Tendinopathy is characterized by micro-tears of collagen fibers due to repetitive overuse and scarring. Once tendinopathy occurs, it adversely affects function and increases the risk of re-injury. Furthermore, because of their poor vascularization, tendons have poor healing properties and heal more slowly compared to other connective tissues (Fenwick et al., 2002; Hayem, 2001). The major histologic characteristic of chronic tendinopathy is not inflammation but rather angiofibroblastic degeneration (Edwards and Calandruccio, 2003; Mishra and Pavelko, 2006). Therefore, new treatment options including dry needling, prolotherapy, and extracorporeal shockwave therapy are used to embrace inflammation rather than suppress it (Sampson et al., 2008).
Platelet-rich plasma (PRP) is a fraction of autologous blood that has a platelet concentration above the autologous blood from which it was derived. PRP aids healing in response to musculoskeletal trauma (Foster et al., 2009). PRP contains high levels of growth factors, which play important roles in tissue healing; these factors include transforming growth factor-p1, insulin-like growth factors 1 and 2, vascular endothelial growth factor, basic fibroblast growth factor, and hepatocyte growth factor (Alsousou et al., 2009; Molloy et al., 2003). Growth factors influence the cellular processes for tissue repair, facilitate healing by activating intracellular signal pathways via binding growth factor receptor, and play important roles in revascularization (Tabata, 2004).
PRP is obtained by sequestering and concentrating platelets using gradient density centrifugation (Marx et al., 1998). As a concentrated source of autologous platelets, PRP contains several different platelet-derived growth factors and other cytokines that promote soft tissue and bone healing. Autologous PRP was first used in the field of oral and maxillofacial surgery (Anitua, 1999; Marx et al., 1998) and has also been widely used in the other fields (Everts et al., 2007; 2008; Radice et al., 2010; Sampson et al., 2008). Injection is the preferred method to administer PRP into the injured tendon and various injectable PRP preparations are available for the management of various tendinopathies. PRP injection is increasingly being used as a regenerative therapy to treat tendinopathies. PRP can be used in the treatment of chronic nonhealing tendon injuries, including the lateral and medial epicondylar, patellar, and Achilles tendons, among others. Several studies demonstrate PRP injection has beneficial effect on tendinopathy of elbow (Gosens et al., 2011; Mishra and Pavelko, 2006; Nguyen et al., 2011; Peerbooms et al., 2010). However, its effectiveness remains controversial, because only a few high-quality randomized controlled trials have evaluated PRP for the treatment of tendinopathy of elbow (Krogh et al., 2013).
Ultrasound-guided injection makes more sophisticated delivery possible by enabling the visualization of the injected products in the region of tendon injury (Loftus et al., 2012). Because the core premise of PRP is to increase the concentrations of active cellular components at the injury site, it is important to determine how much of the delivered PRP actually stays at the injection site and how much is distributed into the surrounding tissues. However, there are only a few reports about the post-injection distribution of PRP products (de Vos et al., 2010; Loftus et al., 2012).
Characteristics of the spreads of platelet-rich plasma (PRP) are not widely known despite commonly use. This study aims to evaluate whether PRP stays within the injected area by using ultrasonography, to improve understanding of the spreads of intratendinous injected PRP.
Patients with elbow pain who had visited the outpatient clinic of a university hospital between June 2013 and February 2015.
Inclusion criteria were as followed, (1) more than 6 months of elbow pain; (2) pain score of the affected elbow greater than 4 on the visual analog scale (from 010); (3) diagnosis of tendinopathies of elbow; and (4) no or little response to conservative care for at least 3 months. The exclusion criteria were as followed: (1) presence of another diagnosis of elbow, such as fracture, rheumatologic or neurologic diseases; (2) any prior surgery of the elbow region; (3) history of any injections on affected elbows, such as steroid or prolotherapy, within 3 months prior to visit; (4) unstable medical condition or known uncontrolled systemic diseases. This study was approved by the hospital's institutional review board, and written informed consent was obtained from all participants after they were briefed about the study's purpose and examination procedures.
A physiatrist with 11 years of musculoskeletal ultrasonography experience performed ultrasound-guided PRP injection and ultrasonographic examinations of the affected elbow before and after the procedure. All examinations were performed using an Antares ultrasound scanner (Siemens, Berlin, Germany) with a 5-13-MHz...