Implantation of an attachment tube preserves knee extension after nonunion of Felix IV fracture: a case report

BACKGROUND: While commonly utilized to fix tissue and muscles to megaprostheses to restore function and stability after tumor surgery, an attachment tube was used as a synthetic reconstruction of the knee joint’s extension mechanism after nonunion of Felix IV C fracture. Fixation of the tibial fragment, and therefore its osteointegration, is complicated after total knee arthroplasty, causing tibial tubercle dislocation. CASE PRESENTATION: A 61-year-old German patient presented to our clinic with Felix IV C fracture, persistent knee pain, and reduced knee extension strength. In this special case, mobilization and reattachment of the tibial tubercle was not possible because of necrosis and underlying tibial component. Therefore, we covered the defect with cement and used an polyethylene terephthalate tube for knee extension system augmentation. Follow-up after 10 months demonstrated a good clinical result. CONCLUSION: The management of Felix IV C fractures is complicated by the underlying prosthesis resulting in redislocation of the fragment and persistent symptoms of pain and reduced functionality. We here present a new surgical technique to treat periprosthetic fracture complicated by tibial tubercle dislocation. Good clinical and radiologic results on follow-up after 10 months indicate the use of attachment tubes as a suitable surgical technique to restore knee joint extension and to reduce knee pain after dislocated Felix IV C fracture.