Sciatic nerve compression as a cause of severe chronic pain after total knee replacement: a case report

Persistent pain following total knee replacemnt (TKR) remains a challenging and often multifactorial issue. While common causes include infection, malalignment, or complex regional pain syndrome, less typical origins are easily overlooked. We report a unique case of chronic, disproportionate posterior thigh pain 1 year after TKR, caused by a complete proximal hamstring rupture leading to symptomatic sciatic nerve compression. To our knowledge, this is the first published case describing this specific postoperative complication and its successful surgical management.

A 66-year-old woman presented with severe, unbearable posterior thigh pain that began immediately after left TKR. The pain was continuous, worse at night, and aggravated by sitting, cycling, or stair climbing. Previous surgeons had attributed the symptoms to complex regional pain syndrome. Clinical examination revealed a Popeye-like deformity of the distal hamstring, a positive Tinel's sign, and localized tenderness over the sciatic nerve. Imaging studies demonstrated a complete rupture of the common hamstring tendon, including the semimembranosus, with an 18.5-cm retraction and entrapment of the semitendinosus tendon against the sciatic nerve. Conservative management with ultrasound-guided perineural infiltrations provided only transient relief. Surgical exploration and neurolysis were therefore performed. Intraoperatively, the sciatic nerve was identified, released from adhesions, and decompressed along its bifurcation. The surrounding musculature appeared atrophic and infiltrated with fatty tissue. Postoperatively, the patient experienced immediate and sustained relief, with the pain score improving from 80/100 to 10/100 and complete functional recovery documented within 2 months. There were no neurological or vascular deficits, and the patient reported maximal satisfaction with the surgical outcome.

This case highlights an exceptionally rare etiology of chronic pain, which started immediately following TKR: a complete proximal hamstring rupture with secondary sciatic nerve compression. Recognition of this condition requires clinical suspicion when patients present with disproportionate posterior thigh pain unresponsive to standard treatment. Early magnetic resonance imaging is essential for accurate diagnosis. Timely surgical neurolysis can achieve excellent functional outcomes. Increased awareness among orthopedic surgeons and rehabilitation specialists may prevent delayed diagnosis and unnecessary patient suffering.