Original Article Total Knee Arthroplasty After Lower Extremity Amputation: A Review of 13 Cases Derek F. Amanatullah, MD, PhD, Robert T. Trousdale, MD, Rafael J. Sierra, MD Department of Orthopedic Surgery, Mayo Clinic, Rochester Minnesota abstract article info Article history: Received 26 February 2014 Accepted 31 March 2014 Available online xxxx Keywords: total knee arthroplasty TKA below knee amputation osteoarthritis lower extremity amputation Below knee amputation protects the ipsilateral knee from osteoarthritis and overloads the contralateral knee predisposing it to symptomatic osteoarthritis. We retrospectively reviewed 13 primary total knee arthroplasty (TKAs) in 12 patients with a prior lower extremity amputation. Twelve TKAs were performed on the contralateral side of the amputated limb while only one TKA was performed on the ipsilateral side. The average clinical follow-up was 6.8 ± 4.8 years. Knee Society Scores improved from 30.4 ± 11.8 to 88.5 ± 4.2 after TKA with a prior contralateral amputation. Three (23.1%) patients with TKA after contralateral amputation had aseptic loosening of the tibial component. Patients experience clinically significant improvement with TKA after lower extremity amputation. Augmentation of tibial fixation with a stem may be advisable during TKA after contralateral amputation. © 2014 Elsevier Inc. All rights reserved. In the United States there are about 1.6 million individuals living with a lower extremity amputation and 30,000 to 40,000 lower extremity amputations are performed annually [1]. Most lower extremity amputations are performed for complications of peripheral vascular disease and/or diabetes mellitus. Lower extremity trauma, musculoskeletal tumors, infection or sepsis, and congenital etiologies account for the remainder of lower extremity amputations. Lower extremity amputees are subject to increased physical demands as a result of amputation. The level of lower extremity amputation is directly proportional to the increase in oxygen consumption required for ambulation [2,3]. A retrospective cohort study comparing the prevalence of symptomatic knee osteoarthritis in lower extremity amputees and non-amputees found 10-fold less symptomatic knee osteoarthritis in the amputated limb of the amputee population when compared to the prevalence of symptom- atic knee osteoarthritis of non-amputee population [4]. Several epidemiologic studies also support a 40% to 80% increase in the prevalence of symptomatic knee osteoarthritis in the non-amputated limb of the amputee population when compared to the prevalence of symptomatic knee osteoarthritis of non-amputee population [4–7]. 88% of lower extremity amputees have radiographic evidence of osteoporosis in the amputated limb after below knee amputation [8]. Hence, below knee amputation may unload the ipsilateral knee protecting it from osteoarthritis and overload the contralateral knee predisposing it to symptomatic osteoarthritis. There are only four known cases of total knee arthroplasty (TKA) after ipsilateral lower extremity amputation in the orthopedic literature [9–11]. Additionally, there is no available data regarding the clinical performance of TKA after contralateral lower extremity amputation despite the epidemiologic evidence that contralateral lower extremity amputation may predispose the knee to degenerative joint disease. The clinical and patient reported outcomes of TKA in the amputee population are poorly described in the literature. We present a case of TKA after ipsilateral lower extremity amputation and the first case series of TKA after contralateral lower extremity amputation. Materials and Methods A retrospective review identified a consecutive set of primary TKAs from the authors’ institution over a period between 1988 and 2009. Patients with a minimum of 2 years follow-up after TKA were identified with the use of a total joint registry that has prospectively followed all patients who have undergone a total joint arthroplasty at our institution since 1969. The registry includes patient demographics, date of last evaluation, implant, reoperation, and type of complication. Patients are scheduled for regular clinical evaluations at 1, 2, and 5 years following the arthroplasty and every 5 years thereafter. The institutional review board reviewed and approved this study prior to initiation. Thirteen TKAs performed by 7 surgeons at our institution in 12 patients after lower extremity amputation were identified for inclusion in this study. All TKA implants were cemented and both cruciate-retaining and posterior-stabilized designs were used. The primary endpoint measured was failure defined as revision for any reason. Average age, height, weight, body mass index (BMI) and operative time were recorded (Table 1). The underlying diagnoses for lower extremity amputation were recorded (Table 2). The immediate The Journal of Arthroplasty xxx (2014) xxx–xxx The Conflict of Interest statement associated with this article can be found at http:// dx.doi.org/10.1016/j.arth.2014.03.041. Reprint requests: Rafael J. Sierra, MD, 200 First Street SW, Gonda 14, Rochester, MN 55905. http://dx.doi.org/10.1016/j.arth.2014.03.041 0883-5403/© 2014 Elsevier Inc. All rights reserved. Contents lists available at ScienceDirect The Journal of Arthroplasty journal homepage: www.arthroplastyjournal.org Please cite this article as: Amanatullah DF, et al, Total Knee Arthroplasty After Lower Extremity Amputation: A Review of 13 Cases, J Arthroplasty (2014), http://dx.doi.org/10.1016/j.arth.2014.03.041