What is the patellar tendon?
The patellar tendon is the extension of the quadriceps tendon, which is a continuation from the patellar to the tibial tubercle. The tendon which, is sometimes referred to as the patellar ligament as it attaches bone to bone, is about 5 cm long. The tendon originates from the inferior pole of the patellar on its apex and from a rough attachment point on the posterior surface. Some of the more superficial fibres are continuous from the quadriceps tendon over the top of the patellar. The medial and lateral patellar retenaculum are fibres on the medial and lateral expansions of the quadriceps tendon, which terminate by inserting into the capsule of the knee, running either side of the patellar.
The function of the patellar tendon is to transmit force from the quadriceps muscle group into the tibia. The patellar tendon is a necessary part of the whole extensor mechanism of the knee.
Although the patellar tendon is comprised of dense collagenous tissue the tendon is reported to go through a deformational change in all 3 axes during knee flexion. During knee flexion the length of the patellar tendon increased sharply as the knee progressed through flexion from full extension to 30 degrees. This helps during deeper ranges of motion, as the force transmission is not subject to elastic deformation in the patellar tendon. After this point of flexion the length of the tendon remains the same. The tendon is reported to elongate by 6.6%. This is significant for post surgical intervention, as rehab protocols need to keep below 30 degrees during the early stages to avoid excessive loading of the tendon/quadriceps mechanism.
The sagittal plane kinematics are interesting as there is a change from an anterior pull on the tibia in low flexion angles to a posterior pull on the tibia at much high flexion angles (between 60-90 degrees of flexion). In the coronal plane the patellar tendon is oriented more medially upto 30 degrees of flexion. This results in a medial tibial rotation during quadriceps contraction, which is not seen in greater ranges of flexion due to a smaller coronal plane angle with the tibial long axis.
What is Patellar tendonitis?
Patellar tendinopathy is a very common condition affecting the general population as well as athletic populations. The prevalence in some sports such as volleyball can be as high as 50%. People who partake in other jumping and landing sports are also a the same increased risk factor as volleyball players. The condition has many different names;
- Jumpers Knee
- Patellar Tendonitis
- Enthesitis of the patellar tendon
- Patellar tendinosis
Initially the condition was described as an inflammatory condition but through a more detailed understanding of the histopathological changes in the tendon and the lack of inflammatory cells, the condition is now regarded as a tendinopathy (largely degenerative).
The most commonly affected area within the tendon, which spans a large distance, is the inferior pole of the patellar. However, palpation of the region is a little hit and miss with regards to diagnosis of the condition, although a recent 2009 article (Ramos et al) suggest that the palpation has a high sensitivity and low specificity for diagnosis of patellar tendinopathy in young athletes. Jumping, ascending, descending stairs and long periods of knee flexion can make it significantly worse along with explosive physical activities.
There are several risk factors, which predispose to patellar tendinopathy. Highly intense or explosive physical activity with or without increased jumping will increase the occurrence of patellar tendinopathy. Sudden increases in the intensity of physical activity such as being on a break from sport and going back to it, or taking it up quickly causes damage to the patellar tendon and results patellar tendinopathy.
Muscular imbalances in the leg muscles harbour latent issues with regards to improper loading cycles in the tendon. This can result in overload or under loading of the tendon, which also results in patellar tendinopathy/tendinitis.
Over-developed or tight leg muscles lead to increased mechanical load on the patellar tendon, resulting in overuse of the collagenous material within the tendon.
What other treatments are available for Patellar tendonitis?
The main types of treatment for patellar tendinopathy vary somewhat in the scale of research backing each one up;
- R.I.C.E applied in the early stages is normally a first line conservative treatment,
- Exercises to correct muscle imbalances
- Exercises and stretches to correct muscle tightness
- Platelet Rich Plasma (PRP) Injections
- Eccentric loading programmes
- High Volume Saline injection
- Shockwave therapy
- Surgery is often a last resort to help remove any degenerative tissue within the tendon
How is shockwave therapy applied in patellar tendinopathy?
Shockwave therapy for Patellar tendonitis is applied following a set protocol. The clinician will carry out a thorough case history taking which isolates the area that is painful and begins to understand the clinical history behind the condition. It is important to make sure that the condition being treated is actually a Patellar tendonitis and is therefore treatable with shockwave therapy.
During the examination period a tender point where the pain is maximal will be located, upon which a water-based medium will be applied. This aids the transmission of the impulses into the desired area.
The probe will then be placed over the desired area and then treatment for your Patellar tendonitis will begin. At first the clinician will ensure the discomfort is kept to a minimum. After a while as the impulses increase little pain is felt. Although, more often than not there is some pain felt over the area of application. After treatment you should feel very little pain and this may last for a few days. After then an aching sensation can occur. After subsequent treatments there will be a definite improvement in symptoms leading to reduction in the original pain felt.
How long will shockwave therapy take to work?
Generally most applications of shockwave for Patellar tendonitis and most conditions will resolve within 3-4 sessions of 30 minutes (roughly). This obviously can depend on the exact presentation of the condition. Making sure you see someone quickly to have the condition diagnosed can reduce the number of sessions needed.
It is vital that you continue to work with a physical therapist to maintain the exercise regime you should already be carrying out for Patellar tendonitis, prior to consulting for shockwave treatment. This will involve balancing exercises, strength exercises and a good eccentric loading programme depending on your stage of Patellar tendonitis.
What is the evidence for shockwave therapy and this condition?
Wang et al (2007) studied the effects of shockwave therapy on chronic patellar tendinopathy. At the 2- to 3-year follow-up, the overall results for the study group were 43% excellent, 47% good, 10% fair, and none poor. For the control group, the results were none excellent, 50% good, 25% fair, and 25% poor. The mean Victorian Institute of Sports Assessment scores were 42.57 ± 10.22 and 39.25 ± 10.85, respectively, before treatment (P = .129) and 92.0 ± 10.17 and 41.04 ± 10.96, respectively, after treatment (P < .001). Satisfactory results were observed in 90% of the study group versus 50% of the control group (P < .001). Recurrence of symptoms occurred in 13% of the study group and 50% of the control group (P = .014). Ultrasonographic examination showed a significant increase in the vascularity of the patellar tendon and a trend of reduction in the patellar tendon thickness after shockwave treatment compared with conservative treatments.
Peers et al (2003) showed efficacy of the ESWT on patellar tendinopathy in 15/28 knee cases which were all treated with Shockwave therapy. The 13 unsuccessful cases were not treated.
All in all there are around 7 articles all published after 2000, which included some 215 cases of patellar tendinopathy treated by ESWT. Although, some of the studies lacked in methodological areas (under powered and not much of a follow up) the studies produced very positive results in favour of the use of shockwave therapy for patellar tendinopathy. The variation in methodology and the consistency in outcomes make it difficult to ascertain the best treatment regime for using ESWT on this condition.
Where can I get shockwave therapy for patellar tendinopathy?
One is able to get shockwave therapy at a few specialist clinics in the UK. There are a growing number of clinics providing this specialist form of treatment. It is beneficial to make certain the type of machine they use is a swiss dolor clast machine as this is the only one that has been tested to high level in research papers.
At Perfect Balance Clinic we often see people with different types of Tendinopathy who have tried other forms of treatment. Shockwave for us has been the one form of treatment that has consistently delivered results for Tendinopathy.
How long will the treatment last for?
If everything goes to plan with your shockwave therapy for Patellar tendonitis then the treatment should make a significant contribution to reducing the pain and improving the function of your Patellar tendonitis. In most cases the shockwave will get rid of the patellar tendinitis.
With some tendon surgery there is a 75% success rate at 18 months, with shockwave for the same condition it has been shown that up to 80% of patients who have received the shockwave therapy at 18 months have a good to excellent result. Shockwave is better than surgery for certain tendinopathy and more research is being done with this in mind.
Shockwave therapy is a safe and effective form of treatment in the management of patellar tendinopathy. The results of which are considerably better than the conservative measures which we currently use to manage patellar tendinopathy.
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