Complex Two-Stage Revision Total Knee Arthroplasty with Intramedullary Infection Management Using Elastic Titanium Pin Spacer Technique in a Morbidly Obese Patient: A Case Report.

Introduction: Chronic prosthetic joint infection (PJI) with intramedullary extension presents exceptional management challenges in morbidly obese patients. This case demonstrates novel elastic titanium pin spacer fabrication for complex infection control. To the best of our knowledge, this is the first reported case combining intramedullary infection extending to mid-diaphyseal level with innovative spacer design. Case Report: A 60-year-old morbidly obese male 110 kg, body mass index 44 kg/m2 presented with chronic PJI, multiple draining sinuses, and wound dehiscence 14 months post-primary TKA. Multiple previous debridements failed to control infection. Intraoperative findings revealed extensive intramedullary infection extending to mid- diaphyseal level without implant-cement interface involvement. Two-stage revision was performed using an innovative elastic titanium pin Ti-6Al-4V, 2 mm × 200 mm) technique for spacer fabrication and a comprehensive infection management protocol. Results: Despite culture-negative infections, the staged surgical approach achieved complete infection eradication. Patient achieved full weight-bearing at 1 month with 0-110° range of motion. At more than 1 year follow-up, he remains symptom-free with stable prosthetic components and no recurrent infection. Conclusion: This case demonstrates successful management of complex PJI with intramedullary extension using a novel elastic titanium pin spacer technique. The unique presentation provides valuable insights for managing similar complex cases in high-risk populations.