Fascial plane blocks as diagnostic keys to persistent pain after hip replacement: Sequential PENG and sacral ESP approach

Persistent pain after total hip arthroplasty (THA) remains a diagnostic and therapeutic challenge, often related to extra-articular or neuropathic mechanisms rather than prosthetic failure. We report the case of a 70-year-old female with chronic suprainguinal, anterolateral thigh and gluteal pain who underwent right THA in 2023. Lumbar MRI performed before surgery showed L4-L5-S1 disc protrusions, initially considered incidental. Despite correct prosthesis positioning, postoperative pain persisted identically to preoperative symptoms. A pericapsular nerve group (PENG) block with ropivacaine 0.1% (20 ml) and methylprednisolone 40 mg provided near-complete anterior pain relief within 6 hours. Two weeks later, a sacral erector spinae plane block with ropivacaine 0.1% (20 ml) and methylprednisolone 20 mg, combined with a repeat PENG, achieved complete and lasting pain resolution. At 90-day follow-up, the patient remained pain-free. Thorough preoperative assessment, including diagnostic nerve blocks, may help prevent unnecessary arthroplasty in atypical hip pain.