Elsevier

Injury

Volume 40, Issue 6, June 2009, Pages 598-603
Injury

Platelet-rich plasma: New clinical application: A pilot study for treatment of jumper's knee

https://doi.org/10.1016/j.injury.2008.11.026Get rights and content

Abstract

This study describes a simple, low-cost, minimally invasive way to apply PRP growth factors to chronic patellar tendinosis; 20 male athletes with a mean history of 20.7 months of pain received treatment, and outcomes were prospectively evaluated at 6 months follow-up. No severe adverse events were observed, and statistically significant improvements in all scores were recorded. The results suggest that this method may be safely used for the treatment of jumper's knee, by aiding the regeneration of tissue which otherwise has low healing potential.

Introduction

Jumper's knee is a troublesome condition of unknown aetiology and pathogenesis, characterised by microscopic ruptures with degenerative changes either in the distal quadriceps tendon or in the patellar tendon. The condition occurs most frequently in the origin of the patellar tendon origin on the inferior pole of the patella.6 It is a common and often chronic problem among athletes, and can severely limit or even end an athletic career.

This disorder affects athletes in many sports, particularly elite athletes engaged in high-impact jumping sports.12 The prevalence of jumper's knee has been estimated to range between 40% and 50% among high-level volleyball players and between 35% and 40% among elite basketball players. There is also a high prevalence among soccer players, sprinters and jumpers.6, 20

Most athletes with this condition are young adults, who have to reduce their training and avoid certain activities, such as excessive jumping.7 An epidemiological evaluation showed that the average duration of pain and reduced function is nearly 3 years.19 A long-term prognostic study recorded that at 15 years follow-up 53% of those being followed reported having to quit their sports career because of their knee problem.18 Thus, it seems that jumper's knee commonly contributes to the decision to abandon an athletic career, and causes mild but long-lasting symptoms that may remain after the athletic career is over.18

Most people with jumper's knee are treated non-operatively; several drugs and physical therapy methods are used to help the healing process. Initial treatments usually include rest, ice, electrotherapy, massage, anti-inflammatory medication or corticosteroid injections. However, there is no evidence-based support for the efficacy of these regimens.11, 23 Recently, eccentric training has been proposed as effective treatment for patellar tendinosis24, 31 but, in difficult cases where results are poor, surgical treatment may be considered and is recommended for athletes whose sports career seems to be in danger. Some studies report good surgical results,15, 25 but the main treatment options are poorly researched, and outcomes after both operative and non-operative treatment may offer incomplete recovery and difficulties in returning to sport.1, 8

In recent years, several studies have described a complex regulation of growth factors for normal tissue structure and reaction to tissue damage, and have shown an important role for growth factor application in the healing of damaged tissue. Platelet-rich plasma (PRP) is a natural concentrate of autologous growth factors, which is now being widely tested in different fields of medicine for its possibilities in aiding the regeneration of tissue with low healing potential; fields of application include orthopaedics, sports medicine, dentistry, dermatology, ophthalmology and plastic, maxillofacial and cosmetic surgery. This method provides a simple, low-cost, minimally invasive way to apply many growth factors to the lesion site. To our knowledge, there are no studies on the clinical application of PRP via multiple injections to favour patellar tendon healing.

The aim of our study was to explore this novel approach to treating chronic patellar tendinosis, by gathering and assessing the number, timing, severity, duration and resolution of related adverse events occurring among study participants before and after treatment. The secondary aim was to analyse the results obtained, to determine feasibility, safety, indications and application of the method for further, wider studies.

Section snippets

Participant selection

Clinical experimentation was approved by the hospital ethics committee and informed consent of all participants was obtained.

The following diagnostic criteria for jumper's knee were used: history (>3 months) of exercise-associated pain, pain or tenderness on palpation, pain during provocative tests of the knee extensors, and findings of ultrasonography or magnetic resonance imaging showing degenerative changes of the tendons. Exclusion criteria included: systemic disorders such as diabetes,

Results

All results are presented as number of tendons treated (not number of individuals).

No complications related to the injections nor any severe adverse events were observed during the treatment or follow-up period. In only one case a marked pain response occurred after the injection and lasted 3 weeks. In all other cases, we recorded moderate pain and stiffness for a few days (Table 1).

A statistically significant improvement in all scores was observed after 6 months (Fig. 3). Statistical analysis

Discussion

Jumper's knee is one of the most common overuse injuries among both male and female athletes; it is an insertional tendinopathy that causes pain and subsequent dysfunction. Jumper's knee is not an inflammatory condition; it occurs because of the high chronic repetitive loading that exceeds the adaptive abilities of the tendon and causes microscopic tears and degeneration in the tendon substance. The poor regenerative ability of tendons, explained by the poor vascularity, oxygenation and

Conclusions

The clinical results of our pilot study are encouraging and suggest that this method may be used for the treatment of jumper's knee. The preliminary short-term results indicate that treatment with PRP injections in the degenerate area has the potential to reduce pain and allow the majority of patients to go back to full tendon-loading activity. However, long-term randomised controlled studies will be needed to confirm the reliability of this procedure, identify indication criteria and improve

Acknowledgments

We thank the following for their assistance: S. Zaffagnini, S. Bassini, F. Pieretti, A. Gabriele, M. Vaccari, A.M. Del Vento, M. Zagarella, V. Roverini, I. Brognara, L. D’Amato, S. Ardone, Elettra Pignotti, Keith Smith.

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