Ultrasound Probe Pressure on the Intratendon Doppler Signal in Patellar Tendinopathy

Evaluation of the Influence of Ultrasound Probe Pressure on the Intratendon Doppler Signal in Patellar Tendinopathy

In the sports field, patellar tendinopathy is, as a pathology, one of the main concerns for athletes, both because of its incidence and because of the difficulty involved in their recovery. At the ultrasound level, tendinopathies can be divided, depending on the presence or absence of an intratendon Doppler signal, into hypervascular or hypovascular tendinopathy. Its classification is, today and clinically speaking, merely qualitative through the observation of the explorer. The ultrasound evaluation is carried out through a probe that is placed on the patient's skin, the procedure to be followed to obtain a vascular image is merely operator-dependent, that is, the position of the probe, the pressure exerted on the skin or even ultrasound optimization parameters can drastically modify the results. Due to high pressure on the probe, the intratendon Doppler signal may be diminished in the quantitative variables of area, number of signals, pixel intensity, perimeter, solidity, perfusion index, circularity, major and minor diameter. From a certain pressure on the probe, the intratendon Doppler signal can be drastically altered. This study will try to evaluate the influence of the pressure exerted by the examiner with the probe on the quantitative variables of the intratendon Doppler signal in patellar tendinopathy. To carry out the study, a single group with patellar tendinopathy will be established. Ultrasound evaluations with Doppler mode will be performed on the tendon using different probe pressures, monitoring the applied force and recording the images obtained for later analysis.

Intratendon vascularization will be quantified using a proprietary methodology using ImageJ 1.47v image analysis software, determining the different variables related to the Doppler signal within an intratendon region of interest.

Ultrasonic exploration by power-Doppler of the intratratendon vascularization, making longitudinal cuts of the patellar tendon and with previously pre-established Doppler optimization parameters for all patients. The optimization parameters of the power-Doppler signal will be set at a Doppler frequency of 6.7 MHz, pulse repetition frequency (PRF) of 0.7 kHz. The lowest wall filter and a standardized gain just below the level that produces random noise will be applied. This examination will be repeated several times with different probe pressures, which will be quantitatively adjusted through the force sensor and maintained with the articulated arm. A 4-second static video will be recorded of the longitudinal section that presents a higher Doppler signal in each of the scans at different probe pressures.

Location of pain in the patellar tendon (lower pole of the patella-body of the tendon-insertion in the anterior tuberosity of the tibia)

Knee pain and function rating scale (0-100 Units on a scale). The maximum score possible is 100 points and represents an asymptomatic athlete who can fully engage in sports. The theoretical minimum is 0 point. The test is carried out just before the intervention to relate the results of the Doppler quantification with the severity of the pain.

Current training hours per week (hours). This question is asked just before the intervention in order to relate the results of the Doppler quantification with the hours of training performed

Inclusion Criteria: Acceptance of participation in the study. Diagnosis of patellar tendinopathy with the presence of an intratendon Doppler signal. Subjects between the ages of 18 and 65. Exclusion Criteria: Present some type of surgical intervention in the region to be explored that could alter in some way the ultrasound evaluation. Refer vascular pathology or the intake of medication that may alter blood flow or density. Having been treated with sclerosing techniques that can alter the perfusion or vascular resistance of the tendon tissue.

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