Management Strategies, Complications and Outcomes of Periprosthetic Fractures Around Knee Mega-prosthesis

Abstract Background Mega-prostheses, or endoprosthetic replacements (EPRs), are integral to limb-salvage surgery following tumor resection around the knee. Although implant design has advanced, these reconstructions remain prone to complications and higher failure rates compared with conventional implants. Periprosthetic fractures (PPFs) represent a particularly challenging problem, influenced by mechanical stress, compromised bone stock, and extensive soft-tissue resection. Methods We conducted a retrospective study at a UK tertiary referral center, evaluating the incidence of PPFs between 2010 and 2018, and the management and outcomes of 36 PPFs in 31 patients (median age 34.5 years, range 8–96) treated between 1996 and 2019. Data included demographics, primary diagnosis, fracture classification using the Unified Classification System (UCS), implant stability, treatment modality, and outcomes. Results The incidence of PPFs was 4.9% following proximal tibial resection and 2.8% following distal femoral resection. Of the 36 fractures analyzed, 24 (66.7%) were femoral and 12 (33.3%) tibial; most (83.3%) involved cemented rotating-hinge implants. UCS Type B1 fractures accounted for half of all cases. Non-operative management, employed in nine fractures (25%; six B1 and three C), was uniformly successful with no failures. Operative management (27 fractures, 75%) demonstrated a 44% failure rate, driven primarily by infection. Five patients (16.1%) required amputation, all in association with prosthetic joint infection. Mechanical contributors included cement extravasation (14%) and stem malalignment (8%). Conclusions Non-operative treatment appears effective for select stable and minimally displaced B1 and C fractures, with lower complication rates compared to surgical intervention. Operative strategies carry a high risk of failure, predominantly due to infection, emphasizing the need for stringent infection prevention and individualized treatment planning in this high-risk population.