Disclosures: Cindy C. Tiu, DO: No financial relationships or conflicts of interest

Case Diagnosis: A 59-year-old male with refractory right anterolateral knee pain.

Case Description or Program Description: A 59-year-old male with mild tri-compartmental osteoarthritis and chronic lateral collateral ligament (LCL) sprain presented with complaints of lateral knee stiffness, instability, and severe anterolateral knee pain. He had failed previous treatments including physical therapy, intra-articular steroid and viscosupplementation injections, genicular nerve blocks, and an ablation. He required tramadol daily. Initial treatment included an ultrasound-guided intra-articular knee injection and LCL injection with platelet-rich plasma. Three months post injection, he reported 50% improvement in diffuse knee pain and knee stability but no change in his anterolateral knee pain. A diagnostic ultrasound examination localized pain to the lateral retinaculum. The patient was treated with 2 separate ultrasound-guided hydrodissection injections (one diagnostic block and one steroid injection). For the therapeutic steroid injection, 2 cc of 1% lidocaine and 1 cc of dexamethasone (4mg/ml) was injected above and below the lateral retinaculum, which was carefully hydrodissected away from the overlying tissue below to block the lateral retinacular nerve (LRN). He received complete resolution of focally exquisite right anterolateral knee pain immediately after both the diagnostic block and steroid injection. He additionally stopped use of narcotics.

Setting: Outpatient clinic

Assessment/Results: At 3 months post-injection, the patient continued to demonstrate complete resolution of right lateral retinacular pain. Further developments will be discussed.

Discussion (relevance): This case highlights the contribution of the lateral retinacular nerve in anterolateral knee pain despite the paucity of evidence about nerve blocks targeting this nerve.

Conclusions: Despite poor documentation of lateral retinacular nerve blocks, it is a potentially efficacious surgery-sparing treatment option for those with refractory anterior knee pain that localizes over the lateral retinaculum.

Level of Evidence: Level IV

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PM&R Meeting Abstracts - https://pmrjabstracts.org/abstract/treatment-of-lateral-retinacular-knee-pain-with-ultrasound-guided-nerve-block-and-hydrodissection-a-case-report/