Patellar tendinosis (Jumper’s knee) injection

What is Jumper' knee?

What is patellar tendinosis (Jumper’s knee)?

Patellar tendinosis is usually an overuse injury of the patellar tendon. This tendon connects the patella (knee cap) to the upper part of the tibia (the shin bone). It is usually seen in sports involving jumping (like basketball and volleyball) or explosive acceleration (like track athletes, rugby and football). Usually, the pain is better during activity and worse afterwards. When the patellar tendon undergoes regular episodes of high-intensity activity that involves jumping, the increased stress upon the tendon can result in tendon thickening, pain and inflammation. This is referred to as tendinitis or tendinosis.

What are the features of patellar tendinosis?

Pain and tenderness at the front of the knee just beneath the kneecap. The pain usually develops gradually with continuous activity.
The pain is usually aggravated by direct pressure just under the knee cap. It can also be aggravated by activities that involve quadriceps contraction (like squatting and running).
The pain gets better during activity but worsens a few hours later.
There could be local swelling at the site of the pain, below the knee cap.

What other conditions can mimic patellar tendinosis?

Other causes of knee pain that can be mistaken for tendinosis include:

How is patellar tendinosis diagnosed?

Patellar tendinosis is initially suspected on clinical assessment and confirmed with imaging. The patellar tendon is superficial (just underneath the skin surface). Therefore, ultrasound is excellent for assessing the integrity of the tendon and the degree of inflammatory changes. Furthermore, it can guide any intervention. An ultrasound performed by an experienced doctor will provide the following information:

Confirm the diagnosis
Assess the severity of the tendinosis.
Assess for the presence of tears within the tendon.
Assess the size and extent of the tear (whether it’s of high or low grade).
Assess for the involvement of other structures (like the quadriceps tendon and IT band).
Assess for fluid within the knee joint (joint effusion).

Ultrasound is considered the imaging modality of choice for assessing patellar tendon problems. It is superior in demonstrating the internal structure of the tendon when compared to an MRI examination.

Patellar tendinosis vs Patellofemoral joint pain

Patellar tendinosis pain is very local and usually felt by deep palpation (pressing) of the patellar tendon at the front of the knee, particularly at the area just below the knee cap. In comparison, patellofemoral joint pain causes pain at the front of the knee that is usually felt behind the knee cap and, therefore, hard to pinpoint or can be felt as deep pain behind the knee cap.

What are the treatment options for patellar tendinosis?

Patella tendinopathy can be challenging to manage. Treatment usually starts with a specific physiotherapy program involving hip and knee strengthening exercises, particularly slow resistance exercises that are proven effective in managing patellar tendinopathy. Treatment can also include taping, using patellar tendon support during activities and activity modification to allow for patellar tendon healing.

Can injection therapy help in patellar tendinosis?

If the pain is not responding to conservative management (including a dedicated physiotherapy program for at least a 3-month period, injection therapy can be considered. An injection is also considered when the patellar tendinosis is severe, resulting in pain limiting the ability to undergo an effective rehabilitation program, affecting sleep, and interfering with normal daily activities (like walking) or sports activities. The treatment options include ultrasound-guided high-volume saline or platelet-rich plasma (PRP) injections. These treatments should be done under ultrasound guidance. Ultrasound allows for accurate placement of the needle and, thus, delivery of the medicine to the exact site of inflammation. Evidence showed that ultrasound-guided injections result in better pain relief and functional recovery than non-guided injections. Injecting under ultrasound guidance allows for visualising the soft tissues and reduces the risk of injury to the critical structures at the injection site.

Ultrasound-guided high-volume injection

When the patellar tendon becomes inflamed and tendinopathic, the structure of the tendon becomes weakened and compromised. This drives a process called neovascularization. Neovascularisation refers to the formation of new blood vessels in the tendon. These new vessels are usually accompanied by small nerves, and evidence suggests that these might be responsible for some of the pain associated with the condition. Ultrasound-guided high-volume injection aims to eliminate these nerves.

In this procedure, saline (salty sterile water) and a local anaesthetic are used to obliterate these small vessels and nerves, aiming to reduce pain. There is good evidence that the procedure is effective in treating patellar tendinosis. Sometimes, a small dose of corticosteroid (steroid) is added to the injection mixture. Steroids are potent anti-inflammatory medicines added in resistant cases. There are some concerns regarding using steroid injection to treat patellar tendinosis, as there are reports of a small increased risk of tendon rupture. Therefore, we advise using corticosteroid injections only in specific cases. Your specific treatment options will be discussed with you following your ultrasound assessment.

Ultrasound-guided platelets-rich plasma (PRP) injection

PRP injection is a good treatment option for tendinosis in general and is well-used in treating patellar tendinosis. PRP has been clinically proven to enhance the healing process and recovery of tendons, and it has been shown to be a safe treatment option for patellar tendinosis. It is usually reserved for cases that do not respond to all other treatment options. PRP injections involve obtaining a small amount of blood from the patient. Then, the blood is spun at high speeds in a centrifuge machine. This separates the different components of the blood. The PRP is then extracted and injected under guidance into the patellar tendon at the site of inflammation. To learn more, please read our article about Ultrasound-guided platelet-rich plasma (PRP) injection. There is evidence suggesting that a series of three injections a few weeks apart (rather than a single injection) is required to effectively treat the tendinopathy.