Sensory innervation of the knee joint: a narrative review of articular branch mapping and sensory receptor distribution

BACKGROUND: Painful knee conditions impose a substantial socioeconomic burden and remain a diagnostic and therapeutic challenge. The distribution of nociceptors within the knee joint is poorly characterized, with no established consensus. This narrative review aimed to (1) describe the distribution of sensory receptors across intra-articular and periarticular knee structures and (2) characterize the articular branches contributing to the innervation of knee structures in order to inform targeted pain management strategies. METHODS: We conducted a structured narrative review based on a systematic literature search performed in PubMed, Embase, Scopus, Cochrane Library, and Google Scholar (1945-2025). Studies investigating sensory receptor distribution and articular innervation of healthy human knees using dissection, histology, immunohistochemistry, or nerve tracing were included. Two reviewers independently screened, extracted data, and synthesized findings. Outcomes included mapping of parent nerves and articular branches, and semi-quantitative assessment of nociceptor distribution. RESULTS: Among 2222 records, 32 studies were included. Nociceptor distribution showed marked spatial heterogeneity, with the anterior capsule exhibiting the highest density. The posterior cruciate ligament demonstrated greater nociceptor density than the anterior cruciate ligament, whereas menisci and periarticular tissues showed lower densities. Knee innervation consistently arose from the femoral, sciatic, and obturator nerves, with significant overlap and anatomical variability. Major sensory contributors included the saphenous nerve, nerves to the vasti, tibial articular branches forming the popliteal plexus, the common fibular nerve, and obturator branches. CONCLUSION: Knee sensory innervation arises from a complex and overlapping network involving femoral, sciatic, and obturator articular branches. The anterior capsule represents the principal nociceptive region of the knee, whereas mechanoreceptors are predominantly concentrated within cruciate ligaments and peripheral meniscal structures. These findings provide an anatomical basis for refining targeted analgesic and interventional strategies. PROSPERO REGISTRATION NUMBER: 1107530.