Ultrasound-Guided Manual Therapy for the Infrapatellar Branch of the Saphenous Nerve Entrapment Presenting as Anterior Knee Pain: A Case Report

The infrapatellar branch of the saphenous nerve (IPBSN) is the sensory branch that supplies the anteromedial knee. While iatrogenic injury following knee surgery is well documented, spontaneous or activity-related IPBSN entrapment is under-recognized and can mimic common extensor mechanism disorders. Herein, we present the case of a male physical education teacher in his 20s who developed reproducible anterior knee pain with lunge movements after repeated basketball jumps. The initial clinical suspicion was patellar tendinopathy; however, high-resolution ultrasound (HRUS) revealed IPBSN entrapment at the sartorius penetration site. Manual decompression of the sartorius muscle immediately alleviated the pain. Subsequently, ultrasound-guided soft tissue mobilization was performed, resulting in complete resolution of pain. This case highlights the diagnostic value of HRUS and introduces ultrasound-guided manual therapy as a potentially safe and effective conservative option for treating IPBSN presenting with anterior knee pain.