(P 97) RISK FACTORS ASSOCIATED WITH AMPUTATION VERSUS CONTINUED LIMB SALVAGE IN LOWER EXTREMITY ENDOPROSTHETIC RECONSTRUCTION

Objective: Endoprosthetic reconstruction has become an increasingly common form of limb salvage in patients with primary or metastatic bone disease. However, up to 10 percent of endoprostheses will eventually fail. The purpose of this study was to identify the factors associated with amputation or continued limb salvage following removal of a lower extremity endoprosthesis.

Methods: A retrospective, single-center study of 78 patients with failure of a primary lower extremity endoprosthesis requiring implant removal between 2000-2022 was performed. Demographic, surgical, and endoprosthesis-related outcomes data were collected and compared between patients who resulted in limb salvage (n= 50) and amputation (n= 28).

Results: Smoking status (OR [95% CI]: 4.074 [1.278, 13.78], p=0.019) and a pre-existing diagnosis of diabetes mellitus (OR [95% CI]: 5.833 [1.539, 18.18], p=0.006) at the time of index endoprosthetic implantation were significantly associated with progression to amputation versus limb salvage. Indication for initial endoprosthetic reconstruction (OR [95% CI]: 1.103 [0.4327, 2.717], p>0.999), was not associated with progression to amputation versus limb salvage. Aseptic loosening as a mode of endoprosthetic failure was associated with limb salvage (10/50 (20.0%) vs. 0/28 (0.0%); p=0.012), while tumor recurrence or progression was associated with progression to amputation (OR [95% CI]: 9.600 [1.940, 46.57], p=0.003). In patients with a deep infection after a primary endoprosthesis, a polymicrobial infection, as compared to monomicrobial or culture negative infection, was not associated with progression to amputation (2/24 (8.3%) vs. 1/19 (5.3%); p=0.864).

Conclusion: Aseptic loosening following endoprosthesis implantation is associated with continued limb salvage. Smoking and diabetes mellitus at the time of endoprosthesis implantation, and tumor recurrence or progression following implantation are associated with progression to amputation. These risk factors may be useful in patient counseling.