The aim of our study was to investigate the accuracy of dynamic ultrasound assessment of the anterior tibial translation, in diagnosing anterior cruciate ligament tears, and to assess its test–retest reliability. Twenty-three patients (32 ± 8.42 years; 69.56% males) with a history of knee trauma and knee instability participated in the study. Knee ultrasound was performed by an experienced orthopedic surgeon. The anterior tibial translation was measured in both knees and differences between the injured and uninjured knee were calculated. Side-to-side differences > 1 mm were considered a positive diagnosis of an ACL tear. The anterior tibial translation values were 3.34 ± 1.48 mm in injured knees and 0.86 ± 0.78 mm in uninjured knees. Side-to-side differences > 1 mm were found in 22 cases (95.65%). The diagnosis accuracy was 91.30% (95%CI: 71.96–98.92%) and sensitivity 95.45% (95%CI: 77.15–99.88%). The intraclass correlation coefficient showed an excellent test–retest reliability (ICC_3,1 = 0.97 for the side-to-side difference in anterior tibial translation). The study highlights the accuracy and reliability of the dynamic ultrasound assessment of the anterior tibial translation in the diagnosis of unilateral anterior cruciate ligament tears. Ultrasound assessment is an accessible imaging tool that can provide valuable information and should be used together with physical examination in suspected cases of ACL injuries.

Brodie’s abscess is a rare form of sub-acute osteomyelitis that implies the collection of pus inside bone tissue. The present paper presents an extremely rare case of Brodie’s abscess located in the distal femur in a young male patient who refused medical care for three years and presented directly with spontaneous fistula and septic complications. Laboratory tests also suggested chronic septic alterations. Complex imaging investigations including X-ray (RX), computer tomography (CT) and Magnetic Resonance imaging (MRI) confirmed the diagnosis with characteristic aspects, such as the penumbra sign on the T1 weighted MRI image. Management included aggressive debridement, defect reconstruction, and long-term specific antibiotics according to culture harvested intra-operatively. Evolution was positive with inflammatory blood tests returning to physiological values within four weeks and patient full recovery within six months, without any physical deficits. The novelty aspect found in this case presentation is represented by the long-term natural evolution of this pathology, and the fact that even in these conditions, the Brodie’s abscess did not evolve into a ‘malignant’ septic condition, but remained rather benign until the spontaneous fistula prompted the patient to seek medical care.