Running and jumping over and over often leads to a condition in athletes known as patellar tendinosis or jumper’s knee. Pain along the front of the knee during the activity that goes away with rest is a cardinal symptom of this condition. Dancers, gymnasts, and basketball, soccer, and volleyball players are affected most often.
What can be done about his problem? Jumper’s knee goes away when the muscles along the front of the knee (extensor mechanism) that pull across the patella (kneecap) stop pulling. It is a self-limiting, self-resolving condition. Therefore, the first recommended treatment is always to stop overloading the extensor mechanism. Rest, anti-inflammatory medications, and specific exercises under the supervision of a physical therapist are advised.
But many athletes work through the pain until conservative (nonoperative care as described above) is no longer successful in reducing pain. At that point other treatment options are considered. In this study, sports medicine experts compared two additional treatment approaches for chronic tendinopathy of the extensor mechanism: 1) platelet-rich plasma (blood injection therapy) and 2) extracorporeal shock wave therapy (ESWT).
Platelet-rich plasma (PRP) refers to a sample of serum (blood) plasma that has four (up to 10) times more than the normal amount of platelets and growth factors. This treatment enhances the body’s natural ability to heal itself and is used to improve healing and shorten recovery time from acute and chronic soft tissue injuries. The group of athletes in this study who received PRP were given two injections over a two week period.
Extracorporeal shock wave therapy (ESWT) is a way to generate sound waves outside the body that can be focused at a specific site within the body (in this case, the knee). This treatment technique is also referred to as pressure or sound wave therapy. It is a noninvasive, outpatient procedure.
Pressure waves travel through fluid and soft tissue to sites where there is a change in tissue density. A common interface is where the soft tissues meet bone. A special device delivers shockwaves to the target point where treatment is needed. The shockwaves break down scar tissue that has built up. The body’s repair mechanisms are stimulated to promote healing. New blood vessels develop in the injured area to help jump start the healing process. Three sessions of ESWT were delivered to the second group in this study in 48- to 72-hour intervals.
In order to measure and compare results between the two groups, they used three tools: 1) the Victorian Institute Sports Assessment-Patella questionnaire, 2) the pain visual analog scale, and 3) a modified version of the Blazina scale. The athletes completed each questionnaire before treatment and again after treatment at two, six, and 12 months post-treatment. Information gained from these surveys included: severity of pain, level of function, and ability to participate in sport(s).
In comparing the two groups responses to treatment, they found everyone in both groups had significant improvements throughout the follow-up time period. At the end of two months, there was no real difference between the two groups. But later (at the six-month and one-year recheck), the platelet-rich plasma (PRP) injection group pulled ahead with significantly better improvement. Significantly more athletes in the PRP group (compared with the shock therapy group) were also able to return to full sports participation (at a level equal to before their injury).
This may be the first randomized, controlled trial comparing treatment results between these two approaches in athletes with jumper’s knee. Both treatments focus on the failed healing of the overused tendon by promoting cell growth, release of growth factors, and improving tissue remodeling. As this study showed, both are effective in the short term but platelet-rich plasma may have better mid-term results. Further study is needed to assess long-term results.