Attending Physician Swedish Spine Sports and Musculoskeletal Medicine Seattle, Washington, United States
Case Diagnosis: Compressive Common Fibular Neuropathy
Case Description: 56 year old male with previous right knee replacement presented to the office with right foot weakness, numbness, and pain. Symptoms started almost immediately after his revised right knee replacement. On a 4-month follow-up, he was found to have dorsiflexion and toe extension weakness. He was referred for an electrodiagnostic study to evaluate the extent of neuropathy.
Conduction study revealed moderate to severe conduction block of the right common fibular nerve. Electromyography showed signs of denervation in the distal fibular innervated muscles. An ultrasound study was done to evaluate the common fibular nerve at the fibular head to asses for focal compression. Imaging showed significant, focal enlargement of the common fibular nerve at the fibular head. Common fibular nerve hydrodissection was performed to determine if this would relieve symptoms. There was a resolution in symptoms and near-full motor recovery except for minimal persistent toe numbness and great toe weakness.
Discussions: Postoperative peripheral nerve injuries are uncommon (around 0.03%), self-limiting, and most of the time can be managed conservatively with no serious permanent neurological deficit. Hydrodissection is still a fairly new non-surgical technique used in treating nerve entrapments. This is a case where conservative management failed and with the use of ultrasound-guided hydrodissection, obtained resolution of symptoms and near-full motor recovery.
Conclusions: This is a unique case, highlighting ultrasound-guided hydrodissection as a potential intervention for those who fail conservative treatment rather than surgical decompression. Nonsurgical intervention such as hydrodissection has the potential to provide motor and sensory recovery and reduce the risks that come with surgical decompression such as infection, worsening neuropathy, CRPS, and periprosthetic fracture just to name a few.
