Associate Professor Indiana University Zionsville, Indiana, United States
Case Diagnosis: Immunotherapy causing knee pain in a patient with malignant melanoma.
Case Description: A 50-year-old male with a history of malignant melanoma, metastatic disease s/p chemotherapy and radiation, presented with severe knee pain. He had undergone immunotherapy with pembrolizumab and ipilimumab; these agents are well-known to cause arthralgias including inflammatory arthritis. Imaging of his knee showed mild degenerative changes. The pain was refractory to physical therapy, bracing, topical and oral analgesics (including opioids), corticosteroid injections, and viscosupplementation. Orthopaedics determined he was not a surgical candidate, given the lack of response to intra-articular interventions. The patient then underwent successful fluoroscopically guided genicular nerve blocks at three sites with subsequent radiofrequency denervation at the same sites. He experienced complete resolution of knee pain at 6- and 12-month follow-up. He required no pain medication for knee pain. He was able to participate fully in therapeutic exercises and relied less on assistive devices.
Discussions: Treatments for metastatic melanoma may involve agents which are known to cause arthralgias. This case demonstrated that fluoroscopic-guided genicular nerve ablation may be an effective treatment in patients who do not respond to more conservative measures.
Conclusions: Geniculate nerve block and subsequent radiofrequency neurotomy may be an effective option for pain management for patients with arthralgias secondary to antineoplastic agents.