Efficacy of ultrasound-guided hyaluronic acid injections in achilles and patellar tendinopathies: a prospective multicentric clinical trial

Background. Achilles and patellar tendinopathies are common causes of chronic pain and functional impairment. Conservative management can be effective, but it is time-consuming and it requires intensive patient compliance. Hyaluronic acid (HA) is a key component of the extracellular matrix and its anti-inflammatory, lubricant and analgesic properties are well documented in osteoarthritis. Growing pre-clinical studies indicate a possible role of HA in tendon pathology, while clinical evidences are still lacking. Objectives. The primary objective was to assess the efficacy of a new formulation of HA obtained from biofermentation (Hyalotend (R) Fidia Farmaceutici, Italy) to improve the clinical symptoms assessed by the VISA-A and VISA-P questionnaires at 90 Days of follow-up. Secondary objectives were to evaluate improvement in pain (NRS-11), US parameters (tendon appearance and neovascularization), and quality of life (EQ-5D). Safety was also evaluated. Methods. This was a prospective, open-label, multicenter clinical trial. Thirty-five patients (26 in AT group; 9 patients in PT group), who satisfied inclusion and exclusion criteria, were recruited during a 4-month period. Each patient received 1 injection weekly for 3 weeks under US-guidance at the painful site, and was evaluated at 14, 45 and 90 days after the procedure. Subjects were instructed to record on a diary any intakes of the permitted rescue medication for pain relief oral paracetamol, up to the "rescue dose" of 3 g/Day (i.e. 6 tablets/Day) throughout the study period and to interrupt treatment at least 24 hours prior to each visit. Results. Significant improvement occurred in both VISA-A (23.22 +/- 23.17; 95% CI: 13.20; 33.24; p<.0001) and VISA-P (19.25 +/- 11.61; 95% CI: 9.54; 28.96; p=0.0022). NRS-11 score significantly decreased in subjects with AT or PT during the study (p<0.0001 and 1)=0.0040 respectively). Significant improvement of swelling and tenderness evaluated with US in the AT group was revealed (McNemar's test; p=0.0016 and p=0.0114, respectively), while in the PT group the presence of these clinical symptoms showed only a non-significant tendency to decrease (p=0.3173 for both). The EQ-5D-5L total score increased in both the AT and PT groups (mean change vs. baseline at day 90 equal to 15.96 +/- 18.95 (range: -50; 45) and 15.50 +/- 32.42 (range: -40; 71), respectively. Seven patients (20.59%) experienced at least one adverse event (AE), all AEs had mild severity. No serious AE or other significant AE leading to study treatment discontinuation or temporary interruption was reported. Conclusions. Three US-guided HA injections may induce prompt improvement in pain and function in mid-portion Achilles and patellar tendinopathies that last until 90 days of followup. Amelioration in tendon structure, neovascolarization and clinical parameters may also be achieved. The treatment is also safe and well-tolerated.