A Green Thumb Injury: Anterior Femoral Cutaneous Neuralgia Treated in a Gardener

Case Diagnosis: A 72-year-old woman with chronic right thigh pain found relief after an anterior femoral cutaneous nerve steroid injection.

Case Description or Program Description: A 72-year-old female gardener presented with right thigh pain for one year following hip hyperextension during a fall. The pain was dull and persistent, in the proximal anteromedial right thigh, and rated 5/10 at rest. Pain exacerbated by hyperextension maneuvers including mounting her horse. The patient reported minimal relief with Epsom salt baths and anti-inflammatories. Despite physical therapy, chiropractic manipulation, and stretching, the pain remained refractory.

Setting: Patient seen in resident physician outpatient clinic.

Assessment/Results: Physical examination was significant for pain with hip hyperextension. Diagnostic workup included ultrasound and MRI of the right lower extremity. Ultrasound revealed no significant pathology. MRI demonstrated a partial tear of the right gluteus medius and hamstring tendon.
Given the mechanism of injury, clinical history, and examination findings, anterior femoral cutaneous nerve (AFCN) injury was suspected. A diagnostic and therapeutic ultrasound-guided injection was administered using 1cc dexamethasone 10mg/ml and 1cc lidocaine 1%. At follow-up, the patient reported 80% symptom reduction, with 0/10 pain at rest, though noted with exertion. Physical therapy was prescribed for lower extremity strengthening and management of the incidental tendon tears.

Discussion (relevance): Prior studies describe MRI-guided cryoanalgesia for long-term relief in patients with AFCN-mediated pain, demonstrating significant pain reduction without major complications. Most common causes for AFCN injury include trauma, surgical procedures, or entrapment.
Limitations include the possibility that the partial tendon tears could be pain generators, as hamstring tendon tears can refer pain to the anteromedial thigh.

Conclusions: While musculoskeletal pathologies dominate the differential diagnosis for hyperextension injuries, this case highlights the importance of considering less common nerve injuries. Unlike the well-recognized lateral femoral cutaneous nerve syndrome, AFCN injuries are frequently overlooked. This case highlights an atypical mechanism of injury of the AFCN, during a gardening accident.