Patellar tendinopathy in sport: epidemiology and treatment

Patellar tendinopathy is a very common injury in sports such as cycling, football or basket, although it can also affect sedentary people whose activity requires active participation of the knee joint. The function of patellar tendon serves as a link between the patella and tibia and is key for the knee extension, as well as other activities such as jumping, bending, going up and down stairs.

This injury does not usually develop inflammation as it is degenerative. The injured tendon shows hypercellularity with an atypical proliferation of fibroblast and endothelial cells among the vascularization. There is a lack of longitudinal collagen fibers, with gaps between their fibers, a rupture of collagen fibers. Assessing the tendon irritability is critical in patellar tendinopathy to determine the severity of symptoms after energy storage and release activities (e.g., sprints, jumps, changes of direction).

Symptoms

Patellar tendinopathy injury is characterized by a stabbing pain under the patella, deep to the tendon. The pain is more pronounced on the knee flexion or when performing any action that requires knee strength. Depending on the severity of the injury, pain may be a limiting factor and prevent full flexion of the knee or the practice of any sporting activity. Early intervention and an adequate rehabilitation program are paramount to avoid aggravation of the injury and chronicity, when the recovery process will be longer and more difficult.

Patellar tendinopathy usually begins with a ‘mild discomfort’ during activity, which ceases immediately after exertion. It is very common ‘not to give it importance’, but if an appropriate rehabilitation program is not performed and the injury becomes symptomatic, the recovery is more difficult since there will be a progressive degeneration of the tendon and the pain will increase, even breaking the tendon. 

Common causes of patellar tendinopathy

• Stiffness of leg muscles, with shorter ranges of motions.
• Repetitive stress caused by microtrauma, such as continuous landings and jumps (e.g., volleyball) or constant pedalling. 
• Inadequate load adaptations or progressions. 
• Deficient body posture or poor technique. 

In conclusion, all situations involving excessive stress on the tendon that may lead to inflammation or microtears.

Schwartz et al. (2015) establishes the following risk factors:

• Increased weight. 
• Wrist-hip ratio.
• Asymmetry in leg length. 
• Height of foot arc.
• Strength and flexibility of quadriceps. 
• Flexibility of hamstrings.
• Sports involving continuous jumping and landing.

Treatment of patellar tendinopathy 

The treatment of patellar tendinopathy must be individualized due to the affectation, aggravation, causes and specific requirement of each person can be very different. Consequently, recovery time can vary significatively. If the injury is not advanced and timing of intervention is adequate, recovery does not have to be a long process and even the treatment can be combined simultaneously with the specific practice by reducing the volume of load. There are studies showing that one third of athletes with patellar tendinopathy return to play after 6 months (Malliaras et al., 2015). However, if the treatment is not appropriate or the injury becomes chronic, the recovery process is very tedious and lengthen up to 12-18 months. Finally, the literature shows that 53% of athletes retire after this injury.

The recovery process of patellar tendinopathy may be slightly painful for the athlete as the intensity or load of the exercises will be regulated according to his subjective perception of pain. In this sense, pain rating with the visual analogue scale (VAS) is a good method to evaluate the workload. 

I usually work with an athlete’s pain perception of 3-5 on the VAS (Malliaras et al., 2015), especially early in the recovery process. Nonetheless, this can vary depending on the athlete, severity of the injury, competition demands and the risk you are willing to take. Anyways, I do not consider appropriate to exceed 6 on the VAS. 

Appropriate guidelines in the treatment of this injury:

• Reduce the load volume. 
• Isometric contractions at 30-60º (especially early in the recovery process).
• Slow contractions with high resistance.
• Eccentric contractions of quadriceps.
• Eccentric squat on declined surface of 20-25º, eliminating the concentric phase of movement. 
• Strength exercises with closed kinetic chain.
• Strengthening and stretching of the musculature implicated in the flexion-extension of the knee (quadriceps and hamstrings) to complete the full range of motion.
• Progression from bilateral to unilateral exercises.
• Progression by increasing the speed of execution and towards SSC exercises.
• Assess unilateral strength with declined 90º-squat test using the VAS immediately- and 24 hours after the exercise. 
• Application of ice to the affected area. 
• Combine training and physiotherapy. 

Below, I propose a generic exercise program for the rehabilitation of patellar tendinopathy for the initial stages of the process. It is recommended to perform this program 3 times per week and progress gradually increasing the load and speed of execution, and towards from bilateral to unilateral movements. The principles of individualization and progression of the load must be considered for an optimal rehabilitation process. In addition, as previously mentioned, reducing the volume of activity is key in the recovery of this injury.

Exercise	Sets/Reps
Ankle dorsal flexion	3x15reps each leg
Seated straight Leg Raise (overloaded)	6×20” each leg
Isometric bilateral squat (overloaded)	4×45” / 60” Recovery
Eccentric bilateral squat on declined surface (20-25º)	4x10reps / 45-60” Rec
Eccentric unilateral squat on declined surface	3×6-8reps / 45-60” Rec
One-leg stability on bosu	4×25” each leg / 20” Rec
Alternating front lunges	4x16reps / 30” Rec

References

• Clifford, C., Challoumas, D., Paul, L., Syme, G., & Millar, N. L. (2020). Effectiveness of isometric exercise in the management of tendinopathy: a systematic review and meta-analysis of randomised trials. BMJ Open Sport & Exercise Medicine, 6(1), e000760. 
• 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(4), 1–15.
• Malliaras, P., Cook, J., Purdam, C., & Rio, E. (2015). Patellar tendinopathy: Clinical diagnosis, load management, and advice for challenging case presentations. Journal of Orthopaedic and Sports Physical Therapy, 45(11), 887–898. 
• Muaidi, Q. I. (2020). Rehabilitation of patellar tendinopathy. Journal of Musculoskeletal Neuronal Interactions, 20(4), 535–540.
• Murtaugh, B., & M. Ihm, J. (2013). Eccentric Training for the Treatment of Tendinopathies. Current Sports Medicine Reports, 12(3), 175–182. 
• Schwartz, A., Watson, J. N., & Hutchinson, M. R. (2015). Patellar Tendinopathy. Sports Health, 7(5), 415–420. 
• Van Ark, M., Van den Akker-Scheek, I., Meijer, L. T. B., & Zwerver, J. (2013). An exercise-based physical therapy program for patients with patellar tendinopathy after platelet-rich plasma injection. Physical Therapy in Sport, 14(2), 124–130. 

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This article has been made based on the references showed, other studies reviewed but not showed and according to the experience and knowledge of the author. In this way, it may include subjective ideas and opinions not contrasted in the research.