Epicondylar tendinosis is frequent in athletes who perform repetitive wrist motions and strong gripping. PRP has advantages in the treatment of tennis elbow as demonstrated for the first time by Mishra and Pavelko in 2006. In this cohort study, the authors reported a clinical decrease of pain after PRP treatment in 15 patients having severe chronic tendinopathy of the elbow. The test group was compared to a control group of five patients receiving local anesthesia only. The patients were observed for 24 months. After 8 weeks of treatment, they noticed a 60 % improvement in pain scores for patients treated with PRP compared to 16 % improvement in control patients. At final follow-up, the PRP group reported 93 % reduction in pain. Although this study lacked a complete randomization and presented a reduced number of patients, the long follow-up and the absence of complications showed an excellent safety profile for PRP as a potential treatment option for sports-related injuries [5]. Perbooms et al. performed a double-blind randomized controlled trial of 100 patients undergoing lateral epicondylitis treatment with PRP (51 patients) or with corticosteroid (49 patients). They observed that a single injection of PRP significantly reduced pain (visual analog scale (VAS) score) and improved function (Disabilities of the Arm, Shoulder and Hand (DASH) score) at 6 months and 1 year follow-up better than corticosteroid treatment and without any complications [6]. Creaney and colleagues most recently published results of a prospective single-blind randomized trial on the efficacy of two types of blood injections. A group of 150 patients with elbow symptoms resistant to conventional treatment received either PRP injections or autologous conditioned plasma. The injections were repeated twice and both groups were compared. Unfortunately, there was no placebo control group. In both groups, they reported marked reduction in pain and increase in function but without any significant difference between groups after 6 months of follow-up [7].

Overuse injury of the Achilles tendon is a frequent problem that often affects sportsmen but also sedentary middle-aged individuals. Patients with Achilles tendinopathy who have failed physical therapy and multiple modalities of conservative treatment are candidates for PRP injections.

DeVos and colleagues were the first to use the PRP in the treatment of the Achilles tendon. In this randomized controlled double-blind study, 54 patients with mid-portion Achilles tendinosis were randomized to receive either injection with PRP or with saline associated with eccentric gymnastic exercises. As a result of the treatment, pain decreased, and functional scores, such as Victorian Institute of Sport Assessment-Achilles questionnaire (VISA-A), improved significantly in both groups. Even if results in the PRP group were somewhat higher, no statistical significance was found after 6 months between the two groups. There was also no difference in patient satisfaction or in the time taken to return to sport. Importantly, no relevant side effects were identified [8]. The same investigators subsequently extended the follow-up to 1 year, without finding any supplementary PRP benefit. Localized bleeding caused by the injecting syringe might have triggered the tissue healing process. A positive response could also be due to a placebo effect, as invasive procedures lead to higher expectancy of good results. Finally, in both groups, ultrasound showed that tendon structure and neovascularization improved significantly, without any group differences after 6 and 12 months. One of the main reasons for the absence of group differences is certainly the fact that standardized eccentric exercise training has already been shown to improve actual tendon structure [9]. Monto et al. treated 30 patients with Achilles tendinopathy who had failed 8 months of conservative treatment and physical therapy. The treatment involved the injection of PRP under ultrasound guidance. The pretreatment American Orthopaedic Foot and Ankle Society (AOFAS) score averaged 34, indicating significant pathology. AOFAS score increased from an average of 34 to 92 after 6 months of treatment. Ninety-three percent of patients were fully satisfied [10]. Gaweda and colleagues conducted a prospective case series on the efficacy of use of PRP injections in the treatment of a non-insertional Achilles tendinopathy. The authors showed that a single injection of PRP, under ultrasound guidance, determined a significant improvement of AOFAS and VISA-A scores in 14 patients (15 Achilles tendons) for up to 18 months [11]. Sanchez et al. showed a shorter time in the recovery of motion and return to sporting activities in athletes undergoing Achilles tendon surgical repair with augmentation of PRP than the control group. Controls were treated with an identical surgical procedure performed by the same surgeon, but they did not receive PRP during surgery. A fibrin scaffold was used in addition to PRP. The authors observed no wound complication and a faster return to jogging and training activities [12].

Jumper’s knee (patellar tendinopathy) is common in athletes of sport disciplines where jumping is frequent, e.g., basketball, soccer, and volleyball. This pathology is characterized by angiofibroblastic hyperplastic changes within the substance of the tendon, which is typically located at the bone–tendon junction of the inferior pole of the patella.

Volpi and colleagues were the first to introduce a PRP injection to accelerate healing in chronic patellar tendinopathy of eight professional athletes. Participants, recalcitrant to conservative measures, received a single injection of PRP and were observed for 4 months, but only seven patients received a follow-up examination. The authors found a significant improvement of the VISA scores after the infiltration of PRP under ultrasound guidance. Furthermore, the nuclear magnetic resonance imaging (MRI) showed a reduction of irregularities in the tendon [13]. In a recent report, Kon et al. reported similar results in a case series for the treatment of 20 patients who experienced recurrent patellar tendinopathy symptoms, over a 20-month period. Participants received three PRP injections within 1 month, showing statistically significant improvement in pain and physical function at 6 months follow-up [14]. Filardo et al. had good results with the use of PRP (type 1) for chronic patellar tendinopathy in 15 athletes [15]. Recently, a prospective study evaluated the influence of previous treatments on the effectiveness of PRP injections in 36 patients with chronic patellar tendinopathy. Assessment was done before and after injection of PRP using the Victorian Institute of Sport Assessment for patellar tendinopathy (VISA-P) questionnaire and VAS score. The first group (14 patients) had been treated with cortisone, ethoxysclerol, and/or surgical treatment before the injection, while the second group (22 subjects) had not received such treatments. A statistically significant improvement in both groups at 18 months was found but larger in the group without previous treatments. Thus, this study opens the question about a relationship between prior treatment and efficacy of PRP injections [16].