Expanded adipose derived mesenchymal stromal cells are effective in treating chronic insertional patellar tendinopathy: clinical and MRI evaluations of a pilot study

Purpose Effect of ultrasound guided injections of autologous ASCs in chronic recalcitrant patellar tendinopathy. Methods Fourteen patients (16 knees, 12/2 males/females) with chronic, recalcitrant (unsuccessfully treated with nonoperative treatments) insertional PT underwent clinical evaluation and magnetic resonance imaging (MRI) before intervention. Stromal vascular fraction cells (SVF) were expanded by in-vitro culture and characterized by flow cytometry. Players were injected with three bi-weekly injections of ASCs followed by physiotherapy. They underwent serial clinical evaluations during a 12-month period with repeated MRI at 6-month post-injection. Results Victorian Institute of sports assessment-patellar tendon questionnaire (VISA-P) scores improved from 43.8 +/- 4.9 at baseline to 58.1 +/- 7.1, 70.3 +/- 7.9 and 78.7 +/- 7.5 at 3, 6, and12months follow-up, respectively. (p = 0.0004 comparing each variable with the previous one). Mean Visual analogue pain in sports (VAS-sport) score during practice significantly decreased from 7.4 +/- 0.5 at baseline to 5.2 +/- 1.5 9 (p = 0.0005), 3.3 +/- 1.1 (p = 0.0004) and 1.5 +/- 0.7 (P = 0.0004) at 3, 6, and 12 months, respectively. Mean Tegner-scores for patients were 8.0 +/- 0.8 before injury and 2.3 +/- 0.9 before treatment, thereafter, improving to 4.8 +/- 0.8 and 7.2 +/- 0.7 at 6- and 12- months, respectively (p = 0.0001). MRI assessed tendon width' did not change over the first 6 months post-intervention. Significant changes were observed for: tendon thickness (12.8 +/- 1.1 to 10.9 +/- 0.7, P = 0.0001); tear length (9.3 +/- 1.3 to 2.3 +/- 0.7, P = 0.0001), tear width (6.3 +/- 0.8 to 3.4 +/- 0.4, P = 0.0001), and tear thickness (4.6 +/- 0.4 to 2.6 +/- 0., P = 0.0001) at baseline and 6 months, respectively. Conclusion Patients with recalcitrant insertional PT showed significant clinical improvement and structural repair at the patellar insertional tendinopathy after injections of autologous ASCs. Results of this study are promising and open a new biological therapeutic modality to treat PT.