set to 300 mmHg. Primary TKA was performed through a classical medial arthrotomy with patellar eversion. A cruciate retained implant (Nexgen® Zimmer – Warsaw, IN), with patellar substitution, fixed with a non-impregnated antibiotic cement was used in all cases. Postoperative multimodal pain control protocol was made in both groups and started on the same day of the procedure. It consisted of scheduled 1) acetaminophen 133 mg every 6 hours, 2) metamizole 500 mg every 6 hours, 3) tramadol 50 mg every 8 hours for 24 hours and 4) morphine 2 to 6 mg every 4 hours, as needed. Patients were encouraged to start early ROM and weight bearing with a walker on the first day. Patients were discharged from hospital on day 2 or 3 and were evaluated in 15 days, 1 month, 3 months and 6 months after surgery and in each session, the scores and the VAS were applied, ROM was evaluated with a calibrated goniometer, and specific questions such as the use of walker or cane, their ability in climbing or descending stairs and the distance they were able to walk were asked.
Statistical analysis was performed to determine statistically significant differences between the 2 groups (p < 0.05), using appropriate software (G*Power Version 3.1.9.2) and included analysis of distribution by Zolmogorov-Smirnov test. Independent T-test was used to analyze numerical, continuous and normally distributed variables. Qui-square test was used for categorical data. No crossover was observed, so intention-to-treat analysis was not performed.