(Kiosk 2) Post Operative Nerve Entrapment Mimicking Pes Anserine Bursitis Successfully Treated with Hydrodissection

Case Diagnosis: Nerve entrapment due to scar tissue from ACL reconstruction mimicking pes anserine bursitis that was successfully treated with hydro-dissection under ultrasound.

Case Description or Program Description: Patient is a 31 year old male with a history of ACL tear and reconstruction presented to sports clinic with right knee pain that started approximately 6 months prior. Successful ACL reconstruction with bone-patella graft on the knee occurred 1 year prior to presentation. He had no repeat knee injury and stated the pain worsened gradually over time to the point he had significant pain with ambulation. Prior to presentation to clinic, patient complained of pain in the pes anserine area. MSK ultrasound demonstrated tendinopathy of the tendons inserting on the pes anserine. He subsequently underwent a steroid injection to the pes anserine bursa with short-term, limited relief of the pain. Patient was referred for consideration of tendon fenestration and further management after the pain worsened. On exam, the patient had significant pain over the distal incision of the ACL surgery that radiated down the leg. Ultrasound examination of the area demonstrated a nerve adjacent to the tibial periosteum that was painful with palpation of the ultrasound probe. A mixture of saline and lidocaine was used to hydro-dissect the nerve off of the tibia. Patient had complete resolution of pain immediately after the procedure. On a follow up examination 1 month later the patient had sustained resolution of pain and had resumed normal activities.

Setting: Outpatient procedures

Assessment/Results: Patient had complete resolution of pain after hydro-dissection was performed.

Discussion (relevance): The infrapatellar branch of the saphenous nerve has been implicated in ongoing pain after total knee replacement. To our knowledge this is the first case reported after ACL reconstruction. Hydro dissection has good efficacy for treating nerve entrapments.

Conclusions: Nerve entrapment after surgery is a potential cause of ongoing pain that can be successfully treated with hydro-dissection under ultrasound.