A 35-year-old Caucasian male presented with discomfort and pain in the popliteal area of the right knee that had persisted for 11 years, without a history of trauma. He complained of pain progression from sporadic to continuous, intermittent swelling, and decreased ROM for the last 3 years. The medical history of the patient was unknown and not reported during the first medical examination. He reported he had undergone a surgical procedure to his knee because of the pain, 4 years before, without any significant relief of the symptoms. The surgical report documented an arthroscopic synovectomy combined with medial meniscus partial meniscectomy for a peripherical lesion through the standard anteromedial and anterolateral portals. After the surgery he continued to use painkillers, but no improvement of ROM has been registered. Our first physical examination revealed swollen knee, tenderness to palpation, decreased ROM (15–80°), and valgus limb alignment. Anterior–posterior and varus/valgus stress stability were preserved. No meniscal signs and focal neurologic deficits were reported. The symptoms were exacerbated upon deep flexion. On occasions, he could not walk or go up and down stairs owing to pain and articular locking. Weight-bearing radiographs showed advanced stage of osteoarthritis (Kellgren–Lawrence stage II–III), mild valgus limb alignment, and multiple loose bodies in the posterior compartment. In order to accurately localize the loose bodies in the posterior compartments of the knee, a MRI was performed. MRI scan is able to characterize synovial lesions, owing to their high resolution of soft tissue [, ] and non-calcified cartilage nodules. It revealed diffuse chondropathy, minimal synovial hypertrophy areas, multiple osteophytes in the intercondylar notch, and more than 30 low density loose radio dense bodies in the posteromedial compartment. Owing to this, we classified the SC as stage III according to Milgram []. Considering the high grade of osteoarthrosis, we felt confident in performing a CT scan to better define the location of the osteophytes, the signs of osteoarthritis such as narrowing of the joint space and bone spurs, and the presence of calcifications and calcified loose bodies. In detail, the CT scan documented the bony structures, the morphology of the intercondylar notch, and the presence of osteophytes localized to the anterior and posterior side of the medial and lateral femoral condyles, allowing for a meticulous planning on how to reach the posterior compartment of the knee, passing anterior to posterior through a trans-notch passage. Even though the radiological exams showed an advanced grade of arthritis, the patient’s age and the desire for a full functional recovery drove us to perform a less invasive procedure than a total knee replacement, with the aim to preserve his native joint. For this reason we chose an arthroscopic procedure, considering that the large amount of loose bodies in the posterior knee might be the reason for the limited ROM and recurrent synovitis. The patient underwent an arthroscopic surgical approach 2 months after our first examination. Under spinal anesthesia, 2 g of intravenous cephalosporin was administered before inflation of a thigh tourniquet. The patient was placed supine on the operating table with the operative leg hanging in a 90° flexion position. A lateral post was placed just proximal to the knee at the level of the padded tourniquet, and a foot roll to prevent the hip from externally rotating and to maintain 90° of knee flexion. An arthroscopic examination of the anterior knee compartment was performed using conventional anteromedial (AM) and anterolateral (AL) portals, close to the patellar tendon border to facilitate passage of the arthroscope or instruments through the intercondylar notch. Multiple osteophytes were localized on the lateral side of medial femoral condyle, interfering with the trans-notch arthroscope passage. Meticulous debridement, removal of anterior osteophytes and a few anterior loose bodies that probably escaped from the posterior compartment, and tunneling, using a burr through the intercondylar osteophytes, were performed to allow the arthroscope to pass trans-notch. We performed the modified Gillquist maneuver [] to reach the posteromedial knee compartment. The arthroscope from AL portal was introduced into the posteromedial compartment through the intercondylar notch, passing between the lateral border of the medial femoral condyle and the medial border of the posterior cruciate ligament, with the knee in 90° of flexion. The posteromedial (PM) portal was than created under the guidance of trans-illumination by the light source introduced into the AL portal, with the intent to prevent injury to the neurovascular structures. With the arthroscope in the AL portal, the forceps were introduced through the PM portal and all the loose bodies were removed. To avoid additional accessory posterior portals, we used a 70° arthroscope to better explore the posteromedial knee compartment. To complete the procedure, synovectomy of the inflamed areas was performed to remove the active synovial proliferative tissue. A total of 33 loose bodies were removed from the posteromedial compartment. A final radiographic control documented the result of the procedure. Rehabilitation to recover ROM and full weight-bearing were permitted on postoperative day 1. Anti-thromboembolic prophylaxis, antibiotic prophylaxis, and pain killers were recommended. The patient was discharged on postoperative day 1. Histological examination showed that the loose bodies were composed mainly of hyaline cartilage embedded in the connective tissue, which confirmed the diagnosis of SC. After 1 month, pain and swelling were limited. ROM was 5–90° and the anteroposterior and varus/valgus stability was maintained. After 3 months, the wound was completely healed without swelling of the knee. The patient reported pain only during high demanding activities and ROM was 0–110°. At 12 months of FU, the patient was pain free with a complete recovery of ROM, and was able to participate in some light sport activity. The Tegner Lysholm Knee scoring scale was excellent (95/100 points). No recurrence of swelling or locking symptoms were reported.