Anatomy of the patella tendon

The patella tendon is located between the bottom of your patella (kneecap) and the top of your tibia (long bone of the shin). The patella tendon is a continuation of the quadriceps tendon that is located just above the patella. It attaches to the large muscles at the front of your thigh called the quadriceps muscle (see the below image).

The quadriceps muscles, quadriceps tendon, patella and patellar tendon are responsible for extending (straightening) your knee during running and jumping and are collectively known as the knee extensor mechanism.

What is patella tendinopathy?

Tendinopathy is believed to be accountable for a significant proportion of all musculoskeletal pathology resulting in referral to a health professional (Resteghini et al., 2016).

Patella tendinopathy, commonly known as jumper’s knee, is predominantly an overuse injury. The patellar tendon is subjected to high levels of stress via the action of the knee extensor mechanism. It is a common site for pain and injury to occur, especially among the sporting population. Research has shown patella tendinopathy to be present in up to 14-16% of all athletes who play sports requiring jumping, such as volleyball and basketball (Cong et al., 2016).

When the patellar tendon is subjected to regular episodes of high intensity activity, often involving jumping, the tendon can become inflamed and painful. An inflamed and painful tendon is known as tendinitis. If the patellar tendon is repeatedly exposed to further episodes of tendinitis the tendon is unable to recover fully resulting in an incomplete, sub-optimal healing response. The result of incomplete tendon healing is a pathologically weak and thickened tendon. A weak and thickened tendon is known as a tendinopathy. A pathologically weak tendon can cause significant pain and disability and in severe cases can result in tears (Cong et al., 2016).

Jumper’s knee refers to tendinopathy at three specific locations within the knee extensor mechanism (Dan et al., 2018).

Dan et al. (2018) describe the following tendon pathologies (see below image) as associated with Jumper’s knee:

  • Insertional quadriceps tendinopathy – the quadriceps tendon attaches to the uppermost aspect of the patella.  Insertional quadriceps tendinopathy has been reported in 25% of all jumper’s knee cases.
  • Proximal patella tendinopathy (also known as inferior pole tendinopathy)  – the patella tendon originates from the bottom of the patella at a point known as the ‘inferior pole’. Proximal patella tendinopathy has been documented to account for 65% of all jumper’s knee pain. It is by far the most common cause we see at Complete.
  • Distal patella tendinopathy (also known as tibial tubercle tendinopathy) – the patellar tendon inserts in a small bony prominence at the top of the tibia called the tibial tubercle, and this region is responsible for approximately 10% of all jumper’s knee cases.

This rest of this article focusses on the most common condition of the three; proximal patella tendinopathy.

Common risk factors associated with the onset of tendinopathy include:

  • Sport involving repetitive, high intensity, knee extension such as running, squatting, climbing and jumping
  • Age – tendinopathy is most commonly seen later on in life
  • Sex – patella tendinopathy is most commonly seen in men
  • Muscular imbalances can occur due to muscle weakness or tightness. This can change the biomechanics around the knee, resulting in patella tendon overload and tendinopathy.
  • Inadequate preparation for sport – if you have not prepared your tendon for the increased demands required during sport it can be susceptible to injury. Sport specific strength training and an effective warm up is essential to prevent tendinopathy.
  • Sudden changes in activity levels such as starting a new sport and increasing frequency or intensity of your exercise too quickly.
  • Tendinopathy has also associated with increased weight (high body mass index (BMI)), high cholesterol, diabetes and other metabolic conditions.

How do we know if you have patella tendinopathy?

Symptoms of often present gradually, without trauma, and can take many months of repetitive overloading of the tendon before becoming problematic.

Symptoms of patella tendinopathy include:

  • Pain located just below the knee cap
  • Pain which is made worse with increased levels of activity such as walking, running or jumping.
  • Pain is often worse after activity
  • Pain after prolonged periods of rest such as when rising from sitting at your desk or from getting out of bed in the morning.
  • Pain with negotiating stairs and inclines.
  • Morning stiffness – your knee may feel stiff first thing in the morning. Stiffness typically wears off within an hour.

How is patella tendinopathy diagnosed?

Obtaining an accurate diagnosis of jumper’s knee is essential. It allows the clinician to select the most effective treatment plan for you. A diagnosis will be made by your clinician by carrying out a comprehensive clinical assessment and a diagnostic ultrasound scan.

Clinical assessment regularly includes the following:

  • An in-depth clinical interview – your clinician will ask you a series of questions which will help formulate a hypothesis as to why you have your pain. Questions such as why your pain started, how long you have had your pain, what aggravates your symptoms and what eases your symptoms will be asked. A full medical history will also be documented. This is to uncover any possible medical conditions that could be causing your pain such as systemic inflammation arising from rheumatoid arthritis.
  • Physical assessment – your clinician will assess your knee using a series of tests including joint range of movement, muscle flexibility and strength, and palpation of different structures surrounding the knee. Your clinician will also ask you to perform a set of simple functional tasks often including single leg balance and single leg squatting, lunging and jumping. They may also analyse your walking and running style.

The clinical assessment is normally sufficient to diagnose a patella tendinopathy. However, a clinical assessment is limited in providing any further information about the tendon structure and surrounding tissues. This is very important especially of your symptoms are not improving.

Diagnostic musculoskeletal ultrasound imaging

A diagnostic ultrasound scan is carried out on your first session to gain more information. A scan will be able to answer the following questions:

  1. How severe is the tendinopathy ?
  2. Is there a tear in the tendon?
  3. Is there inflammation of the surrounding bursa?
  4. Is there inflammation of the fat pad?
  5. Is there involvement of other structures such as the meniscus (cartilage in the knee)

Diagnostic ultrasound scan is able to assess tendon structure and inflammation associated with tendinopathy. Ultrasound is regarded as the gold standard imaging technique for assessing tendon structure and pathology (Dan et al., 2018). It shows the internal structure of the tendon better than on an MRI scan.

Complete Injections clinicians are all highly experienced physiotherapists and musculoskeletal sonographers. During your initial assessment, you will be provided with a formal diagnosis using a combination of clinical examination and diagnostic imaging after which the clinician will be able to prescribe the most appropriate treatment for your condition.

How do we treat patella tendinopathy knee?

Patella tendinopathy is notoriously challenging to rehabilitate and therefore it is essential that treatment starts as early as possible (Cong et al., 2016). Rehabilitation of jumper’s knee requires specialist physiotherapy intervention involving any number of the following techniques:

  • Advice on activity modification allowing the patellar tendon to rest and heal appropriately.
  • Hip and knee strengthening exercises. Research has shown that heavy slow resistance (HSR) exercises can have a positive effect on patellar tendinopathy (Kongsgaard et al, 2009).
  • Biomechanical re-education – this may involve teaching you how to correctly squat, run or jump.
  • In some cases, your clinician may perform soft tissue manipulation techniques or acupuncture to help reduce any pain that might be making your rehabilitation exercises difficult to perform.
  • Advice on taping or using a patellar tendon support during sport.

Research shows that a rehabilitation programme for patella tendinopathy should be carried out for 3 months before considering further intervention such as injections or shockwave therapy.

What if physiotherapy does not work?

Physiotherapy will always be the pillar of your treatment, but there are other options alongside physiotherapy to assist your progress along if required:

Extracorporeal shockwave therapy (ESWT)

Shockwave therapy produces a series of powerful sound waves which provide a small dose of controlled microtrauma to the patella tendon. Research has shown that shockwave stimulates the tendons natural healing process, initiating a new healing process. Local nerve endings surrounding the painful tendon become desensitised by these pulses, resulting in pain and symptom reduction.

Recent evidence suggests positive outcomes following 3-5 shockwave treatment sessions running concurrently with a progressive loading exercise program for the treatment of all lower limb tendinopathies (Zwerver et al, 2010).  All clinicians at Complete are trained to deliver shockwave. If you would like more information regarding shockwave therapy please contact us on 0207 4823875 or email injections@complete-physio.co.uk.

Injection therapy

If your pain has persisted for over 3 months and you have not improved with physiotherapy then you may be appropriate for injection therapy. Injection therapy has historically been used within musculoskeletal medicine to reduce pain and inflammation allowing you to effectively rehabilitate your condition.

It is of particular value in the following circumstances:

  • Your pain is affecting your ability to sleep or is waking you during the night.
  • Your pain is significantly limiting your ability to perform normal activities of daily living or partake in sports or leisure activities.
  • Your pain is affecting your ability to undertake your rehabilitation exercises.
  • Your pain is getting worse or your progress has plateaued.
  • You have embarked on a 3 month rehabilitation programme with little or no improvement

There are two injection options for patella tendinopathy.

1. Ultrasound-guided high-volume injection

When the patellar tendon becomes tendinopathic, the internal structure of the tendon becomes compromised. Tendinopathic change drives a process called neovascularisation. Neovascularisation is the growth of new blood vessels within and around the tendon. These new vessels are accompanied by very small nerves. It is hypothesised that these small nerves are responsible for some of the pain associated with patella tendinopathy.

An ultrasound-guided high-volume injection uses a combination of saline (sterile water) and a local anaesthetic to obliterate these small vessels and nerves and reduce pain. This technique has been practised for over 10 years and has some evidence to support its use (Barker-Davies et al, 2017). On occasion a small dose of corticosteroid (also known as steroid) may be added to the injection. Steroid is a potent anti-inflammatory and is reserved for very irritable and inflamed cases.

Current research has raised concerns surrounding steroid injection for treating patellar tendinopathy. This is due to a small increased risk of tendon rupture following the procedure and therefore, corticosteroid injection should be used judiciously (Resteghini et al., 2016). The use of steroid in your specific case will be discussed following your assessment and ultrasound scan.

2. Ultrasound-guided platelet rich plasma (PRP) injection

PRP has been clinically proven to enrich the healing process and speed recovery of tendons. It has been shown to be a safe treatment for patellar tendinopathy. Although there is evidence to support its use in patella tendinopathy, the evidence to supports its use is minimal and there is conflicting evidence. It is reserved for cases that have failed to respond to all other treatment options (Cong et al., 2016).

PRP requires a small amount of blood to be extracted from a vein in your arm. Blood is then spun, at high speeds, in a centrifuge machine.  This separates the PRP from other blood molecules. PRP is then injected, under guidance, in and around the patellar tendon. Research has suggested a series of three injections is required to successfully treat tendinopathic pain.

Using ultrasound guidance is essential to ensure the accuracy of the injection and limit any potential side effect. Ultrasound guided injections are better tolerated by patients with less procedural pain. At Complete, to ensure you experience the maximum benefit with the least discomfort, all injection techniques are performed using ultrasound guidance.

Complete Injections offers a same day service on all guided injections. All clinicians are independent prescribers, musculoskeletal sonographers and injection therapists. You are able to self-refer directly into our service, you do not need to be referred by your G.P.  If you would like more information or would like to book an appointment please contact us on 0207 4823875 or email injections@complete-physio.co.uk.

References:

Barker-Davies, R.M., Nicol, A., McCurdie, I., Watson, J., Baker, P., Wheeler, P., Fong, D., Lewis, M. and Bennett, A.N., 2017. Study protocol: a double blind randomised control trial of high volume image guided injections in Achilles and patellar tendinopathy in a young active population. BMC musculoskeletal disorders, 18(1), p.204.

Cong, G.T., Carballo, C., Camp, C.L., Album, Z., Lebaschi, A., Zong, J. and Rodeo, S.A., 2016. Platelet-Rich Plasma in Treating Patellar Tendinopathy. Operative Techniques in Orthopaedics, 26(2), pp.110-116.

Dan, M., Parr, W., Broe, D., Cross, M. and Walsh, W.R., 2018. Biomechanics of the knee extensor mechanism and its relationship to patella tendinopathy: A review. Journal of Orthopaedic Research®, 36(12), pp.3105-3112.

Kongsgaard, M., Kovanen, V., Aagaard, P., Doessing, S., Hansen, P., Laursen, A.H., Kaldau, N.C., Kjaer, M. and Magnusson, S.P., 2009. Corticosteroid injections, eccentric decline squat training and heavy slow resistance training in patellar tendinopathy. 

Resteghini, P., Khanbhai, T.A., Mughal, S. and Sivardeen, Z., 2016. Double-blind randomized controlled trial: injection of autologous blood in the treatment of chronic patella tendinopathy—a pilot study. Clinical Journal of Sport Medicine, 26(1), pp.17-23.

Wiley, J.P., 2013. The Effectiveness of Injection Treatments for Patella Tendinopathy: A Review. Clinical Journal of Sport Medicine, 23(2), pp.121-122.

Zwerver, J., Verhagen, E., Hartgens, F., van den Akker-Scheek, I. and Diercks, R.L., 2010. The TOPGAME-study: effectiveness of extracorporeal shockwave therapy in jumping athletes with patellar tendinopathy. Design of a randomised controlled trial. BMC mu