Is low dose dextrose prolotherapy as effective as high dose dextrose prolotherapy in the treatment of lateral epicondylitis?- a double-blind- ultrasound-guided- randomized controlled study

Lateral epicondylitis is an enthesopathy that occurs at the junction of the forearm extensor muscles to the lateral epicondyle of the humerus. It is the most common cause of pain in the lateral elbow. It is more common in females, in the dominant hand, and in the 3rd-5th decades. Repetitive supination and pronation of the forearm and overuse of the wrist extensor muscles are considered the most important causative factors. The main symptoms are; elbow pain that may radiate to the forearm or upper arm. Tenderness and pain in the lateral epicondyle, weakening of handgrip strength, and limitation in activities of daily living can be observed. First-line treatment is conservative treatment and includes rest, bracing, physical medicine modalities, and injection treatments. Among the injection therapies, prolotherapy injections are gained importance in recent years and have low side effects and cost. Prolotherapy is a regenerative treatment method applied by injection of osmotic/irritant solutions to painful ligaments, tendon attachments, and joint spaces that activate inflammation. Usage of lower doses than 10% dextrose solutions, it is thought that proliferation without inflammation can occur in the cells and tissues. In this randomized controlled, double-blind study, we aimed to investigate the effectiveness of prolotherapy injection on clinical improvement, pain, handgrip strength, pressure pain threshold, functionality, to determine the results of the injection at the 12th week and to compare the efficacy and side effects between 5% low dose dextrose and 15% high dose dextrose prolotherapy in the treatment of chronic lateral epicondylitis. A total of 60 patients, 39 women, and 21 men, with chronic lateral epicondylitis, were included in the study. Patients were randomized into 3 groups. Of the groups determined randomly; Group 1 with 5% dextrose solution (5% Dextrose PrT), Group 2 with 15% dextrose solution (15% Dextrose PrT), and group 3 with 0.9% saline solution, injections were done three times (at week 0, week 3, and week 6), with an interval of 3 weeks. The injection was performed to the entheses of the forearm extensors and the annular ligament, using 1 ml of the solution under the guidance of musculoskeletal system ultrasound. All patients were given a home exercise program. Age, gender, occupational information, comorbidities, medications, history of surgery, dominant hands, extremity on the affected side, duration of symptoms were recorded. The patients were evaluated with clinical parameters (handgrip strength, pressure pain threshold, VAS-I, VAS-A, Quick-DASH) at 0, 3, and 12 weeks. The Disease Global Assessment questionnaire was used at weeks 3 and 12. The side effects and complications were followed up. The mean age of all patients participating in the study was 44.30±10.31 years, 65% (n=39) were female and 35% (n=21) were male. 93.3% of the patients had the right dominant side and the rate of involvement of the right dominant arm was 76.6%. There was no statistical difference between the groups in terms of age, gender, duration of complaint, dominant and affected side, occupation (p>0.05). There was no difference between the groups in VAS-I, VAS-A, Quick-DASH, and algometer values before treatment (p>0.05). VAS-I and VAS-A; In group 2, the decrease at the 3rd week was significantly higher than the other groups (p<0.05). In VAS-I, there was no difference between Groups 1 and 3 at week 3 (p>0.05). While there was no significant difference in VAS-I between Groups 1 and 2 at 12 weeks (p>0.05), the decrease in this value was statistically significant in both groups compared to Group 3 (p<0.05). There was a significant decrease in VAS-A at the 12th week compared to the 0th week and in between the 3rd and 12th weeks in Group 1 (p<0.05). In group 3, there was no significant difference in pre-and post-treatment VAS-I, VAS-A, handgrip strength (p>0.05). Handgrip strength; There was no difference between the groups at 0 and 3 weeks (p>0.05). There was a significant increase in handgrip strength in Group 2 compared to the other groups at the 12th week (p<0.05). There was a significant increase in handgrip strength in the 3rd and 12th weeks compared to the 0th week in Group 1 (p<0.05). Algometer score; There was a significant decrease in the 3rd and 12th weeks compared to the 0th week in Groups 1 and 2 (p<0.05). While there was no significant difference in Group 1 and 2 at week 3, there was a significant difference in Group 2 at week 12 (p<0.05). There was a significant difference between week 0 and week 12 in algometry score in group 3 (p<0.05). In the Quick-DASH score; There was a significant difference in Group 1 and 2 compared to Group 3 at the 3rd and 12th weeks. There was a significant decrease in the 3rd and 12th weeks compared to the 0th week in Groups 1 and 2 (p<0.05). There was a statistically significant difference in the Disease Global Assessment score at the 3rd and 12th weeks in Groups 1 and 2 compared to Group 3 (p<0.05). There was no significant difference between the groups in terms of side effects and complications (p>0.05). As a result, in the chronic lateral epicondylitis treatment, 5% and 15% Dextrose PrT is more effective in pain reduction, increasing handgrip strength and functionality than %0,9 saline injection. 15% Dextrose PrT was more effective in handgrip strength increase and algometer scores at the week 12 and the early period (week 3) in resting and activity pain than 5% Dextrose PrT. There was no statistical difference in Quick-DASH and Disease Global Assessment scores, side effects, and complications between the two PrT groups. Based on this study we recommend 15% Dextrose PrT injections for the treatment of lateral epicondylitis. However, there is a need for studies comparing prolotherapy injection doses and supporting long-term follow-ups.