Tendinopathy is a frequent and ubiquitous disease developing early disorganized collagen fibers with neo-angiogenesis on histology. Peritendinous injection of corticosteroid is the commonly accepted strategy despite the absence of inflammation in tendinopathy. Platelet-rich plasma (PRP) might be a useful strategy to rapidly accelerate healing of the tendinopathy but there is a lack ok knowledge about the amount of PRP to be injected and the opportunity of a second injection in case of partial pain relief. The aim of our study was to assess the potential therapeutic effect of early second PRP intra-tendinous to treat persistent painful tendon tear and tendinosis in a long-term follow-up by ultrasonography (US) and clinical data in case of incomplete efficiency of first PRP treatment injection.

Twenty-four consecutive patients referred for US treatment of tendon tear or tendinosis (T+) were included retrospectively. All had previously received a single intra-tendinous injection of PRP under US guidance (PRPT+) and benefited of a second PRP injection (PRPT2+) under US guidance in order to treat persistent painful. US and clinical data were collected for each anatomic compartment for upper and lower limbs before treatment (D0), 6weeks (W6) after first treatment, 6weeks (W12) after second treatment and until 32-month follow-up. We used Mac Nemar test and regression model to compare US and clinical data.

The residual US size of lesions was not significantly lower at W12 after PRPT2+ as compared to W6 (P=0.86 in upper and P=NS in lower member) independently of age (P=0.22), gender (P=0.97) and kind of tendinopathy (P=NS). Quick dash test values and WOMAC values were not significantly lower in PRPT+ at W12 (average: 21.5months) as compared to W6 (P>0.66) and long-term follow-up (P>0.75) independently of age (P=0.39), gender (P=0.63) and kind of tendinopathy (P=NS). Nevertheless, comparison between D0 and long-term follow-up (LTF) functionnal score was statistically significant (p<0.001 in upper and lower member).

Our study suggests that second early intra-tendinous PRP injection under US guidance does not permit rapid decrease of tendinopathy area in US, nor does it quickly improve clinical pain and functional data in case of incomplete efficiency of first PRP injection. However, in long-term follow-up, patients improved their ability to mobilize pathologic tendons.