Bone marrow edema (BME) is a frequent MRI finding in patients with knee pain. According to the etiology, BME of the knee can be classified into three main categories: ischemic, mechanic, and reactive. The diagnosis may be difficult, because of the specificity of symptoms and the poor radiographic findings. MRI is the gold standard, showing an area of altered signal of the bone with an high signal intensity on fat-suppressed, T2 weighted images, usually in combination with an intermediate or low signal intensity on T1 weighted images. Bone marrow edema tends to be self-limiting and, in most cases, resolves without any consequences in a varying amount of time. However, since it may evolve to complete joint destruction, early diagnosis and correct treatment are crucial to prevent the articular degeneration. Conservative therapy is the first step, with no weight-bearing for 3 to 6 weeks on the affected side, in combination with the administration of anti-inflammatory drugs or painkillers to manage symptoms. In non-responding forms and more advanced stages, minimally invasive preservative surgery can provide significant results, with subchondroplasty and core decompression being the two main procedures available. Knee arthroplasty, both total (TKA) or unicompartmental (UKA), is the only effective option when the degradation of cartilage is diffuse and in patients with subchondral bone collapse.

Diffuse type tenosynovial giant cell tumor (D-TGCT) of the knee presents with stiffness, pain and swelling with surgery being the mainstay treatment. However, the literature lacks data on clinical course of range of motion, pain (ROM), and swelling after open synovectomy for D-TGCT. Therefore, this study aims to evaluate clinical course after open anterior synovectomy. A retrospective analysis was conducted on 214 patients treated for TGCT at our Institutions between 2010 and 2023. 51 patients with anterior knee D-TGCT who underwent open anterior synovectomy were included. Pre- and postoperative assessments included ROM, pain (VAS scale), and reported swelling. The mean knee flexion increased from 100° (SD 14.28) preoperatively to 131.8° (12.64) at 12 months post-surgery. Knee extension remained stable, ranging from 178.4° preoperatively to 179.2° at the final follow-up. Pain decreased from a mean of 5.0 (SD 2.8) preoperatively to 0.5 (SD 0.7) at 12 months. Swelling was initially reported in 90.4% of patients, with 95.74% of them showing improvement at six months, and 100% at 12 months. Open anterior synovectomy effectively improves knee function, pain, swelling in patients with anterior knee D-TGCT, although functional recovery may take up to 6–12 months.