Patellar tendinitis (also known as jumper's knee) can cause severe pain in the front of the knee making it difficult for athletes to continue enjoying their sporting activities. Rest, ice and physiotherapy can be successful in many patients. Corticosteroid injections have often been used in patients with more treatment-resistant problems. But in recent years there have been growing concerns over the long-term damaging side effects of corticosteroids on the tendon quality. At the Orthobiologics Clinic we therefore favour PRP injection treatment for patients who have tried and failed non-operative treatment and physiotherapy. The treatment is safe and backed up by several good-quality research publications.
The senior author treated 28 professional and semi-professional athletes with 3 consecutive PRP injections in 1-week intervals. All patients had tried and failed previous non-operative treatment. All injections were carried out under ultrasound guidance and outcome data was collected for up to 2 years. Pain and function improved significantly. 21 athletes returned back to their pre-injury sports within 2-6 months. Follow-up MRI assessment showed improved structural integrity of the tendon at 3 months after the procedure and complete return to normal structural integrity of the tendon in 16 patients (57%). The authors concluded that application of 3 consecutive US-guided PRP injections significantly improved symptoms and function in athletes with chronic PT and allowed fast recovery to their pre-symptom sporting level. The PRP treatment permitted a return to a normal architecture of the tendon as assessed by MRI.
At the Orthobiologics Clinic we were interested to see the benefits of repeat PRP injections in high-level athletes. At the same time, we noticed the limitations in the methodology (case study without randomised control group) and a 25% failure rate with 7 patients changing to lower level sports or undergoing surgery. Despite this, it is still a good outcome for an injection-based treatment without significant side effects or complications.
The authors carried out a systematic literature review with the goal of investigating the functional improvement and pain reduction of different nonsurgical treatments for patellar tendinopathy. They identified 11 trials with 430 patients treated with corticosteroid injections, PRP injections, shockwaves (ESWT), ultrasound, autologous blood injections, dry-needling, topical glyceryl trinitrate and skin-derived tendon-like cells. They found that the treatment most likely to be ranked the best in terms of change in pain score was PRP. In their analysis the authors concluded that LR-PRP has the greatest functional improvement and pain reduction for patellar tendinitis compared with other treatment options. They did however urge caution in overestimating the treatment effect due to the heterogenous nature of the analysed publications.
At the Orthobiologics Clinic we noticed with interest that the authors undertook a very detailed statistical analysis of the available literature. We fully agree with the authors that the methodological quality of many publications is less than ideal and that this can make it difficult to fully ascertain the true value of the various treatments investigated. We do however feel encouraged by the good outcomes of patients treated with PRP.
The authors randomly allocated 33 athletes with chronic patellar tendinitis to injection treatment with either PRP or Hyaluronic Acid. Patients were reviewed 6 weeks and 3 months following treatment. The authors concluded that both PRP and HA can alleviate the symptoms of proximal patellar tendinopathy in the medium term. However, only PRP leads to a decrease in pain associated with an increase in the strength of the quadriceps.
At the Orthobiologics Clinic we were rather disappointed with the very short follow-up of only 3 months. On the other hand, we were pleased to see a randomised trial demonstrating the benefits of both treatments with some advantages of PRP over Hyaluronic Acid.
This systematic literature review analysed the outcomes of non-operative treatment of chronic patellar tendinitis in 70 publications. The authors noticed the poor methodological quality of most studies. The most commonly investigated treatments were eccentric exercise, extracorporeal shockwave therapy (ESWT) and platelet-rich plasma (PRP). Eccentric exercised was most effective in the short-term. But multiple PRP injections provided the best results in the long-term followed by eccentric exercises and ESWT. The authors concluded that the literature documents several nonsurgical approaches for the treatment of chronic patellar tendinopathy with important limitations in terms of study quality. The available evidence showed an overall positive outcome, but some differences have been highlighted. Eccentric exercises may seem the strategy of choice in the short-term, but multiple PRP injections may offer more satisfactory results at long-term follow-up and can be therefore considered a suitable option for the treatment of patellar tendinopathy.
At the Orthobiologics Clinic we feel encouraged by the good long-term outcomes of patients treated with multiple PRP injections.
In this trial 20 patients with chronic patellar tendinitis were treated with a single injection of PRP and followed up for one year. The authors reported that 70% of all patients had a favourable outcome with a significant improvement in pain and function. The authors concluded that a local injection of PRP coupled with a program of eccentric rehabilitation for treating a chronic jumper's knee improves pain symptoms and the functionalities of the subjects' knee up to 1 year after injection.
At the Orthobiologics Clinic we felt encouraged by the good outcomes. The publication also highlights the importance of ongoing physiotherapy as part of the rehab process. However, we felt that the small study group and the absence of a randomised control group make it difficult to comment on the true value of PRP in the treatment of patellar tendinitis.
The authors of this study not only wanted to evaluate the use of PRP in the treatment of patients with chronic patellar tendinitis, they also set themselves the goal of finding out whether and how much any previous treatment may have affected the outcome. 36 patients were investigated, 14 of whom had undergone previous treatment with corticosteroid injections, ethoxysclerol and/or surgery. Both groups showed significant improvements in pain and function. Patients who had undergone previous treatment showed a slightly better improvement.
At the Orthobiologics Clinic we were reassured to see the patients treated with PRP improved regardless of the previous treatment. We were however rather frustrated by the fact that the authors had failed to mention the length of follow-up after the PRP treatment.
The authors of this study investigated whether two injections with PRP work better than just a single injection in patients with chronic patellar tendinitis. 20 athletes received a single injection with PRP while 20 other athletes were treated with two injections. Outcome data was obtained after a minimum of 2 years. The authors found that 78% of patients were successfully treated while 9 patients eventually underwent surgery to treat ongoing symptoms. Those patients who responded well showed a significant improvement in pain and function and this was more pronounced in patients who had received two injections. The authors concluded that two consecutive PRP injections in chronic patellar tendinopathy showed better improvement in outcomes when compared to a single injection.
At the Orthobiologics Clinic we were interested to see that someone had investigated the relevant question of one vs two injections with PRP. While the results of this trial favour two injections, even patients with one PRP injection showed promising outcomes.