Knee Bursae: A Comprehensive Review of Clinical Evaluation, Imaging Differentiation, and the Expanding Role of Biologic Therapies

BackgroundKnee bursae are potential sources of anterior, medial, lateral, and posterior knee pain, yet many remain under-recognized in clinical practice. Emerging biological therapies offer promising, minimally invasive options for resistant bursitis, but high-level evidence is limited for several bursal types.PurposeTo systematically review the anatomy, clinical presentation, imaging characteristics, treatment strategies, and outcomes of 11 distinct knee bursae, with emphasis on the role of biologic therapies.MethodsThis systematic review followed PRISMA guidelines. PubMed and Embase were searched (2000-2024) for studies addressing anatomy, diagnosis, imaging, treatment (conservative, injection-based, biologic, or surgical), and outcomes of knee bursae. Studies involving human subjects, published in English, and reporting clinical, imaging, or therapeutic data were included. Levels of Evidence (LOE) were assigned using Oxford criteria.ResultsA total of 76 studies were included. Several randomized controlled trials (LOE I) focused on pes anserine and OA-related bursitis, while additional Level II studies assessed PRP and corticosteroids. Data on rare bursae (e.g., LCL, deep infrapatellar) were primarily derived from imaging reviews and case series (LOE III-IV). Corticosteroid injections showed recurrence rates of 20% to 40%. PRP and PRP+HA demonstrated improved pain relief and reduced recurrence in selected bursae, although protocols remain heterogeneous.ConclusionConservative management remains first-line for most bursae. PRP-based therapies, especially in pes anserine and OA-related bursitis, offer promising alternatives in refractory cases. Although several Level I-II studies support their efficacy, additional high-quality RCTs are warranted-particularly for understudied bursae.