Mechanical Failure of SIGMA Total Condylar-III Revision Total Knee System Modular Femoral Component Due to Bolt Screw Breakage - Our Experience in Overcoming Broken Component Incarceration.

Introduction: The rising use of modular implants in revision total knee arthroplasty offers surgeons greater flexibility in addressing bone defects and achieving uniform gaps compared to monoblock counterparts. However, this enhanced functionality brings specific complications such as loosening and breakage at component coupling sites, leading to challenges due to mechanical failures and suboptimal fixation. Extracting broken components during revision surgery poses a significant challenge, prompting innovative techniques to facilitate extraction.

Case Report: We present a rare case of modular femoral component mechanical failure in a 69-year-old male, manifesting as left knee instability and acute pain while walking 4 years following revision of total knee replacement due to infection. Radiographs revealed mechanical failure of the Sigma Total Condylar-III Revision prosthesis bolt, with intra-operative extraction efforts complicated by a lodged broken bolt. Despite initial challenges, successful extraction was achieved using mosquito forceps and a universal nail extractor.

Conclusion: This case highlights the importance of documenting rare instances of mechanical failure in modular implants, emphasizing the need to understand prevalence rates and various surgical techniques for implant extraction. Our experience underscores the utility of the universal nail extractor as a valuable tool in managing difficult implant removal during revision surgery. Surgeons must remain vigilant and innovative in addressing challenges encountered during modular implant revisions.