Comparison of the effectiveness of extensor muscle strengthening exercise by itself, exercise with polydeoxyribonucleotide injection, and exercise with extracorporeal shockwave therapy in lateral epicondylitis: a randomized controlled trial

Abstract

Background: Extensor muscle strengthening exercises with counterforce braces (EX) is a conventional conservative treatment for lateral epicondylitis (LE) of the elbow. In addition, polydeoxyribonucleotide (PDRN) or extracorporeal shockwave therapy (ESWT) has been recently used for LE.

Methods: Sixty-three patients with chronic LE participated in this study and randomly allocated in three groups (G1: EX, G2: EX+PDRN injection, and G3: EX+ESWT). All of the three groups were taught to perform EX at the first out-patient department (OPD) visit. Group 2 was injected with 3 mL PDRN (5.625 mg/3 mL), while group 3 received ESWT at the first OPD visit. Visual analog scale pain score, Mayo elbow performance score (MEPS), and ultrasonographic examination were checked before, 6 weeks, and 12 weeks after the treatments.

Results: Overall functional scores and ultrasonographic findings in all three groups improved after treatment. The mean MEPS in group 2 improved more than groups 1 and 3 at 6 weeks (G1, 56.9>62.4; G2, 54.3>65.0; G3, 55.7>62.6), and more than group 1 at 12 weeks (G1, 56.9>67.9; G2, 54.3>73.6). The mean common extensor tendon depth (CETD) on ultrasonography in group 2 increased more than groups 1 and 3 at 6 and 12 weeks (6 weeks: G1, 0.385>0.386; G2, 0.332>0.392; G3, 0.334>0.357; 12 weeks: G1, 0.385>0.409; G2, 0.332>0.438; G3, 0.334>0.405 [cm]).

Conclusions: PDRN injections combined with EX exhibited a greater improvement in mean MEPS and mean CETD compared to EX only or EX combined with ESWT for LE within the 12 weeks follow-up.

Keywords: Counterforce brace; Extensor muscle strengthening exercise; Extracorporeal shockwave therapy; Lateral epicondylitis; Polydeoxyribonucleotide.

Fig. 1.

Flow diagram of this study. EX: extensor muscle strengthening exercises with counterforce braces, US: ultrasound, PDRN: polydeoxyribonucleotide, ESWT: extracorporeal shockwave therapy.

Fig. 2.

The grading of the color Doppler activity (CDA) on longitudinal ultrasonographic examinations of the common extensor tendon origin. The grading was performed in the region of interest (ROI) defined as a 0.5 cm longitudinal part of the tendon with maximum CDA. A horizontal green line measuring 0.5 cm marks the superficial border of the ROI, white dotted lines mark the proximal and distal borders, and the bone marks the deep border. Flow towards the transducer is depicted in red while flow away from the transducer is shown in blue. (A) G0, no activity. (B) G1, single vessel in the ROI. (C) G2, CDA in <25% of the ROI. (D) G3, CDA in 25%–50% of the ROI. (E) G4, CDA in >50% of the ROI. R: radial head, L: lateral epicondyle.

Fig. 3.

The common extensor tendon depth (CETD) and the common extensor tendon tear thickness (CETTT) on longitudinal ultrasonographic examinations. (A) CETD. (B) CETTT. R: radial head, J: radiohumeral joint, D: dotted line indicates tendon depth, P: plateau, L: lateral epicondyle, CETO: common extensor tendon origin, T: CETTT.

Fig. 4.

Strengthening exercise of the extensor muscle of the elbow. (A) All the fingers and wrist were fully extended, and isometric force was applied for 10 seconds. (B) A period of rest was followed for 10 seconds with all the fingers slightly flexed and the wrist neutral.

Fig. 5.

The ultrasonographic follow-up of the three groups. (A) Group 1 at initial. Color Doppler activity (CDA), grade 2; common extensor tendon depth (CETD), 4.3. (B) Group 1 at 12 weeks. CDA, grade 2; CETD, 4.4 mm. (C) Group 2 at initial. CDA, grade 2; CETD, 4.2 mm. White arrow indicates a suspicion of a partial thickness tear of the common extensor tendon. (D) Group 2 at 12 weeks. CDA, grade 1; CETD, 4.5 mm. (E) Group 3 at initial. CDA, grade 1; CETD, 3.8 mm. (F) Group 3 at 12 weeks. CDA, grade 0; CETD, 4.0 mm.