Patella Tendinopathy (Runner's Knee)

Patella Tendinopathy (PT) is a chronic condition of the knee and is often seen in both general and athletic populations (9). PT is characterized by pain and dysfunction at the anterior knee (front), specifically at the inferior pole of the patella tendon and where it attaches to the tibia (8). This can either be felt as an occasional sharp stabbing pain or a dull ache below the patella (kneecap) and pain can be felt doing certain activities such as crouching down, prolonged sitting, stairs or kneeling (6). The type of pain felt can usually be attributed to the duration of time an individual has had the complaint for, the more chronic the injury the worse the pain may get (13). You may also find that when the tendon is loaded you get an immediate intense pain, but when load is removed this pain will subside just as quickly (8). Unfortunately, these types of repetitive strain injuries are difficult to identify especially when symptoms are mild, which is why many athletes continue to train through discomfort (13). 

Overuse to the patella tendon can be caused through recurrent high impact ballistic loading to the knee extensors (quadriceps muscles) (14). With this repetitive loading microtrauma can occur, especially when the individual is exposed to extreme forces such as rapid acceleration, deceleration, jumping and landing exercises (14). Sports that are susceptible to this type of injury are running, football, volleyball, weightlifting and basketball due to the repetitive nature of the activity (14). 

When and how you get the pain may indicate the phase of tendinopathy you are experiencing. This may help us as clinicians to identify the integrity of the tendon and how to best manage your complaint. One of the ways we can do this is by using tools such as the  Blazina jumper’s knee scale and the Kennedy tendinopathy stages (14).

A better understanding of what happens to the tendon that causes us the pain at the front of the knee, will allow us to identify the best strategies for your rehabilitation and recovery. 

The Science part of a tendinopathy: 

There are three main phases that a tendon goes through to become a chronic injury and this is called the tendinopathy continuum (1). These are detailed below (1):

Reactive tendinopathy – This is the first phase when you may start to experience discomfort from your activity. The tendon responds to the load applied upon it, usually due to a rapid increase in load or can be from direct trauma (landing directly onto the kneecap). We used to think that this was an inflammatory process however, although sometimes swelling and heat can be felt it is now understood that in this phase the tendon remains intact. This means there is minimal change in the integrity of the tendon and more importantly, a reversable process!

Tendon Disrepair – This process starts if a reactive tendinopathy has been ignored and the tendon continues to be excessively overloaded. Changes now start to be apparent within the tendon structure and a matrix breakdown can start to be observed. Although we may intervene with conservative management, this may take a little longer when compared to the reactive phase. 

Degenerative tendinopathy – In this phase there may be multiple changes to the tendon’s structure due to chronic overload (over a prolonged period of time). This is more typical in older athletes and populations. Sometimes the tendon can appear thicker visually or to the touch and is where the collagen has become more disorganised and have advanced tendon matrix breakdown. This can lead to the tendon becoming unable to tolerate loads.

As the injury moves through the phases on this continuum, the rehabilitation usually becomes a little more complex and problematic. This simply means that the earlier we are able to intervene with conservative management and a suitable loading strategy, the better and faster the outcome of recovery may be (7). For optimal rehabilitation and recovery, it is important to identify the stage of injury (along the continuum), assess functional ability, take into account fitness levels and individual biomechanics and extrinsic factors that may be contributing to your pain (7).

There are many factors that contribute to the development of PT and these are known as intrinsic risk factors and extrinsic risk factors (15).

Intrinsic risk factors are internal such as the biomechanics of an individual and include (9):

• Impaired lower limb muscle flexibility such as quadriceps, hamstring and iliotibial band (ITB).
• Reduced muscular strength in the quadriceps muscle
• Anatomical alignment such as the inferior pole of the patella to the hip known as an increased Q-angle, leg length discrepancies, and possibly foot arch height.
• Reduced joint range of motion in the ankle predominantly dorsiflexion

Extrinsic risk factors are external such as the environment and include (9):

• Skill level of the athlete participating in sport
• Level of sports played (beginner or elite)
• Type of sport
• Training surface
• Training and competition loads (frequency, intensity, time and type)

Rehabilitation of PT can also be associated with the stage of the progression the tendon injury falls into, the more chronic the complaint, the longer the rehabilitation process may take (14). No matter what type of PT you have, the key words you may hear amongst the next few paragraphs is load management (5). It would be impossible to generate a specific rehabilitation programme that fits all as this would ideally be individualised incorporating the criteria above that relates to you (6). This is how your clinician clinically rationalises your individual rehabilitation programme (11). It is our aim however, to provide you with the most current and relevant rehabilitation guidance that will help you on your journey to recovery. All of the advice below has been thoroughly researched and forms an evidence-based approach to your treatment and conservative management choices (11). This basically means that you can trust that the information we are sharing with you because it comes from a scientifically tested and proven source. 

Phase 1: De-load (reduce frequency, intensity, time or type of exercise), Ice and start phase 1 exercises. Remove aggravating activities or sport. The main aim of this phase is to control and manage pain, restore function and start loading in a gentle way by using isometric strengthening of the quadriceps muscle (4). Quality stretches to the hip flexors and hamstring muscles are also important (15). Increasing range of motion in your ankle may also prove beneficial. 

Phase 2: Continue to de-load aggravating activity. If pain allows introduce low impact cardiovascular exercises such as swimming or cycling (15). Introduce Isotonic exercises such as leg press or extension if pain allows and heavy slow resistance has been recommended for this phase (13). We are now trying to start loading the tendon whilst still controlling and managing pain. 

Phase 3: Loading by increasing functional strength. This is where your rehab programme becomes more functional possibly adding in strength and conditioning to address biomechanical imbalances that we have found (13). This may include hip, core and lower limb strengthening (2). Eccentric strengthening is introduced as pain allows and evidence suggests the intervention of a decline board may be beneficial (17). 

Phase 4: Return to sport. This is completed as a gradual approach as the tendon tolerates increased load. A decline squat board may be introduced in this phase and a maintenance programme is vital to maintain the integrity of the tendon, correction of biomechanical imbalances, maintain adaptations in flexibility and joint range of motion (16). 

Manual therapy and alternative interventions:

The evidence from the literature suggests that a well-designed and individualised exercise rehabilitation programme consisting of eccentric loading, is more likely to result in positive outcomes in the treatment of PT (7). There are however many manual therapy approaches and orthopaedic interventions that either work alongside exercise rehabilitation programmes to aid patients with symptomatic relief. These include massage (3), acupuncture, taping, extracorporeal shockwave therapy (ESWT) and injections (8). There is however mixed evidence to support these manual therapies alone and successful treatment outcomes have only been reported when these therapies have been combined with an individualised load management and exercise rehabilitation programme (8). It should be noted that the duration of rehabilitation programmes will vary depending on individual factors such as the stage of tendinopathy, intrinsic and extrinsic contributing risk factors and level of sport. The duration of these programmes can vary from 4-6 weeks if only mild-moderate symptoms are present, but for more chronic and degenerative tendinopathies, 12 weeks been suggested as an optimal time frame for return to full function and/ or sport (4).

More invasive treatments such as ESWT and injection therapy (including PRP and steroid injections), have been suggested to be the treatments of choice if conservative management involving a load management exercise programme fail (18). Although some success has been reported with the use of ESWT for many tendinopathies of the body including the patella tendon, it must be emphasised that success has only been shown when combined with a supervised exercise rehabilitation programme (10). Other treatment modalities may be as simple as reviewing current footwear, implementing corrective orthotics if applicable and reviewing environmental factors such training surface and terrain. 

Key points from this article: 

If pain is felt on or after activity at the anterior (front) knee, stop exercise and start phase 1 rehabilitation. Ice alongside isometric quadricep exercises for PT have been shown to be a beneficial strategy in pain management throughout all stages of rehabilitation (12). Gradually progress through the stages but make sure a review of your training, exercise and competition schedule has been completed to try and identify if poor load management is present (7). Make sure your rehabilitation programme takes into account all modifiable risk factors such as biomechanics and aims to correct imbalances such as hip and core stability and strength (2).

References:

[1] Clayton, P. (2015). Tendinopathy Loading Programmes: An Overview of Current Concepts. SportEX Medicine, 64, pp 28-32.

[2] Lack, S. (2015). Proximal Intervention for Management of Patellofemoral Pain. Co-Kinetic Journal, 63, pp 22-26.

[3] Lawrence, D. (2018). Massage for tendon Pain. Co-Kinetic Journal, 77, pp 25-31. 

[4] Lim, H.Y., Wong, S.H. (2018). Effects of Isometric, Eccentric, or Heavy Slow Resistance Exercises on Pain and Function in Individuals with Patellar Tendinopathy: A Systematic Review. Physiotherapy Research International, 23, pp 1-15. 

[5] Malliaras, P., Palmino, J.R., Barton, C.J. (2018). Infographic. Achilles and Patella Tendinopathy Rehabilitation: Strive to Implement Loading Principles Not Recipes. British Journal of Sports Medicine, 52(19), pp 1232-1233

[6] Malliaras, P., Cook, J., Purdam, C., Rio, E. (2015). Patella Tendinopathy: Clinical Diagnosis, Load Management, and Advice for Challenging Case Presentations. Journal of Orthopaedic & Sports Physical Therapy, 45(11), pp 887-898.

[7] Mascaro, A., Cos, M.A., Morral, A., Roig, A., Purdam, C., Cook, J. (2018). Load Management in Tendinopathy: Clinical Progression for Achilles and Patella Tendinopathy. Apunts Medicina L’Esport, 53(197), pp 19-27.

[8] Mendonca, L.M., Leite, H.R., Zwerver, J., Henschke, N., Branco, G., Oliveira, C. (2019). How Strong is the Evidence that Conservative Treatment Reduces Pain and Improves Function in Individuals with Patella Tendinopathy? A Systematic Review of Randomized Controlled Trials Inducing GRADE Recommendations. British Journal of Sports Medicine, 0, pp 1-7. 

[9] Morgan, S., Janse van Vuuren, E.C., Coetzee, F.F. (2016). Causative Factors and Rehabilitation of Patella Tendinopathy: A Systematic Review. South African Journal of Physiotherapy, 72(1),pp 1-12.

[10] Raveendran, K. (2015). ESWT is a force to be Reckoned with. International Journal of Surgery, 24, pp 113-114. 

[11] Reinking, M.F. (2016). Current Concepts In the Treatment of Patella Tendinopathy. The international Journal of Sports Physical Therapy, 11(6), pp 854-865.

[12] Rio, E., Kidgell, D., Purdam, C., Gaida, J., Moseley, G.L., Pearce, A.J., Cook, J. (2015). Isometric Exercise Induces Analgesia and Reduces Inhibition in Patella Tendinopathy. British Journal of Sport Medicine, 49, pp 1277-1283.

[13] Rudavsky, A., Cook, J. (2014). Physiotherapy Management of Patella Tendinopathy. Journal of Physiotherapy, 60, pp 122-129. 

[14] Rutland, M., O’Connell, D., Brisme, J.M., Sizer, P., Apte, G., O’Connell, J. (2010). Evidence-Supported Rehabilitation of Patella Tendinopathy. North American Journal of Sports Physical Therapy, 5(3), pp 166-178.

[15] Sprague, A.L., Smith, A.H., Knox, P., Pohlig, R.T., Silbernagel, K.G. (2018). Modifiable Risk Factors for Patella Tendinopathy in ASthletes: A Systematic Review and Meta-Analysis. British Journal of Sports Medicine, 52, pp 1575-1585.

[16] Willy, R.W., Meira, E.P. (2016). Current Concepts in Biomechanical Interventions for Patellofemoral Pain. The International Journal of Sports Physical Therapy, 11(6), pp 877-888.

[17] Young, M.A., Cook, J.L., Purdam, C.R., Alfredson, H. (2005). Eccentric Decline Squat Protocol offers Superior Results at 12 Months Compared with Traditional Eccentric Protocol for Patella Tendinopathy. British Journal of Sports Medicine, 39, pp 102-105. 

[18] Zwerver, J., Hartgens, F., Verhagen, E., Worp, H., Akker-Scheek, I., Diercks, R.L. (2011). The American Journal of Sport Medicine, 39(6), pp 1191-1199.