Introduction

Patellar tendinopathy (PT), also known as jumper's knee, is a common pathology of the patellar tendon, especially among athletes. This condition is characterized by pain in the anterior part of the knee, just below the patella, where the patellar tendon inserts.

The pain usually intensifies with physical activity and can significantly affect an athlete's performance and quality of life. Patellar tendinopathy results from mechanical overload and repetitive microtraumas that exceed the tendon's capacity for repair. This leads to a chronic inflammatory response and degenerative changes in the tendon structure, such as collagen fiber disorganization, increased vascularization, and cell apoptosis.

Athletes with this condition may experience stiffness, swelling, and a decrease in the functional capacity of the knee. The prevalence of patellar tendinopathy in elite athletes across different sports has been estimated to be around 14% (Molina-Payá et al., 2023)​.

Diagnosis and Evaluation

Diagnosis is based on clinical history, physical examination, and the use of imaging techniques such as ultrasound and magnetic resonance imaging to identify structural changes in the tendon.

Ultrasound signs of tendinopathy include increased tendon thickness, loss of collagen fiber alignment, and the presence of neovascularization. However, the use of these techniques requires knowledge and is associated with costs.

Some tools, such as infrared thermography, could be useful in this context due to their ability to detect thermal changes associated with inflammation and increased blood flow in the affected tendon. Infrared thermography is an imaging technique that measures the emission of infrared radiation from the body surface, providing a temperature map of the underlying tissues.

The main advantage of thermography is its non-invasive nature and the absence of ionizing radiation, making it a safe and repeatable option for monitoring injuries. Additionally, it can identify subtle differences in skin temperature that are correlated with underlying inflammatory processes, allowing for early detection of tendinopathy and assessment of inflammation severity.

Study on Thermography and Patellar Tendinopathy

A study by Molina-Payá et al. (2023) evaluated 26 athletes with patellar tendinopathy and 27 asymptomatic athletes using infrared thermography and Doppler ultrasound. Parameters recorded included: Temperature differences, echotexture (echo-intensity-EI and echo-variation-EV), and intratendinous vascular resistance (IVR).

Main Results

Temperature Differences

Absolute temperature differences were significantly higher in the tendinopathy group compared to controls (BF10 = 19). Strong evidence of higher temperature was found on the affected side (BF10 = 14; effect = 0.53°C; 95% CrI = 0.15°C–0.95°C).

Intratendinous Vascular Resistance

Athletes with PT showed significantly reduced IVR compared to controls (BF10 = 71; effect = -0.67; 95% CrI = -1.10 to -0.25). This reduction could be related to the coexistence of degenerative and inflammatory processes in patellar tendinopathy.

Doppler Signal Area and Echotexture

The Doppler signal area and echo-variation were greater in the tendinopathy group (BF10 = 266). Echo-intensity and echo-variation were used as echotextural parameters to differentiate affected from healthy tissues. Echo-variation showed a moderate correlation with VISA-P scores, which measure symptom severity in PT patients.

Conclusions

• The integration of these advanced imaging techniques provides a more complete view of the pathological state of the patellar tendon in athletes, which can improve diagnosis and guide more effective treatment strategies.
• These methods are not only useful for identifying the presence of PT but also for monitoring disease progression and treatment response.
• The temperature differences and reduced intratendinous vascular resistance indicate possible inflammatory processes associated with patellar tendinopathy.

Referencias:

• Molina-Payá, F. J., Ríos-Díaz, J., Carrasco-Martínez, F., & Martínez-Payá, J. J. (2023). Infrared thermography, intratendon vascular resistance, and echotexture in athletes with patellar tendinopathy: a cross-sectional study. Ultrasonic Imaging, 45(2), 47-61.
• de Lacerda, A. P. D., de Andrade, P. R., Kamonseki, D. H., Parizotto, N. A., da Silva, A. S. A., de Medeiros, L. B., & de Almeida Ferreira, J. J. (2022). Accuracy of infrared thermography in detecting tendinopathy: A systematic review with meta-analysis. Physical Therapy in Sport, 58, 117-125.