Study settings and patients
This is a randomized double-blind clinical trial conducted in the Hazrat Rasoul Hospital, Tehran, Iran. All individuals who had a complaint of shoulder pain during January 2014 to January 2017 were initially considered for the study. Individuals who had tendinitis or incomplete tear of the RC tendons, which was confirmed with MRI, had pain for more than 3 months, were older than 40 years old, and had a total of three positive tests out of the following five tests: neer, speed, full can, empty can, and the Hawkins test, were included in the study.
Those who were unwilling to enter the study or did not refer for follow-ups, those who did not follow the study protocol, had radicular pain, had signs of other pathologies including frozen shoulders or calcified tendinitis, those who had complete tear of RC tendons, had surgery during the past 6 months, had inflammatory diseases such as rheumatoid arthritis, fibromyalgia, polymyalgia rheumatica, and etc., had ligamentous laxity (a positive apprehension test or sulcus test), and those who had corticosteroid-based injections in the shoulder during the past 3 months, were excluded from the study.
These individuals were randomly selected to enter the study using simple random selection.
Individuals were classified into two groups of PRP and corticosteroid groups, using the permuted block randomization method. All randomizations were done by the Department of Sports Medicine at Iran University of Medical Sciences, Tehran, Iran.
During visit at related clinics, complete medical history on pain and specific data on functional problems of the shoulder were acquired. After which complete examination of range of motion of shoulder, specific tests related to tendon function within the RC and shoulder biceps were performed.
For evaluating the RC, each patient underwent MRI of the shoulder for confirmation of tendinopathy of shoulder. Tendinitis was considered when signal of the tendon changed while tendon was preserved. Incomplete tear of the tendon was considered a detachment of the tendon without including the whole thickness of the tendon.
Patients were then referred for ultrasonography. Tendons of the shoulder were evaluated by a specialist in sports medicine. Sonography was done using a Mindray M5 system (China) and by a 7L4s transducer.
All assessments were done by a single sports medicine specialist who was blinded to the grouping of patients, in order to minimize bias in measurements.
Definition of variables
For subjective evaluation of patients, the Western Ontario RC (WORC) and Disability of Arm-Hand-Shoulder (DASH) questionnaires were utilized. After detailed explanation, each individual filled in the questionnaires.
The WORC questionnaire is a measure of functional limitations in RC pathology. This index considers 5 variables in its assessment, including physical symptoms, physical activity, work, daily activity, and mentality and excitement. Each item is scored from 0 to 100, and the higher the score the worse the condition of the shoulder .
The DASH questionnaire is a measure of disability and includes 30 questions which assess individuals’ ability to perform daily activity, for example: ability to carry objects, writing, and other daily activities. Patients are scored from 0 to 100 and a higher score indicates a worse condition .
Pain was assessed using the Visual Analogue Scale (VAS) questionnaire. In this system of scoring, a picture is shown to the individual which is consequently scored from 0 to 10. The higher the number, the higher the severity of the pain .
Range of motion of shoulder was directly evaluated by a manual medical Goniometer (Dahi Teb, Iran) . Range of motion (ROM) of shoulder, abduction, adduction, forward flexion, internal and external rotation, and extension were assessed according to the Kendall method . Measurement of ROM was done by one trained expert in sports medicine. To reduce bias, all ROM tests were performed three times and mean of these measurement were considered for each individual.
Data on baseline characteristics, range of motion, WORC score, DASH score, and VAS score was obtained from each patient. The minimal detectable change (MDC) for the WORC, DASH, and VAS is reported to be 1.7 , 10.2 , and 0.08 , respectively, according to previous literature.
The PRP was prepared and processed in ROOYA GEN® (Arya Mabna Tashkhis Co., Tehran, Iran). For the corticosteroid injections, the Depo-medrol 40mg (Pfizer Inc., USA) was used.
For the administration of PRP or corticosteroid, patients were seated. After proper preparation, 3cc of PRP was injected within the intraarticular joint and another 3cc of PRP was injected at the site of the tendon tear, under guide of sonography .
For the corticosteroid group, 1cc of Depo-medrol 40mg and 1cc of lidocaine (2%) was injected within the subacromial joint similar to the PRP group.
After the injections, patients were asked to withdraw from using any non-steroidal anti-inflammatory drugs (NSAID). In cases with pain, they were allowed to use acetaminophen.
After the injections, both groups were given shoulder exercise and scapula dyskinesia regimens. Patients were blinded to the treatment groups and were unaware of the type of injections received.
Baseline information, medical history, and physical examination of patients were recorded during first visit. Patients were then visited 1 week, 1 month, and 3 months after administration of medication. In cases of pain or any complaint patient were able to either contact or refer to the sports clinic.
DASH and WORC scores were evaluated at baseline, 1 month, and 3 months post-intervention; however, other parameters including ROM and VAS were evaluated at five occasions of baseline, 1 week, 1 month, and 3 months post-intervention.
Thickness of the supraspinatus muscle was evaluated at baseline, 1 month and 3 months of follow-up.
All follow-ups were done by a single specialist in sports medicine who was blinded to the allocation of patients. A clinical trial nurse was appointed to remove any information from patients’ medical records prior to visitation by the assessor.
Pain using the VAS score.
Secondary end points
(1) Range of motion, (2) supraspinatus thickness, (3) WORC score, and (4) DASH score
Sample size calculation
Severity of pain, evaluated using the VAS questionnaire, was considered the primary outcome of the study. Correlation of VAS from beginning of the study to the end point was 0.4 (r = 0.4). For obtaining a statistical difference of 13 or more, and considering a standard deviation of 20 , type one error of 5% and a power of study of 80%, a minimum of 30 individuals were needed for each of the study groups.
All participants gave their written and informed consent to take part in the study. The study protocol was in coherence with the guidelines of the Declaration of Helsinki.
Data was analyzed using the SPSS software, for windows, version 23. All dependent variables were tested by Shapiro-Wilk test for normality. The assumption of normality was accepted when p value was >0.05. For comparison of qualitative data between groups, the chi-sqaure test and for comparison of quantitative data with normal distribution between two groups the independent t test was used. For comparison of scores during follow-ups, the ANOVA test (GLM Repeated measures test) was used.
A p value of less than 0.05 was considered statistically significant.