The Thermo-LCA study is a diagnostic interventional study for assessment of knee temperature of asymptomatic patients with ACL reconstruction compared with unoperated healthy contralateral knee. The aim of the study is to analyze thermographic images obtained from the knees of asymptomatic patients with ACL reconstruction that occurred between the previous 2 and 5 years, to assess the presence of inflammation in the knee with reconstructed ACL compared with the contralateral.

Thermo-LCA study involves recruitment of thirty volunteers with unilateral ACL reconstruction Will be enrolled subjects aged 18 to 40 years, with no history of previous surgery or chronic gonalgia in the contralateral knee. Once the patient's Informed Consent has been obtained, the patient will wait sitting 10 minutes inside the temperature-controlled room of 23°C, a thermographic assessment will then be performed using a FLIRT1020 thermal imaging camera. Photographs will be acquired in anteroposterior, right lateral, left lateral, and posteroanterior views of both knees. The patient will then perform a knee flexion-extension exercise against resistance for 2 minutes using a 2 kg weighted ankle monitor. The speed at which this exercise is performed will be constant for all subjects, with one repetition per second per leg. Following this exercise, four more thermographic images identical to the first will be acquired. Basal thermographic assessments will be performed at 5', 10' and 20' minutes after the end of the exercise.Once the images are acquired these will be analyzed using ResearchIR software, regions of interest of the knees will then be constructed and their temperature change over the various acquisitions and how it changes after physical exertion will then be analyzed.

Inclusion Criteria:

1. Male or female patients aged between 18 and 40 years;
2. Asymptomatic at the time of evaluation (IKDC ≥95);
3. No history of previous surgery or contralateral knee fractures;
4. No history of direct or indirect trauma in the previous six months to either knee;
5. Absence of gonalgia (VAS pain equal to 0) at evaluation;
6. BMI between 18.5 kg/m2 and 29.9 kg/m2.

Exclusion Criteria:

1. Patients who are incapacitated or have neurological disorders that may invalidate the research protocol;
2. Diagnosis of leukemia, known presence of metastatic malignant cells, current or planned chemotherapy;
3. Diagnosis of rheumatoid arthritis, Reiter's syndrome, psoriatic arthritis, gout, ankylosing spondylitis or arthritis resulting from another inflammatory disease; human immunodeficiency virus (HIV) infection, viral hepatitis; chondrocalcinosis;
4. Patients with uncontrolled diabetes mellitus;
5. Patients with uncontrolled thyroid metabolic disorders;
6. Patients abusing alcoholic beverages, drugs, or medications;