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.